Force-feedback based active compliant position control strategy for a hydraulic quadruped robot

Most existing legged robots are developed under laboratory environments and, correspondingly, have good performance of locomotion. The robots' ability of walking on rough terrain is of great importance but is seldom achieved. Being compliant to external unperceived impacts is crucial since it is unavoidable that the slip, modeling errors and imprecise information of terrain will make planned trajectories to be followed with errors and unpredictable contacts. The impedance control gives an inspiration to realize an active compliance which allows the legged robots to follow reference trajectories and overcome external disturbances. In this paper, a novel impedance force/position control scheme is presented, which is based on Cartesian force measurement of leg's end effector for our hydraulic quadruped robot The simulation verifies the efficiency of the impedance model, and the experimental results at the end demonstrate the feasibility of the proposed control scheme.