Fast Walking of Position-Controlled Biped Robot Based on Whole-Body Compliance Control.

When a biped robot walks at a high speed, only relying on the open-loop gait trajectory based on the linear inverted pendulum model (LIPM), the robot cannot maintain stability. Sudden contact with the ground when landing may cause the robot to be unstable. Simultaneously, when the robot walks faster, the horizontal position of the center of mass (CoM) varies greatly during a walk cycle, and the expected CoM trajectory cannot be accurately tracked, resulting in a deviation from the zero-moment point (ZMP). Aiming at the above situation that may occur in fast walking, a whole-body compliance controller with emphasis on making robot’s walking more stable and faster is presented in this paper. The whole-body compliance controller consists of three parts: the CoM compliance controller, the vertical compliance controller and the foot compliance controller, which are used to improve the tracking effect of CoM, reduce the force impact of foot, and adjust the posture of the foot respectively. The simulation results show that with the whole-body compliance controller proposed in this paper, the tracking accuracy of the CoM becomes better, the posture of the robot is more stable during walking, and the landing compliance during landing are greatly improved. Finally, the walking speed of the robot can reach 1.8m/s.