This paper presents mechanical design and control of a bio-inspired legged robot. To achieve a fast legged running mechanism, a novel linkage leg structure is designed based on hind legs of domestic cats. The skeletomuscular system and parallel leg movement of a cat are analyzed and applied to determine the link parameters. The hierarchical control architecture is designed according to the biological data to generate and modulate desired gaits. The effectiveness of the leg mechanism design and control is verified experimentally. The legged robot runs at a speed of 46 km/h, which is comparatively higher speed than other existing legged robots.

This paper describes a study on posture control of the multi-legged biomimetic underwater robot (CALEB10). Because the underwater environment has a feature that all degrees of freedom are coupled to each other, we designed the posture control algorithm by separating each degree of freedom. Not only should the research on posture control of underwater robots be a precedent study for position control, but it is also necessary to compensate disturbance in each direction. In the research on the yaw directional posture control, we made the drag force generated by the stroke of the left leg and the right leg occur asymmetrically, in order that a rotational moment is generated along the yaw direction. In the composite swimming controller in which the controllers in each direction are combined, we designed the algorithm to determine the control weights in each direction according to the error angle along the yaw direction. The performance of the proposed posture control method is verified by a dynamical simulator and underwater experiments.

The CALEB10 is a multi-legged biomimetic underwater robot. In the last research, we developed a swimming pattern named ESPG (Extended Swimming Pattern Generator) by observing diving beetle’s swimming actions and experimented with a positive buoyancy state in which CALEB10 floats on the water. In this paper, however, we have experimented with CALEB10 in a neutral buoyancy state where it is completely immersed in water for pitch motion control experiment. And we found that CALEB10 was unstably swimming in the pitch direction in the neutral buoyancy state and analyzed that the reason was due to the weight proportion of the legs. In this paper, we propose a pitch motion control method to mimic the pitch motion of diving beetles and to solve the problem of CALEB10 unstably swimming in the pitch direction. To control the pitch motion, we use the method of controlling additional joints while swimming with the ESPG. The method of obtaining propulsive force by the motion of the leg has a problem of giving propulsive force in the reverse direction when swimming in the surge direction, but this new control method has an advantage that a propulsive moment generated by a swimming action only on a target pitch value. To demonstrate validity this new control method, we designed a dynamics-based simulator environment. And the control performance to the target pitch value was verified through simulation and underwater experiments.

In this study, we aim to develop energy efficient walking and running robot with compliant leg. So, we propose the energy efficient locomotion control method. And, we experiment the proposed control method applying to the experimental robot with compliant leg. From the experiment, we look at whether the proposed control method can the robot walk and run energy efficiently.

This paper presents the estimation of the frictional coefficient of the wheel-legged robot with hip joint actuation producing maximum tractive force. Slip behavior for wheel-legged robot is analytically explored and physically understood by identification of the non-slip condition and derivation of the torque limits satisfying it. Utilizing results of the analysis of slip behavior, the frictional coefficients of the wheel-legged robot during stance phase are numerically estimated and finally this paper suggests the pseudo-algorithm which can not only estimate the frictional coefficients of the wheel-legged robot, but also produce the candidate of the touch down angle for the next stance.

Mobile robots traveling on rough terrain need several algorithms to overcome obstacles. In this paper, we propose the step-type obstacle traversal algorithm to adapt the mobile robot with six arms and wheels to travel on rough terrain. Obstacle traversal is composed of two different stages: planning and control. In planning stage, the required joint torque of each arm as well as the interference between the wheels and the arms are analyzed to guarantee traversing obstacles. Control stage includes such steps as checking distance to obstacle, determining the height and length of obstacle, performing arm motion according to sensed torque data, and evaluating safety at every instance. The proposed algorithm is designed and implemented for CALEB 1 six legged robot developed in the laboratory and verified by simulation and experiment in outdoor environment.