An approach to biped robot control according to surface condition of ground

This paper describes an approach of a biped robot control to realize a stable walking motion under a floor condition with an unknown slope. The slope angle is detected by the touch sensors mounted on the soles and encoders fixed on the joints. The tip trajectory of free swing leg and the position of the center of gravity are modified by the detected slope angle. In this paper, the biped robot is treated as a redundant manipulator and its configuration is achieved by the null space vector. This paper introduces a novel algorithm to determine the slope angle by utilizing the null space motion. Furthermore, the disturbance observer is employed as a disturbance compensator to make sure the total motion including the null space motion. The numerical and experimental results are also shown to confirm the validity of the proposed method.