We present a nonrigid shape matching technique for establishing correspondences of incomplete 3D surfaces that exhibit intrinsic reflectional symmetry. The key for solving the symmetry ambiguity problem is to use a point-wise local mesh descriptor that has orientation and is thus sensitive to local reflectional symmetry, e.g. discriminating the left hand and the right hand. We devise a way to compute the descriptor orientation by taking the gradients of a scalar field called the average diffusion distance (ADD). Because ADD is smoothly defined on a surface, invariant under isometry/scale and robust to topological errors, the robustness of the descriptor to non-rigid deformations is improved. In addition, we propose a graph matching algorithm called iterative spectral relaxation which combines spectral embedding and spectral graph matching. This formulation allows us to define pairwise constraints in a scale-invariant manner from k-nearest neighbor local pairs such that non-isometric deformations can be robustly handled. Experimental results show that our method can match challenging surfaces with global intrinsic symmetry, data incompleteness and non-isometric deformations.

A controller design to suppress vertical vibration of a position controlled biped walking robot is presented. The system model of structural vibration is estimated from a measurement of frequency response. By using the model, an optimal feedback controller with full state observer is designed. With a consideration of leg support phase, the vibration controller is combined into our walking controller. The effectiveness of our controller is experimentally demonstrated.

This paper presents a method for generating a turning motion in a humanoid robot by allowing the feet of the robot to slip on the ground. As humans, we exploit the fact that our feet can slip on the ground, and allowing humanoid robots to realize this same motion is a worthwhile study. In this paper, we propose the hypothesis that a turning motion is caused by the effect of minimizing the power generated by floor friction. A model of rotation from this friction is then described based on our hypothesis. The proposed model suggests that only the trajectory and shape of the robot's feet determine the amount of rotation from a slip, and that the friction coefficient between the floor and the soles of the robot, as well as the velocity of the feet, do not affect the resultant angle. Verification is conducted through an experiment with a humanoid robot known as HRP-2. Next, to obtain the foot motion necessary to realize the desired rotational angle, the inverse problem is solved by confining the trajectory of the center of the foot to an arc shape. This solution is verified through an experiment with another humanoid robot, HRP-4C.

In this paper, we describe three singing information processing systems, VocaListener, VocaListener2, and VocaWatcher, that imitate singing expressions of the voice and face of a human singer. VocaListener can synthesize natural singing voices by analyzing and imitating the pitch and dynamics of the human singing. VocaListener2 imitates temporal timbre changes in addition to the pitch and dynamics. In synchronization with the synthesized singing voices, VocaWatcher can generate realistic facial motions of a humanoid robot, the HRP-4C, by analyzing and imitating facial motions of a human singing that are recorded by a single video camera. These systems that focus on “imitation” are not only promising for representing human-like naturalness, but also useful for providing intuitive control means.

We present the realization of quick turning motion of a humanoid robot on its toes via slipping between its feet and the floor. A rotation model is described on the basis of our hypothesis that turning via slip occurs as a result of minimizing the power caused by floor friction. Using the model, the trajectory of the center of the foot can be generated to realize the desired rotational angle. Toe joints are used to realize quicker turning motion, while avoiding excessive motor load due to frictional torque. Quick slip-turn motion with toe support is successfully demonstrated using a humanoid robot HRP-4C.

This paper presents a reaching motion planning and execution framework tailored for exploration missions by human-operated humanoid robots in hazardous environments such as nuclear plants. This framework offers low-level but practical autonomy that allows the robot to plan and execute simple tasks, such as reaching a target object, within a reasonable amount of time. The human operator benefits from the efficiency of the framework to maneuver the robot without waiting for the planning results for minutes. The efficiency improvement is achieved in the following two phases. In the first phase, a reaching motion is planned quickly through approximation of mass distribution and kinematic structure to apply analytical solutions of inverse kinematics. Supposing that the robot is working in environments not completely known, the proposed planner can use measured voxel maps. In the second phase, the planned path is executed while compensating the approximation error in real time without violating other constraints. We confirm through simulations that a reaching motion for the HRP-2 humanoid with 30 DOFs in a constrained environment with pipes is planned in around one second. The simulation results also validate the efficiency of execution with real-time error compensation.

This paper deals with the practical problem as to how a humanoid robot opens a door in an office environment. Among the several tasks for the door opening, we focus on the recognition of a door and grasping its knob and propose a systematic touch scheme that combines the visual and touch data to grasp a knob safely and robustly. The visual recognition of a door and its knob is done by feature matching by a feature classifier and a segmentation method with minor assumptions about a knob, respectively. The position of a knob from the visual recognition is refined by the proposed touch scheme where a robot touches a knob several times with a hand equipped with a force-torque sensor. We realize that in the on-line experiment, a robot recognizes a door and its knob, and grasps the knob and partially opens the door.

This paper deals with the practical problem of how a humanoid robot recognizes a door and its knob in an office environment. This is the initial work where a humanoid robot recognizes, approaches, and opens a door. We propose an integrated solution for visual recognition of a door and its knob with minor constraints. In our approach, the door recognition is transformed into the classification problem of feature points, which can be done quickly enough to conduct it on-line. The knob is extracted by a segmentation method and a few thresholds: blob size, blob ratio, and the distance from the floor. We show in the experiment that our humanoid robot can recognize a door and its knob reliably and quickly.

In this paper, we describe VocaWatcher, a novel robot motion generator that enables a humanoid robot to sing with realistic facial expressions and naturally synthesized singing voices. This robot singer is an important and attractive humanoid robot application for the entertainment scene; moreover, it promotes state-of-the-art integration of robot engineering, music processing, and image processing. To overcome the difficulties of generating natural facial expressions that are precisely synchronized with singing voices, VocaWatcher imitates a human singer by analyzing a video clip of a human singing, recorded by a single video camera. VocaWatcher can control mouth, eye, and neck motions by imitating the corresponding human movements, which are estimated without using any markers in the video. It can also synthesize singing voices by imitating the pitch and dynamics of the human singing in the same video.

Hardware improvement of cybernetic human HRP-4C for entertainment is presented in this paper. We coined the word ¿Cybernetic Human¿ to explain a humanoid robot with a realistic head and a realistic figure of a human being. HRP-4C stands for Humanoid Robotics Platform-4 (Cybernetic human). Its joints and dimensions conform to average values of young Japanese females and HRP-4C looks very human-like. We have made HRP-4C present in several events to search for a possibility of use in the entertainment industry. Based on feedback from our experience, we improved its hardware. The new hand, the new foot with active toe joint, and the new eye with camera are introduced.

This paper presents the development of humanoid robotics platform - 4 (or HRP-4 for short). The high-density implementation used for HRP-4C, the cybernetic human developed by AIST, is also applied to HRP-4. HRP-4 has a total of 34 degrees of freedom, including 7 degrees of freedom for each arm to facilitate object handling and has a slim, lightweight body with a height of 151 [cm] and weight 39 [kg]. The software platform OpenRTM-aist and a Linux kernel with the RT-Preempt patch are used in the HRP-4 software system. Design concepts and mechanisms are presented with its basic specification in this paper.

In order to execute multiple tasks in offices and houses, robots require a large amount of information. If each item that is part of the ambience is endowed with some intelligence, robots can simply change the state of the item as requested by the item itself. We refer to such an ambience as “intelligent ambience (IA).” This paper describes a constitution method for designing an IA. We constructed two IA models - one comprised a drawer and a mobile robot and the other comprised two types of doors and a drawer, a device developed specially for this IA, and a humanoid robot. We also verified the effectiveness of the IA experimentally.

We have been developing a casting manipulator that includes a flexible light wire in the link mechanism to enlarge the workspace of the manipulator. In this paper we focus on the motion of collecting an object via casting manipulation. We propose a method of moving the object in the air by coordinating the motions of swinging the arm and winding the wire. Then, we develop a mechanical device that changes the apparent elasticity of the wire to transmit force to the object effectively. We also develop the motion generator that provides the optimal collect motion. We confirm the effectiveness of the proposed method through simulations. Finally, we conduct experiments using casting manipulator hardware and realize the quick motion of collecting the object.

This paper introduces a visual servoing scheme for humanoid walking. Though most of the existing approaches follow a perception-decision-action scheme, we close the loop so that the control is robust to model error. Our approach is based on a new reactive pattern generator which modifies, at the control level, the footsteps, the center of mass and the center of pressure trajectories for the center of mass to track a reference velocity. And, in this paper, the reference velocity is directly given by a visual servoing control law. Since, the HRP-2 walk induces a sway motion that disturbs the regulation of the visual control law, we introduce a control law allowing convergence in the image space and taking into account this sway motion.

A novel framework of biped walking stabilization control is introduced. The target robot is a 42 DOF humanoid robot HRP-4C which has a body dimensions close to the average Japanese female. We develop a body posture controller and foot force controllers on the joint position servo of the robot. By applying this posture/force control, we can regard the robot system as a simple linear inverted pendulum with ZMP delay. After a preliminary experiment to confirm the linear dynamics, we design a tracking controller for walking stabilization. It is evaluated in the experiments of HRP-4C walking and turning on a lab floor. The robot can also perform an outdoor walk on an uneven pavement.

This paper proposes a new framework to recover balance against external forces by combining disturbance suppression and reactive stepping. In the view point of the feedback control, a reactive step can help to diminish the disturbance caused by an external force that should be compensated to maintain balance. In other words, if the adequate step is performed, the feedback controller does not have to compensate all of the external force by itself. Under this concept, we propose an original solution to distribute the compensation between a feedback controller and a reactive step, according to the period of support phase and a disturbance characteristic. We first clearly distinguish between the role of the disturbance suppression and the reactive stepping. Then, based on this distinction, the small disturbance of external force or happening late during the single-support phase, is mainly suppressed by state feedback. The large disturbance which is out of capability by feedback controller and at the beginning of the single-support phase, is absorbed by modifying reactively the next steps. The proposed method is validated through experimental results with the HRP-2 humanoid robot.

This paper proposes a novel user interface for creating whole body motions of biped humanoid robots just by giving key poses. Although such an interface is popular for CG character animation, there have not been any practical systems that can appropriately handle the kinematic and dynamic conditions required for moving actual biped robots stably without falling down. In our interface, every time a key pose is created, modified or removed, the system immediately processes automatic trajectory adjustment of the feet and the waist so that the key poses and the interpolated motion can always meet the conditions. This enables a user to edit variety of motions in an intuitive and flexible way without paying attention to the conditions. We implemented the interface and confirmed that characteristic whole body motions of a realistic humanoid robot HRP-4C were easily created with it and the actual HRP-4C successfully performed them.

We address practical issues to develop reactive motion planning method capable of replanning the path online when the environment changes during the execution. By introducing planning and execution threads running in parallel, the robot can keep moving even during the replanning process as long as the motion is safe. The proposed method can be applied to discontinuous input of environmental changes that may occur due to incomplete perception. We then address a roadmap reuse method for efficient replanning to make use of the increasing knowledge about the environment, by introducing working and learning roadmaps. A general interface with robot motion controller is also defined so that the method can be applied to various types of robots. The proposed method is validated through planning simulations with moving obstacles.

A motion planning method for humanoid robots to pass under obstacles is proposed. The proposed motion planner can calculate a goal configuration and connect it with an initial configuration in a collision-free dynamically stable motion. The method can generate not only a body motion but also the footstep sequence. The effectiveness of the proposed method was validated by experiments with the humanoid robot HRP-2.

A method of regrasp planning for humanoid robot manipulation is proposed. We adopt pivoting manipulation for the humanoid robot to move a bulky object without lifting in a stable and dexterous manner. In order to carry the object to a desired place, the humanoid should sometimes move through narrow areas surrounded by obstacles. We propose a roadmap multiplexing planning to allow the robot to leave the object near narrow places and to regrasp it from another position to continue carrying. We utilize visibility probabilistic roadmap (PRM) method as a preprocessing to capture the critical configurations for regrasping. Then a diffusion method is employed to plan the overall manipulation path including regrasping. The proposed method is verified through planning simulation including whole-body motions.

There are many kinds of large, heavy objects, or objects with geometrical constraints in our daily life, but non-fixed robots such as humanoid robots are still not able to manipulate them sufficiently well. In this paper we focus on a swing door as a heavy object with geometrical constraints, and present a method for the humanoid robots to open it by using impulsive forces. We first discuss on momentum transfer from the robot to the door. Then we propose a method of generating a whole body motion to impact on the door. We analyze the dynamic model of the door, and we confirm the validity of our method through simulation. At last, we realize a motion of the robot opening a swing door quickly by the method in experiment with the HRP-2 robot hardware.

We propose a solution which combines haptic sensing with safe interaction, at low cost. Contact locations are made through a flexible sheet of tactile binary switch matrix. This sheet covers the surface of a rigid bumper module assembled to the robot's basic link through a distributed pressure sensing units. Combination of location and force provides the haptic sensing module. The haptic system is covered with a flexible outer material which role is to absorb contact impacts and to cast local surface profile on which the robot can take support. This overall system allows having a combined haptic sensing with safe and robust physical interaction with both the environment and the human using active compliance. We discuss the benefit of such a simple and modular concept and present how to design the cover material. A simple prototype is realized and experienced.

Abstract This paper deals with whole‐body motion planning and dynamic control for humanoid from two aspects: locomotion including manipulation and reaching. In the first part, we address a problem of simultaneous locomotion and manipulation planning that combines a geometric and kinematic motion planner with a dynamic humanoid motion generator. The second part deals with whole‐body reaching tasks by using a generalized inverse kinematics (IK) method to fully exploit the high redundancy of the humanoid robot. Through experiments using humanoid platform HRP‐2 No. 14 installed at LAAS‐CNRS, we first verify the validity of each method. An integrated experiment is then presented that unifies the both results via visual perception to execute an object‐fetching task. Copyright © 2009 John Wiley & Sons, Ltd.

This study proposes a complete solution to make the humanoid robot HRP-2 dynamically step over large obstacles. As compared with previous results using quasistatic stability, where the robot crosses over a 15-cm obstacle in 40 s, our solution allows HRP-2 to step over the same obstacle in 4 s. This approach allows the robot to clear obstacles as high as 21% of the robot's leg length (15 cm) while walking. Simulations show the possibility to step over an obstacle that is 35% of the length (25 cm) with a margin of 3 cm.

This paper emphasizes on the capacity of a humanoid robot to perform tasks that are difficult for other types of robots. It deals with manipulation of bulky objects. Such tasks require complicated manipulations involving the whole-body and fine coordination between legs, arms and torso motions. We introduce here a whole-body motion planner that allows a humanoid robot to autonomously plan a pivoting strategy that accounts for the various constraints: collision avoidance, legs-arms coordination and stability control. Based on a previous result by the authors [1] proving the small-time controllability of a pivoting system, the planner is proven to inherit from the probabilistic completeness of the samplingbased motion planning method it is built on. The geometric and kinematic capacity of the proposed planner is mainly demonstrated through simulations and experiments.

This paper addresses the problem of generating dynamic motion for a humanoid between two predefined postures. The humanoid robot starts its motion from a statically stable configuration to another known statically stable configuration when it is necessary to make step; that is, the center of mass (COM) is inside the support polygon at the initial and the goal configurations. A dynamic motion generation method is proposed in order to generate the whole-body robot motion. Zero moment point preview control is used for maintaining dynamic stability while the robot is taking the step and suitable splines are used for generating the hands, neck and foot motion because it is a free motion on the field of gravity; the screw theory is applied under Lie groups for kinematics and dynamics humanoid modeling, which allows smooth and natural humanoid motion. Successful results on the HRP-2 humanoid robot are shown and discussed.

A motion control method of lifting a heavy object up to a higher position with humanoid robots is developed. The key issue of lifting motion is how to reduce the load on humanoid arms in which low-power actuators are implemented. The use of singular postures of arms is well-known to avoid actuator saturation of the arms. By combining two different kinds of humanoid motions such as accelerating an object upward and sliding the body into under the object, we propose a method that enables to transit one singular posture of arms to another while lifting the object. Simulation results show the effectiveness of the proposed method for reducing the load on the arms. We realize a motion of lifting a heavy object dynamically with the humanoid robot HRP-2 through experiment.

In multimodal tele-cooperation as considered in this paper two humans in distant locations jointly perform a task requiring multimodal including haptic feedback. One human operator teleoperates a remotely placed humanoid robot which is collocated with the human cooperator. Time delay in the communication channel as destabilizing factor is one of the multiple challenges associated with such a tele-cooperation setup. In this paper we employ a control architecture with force-position exchange accounting for the admittance type of the haptic input device and the telerobot, which both are position-based admittance controlled. Llewellynpsilas stability criteria are employed for the parameter tuning of the virtual impedances in the presence of time delay. The control strategy is successfully validated in an intercontinental tele-cooperation experiment with the humanoid telerobot HRP-2 located in Japan/Tsukuba and a multimodal human-system-interface located in Germany/Munich, see also the corresponding video submission. The proposed setup gives rise to a large number of exciting new research questions to be addressed in the future.

The video shows an intercontinental cooperative telemanipulation task, whereby the operator site is located in Munich, Germany and the teleoperator site in Tsukuba, Japan. The human operator controls a remotely located teleoperator, which performs a task in the remote environment. Hereby the human operator is assisted by another person located at the remote site. The task consists in jointly grasping an object, moving it to a new position and finally releasing it, see Fig. 1.

Structuring methods of ambient intelligence are becoming important issue in robotics field; such ambient intelligence can enable robots to adopt ubiquitous computing technologies by using GPS and the RFID tag, acquire the necessary information for working in offices and houses, and thereby work accordingly. There are two merits in putting information into an environment. Firstly, persons who develop each robot can minimize the installation of knowledge of the objects that the robot may use. The new knowledge of the objects are provided by the manufacturers of the object and the owners, designers, architects, or removers who structure the environment whenever the ambience changes. Secondly, in case of different robots, the same ambient intelligence can handle different kinds of robots. No one needs to customize each robot. Each robot is able to execute tasks using the common ambient intelligence.

We have developed a casting manipulator that includes a flexible light string in the link mechanism to enlarge the workspace of the manipulator. In the casting manipulation, an end-effector is launched to its target by releasing the string connected to it, and its trajectory is controlled by the tension of the string. In this paper, we present the midair control of the end-effector. As a simple way, we propose the braking technique to apply impulsive force to the end-effector by braking the movement of the string. Examining dynamic characteristics of the string when an impulsive force applies to it, we show that the midair motion of the end-effector can be controlled by the braking technique. Then, we apply the braking technique to the multiple braking control of the trajectory. We confirm the effectiveness of the proposed method through simulations and experiments using casting manipulator hardware.

We propose a general and practical planning framework for generating 3-D collision-free motions that take complex robot dynamics into account. The framework consists of two stages that are applied iteratively. In the first stage, a collision-free path is obtained through efficient geometric and kinematic sampling-based motion planning. In the second stage, the path is transformed into dynamically executable robot trajectories by dedicated dynamic motion generators. In the proposed iterative method, those dynamic trajectories are sent back again to the first stage to check for collisions. Depending on the application, temporal or spatial reshaping methods are used to treat detected collisions. Temporal reshaping adjusts the velocity, whereas spatial reshaping deforms the path itself. We demonstrate the effectiveness of the proposed method through examples of a space manipulator with highly nonlinear dynamics and a humanoid robot executing dynamic manipulation and locomotion at the same time.

This paper describes a motion generation method for dynamic lifting by a humanoid robot. The proposed technique suggests the possibility of taking advantage of the whole body motion in order to facilitate the lifting movement. In particular, the idea is to perform a preliminary motion in order to generate a momentum which is instantaneously transferred to the object as an impulsive force. This allows the humanoid to lift up an object that could not be lifted up only by continuous force. However an impulsive force may make the humanoid unstable. Then, we propose to set the center of percussion (CoPn) of the whole system at the center of the support polygon of the humanoid when it lifts up the object. We also propose a design method of a preliminary motion of the humanoid that generates a sufficient momentum to lift up an object without any slip, tumble and hop of the whole system. The effectiveness of the proposed method is confirmed by simulation and experiment.

In this paper, we apply a general framework for building complex whole-body control for highly redundant robot, and we propose to implement it for visually-guided grasping while walking on a humanoid robot. The key idea is to divide the control into several sensor-based control tasks that are simultaneously executed by a general structure called stack of tasks. This structure enables a very simple access for task sequencing, and can be used for task-level control. This framework was applied for a visual servoing task. The robot walks along a planned path, keeping the specified object in the middle of its field of view and finally, when it is close enough, the robot grasps the object while walking.

This video demonstrates our current investigation in developing autonomous behaviors for humanoid robots. Our main goal is to develop functionalities as much generic as possible in order to realize useful behaviors. More particularly this video demonstrates our current status on extending a popular zero momentum problem (ZMP) preview control based pattern generator, and building some links between walking with vision.

This paper presents an object active visual search behavior in a 3D environment performed by a HRP-2 humanoid robot. The search is formalized as an optimization problem in which the goal is to maximize the target detection probability while minimizing the energy/distance and time to achieve the task. Natural constraints on the camera parameter space based on the characteristics of the recognition system are used to reduce the dimension of the problem and to speed up the optimization process to achieve a real time behavior. We present simulation and real experimental results using an HRP-2 robot.

Pivoting manipulation has such advantages as dexterity and safety over other methods to move bulky or heavy objects. In this paper we aim to show that a polyhedral object can be displaced to arbitrary position and orientation on a plane (i.e. such a pivoting system is controllable). More than that we show it is small time controllable, i.e. the reachable space from a starting point contains always a neighbor no matter how cluttered the environment is. As a consequence of this analysis, we propose a steering method to plan a manipulation path to be performed by a humanoid robot: first we use a classical nonholonomic path planner that accounts for the robot motion constraints, and then we transform that path into a sequence of pivoting operations. While the feasibility of elementary pivoting tasks has been already experienced by the humanoid robot HRP-2, we present here the very first simulations of the plans generated by our steering method.

This paper introduces a framework for whole-body motion generation integrating operator's control and robot's autonomous functions during online control of humanoid robots. Humanoid robots are biped machines that usually possess multiple degrees of freedom (DOF). The complexity of their structure and the difficulty in maintaining postural stability make the whole-body control of humanoid robots fundamentally different from fixed-base manipulators. Getting hints from human conscious and subconscious motion generations, the authors propose a method of generating whole-body motions that integrates the operator's command input and the robot's autonomous functions. Instead of giving commands to all the joints all the time, the operator selects only the necessary points of the humanoid robot's body for manipulation. This paper first explains the concept of the system and the framework for integrating operator's command and autonomous functions in whole-body motion generation. Using the framework, autonomous functions were constructed for maintaining postural stability constraint while satisfying the desired trajectory of operation points, including the feet, while interacting with the environment. Finally, this paper reports on the implementation of the proposed method to teleoperate two 30-DOF humanoid robots, HRP-1S and HRP-2, by using only two 3-DOF joysticks. Experiments teleoperating the two robots are reported to verify the effectiveness of the proposed method.

For planning and implementation of manipulation tasks using one or two arms/hands of a humanoid robot, which would be the most common application of the robot in the future, it is undoubtedly important to know the workspace of the robot. In this paper, we study the reachable space or boundary of an arm/hand when the humanoid robot stands on the ground with its two feet fixed. Since a humanoid robot has more degrees of freedom than a traditional robot and special characters that the latter does not possess, it would be very difficult or impractical to use conventional methods to analyze and obtain its reachable space. Here we propose a numerical approach to analyze and generate humanoid reachable space. Taking into account the robot balance, the geometric and kinematic constraints, we use optimization technique to build mathematic models for the reachable boundary. This discrete method gives rise to an approximation of the reachable space though, it is adequate for practical application. The proposed algorithm is illustrated by an example conducted on the humanoid platform HRP-2, and can be extended to more complex cases

In view of the importance of workspace to robotic motion planning and control, we study the reachable space of a humanoid robot in standing postures. Since it would be very difficult or impractical to use conventional analytical method to analyze and obtain the workspace of a humanoid robot, we present a numerical approach in this paper using the Monte Carlo method. As a random sampling numerical method, the Monte Carlo method is relatively simple and flexible to apply, and hence is suitable for the workspace generation of a humanoid robot. After formulating the basic constraints that a humanoid robot must satisfy in a manipulation task to enable the Monte Carlo method in generation of the reachable space, we present the algorithm and a method to build a database for utilization of the numerical results in application. We illustrate this method by an example conducted on the humanoid platform HRP-2. The results show that this method is feasible and practical for the generation and visualization of workspace of a humanoid robot

This paper deals with the generation of motion pattern for humanoid robots vertical jump. The study concentrates on the landing phase of the jump which is the most demanding for the system because of high discontinuity of acceleration at impact time. We first decompose the motion in two functions. The first one starts just before landing and consists in maximizing the value of the discontinuity by reducing the feet/ground velocity. We set the feet, COM and feet/COM velocities according to the supposed height of the jump. At impact time, the second function uses measured data of ground reaction force (GRF) from the ankle force sensors to quickly stop the system while keeping its vertical equilibrium. The influence of each function and their respective parameters is discussed and analyzed, and their validity is tested using the model of an existing humanoid platform

This paper addresses the role of toe joints in increasing the walking speed of biped robots. It is worthy that adding a toe joint will increase the step length thanks to the additional degree of freedom. But, the originality of this work is that longer steps are obtained thanks to an under-actuated phase and an appropriate ZMP trajectory. The simulations showed that adding passive toe joints allows smoother and 1.5 faster walking

Humanoid robotics and SLAM (simultaneous localisation and mapping) are certainly two of the most significant themes of the current worldwide robotics research effort, but the two fields have up until now largely run independent parallel paths, despite the obvious benefit to be gained in joining the two. The next major step forward in humanoid robotics will be increased autonomy, and the ability of a robot to create its own world map on the fly will be a significant enabling technology. Meanwhile, SLAM techniques have found most success with robot platforms and sensor configurations which are outside of the humanoid domain. Humanoid robots move with high linear and angular accelerations in full 3D, and normally only vision is available as an outward-looking sensor. Building on recently published work on monocular SLAM using vision, and on pattern generation, we show that real-time SLAM for a humanoid can indeed be achieved. Using HRP-2, we present results in which a sparse 3D map of visual landmarks is acquired on the fly using a single camera and demonstrated loop closing and drift-free 3D motion estimation within a typical cluttered indoor environment. This is achieved by tightly coupling the pattern generator, the robot odometry and inertial sensing to aid visual mapping within a standard EKF framework. To our knowledge this is the first implementation of real-time 3D SLAM for a humanoid robot able to demonstrate loop closing

This paper presents a 3D object recognition method based on spin-images for a humanoid robot having a stereoscopic vision system. Spin-images have been proposed to search CAD models database, and use 3D range informations. In this context, the use of a vision system is taken into account through a multi-resolution approach. A method for quickly computing multi-resolution and interpolating spin-images is proposed. The results on simulation and on real data are given, and show the effectiveness of this method

In this paper we address smooth and collision-free whole-body motion planning for humanoid robots. A two-stage iterative planning framework is introduced where geometric motion planner and dynamic pattern generator interacts by exchanging the trajectory, to obtain 3D whole-body dynamic motions simultaneous tasks including locomotion, in complex environments. We propose a practical method for smooth motion reshaping to avoid collisions in generated dynamic motion. Based on motion editing techniques in computer graphics animation, smooth collision-avoiding motion is generated through trajectory deformation. The validity of the proposed reshaping method is verified by computer simulations and experiments using humanoid platform HRP-2

The wide potential applications of humanoid robots require that the robots can walk in complex environments and overcome various obstacles. To this end, we address the problem of humanoid robots stepping over obstacles in this paper. We focus on two aspects, which are feasibility analysis and motion planning. The former determines whether a robot can step over a given obstacle, and the latter discusses how to step over, if feasible, by planning appropriate motions for the robot. We systematically examine both of these aspects. In the feasibility analysis, using an optimization technique, we cast the problem into global optimization models with nonlinear constraints, including collision-free and balance constraints. The solutions to the optimization models yield answers to the possibility of stepping over obstacles under some assumptions. The presented approach for feasibility provides not only a priori knowledge and a database to implement stepping over obstacles, but also a tool to evaluate and compare the mobility of humanoid robots. In motion planning, we present an algorithm to generate suitable trajectories of the feet and the waist of the robot using heuristic methodology, based on the results of the feasibility analysis. We decompose the body motion of the robot into two parts, corresponding to the lower body and upper body of the robot, to meet the collision-free and balance constraints. This novel planning method is adaptive to obstacle sizes, and is, hence, oriented to autonomous stepping over by humanoid robots guided by vision or other range finders. Its effectiveness is verified by simulations and experiments on our humanoid platform HRP-2.

The wide and potential applications of humanoid robots require that the robots can walk in complex environments cluttered with various obstacles. In such environments, the robots often need to overcome obstacles by stepping-over, stepping-on/down, or stepping-around. Before the implementation, it must be made sure whether the robots can do so, which is the so-called feasibility. In this paper, we give a more thorough feasibility analysis and more practical results of stepping-over and stepping-on/down, by extending our previous analyses in 2-D case to 3-D motion of the robot. Considering the geometry of the obstacle, the shapes and sizes, and kinematics of the robot legs, we use optimization technique to build corresponding models with nonlinear constraints (including those on collision avoidance and robot balance) to find the maximum height of the obstacle that the robot can step over or on/down. The results can be used as a prior knowledge and a database for motion planning of obstacle overcoming. The feasibility also provides an approach for evaluating the humanoid capability of obstacle overcoming.

This article explains a control system, which stabilizes running biped robot HRP-2LR. The robot uses prescribed running pattern calculated by resolved momentum control, and a running controller stabilizes the system against disturbances. The running controller consists of posture stabilization, inverted pendulum stabilization, contact torque control, impact absorbing control, foot vertical force control and torque distribution control. Applying the proposed controller, HRP-2LR could successfully run with average speed of 0.16(m/s) repeating flight phase of 0.06 (s) and support phase of 0.3 (s).

This paper proposes adapting human jumping dynamics to humanoid robotic structures. Data obtained from human jumping phases and decomposition together with ground reaction forces (GRF) are used as model references. Moreover, bodies inertial forces are used as task constraints while optimizing energy to determine the humanoid robot posture and improve its jumping performances.

Considering a stereoscopic visual system, this paper deals with the error involved by a 3D reconstruction process. If image pixels are seen as surfaces instead of points, interval analysis provides bounding boxes in which the reconstructed 3D point lies with certainty. This paper presents a method which refine this bounding box and gives a tighter approximation of the error. Using bisection, and a reprojection test in the image planes, the space in which the 3D reconstructed point may be located is given as an octree. This is achieved through the resolution of a set inversion problem using the SIVIA algorithm. For a lighter manipulation of the result, an englobing ellipsoid is deduced from this approximation. Finally the three models are tested on a recognition process for a humanoid robot.

In this paper, we present a method to control Kendama by casting manipulation. Casting manipulation is a technique to control an end-effector in the air by throwing the end-effector and controlling its ballistic flight using impulsive forces transmitted through a light string connected to the end-effector itself. First, we examine dynamic characteristics of a flexible string against impulsive force. We propose a method of identifying the viscoelastic model parameters of the string through free-fall experiments. Then the technique of braking the string is applied to the trajectory control with consideration of the time delay and slip of the brake. We conduct the rebound experiments by the braking technique to confirm its effectiveness. We analyse the work space where the suitable motion of end-effector for Kendama game is generated by multiple braking. Kendama game, motion of making the perforated ball impaled on the stick, is demonstrated by casting manipulator hardware.

In this paper, we address the problem of how a humanoid robot can step over a given obstacle. Obstacle stepping-over has two aspects, namely, feasibility analysis and motion planning. The former determines whether the robot can step over the obstacle, and the latter discusses how to realize the stepping-over, if it is feasible, by trajectory planning. The paper focuses on the latter. Specifically, based on our previous analysis of feasibility, we present a novel algorithm to plan suitable trajectories for obstacle stepping-over, taking into account two basic requirements. The first requirement is to avoid any collision between the robot and the obstacle, and the second to maintain stability or balance of the robot. To meet them, we decompose the whole body motion of the robot into two parts, corresponding to the upper body motion and the lower body, respectively. We first plan collision-free trajectories of the feet and the waist for lower body motion, and then adjust upper body motion by resolved momentum control to guarantee the robot stability. This novel planning method is adaptive to obstacle sizes and hence oriented to autonomous stepping-over of humanoid robots guided by vision or other range finders. Its effectiveness is shown by simulation and experiment on our humanoid platform HRP-2.

This work proposes a new style of manipulation by a humanoid robot. Focusing on the task of pushing an object, the foot placement of it is planed in real-time according to the result of manipulation of an object. By controlling the arms using the impedance control, a humanoid robot can push an object stably regardless of the mass of an object. If an object is heavy, a humanoid robot pushes an object with walking slowly, and vice versa. Also, for planning the gait in real-time, we newly propose an analytical method where the newly calculated trajectory of the robot motion is smoothly connected to the current one. The effectiveness of the proposed method is confirmed by simulation and experiment.

Aiming for a humanoid robot of the next generation, we have been developing a biped which can jump and run. This paper introduces biped robot HRP-2LR and its hopping with both legs as our first attempt towards running. Using a dynamic model of HRP-2LR, hopping patterns are pre-calculated so that it follows the desired profiles of the total linear and angular momentum. For this purpose we used resolved momentum control. Adding small modifications to negotiate the difference between the model and the real hardware, we successfully realized a steady hopping motion of 0.06 [s] flight phase and 0.5 [s] support phase. A hopping with forward velocity of 15 [mm/s] was also realized. Finally, a running pattern of 0.06 [s] flight and 03 [s] support phase was tested. HRP-2LR could successfully run with average speed of 0.16 [m/s].

This work studies locomotion planning of humanoid robots to pass through narrow spaces. Humanoid robots can alter the style of the locomotion while wheeled robots can not. The proposed method generates a 3D local map from visual information and plans the appropriate locomotion based on the map from biped walking with the variable height and the width and from crawling.

The goal of the study described In this work is to develop a total technology for archiving human dance motions. A key feature of this technology is a dance replay by a humanoid robot. Although human dance motions can be acquired by a motion capture system, a robot cannot exactly follow the captured data because of different body structure and physical properties between the human and the robot. In particular, leg motions are too constrained to be converted from the captured data because the legs must interact with the floor and keep dynamic balance within the mechanical constraints of current robots. To solve this problem, we have designed a symbolic description of leg motion primitives in a dance performance. Human dance actions are recognized as a sequence of primitives and the same actions of the robot can be regenerated from them. This framework is more reasonable than modifying the original motion to adapt the robot constraints. We have developed a system to generate feasible robot motions from a human performance, and realized a dance performance by the robot HRP-1S.

The establishment of an intuitive and effective whole body operation method is essential for the utilization of humanoid robots in real world tasks. Here we introduce a method for humanoid robot foot teleoperation, as a part of our whole body teleoperation system using only a simple joystick device. This paper explains a framework for real-time foot operation which incorporates the operator's foot command and robot's autonomy in maintaining balance. We describe the algorithm of an autonomous function which shifts the position of the robot's center of mass interactively based on the operator's command and the current feet condition of the robot. We report on successful experimental results of teleoperating a real humanoid robot HRP-2 using the proposed method.

It is believed that humanoid robots have better mobility than other mobile robots. However, little work has been reported on this mobility for nontrivial motion such as walking on rough terrains and overcoming obstacles. In this paper, we address the problem of obstacle overcoming by stepping-over, focusing on the feasibility analysis. That is, given an obstacle to overcome, we determine if the robot can step over it. In our analysis, we present a technique of global optimization under constraints to obtain the maximum height or width of an obstacle that the robot can step over while maintains the stability and avoids any collision between the robot legs and the obstacle. This analysis is a basis of motion planning for the robots to step over obstacles. It also provides an approach for evaluating the capability of obstacle overcoming of humanoid robots.

Aiming for a humanoid robot of the next generation, we have been developing a biped which can jump and run. This paper introduces a method of running pattern generation and running experiment of biped robot HRP-2LR. Based on the physical parameters of HRP-2LR, running patterns are pre-calculated so that it follows the desired profiles of the total linear and angular momentum. For this purpose we used resolved momentum control. The vertical momentum is calculated considering the compliant elements in order to realize accurate flight duration. The horizontal momentum is calculated to satisfy the ZMP patterns given in advance. Using our pattern, HRP-2LR could successfully run with average speed of 0.16[m/s] with repeat flight phase 0.06 [s] and support phase 0.3 [s].

This papers presents an application of interval analysis to a 3D reconstruction problem. The aim is to build a partial boundaries representation of an object including guaranteed information according to the camera model. Features points coordinates are described using intervals. This representation is used together with a method to search stereo correspondence based on the connectivity of segments.

In this paper, we will describe our attempt for a tele-operated humanoid robot to drive a backhoe. It will be possible for a humanoid robot to drive an industrial vehicle instead of a human operator. If a humanoid robot can be operated by a human operator from a remote site, it enables to use a general type of vehicle safely in a dangerous field. We introduced a backhoe as the target vehicle to show the possibility of driving a vehicle in a sitting posture. The robot sits down with balancing on a cockpit of the backhoe and manipulates control levers for driving. We developed a portable remote control device and remote control methods to operate the humanoid robot. For the evaluation, it is tested to sit down and manipulate the levers on the driving cockpit of the real backhoe. To compare it with a human's work, the efficiency is close to practical use.

We have developed a software platform, called OpenHRP, for humanoid robotics which consists of a dynamic simulator and motion control library for humanoid robots. This paper attempts to answer a frequently asked question "do the dynamic simulations and the experiments of biped walking of humanoid robots correspond?". Using OpenHRP and humanoid robots HRP-1S and HRP-2P, the comparisons between the simulations and experiments are shown at various aspects.

We introduce a new method of a biped walking pattern generation by using a preview control of the zero-moment point (ZMP). First, the dynamics of a biped robot is modeled as a running cart on a table which gives a convenient representation to treat ZMP. After reviewing conventional methods of ZMP based pattern generation, we formalize the problem as the design of a ZMP tracking servo controller. It is shown that we can realize such controller by adopting the preview control theory that uses the future reference. It is also shown that a preview controller can be used to compensate the ZMP error caused by the difference between a simple model and the precise multibody model. The effectiveness of the proposed method is demonstrated by a simulation of walking on spiral stairs.

This paper presents a humanoid robot that has the same size as a human and that can lie down to the floor and get up from the floor with the robot face upward and downward. We believe that the robot is the first life-size humanoid robot with the capability. The motions are realized by the combination of novel hardware and software. The features of the hardware are a human-like proportion and joints with wide movable ranges including two waist joints. The software segments the motion into the sequence of the contact states between the robot and the floor and assigns an appropriate controller to each transition between the consecutive states. The experimental results are presented.

This paper describes a possibility of a running humanoid robot based on the physical properties of an existing humanoid robot HRP-2L. To generate running motion, we develop a general method to control the total linear/angular momentum of a multi-link system. By this method, we can generate a reliable running pattern. Conducting simulations which take into account physical restrictions, we show that our humanoid robot can run at least at 0.5 m/s.

The goal of this study is a system for a robot to imitate human dances. This paper describes the process to generate whole body motions which can be performed by an actual biped humanoid robot. Human dance motions are acquired through a motion capturing system. We then extract symbolic representation which is made up of primitive motions: essential postures in arm motions and step primitives in leg motions. A joint angle sequence of the robot is generated according to these primitive motions. Then joint angles are modified to satisfy mechanical constraints of the robot. For balance control, the waist trajectory is moved to acquire dynamics consistency based on desired ZMP. The generated motion is tested on OpenHRP dynamics simulator. In our test, the Japanese folk dance, 'Jongara-bushi', was successfully performed by HRP-1S.

This paper proposes a new method for the teleoperation of humanoid robots which integrates human operator's intention with robot's autonomy. Getting hints from human conscious and subconscious motion generations, we propose a method which generates whole body motions of a humanoid robot satisfying operator's desired movement of specific points on which the operator focuses as well as the robot's balance. The proposed method is based on a whole body momentum control. We also introduce a function of automatic adjustments of the position of the center of mass and torso orientation in order to expand the reachable area of a humanoid robot. The effectiveness of the method is confirmed by using humanoid robot simulator OpenHRP with physical parameters of real humanoid robot HRP-1S.

This paper investigates a method through which human-size humanoid robot can fall over backwards safely. Squatting-extending motion of legs reduce impact of falling and shock-absorbing parts of the robot keep the force at a permissible range. The robot could stand up itself again after falling.

We introduce a method to generate whole body motion of a humanoid robot such that the resulted total linear/angular momenta become specified values. First, we derive a linear equation, which gives to total momentum of a robot from its physical parameters, the base link speed and the joint speeds. Constraints between the legs and the environment are also considered. The whole body motion is calculated from a given momentum reference by using a pseudo-inverse of the inertia matrix. As examples, we generated the kicking and walking motions and tested on the actual humanoid robot HRP-2. This method, the resolved momentum control, gives us a unified framework to generate various maneuvers of humanoid robots.

This paper presents a whole body teleoperation system for a humanoid robot integrating operator's intention and the robot's autonomy. Instead of giving command to all the joints of the body, we have been proposing a switching command based teleoperation system of which the operator selects only the necessary points of the robot's body to manipulate depending on the required tasks. We have also proposed a whole body motion generation method, which satisfies both, and the desired movement of specific points of the robot's body and the robot's balance constraint. This paper first explains the concept of the proposed teleoperation system and the autonomous functions for maintaining balance and expanding the reachable area of a humanoid robot. Then the paper reports on the experimental results using the proposed methods to teleoperate a real humanoid robot HRP-1S to perform balanced whole body motions satisfying operator's input command.

This is the first successful trial in the world to remotely control a humanoid robot so as to drive an industrial vehicle (backhoe) outdoors in lieu of human operator. Furthermore, the robot's operation was controlled while having it wear protective clothing to protect it against the rain and dust outside. This is too marks a world-first success demonstrating the humanoid robot's capability of performing outdoor work even in the rain. These results were achieved thanks to the development of the following three technologies: (1) the "remote control technology" for instructing the humanoid robot to perform total body movements under remote control and the "remote control system" for executing the remote control tasks; (2) the "protection technology" for protecting the humanoid robot against shock and vibrations of its operating sets and against the influences of the natural environment such as rain and dust; and (3) "full-body operation control technology" for controlling the humanoid robot's total capability to prevent the robot from falling over. The humanoid robot has a promising application potential for restoration work in environments struck by catastrophes and in civil engineering and construction project sites where it can "work" safely and smoothly.

We have been developing new abilities of humanoid robots to realize proxy driving of a lift truck. Construction machines such as a lift truck play an important role in many tasks, but sometimes the environments are too hazardous for human operators. If a tele-operated humanoid robot can drive a construction machine, it can work at a dangerous place. This humanoid robot operator has two advantages over an automated construction machine. It is much easier to carry the robot to a disaster site than moving the special construction machine. Besides, the robot may be less expensive than developing the special automated machine whose required number is relatively small. We have been developing new abilities of the tele-operated humanoid robot HRP-1 to realize the application. The paper describes results of investigations and experiments for proxy driving of a lift truck by HRP-1.

For real-time walking control of a biped robot, we analyze the dynamics of a three-dimensional inverted pendulum whose motions are constrained onto an arbitrarily defined plane. This analysis leads us a simple linear dynamics, the Three-Dimensional Linear Inverted Pendulum Mode (3D-LIPM). Geometric nature of trajectories under the 3D-LIPM is discussed, and an algorithm for walking pattern generation is presented. Experimental results of real-time walking control of a 12-DOF biped robot HRP-2L using an input device such as a game pad are also shown.

A method of running pattern generation for a humanoid robot using the dynamics of a simple inverted pendulum is proposed. The dynamic simulation using a model of an actual humanoid robot shows that the robot can run by applying a generated pattern with slight modifications. The simulation is used to evaluate the required performance of the actuators for an actual running robot.

This paper introduces an open architecture humanoid robotics platform (OpenHRP) on which various building blocks of humanoid robotics can be investigated. OpenHRP is a virtual humanoid robot platform with a compatible humanoid robot, and consists of a simulator of humanoid robots and motion control library for them which can also be applied to a compatible humanoid robot as it is. OpenHRP is expected to initiate the exploration of humanoid robotics on an open architecture software and hardware, due to the unification of the controllers and the examined consistency between the simulator and a real humanoid robot.

This paper presents an advanced leg module developed for HRP-2. HRP-2 is a new humanoid robotics platform,. which we have been developing in phase two of HRP. HRP is a humanoid robotics project, which has been launched by Ministry of Economy, Trade and Industry (METI) of Japan from 1998FY to 2002FY for five years. The ability of the biped locomotion of HRP-2 is improved so that HRP-2 can cope with rough terrain in the open air and can prevent the possible damages to a humanoid robot's own self in the event of tipping over. In this paper the mechanisms and specifications of leg module, electrical system, simulation results utilized for deciding specifications, and experimental results are also introduced.

This paper investigates a method to minimize damage to a humanoid robot when it falls over to the ground. The strategy involves controlling the attitude of the robot while it is falling over so that it lands on the ground at one of shock-absorbing parts of the robot. A simulation study has confirmed that the proposed algorithm can make the robot land at specified shock-absorbing parts.

This paper presents a method for importing human dance motion into humanoid robots through visual observation. The human motion data is acquired from a motion capture system consisting of 8 cameras and 8 PC clusters. Then the whole motion sequence is divided into motion elements and clustered into groups according to the correlation of end-effector trajectories. We call these segments 'motion primitives'. New dance motions are generated by concatenating these motion primitives. We are also trying to make a humanoid dance these original or generated motions using inverse-kinematics and dynamic balancing techniques.

A teleoperation system for whole body motions of a humanoid robot using a simple joystick master device is developed. Humanoid robots are physically similar to humans and usually possess a large number of degrees of freedom. By using hints from the shifting of the focus of attention for body motions between the joints of the human body during task executions, we propose a switching command based teleoperation system in which the operator selects only the necessary point of the humanoid robot's body for manipulation. In this paper, we present the implementation of this switching command based teleoperation system and experimental results using this system to teleoperate the humanoid robot HRP-1S developed in the Humanoid Robotics Project of the Ministry of Economy, Trade and Industry of Japan.

A balance control method for a humanoid robot is presented. It consists of a contact torque controller which is designed to have a good backdrivability and a feedback control of the total angular momentum and the center of gravity of a robot. A simulation result of a balance control using a 26 DOF humanoid robot model is shown.

Presents the utilization of inertial effect in damping-based posture control of a mobile manipulator. As a measure for redundancy resolution of a mobile manipulator, an effective inertia at the end effector in the operational space is proposed and investigated. By changing the effective inertia property via null-motion, we can get the reduced inertial property of the mobile manipulator. The reduced effective inertia has a significant effect on reducing the impulse force in collision with the environment. To find a posture satisfying both the reduced inertia and joint limit constraints, we propose a combined potential function method which can deal with multiple constraints. The proposed reduced inertia property algorithm is integrated into a damping controller to reduce the impulse force at collision and to regulate the contact force in mobile manipulation.

For 3D walking control of a biped robot we analyze the dynamics of a 3D inverted pendulum in which motion is constrained to move along an arbitrarily defined plane. This analysis yields a simple linear dynamics, the 3D linear inverted pendulum mode (3D-LIPM). Geometric nature of trajectories under the 3D-LIPM and a method for walking pattern generation are discussed. A simulation result of a walking control using a 12-DOF biped robot model is also shown.

Deals with the reduced inertial effect in damping-based posture control of a mobile manipulator. As a measure for redundancy resolution of a mobile manipulator, an effective inertia at the end effector in the operational space is proposed and investigated. The reduced effective inertia has a significant effect on reducing the impulse force in collision with environment. To find a posture satisfying both the reduced inertia and joint limit constraints, we propose a combined potential function method that can deal with multiple constraints. The proposed reduced inertia property algorithm is integrated into a damping controller to reduce the impulse force at collision and to regulate the contact force in mobile manipulation. The experimental results show that the reduced inertial effect of the mobile manipulator alleviates the impact force at collision.

Biped robots have better mobility than conventional wheeled robots, but they tend to tip over easily. To be able to walk stably in various environments, such as on rough terrain, up and down slopes, or in regions containing obstacles, it is necessary for the robot to adapt to the ground conditions with a foot motion, and maintain its stability with a torso motion. When the ground conditions and stability constraint are satisfied, it is desirable to select a walking pattern that requires small torque and velocity of the joint actuators. We first formulate the constraints of the foot motion parameters. By varying the values of the constraint parameters, we can produce different types of foot motion to adapt to ground conditions. We then propose a method for formulating the problem of the smooth hip motion with the largest stability margin using only two parameters, and derive the hip trajectory by iterative computation. Finally, the correlation between the actuator specifications and the walking patterns is described through simulation studies, and the effectiveness of the proposed methods is confirmed by simulation examples and experimental results.

We have been developing a casting manipulator which includes flexible string in the link mechanism to enlarge the work space of the manipulator. In the casting manipulation, a gripper is thrown to its target by releasing the string at a suitable time after generating enough motion of the gripper by swinging. In the paper we deal with the midair motion control of the gripper after throwing it for catching a target. First, we point out the necessity of controlling the gripper in midair after throwing it. Then we propose the utilization of an impulsive force applied to the gripper in the air by restricting and releasing the motion of the string. Investigating the impulsive force generation through experiments, we proposed the plural braking control of the gripper and confirmed the effectiveness of the method by simulation results.

Since a biped robot tends to tip over easily, stable and reliable biped walking is a very important achievement. In this paper, we propose a balance control method based on an off-line planned walking pattern with real-time modification. First, a method of generating a highly stable, smooth walking pattern is presented. Then, a method of real-time modification consisting of body posture control, actual zero moment point control and landing time control based sensor information is proposed. By combining the proposed off-line walking pattern with real-time modification, the biped robot can walk smoothly and adapt to unknown environments. The effectiveness of the proposed method is confirmed by dynamic simulator such as walking on unexpected irregular rough terrain, soft ground and in environments in the presence of disturbances.

Biped robots have better mobility than conventional wheeled robots, but they tip over easily. In order to walk stably in various environments such as rough terrain, up and down slopes, or regions containing obstacles, it is desirable to adapt to such ground conditions with a suitable foot motion, and maintain the stability of the robot by a smooth hip motion. We propose a method to plan a walking pattern consisting of a foot trajectory and a hip trajectory. First, we formulate the constraints of a foot trajectory, and generate the foot trajectory by 3rd order spline interpolation. By setting the values of constraint parameters, it is easy to produce different types of foot motion. Then, we formulate a hip trajectory using a 3rd order periodic spline function, and derive the hip trajectory with high stability. Finally, the effectiveness of the proposed method is illustrated by simulation examples.

Since most conventional robots cannot easily be adapted to environments designed for humans, a human-size biped robot is expected to be able to play an important role in assisting human activities. The selection of suitable joint actuators is an important point when developing a human-size biped robot. In order to select suitable actuators and effectively utilize the selected actuators, it is necessary to clarify the relationship between walking patterns and the specifications of each joint actuator, and this is the issue tackled in the paper. First, a method of generating a high stability, smooth walking pattern is presented, and it is shown how various walking patterns can be produced by setting a series of defined walking parameters. Then, the dynamics of the robot, including the reaction force between the feet and the ground, are formulated. Finally, by simulation studies, the correlation found between actuator specifications and walking patterns is described, and the effectiveness of the proposed method is suggested.

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.

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.

A new concept of a robot manipulator with passive mobile base is proposed which can be safely used in a human-robot cooperation environment. A joint-based control scheme is developed to control the end-effector position of the manipulator which is tolerant to unexpected contact force with the manipulator's environment. The mobility the of base of the manipulator is passively exploited to attenuate the dynamic disturbance of the contact force and the joint configurations are re-adjusted according to the evolution of the position of the base to maintain performance of the given task. Effectiveness of the proposed method is verified by computer simulation and experimental evaluation is currently underway.

A method of compliance control for ai redundant manipulator was proposed. The method is constructed by combining two different compliance control schemes; the fundamental compliance control in the joint space and the adjusting compliance control in the operational space. One of the features of the proposed method was the achievement of both the desired compliance condition in the operational space and the unique determination of the redundant manipulator configuration. Another feature of the method is that the inverse kinematic solution of the redundant manipulator was obtained only according to fundamental compliance parameters. Also, the determination of how to control the trajectory of the end- effector was introduced. The inverse kinematics solution is similarly obtained from the pseudo- inverse Jacobian matrix with a weight matrix. However, it has a different benefit from the pseudo-inverse approach, because it provides a function of adjusting the end-effector compliance as well as the inverse kinematics solution. Through experiments using a manufactured four degrees-of-freedom robotic arm which allowed redundancy, the efficiency of the method was confirmed.

A seven degrees of freedom manipulator actuated by a tendon drive system has been developed. In order to reduce the weight and volume of the manipulator, each motor was installed on the base frame and the motor torque was transmitted to each joint through a tendon-pulley system. For the tendon drive mechanism, a coupled drive mechanism was introduced, which actuates the manipulator mechanism by controlling the tension of each tendon in the tendon networks designed with coupled tendon structures. Eight direct-drive motors and tendon-pulleys are for a seven degrees of freedom manipulator. The structure of the manipulator developed is first explained then the tendon tension based control method for the coupled drive manipulator is formulated. Finally, through simple experiments using the manipulator in which the control system was installed, the effectiveness of the proposed structure and the control method are demonstrated.>

A new type of torque sensor is proposed for finger actuation with N actuators and tendons per N external degrees of freedom. The finger joint around a drive pulley is proportional to the tension difference on both ends of the pulley. Using a coupling mechanism between tendons, this tension difference can be measured directly without sensing individual tendon tensions. On the basis of this idea, a tension differential-type torque (TDT) sensor is proposed. With a single body of small size and fewer signal lines, the TDT sensor has several advantages over the conventional approach, which obtains the torque by attaching two tension sensors at both ends of the drive pulley and feeding sensor signals to a differential circuit. The basic principle of the TDT sensor is described, together with the design orientation. The dynamic and static characteristics are examined with the introduction of equivalent rotational stiffness, which is useful for examining system stability. The specially designed TDT sensors were implemented in a two-fingered robot hand, and the effectiveness of the sensor was confirmed.>

A control structure suitable for torque control using a geared DC servomotor discussed. The torque sensory feedback is advantageous for the fine torque generation by geared DC motors. However, it reduces the structural stiffness and in turn causes a low response in both the torque and position controls. To improve this, it is suggested that the natural frequency of the motor rotor position servosystem should be large. The suggestion is verified by experiments on a single-joint manipulator.>