Research on impedance control based on force servo for single leg of hydraulic legged robot

A force servo based impedance controller that allows compliant behaviours of the leg of a hydraulic legged robot has been presented in this paper. A novel velocity compensation algorithm which makes for elimination of the redundant forces is also included. Their performance is assessed on a 2-DOF hydraulic leg whose kinematics and transfer functions have been modeled. A double hydraulic cylinders experiment platform is designed for performance testing of the force tracking of the hydraulic actuators. Experimental results have shown a good performance of the impedance controller which allows arbitrary virtual stiffness and damping of the leg.