Humanoid robots that mimic human movement have garnered significant attention in recent years. This study focuses on mimicking the efficient pitching motion of humans by incorporating two main approaches into a humanoid robot: (1) the use of elastic elements to assist joint torque, and (2) the optimization of motor torque to minimize energy consumption. This robot is intended to emulate human physical characteristics, such as mass, link length, and center of gravity, with a particular focus on utilizing the elastic energy generated during shoulder internal and external rotation. A leaf spring is attached in parallel with the motor at the shoulder pitch joint to release the elastic energy stored during shoulder external rotation, thereby assisting internal rotation in a manner similar to human biomechanics. Additionally, motor torque optimization is addressed by formulating the torque minimization problem as a combinatorial optimization challenge and solving it using Fujitsu's quantum-inspired Digital Annealer. Experiments conducted through simulations and with an actual pitching robot assessed the effectiveness of these technologies in mimicking human-like pitching motion. The results suggest that combining elastic elements with motion optimization techniques enable robots to achieve more efficient human-like movements.

Teleoperating bipedal humanoid robots presents unique challenges, including decreased stability and reduced operator presence. This paper addresses these challenges by proposing a method that leverages the operator’s inherent sense of stability by feedback from a sole haptics display to operate a bipedal humanoid robot. We developed a bilateral control system that integrates a device replicating sole haptics feedback and provides the operator with feedback on changes in the robot’s center of gravity. We conducted operating experiments in the forward-backward direction to evaluate its effectiveness and investigate the effectiveness of sole haptics on robot operation. The results demonstrate that operating with both vision and sole haptics feedback significantly reduces the robot’s fall rate by over 56% when disturbances are applied, compared to using only vision feedback. Moreover, operators reported a 21% higher sense of presence with both vision and sole haptics feedback compared to using only vision feedback.

Compared to traditional agricultural environments, the high density and diversity of vegetation layouts in Synecoculture farms present significant challenges in locating and harvesting occluded fruits and pedicels (cutting points). To address this challenge, this study proposes a Mask R-CNN-based method for locating fruits (tomatoes, yellow bell peppers, etc.) and estimating the pedicels from RGBD images acquired by a camera moved along fixed paths. After obtaining masks of all fruits and pedicels, this method judges the matching relationship between the located fruit and pedicel according to the 3D distance between the fruit and pedicel. Subsequently, this research determines the least occluded best viewpoint for harvesting based on the visible real areas of located fruits in images acquired under the fixed paths, and harvesting is then completed from this best viewpoint following a straight path. Experimental results show this method effectively identifies occluded targets and their cutting positions in both Gazebo simulation environments and real-world farms. This method can select the least occluded viewpoint for a high harvesting success rate.

In recent years, awareness of improving the quality of medical care has increased. We focused on neonatal resuscitation, which is difficult to train clinically, and our long-term goal is a neonatal resuscitation training system that can simulate cases and can feedback interactively based on quantitative evaluation of the procedures. In this study, we developed the neonatal simulator that has a respiratory movement simulating mechanism and a chest compression measurement mechanism. Through an interview with neonatologists, the fidelity of respiratory movements and the possibility of evaluating chest compression with the developed simulator were assessed.

For a small-sized biomimetic robot, it is challenging to mimic animal-like motion with high speed and high flexibility. To enable high flexibility, high stability, and high biomimicry degree for the robotic rat, we drew inspirations from three agile rat movements, namely, the pitch, yaw, and U-turn movements. First, we proposed key movement joints (KMJs) to capture a decent representation of the rat with a reduced-order model. By extracting the primary KMJs, we determined the number and distribution of robotic joints for the design of a bioinspired spine mechanism. Second, to meet the demand of high biomimicry degree, we generated an optimal compensation term to minimize the trajectory error introduced by simplifying the model. Moreover, we calculated the optimal minimum motion cycle based on the constraints of equilibrium under extreme conditions to ensure high flexibility without compromising the stability. Finally, the proposed method was successfully verified through simulation and experimental tests with a robotic rat endowed with the bioinspired spine mechanism.

Biped robots require massive power on each leg while walking, hopping, and running. We have developed a flow-based control system-called hydraulic direct drive system- that can achieve high output while avoiding spatial limitations. To implement the proposed system with simple equipment configuration, a pump and single-rod cylinder are connected in a closed loop. However, because compensation for flow rate is impossible in a completely closed loop, owing to the difference in the pressure receiving area caused by the rod, a passive flow compensation valve is employed. This valve has a simple structure and is easy to implement. Further, an additional sensor is required to detect the open/close state because the valve state will cause an error in flow control. Therefore, we implemented a model in the controller to predict the state of the flow compensation valve and formulated a method of switching from flow control to pressure control according to the predicted state. Experimental results indicate that the error of the joint angle is reduced to less than 1.6 degrees for walking patterns, and stable walking is realized when the system is installed in biped humanoid robots.

Human jumping involves not only lower limbs but also whole-body coordination. During jumping, the effect of sinking the center of mass for recoil and arm swing are significant, and they can cause changes in the jump height. However, upper body movements during jumping movements of humanoid robots have not been studied adequately. When jumping involves only the lower limbs, the burden on the lower limbs increases and it is difficult to jump as high as humans do. Also, if the sole is in contact with the ground during jumping movements, we cannot make good use of the ankle joint. Humans raise their heels during jumping movements, but there are few cases where humanoid robots achieve these movements. Therefore, we thought that jumping with recoil motion by the sinking, arm swing, and changing in foot contact status could result in a higher jump height higher than that possible with only lower limb movements. Hence, in this study, we generated jumping motion using sinking, arm swing and changing foot posture. First, a center of mass trajectory was generated by planning the entire jumping motion, and at the same time, the angular momentum was determined for stability. Next, the joint trajectory was calculated using these two parameters. At that time, arm trajectory and foot posture were specified in the null space. This generated a jumping motion considering arm swing. During simulations, this method provided a jump height almost four times the jump height that obtained without arm swing.

Biped robots require substantial amounts of power alternately on each leg while walking, hopping, and running. However, it is difficult to mount high-power large electrical motors in conventional mechanical transmission systems owing to spatial limitations. A hydraulic direct-drive system is proposed in which the size of the motor in each leg can be reduced by sharing the motor outputs between the legs. In this paper, the hydraulic direct-drive system is evaluated in an actual hydraulic system. Velocity followability, excellent energy saving, and virtually perfect position tracking are achieved with the proposed system. The results of performance comparison with a valve-based control system show that energy consumption is controlled and good position-following capability is achieved using the proposed system.

Social interaction between a robot and rats is important since the robot can generate reproducible social behaviors across trials. However, lacking internal state feedback from the rat makes current robot-rat interaction a very preliminary level comparing with rat-rat interaction. Previous biological studies showed that ultrasonic vocalizations (USVs) emitted by a rat are expressions of its internal emotional states, which therefore can be used as part of feedback for a robot-rat interaction. The challenge is to accurately identify rat USVs in real-time from mix sounds generated by the robot in a noisy environment. To address these problems, we propose an SVM-based rat USVs identification method. This SVM method uses three types of features to represents the characteristics of mix sound and use these multidimensional features to identify rat USVs. Results show that our identification method has an accuracy of 84.29% with only 4.84% false-positive rate. Furthermore, we carefully design the filter window length with respect to sound chunk length and use only one microphone to record the mix sound. All of these efforts are to reduce the calculation time to realize real-time identification. Eventually, the identification process can be executed within 3. 5ms, which definitely meet the real-time demand. This research lays the foundation of the feedback based interaction between rat and robot, and also shows promise in the study of ethology and the interaction between robot and animals.

In this paper, we describe approaches to enable a four-limbed robot to get over a step higher than its leg with torso contact. The higher the step becomes, the more difficult it is for legged robots to get over from the viewpoint of stability and kinematic reachability. Torso landing contributes to improving stability and robustness of motion for moving onto high step because of lower center of mass (CoM) and larger support polygon, which is seldomly utilized by previous human-sized legged robots. The approaches in this paper consist of the following two components. As for hardware, spikes are arranged on the bottom of robot’ s body for stable torso landing on a high step. As for motion generation, Sequential Quadratic Programming (SQP) is utilized to generate motion with torso landing to guarantee stability of robots during getting over the high step. From experiments, it is confirmed that the fourlimbed robot WAREC-I succeeded in moving onto a step with the height of 865mm.

For building a disaster response robot, WAREC-l's fully-automated system for manipulating a valve, this paper proposes a method for (1) detecting a valve which is far away from the robot, (2) estimating the position and orientation for grasping the valve by the robot at a closer position. Our methods do not need any prior information about a valve for the above-mentioned detection and estimation for grasping. In addition, our estimation for grasping provides useful information, by which WAREC-I can rotate a valve autonomously. The method (1) uses the RGB image and the point cloud data captured by Multisense SL as the input, and estimate the position and orientation of a valve far away from the robot. The method (2) uses both the RGB and depth images captured by KinectV2 as input and estimate information for grasping the valve. Our experiments are conducted using a real disaster response robot. Our experimental results show the error of the estimation by the (a) two methods are small enough to achieve a fully-automated system for detecting and rotating the valve by WAREC-I.

Biped robots require substantial amounts of power on each leg alternately while walking, hopping, and running. However, it is difficult to adopt large high-power electrical motors in conventional mechanical transmission systems owing to spatial limitations. To address this problem, a hydraulic interlocking drive system that incorporates two hydraulic direct-drive systems is proposed for biped humanoid robots. The hydraulic interlocking drive system connects the two hydraulic direct-drive systems and concentrates the pump output on one side cylinder. The other side cylinder meter-in flow rate is controlled by the meter-out flow rate from the cylinder on which the pump is concentrated. Good position tracking and excellent energy saving are achieved with the proposed system. A performance comparison with a single hydraulic direct-drive system shows that the motor power of the hip pitch joint is reduced by 27.3% for walking patterns. This result shows that the rated output of the motor can be reduced, and smaller and lighter motors can be installed in biped robots.

In this paper, a system to determine the emotion of a group of people via facial expression analysis is proposed for the Waseda Entertainment Robots. General models and standard methods for emotion definition and recognition are briefly described, as well as strategies for computing the group global emotion, knowing the individual emotions of group members. This work is based on Ekman's extended “Big Six” emotional model, popular in Computer Science and Affective Computing. Emotion recognition via facial expression analysis is performed with a cloud-computing based solution, using Microsoft Azure Cognitive services. First, the performances of both the Face API to detect faces, and Emotion API, to compute emotion via face expression analysis, are tested. After that, a solution to compute the emotion of a group of people has been implemented and its performances compared to human perceptions. This work presents concepts and strategies which can be generalized for applications within the scope of assistive robotics and, more broadly, affective computing, wherever it will be necessary to determine the emotion of a group of people.

In this paper, we propose an end-effector for realizing various locomotion modes and simple work of a legged robot. The locomotion modes include climbing a vertical ladder, crawling, and walking. The simple work includes grasping and switching motions required at a disaster site. The developed end-effector has a two-pronged hook shape and two fingers for grasping and working and can be used to perform the locomotion and manipulation tasks described above. The experimental results confirmed that the four-limb robot WAREC-1 (WAseda REsCuer-No. 1) equipped with our proposed end-effector was able to climb a vertical ladder and perform the crawling motion. We also confirmed that the end-effector could grasp and switch five types of objects: a cylinder, cylinder with trigger, T-shaped, disk, and thin plate.

To improve the movement ability of humanoid robots, instead of traditional methods dependent on only power of actuators, there is possibility that utilizing elasticity inspired from collaboration of muscle and tendon of human is effective to achieve high-power movement. In this study, we aimed to realize a jumping motion that accumulates energy more appropriately in spring by combining active joint driving with spring behavior like human tendons and muscles. We proposed a countermovement jump method using the resonance with the leg's active pushing-off movement and leg stiffness. To achieve active pushing-off and joint stiffness, we developed a new joint mechanism using leaf springs and an actuator unit with a worm gear. We then performed experiments to evaluate the effectiveness of the proposed mechanism and methods. Finally, the robot achieved a countermovement jump using active kicking and leg's elasticity.

Humans utilize their torsos and arms while running to compensate for the angular momentum generated by the lower-body movement during the flight phase. To enable this capability in a humanoid robot, the robot should have human-like mass, a center of mass position, and inertial moment of each link. To mimic this characteristic, we developed an angular momentum control method using a humanoid upper body based on human motion. In this method, the angular momentum generated by the movement of the humanoid lower body is calculated, and the torso and arm motions are calculated to compensate for the angular momentum of the lower body. We additionally developed the humanoid upper-body mechanism that mimics the human link length and mass property by using carbon fiber reinforced plastic and a symmetric structure. As a result, the developed humanoid robot could generate almost the same angular momentum as that of human through human-like running motion. Furthermore, when suspended in midair, the humanoid robot produced the angular momentum compensation in the yaw direction.

This paper describes a novel four-limbed robot having high mobility capability in extreme environments. At disaster sites, there are various types of environments where a robot must move such as rough terrain with possibility of collapse, narrow places, stairs, vertical ladders and so forth. In this paper, first we categorized extreme environments based on three indexes: unevenness, narrowness, and inclination. To move in such extreme environments, we proposed a four-limbed robot having various locomotion styles such as bipedal/quadrupedal walking, crawling and ladder climbing. The main contribution of this paper is the concept and hardware design of the four-limbed robot. We developed a prototype of the four-limbed robot having commonly structured limbs. The number of DoF for the whole body is 29, with 7-DoFs in each limb and 1-DoF in the trunk. The robot weight is 110 kg, and the height is 1,290 mm when standing on two legs. The end-effector has hook-like shape. Verification of the prototype robot is conducted through simulations and experiments.

The interaction test between a robotic rat and living rat is considered as a possible way to quantitatively characterize the rat sociality. In such robot-rat interactions, the robot should be designed to fully replicate a real rat in terms of morphological and behavioral characteristics. To address this problem, a multi-jointed robot prototype has been modified based on our previous work. We optimally update the forelimb of the robot and redesign the control board to make it more dexterous and increase its behavioral capability. Then, we systematically and kinematically analyze the rotational range of joint variables and the workspace of the robot by using traversal method. To evaluate the motion capability of the modified robot, we propose two quantitative parameters: maximum reachable height (MRH) and minimum bendable distance (MBD). Additionally, we achieve to quantitatively evaluate the behavioral similarity between the robot and rat with the calculated accumulative distance (AD) by using dynamic time warping (DTW). These evaluated methods show high promise to improve the robot-rat interaction to be more similar to rat-rat interaction.

This paper describes an approach that enables the four-limbed robot “WAREC-1” to climb up and down vertical ladders stably. First, the four-limbed robot “WAREC-1” is introduced and dynamic stability conditions in multi-mass model for ladder climbing are proposed as the basis of judging whether a four-limbed robot is stable or not while climbing a vertical ladder. According to the proposed stability conditions, 3 different types of moment will directly affect the stability of the robot on a ladder: gravitational moment, inertial moment and reaction force moment. With the analysis of these 3 kinds of moments and the relationship among them, stability control methods are proposed to maintain stability of the robot on a ladder to the greatest degree and avoid their mutual interference. Combining with the stability conditions and stability control proposed, stable motion planning of climbing up and down a vertical ladder, a motion planning method proposed by the authors that allows independent path and time planning in trajectory planning is also applied to reinforce the efficiency of the stability control. Eventually, results from the simulation and physical robot verify the validity of the proposed control methods.

We developed a four-arm four-crawler advanced disaster response robot called OCTOPUS. Disaster response robots are expected to be capable of both mobility, e.g., entering narrow spaces over very rough unstable ground, and workability, e.g., conducting complex debris-demolition work. However, conventional disaster response robots are specialized in either mobility or workability. Moreover, strategies to independently enhance the capability of crawlers for mobility and arms for workability will increase the robot size and weight. To balance environmental applicability with the mobility and workability, OCTOPUS is equipped with a mutual complementary strategy between its arms and crawlers. The four arms conduct complex tasks while ensuring stabilization when climbing steps. The four crawlers translate rough terrain while avoiding toppling over when conducting demolition work. OCTOPUS is hydraulic driven and teleoperated by two operators. To evaluate the performance of OCTOPUS, we conducted preliminary experiments involving climbing high steps and removing attached objects by using the four arms. The results showed that OCTOPUS completed the two tasks by adequately coordinating its four arms and four crawlers and improvement in operability needs.

This paper describes the development of one DoF robotic hand that makes human laugh by tickling through rubbing underarm. Laughter is attracting research attention because it enhances health by treating or preventing mental diseases. However, laughter has not been used effectively in healthcare because the mechanism of laughter is complicated and is yet to be fully understood. The development of a robot capable of making humans laugh is useful for clarifying the mechanism of laughter because the stimuli by the robot is quantitative and reproductive. Especially, tickling matches to this purpose because the relationship between stimuli and reaction is simpler compared to other techniques. Therefore, this research aimed to develop a robotic hand that can output quantitative and reproductive tickling stimuli for clarifying the mechanism of laughter. Rubbing underarm is selected as a target motion of robot because previous research suggested that this is the best way for making humans feel ticklish. In order to achieve the tickling motion by robots as humans, the required specifications were determined through experimental method. In order to develop a robot that achieves the required fingertip trajectory by simple mechanisms as much as possible, mechanism with crank and link driven by single motor was developed. The result of experimental evaluation shows that the developed robot could make humans laugh by its rubbing motion. In addition, the quantitative tickling motion by developed robotic hand was suggested to be effective for clarifying the mechanism of laughter.

Cats have protractible claws to fold their tips to keep them sharp. They protract claws while hunting and pawing on slippery surfaces. Protracted claws by tendons and muscles of toes can help cats anchoring themselves steady while their locomotion trends to slip and releasing the hold while they retract claws intentionally. This research proposes a kind of modularized self-adaptive toe mechanism inspired by cat claws to improve the extremities' contact performance for legged robot. The mechanism is constructed with four-bar linkage actuated by contact reaction force and retracted by applied spring tension. A feasible mechanical design based on several essential parameters is introduced and an integrated Sole-Toe prototype is built for experimental evaluation. Mechanical self-adaption and actual contact performance on specific surface have been evaluated respectively on a biped walking platform and a bench-top mechanical testing.

This paper introduces a motion planning method to generate ladder climbing motion for a four-limbed robot. This method contains the following points: (1) independent planning of path and time in 3 dimensional space for trajectory planning; (2) path length minimization according to given midpoints. In trajectory planning, arc-length parameterization is used to separate path planning and time planning so that they can be done independently. After path is planned, time planning along the planned path can be given freely to meet our requirement, such as speed and acceleration adjustment for the protection of motors, optimization for dynamics analysis, dynamic obstacle avoidance and so on. Results from simulations and experiments authenticate the validity of our motion generation method.

Stereo confidence measures are important functions for global reconstruction methods and some applications of stereo. In this article we evaluate and compare several models of confidence which are defined at the whole disparity range. We propose a new stereo confidence measure to which we call the Histogram Sensor Model (HSM), and show how it is one of the best performing functions overall. We also introduce, for parametric models, a systematic method for estimating their parameters which is shown to lead to better performance when compared to parameters as computed in previous literature. All models were evaluated when applied to two different cost functions at different window sizes and model parameters. Contrary to previous stereo confidence measure benchmark literature, we evaluate the models with criteria important not only to winner-take-all stereo, but also to global applications. To this end, we evaluate the models on a real-world application using a recent formulation of 3D reconstruction through occupancy grids which integrates stereo confidence at all disparities. We obtain and discuss our results on both indoors' and outdoors' publicly available datasets.

Energy efficiency and robustness of locomotion to different terrain conditions are important problems for humanoid robots deployed in the real world. In this paper, we propose a footstep-planning algorithm for humanoids that is applicable to flat, slanted, and slippery terrain, which uses simple principles and representations gathered from human gait literature. The planner optimizes a center-of-mass (COM) mechanical work model subject to motion feasibility and ground friction constraints using a hybrid A* search and optimization approach. Footstep placements and orientations are discrete states searched with an A* algorithm, while other relevant parameters are computed through continuous optimization on state transitions. These parameters are also inspired by human gait literature and include footstep timing (double-support and swing time) and parameterized COM motion using knee flexion angle keypoints. The planner relies on work, the required coefficient of friction (RCOF), and feasibility models that we estimate in a physics simulation. We show through simulation experiments that the proposed planner leads to both low electrical energy consumption and human-like motion on a variety of scenarios. Using the planner, the robot automatically opts between avoiding or (slowly) traversing slippery patches depending on their size and friction, and it chooses energy-optimal stairs and climbing angles in slopes. The obtained motion is also consistent with observations found in human gait literature, such as human-like changes in RCOF, step length and double-support time on slippery terrain, and human-like curved walking on steep slopes. Finally, we compare COM work minimization with other choices of the objective function.

Laughter is a very interesting non-verbal human vocalization. It is classified as a semi voluntary behavior despite being a direct form of social interaction, and can be elicited by a variety of very different stimuli, both cognitive and physical. Automatic laughter detection, analysis and classification will boost progress in affective computing, leading to the development of more natural human-machine communication interfaces. Surface Electromyography (sEMG) on abdominal muscles or invasive EMG on the larynx show potential in this direction, but these kinds of EMG-based sensing systems cannot be used in ecological settings due to their size, lack of reusability and uncomfortable setup. For this reason, they cannot be easily used for natural detection and measurement of a volatile social behavior like laughter in a variety of different situations. We propose the use of miniaturized, wireless, dry-electrode sEMG sensors on the neck for the detection and analysis of laughter. Even if with this solution the activation of specific larynx muscles cannot be precisely measured, it is possible to detect different EMG patterns related to larynx function. In addition, integrating sEMG analysis on a multisensory compact system positioned on the neck would improve the overall robustness of the whole sensing system, enabling the synchronized measure of different characteristics of laughter, like vocal production, head movement or facial expression; being at the same time less intrusive, as the neck is normally more accessible than abdominal muscles. In this paper, we report laughter discrimination rate obtained with our system depending on different conditions.

Analysis of human running has revealed that the motion of the human leg can be modeled by a compression spring because the leg's joints behave like a torsion spring in the stance phase. Moreover, the knee bends rapidly to avoid contact of the foot with the ground in the swing phase. In this paper, we describe the development of a knee joint mechanism that mimics the elastic characteristics of the stance leg and rapid bending knee of the idling leg of a running human. The knee was equipped with a mechanism comprising two leaf springs and a worm gear for adjusting the joint stiffness and high-speed bending knee. Using this mechanism, we were able to achieve joint stiffness within the range of human knee joints that could be adjusted by varying the effective length of one of the leaf springs. In addition, the mechanism was able to bend rapidly by changing the angle between the two leaf springs. The equation proposed for calculating the joint stiffness considers the difference between the position of the fixed point of the leaf spring and the position of the rotational center of the joint. We evaluated the performance of the adjustable joint stiffness and the effectiveness of the proposed equation for joint stiffness and high-speed knee bending. We were able to make a bipedal robot hop using pelvic oscillation for storing energy produced by the resonance to leg elasticity and confirmed the mechanism could produce large torque 210 Nm.

Human running motion can be modeled using a spring-loaded inverted pendulum (SLIP), where the linear-spring-like motion of the standing leg is produced by the joint stiffness of the knee and ankle. To use running speed control in the SLIP model, we should only decide the landing placement of the leg. However, for using running speed control with a multi-joint leg, we should also decide the joint angle and joint stiffness of the standing leg because these affect the direction of the ground reaction force. In this study, we develop a running control method for a human-like multi-joint leg. To achieve a running motion, we developed a running control method including pelvis oscillation control for attaining jumping power with the joint stiffness of the leg and running speed control by changing the landing placement of the leg. For using running speed control, we estimated the ground reaction force using the equation of motion and detected the joint angles of the leg for directing the ground reaction force toward the center of mass. To evaluate the proposed control methods, we compared the estimated ground reaction force with the force measured by the real robot. Moreover, we performed a running experiment with the developed running robot. By using ground reaction force estimation, this robot could accomplish the running motion with pelvic oscillation for attaining jumping power and running speed control.

Environment recognition is an effective way for a mobile robot to move across rough terrain. In particular, this makes it possible to prevent a tiny mobile robot from getting stuck or turning over. Several studies have been conducted on environment recognition using a laser range finder or camera. However, almost all of these studies focused on obstacle detection or shape recognition, which cannot be used to recognize the surface condition such as slipperiness. The purpose of this work is to design a model for estimating the surface condition using a tiny mobile robot. We set slipperiness as one of the parameters for recognizing the surface condition, which is already used by terramechanics, along with two additional parameters, the hardness and unevenness. We find that a robot can roughly estimate the ground hardness by measuring the current peak of a motor and the unevenness from measuring the robot posture. By recognizing the surface condition, the robot can change the parameters of the controlling motor based on the ground characteristics. This new method for recognizing the surface condition is significant, not only because it fills gaps in the previous research, but also because it does not require any special sensors such as a laser range finder and does not consume a large quantity of energy. Therefore, it achieves a core objective of our environmental monitoring system using multiple mobile robot.

Robots are possible candidates for performing tasks as helpers in activities of daily living in the future: working as a receptionist is one possible employment. However, the way the receptionist robot should appear, sound and behave needs to be investigated carefully, in order to design a robot which is accepted and perceived in a positive way by common users. This paper describes a study on anthropomorphism of a receptionist robot made for Brazilian people depending on the appearance and on the voice of the receptionist. This experiment was preceded by a preliminary survey about expectation of people regarding receptionists. The main experiment consisted in having Brazilian people interacting with a conversational agent and with a humanoid robot through a video conference. The two receptionists are not only different in physical appearance, but in the sound of the voice, too, which can be either human-like or robotic sound. The two receptionists gave indications to the participants to reach rooms where they could evaluate the receptionists through questionnaires concerning anthropomorphism and uncanniness among other concepts. The results gathered from both experiments provide useful hints to design a receptionist robot.

This paper describes the bipedal humanoid robot that makes human laugh with its whole body expression and affect human's psychological state. In order to realize "Social interaction" between human and robot, the robot has to affect human's psychological state actively. We focused on "laugh" because it can be thought as a typical example for researching "Social interaction". Looking through a Japanese comedy style called "manzai" or the art of conversation, we picked out several methods for making human laugh. Then we made several skits with the advice of comedians, and made the whole body humanoid robot perform them. Results of experimental evaluation with these skits shows that the robot's behavior made subjects laugh and change their psychological state seen as a decrease of "Depression" and "Anger".

Human running motion can be modeled by a spring loaded inverted pendulum (SLIP). However, this model, despite being widely used in robotics, does not include human-like pelvic motion. In this study, we show that the pelvis actually contributes to the increase in jumping force and absorption of landing impact, both of which findings can be used to improve running robots. On the basis of the analysis of human running motion, we propose a new model named SLIP2(spring loaded inverted pendulum using pelvis). This model is composed of a body mass, a pelvis, and leg springs; the model can control its springs during running by use of pelvic movement in the frontal plane. To achieve hopping and running motions, we developed pelvis oscillation control, running velocity control, and stabilization control using an upper body, as control methods. We also developed a new hopping robot using the SLIP2model. To evaluate the proposed model and control methods, we performed hopping and running simulations. The simulation results showed that the SLIP2model successfully achieves hopping and running motions. The hopping robot was also able to accomplish hopping motion. The simulation results also showed that the difference between the pelvic rotational phase and the phase of oscillation of the mass vertical displacement affects the jumping force. In particular, the results revealed that the human-like pelvic rotation contributes to the absorption of landing impact and to the increase in takeoff forces, which validates our observations in human motion analysis.

In the past we achieved to use a rat-like robot and a single rat to develop Animal Models of Mental Disorder (AMMDs) through stress exposure. However, to simulate the real social environment, we use a rat-like robot composed of multiple links to chase a specific rat (target) in a group of rats (outside observers). In this paper, we aim to develop a real-time control system for a multi-link robot surrounded by multiple rats. A virtual impedance model was adopted to generate posture and trajectory for a multi-link robot named WR-5. With the analysis of virtual forces/moments acting on WR-5 based on the model, corresponding dynamic equations can be obtained to control the motion of WR-5. Simulation results show that the head of WR-5 can accurately direct a target object in the following test. After conducting experiments with three rat subjects (a target rat, two outside observers), the output results suggest that the head and body gesture of WR-5 achieves to follow the target in real-time. Meanwhile, the control system allows real-time avoidance of the moving outside observers during interaction.

We present a grid-based 3D reconstruction method which integrates all costs given by stereo vision into what we call a Cost-Curve Occupancy Grid (CCOG). Occupancy probabilities of grid cells are estimated in a Bayesian formulation, from the likelihood of stereo cost measurements taken at all distance hypotheses. This is accomplished with only a small set of probabilistic assumptions which we discuss in the paper. We quantitatively characterize the method's performance under different conditions of both image noise and number of used stereo pairs, compared also to traditional algorithms. We complement the study by giving insights on design choices of CCOGs such as likelihood model, window size of the cost function and use of a hole filling method. Experiments were made on a real-world outdoors dataset with ground-truth data.

This paper describes the development of a robotic head that has cartoon facial expression ability with comic marks. For communicating with humans, robots should have expressive facial expression ability for indicating their inner state. Our previous research suggests that robots can express its emotion clearly if it performs facial expressions that are adapted to the cultural background of the communication partner. As a first step, we focus on making expressions for Japanese people. Comic mark is a unique and famous way of emotion expression in Japanese culture. First, we defined facial expressions by combining cartoon-like shape of the facial parts with high emotion recognition rates. Then we asked cartoonists to draw comic marks which they think are effective for emotion expression and find the effective comic marks as “Cross popping veins” for “Anger”, “Tear mark” for “Sadness” and “Vertical lines” for “Fear”. Finally we obtained a model expression which has sufficiently high emotion recognition rate from the combination of the facial expression and the comic marks. In order to achieve these expressions, we developed flexible full color LED display matrix module and mechanism that push and pull the sheet for expressing black lines. Results of experimental evaluation shows that the new robotic head has over 90% average emotion recognition rates for each of the six basic emotions. The results with non-Japanese subjects suggests that impression of emotion expression on robotic head changes depending on the cultural background. These findings encourage us in pursuing this concept of designing robots that display emotions that are adapted to cultural background of communication partner.

Humanoid robots have this formidable advantage to possess a body quite similar in shape to humans. This body grants them, obviously, locomotion but also a medium to express emotions without even needing a face. In this paper we propose to study the effects of emotional gaits from our biped humanoid robot on the subjects' perception of the robot (recognition rate of the emotions, reaction time, anthropomorphism, safety, likeness, etc.). We made the robot walk towards the subjects with different emotional gait patterns. We assessed positive (Happy) and negative (Sad) emotional gait patterns on 26 subjects divided in two groups (whether they were familiar with robots or not). We found that even though the recognition of the different types of patterns does not differ between groups, the reaction time does. We found that emotional gait patterns affect the perception of the robot. The implications of the current results for Human Robot Interaction (HRI) are discussed.

In this study we describe a shoes-wearable foot mechanism which mimics human's foot arch structure and the characteristics of the foot skin to examine the effect of the human foot on biped walking. We approximate the arch structure by a rotational spring and model the human's foot skin with compression springs. The mimesis of the foot arch elasticity is realized by using compression springs. Regarding the characteristics of human's foot skin, first we develop a measuring equipment to measure the human's plantar transverse elasticity. We set the target value of the modulus of transverse elasticity of the foot skin to 11.2 N/mm, and we set the modulus of compression elasticity to 0.136 MPa, referring to a relevant study. The characteristics of human's foot skin are mimicked by using a super-soft urethane resin called Hitohada-gel with 8 mm thick. Through evaluation tests we confirmed that the shoes-wearable foot mechanism could mimic well the characteristics of human's foot arch and skin.

In this paper a novel approach to kinematics learning and task space control, under switching contexts, is presented. Such non-stationary contexts may appear in many robotic tasks: in particular, the changing of the context due to the use of tools with different lengths and shapes is herein studied. We model the robot forward kinematics as a multi-valued function, in which different outputs for the same input query are related to actual different hidden contexts. To do that, we employ IMLE, a recent online learning algorithm that fits an infinite mixture of linear experts to the online stream of training data. This algorithm can directly provide multi-valued regression in a online fashion, while having, for classic single-valued regression, a performance comparable to state-of-the-art online learning algorithms. The context varying forward kinematics is learned online through exploration, not relying on any kind of prior knowledge. Using the proposed approach, the robot can dynamically learn how to use different tools, without forgetting the kinematic mappings concerning previously manipulated tools. No information is given about such tool changes to the learning algorithm, nor any assumption is made about the tool kinematics. To our knowledge this is the most general and efficient approach to learning and control under discrete varying contexts. Some experimental results obtained on a high-dimensional simulated humanoid robot provide a strong support to our approach.

This paper describes the implementation in a walking humanoid robot of a mental model, allowing the dynamical change of the emotional state of the robot based on external stimuli; the emotional state affects the robot decisions and behavior, and it is expressed with both facial and whole-body patterns. The mental model is applied to KOBIAN-R, a 65-DoFs whole body humanoid robot designed for human-robot interaction and emotion expression. To evaluate the importance of the proposed system in the framework of human-robot interaction and communication, we conducted a survey by showing videos of the robot behaviors to a group of 30 subjects. The results show that the integration of dynamical emotion expression and locomotion makes the humanoid robot more appealing to humans, as it is perceived as more “favorable” and “useful”, and less “robot-like".

This paper describes the development of a new shank mechanism and mimicking the human-like walking in the horizontal and frontal plane. One of human walking characteristics is that the COM (Center Of Mass) motion in the lateral direction is as small as 30 mm. We assume that it is thanks to the human walking characteristics in the horizontal plane that the step width is as narrow as 90 mm and the foot rotation angle is 12 deg. To mimic these characteristics, we developed a new shank and implemented it in a humanoid robot WABIAN-2RIII. It has a parallel mechanism which mimics the shank's size of human. Thanks to its size almost the same as human's the robot is capable of realizing gait with the narrow step width of 90 mm and the foot rotation angle of 12 deg. We evaluated the performance of the shank using WABIAN-2RIII. The robot could realize stepping in place with lateral displacement of CoM within 34 mm, which is almost as small as that of human.

Neurologic examination procedures require not only abundant knowledge but also prominent skills. During medical education and training, several methods will be put to use such as watching video, reading books, making use of the simulated patient (SP), and so on. These can help medical staffs, especially novices, to master the skills and accumulate experiences. To make up for the drawbacks of the above methods, such as lack of active interactions, limitation of multi-symptom reproductions, etc, the medical training simulators have been developed to improve training effectiveness. However, most of these simulators only mimic the symptoms. They have no the abilities to show the pathology of diseases. This limits the training effectiveness. In this paper, we propose an elbow robot named WKE-1(Waseda Kyotokagaku Elbow Robot No.1) for neurologic examination training as one part of the whole body patient robot named WKP (Waseda Kyotokagaku Patient). In this robot, we simulate various symptoms occurring during the examination of elbow force, biceps tendon reflex, involuntary action, and also make a physiological neurological model to simulate the pathology of the nervous system. Taking advantage of this robot, the trainee can get a systematic training on both the skills and knowledge. Finally, we take a set of experiments to verify our proposed mechanism and system. The experimental results lead to the consideration that the approach is worth following in further research.

Extensive literature has been written on occupancy grid mapping for different sensors. When stereo vision is applied to the occupancy grid framework it is common, however, to use sensor models that were originally conceived for other sensors such as sonar. Although sonar provides a distance to the nearest obstacle for several directions, stereo has confidence measures available for each distance along each direction. The common approach is to take the highest-confidence distance as the correct one, but such an approach disregards mismatch errors inherent to stereo. In this work, stereo confidence measures of the whole sensed space are explicitly integrated into 3D grids using a new occupancy grid formulation. Confidence measures themselves are used to model uncertainty and their parameters are computed automatically in a maximum likelihood approach. The proposed methodology was evaluated in both simulation and a real-world outdoor dataset which is publicly available. Mapping performance of our approach was compared with a traditional approach and shown to achieve less errors in the reconstruction.

The understanding of emotions in humans is really important in the Human-Robot Interaction field. The affective state of a person can be expressed in several ways, one of them being through the way we walk and our gait can convey emotional clues in social context. Those clues can be used to improve the personal interactions with our peers or add meaning to any message we want to express. However, only a few studies in humanoid robotics were done on the effects of the emotions on the walking. In this paper, we propose to assess the emotional walking patterns created from motion capture data with a survey. Those patterns represent different emotions (sadness, happiness) with different intensities (middle, high and exaggerated). Those emotional walking patterns achieved a high recognition rate of the emotions and the subjects (N=13) could recognize whole body emotions without facial expression on our humanoid robot. Additionally, we found out that at first people might perform poorly at recognizing emotions and their intensities but can get better, even without correction or feedback on their performances.

A complex relationship exists between national cultural background and interaction with robots, and many earlier studies have investigated how people from different cultures perceive the inclusion of robots into society. Conversely, very few studies have investigated how robots, speaking and using gestures that belong to a certain national culture, are perceived by humans of different cultural background. The purpose of this work is to prove that humans may better accept a robot that can adapt to their specific national culture. This experiment of Human-Robot Interaction was performed in Egypt. Participants (native Egyptians versus Japanese living in Egypt) were shown two robots greeting them and speaking respectively in Arabic and Japanese, through a simulated video conference. Spontaneous reactions of the human subjects were measured in different ways, and participants completed a questionnaire assessing their preferences and their emotional state. Results suggested that Egyptians prefer the Arabic version of the robot, while they report discomfort when interacting with the Japanese version. These findings confirm the importance of a culture-specific customisation of robots in the context of Human-Robot Interaction.

This paper describes a walking stabilization control based on gait analysis for a biped humanoid robot. We have developed a human-like foot mechanism mimicking the medial longitudinal arch to clarify the function of the foot arch structure. To evaluate the arch function through walking experiments using a robot, a walking stabilization control should also be designed based on gait analysis. Physiologists suggest the ankle, hip and stepping strategies, but these strategies are proposed by measuring human beings who are not “walking” but “standing” against force disturbances. Therefore, first we conducted gait analysis in this study, and we modeled human walking strategy enough to be implemented on humanoid robots. We obtained following two findings from gait analysis: i) a foot-landing point exists on the line joining the stance leg and the projected point of CoM on the ground, and ii) the distance between steps is modified to keep mechanical energy at the landing within a certain value. A walking stabilization control is designed based on the gait analysis. Verification of the proposed control is conducted through experiments with a human-sized humanoid robot WABIAN-2R. The experimental videos are supplemented.

This paper describes a walking stabilization control on a soft ground based on gait analysis for a humanoid robot. There are many researches on gait analysis on a hard ground, but few scientists analyze the walking ability of human beings on a soft ground. Therefore, we conducted anthropometric measurement using a motion capture system on a soft ground. By analyzing experimental data, we obtained two findings. The first finding is that although there are no significant differences in step width and step length, step height tends to increase to avoid the collision between the feet and a soft ground. The second finding is that there are no significant differences in the lateral CoM trajectories but the vertical CoM amplitude increases when walking on a soft ground. Based on these findings, we developed a walking stabilization control to stabilize the CoM motion in the lateral direction on a soft ground. Verification of the proposed control is conducted through experiments with a human-sized humanoid robot WABIAN-2R. The experimental videos are supplemented.

We describe an interactive learning strategy that enables a humanoid robot to build a representation of its workspace: we call it a Reachable Space Map. The robot learns this map autonomously and online during the execution of goal-directed reaching movements; reaching control is based on kinematic models that are learned online as well. The map can be used to estimate the reachability of a fixated object and to plan preparatory movements (e.g. bending or rotating the waist) that improve the effectiveness of the subsequent reaching action. Three main concepts make our solution innovative with respect to previous works: the use of a gaze-centered motor representation to describe the robot workspace, the primary role of action in building and representing knowledge (i.e. interactive learning), the realization of autonomous online learning. We evaluate our strategy by learning the workspace of a simulated humanoid robot and we show how this knowledge can be exploited to plan and execute complex actions, like whole-body bimanual reaching.

This paper describes the development of a new expressive robotic head for the bipedal humanoid robot. Facial expressions of our old robotic head have low facial expression recognition rate and in order to improve it we asked amateur cartoonists to create computer graphics (CG) images. To realize such expressions found in the CGs, the new head was provided with 24-DoFs and facial color. We designed compact mechanisms that fit into the head, which dimensions are based on average adult Japanese female size. We conducted a survey with pictures and videos to evaluate the expression ability. Results showed that facial expression recognition rates for the 6 basic emotions are increased compared to the old KOBIAN's head.

The results of the neuroscientific research show that humans tend to stabilize the head orientation during locomotion. In this paper we describe the implementation of inverse kinematics based head stabilization controller on the humanoid platform. The controller uses the IMU feedback and controls neck joints in order to align the head orientation with the global orientation reference. Thanks to the method, we can decouple the orientational motion of the head from the rest of the body. This way stabilized head becomes better platform for proprioceptive sensory apparatus, such as cameras or IMU. In the paper we present three experiments which prove that the method has good performance in damping both, high and low frequency motion of the head. We also prove that the proposed controller improves the stability of the tracked goal point on the image of in-built camera.

Humanoid robots are complex sensorimotor systems where the existence of internal models are of utmost importance both for control purposes and for predicting the changes in the world arising from the system's own actions. This so-called expected perception relies on the existence of accurate internal models of the robot's sensorimotor chains.

This paper proposes the use of a specific mathematical model to represent the relationship between rat behavior and sociality (degree of friendliness with the robot) in the robot-rat interaction system. To validate the model, we conducted social interaction test between a rat-like robot and real, live rats. A rat-like robot called WR-4 capable of generating friendly or neutral behaviors among rats serves as partner to the rats in the interaction. Meanwhile, we performed Principal Component Analysis to specify the mathematical model. The experimental results show that this mathematical model allows quantitative estimation of rat sociality. Likewise, the results reveal that rat sociality can be analyzed and modified in this robot-rat interaction system.

Neurologic examination takes an important role in diagnosis of the nerve system diseases. Neurologic medical staffs, especially the novices, need to be trained on this skill. There are many methodologies which can help to accumulate experiences, such as watching video, reading books, making use of the simulated patient (SP), and so on. However, the best way is to practice on the real patient. All the above methods have their own drawbacks such as lack of active interactions, limitation of multi-symptoms' reproducing, etc. To improve the training effectiveness, an arm robot is proposed in this paper for neurologic examination training as one part of the whole body patient robot named Waseda Kyotokagaku Patient (WKP). In this robot, various symptoms of the elbow force, biceps tendon reflex, involuntary action, and so on, are simulated and shown to the trainee. Finally, a set of experiments was carried out to verify our proposed mechanism and control system. Three neurologists with over 30 years' experience were invited to show their opinions on the reproductions of patients' symptoms, and to discuss the results. The effectiveness of this system was confirmed. The experimental results lead to the consideration that the approach is worth following in further research.

In this work we propose an adaptive model for the head stabilization based on a feedback error learning (FEL). This model is capable to overcome the delays caused by the head motor system and adapts itself to the dynamics of the head motion. It has been designed to track an arbitrary reference orientation for the head in space and reject the disturbance caused by trunk motion. For efficient error learning we use the recursive least square algorithm (RLS), a Newton-like method which guarantees very fast convergence. Moreover, we implement a neural network to compute the rotational part of the head inverse kinematics. Verification of the proposed control is conducted through experiments with Matlab SIMULINK and a humanoid robot SABIAN.

This paper describes a fast turning method for a humanoid robot by using slipping motion with both feet. The humanoid robot, WABIAN-2R, has achieved human-like walking with heel contact and toe off motions by using a human-like foot mechanism with a passive toe joint. The human-like foot enables a robot to turn by using slipping motion between the feet and the ground because it can switch ground contact conditions such as heel contact, sole contact and toe contact. To realize a slipping turn, we develop an attitude control. Verification of the proposed method is conducted through experiments with a biped humanoid robot WABIAN-2R. WABIAN-2R realized a quick turn by using slipping motion with both feet. We also confirmed that the energy consumption of a slipping turn is less than that of a stepping turn.

Performing laparoscopic surgery requires several skills which have never been required for conventional open surgery, surgeons experience difficulties in learning and mastering these techniques. Various training methods and metrics have been developed in order to assess and improve surgeon's operative abilities. While these training metrics are currently widely being used, skill evaluation methods are still far from being objective in the regular laparoscopic skill education. This paper proposes a methodology of defining a model to objectively evaluate surgical performance and skill expertise in the routine laparoscopic training course. Our approach is based on the processing of kinematic data describing the movements of surgeon's upper limbs. An ultra-miniaturized wearable motion capture system (Waseda Bioinstrumentation system WB-3), therefore, has been developed to measure and analyze these movements. The skill evaluation model was trained by using the subjects' motion features acquired from WB-3 system and further validated to classify the expertise levels of the subjects with different laparoscopic experience. An experiment for training fundamental laparoscopic psychomotor skill was elaborated by using laparoscopic box trainer. Preliminary results show that, the proposed methodology can be efficiently used both for quantitative assessment of surgical ability, and for the discrimination between expert surgeons and novices.

Up to now, there are different kinds of robot-assisted ultrasound diagnostic systems proposed in the last decade. However, the compensation of the ultrasound probe position according to the patient movement is still one of the most important and useful functions required for those systems. For this purpose, in this research, we aim at developing an automated diagnostic system for the measurement of the wave intensity which is usually measured at the common carotid artery. In particular, in this paper, we focus on proposing a robust visual servoing method for tracking out-of-plane motion for a robot-assisted medical ultrasound diagnostic system by using a conventional 2D probe. A robotic device which manipulates the ultrasound probe firstly scans a small area around the target position and records several B-mode images at a regular interval. In order to track the out-of-plane motion, an inter-frame block matching method has been proposed and implemented on the Waseda-Tokyo Women's Medical-Aloka Blood Flow Measurement System No. 2 Refined (WTA-2R). A set of experiments was proposed to verify the effectiveness of the proposed method. From the experimental results, we could confirm its robustness while doing the task with real human tissues.

In recent years advanced robotic technology has seen more use in the medical field to assist in the development of efficient training systems. Such training systems must fulfill the following criteria: they must provide quantitative information, must simulate the real-world conditions of the task, and assure training effectiveness. We developed Waseda Kyotokagaku Airway series to fulfill all of those requirements. The WKA series we had developed does not consider external appearance such as patient skin, or internal appearance such as the pharynx, larynx, and esophagus. Moreover, the tongue mechanism of the previous system can not precisely measure the force applied by medical devices and cannot simulate muscle stiffness. In addition, the mandible mechanism of the previous system could not adequately reproduce various airway difficulties or apply force control. For these reasons, we propose the WKA-4, which has high-fidelity simulated human anatomy, and we have improved the mechanism over the previous system. We have also attached a lung to the proposed system to improve simulation of the real-world conditions of the task. In this paper, we present how to design several organs with various embedded sensors and actuators, for a conventional patient model with high-fidelity simulated human anatomy. We also present the control system for the WKA-4. Finally, we present a set of experiments carried out using doctors as subjects, and they gave their valuable opinions about our system.

Many patients suffer from swallowing disorders (dysphagia). There are many treatments for these disorders, such as swallowing therapy, surgery, and dietary modification. In our study, we focuse on dietary modification, a common approach. Normally, the swallowing is affected by food bolus properties such as hardness, stickiness and rheological characteristics, and dietary modifications can prevent swallowing disorder patients from suffering dysphagia (aspiration), as well as promote good nutrition. Based on these facts, our goal is to find foods which do not cause dysphagia, and develop food for swallowing disorder patients accordingly. Therefore, we are proposing an in-vitro Dynamic VFSS (Video Fluorographic Swallowing Study) simulation system which uses advanced robotics technology to mimic the dynamic process of swallowing and monitors the status and movement of the food bolus inside the system, for objective evaluation of the swallowing process. The dynamic VFSS simulation system consists of a head, mandible, neck, tongue, pharynx, and larynx which reproduce human anatomy. It is driven by 16 actuators with wire driving mechanisms. In this paper, we will present the dynamic VFSS simulation unit in detail. In addition, we will detail a set of the experiments carried out to determine whether food bolus properties can affect dysphagia or not. To observe the movement of the food bolus, we use a Video Fluoroscopy (VF) unit. The results of the experiments show that thickened boluses have a tendency to leave residue in the epiglottic vallecula. In contrast, liquids cause less residue, and increase the risk of dysphagia (aspiration). Moreover, this study shows that the frontal image, as well as the lateral image, is important for evaluating residual food in the oral- pharyngeal space.

Our research is related to the development of an anthropomorphic saxophonist robot which reproduced the human organs involved during the saxophone playing. This research approach aims in understanding the human motor control from an engineering point of view and enabling the communication between humans and robots in musical terms. In a previous research, we have presented the Waseda Saxophonist Robot No. 2 (WAS-2) which improved the design of the lip and finger mechanisms. In addition, a feed-forward air pressure with dead-time compensation and an overblowing correction controller were implemented. However, the range of pressure was too limited to reproduce dynamic effects of the sound (i.e. decrescendo, etc.), a delay on the response of the finger mechanism was detected (due to the use of a wire-driven mechanism) and deviations on the pitch during the saxophone playing were observed. Therefore; in this paper, we present the Waseda Saxophonist Robot No. 2 Refined (WAS-2R). In particular the shape of the oral cavity has been re-designed to increase the sound pressure range and potentiometers were embedded on the fingers to reduce the dynamic delay response of the wire-driven mechanism. In addition, a Pressure-Pitch Controller has been implemented to reduce the deviation of the sound pitch by implementing a feedback error learning algorithm for a Multiple-Input Multiple-Output system. A set of experiments were proposed to verify the effectiveness of the re-designed mechanisms and the improved control strategy. From the experimental results, we could confirm the improvements to extend the sound pressure range to reproduce the decrescendo effect, to reduce the response delay from the finger mechanism as well as the deviations on the sound pitch.

A four degrees of freedom (DoF) waist and trunk mechanism, as well as human-like foot, enable the humanoid robot WABIAN-2R to perform human-like walk with stretched knees, and heel-contact and toe-off gait phases. The inverse kinematics (IK) method, used in the present system, requires specification of not only task space reference trajectories, but also reference trajectories for all redundant DoFs. In this paper, we propose a novel, unified inverse kinematics method significantly simplifying the pattern generation. The method enables generation of the above described gait by specifying only the task space trajectories. We divide the forward locomotion task into subtasks with different priorities and combine them in the single IK equation. We also perform experiments in simulation environment as well as on WABIAN-2R, which prove that the method can be used to calculate IK for human-like gait. The equation evaluated in this paper is applied to the forward locomotion task, however it can be easily modified to perform other tasks on humanoid robots with different kinematic structures.

In this paper we propose the basic concept of a tele-presence system for two (or more) anthropomorphic robots located in remote locations. As one robot interacts with a user, it acquires knowledge about the user's behavior and transfers this knowledge to the network. The robot in the remote location accesses this knowledge and according to this information emulates the behavior of the remote user when interacting with its partner. The behavioral patterns are grouped into macro-behavior units (maBUs) and mirco-behavior units (miBUs). maBUs carry information that is specific to a person-to-person communication. miBUs are commonly used behavior patterns within a certain cultural environment (e.g. handshake, bow etc). maBUs are usually chains of miBUs. miBUs are chains of expression actions (e.g. gesture, facial expression etc.). The idea behind this is, that human communication contains several levels or layers of information exchange. This to be emulated by implementing the concept of miBUs and maBUs. We present a preliminary application of this concept to a musical context. The rhythmic motion of a drum-stick during the performance of a drum rhythm by a musician is recorded by a inertial measurements unit and transmitted between two far distance locations (Waseda University in Japan and Karlsruhe Institute of Technology in Germany) using three different transmission methods: direct raw data transmission, miBU based transmission and maBU-based transmission. We present experimental results that show quantitative data to evaluate the suitability of our approach, with the overall goal to implement a telepresence system of larger scale.

This paper describes an avoidance behavior from unknown external forces for a biped walking vehicle. To distinguish between external forces from passenger and those from environments, we use the data of a force sensor mounted on foot, and external forces are estimated from ZMP errors. To guarantee a walking stability, the waist position is adjusted to match the measured ZMP to the reference ZMP, and the position of landing foot is adjusted so that the waist trajectory does not diverge. By implementing the developed method on the human-carrying biped robot, the robot realized a stable walk under unknown external forces from environments. When pushing the robot stepping, the robot moved backward and moved away from the generation source of external forces about 400 mm. When pushing the robot walking forward, the robot stopped going forward and prevented from coming closer to the generation source of external forces. We confirmed the effectiveness of the proposed control through these experiments.

We have developed a new biped foot mechanism capable of detecting ground surface to realize stable walking on uneven terrain. The size of the foot mechanism is 160 mm × 277 mm and its weight is 1.5 kg. The foot system consists of four spikes each of which has an optical sensor to detect ground height. The foot makes a support polygon on uneven terrain by using three or four spikes. We have conducted several experiments on the outdoor ground surface that has a slope of 7.0 degrees and a maximum height of 15 mm bumps, and the effectiveness of the foot mechanism is confirmed.

Since 2007, the research on the anthropomorphic saxophonist robot at Waseda University aims in understanding the human motor control from an engineering point of view as well as an approach to enable the interaction with musical partners. As a result of our research, last year we have introduced the Waseda Saxophonist Robot No. 1 (WAS-1), composed of 15-DOFs that reproduced the lips (1-DOF), tonguing (1-DOF), oral cavity, lungs (2-DOF) and fingers (11-DOFs). However, even that the mouth mechanism of WAS-1 was useful in order to adjust the pitch of the saxophone sound, the range of sound pressure was too narrow. Thus, no dynamic effects of the sound can be reproduced (i.e. crescendo and decrescendo). Moreover, the finger mechanism was designed only to play from C3-C#5. On the other hand, a cascade feedback control system has been implemented in the WAS-1; however, a considerable delay in the attack time to reach the desired air pressure was detected. Therefore, in this paper, the Waseda Saxophone Robot No. 2 (WAS-2) which is composed by 22-DOFs is detailed. The lip mechanism of WAS-2 has been designed with 3-DOFs to control the motion of the lower, upper and sideway lips. In addition, a human-like hand (16 DOF-s) has been designed to enable to play all the keys of the instrument. Regarding the improvement of the control system, a feed-forward control system with dead-time compensation has been implemented to assure the accurate control of the air pressure. A set of experiments were carried out to verify the mechanical design improvements and the dynamic response of the air pressure. As a result, the range of sound pressure has been increased and the proposed control system improved the dynamic response of the air pressure control.

The humanoid robot, WABIAN-2R, has achieved human-like walking with knee-stretched, heel contact and toe off motions by using a foot mechanism with a passive toe joint. However, the foot structure is different from a human's. In this paper, we describe a new foot mechanism capable of mimicking the human's foot arch structure to figure out the function of the arch structure. Especially, the developed foot mimics the elastic properties of the arch of the human's foot and the change of the arch height during walking. The foot mechanism consists of a passive joint in the internal toe, a passive joint in the external toe, and a joint in the foot arch. We conducted several walking experiments by using WABIAN-2R, and the function of the arch structure is clarified quantitatively. As a result, we confirmed that the arch elasticity could absorb a foot-landing force at the plantar contact phase and the change of the arch height contributed to a strong thrust at the push-off phase.

The number of patients with mental disorders is increasing in advanced countries. Many researchers are working to develop mental disorder model animals that contribute to development of new psychotropic drugs. However, we have some doubts about conventional mental disorder models. Therefore, the purpose of this study is to develop an experimental setup to create novel mental disorder model animals. We then developed a small mobile robot and a control system for the robot. Using them, we performed an experiment to develop a mental disorder model rat. In the experiment, we succeeded in developing a new depression model rat and also high activity model rat. These disorder models must be useful in the screening of new psychotropic drugs. In addition, the methodology we developed in this research will contribute to clarifying mechanisms of mental disorders.

In this paper, we present a robotic system which automatically searches and detects the longitudinal section of the carotid artery using a conventional medical ultrasound diagnostic system. In order to obtain a clear image of the carotid artery ready for medical diagnosis, the authors developed real-time image processing algorithms to detect the carotid artery and tissue layers of its walls in the B-mode ultrasound images. Sequential patterns of the ultrasound probe trajectory for scanning the surface of the neck and searching the carotid, were implemented and tested on the Waseda-Tokyo Women's Medical-Aloka Blood Flow Measurement Robot System No. 1 Refined II (WTA-1RII). An experiment with eleven volunteers was carried out and the results show that the system obtained clear images of the carotid artery in 91% of the trials.

Recently, in medical field, different training methods for medical staff have been proposed. However, the lack of knowledge on the real improvements of trainees makes difficult the real effectiveness of those proposed methods. Therefore, we are proposing an Active Training system for the effective medical training. The Active training system is characterized by providing quantitative information of the trainee's performance of the task to the trainee, simulating real-world conditions of the task, and assuring training effectiveness. In order to fulfill each of these characteristics, we have developed Waseda Kyotokagaku Airway No.3 (WKA-3) which makes it possible to obtain quantitative information for the trainee's performance and reproduce the various cases, individual differences for the airway difficulties for the simulating real-world conditions of the task. In this paper, we are proposing a patient scenario generation which can reproduce the characteristics of the patient simulating real-world conditions of the task for WKA-3. In emergent situation or surgical operation, the characteristics of patients are presented in the three parameters such as: patient initial conditions, time variant status change, and reflex action. By adjusting, and combining each of the three parameters, we can reproduce the various patient scenarios. In this paper, we also state how to generate the Patient Scenario Generation using the position control and virtual compliance control. Finally, a set of experiments has been carried out to the doctor subjects in order to verify effectiveness of the proposed Patient Scenario Generation, and discuss the doctors about the result of the experiments.

An active training system is characterized by providing quantitative information of the trainee's performance of the task to the trainee, simulating real-world conditions of the task, and assuring training effectiveness. For this purpose, the authors have been developing an Airway management training system. In particular, we have previously presented an evaluation model system to acquire quantitative information for the trainee's performance, and an actuated model system for real-world conditions of the task. In order to fulfill all of the characteristics of the active training system; in this paper, we would like to propose an integrated system, Waseda Kyotokagaku Airway No.3 (WKA-3) which integrates the function of both system models. For this reason, we have focused on embedding sensors and actuators with the link drive mechanism and the wire drive mechanism to a conventional patient model towards the development of a patient robot. In this paper, we present WKA-3 how to design the mechanism and how to redesign several organs to embed the sensors for the measurement of the trainee's performance. A set of experiment have been carried out to doctor subjects using the WKA-3 to verify the effectiveness of the proposed system by asking doctors to evaluate the proposed system.

The flutist robot WF-4RIV at Waseda University is able to play the flute at the level of an intermediate human player. So far the robot has been able to play in a statically sequenced duet with another musician, individually communicating only by keeping eye-contact. To extend the interactive capabilities of the flutist robot, we have in previous publications described the implementation of a Music-based Interaction System (MbIS). The purpose of this system is to combine information from the robot's visual and aural sensor input signal processing systems to enable musical communication with a partner musician. In this paper we focus on that part of the MbIS that is responsible for mapping the information from the sensor processing system to generate meaningful modulation of the musical output of the robot. We propose a two skill level approach to enable musicians of different ability levels to interact with the robot. When interacting with the flutist robot the device's physical capabilities / limitations need to be taken into account. In the beginner level interaction system the user's input to the robot is filtered in order to adjust it to the state of the robot's breathing system. The advanced level stage uses both the aural and visual sensor processing information. In a teaching phase the musician teaches the robot a tone sequence (by actually performing the sequence) that he relates to a certain instrument movement. In a performance phase, the musician can trigger these taught sequences by performing the according movements. Experiments to validate the functionality of the MbIS approach have been performed and the results are presented in this paper.

In the domain of psychology and medical science, many experiments have been conducted referring to research on animal behaviors, to study the mechanism of mental disorders and to develop psychotropic drugs to treat them. Rodents such as rats are often chosen as experimental subjects in these experiments. However, according to some researchers, the experiments on social interactions using animals are poorly- reproducible. Therefore, we consider that the reproducibility of these experiments can be improved by using a robotic agent that interacts with an animal subject. We have developed a novel quadruped rat-inspired robot, the WR-2 (Waseda Rat No.2), based on the dimension and body structure of a mature rat. It is capable of reproducing the behaviors such as walking, mounting, rearing and grooming of the rat.

Since 2007, our research is related to the development of an anthropomorphic saxophonist robot, which it has been designed to imitate the saxophonist playing by mechanically reproducing the organs involved for playing a saxophone. Our research aims in understanding the motor control from an engineering point of view and enabling the communication. In a previous paper, the Waseda Saxophone Robot No. 2 (WAS-2) which is composed by 22-DOFs has been presented. Moreover, a feedback error learning with dead time compensation has been implemented to control the air pressure of the robot. However, such a controller couldn't deal with the overblowing effects (unsteady tones) that are found during a musical performance. Therefore; in this paper, the implementation of an Overblowing Correction Controller (OCC) has been proposed and implemented in order to assure the steady tone during the performance by using the pitch feedback signal to detect the overblowing condition and by defining a recovery position (off-line) to correct it. Moreover, a saxophone sound evaluation function (sustain phase) has been proposed to compare the sound produced by human players and the robot. A set of experiments were carried out to verify the improvements on the musical performance of the robot and its sound has been quantitatively compared with human saxophonists. From the experimental results, we could observe improvements on the pitch (correctness) and tone stability.

Personal robots anticipated to become popular in the future are required to be active in joint work and community life with humans. These personal robots must recognize changing environment and must conduct adequate actions like human. Visual tracking can be said as a fundamental function from the view point of environmental sensing and reflex reaction against it. The authors developed a visual tracking motion algorithm by using upper body. Then, we integrated it with an online walking pattern generator and developed a visual tracking biped locomotion. Finally, we conducted an experimental evaluation with emotion expression.

The research on Music Playing-Instrument Humanoid Robots (MP-HRs) has a long tradition in the research field of robotics since the development of the humanoid pianist robot WABOT-2 developed at Waseda University (1984). Since then, several researchers have been aiming for the better understanding of the human musical performance. For this purpose, different mechanical designs and cognitive functions have been implemented on them. A particular interest was given to wind instruments as a research approach for understanding human breathing mechanism. Nowadays, different kinds of automated machines and humanoid robots have been developed for playing wind instruments to understand the human motor control from an engineering point of view. Moreover, the importance of studying the ways of enabling the interaction between musicians-humanoid is being attracting several researchers from different research fields. As a long-term research goal, we are aiming to enable wind playing-instrument humanoid robots to display motor dexterities and high-level perceptual capabilities to interact with other musician partners. In this paper, we present our current research achievements on the development of an anthropomorphic saxophonist robot and the implementation of a musical-based interaction system tested on an anthropomorphic flutist robot.

Personal robots and robot technology (RT)-based assistive devices are expected to play a major role in our elderly-dominated society, by interacting with surrounding people both physically and psychologically. A fundamental role during the interaction is of course played by the hand. In this paper we present the evaluation of the effect of hand shape to the quality of the interaction, in particular during handshake.

The emerging field of medical robotics aims to introduce intelligent tools to assist a physician. The main challenges for developing efficient medical robotic training systems are simulating real-world conditions of the task and assuring training effectiveness. High anatomic fidelity has been achieved in current systems. However, those training systems are designed to reproduce specific conditions of the task (passive training). In this research, we are focusing in developing an airway management training systems designed to reproduce various cases of difficult airway. Such difficulties (i.e. restricted mouth opening, various shapes of oral cavity including tongue swallowing, etc) may provoke traumas on different organs of the patient during an emergency situation. For this purpose, the authors have proposed the development of more advanced training tools. For this purpose, we have focused in embedding sensors and actuators to a conventional patient model towards the development of a patient robot (in previous research, authors have presented the evaluation model which embeds sensors). In this paper, we present an airway training system which embeds actuators into a mannequin. In particular, the mechanism design of the Waseda Kyotokagaku Airway No.2 (WKA-2) is detailed. The WKA-2 is composed of twelve active and one passive degrees of freedom; which are designed to reproduce the various cases of difficult airway. For this purpose, the WKA-2 reproduces the human muscles around the upper airway based on a wire driving mechanisms (a total of sixteen wires are used). In particular, the head of the model is composed of a tongue and mandible with translational and rotational movements around kinematic axis. In addition, we present the details of the kinematic model of WKA-2 which enable the robot to reproduce the airway difficulties. Finally, we presented the design of a tension sensor designed to measure the applied tension on each of the wire driving mechanism of WKA-2. As preliminary experiments, we reproduce several cases of difficult airways using WKA-2.

The research on the development of musical performance robots has been particularly intensified on the last decades. In fact, the development of anthropomorphic robots able of playing musical instruments have been served as a mean for understanding the human motor control from an engineering point of view as well as understanding how to enable the communication between human and robots from an emotional point of view. In particular, our research aims in the development of an anthropomorphic saxophonist robot which is able not only of performing a musical score; but also to interact with other musical performance robots (i.e. Waseda Flutist Robot) at the emotional level of perception. In this year, we have focused on the mechanical design of an anthropomorphic robot Waseda Saxophonist Robot No. 1 (WAS-1); which has been designed for playing an alto saxophone. WAS-1 has a total of 15-DOFs which mechanically reproduces the following organs involved during the saxophone playing: lips (1-DOF), tongue (1-DOF), oral cavity, lungs (air pump: 1-DOF and air valve: 1-DOF) and fingers (11-DOFs). In order to verify the effectiveness of the production of sound, a set of experiments have been proposed. In particular, the characteristics of air flow-pressure, level of mechanical noise, and the ripple effect ratio are presented. Finally, a qualitative evaluation of the sound produced by WAS-1 is presented and discussed. From the experimental results, we have confirmed the effectiveness of the proposed mechanisms to produce the saxophone sound.

The emerging field of medical robotics is aiming in introducing intelligent tools to perform medical procedures. In particular, robotic researchers have been proposed advanced medical training systems to enhance motor dexterities of trainees. An efficient medical training system should be designed to simulate real-world conditions and to assure their effectiveness as the representation of the motor skills often differs among trainees. Up to now, several training simulators have been developed by medical companies designed to reproduce with high fidelity the human body. However, such devices are not designed to provide any information to trainees. Therefore, we have proposed the development of a patient robot which embeds sensors and actuators into a conventional human model. Due to its complexity, as a first approach; we are presenting the development of a suture training system designed to simulate the real-world task conditions as well as providing quantitative assessments. In particular; the Waseda-Kyotokagaku Suture No.2 Refined II is presented, which includes a new evaluation function to provide more detailed information of the task. A set of experiments were proposed to analyze the performance of trainees. From the experimental results, we could confirm its effectiveness to detect differences of the performance of trainees.

We have developed a new, three dimensional vocal tract mechanical model for an anthropomorphic talking robot WT-7R (Waseda Talker No. 7 Refined), to improve the resonance of the vocal tract. The Waseda Talker robot series aims to reproduce the human speech mechanism with three-dimensional accuracy. The tongue of the previous model, WT-7 (Waseda Talker No. 7), was made of rigid links and covered with a thermoplastic rubber (Septon). This mechanism could deform the tongue shape and work as a part of the vocal tract, however, the cover thickness was not sufficient enough to prevent sound leakage, and did not have sufficient resonance. As a result, the produced sounds were unclear. To resolve this problem, the inner area of the tongue was filled with liquid. We experimented to select the filling liquid which is minimizes damage to the Septon cover and provides adequate resonance characteristics. The ethylene glycol was selected because it does little damage to the Septon and is relatively non-flammable. An oil seal and liquid gasket prevent leakage into the robot. WT-7 also has problems with its tongue link deformation range and open lip control range-these problems were also addressed. The improvements made the vowel production of WT-7R clearer than that of the previous robot, and the bandwidth of the formant peak in spectral analysis became sharper.

Many researchers have studied on walking stability controls for biped robots. Most of them are highly accurate acceleration controls based on the mechanics model of the robot. However, the control algorithms are difficult to be applied to human-carrying biped robots due to modeling errors. In the previous report, we proposed the landing pattern modification method, but it had a problem that a foot landing impact increased when a walking speed became fast. So, we propose a new terrain-adaptive control that can reduce a landing- impact force. To increase a concave terrain adaptation, we set a target landing position beneath a reference level. To reduce the landing-impact force, we change the position gain control value to a small value at a swing phase. Moreover, we set landing-foot speed at zero after detecting a foot-landing by the force sensor mounted on a foot. To follow uneven terrain, a virtual spring is installed to the vertical direction after detecting a foot-landing on a ground, and a virtual compliance control is applied to the roll and pitch axes. In a stable walk while carrying a 65 kg human on uneven terrain, the new control method decreased the landing-impact force than the previous terrain-adaptive control.

In recent years, due to the increasing rate of elderly people in Japan, the needs to detect adults' diseases at the early stage becomes a high priority. In particular, an increased interest in detecting heart and cerebrovascular diseases at an early stage may allow clinicians to begin treatment sooner, when interventions are generally more effective and less expensive. Recently, the wave intensity (WI) has been proposed as a new hemodynamic index that provides information about the dynamic behavior of the heart and the vascular system and their interaction. However; the repetitiveness and accuracy of the WI measurement depend on the precision of the positioning of the ultrasound probe. Therefore a positioning device for ultrasound probe is required. Such a device should not only be used to keep the position but also for the fine positioning of the probe. For this purpose, at Waseda University, we have proposed the development of a robot system to assist a carotid blood flow measurement using ultrasound diagnostic equipments. In this paper, the development of Waseda-Tokyo Women's Medical-Aloka Blood Flow Measurement System No. 1 Refined II (WTA-1RII) is detailed. The system consists of an ultrasound diagnostic device, a 6-DOFs parallel link manipulator, a serial link passive arm, ball joint, and a joystick type controller. The WTA-1RII has improved the design of the gravity compensation mechanism. In addition, a genetic algorithm has by implemented to determine the optimal link's position of the 6-DOFs parallel manipulator to increase the workspace. Finally, a set of experiments were carried out to determine the usability of the proposed system.

The Waseda flutist robot is able to play the flute at the level of an intermediate human player. This ability opens a wide field of possibilities to research human-robot musical interaction. This research is focused on enabling the flutist robot to interact more naturally with musical partners in the context of a Jazz band. For this purpose a musical-based interaction system (MbIS) has been proposed to enable the robot to process both visual and aural cues coming throughout the interaction with musicians. In a previous publication, we have concentrated on the implementation of visual communication techniques. We created an interaction interface that enabled the robot to detect instrument gestures of partner musicians during a musical performance. Two computer vision approaches were implemented to create a two-skill-level interface for visual human-robot interaction in a musical context. In this paper we focus on the aural perception system of the robot. The method introduced here enables the robot to, a suitable environment provided, detect the tempo and harmony of a partner musician's play, with a specific focus on improvisation. We achieve this by examining the rhythmical and harmonic characteristics of the recorded sound. We apply the same approach to amplitude and frequency spectrum, thus, in the former case tracking amplitude transients. In the latter case, as we focus on communication with monophonic woodwind instruments, we follow the most prominent peak in the frequency spectrum. We specifically use a similar technique for the audio analysis as we did for our previous research on motion tracking. From the experimental results, we have shown that after implementing our algorithm the robot is able to correctly recognize a number of rhythms and harmonies. It is able to engage in a simple form of stimuli and reaction play with a human musician.

In recent years there has been an ever increasing amount of research and development of technologies and methods to improve the quality and the performance of advanced surgery. In other fields several training methods and metrics have been proposed, both to improve the surgeon's abilities and also to assess her/his skills. For neurosurgery, however, the extremely small movements and sizes involved have prevented until now the development of similar methodologies and systems. In this paper we present the development of an ultra-miniaturized Inertial Measurement Unit and its application for the evaluation of the performance in a simple pick and place scenario. This analysis is a preliminary yet fundamental step to realize a better training/evaluation system for neurosurgeons, and to objectively evaluate and understand how the neurosurgery is performed.

The rapidly increase of personal robotic platforms and their applications in Japan represents a great challenge for universities to introduce undergraduate students the basic knowledge required to develop intelligent automated mechanisms. For this purpose; in this paper, we are presenting our approach to introduce first year undergraduate students of the Department of Modern Mechanical Engineering the basics of robotics systems. In order to foster the creativity of undergraduate students of engineering fields, we focused in developing an education tool designed to introduce at different educational levels the principle of developing mechatronic systems. In particular, the development of an inverted pendulum mobile robot Waseda Wheeled Vehicle No. 2 (WV-2R) has been proposed. Different kinds of experiments were proposed to confirm the possibility of implementing controllers as well as changing physical properties of the system to observe differences on the response of the system. From the experimental results, we could confirm the effectiveness of the proposed systems to control the angle of pendulum respect to the body base as well as by changing the radius of the wheel.

During several decades, the research at Waseda University has been focused on developing anthropomorphic robots able of performing musical instruments. More recently, the authors have succeeded in developing a human-like robot able of playing the alto saxophone. As a result of our research efforts, the Waseda flutist robot WF-4RIV and the Waseda saxophonist robot WAS-1 have been designed to reproduce the human player performance. Therefore, as a long-term goal, we are proposing to enable the interaction between musical performance robots (i.e. robots orchestra). Such approach may enable us not only to propose new ways of musical expression, but also we may contribute to the better understanding of some of the mechanisms that enable the communication of humans in musical terms. In general terms, the communication of humans within an orchestra is a special case of conventional human social behavior. Rhythm, harmony and timbre of the music played represent the emotional states of the musicians. Of course, we are not considering a musical performance robot (MPR) just as a mere sophisticated MIDI instrument. Instead, its human-like design and the integration of perceptual capabilities may enable to act on its own autonomous initiative based on models which consider its own physical constrains. Due to the complexity of our long-term goal, in this paper, we are presenting our first steps towards enabling the interaction between musical performance robots. In particular, the details of the musical performance control systems are detailed. Thanks to the use of MIDI data, we performed preliminary experiments to enable a duet performance between the WF-4RIV and the WAS-1. We expect in the future; as a result of our research, we may enable a single anthropomorphic robot to perform different kinds of woodwind instruments as well as enable to interact at with level of perceptual capabilities (like human does).

The rapidly increase of personal robotic platforms and their applications in Japan represents a great challenge for universities to introduce undergraduate students the basic knowledge required to develop intelligent automated mechanisms. For this purpose; in this paper, we are presenting our approach to introduce first year undergraduate students of the Department of Modern Mechanical Engineering the basics of robotics systems. In particular, the details of curricula of the Mechatronics Laboratory (1) and (2) are explained. In both lessons, the students receive lectures of the content of each proposed topic and then, a set of practical experiments are done. On the other hand, in order to foster the creativity of undergraduate students of engineering fields, we focused in developing an education tool designed to introduce at different educational levels the principle of developing mechatronic systems. In particular, the development of an inverted pendulum mobile robot Waseda Wheeled Vehicle No. 2R (WV-2R) has been proposed. Regarding the Mechatronics Laboratory, questionnaires were proposed to obtain information from the students about their impressions of the lessons. From the comments collected from the questionnaires, we observed the advantages of the proposed curricula to introduce them about robot technology. On the other hand, different kinds of experiments were proposed to confirm the possibility of implementing controllers as well as changing physical properties of the system to observe differences on the response of the system.

The rapidly increase of personal robotic platforms and their applications in Japan represents a great challenge for universities to introduce undergraduate students the basic knowledge required to develop intelligent automated mechanisms, by introducing in simple and efficient ways the basic components of robots as well as their application for solving real-world problems. In Japan, the proliferation of amateur robot contests has been introduced to motivate their interest to get involved in the robotics field. This is not only the case for tournaments supported by local governments and private companies. Several universities along Japan have been implementing Project-Based Learning (PBL) within their curricula as introduction for Mechatronic. For this purpose, at Waseda University, we focused in developing an education tool designed to introduce at different educational levels the principle of developing mechatronic systems. In particular, the development of an inverted pendulum mobile robot Waseda Wheeled Vehicle No. 2 (WV-2R) has been proposed. In this paper, an overview of the research results is detailed. Even that in many universities around the world has been promoting the introduction of robotic technology, little discussion has been done to analyze from an ethical point of view. In this paper, some issues related to both Robot Education and Engineering Ethical Education are give based on experiences carried out in Japan. Then, some points regarding the integration of RoboEthics Education are pointed out for discussion.

Personal robots and robot technology (RT)-based assistive devices are expected to play a major role in our elderly-dominated society, with an active participation to joint works and community life with humans, as partner and as friends for us. In particular, these robots are expected to be fundamental for helping and assisting elderly and disabled people during their activities of daily living (ADLs). To achieve this result, personal robots should be also capable of human-like emotion expressions. To this purpose we developed a new whole body emotion expressing bipedal humanoid robot, named KOBIAN, which is also capable to express human-like emotions. In this paper we presented three different evaluations of the emotional expressiveness of KOBIAN. In particular In particular, we presented the analysis of the roles of the face, the body, and their combination in emotional expressions. We also compared Emotional patterns created by a Photographer and a Cartoonist with the ones created by us. Overall, although the experimental results are not as good as we were expecting, we confirmed the robot can clearly express its emotions, and that very high recognition ratios are possible.

Personal robots and robot technology (RT)-based assistive devices are expected to play a major role in our elderly-dominated society, with an active participation to joint works and community life with humans, as partner and as friends for us. The authors think that the emotion expression of a robot is effective in joint activities of human and robot. In addition, we also think that bipedal walking is necessary to robots which are active in human living environment. But, there was no robot which has those functions. And, it is not clear what kinds of functions are effective actually. Therefore we developed a new bipedal walking robot which is capable to express emotions. In this paper, we present the design and the preliminary evaluation of the new head of the robot with only a small number of degrees of freedom for facial expression.

Up to now, there is no widely accepted quantitative evaluation scheme. Nowadays, an objective structured clinical examination has been proposed as a modern type of examination often used in medicine to test skills such as medical procedures, etc. The assessment of skills is realized by practical exams, in which students are evaluated by experienced examiner using a check list. However, the examiner lacks of information which cannot be obtained trough the simple observation of the task. Thanks to the advances in robot technology in embedded systems, etc.; more advanced evaluation tools can be conceived. For this reason, at Waseda University, we have proposed the development of a patient robot as an advanced evaluation tool to provide more detailed information of the task. As a first approach of our long-term research target, we have proposed the development of a suture/ligature training system which provides quantitative information of the movement of a dummy skin as well as information of the quality of task. In this paper; we describe the functionalities of the newest version, the Waseda-KyotoKagaku Skin No.2 Refined (WKS-2R), which has been designed to provide quantitative information of the task. In addition, we are proposing a new evaluation function which includes performance indexes and weighting coefficients. As a first approach, the weighting coefficients were determined by using the discriminant analysis. A set of experiments were proposed to confirm the effectiveness of the proposed evaluation function. From the preliminary results, the evaluation function was useful in detecting differences among different levels of expertise as well as detecting improvements during the training process by computing the learning curve.

Up to now, different kinds of musical performance robots (MPRs) and robotic musicians (RMs) have been developed. MPRs are designed to closely reproduce the motor skills displayed by humans in order to play musical instruments. From this approach, MPRs are used as benchmarks to study the human motor control from an engineering point of view and to understand better the human-robot interaction from a musical point of view. In contrast, RMs are conceived as automated mechanisms designed to create new ways of musical expression from a musical engineering point of view. Our research, at Waseda University, has been focused on developing an anthropomorphic flutist robot. Our research aims in studying the human motor control from an engineering point of view, understanding the ways to facilitate the human-robot interaction and proposing new applications for humanoid robot in musical terms. As a result of our research, the Waseda Flutist Robot No.4 Refined IV (WF-4RIV) has been developed. In a previous research, we focused on improving the mechanical system in order to enhance the clarity of the sound. However, we require performing further improvements to the control system in order to enable the robot to autonomously improve the quality of the sound during the flute performance. For this purpose, we proposed to implement an auditory feedback control system on the flutist robot. The proposed system is composed by a music expressive generator, feed-forward air pressure control system and a pitch evaluation module. From the experimental results with the WF-4RIV, we could confirm the improvements on the flute performance.

The aim of this paper is to create an interface for human-robot interaction. Specifically, musical performance parameters (i.e. vibrato expression) of the Waseda Flutist Robot No.4 Refined IV (WF-4RIV) are to be manipulated. Our research is focused on enabling the WF-4RIV to interact with human players (musicians) in a natural way. In this paper, as a first approach, a vision processing algorithm, that is able to track the 3D-orientation and position of a musical instrument, was developed. In particular, the robot acquires image data through two cameras attached to its head. Using color histogram matching and a particle filter, the position of the musicianpsilas hands on the instrument are tracked. Analysis of this data determines orientation and location of the instrument. These parameters are mapped to manipulate the musical expression of the WF-4RIV, more specifically sound vibrato and volume values. We present preliminary experiments to determine if the robot may dynamically change musical parameters while interacting with a human player (i.e. vibrato etc.). From the experimental results, we may confirm the feasibility of the interaction during a performance, although further research must be carried out to consider the physical constraints of the flutist robot.

Our research aims to develop an anthropomorphic flutist robot as a benchmark for the better understanding of interaction between musicians and musical performance robots from a musical point of view. As a long-term goal of our research, we would like to enable such robots to play actively together with a human band, and create novel ways of musical expression. For this purpose, we focus on enhancing the perceptual capabilities of the flutist robot to process musical information coming from the aural and visual perceptual channels. In this paper, we introduce, as a first approach, a hands-free gesture-based control interface designed to modify musical parameters in real-time. In particular, we describe a set of virtual controllers, that a composer can manipulate through gestures of with a musical instrument. The gestures are identified by 2-D motion sensitive areas which graphically represent common control interfaces used in music production. The resulting information from the vision processing is then transformed into MIDI messages, which are subsequently played by the flute robot. In order to verify the effectiveness of the proposed gestural interface, we performed experiments to musically interact with musical partners. ¿From the experimental results we concluded that our method satisfies the technical and idiosyncratic requirements for being a suitable tool for musical performance.

Up to now, different kinds of musical performance robots (MPRs) have been developed. MPRs are designed to closely reproduce the required motor skills displayed by humans in order to play musical instruments. Our research, at Waseda University, has been focused on developing an anthropomorphic flutist robot. In this year, we have succeeded in developing the Waseda Flutist Robot No.4 Refined IV (WF-4RIV); which has improved the design of the mouth mechanism and reproduced the anatomy of the human lips better. In addition, the control system was improved to enable the robot to autonomously improve the quality of the sound during performance. For this purpose, we proposed to implement a new performance control system. From the experimental results, we confirm the improvements on the flute sound produced by the robot.

The focus of this special issue is to show how the main achievements on different technical topics relevant to the development of bioinspired and bioapplied mechatronic devices and robotic systems. The 19 articles in this special issue are summarized here.

We have developed a new three-dimensional talking robot Waseda Talker No. 6 (WT-6), which generates speech sounds by mechanically simulating articulatory motions as well as aero-acoustic phenomena in the vocal tract. WT-6 has 17-DOF vocal mechanism. It has three-dimensional lips, tongue, jaw and velum which form the 3D vocal tract structure. It also has an independent jaw opening/closing mechanism, which controls the relative tongue position in the vocal tract as well as the oral opening. The previous robot in the series had a 2D tongue and was not able to realize precise closure to produce human-like consonants such as /s/ or /r/. The new tongue, which can be controlled to form 3D shapes, is able to produce more realistic vocal tract shapes. The vocal cord model was also improved by adding a new pitch control mechanism that pushes from the side of the vocal cords. The pitch range is broader than that of the previous robot; it is sufficiently broad so as to be able to reproduce normal human speech. Preliminary experimental results showed improved synthesized speech quality for the vowels /a/, /u/ and /o/.

Many control methods have been studied on the assumption that the feet of biped robots contact the ground with four points. However, it is difficult for almost all of such biped robots to maintain four-point contact on uneven terrains because they have rigid and flat soles. In order to solve the problem, foot mechanisms should be studied. In 2003, we developed WS-1R (Waseda Shoes - No.1 Refined) which is able to maintain four-point contact. However, it is difficult to deal with the concave or convex ground because of the problems of the contact detection and sideways slip. So, WS-5 (Waseda Shoes - No.5) has been developed. To avoid the slip of the foot, a cam-slider locking system consisting of a solenoid and a cam is constructed and installed at the foot. Also, linear encoders are employed to measure the position of the foot sliders. Through walking experiments on uneven terrains, the effectiveness of WS-5 is confirmed.

Surgeons, during a medical intervention, perform different kinds of manual tasks with dexterity and precision. In order to assure the success of the intervention, medical students are trained several years using training models so that they can perform such tasks with accuracy to avoid any possible risk to patients. However, current training models are merely designed to imitate the surgical procedure without providing any further information about the how well the task was done. For that reason; in this paper, the development of a suture/ligature training system is proposed to imitate surgical procedures as well as provide quantitative information of the learning progress of trainees. As a first approach, a training system was designed to simulate the suture and ligature tasks. The proposed training system includes a skin dummy with an array of embedded photo interrupters to detect the movement of the skin dummy; without requiring any modification on the surgical instrument. In this paper, different task parameters were proposed to understand trainees' learning progress and different experiments were carried out to identify the evaluation parameters that may provide useful information about how well the task was performed. As a result from the experiments, the evaluation parameters for the suture and ligature were determined. Finally, an evaluation function was proposed and further experiments were proposed to verify its effectiveness. From the results of the experiments, we could effectively distinguish quantitatively the differences of skill levels between surgeons and unskilled persons as well as identifying the learning progress of trainees by plotting the learning curve

In this paper, the methodology for automatically generating an expressive performance on the anthropomorphic flutist robot is detailed. A feed-forward network trained with the error back-propagation algorithm was implemented to model the performance's expressiveness of a professional flutist. In particular, the note duration and vibrato were considered as performance rules (sources of variation) to enhance the robot's performance expressiveness. From the mechanical point of view, the vibrato and lung systems were re-designed to effectively control the proposed music performance rules. An experimental setup was proposed to verify the effectiveness of generating a new score with expressiveness from a model created based on the performance of a professional flutist. As a result, the flutist robot was able of automatically producing an expressive performance similar to the human one from a nominal score.

Previously, the realization of ascending and descending stairs and landing pattern modification control by WL-16RII were reported. However, it is difficult to use the landing pattern modification control when ascending stairs, because of the insufficient stroke of linear actuators. In this report, the design of a double stage linear actuator with a larger expansion and contraction ratio is described. The new linear actuators developed have been installed in WL-16RII, and several experiments were conducted. Through experiments involving walking with a wide step length and ascending a stair with landing pattern modification control, the effectiveness of the actuator developed is confirmed.

This paper describes how to compensate unknown external forces caused by a rider's motion of a biped walking vehicle. When external forces act on a robot's waist, the waist is accelerated so that a measured ZMP may be equal to a reference ZMP. To inhibit the divergence of the waist motion, the reference ZMP is varied inside a support polygon. However, if a large external force acts on a robot, the waist trajectory does not converge by only controlling a reference ZMP. So, ZMP trajectory is varied by changing a foot-landing point. Using the proposed control method, WL-16RIV (Waseda Leg-No. 16 Refined IV) achieved a stable human-carrying walking under unknown external forces which exert forward and sideways on the robot's waist. Through various walking experiments, the effectiveness of the proposed method was confirmed.

Experiments on animals has been playing very important part in psychology, medical science, genetics and brain science. Rodents are one of the most popular experimental subjects in these experiments. In psychology and brain science, behavior test and analysis on rodents, especially rats, has been performed to clarify mechanisms of mind or brain functions. "Open-field test" is one of the most popular research methods to investigate their behavior. In the "open-field test," rats are released into the "open-field," circle or square, flat arena surrounded by walls, and their behavior parameters such as position, moving distance, number of grooming and rearing are measured. With conventional experimental setups, these parameters has been measured and recorded by humans. Observing and recording are heavy task for experimenters, and also involves some human errors and subjectivity. Therefore, we developed an autonomous experimental setup which measures rats' position, number of grooming and rearing in the open-field. In addition, an active tracking camera which takes high resolution images of the rat in the open-field was developed. To prevent losing tracks of the rat, a prediction model of rat's movement is developed and integrated into the control of this camera.

Airway management is provided by emergency medical technicians or anesthetists in order to save unconscious patients who are unable to breathe. Even though it is a basic technique, many accidents may occur when the procedure is not provided followed. In order to avoid any risks to patients, emergency medical technicians are required to practice airway management using training devices such as mannequins; which are designed to accurately reproduce the human anatomy. However, such training devices do not provide any quantitative information about the learning progress of trainees (passive training). For that purpose, we have proposed the development of a airway management training system which is designed to embed array of sensors so that quantitative information of trainees' performance can be acquired. In this paper, we are presenting the Waseda-KyotoKagaku airway No. 1 (WKA-1). The WKA-1 consists of three different kinds of array of sensors which are embedded into a conventional mannequin. In order to embed the array of sensors, we have simplified the design of some of the simulated organs (upper airway, oral cavity, tongue and teeth) of the mannequin. A set of evaluation parameters were proposed based on the information collected through the sensors. A set of experiments were proposed to experimentally verify the effectiveness of the proposed evaluation parameters to quantitatively detect differences among different levels of skills (anesthetists and unskilled persons).

Authors have proposed as a long-term goal, since 2004, the development of a patient robot which could serve for both training purposes as well as an evaluation tool of medical procedures. As a first approach, we have developed last year a suture and ligature training system named Waseda Kyotokagaku Suture No. 1 (WKS-1), which is composed by a commercial skin dummy with arrays of embedded sensors designed to acquire quantitative data of the task. The WKS-1 was designed to reproduce realistically the task conditions as well as providing objective assessment of the task performance. In particular, the proposed evaluation function considered the following performance indexes: time, displacement and force levels. By performing experiments with medical doctors and unskilled persons, we confirmed the effectiveness of WKS-1 to provide objective assessments of the task performance. However, the functionalities of WKS-1 were too restricted as few automatic procedures were implemented for the acquisition and processing of the collected data. Therefore; in this paper, we are presenting the Waseda Kyotokagaku Suture No. 2 (WKS-2). The WKS-2 has been designed to provide more detailed information of the task performance as well as improving its portability, connectivity, and usability. In addition, thanks to the design improvements on the WKS-2, we have proposed additional evaluation parameters to measure the quality of the suture (after the task has been completed). For this purpose, we proposed a image processing algorithm to automatically measure the width of sutures, the distance among them and the wound area. Preliminary experiments were carried out to verify its effectiveness.

Our research on the anthropomorphic flutist robot has been focused on understanding the human motor control, enabling the communication between human and robots, proposing novel applications for humanoid robots and introducing novel ways of musical expression. In this video, we are presenting the musical skills of the Waseda Flutist Robot. In particular, we are presenting the WF-4RIV; which is able of performing musical performances requiring basic as well as extended technical skills. Thanks to the most recent mechanical improvements, the WF-4RIV is able of performing musical scores that are commonly part of the repertoire of intermediate level players. In this video, we are presenting the WF-4RIV performing the Flight of the Bumble Bee, Le Cygne and Trois Duos de Mendelssohn et Lachner.

As a result from our research, the Waseda Flutist Robot is able of playing the flute nearly similar to an intermediate level flutist. In order to enhance the expressiveness of its performance, we are focusing our research on improving the mechanical design of the simulated organs as well as implementing automated algorithms for the generation of expressive music performance. In a previous research, we have developed a human-like vocal cord to improve the production of vibrato. In this paper, we are presenting the newest version of the flutist robot; where the lips, oral cavity and tonguing mechanisms were improved. Such improvements were proposed to effectively control the attack time and double tonguing. The attack time is useful to produce clear sounds and the double tonguing is an important articulation that helps players to produce shaped notes and smooth transitions between notes. The lips mechanism is composed by 3-DOFs which enables the accurate control of the air stream parameters (width, thickness and angle). The lips of the robot were designed more human-like by using a thermoplastic rubber (septon). The oral cavity was designed similar to the human one also made by septon. Inside the oral cavity, an improved tonguing mechanism was designed (1-DOF) to reproduce better the double tonguing technique. A set of experiments were performed to analyze the improvements on the dynamical properties of the sound while playing the flute.

Minimally invasive surgery (MIS) has become very common in recent years, thanks to the many advantages it provides for patients. Since it is difficult for surgeons to learn and master this technique, several training methods and metrics have been proposed, both to improve the surgeon's abilities and also to assess his/her skills. This paper presents the use of the WB-1R (Waseda bioinstrumentation system no.1 refined), which was developed at Waseda University, Tokyo, to investigate and analyze a surgeon's movements and performance. Specifically, the system can measure the movements of the head, the arms, and the hands, as well as several physiological parameters. In this paper we present our experiment to evaluate a surgeon's ability to handle surgical instruments and his/her depth perception using a laparoscopic view. Our preliminary analysis of a subset of the acquired data (i.e. comfort of the subjects; the amount of time it took o complete each exercise; and respiration) clearly shows that the expert surgeon and the group of medical students perform very differently. Therefore, WB-1R (or, better, a newer version tailored specifically for use in the operating room) could provide important additional information to help assess the experience and performance of surgeons, thus leading to the development of a global performance index for surgeons during MIS. These analyses and modeling, moreover, are an important step towards the automatization and the robotic assistance of the surgical gesture.

The research on the anthropomorphic flutist robot, at Waseda University, has focused on clarifying the human motor control while playing the flute, proposing novel applications for humanoid robots and enabling the communication with humans at the emotional level. As a result of our research, the flutist robot is able of nearly reproducing the basic technical skills required to play the flute. Furthermore, some of the extended technical skills have been roughly simulated by the robot. However, in order to enhance the expressiveness of the robot's performance, still further improvements are required. In particular, in this paper, we focus our research on understanding better how to enhance the expressiveness of the flute performance by studying in more detail the vibrato, which is believe to be one of the most important ways of expressing feelings/ideas while performing the flute. For this reason, the newest version of the flutist robot, the Waseda Flutist Robot No.4 Refined III has been developed by focusing on improving the design of the lung and designing of a human-like vocal cord mechanism, which are believed to have a close relation in producing vibrato. The details of the new mechanism are given and experiments were conducted to understand the effect of the movement of diaphragm and glottis while producing vibrato.

The advances on robot technology, researchers are able designing human-like robots that are able of displaying more complicated motor skills as well as displaying some degree of intelligence. This robot could read a musical score and play a repertoire of 16 tunes on a keyboard instrument. In this talk, such research trends will be described based on the development of the Waseda Flutist Robot. This paper deals with 1) human-robot interaction: musical performance robots may aim in understanding how humans can communicate at the emotional level of perception. 2) human motor control: musical performance robots can be designed to nearly reproduce the anatomy/physiology of the human organs require for playing musical instruments. 3) art/entertainment: musical performance robots may contribute in finding new ways of musical expression that may have been hidden behind the rubric of "musical intuition". 4) education: musical performance robots may be used as education tools in order to transfer skills to unskilled persons.

We developed a sensor feedback mechanism for an anthropomorphic talking robot WT-5 (Waseda Talker No. 5). In human speech, sensory feedback is more important when we producing obstacle consonant sounds, such as /t/ and /d/, compared to the auditory feedback mechanism. We reproduce this mechanism by placing tactile sensors and a pressure sensor on the palate of a talking robot and reducing the error between the pressure of the human voice and the robot consonant production. In addition, we developed more efficient optimization methods than those of WT-4, using speech recognition and the pre-optimized memory of vowels. Using these mechanisms, we realized continuous mimic speaking that includes consonant sounds

Many researchers have been studied on acceleration control algorithms for biped robots to deal with uneven terrain. However, the control algorithms are difficult to be used for human-carrying biped walking robots because of modeling errors. In this paper, a landing pattern modification method is proposed which based on nonlinear compliance control. Theoretical compliance displacements calculated from a walking pattern are compared with the actual compliance displacements, while a robot's foot touches slightly uneven terrain. In result, the height of landing terrain is detected, and the preset walking pattern is modified. Using this method, a human-carrying biped robot would be able to walk stably on uneven terrain. This pattern modification method does not need any special sensors except force sensors. Through various walking experiments, the effectiveness of the method is confirmed

This paper describes one method to stop suddenly and safely avoid falling using only hardware and without a computer system. This method consists of attaching a braking function to leg actuators and the development of a fall avoidance mechanism, attached to the robot's foot. Using the human-carrying biped locomotor WL-16RII developed by Sugahara et al., the effectiveness of the method proposed in this paper was confirmed through an emergency stopping experiment during walking, while carrying a heavy load

Your face is one of the most important factors in communicating with people. At present, the TV-phone, which can transmit face information, is becoming a part of modern life. In order to transfer more realistic face information, we propose the face shape robot WD-1 (Waseda-Docomo face robot No.1), which can express various face shapes by morphing an average mask (made of SEPTON) through 19 facial control-points. In this study, an average face mask is made in order to express a wide range of shapes with few control points. The position, number and movement range of the control-points are optimized. In addition, we introduce 3-DOFs drive units and control each control-point on a plane, not at a point. In order to evaluate the performance of WD-1, we measure the shape error between the faces of three subjects and the WD-1 equivalents. We elucidate the weaknesses of the current WD-1 implementation: a paucity of control points on the face line and wrinkling of the mask due to excessive local stress

A new humanoid robot-WABIAN-2- that can be used as a human motion simulator is proposed in this paper. Its trunk is designed in order to permit rotation, and forward, backward, and sideway movement. Further, its arms are designed to support its complete weight when pushing a walk-assist machine. Moreover, it can lean on a walk-assist machine by forearm control using trunk motion. Basic walking experiments with WABIAN-2 are conducted with and without a walk-assist machine, thereby confirming its effectiveness

Many researchers have been studying on walking control methods for biped robots. However, the effectiveness of these control methods was not verified in outdoor environments such as pedestrian roads and gravel roads. In this paper, a landing pattern modification method adaptable to uneven terrain in a real environment is proposed which is based on a predictive attitude compensation control and a nonlinear compliance control. This method does not require any other sensors except force sensors. Also, a new biped foot system is described which can form larger support polygons on uneven terrain than conventional biped foot systems. Using the modification method and the foot system, WL-16RII (Waseda Leg-No.16 Refined II) achieved a stable walk on bumpy terrain with 20 mm height and 10 degrees inclination. Furthermore, a stable dynamic walk was realized on a paved road, when a human rode it. Through various walking experiments, the effectiveness of the method was confirmed

Personal robots, which are expected to become popular in the future, are required to be active in joint work and community life with humans. Such robots must have no bad physical or psychical effect on humans. The psychical effect of a robot on humans has been subjectively measured using questionnaires. However, it has not been objectively measured yet. Human emotion and the consciousness direction can be measured by physiological parameters and body motion, respectively. Therefore, the bioinstrumentation system WB-1 was developed in order to objectively measure the psychical effect of a robot on a human. It can measure physiological parameters such as respiration, heart rate, perspiration and pulse wave, and arm motion. Analyzing human stress in the interaction with a robot from electrocardiogram, the robot could generate a motion for decreasing the stress

A humanoid robot, WABIAN-2R, capable of human-like walk with stretched knees and heel-contact and toe-off motions is proposed in this paper. WABIAN-2R has two 1-DOF passive joints in its feet to enable it to bend its toes in steady walking. Further, it has two 6-DOF legs, a 2-DOF pelvis, a 2-DOF trunk, two 7-DOF arms with 3-DOF hands, and a 3-DOF neck. In addition, a new algorithm for generating walking patterns with stretched knees and heel-contact and toe-off motions based on the ZMP criterion is described. In this pattern generation, some parameters of the foot trajectories of a biped robot are optimized by using a genetic algorithm in order to generate a continuous and smooth leg motion. Software simulations and walking experiments are conducted, and the effectiveness of the pattern generation and mechanism of WABIAN-2R, which have the ability to realize more human-like walking styles in a humanoid robot, are confirmed

This paper describes a passive dynamic model of passenger for a biped walking vehicle. The walking pattern generation that enables stable walking even if passenger sits naturally is also described. The model consists of lower-limbs part assumed to be fixed to the robot, and the upper body assumed to be 1 particle with 2 DOF mounted on the seat via 2 springs and dampers. The parameters are identified through waist shaking experiments by using a force-torque sensor under the seat. The walking pattern generation method involves the proposed model being built onto a strict model of the robot, and through iteration computation, a stable walking pattern is generated. The effectiveness of the proposed method is confirmed through experiments

Presently, the simple head model (hereinafter referred to as phantom for practical training) with dentition models is used for dental therapy training. We suggested the patient robot for dental therapy training (hereinafter referred to as patient robot) as one of the practical applications of the humanoid robot technology, and we actually developed patient robots. One of them is the general model provided with 14 degrees of freedom (DOF) in addition to a tongue and lips that may interfere with treatment, allowing reflection of any change in simple expression. Also, active motions of the neck or hand allow various impediments so as to interfere with the actual potential treatment. The robot allowed trainees to do dental therapy training closer to the actual practice involving avoidance of these risks

This paper describes development of a new human-like talking robot WT-4 (Waseda Talker No. 4). WT-4 was developed to overcome the problems related to the lack of variation in the formant frequency of the sounds generated by the previous talking robot WT-3. These problems arose particularly on the first formant (F1) where frequencies of less than 500 [Hz] could not be reached. And the differences among WT-3’s vowels were not clear; which may have been caused by the sound source of the vocal cords and the lips. Therefore, the connection between the vocal cords and the vocal tract was improved, as well as the lips mechanism. As the result of these improvements, WT-4’s sounds were quite similar to a human’s, and WT-4 was able to reproduce suitable sounds using auditory feedback.

Biped walking is easily adaptable to rough terrain such as stairs and stony paths, but the walk speed and energy efficiency on the flat ground is not so effective compared with wheeled locomotion. In this paper, we propose a biped robot to be able to walk or wheel according to the ground conditions. For wheeled locomotion, WS-2 (Waseda Shoes -No. 2) is developed which is composed of a DC motor, a spherical caster and two rubber pads on each foot. WS-2 is attached to the feet of WL-16 (Waseda Leg -No. 16) that is the world's first biped-walking robot capable of carrying a human. Also, a path planning for wheeled locomotion is presented. Through hardware experiments, the effectiveness of this foot module is confirmed.

we would like to clarify the basic factors necessary for a symbiosis between creatures and robots through the interaction experiments between rats and robots. In our previous studies, we developed a robot involving two levers and conditioned the rat to push these levers to obtain food by experimenter’s teaching. In this paper, we try to condition the rats to push the levers on the robot to obtain food by the robot autonomously showing its functions without experimenter’s teaching. On animal psychology, “shaping” is used to condition animals to perform difficult or complex behavior that would rarely occur spontaneously. By importing the concept of “shaping,” we developed an operational pattern generation algorithm for the robot that enabled it to autonomously operate to show the rats its function. We then conducted an interaction experiment for evaluating this algorithm and confirmed the effectiveness of it. Thus, we proposed to import the concept of “shaping” into robot’s behavior generation to enable it to autonomously show creatures its functions.

This paper describes a walking control method on inclined planes for a biped locomotor. The walking control consists of a position control, virtual compliance control and posture control. Parameters of the compliance control are changed continuously in support and swing phases. The orientation of robot’s waist is kept level by posture control. Several walking experiments on inclined planes are conducted using WL-16R (Waseda Leg - No. 16 Refined). WL-16R has achieved stable walking on unknown inclined planes using the walking control method, and the effectiveness of the walking control is confirmed.

This paper describes the evaluation of three different walking patterns of a biped humanoid robot. Stretch-walking patterns with straight legs for a biped robot are compared with conventional walking patterns with bent legs in terms of energy consumption. This paper discusses walking pattern generation for various walks. To confirm the walking pattern evaluation, we have developed a biped robot, WABIAN-2/LL, whose leg mechanism differs from the conventional leg mechanism that has 3 DOF (degrees of freedom) in each ankle, 1 DOF in each knee, 3 DOF in each hip, and 2 DOF in the waist. Walking experiments are conducted with WABIAN-2/LL, and the results demonstrate that stretch walking patterns are effective in terms of energy consumption.

Personal robots, which are expected to become popular in the future, are required to be active in joint work and community life with humans. Therefore, we have been developing new mechanisms and functions for a humanoid robot that has the ability to express emotions and to communicate with humans in a human-like manner. In 2004, we introduced the "Behavior Model" and "Consciousness Model" to the robot mental model so that the robot generated various kinds of behavior and an object of the robot's behavior became clear. We implemented the mental model in the emotion expression humanoid robot WE-4RII (Waseda Eye No.4 Refined II). Also, we have been studying a system of multiple harmonic oscillators (neurons) interacting via chaotic force since 2002. Each harmonic oscillator is driven by chaotic force whose bifurcation parameter is modulated by the position of the harmonic oscillator. In this paper, we propose an associative memory model using mutually coupled chaotic neural networks for generating an optimum behavior to a stimulus. We implemented this model in the emotional expression humanoid robot WE-4RII (Waseda Eye No.4 Refined II).

We have developed a new talking robot, WT-5 (Waseda Talker No. 5), having novel vocal cords and lips based on human biological structures. The vocal cords are made from the thermoplastic rubber "Septon", available from Kuraray Co. Ltd, which has a similar elasticity to human tissue. The vocal cord model was constructed with a similar structure to the biological structure of the human vocal cords. The vocal cords vibrated like those of a human. The new lips were able to attain a large deformation in a similar manner to human lips, without the leakage of air. This allowed clear pronunciation of vowels. With these new mechanisms, the robot could reproduce human speech in a more biological manner and could produce voices closer to those of a human.

To date, many control methods have been studied, assuming that the soles of a biped walking robot contact the ground as four points. It is difficult for a biped robot with rigid and flat soles to maintain four-point contact on uneven terrain. It means that the biped robot can lose its balance. To solve this kind of problem, we should study not only stability control methods but also foot mechanisms. In this paper, a new foot system, WS-1 (Waseda shoes $no.1), is proposed to maintain four-point contact. This foot system consists of cam-type locking mechanism. WS-1 is attached to the feet of WL-16 (Waseda leg - no.16) that is the world's first biped-walking robot capable of carrying a human. Through hardware experiments, the effectiveness of the foot system is confirmed.

One of the earliest motivations for developing humanoid robots centered on creating robots that may coexist with humans in environments created for human beings. For several years, at Waseda University, the development of the anthropomorphic flutist player has been focused on improving the musical interaction between the human and the robot to clarify the human flute playing and to propose novel assisted music teaching tools. In this paper, a new architecture for autonomously transferring skills from robot to human using the flutist robot is introduced. Furthermore, the new version of the flutist robot, the WF-4R (Waseda Flutist No.4 Refined) is presented; where the arm system was added to assure the positioning accuracy of the flute and the development of a melody recognition system to enable the robot to interact with students at the same logical level of perception. An experimental setup has been performed in order to verify the effectiveness of both mechanical and perceptual systems. As a result, using the arms system, we have assured the repetitiveness of the flute positioning. Furthermore, the implemented music recognition system was able to recognize the melody of flutist players (an overall recognition rate of 90%); demonstrating that HMM (usually used for speech recognition) is also effective for flute melody identification.

This paper describes the means of tuning-up method of the walking parameters to go up and down stairs for a biped robot with leg mechanisms using Stewart platforms. It has been confirmed that the stroke range of use could be reduced by tuning up the waist yaw trajectory and preset ZMP trajectories for motion pattern generation. By using the developed method, a walking experiment involving movement up and down a stair with the rise of 250 mm and certain walking experiments ascending and descending stairs carrying a human were successfully completed. Through these experiments, the effectiveness of the proposed method was confirmed.

Since 1990, we have been developing anthropomorphic flutist robots, which are mechanically similar to human organs needed for playing the flute. The goal of this research is to clarify the flute playing mechanism from an engineering point of view and to enable the communication with humans at emotional level. The control of the air beam parameters for obtaining a good sound is very important. Such parameters are related mainly to the lips shape and its relative position respect to the flute embouchure hole. Then, the newest version of the anthropomorphic flutist robot WF-4 has been implemented by improving the design of each part of the robot (lips, lungs, neck, etc.). This new version has succeeded in the improvement of the flute sound quality and the sound conversion efficiency. We describe the mechanical features of the WF-4 and the experiments done for evaluating its musical performance.

We clarify the basic factors necessary for a symbiotic relationship between humans and robots. However, evaluating interaction between humans and robots is difficult due to a number of uncertain factors in human communication. Therefore, less sophisticated creatures, rats, were first selected, and we conducted interaction experiments between rats and robots. In our previous studies, we could not conduct these experiments for over 2 hours. We then developed a new experimental system to conduct the experiments without time restrictions. Using this system, we conducted two interaction experiments. In one experiment, the robot, meeting a rat's request, could live symbiotically with the rat. In the other experiment, the robot, behaving sequentially without having met the rat, could control the rat. This paper investigates the factors for a symbiotic relationship between a rat and a robot by comparing the two experiments.

The authors have been developing humanoid robots in order to develop new mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. We considered that human arms play an important role. And, in 2003, we developed the 9-DOFs emotion expression humanoid arm. Then, we developed the emotion expression humanoid robot WE-4R (Waseda Eye No.4 Refined) by integrating the new arms into the human-like head robot WE-4. Moreover, we introduced the new control algorithm for robot arm with redundant DOF into WE-4R. The new control algorithm was described by the junction of geometric constraint and robot emotion. We describe the mechanical design and the control algorithm of 9-DOFs emotion expression humanoid arm.

This paper describes the mechanisms and the speech production of a new advanced talking robot WT-3 (Waseda Talker-No.3) that improves on WT-2 (Waseda Talker-No.2) and is based on human acoustic theory for the reproduction of human speech. WT-3 consists of 1-DOF lungs and 3-DOF vocal cords and articulators (the 7-DOF tongue, 5-DOF lips, 1-DOF teeth, nasal cavity and 1-DOF soft palate), and can reproduce human-like articulatory motion; the total DOF is 18. The oral cavity is designed based on the MRI images of the human sagittal plane, although the cross section of the vocal tract is rectangular in shape except for the mouth. The width of the vocal tract is 30 [mm]. The average length of the vocal tract is approximately 175 [mm] and the same as that of a human's. Compared to the previous robots, WT-3 can produce vowels more clearly, and produce stops, fricatives and nasal sounds with the new flexible mechanisms that function as the human vocal tract area and the other mechanisms. WT-3 can mechanically reproduce human speech.

Almost all conventional biped humanoid robots have difficulties in realizing various walking motions such as knee stretch walking like a human because of an insufficiency of DOF. Therefore, we have developed a 16-DOF biped humanoid robot without a trunk: 3-DOF in each ankle, 1-DOF in each knee, 3-DOF in each hip and 2-DOF in the waist. Using the biped robot, basic experiments are conducted and the effectiveness of the leg mechanism is confirmed.

We developed a jaw movement training robot system implementing a 6-degree of freedom (DOF) parallel mechanism, and applied it to jaw opening and closing training, which is one of the therapies for temporomandibular joint disorders. As one application of this system, we developed an intermaxillary traction therapy system that provides non-physiological movements, whereby the patients' jaws receive traction to regenerate healthy temporomandibular joint tissue. This therapy is especially effective for patients with a symptom called "open bite", i.e. those who cannot completely close their jaws. Additionally, the previously developed mastication robot was applied to this robot system as a patient model, and the training movements of the training robot were evaluated.

The research of the anthropomorphic flutist robot at Waseda University, for more than ten years, has focused on reproducing as best as possible the human organs physiology involved on the human flute playing to clarify the mechanism from an engineering point of view. This research is based on the need to develop useful robots for practical uses in the human living environment. As a result of our research, the newest anthropomorphic flutist robot WF-4 (Waseda Flutist No. 4) with 24-DOF has been developed, which not only improved the expressiveness but reduced also the dimensions of all their mechanisms as closer to human size. The flutist robot is used as a tool to help a human professor to improve the sound quality of beginner flutist players. In such a case, the robot is not only used to reproduce human flute playing but to evaluate also pupil's performance and to provide useful verbal and graphical feedback in order to improve his/her performance. Therefore, while robot is transferring the basics of the skill to students; teacher is taking care about how to motivate them (student's psychology). An experimental setup was designed to compare the added value of using the flutist robot for teaching to beginner students against the conventional way of teaching. Students' performances have been analyzed through different methods. The results demonstrated that the performance of pupils were better when the robot was used.

This paper describes the mechanism of biped locomotor, WL-16 (Waseda Leg No. 16), its compliance control method and experiments carrying a human. This robot is developed based on WL-15's basic design using new gimbals' mechanisms with small backlash and new linear actuators dealing with a heavy payload and a wide movable range. Walking experiments carrying a human are successfully completed and the effectiveness of WL-16's mechanism and control method are confirmed.

The authors have been developing humanoid robots in order to develop new mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. We considered that human hands play an important role in communication because human hands have grasping, sensing and emotional expression abilities. Then, we developed the emotion expression humanoid robot WE-4RII (Waseda Eye No.4 Refined II) by integrating the new humanoid robot hands RCH-1 (RoboCasa Hand No.1) into the emotion expression humanoid robot WE-4R. Furthermore, we confirmed that RCH-1 and WE-4RII had effective emotional expression ability because the correct recognition rate of WE-4RII's emotional expressions was higher than the WE-4R's one. In this paper, we describe the mechanical features of WE-4RII.

This paper describes an autonomous control method of an anthropomorphic talking robot WT-4 (Waseda Talker No.4) to mimic continuous human speech sounds by auditory feedback. WT-4 consisted of 1-DOF lungs, 4-DOF vocal cords and articulators (the 7-DOF tongue, 5-DOF lips, 1-DOF teeth, nasal cavity and 1-DOF soft palate), and could reproduce human-like articulatory motion; the total DOF was 19. In this method, the trajectory of each robot parameter was controlled so that the acoustic parameters (pitch, sound power, formant frequencies that are resonant frequencies of the vocal tract and have the peak of the output spectrum, and the timing of the switch between voiced and voiceless sounds) generated from the robot were close to those of human speech sounds. The trajectory of each robot parameter was optimized by inputting the acoustic parameters. This method would help to clarify the human speech mechanism and to create a new speech production system.

This paper describes a method of motion pattern generation for biped humanoid robot to walk like humans or walk with various kind of motions. To realize biped walking avoiding singularity at stretching leg, pattern generation uses predetermined knee joint trajectories. Reduction of DOF by predetermination is complemented by waist motion. The effectiveness of generated dynamic walking patterns is confirmed by using a 16-DOF biped robot WABIAN-2/LL.

Recently, a few researchers have started to realize that in order for humanoid robots to move more naturally, it is necessary for them to incorporate a flexible spine in their robots. So far, nobody has come out with a solution which allows their spine robots to maintain balance in real-time. This paper presents a biologically inspired, hybrid CPG-ZMP controller for a single-legged, flexible spine belly dancing robot. Using only two control parameters, our robot can generate rhythmic and wave-like spine motions through the CPG component. By monitoring the torque at the robot's ankle, the ZMP component allows the robot to maintain balance in real-time. Unlike traditional ZMP-based controllers, no modeling of the robot's dynamics or explicit computations of the zero moment point are required. The resultant robot's motions emerge automatically in real-time through dynamic interactions between the robot, its neural network and the environment. Experimental results indicate that our controller has the potential to be applied to a new generation of flexible spine, biped walking humanoid robots.

This paper presents the design and development of a 3-axial artificial vestibular system to be integrated on robotic heads, in order to provide a sense of head position and motion. In accordance with the role of the vestibular system in humans, this artificial vestibular system is specifically devoted to regulate and stabilize gaze during head motion, by means of the vestibulo-ocular reflex (VOR) mechanism. Future applications explore the possibility of using the artificial vestibular system on human heads, as an indirect interface between humans and robots, for 'tele-control'.

The development of the anthropomorphic flutist robot was started since 1990. The aim of this research has been to reproduce the functionality of human organs to interact musically with humans and to clarify the mechanism involved in human flute playing from an engineering view point. The newest version of the flutist robot (WF-4) has improved considerably the functionality and human-like shape of the organs involved in the flute playing. Up to now, the flutist robot has been used to reproduce as best as possible the human performance, although it is desirable to be also useful to improve some of the required skills that beginner flutists must acquire; in this case, the sound quality. The robot could demonstrate several times the correct way of playing and provide useful feedback based on the analysis of the harmonic structure of the student's performance. Therefore, it becomes necessary to find performance indexes that enable the robot to classify and evaluate quantitatively learners' performances to provide feedback (verbal and/or visual) to correct their executions. In this paper, we briefly describe some of the improvements done on the newest version of the flutist robot and we present different ways how the robot can evaluate the human performance by an experimental setup.

This paper describes the development of the support torque reduction mechanism for a biped locomotor with leg mechanisms using Stewart platforms, designed for heavy payload and low power consumption during walking. The basic design of this mechanism was decided through preliminary experiments. Each leg of the robot is equipped with this mechanism consisting of 2 gas springs with different reaction forces, which are switched according to the swing/support phase. The experiment measuring motor current during walking with payload and the walking experiment with maximum payload confirmed the effectiveness of this mechanism.

In this paper a humanoid robot named as WABIAN-RIV (WAseda BIpedal humANoid Refined IV) is analyzed in terms of stiffness characteristics. This paper proposes basic models and a formulation in order to deduce the stiffness matrix as a function of the most important stiffness parameters of the WABIAN architecture. The proposed formulation is useful for numerical estimation of stiffness performances.

In this paper, we describe an anthropomorphic flutist robot that it's expected to have human-like organs from the mechanical hardware and control functions. We developed a "General Position" searching algorithm, which is based on the relative distance between the robot's mouth and the flute mouthpiece. It is possible for the robot, using the General Position, to blow a whole tone. Thereafter, we developed an autonomous searching algorithm for the lip part parameters after setting the General Position, and an algorithm for evaluating the blowing sound. The robot could stably play a flute using these algorithms.

The application of robots in contact with humans, in services or assistance, implies the realization of effective and acceptable human-robot interaction. In humans, vision plays a significant role in social interaction, like for example in the recognition of faces and expressions, as well as in gesture understanding. Visuo-motor coordination of eye and neck movements in humans presents high performances in terms of accuracy, speed, effectiveness. This is due to the mechanical, cinematic, and dynamic features of the head muscular-skeletal apparatus and to the peculiar processing of visual data, detected with a space variant resolution. The work presented in this paper aims at employing retina-like cameras in human-like robotic head, reproducing similar degrees of freedom, ranges of motion, speeds, and accelerations of human neck and eye movements, in order to improve visuo-motor coordination. The use of retina-like cameras allows a faster human-like processing of visual information, better suited for the control of head movements. On the other hand, retina-like cameras provide high resolution information only in a small area of the image and thus need to be dynamically focused on the points of interest. Experimental trials were focused on the capability of identifying and tracking human faces, as a first step of human-robot interaction. Preliminary experimental results show the feasibility of a smooth face tracking, by a closed control loop for the head movements, based on retina-like vision.

The authors have been developing human-like head robots in order to develop new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. Furthermore, the interaction between humans and robots is one of the essential factors for the Neuro-Robotics. We believed that the Mental Dynamics caused by the stimuli from the internal and external environment is important in expressing emotion. Therefore, we newly developed a human-like head robot WE-4 (Waseda Eye No.4) in 2002. The "Learning System", the "Mood Vector" and the "Second Order Equations of Emotion" were introduced to the mental model of the robot. Moreover, an internal clock was introduced as an autonomic nerve system to express the activation component of the Mood Vector. And, we realized the expression of mental transition caused by the stimuli from the internal and external environment of the robot. In this paper, we describe the new mental model of a human-like head robot WE-4.

METI has launched a national 5-year-project called Humanoid Robotics Project (HRP) since 1998 FY. Because humanoid robots have a human-like figure and can walk in a biped way and can take an action like a human being, we consider applying the humanoid robot platform in HRP to service fields of caring people such as the elderly, patients, etc. Taking the technical limitation of the current humanoid robot into account, we assume a situation where the robot serves such people. We regard the robot as users' avatar or another existence of users, and consider the class of users: a nurse, a patient, and a person in a remote site. This allows us to propose four types of user interfaces for the humanoid service robot system: an on/off-line user interface for a nurse who wants to control the robot as his avatar, a user interface for a patient who wants to control the robot as another existence, and a user interface for a person in a remote site who wishes to control the robot as his avatar. These user interfaces are described in this paper.

This paper describes a jaw movement training robot system implementing a 6 degrees of freedom (DOF) parallel mechanism, and its application for lateral movement raining. Temporomandibular joints (TMJ) problem is a disorder, whereby patients are not able to open their mouths nor move their jaws easily because of the problems with the mandibular joints, mastication muscles, and other organs concerning food chewing. Conventional therapy has been done with simple mouth opening apparatuses based on a doctor's technique through their own experiences, while this is still common. The authors have developed and improved a jaw movement training robot system, which provides not only jaw open and close training but also consists of a 6-DOF slave manipulator as a patient working manipulator and a 3-DOF master manipulator as a doctor commanding manipulator.

This paper describes a control and a structure of a battery driven bipedal robot, WL-15(Waseda Leg-15), which has a 6-DOF parallel mechanism. WL-15 has been designed as a multi-purpose locomotion of robotic systems. This robot is controlled by the QNX real-time operating system. Using Math Works' SIMULINK and OPAL-RT's RT-LAB executed on Windows NT and QNX target systems, control software and pattern generator are developed. A walking control capable of dealing with various dynamic walking is proposed and tested indoors and outdoors using the WL-15. Dynamic biped walking is realized with the maximum step length of 200 mm, the maximum walking speed of 0.8 s/step and the minimum speed of 1.92 s/step. Also, the WL-15 is confirmed to be able to turn 90 deg in two steps and carry a load of 18 kg.

The authors have been developing human-like head robots in order to develop new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. We believe that in the future, it will be necessary for personal robots to generate active behavior to interact bilaterally between human and robot. Therefore, we developed an emotion expression humanoid robot WE-4R (Waseda eye no.4 refined) in 2003. The need model consisting of the "appetite," the "need for security" and the "need for exploration" was introduced to the mental model for humanoid robots. We also defined the "need matrix" and introduced the "equations of need" to describe the robot needs. Robots with the need model can generate and express active behavior according to their need. This paper describes the need model that is implemented in the emotion expression humanoid robot WE-4R.

This paper describes the development of a new talking robot WT-2 that improved on WT-1R and has advanced vocal tract mechanisms for the reproduction of human vocal movement. WT-2 consists lungs, vocal cords, a vocal cavity and nasal cavity; the total DOF is 15. The length of the vocal tract is about 175 mm and is almost the same as that of an adult male. Compared to WT-1 or WT-1R developed previously, WT-2 could utter Japanese vowels more clearly, and produce stops, fricatives and nasal sounds by a new flexible tongue mechanism as well as decrease sound leaks from the tongue except those from the lips or nostrils.

This paper describes the modeling and analysis of an elastic tongue mechanism of a talking robot WT-2 and the development of an acoustic simulator for the construction of the computational model of human speech production. WT-2 consists of lungs, vocal cords and articulators. It is essential to accurately estimate and analyze the shapes of these organs to develop an acoustic simulator. However, it was difficult to estimate and analyze the mechanisms, because they were composed of an elastic rubber to make various shapes and to seal the air and sound. Therefore, we constructed a modeling method to simulate the shape of the elastic mechanisms. This method is applicable to all the elastic body. We developed an acoustic simulator using this modeling method in the process of constructing the speech production model.

This paper describes the knee stretch walking of the biped robot that has three degrees of freedom (DOF) in the ankle, one DOF in the knee and three DOF in the hip. To create the stable stretch walking pattern, a walking pattern generation method capable of specifying arbitrarily the knee joint angle is introduced. The motion of the waist avoids the singularity of the swing leg that can exist in single support phase. A compensatory motion algorithm to cancel the moments generated by the motion of the lower-limbs calculates the waist motion. Through stretch walking simulations, the effectiveness of the pattern generation method is confirmed.

This paper describes a control method for a stable biped walking on uneven terrain. The walking control consists of a position control and a compliance control. In order to realize dynamic walking on a human living environment, a biped locomotor is controlled by the position control based on a compensatory motion. Also, in this research, to reduce the magnitude of impact forces and to guarantee a stable landing on the ground, the position-based virtual compliance control is introduced. Several walking experiments on uneven terrain are conducted using WL-15 (Waseda Leg-15) and the effectiveness of the control method is confirmed.

This paper describes an online method generating walking patterns for biped humanoid robots having a trunk. Depending on the walking command, the motion patterns of the lower-limbs are created and connected to the prewalking patterns smoothly in online. For the stability of the biped robots, the trunk and the waist motion is generated by a walking stabilization control that is based on the ZMP trajectory and the motion of the lower-limbs. Experimental tests of versatile biped walking on a plane surface are conducted using an auditory interface, and the validity of the online pattern generation method is verified.

This paper describes the speech planning of the anthropomorphic talking robot WT-1R (Waseda Talker-No.1 Refined) for the production of consonant sounds. WT-1R has articulators (the tongue, lips, teeth, nasal cavity and soft palate) and vocal organs (the lungs and vocal cords), and can reproduce human vocal movement. Its total DOF (degrees of freedom) is 15. The vocal movement of WT-1R for vowels is steady. We produced Japanese vowels (/a/, /i/, /u/, /e/, /o/) using the first robot WT-1 in 2000. However, the vocal movement for consonant sounds is transient. We must control the 15-DOF talking robot coordinately in the space and time to reproduce the complicated phenomena of the consonant sounds. Therefore, because the Japanese voice generally consists of two phonemes of the first consonant sound and the last vowel, we proposed the speech planning of WT-1R by considering the phenomenon of the voice as three parts (steady consonant sound, transient consonant sound and vowel). WT-1R could produce Japanese vowels (/a/, /i/, /u/, /e/, /o/) and some consonant sounds (/s/, /h/, /m/, /p/ and /waseda/).

Conventional medical/dental systems have developed only doctor or patient models. However, two models are needed to quantify the dental/medical therapy; these are the patient model and the doctor model. The authors focus on the mouth opening and closing training done for the patients who have disorders on their jaw joints. The mastication robot as a patient model and the mouth opening-closing training robot as a doctor model are developed. The paper describes two robots that quantitatively evaluate the mouth opening and closing training. Force data using these two robots showed that robot training's force acting on the patient is smaller than the conventional training using a wooden device.

The authors have been developing human-like head robots in order to develop new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. We were able to simulate four sensations (the visual, auditory, cutaneous and olfactory sensations) of a human five senses by developing WE-3 (W_aseda E_ye No.3_) series since 1995. However, the robot system of WE-3 has become too complex and big from added improvements. Therefore, in 2002, we developed a new human-like head robot WE-4 (W_aseda E_ye No. 4_). We newly added a waist to WE-4, and realized emotional expression with not only the face, but also the upper-half part of the robot body. Also, WE-4 is smaller and lighter from revisions in mechanisms of the robot head In this paper we describe the mechanical features of the human-like head robot WE-4.

This paper describes the design of a battery driven bipedal robot, which uses 6-DOF parallel mechanisms for its each leg. We have designed this considering a bipedal robot as the leg module that is sufficient for practical use as a multi-purpose locomotor of the robot system. This robot is applicable to various fields, such as medical, welfare and entertainment. In the design of the robot, we have reduced the weight to the maximum extent, taking advantage of the features of the parallel mechanism where the mechanism rigidity is high. Using the developed bipedal locomotor, dynamic walking with the step time of 0.96 sec/step and the step length of 0.2 m/step was conducted, and the effectiveness of its mechanism was confirmed.

This paper describes the 6-degrees of freedom (6-DOF) jaw training robot that manipulates the patient's jaw to move sideway. Patients with jaw disorders who can not only control the opening/closing of their jaws, but also sideway movements are the target of this research. The authors developed a 6-DOF slave manipulator and 3-DOF master manipulator for these patients. The natural jaw's sideway motion was simulated by changing the center of rotation according to the rotational direction of the mandible. A real training for a jaw disorder patient using the robot was done, and the resulting distance to sideway was increased 9 to 15 mm in the right jaw joint and 7 to 12 mm in the left.

The authors have been developing new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. In this paper, they focus on the olfactory sensation and facial color that humans use to communicate with each other. Human's olfactory sensation recognizes over thousand different smells. The WE-3RIV (Waseda eye No.3 refined IV) developed can recognize the smell of alcohol, ammonia and cigarette smoke. The olfactory sensor consists of four semiconductor gas sensors. WE-3RIV is able to recognize certain smells within a few seconds of being presented with the smell stimuli by using the sensor output and the rate of changing of output. Further, we developed the facial color expression using red electro-luminescent sheets. By adding the facial color expression, the expressiveness of the robot and its facial expression are improved.

The authors deal with human-like head robots in order to develop new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. When humans communicate through auditory or visual sensations, they estimate their mental state through not only the information of each sensation but also their mental model. A robot's mental model consists of a 3D mental space having a pleasantness, and activation and a certainty axes. When the robot senses the stimulus, a mental vector moves in this mental space based on the equations of emotion. We also propose a robot personality which consists of sensing personality and expression personality. Further, we assign and load various sensing personalities.

Vocal movement is not only a movement of the vocal organs, it is also a movement that produces acoustic signals received by hearing as linguistic information through hydroacoustic phenomena along with the formation of the vocal way. The purpose of this research is to study the human vocal mechanism from the engineering point of view by simulating the vocal movement with a robot, and to create the dynamic model. The authors developed an anthropomorphic talking robot WT-1 (Waseda Talker-No.1) in 1999. It simulates human vocal movement, and has articulators (a 6-DOF tongue, 4-DOF lips, 1-DOF teeth, a nasal cavity and 1-DOF soft palate) and vocal organs (1-DOF lungs and 1-DOF vocal cords); the total DOF of the robot is 14. We experimented with it on Japanese vowels. However, the voice produced was not natural. In this paper we describe an improvement of the mechanisms for the realization of natural vowels and consonant sounds.

Describes a locomotion control for biped humanoid robots based on balance and and impedance control. The balance control is employed during a whole walking cycle, which can compensate for the moments generated by the biped walking. In the control, the compensatory motion of the trunk and waist is calculated from the trajectories of the lower-limbs, arms, head and ZMP. The parameters of the impedance control are adjusted in real-time according to the gait phase. The large damping coefficient of the impedance is applied to the landing leg to absorb the impact/contact force during the contact phase, while the large stiffness is given to increase the momentum reduced by the viscosity of the landing leg during the first half single support phase. By dynamic walking experiments using a human-like robot WABIAN-RIII, the validity of the proposed control methods is verified.

The authors have been developing human-like head robots in order to develop new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotions. We think that the personality of the robot is extremely important in attaining smooth and effective communication. We introduced a robot personality that consists of the sensing personality and the expression personality. The sensing personality determines how a stimulus works for a robot's mental state. A 3D mental space was defined in the robot. Seven emotions were mapped out in the 3D mental space. After the robot determines its emotion, it expresses its emotion by the expression personality. We expressed the expression personality using a matrix. Moreover, we assigned and loaded six robot personalities into the robot. The robot can express various personalities.

This research attempts to clarify the human vocal mechanism from engineering viewpoints by simulating the vocal movement with a robot, and to create a dynamic model. The authors developed an anthropomorphic talking robot, WT-1 (Waseda Talker-No.1) in 1999. It simulated the human vocal movement,. and had articulators and vocal organs. WT-1 could speak Japanese vowels (|a|, |i|, |u|, |e|, |o|). However, the vowels produced were not natural. Therefore, we develop a refined talking robot WT-1R that improves the realization of natural vowels and consonant sounds. WT-IR has articulators (the 6-DOF tongue, 4-DOF lips, 1-DOF teeth, a nasal cavity and a 1-DOF soft palate) and vocal organs (the 1-DOF lungs, 2-DOF vocal cords). The total DOF of the robot is 15. This paper describes the improved mechanisms of WT-IR and the realization of the fluctuation for the natural voice and the clearness of vowels.

Describes a skull robot as a patient simulator for mouth opening and closing training. The rehabilitation for patients who have problems on the jaw joint have been done primarily based on the doctor's qualitative experience and technique that is unknown to other people. The authors developed a skull robot WOJ-1R as a mechanical patient simulator This skull robot will be useful for the doctor to develop the strategy of training for the real human patient. Also, it will quantitatively clarify the effectiveness of the robots therapy compared with therapy by human. Experimental results of biting force comparison show that robot therapy force data acting on the skull robot was smaller than the conventional therapy by human.

This paper describes the remote training between Tokyo and Yamanashi with 6 degrees of freedom (DOF) parallel robot that is designed for the mouth-opening and -closing training. Remote training is useful for the patients who have difficulties to go to hospitals frequently. The authors have developed a master-slave training system using ISDN lines because ISDN is not difficult to come by in patients home. Mouth-opening and -closing training robot WY-5R (Waseda Yamanashi-5 Refined) realized the remote training via two ISDN lines with 128 kbps. As a result of remote therapy using WY-5R, two patients' mouth-opening and -forward distances increased.

This study is aimed at the realization of a continuous walking-pattern generated by combining some different patterns such as turning, forward, backward and side step patterns. A biped-walking robot is required to have the function of followability and stability to achieve continuous follow walking in a humans living environment. Unit patterns for a biped locomotion are continuously generated by a walking pattern generator, and the complete walking pattern for followability is determined by synthesizing the unit patterns. The compensatory motion of the trunk and waist that is calculated by a stabilization control method ensures the stability of combined walking patterns. To explore human-like walking, we have constructed a two-legged robot, WABIAN-RII (WAseda Bipedal humANoid robot-Revised II). Through hardware experiments, the continuous biped walking is realized.

The authors have been developing anthropomorphic head-eye robots, in order to elucidate the human vision system from an engineering point of view, and to develop a new head mechanism and function for a humanoid robot having the ability to communicate naturally with a human. We developed an anthropomorphic head-eye robot "WE-3R III" (Waseda Eye No.3 Refined III) having auditory sensation, cutaneous sensation and a facial expression mechanism with eyes, eyelids, eyebrows, lips, a jaw and a neck. It is said that the human cutaneous sensations include contact, pressure, cold, warmth and pain, so a tactile sensor and a temperature sensor were mounted on the robot. For the tactile sensor, we adopted a force sensing resistor. We think that the difference in touching methods such as 'push', 'stroke' and 'hit' have an effect on emotion, therefore we developed the method for recognizing those differences, and installed it in the robot. By improving and rebuilding the artificial psychological model of WE-3RII using a new concept-equations of emotion-in a 3D mental space, we realized expression of the mental state affected by various stimuli with WE-3R III.

This paper describes a 6 degrees freedom (DOF) parallel robot that is designed for the mouth opening and closing training. The rehabilitation for the patient who have problems on the jaw joint, mastication muscles, and other organs concerning the food chewing have been done primarily based on the doctor's technique. Conventional mouth opening apparatuses (such as wooden screws, bite blocks and clothespins-type apparatus) only increases mouth opening distance and do not have actuators, sensors, and/or control systems. Moreover, during therapy, the quantitative force data is unknown in spite of its importance for the standardization of mouth opening and closing training. Mouth opening and closing training robot WY-5 (Waseda Yamanashi No. 5) consists of mechanical, actuation, sensor and control systems. As a result of therapy using WY-5, the mouth opening distance increased.

In this paper, we introduce an attempt to realize communication between rats and rat-robots for the advancement of communication between humans and robots. By repeating certain interactions between rats and robots, we aim to clarify the effective factors in communication. The experimental system is equipped with a CCD camera above the experimental field. The positions of the rat and the rat-robot are calculated in real-time. We have developed the Rat-Robot WM-5 (W_aseda M_ouse-No.5). The main features of the robot consist of the similarity in figure and size, the remote control by an FM receiver, the ability to change direction on the spot by the use of a two-wheel mechanism, the shaking of the head, and the behavioral imitation of a rat's mounting. An interactive experiment between a rat and a rat-robot was carried out with the developed system. The rat's behaviors were compared in two cases. The rat-robot mounted the rat in one situation but didn't do it in another. We observed that the robot's action of mounting the rat makes the rat more interested in the robot for longer period of time, and thus the mounting of the robot by the rat occurred. As a result, the imitation of the rat's mounting seems likely to work well in the communication between rats and rat-robots.

This paper describes three emotions such as happiness, sadness and anger. The emotions are realized by the walking patterns of a biped personal robot that are defined by the parameterization of its whole body motion. The combined motion of the waist and trunk calculated by the compensatory control algorithm that has been proposed already is used to cancel the moments generated by the motions of the head, the lower-limbs and the upper-limbs. To experiment emotion expression, we have constructed a human-like personal robot WABIAB-RII (WAseda BIpedal humANoid robot-Revised II) that has forty-three mechanical degrees of freedom and four passive degrees of freedom. Simulation and experimental results of emotional walking are also presented.

We would like to give biped humanoid robots a following motion as one of the functions capable of supporting humans. Unfortunately, not much attention has been paid to research on human-following motions to date. In this paper, a follow-walking control method is described to realize such motions, which consists of a pattern synthesis part and a balance motion control part. First, we generate switchable unit patterns of a biped humanoid robot, based on human-robot interaction. Second, the unit patterns are synthesized according to the sense of the resultant contact forces. Finally, the compensatory motion of the trunk and waist is calculated by a cooperative motion control algorithm for the balance of the biped robot.

The authors have been developing anthropomorphic head robots in order to develop a new head mechanisms and functions for a humanoid robot having the ability to communicate naturally with a human by expressing human like emotion. We developed the anthropomorphic head-eye robot "WE-3RIV" (Waseda Eye No.3 Refined IV) which has four sensations and facially expresses emotions in 2000. We have recently added the olfactory sensation and the facial color expression function to its previous model, WE-3RIII, and we improved and rebuilt its artificial psychological model that consists of a 3D mental space having pleasantness, activation and certainty axes. When the robot senses the stimulus, a mental vector moves in the mental space based upon a set of differential equations in the mathematical formulation. We named it "equations of emotion. " We also introduced the robot personality, which consists of the sensing personality and the expression personality. WE-3RIV was realized to express the mental state affected by various stimuli based on the equations of emotion and the robot personality.

The vocal movement isn't only a movement of the vocal organs. It is also a movement that produces acoustic signals received by hearing as linguistic information through hydroacoustic phenomena along with the formation of the vocal way. The purpose of this research is to make clear human vocal mechanism from the view of engineering by reproducing the vocal movement using a robot, and to make the dynamic model. Therefore, the authors developed an anthropomorphic talking robot, WT-1 (Waseda Talker-No.1). It simulates human voice movement, and has articulators (the 4-DOF lips, 1-DOF teeth, 6-DOF tongue, nasal cavity and 1-DOF soft palate) and the vocal organs (the 1-DOF vocal cords, 1-DOF lungs); Total DOF of the robot is 14.

Describes remote training with a 6-degrees-of-freedom (DOF) parallel robot that is designed for training patients in mouth opening and closing. Rehabilitation for patients who have problems with their jaw joint, mastication muscles or other organs concerned with chewing food has been done primarily based on their doctor's qualitative experience and technique. Conventional mouth-opening apparatus (such as wooden screws, bite blocks and clothes-pin-type apparatus) only increases the mouth-opening distance and does not have any actuators, sensors and/or control systems. Moreover, during therapy, the quantitative data is unknown, inspite of its importance for the standardization of mouth-opening/closing training. The mouth-opening/closing training robot WY-5R (Wadaseda Yamanashi-5 Refined) realized the remote training via an ISDN line. As a result of remote therapy using WY-5R, the patient's mouth-opening distance increased.

The paper describes the balance control of biped locomotion systems. A biped humanoid robot is modeled and studied focusing on the realization of human-like walking. Firstly, the smooth motion of its lower limbs is characterized in terms of a set of walking variables. Secondly, to cancel moments produced by the motion of the lower limbs, the motion of its trunk and waist is derived by an iteration method. Finally, program control using a preset walking motion is applied to the biped robot. To confirm human-like walking, we have constructed a human-like biped robot called WABIAN-RII (WAseda BIped HumANoid robot-Revised II) that has a total of forty-three mechanical degrees of freedom (DOF). Experiments of a human-follow walking are conducted using the WABIAN-RII.

This research is aimed at the development of bipedal humanoid robots working in a human living space, with a focus on its physical construction and motion control method. At the first stage, we developed the bipedal humanoid robot WABIAN (Waseda bipedal humanoid), and proposed a control method for dynamic cooperative biped walking. In this paper, we present a follow-walking control method with a switching patterns technique for a bipedal humanoid robot to follow human motion by hand contact. By a combination of both algorithms, the robot is able to perform dynamic stepping and walking forward and backward in a continuous time while someone is pushing or pulling its hand. In this paper, the authors describe the control methods for the realization of physical interaction between a human and a bipedal humanoid robot.

The authors have been developing anthropomorphic head-eye robots, in order to elucidate the human vision system from an engineering point of view, and to develop a new head mechanism and function for a humanoid robot having the ability to communicate naturally with a human. We developed the anthropomorphic head-eye robot "WE-3RII" (Waseda Eye No.3 Refined II), with eyes, eyelids, eyebrows, lips, jaw and a neck. The robot has the ability to express an autonomous facial expression using three independent parameters of a psychological model. With the robot, the mechanism of changing eye movement from smooth pursuit eye movement to saccadic, and the control of scanning eye movement like that of a human's can be achieved. The robot is also able to express more human-like motion in pursuing a target by changing its eyeball control parameters, rather than that of WE-3R which we developed in 1996. Therefore, the authors have confirmed that WE-3RII has the ability to realize a pursuing motion in three dimensional space with its autonomous facial expression adapting to the target position and brightness like a human.

The authors have focused on the bipedal humanoid robot expected to play an active role in human living space, through studies on an anthropomorphic biped walking robot. As the first stage of developing a bipedal humanoid robot, the authors developed the human-size 35 active DOF bipedal humanoid robot "WABIAN" and the human-size 41 active DOF bipedal humanoid robot "WABIAN-R". The authors also proposed a basic control method of whole body cooperative dynamic biped walking that uses trunk or trunk-waist cooperative motion to compensate for three-axis (pitch, roll and yaw-axis) moment generated not only by the motion of the lower-limbs planned arbitrarily but by the time trajectory of the hands planned arbitrarily. Using these systems and the control method, normal biped walking (forward and backward), dynamic dance, waving arms and hip, dynamic carrying of a load using its arms, and trunk-waist cooperative dynamic walking are achieved.

Presents the human safety mechanisms of a human friendly robot (HFR) capable of coexisting with human beings. In order to realize human safety, the HFR is required to be composed of an elastic material-covered manipulator and a passive viscoelastic trunk mounted on a passively movable base like a human's structure. During an expected or unexpected collision/contact between the HFR and its environment, the produced collision/contact forces are extremely attenuated by the combination motion of the passive viscoelastic trunk and passively movable base. The collision-tolerant control algorithm has been developed for the end-effector of the HFR to maintain its desired task during the expected or unexpected collision. Results of collision experiments show that the compliant trunk and movable base are effective mechanisms of suppressing collision forces, and the control algorithm is an effective method of positioning the end-effector.

Describes the development of a mouth-opening and -closing training robot WY-3 (Waseda Yamanashi-3) that has been designed and developed by combining oral-maxillofacial surgery and robotics. Mouth-opening training is useful for the rehabilitation of patients who have problems opening and closing their mouths. Conventional mouth-opening apparatus (such as wooden screws, bite blocks and clothespins type apparatus) only increase mouth-opening distance and do not have actuators, sensors, and/or control systems. Moreover, during therapy the quantitative force data is unknown in spite of its importance for the standardization of mouth-opening and -closing training. The mouth-opening and -closing training robot WY-3 consists of mechanical, actuation, sensor, and control systems. As a result of therapy using WY-3, the mouth-opening distance increased from 36 to 41 mm.

We have proposed the collision-tolerant mobile manipulator equipped with a passive trunk (i.e., supporting part). In collision experiments with unknown environments, results show that this mechanism is suitable for the suppression of contact forces which is an important issue for human-robot collaborations. The trunk with mechanical elements such as springs and dampers is passively deformed to deal with physical contacts, while the mobile platform moves around on the horizontal plane in response to friction between the platform and the ground. The end-effector of the manipulator, however, is difficult to track a desired task due to the deformation of the compliant trunk and the mobility of the platform. In order to solve the problem, the desired joint configurations of the manipulator are directly calculated according to the movement of the trunk and the platform, and a feedback control scheme is employed.

In this study the authors have been developing anthropomorphic head-eye robots, in order to elucidate the human vision system from an engineering point of view, and to develop a new human-friendly communication system. We developed an anthropomorphic head-eye robot "WE-3R" (Waseda Eye No.3 Refined) as a human-friendly head-eye subsystem of a humanoid robot "Hadaly-2". WE-3R has eyelids as hardware, while the functions of retina (adaptation) and iris (adjustment of the pupil diameter) are realized as software so WE-3R can adjust to brightness. The system can pursue objects in 3 dimensional space with adjusting to the brightness in a human-like manner that can be considered important for smooth and natural human-robot interaction.

This paper describes the quantification of masticatory efficiency by using a mastication robot that was developed as a mechanical simulator of human masticatory jaw motion on the basis of dental robotics. The masticatory efficiency is evaluated on the basis of human mastication and the quantification of masticatory efficiency is studied experimentally. In this paper, the authors use the sifting test to quantify efficiency. The results of chewing experiments with robot by comparing the differences in chewing motion between clenching and grinding showed that the masticatory efficiency of the latter was higher than that of the former.

The authors introduce a life-size biped walking robot having antagonistic driven joints using a nonlinear spring mechanism and a dynamic biped walking control method using these joints. In the current research concerning a biped walking robot, there is no developed example of a life-size biped walking robot with antagonistically driven joints by which the human musculo-skeletal system is imitated in lower limbs. Humans are considered to walk efficiently using the inertial energy and the potential energy of the lower limbs effectively, walk smoothly with less impact force when a foot lands and cope flexibly with the outside environment. The human joint is driven by two or more muscle groups. Humans can vary the joint stiffness, using nonlinear spring characteristics possessed by the muscles themselves. These functions are indispensable for a humanoid. However, the biped walking robots developed previously have been unable to walk in this way. Therefore, the authors developed a biped walking robot having antagonistic driven joints, and proposed a walking control method for dynamic biped walking that uses antagonistic driven joints to vary joint stiffness. The authors performed walking experiments using the biped walking robot and the control method. As a result, dynamic biped walking varying the joint stiffness using antagonistic driven joints was realized.

In this paper, we introduce a trial to realize interaction between creatures and robots. As the first step, rats were selected as an experimental target as a simplified form of interaction between human and humanoid robots. A rat robot was developed. Infrared transmitter, similar outlook of rat's figure and size, front-wheel steering and rear-wheel driving mechanism were equipped to the robot as the main features of the robot. An experiment system was developed to enable interaction between the rat robot and rats. The experiment system is equipped with a color CCD camera which captures and processes images of the rat and the rat robot in real-time. Behavioral experiments were performed with the system. As a result, it was confirmed that behaviors of the rat robot influence the rat's behaviors.

The authors proposed the construction of a bipedal humanoid robot that has a head system with visual sensors, two hand-arm systems, 3-DOF trunk and antagonistic driven joints using the nonlinear spring mechanism, on the basis of WL-13. And we really designed and built it. In addition, as the first step to realize the dynamic cooperative motion of limbs and 3-DOF trunk, the authors developed the control algorithm and the simulation program that generates the trajectory of 3-DOF trunk for stable biped walking pattern even if the trajectories of upper and lower limbs are arbitrarily set for locomotion and manipulation respectively. Using this preset walking pattern with variable muscle tension references correspond to swing phase and stance phase, the authors performed walking experiment of dynamic walking forward and backward dynamic dance with 3-DOF trunk motion and carrying, on a flat level surface (1.28 s/step with a 0.15 m step length). As a result, the efficiency of our walking control algorithm and robot system was proved. In this paper, the mechanism of WABIAN and its control method are introduced.

The authors are engaged in studies of biped walking robots from the following two viewpoints. One is a viewpoint as a human science. The other is a viewpoint towards the development of humanoid robots. In the current research concerning a biped walking robot, there is no developed example of a life-size biped walking robot with the antagonistically driven joints by which the human musculo-skeletal system is imitated in lower limbs. Humans are considered to exhibit walking behavior, both efficient and capable of flexibly coping with contact with the outside environment. However, developed biped walking robots can not realize the human walking. The human joint is driven by two or more antagonistic muscle groups. Humans can vary the joint stiffness, using nonlinear spring characteristics possessed by the muscle themselves. The function is an indispensable function for a humanoid. Therefore, the authors designed and built an anthropomorphic biped walking robot having antagonistic driven joints. In this paper, the authors introduce the design method of the robot. The authors performed walking experiments with the robot. As a result, quasi-dynamic biped walking using antagonist driven joint was realized. The walking speed was 7.68 s/step with a 0.1 m step length.

In this study the authors are developing anthropomorphic head-eye robots, in order to elucidate the human vision system from an engineering point of view, and to develop a new communication system with humans. We have developed an anthropomorphic head-eye robot with 2-DOF eyes and a 4-DOF head rotation mechanism, WE-3 (Waseda Eye No.3), that comprises a subsystem of an anthropomorphic robot 'Hadaly-2' which we are developing in 'Humanoid Project' at Waseda University. Since the camera drive mechanism need light-weight and immune to backlashes, the eyeball part uses a tendon-driven gimbal mechanism. The neck part except yaw axis is also driven by tendon-driven mechanism. In this experiment, the target is a electric light bulb. The head-eye robot, WE-3 has realized coordinated head-eye motion with VOR (vestibulo-ocular reflex) of human, and pursuing motion in the depth direction using the angle of convergence, with the same speed as humans.

The authors develop an anthropomorphic head-eye robot, in order to elucidate the human vision system from an engineering point of view and to develop a new communication system with humans. The robot developed, Waseda Eye 3 (WE-3), has 2-DOF eyes and a 4-DOF head rotation mechanism and comprises of the anthropomorphic robot 'Hadaly-2', developed at the Waseda University, as a subsystem. Since the camera drive mechanism needs light-weight and immune to backlashes, the eyeball part uses a tendon-driven gimbal mechanism. The neck part, except the yaw axis, is also driven by tendon-driven mechanism. In this experiment, the target used is a electric light bulb. The WE-3 head-eye robot realized a coordinated head-eye motion similar to the vestiburo-ocular reflex of human, and pursued motion in the depth direction using the angle of convergence, with the same speed as humans.

This paper describes the mathematical and mechanical models that simulate the nonlinearity of human's masticatory muscle. In addition, the experimental results of a real food chewing experiment by a mastication robot is described. When the lower jaw rapidly closes during the chewing motion, it may come in hard contact with the upper jaw if the food is a crushable one. To clarify the mechanism of this reflective jaw motion, the authors focused on the nonlinearity of human's masticatory muscle. The authors propose a feasible mathematical model of the muscle and its nonlinearity. A nonlinear viscoelastic mechanism is designed based on the mathematical model. From the result of chewing experiment, the authors confirmed the effectiveness of the proposed mechanism for the control of the robot jaw.

The authors are engaged in studies of biped walking robots from the following two viewpoints. One is a viewpoint as a human science. The other is a viewpoint towards the development of humanoid robots. In the current research concerning a biped walking robot, there is no developed example of a life-size biped walking robot with the antagonistically driven joints by which the human musculo-skeletal system is imitated in lower limbs. Humans are considered to exhibit walking behavior, both efficient and capable of flexibly coping with contact with the outside environment. However, developed biped walking robots can not realize the human walking. Humans can vary the joint stiffness, using nonlinear spring characteristics possessed by the muscle themselves. The function is an indispensable function for a bipedal humanoid. Therefore, the authors designed and built a biped walking robot and a bipedal humanoid having antagonistic driven joints. In this paper, the authors introduce the design method of the biped walking robot. The authors performed walking experiments with the biped walking robot and the bipedal humanoid As a result, quasi-dynamic biped walking, dynamic walking, dynamic dancing with dance music and carry with dynamic walking using antagonist driven joint were realized.

In this paper, the authors introduce an anthropomorphic dynamic biped walking robot adapting to the humans' living floor. The robot has two systems: 1) a special foot system to obtain the position relative to a landing surface and the gradient of the surface during its dynamic walking; 2) an adaptive walking control system to adapt to the path surfaces with unknown shapes by utilising the information of landing surface, obtained by the foot system. Two units of the foot system WAF-3 have been developed: a biped walking robot WL-12RVII that has the foot system and the adaptive walking control system installed inside it. A walking experiment with the WL-12RVII was performed. As a result, dynamic biped walking adapting to humans' living floor with unknown shape was realised. The maximum walking speed was 1.28 s/step with a 0.3 m step length, and the adaptable deviation range was from -16 to 16 mm/step in the vertical direction, and from -3 to +3/spl deg/ in the tilt angle.

The purpose of this study is to clarify the mechanism on human's flute playing from engineering view point. To accomplish this purpose, the authors developed an anthropomorphic flautist robot WF-3RII (Waseda Flutist No.3 Refined II), which reproduces the functions of human organs: a respiratory system, a playing attitude control mechanism, fingers, a mouth, a throat, a tongue, etc. WF-3RII realized the musical performance, "Mozart W.A., Flute Quartets KV 298" with MIDI tone generator module accompaniment. This work is a part of the "Humanoid Project" being done in Waseda University.

As the first stage of dynamic biped walking adapting to an unknown uneven surface using an anthropomorphic biped walking robot, this paper introduces a special foot mechanism with shock-absorbing material that stabilizes dynamic biped walking and acquires position information on the landing surface. The new foot has three functions: (1) a function to obtain information on the position relative to a landing surface; (2) a function to absorb the shock of the foot landing; and (3) a function to stabilize changes in the support leg. Two units of the foot mechanism were produced, a biped walking robot WL-12RVI that had the foot mechanism installed inside it was developed and a walking experiment with WL-12RVI was performed. As a result, decreased vibration around the pitch axis, decreased torque demands on ankle actuators on the pitch axis, increased dynamic biped walking success probability, and acquired landing surface information were achieved.

The authors have started to study on the development of a hydraulically powered quadruped walking robot having a trunk which stabilizes its walking by generating compensation moment to the ground for higher mobility on a flat floor. This paper describes a motion control method of the trunk for moment compensation and results of dynamic simulation for the walking.

Describes mathematical models that simulate the nonlinearity of the human muscle, and the results of a real food chewing experiment by a mastication robot. When the lower jaw rapidly closes, it may come in hard contact with the upper jaw if the food is a crushable one. To clarify the mechanism of rapid jaw motion, the authors focused on the nonlinearity of the human muscle that is known in the field of the physiology or biomechanisms. The authors propose a feasible mathematical model for the muscle and its nonlinearity. A nonlinear spring mechanism is then designed based on the mathematical model. As a result of chewing experiment, the authors confirmed control of the rapid closing motion of the robot jaw using the nonlinear spring mechanism. This work was done as part of the "Humanoid Project" at HUREL (Humanoid Research Laboratory).

A mastication robot is a jaw motion simulator that has similar structure and function to the human masticatory system. This paper describes an optimal reduction of the jaw joint force focusing on the fan shape of the musculus temporalis (M.temporalis) spreading around the side of skull. The shape of M.temporalis is simplified as two independent lines, and the jaw joint force is computed by using linear programming. Furthermore the actuators corresponding to the anterior and posterior parts of M.temporalis are assigned separately. The 28% reduction of jaw joint force was confirmed experimentally by using robot.>

In this paper, as the first stage of biped walking adapting to an uneven surface using an anthropomorphic biped walking robot, the authors introduce a biped walking control method for adapting to a surface that is called a horizontally composed (HC) plane whose step height is unknown, and a special foot mechanism which is capable of shock absorbtion. The authors developed an anthropomorphic biped walking robot with a foot mechanism and performed walking experiments with the robot using the control method. As a result, adaptive dynamic biped walking over a step of unknown height was realized. The maximum walking speed was 0.96 sec per step with a 0.3 m step length, and the greatest step height was 12 mm. The authors believe that the adaptability is integral to an anthropomorphic robot that will support human living in the near future. The authors call the robot Humanoid.>

The authors propose learning control methods for compensative trunk motion for a biped walking robot that has a trunk, based on the ZMP (zero moment point) stability criterion, for the cases of the ZMP being inside the stable region and outside the stable region, respectively. They have developed a biped walking robot with a ZMP measurement system and a support device. The results of computer simulation and learning control experiments confirm the convergence of the learning methods and the change of the convergence rate with the change of the weight coefficient. The learning control experiments for the case of the ZMP being outside the stable region show that even though the walking state of the robot itself changes, with the support of a human and by its learning with the ZMP and the support force, stable walking even without the support of a human ultimately is realized.

This paper describes a mechanism for a mastication robot using a human skull model. Since 1986 the authors have been developing the WJ (Waseda Jaw) series of mastication robots by using a dental study model, a duralumin mandibular, DC motors, wires, etc. From 1986 to 1991 the authors developed mastication robots with a mechanical mandibular model, and experimented with these robots. However, in order to analyze the human masticatory system, the authors needed a model closer to the human. The characteristics of the new mastication robot mechanism developed in 1992 are, that this robot has a structure similar to the human by using a skull model and, that the argument of the temporalis muscle force vector is variable by using two actuators. On the basis of this robot, the authors will be able to clarify and construct a quantitative and dynamic masticatory model for human mastication because it has human-like structures.

The authors have been using the ZMP (zero moment point) as a criterion to distinguish the stability of walking for a biped walking robot which has a trunk. The authors introduce a control method of dynamic biped walking for a biped walking robot to compensate for the three-axis (pitch, roll and yaw-axis) moment on an arbitrary planned ZMP by trunk motion. The authors developed a biped walking robot and performed a walking experiment with the robot using the control method. The result was a fast dynamic biped walking at the walking speed of 0.54 s/step with a 0.3 m step on a flat floor. This walking speed is about 50% faster than that with the robot which compensates for only the two-axis (pitch and roll-axis) moment by trunk motion.

The authors have been using the ZMP (Zero Mo- ment Point) as a criterion to distinguish the stability of walk- ing for a biped walking robot that has a trunk. In this paper, the authors propose a learning control algorithm of the com- pensative trunk motion that makes the actual ZMP get closer to the desired ZMP. The convergency of the algorithm is con- firmed by computer simulation and learning experiments with the biped robot. The change of the convergence rate with the change of the weight coefficient multiplied to the errors be- tween the measured ZMP and the desired ZMP is confirmed by the simulation and the experiments. And also the reasons are discussed.

Concerns the use of the zero moment point (ZMP) as a criterion in order to distinguish the stability of walking for a biped walking robot. If the ZMP during walking can be measured, it is possible for a biped walking robot to realize stabler walking by a control method that makes use of the measured ZMP. A method of measuring the ZMP throughout the whole walking phase is proposed, and a newly developed biped walking robot that has a ZMP measurement system using two universal force-moment sensors is explained. The accuracy of the ZMP measurement system is experimentally confirmed, and the ZMP throughout the whole walking phase is measured.>