Synthetic fiber ropes are widely used for robots because of their advantages such as lightweight, high tensile strength and flexibility. However, there is limited information on the physical properties of synthetic fiber ropes when used for robots. This study focuses on repetitive twisting of synthetic fiber ropes and provides information for selecting them for robots based on durability. To this end, we conducted repetitive twisting experiments on five types of ropes made from different fibers; we revealed that Dyneema has higher durability against repetitive twisting than the other ropes when a single rope is twisted. In addition, we conducted experiments on Dyneema by applying torsion to two ropes in parallel like a twisted string actuator. The result indicated that two Dyneema ropes in parallel have higher durability than a single rope; however, we revealed that the the tensile strength decreases sharply with an increase in the angle of twist.

A hydraulic drive system can generate a large force and is impact resistant. Thus, robots that utilize hydraulic drive systems have been developed for use in disaster areas. In a hydraulic drive system, it is necessary to design the motion of the robot within the capacity of the pump unit, but it is generally difficult to predict the required flow rate and pressure. Especially for hydraulically driven legged robots, the periodic significant changes in the required flow rate and pressure can make it difficult to select a pump and design the leg operation within pump capacity. Therefore, most operations are not designed in full consideration of the characteristics of the pump. By designing the operation of the robot considering the characteristics of the pump, improvements in energy efficiency and working speed can be expected. In this study, we theoretically derive the relationship between the leg motion of the hydraulic leg robot and the required pressure and flow rate. Based on the results, a method for designing the operation considering the characteristics of the pump is proposed, and its validity is experimentally confirmed.

Ionic polymer-metal composites (IPMC) actuators are popular because they can be driven at a low voltage, possess excellent responsiveness, and can perform soft motions similar to that of living creatures. Conventional IPMC soft robots are manufactured by cutting and assembling IPMC sheets. However, using this conventional process to stably manufacture three-dimensional (3D)-shaped soft robots is difficult. To mitigate this problem, we propose a new method for fabricating 3D IPMC actuators in which several surface electrodes are separately fabricated from a single ion-exchange membrane. We refer to our proposal as the simultaneous 3D forming and patterning (SFP) method. Unlike the conventional IPMC fabrication process, the SFP method requires only one step to fix the ion-exchange membrane to contact masks. First, we briefly describe IPMC actuators, before introducing the proposed SFP method in detail. Next, we describe our investigations of the patterning resolution for the surface electrode using the proposed method. We fabricated two soft robot prototypes using the proposed method. The first robot is a starfish-type soft robot. Its surface electrode can be patterned in a plane using the proposed method, and independent driving is possible by applying voltage individually to the divided electrodes. The second prototype is a sea anemone-type soft robot, wherein surface electrodes can be patterned on a 3D curved surface to form a 3D shape.

Among the various pneumatic actuators, thin McKibben muscles are particularly attractive owing to their high performance in terms of high contraction ratio, high flexibility, and productivity. One of the challenges for thin McKibben muscles and other pneumatic actuators is the fact that they generally need air hoses and air sources like compressors. This necessarily leads to bulky systems. To solve this problem, we propose and study a new approach to driving pneumatic actuators that exploits electrolysis/synthesis of water by a polymer electrolyte fuel cell (PEFC). This method could in-principle have high applicability to thin McKibben muscles. However, one challenge must still be addressed for the realization of an electrically driven thin McKibben muscle: the development of a tube-shaped soft PEFC. This paper proposes an electrically driven thin McKibben muscle with a tube-shaped soft PEFC realized through a flowing non-electrolytic plating method. First, the proposed thin McKibben muscle is briefly described. Then, a novel method for plating a tube-shaped soft PEFC using reflux is introduced, and its fundamental operation is tested. After the evaluation of the PEFC, we report a prototype realization of the proposed thin McKibben muscle. The developed prototype has a length of over 170 mm, a diameter of 4 mm, and high flexibility for bending. Finally, we elaborate on a driving experiment through which fundamental characteristics were experimentally evaluated. The prototype thin McKibben muscle succeeded in electrically controlling contraction and expansion motion with a flexible and bendable structure.

As a part of our research on several different types of Giacometti robots, a 20-m-long, considerably light, and simple robot arm, referred to as the Giacometti arm, is developed in this study. Even though the Giacometti arm is not suitable for precise positioning, rapid motion, and high load capacity, which are the aspects most conventional robots focus on, it is designed for extremely specific purposes such as the inspection of otherwise unreachable regions using a small camera at the arm's tip. In addition, it is designed to be essentially safe even if it falls down or hits an object. This aspect is realized using helium-filled balloon bodies and thin pneumatic muscles. In this paper, we designed new Giacometti arm which is 20-m-long, weighs 940 g, and has 20 degrees of freedom. To realize this long arm, we derived a kinematic model of the 20-m-long Giacometti arm, factoring in the air resistance. We verified the model using the arm, and its utility was confirmed at a mock-up facility.

In recent years, industrial robots have been applied to food production because of its huge potential market. Although cooking large amount of foods are done by specially designed cooking machines, dishing up the cooked foods remains as a labor-intensive task. To solve this problem, this paper proposes a new food handling gripper which is suitable for lunch box setout considering appetizing shape of presentation. A two degree-of-freedom multi-fingered gripper with a sliding push part was developed, and evaluated by grasping experiments with noodles and simmered foods. The gripper could put the food with a circular cone shape and control the amount of grasped food.

The crank wheel mechanism, consisting of a wheel mechanism and parallel links connected to each wheel, achieved high mobility and efficiency because it has both wheels and legs in a simple structure. However, each prior model of crank wheel mechanism has had shortcomings such as mass oscillation or fragile structure. In this paper, we propose a novel crank wheel mechanism, the “Eccentric Crank Rover”(ECR), which is an enhanced crank wheel mechanism with eccentric wheels. The eccentric wheels increase the under-body clearance, and change the body trajectory from straight to trochoid curve, which has the same shape as the crank legs but opposite phase trajectory. Thus, the body itself acts as a “second” crank leg. We experimentally confirmed higher step climbability, larger clearance, and lower cost of transport than other models such as normal wheel model, eccentric wheel model, and crank wheel model without eccentric wheel.

Unmanned rescue, observation and/or research vehicles with high terrain adaptability, high speed, and high reliability are needed to reach difficult locations. However, most vehicles achieve improved performance over rough terrain at the expense of low speed and/or complex mechanisms. We developed a blade-type crawler robot with a very simple and reliable mechanism, capable of traversing uneven terrain at high speed, using aerodynamic devices. As these small devices are in the low Reynolds number region, we tested a wing that made use of the ground effect. We experimentally confirmed the success of this approach in improving the traveling speed and ability to traverse uneven terrain. The robot with aerodynamic lift was climbed 1.5 times higher obstacle than without wings.

An amphibious all terrain mobile robot is required for disaster response tasks. In this paper, we propose “R-Crank”, which has a simple four wheels driving configuration with crank links, connecting to ipsilateral front and rear wheels so as to form parallel four-bar linkage systems. The crank links act as legs because their trajectory with respect to the ground become trochoid curve, which is commonly used as leg trajectories for a legged robot. These links achieve high terrain adaptability while maintaining simple structure of the wheeled robot. We developed a prototype model and carried out basic experiments. The robot achieved to climb 0.3 m of a step(76.9% of the wheel diameter), stairs and a snowy slope. In addition, we propose amphibious structure of crank links by installing multiple rigid paddles. The propulsive force generated by the crank links was measured and empirically derived the optimum parameters by using a small-sized experimental apparatus. Finally the robot equipped with the amphibious crank links achieved propulsion on water at 0.13 m/s. We also verified that the robot achieved going up and into water through stairs.

Development of intuitive user interface of a dexterous forceps with wrist joint for minimally-invasive surgery (MIS) is important for reducing the surgeon's confusion and fatigue. In this paper, a wearable robotic forceps manipulator is proposed. By measuring the wrist attitude of the surgeon by a motion sensor and driving the forceps tip by actuators, intuitive operation is realized, compared with fully mechanical forceps. A compact and lightweight system is achieved since we adopt pneumatic actuators to drive the manipulator. In order to help the force sensing of the surgeon, the external force is measured from the air pressure and displayed in a visual way. Experimental comparison with a conventional handheld forceps and a teleoperation system is conducted and its results show the effectiveness of the proposed handheld forceps.

Generally, wheel mechanisms are inferior to a tracked or walking mechanism in terms of step climbability or traversability in rough terrain; however, they are superior in terms of energy efficiency, structural simplicity, and carrying capacity. This paper proposes a new wheel mechanism, the swing-grouser wheel, which can climb high steps (especially in low friction environments) and has high energy efficiency. In addition, the swing-grouser wheel can climb regardless of the body inclination. Its merits are compared to the results of prior studies. Furthermore, the performance of the swing-grouser wheel was confirmed using a real device experiment and a 2D physics simulation, and improved using a full search of the parameters of the swing-grouser wheel. As a result, one improved parameter resulted in climbing at over 68% of the wheel diameter in a low friction environment; additionally, the energy efficiency was better than that of the previous model.

In this paper, a lightweight master interface for a surgical robot system is proposed. The position of the human hand is measured by a non-contact motion tracker, but the force feedback is realized by a handheld haptic device. A gripping force is displayed by a pneumatic bellows, which is smaller and more lightweight than electric motors. As for the slave manipulator, the gripper of a surgical forceps is actuated using a pneumatic cylinder. Force estimation is possible due to the back-drivability of the pneumatic actuator. Experimental results show the control performance of the haptic device and a constructed master-slave system.

Very long-reach snake-like robotic arms in the range of 14 meters are expected to be used in decommissioning work inside nuclear reactor containers. We developed a tendon-driven system which has the advantage of placing electronic devices protected in the arm's base part which stays out of the reactor container, and only few expensive highly radiation hardened sensors and tools are mounted in the arm tip. Generation of large joint torque is necessary to realize such a very long arm. We applied the concept of coupled tendon-driven mechanism formerly used to generate restricted two dimensional motions, and extended its concept by proposing a new joint arrangement which makes possible three dimensional motions in a large workspace. Mechanical design, compact storage method and derivation of the arm motion control are detailed. Moreover, we built a preliminary mechanical prototype called ”Mini 3D CT-Arm”, and the experimental results demonstrated the validity of the newly proposed concept.

In order to investigate under the sea, various types of underwater robots have been developed. However, most robots can only perform one type of moving such as screw, water gliding or walking, even though there are some creatures which use various types of locomotion in the wild life. Thus, we propose a new type of underwater robot, the “Glide Walker”, which can change its way of locomotion between gliding, walking and swimming depending on the situation. It can be performed by using its two wings with 3 DOFs each and its tail with 1 DOF. This article presents the basic concept, the moving strategy and the mechanical design of the robot in details. Moreover, it also presents the developed prototype, as well as the conducted experiments in which the robot was able to perform the three ways of locomotion successfully. Additionally, it also shows the high manipulation capability and the loop maneuver performance of the robot when in the swimming mode.

Unmanned rescue, observation and/or research vehicles with high terrain adaptability, fast velocity and high reliability to reach difficult rough terrain locations are still demanded, but most vehicles increase rough terrain adapt ability at the expense of low velocity and/or complex mechanisms. We propose a novel vehicle consisting of a very simple blade-type crawler and active antennas with rollers, resembling a wharf roach. This configuration assures stable travelling over uneven terrain at high-speeds, with a very simple and reliable mechanism. This article presents the basic concept, mechanical design of the crawler and the antennas, and the basic motion control strategies. Moreover, we built and tested the first small mechanical prototype named KEIOS-I, and got successful results from experiments on uneven terrain at a high-speed traveling, and also lateral travelling and jumping motions. Future work will also implement roller skating mode using the active antennas equipped with rollers.

In this paper, two types of biologically inspired educational robots based on gliding locomotion are presented. Gliding locomotion utilizes the difference between two orthogonal reaction forces to propel. Since this locomotion principle is very interesting and difficult to intuitively understand, its way of locomotion effectively evokes intellectual curiosity of students. One actuated degree of freedom (DOF) fish-like educational robot and its lecture program are developed for primary, junior high and high school students. And a snake-like educational robot which can connect arbitrary number of units, and its lecture program are developed for university students. We carried out these programs through several lectures. The results are also discussed in this paper.

Humanitarian demining aims at clearing landmine affected areas, but the current manual demining techniques are still slow, costly and dangerous. Discrimination methods for distinguishing between real mines and metal fragments would greatly increase efficiency of such demining operations, but none practical solution has been implemented yet. Important information for discrimination are the depth which targets are buried, so estimation methods of this physical property are desired. In this research, a new, accurate and fast method based on Spatially Represented Metal Mine Detector Signals for estimating metallic targets depths using Metal Mine Detectors is presented, which takes advantage of high precision scanning of the minefield using robotic manipulator.

In this paper, we discuss the development of the sprawling-type quadruped robot named “TITAN-XIII” and its dynamic walking algorithm. We develop an experimental quadruped robot especially designed for dynamic walking. Unlike dog-like robots, the prototype robot looks like a four-legged spider. As an experimental robot, we focus on the three basic concepts: lightweight, wide range of motion and ease of maintenance. To achieve these goals, we introduce a wire-driven mechanism using a synthetic fiber to transmit power to each axis making use of this wire-driven mechanism, we can locate the motors at the base of the leg, reducing, consequently, its inertia. Additionally, each part of the robot is unitized, and can be easily disassembled. As a dynamic walking algorithm, we proposed what we call “longitudinal acceleration trajectory”. This trajectory was applied to intermittent trot gait. The algorithm was tested with the developed robot, and its performance was confirmed through experiments.

A practical robot for search and rescue operation is demanded. We believe that one of the most promising robot is a snake-like robot with a slim and active trunk. This paper proposes a new multi-wheeled snake-like robot with active elastic trunk. We choose active wheels for the propulsive device due to mechanical robustness and simplicity, and increase locomotion capability by serially arranging many active wheels along to the trunk. We also propose a new mechanism for the trunk which satisfies both active bending motion and passive compliance. The active elastic trunk consists of deformable elastic segments made of sponge and rigid (or semi-rigid) segments, where active wheel is attached, stacked in layers. The active bending motion is generated by pulling the cables passing through the trunk from the head to tail. We develop three prototypes named “Souryu-VII”, “Souryu-VIII” and “Souryu-IX”. The mechanical design and features for each prototypes are explained and their performances are evaluated through the experiments with various measures.

A free rigid body dynamics simulator “Open Dynamics Engine” is empirically compared with the results of hardware measurements in joint torque/power dimensions for a quadruped robot “TITAN-VIII”. We developed the quadruped robot model on the simulator and compared simulated joint torques and powers with hardware experiments during walking which takes four different walking postures. The results suggest that the direct acquisitions of simulated joint torques include a large latency in our application but this defect is avoidable by using joint force information. Careful parameter settings and tunings permit the simulator to match hardware experimental data with sufficient accuracy.

Roller-Walker is a leg-wheel hybrid mobile robot using a passive wheel equipped on the tip of each leg. The passive wheel can be transformed into sole mode by rotating ankle roll joint when Roller-Walker walks on rough terrain. This paper discusses energy efficiency of locomotion in wheeled mode. We define a leg trajectory to produce forward straight propulsion and discuss the relationships between the parameters of the leg trajectory and energy efficiency of the propulsion using numerical simulator. We find optimum parameter sets where optimization criteria is specific resistance. Then we carried out hardware experiments and empirically derived experimental specific resistance. We show that wheeled locomotion has 8 times higher energy efficiency than ordinary crawl gait. Finally we compare the specific resistance of Roller-Walker with other walking robots described in the literatures.

Home oxygen therapy (HOT) is a medical treatment for patients suffering from severe lung diseases. Although walking outdoors is recommended for patients to maintain physical strength, patients always have to carry a portable oxygen supplier which is not sufficiently light weight for this purpose. Our ultimate goal is to develop a mobile robot to carry an oxygen tank and follow a patient in an urban outdoor environment. We have proposed a mobile robot with a tether interface to detect the relative position of the foregoing patient. In this paper, we improve mobile platform mechanisms and active wheels to maximize the step height which can be negotiated, and to allocate sufficient space in the main body to carry an actual oxygen tank. The following control algorithm is also improved and its effectiveness is demonstrated in an outdoor experiment.

We propose a new weight compensation mechanism with a non-circular pulley and a spring. We show the basic principle and numerical design method to derive the shape of the non-circular pulley. After demonstration of the weight compensation for an inverted/ordinary pendulum system, we extend the same mechanism to a parallel five-bar linkage system, analyzing the required torques using transposed Jacobian matrices. Finally, we develop a three degree of freedom manipulator with relatively small output actuators and verified that the weight compensation mechanism significantly contributes to decrease static torques to keep the same posture within manipulator's work space.

This paper describes a development of a light duty arm with an active-fingertip gripper for handling discoid objects. The system is potentially capable of sharing the workspace with human workers, assuming the use in a cell manufacturing system. We propose a new 3-DOF gripper mechanism with two fingers which symmetrically move in parallel and each finger has a 2-DOF fingertip of a cylindrical shape. We also develop a lightweight arm with a weight compensation mechanism which is composed of a non-circular pulley and a spring to minimize required actuator torque. After verification of basic performance, the hand-arm system successfully performs a pick-and-place task for a discoid object from horizontal placement to vertical placement and vice versa. We demonstrate continuous 100 times pick-and-place operations without failure where its cycle time almost equals to a human worker.

Foot mechanism of walking robots needs to adapt to rough terrain enough because the walking robot is requested to have the ability to walk stably on rugged ground. However, the foot mechanism of multi-leg walking robots have been often modeled as a point foot or a disc sole so far, and there is a problem that the robot can not fully use the sole area as a support polygon on rough terrain. To solve the problem, the terrain adaptive sole is developed which can adapt to the ground with small ruggedness and support the ankle moment to acquire stable footholds on uneven terrain. The terrain adaptive sole is composed of a deformation mechanism, a shape-fixing mechanism and a vertical force sensor, which are developed for quadruped walking robot TITAN VIII. The deformation mechanism changes the shape of the foot according to the terrain and the shape-fixing mechanism fixes the shape after the foot landing. These functions are achieved by a passive mechanism to be robust and lightweight. We demonstrate that TITAN VIII with the proposed terrain adaptive sole can successfully negotiate a rough terrain.

Roller-walker is a leg-wheel hybrid mobile robot using a passive wheel equipped on the tip of each leg. The passive wheel can be transformed into sole mode by rotating ankle roll joints when roller-walker walks on rough terrain. This paper describes adaptation of characteristics of the propulsion by a leg trajectory in the case of wheeled locomotion. Firstly, the authors demonstrate that Roller-Walker could achieve high-speed propulsion and slope climbing propulsion by simply changing parameters of the leg trajectory on the hardware experiments. Secondly, an asymptotic parameter tuning method is introduced to perform specified velocity on the different surfaces with different friction. The method is evaluated in numerical simulations. The results suggest that the method allows the Roller-Walker to have a function similar to an automatic transmission of a usual car.

Biological systems seem to have a simpler but more robust locomotion strategy than that of the existing biped walking controllers for humanoid robots. We show that a humanoid robot can step and walk using simple sinusoidal desired joint trajectories with their phase adjusted by a coupled oscillator model. We use the center-of-pressure location and velocity to detect the phase of the lateral robot dynamics. This phase information is used to modulate the desired joint trajectories. We do not explicitly use dynamical parameters of the humanoid robot. We hypothesize that a similar mechanism may exist in biological systems. We applied the proposed biologically inspired control strategy to our newly developed human-sized humanoid robot computational brain (CB) and a small size humanoid robot, enabling them to generate successful stepping and walking patterns.

We propose to improve the locomotive performance of humanoid robots by using approximated biped stepping and walking dynamics with reinforcement learning (RL). Although RL is a useful non-linear optimizer, it is usually difficult to apply RL to real robotic systems - due to the large number of iterations required to acquire suitable policies. In this study, we first approximated the dynamics by using data from a real robot, and then applied the estimated dynamics in RL in order to improve stepping and walking policies. Gaussian processes were used to approximate the dynamics. By using Gaussian processes, we could estimate a probability distribution of a target function with a given covariance function. Thus, RL can take the uncertainty of the approximated dynamics into account throughout the learning process. We show that we can improve stepping and walking policies by using a RL method with the approximated models both in simulated and real environments. Experimental validation on a real humanoid robot of the proposed

We show that a humanoid robot can step and walk using simple sinusoidal desired joint trajectories with their phase adjusted by a coupled oscillator model. We use the center of pressure location and velocity to detect the phase of the lateral robot dynamics. This phase information is used to modulate the desired joint trajectories. We applied the proposed control approach to our newly developed human sized humanoid robot and a small size humanoid robot developed by Sony, enabling them to generate successful stepping and walking patterns

Recently, there has been a growing interest in biologically inspired biped locomotion control with Central Pattern Generator (CPG). However, few experimental attempts on real hardware 3D humanoid robots have yet been made. Our goal in this paper is to present our achievement of 3D biped locomotion using a neural oscillator applied to a humanoid robot, QRIO. We employ reduced number of neural oscillators as the CPG model, along with a task space Cartesian coordinate system and utilizing entrainment property to establish stable walking gait. We verify robustness against lateral perturbation, through numerical simulation of stepping motion in place along the lateral plane. We then implemented it on the QRIO. It could successfully cope with unknown 3mm bump by autonomously adjusting its stepping period. Sagittal motion produced by a neural oscillator is introduced, and then overlapped with the lateral motion generator in realizing 3D biped locomotion on a QRIO humanoid robot.

We propose a model-based reinforcement learning algorithm for biped walking in which the robot learns to appropriately modulate an observed walking pattern. Via-points are detected from the observed walking trajectories using the minimum jerk criterion. The learning algorithm modulates the via-points as control actions to improve walking trajectories. This decision is based on a learned model of the Poincaré map of the periodic walking pattern. The model maps from a state in the single support phase and the control actions to a state in the next single support phase. We applied this approach to both a simulated robot model and an actual biped robot. We show that successful walking policies are acquired.

Humanoid research has made remarkable progress during the past 10 years. However, currently most humanoids use the target ZMP (zero moment point) control algorithm for bipedal locomotion, which requires precise modeling and actuation with high control gains. On the contrary, humans do not rely on such precise modeling and actuation. Our aim is to examine biologically related algorithms for bipedal locomotion that resemble human-like locomotion. This paper describes an empirical study of a neural oscillator for the control of biped locomotion. We propose a new neural oscillator arrangement applied to a compass-like biped robot. Dynamic simulations and experiments with a real biped robot were carried out and the controller performs steady walking for over 50 steps. Gait variations resulting in energy efficiency was made possible through the adjustment of only a single neural activity parameter. Aspects of adaptability and robustness of our approach are shown by allowing the robot to walk over terrains with varying surfaces with different frictional properties. Initial results suggesting optimal amplitude for dealing with perturbation are also presented.

We propose a framework for learning biped locomotion using dynamical movement primitives based on nonlinear oscillators. In our previous work, we suggested dynamical movement primitives as a central pattern generator (CPG) to learn biped locomotion from demonstration. We introduced an adaptation algorithm for the frequency of the oscillators based on phase resetting at the instance of heel strike and entrainment between the phase oscillator and mechanical system using feedback from the environment. In this paper, we empirically explore the role of phase resetting in the proposed algorithm for robust biped locomotion. We demonstrate that phase resetting contributes to robustness against external perturbations and environmental changes by numerical simulations and experiments with a physical biped robot.

We have proposed a leg-wheel hybrid mobile robot named "Roller-Walker". Roller-Walker is a vehicle with a special foot mechanism, which changes to a sole in walking mode and a passive wheel in skating mode. On rugged terrain the vehicle walks in leg mode, and on level or comparatively smooth terrain the vehicle makes wheeled locomotion by roller-skating using the passive wheels. The characteristics of Roller-Walker are: (1) it has a hybrid function but is lightweight, (2) it has the potential capability to exhibit high terrain adaptability in skating mode if the control method for roller-walking is fully investigated in the future. In the paper, the 4 leg trajectory of straight roller-walk is optimized in order to achieve maximum constant velocity. Also a steering roller-walk control method is proposed. It is obtained by the expansion of the straight roller-walk trajectory theory adding an offset to the swinging motion. This steering method resembles that of a car. The control system was modified into an untethered system, and control experiments were performed. The realization of the steering motion was verified by them.

We have proposed a new leg-wheel hybrid mobile robot named "Roller-Walker". Roller-Walker is a vehicle with a special foot mechanism which changes to a sole in walking mode and a passive wheel in skating mode. On rugged terrain the vehicle walks in leg mode, and on level or comparatively smooth terrain the vehicle makes,wheeled locomotion by roller-skating using the passive wheel. The characteristics of Roller-Walker are: 1) it has a hybrid function but is lightweight 2) it has the potential capability to exhibit high terrain adaptability in skating mode if the control method for roller-walking is fully investigated in the future. In this paper, the 2-leg trajectory for straight roller-walking is optimized in order to achieve the maximum constant velocity. Also a changeable ankle mechanism was integrated into the Roller-Walker system. Experiments were performed to demonstrate the validity of the concept of Roller-Walker and the results of straight roller-walk experiments are compared with those derived through simulation.

A snake is able to attain high terrain adaptability and versatile locomotion even though it has an extremely simple one-dimensional configuration. In order to utilize these functions for robotics, we have adapted the basic biological machine elements of the snake into the active cord mechanism (ACM). We have discussed the creeping dynamics and applications to manipulation. In this paper, we develop a new experimental model named "ACMR-R1" with a self-contained system, which realizes higher mobility and terrain adaptability compared with the past model. Next, gliding experiments on ice were carried out in order to demonstrate that the creeping motion is the same as the principle of skating. Finally, a new terrain adaptive control method for sloping surfaces is proposed, and we verified the effectiveness of it by slope climbing experiments.