Active Variable Impedance Control for Hydraulic-Driving Articulated Robotic Leg

Abstract

for quadruped, walking on irregular terrain may produce undesired instantaneous impact with ground and make robot unstable. To cope with the problem, in this paper, the active impedance algorithm is proposed. By one leg the laying of quadruped robot movement can be divided into three states, swing period, landing period and support period, and in different state in guarantee the foot end desired trajectory tracking accuracy according the virtual compliant leg model to choose the appropriate impedance Parameter. Experiment on the single leg was dropped from a height of 15cm onto the ground for two types of impedance variations (linear impedance and nonlinear impedance) in different landing period. The experiments have proved that the proposed algorithm can effectively reduce the instantaneous force when contacting with the ground under the premise of ensuring the tracking accuracy of the foot end trajectory, so as to achieve compliant foot-fall.