Stability analysis of quadruped robot based on compliant control

Abstract

Stability is a key point in developing quadruped robot. In this paper, we focus on allowing heavy quadruped robot to be self-adaptive to various disturbances. The Spring Loaded Inverted Pendulum method is applied in regulating feet landing positions. Moreover, yaw motion is discussed to revise direction-deflection after disturbance of external force. In dynamics analysis, both inverse dynamics and balance controller are employed to predict desired torque of joints. Meanwhile gains of position controller can be decreased. The main contribution is an active compliant controller with respect to robot posture. According to linear functions, it can adjust four leg lengths separately to keep robot balance. Therefore, stability is kept both in torque level and position level. The simulation results prove the effect of proposed control scheme under disturbances of external force and uneven terrain. In summary, this control scheme is exceedingly useful in enhancing legged robot stability.