Compliance Control and Analysis for Equivalent Hydraulic Legs

In this article, the compliant behavior of an equivalent hydraulic leg is achieved by combining active compliance control of hydraulic cylinder with a passive spring at its end effector. Firstly, a position-based active compliance control is proposed based on impedance control to reduce the contact impact. Secondly, the stability of proposed compliance controller and the range of impedances (Z-width) of compliance control are analyzed, and the design procedure of proposed compliance controller is given out. Finally, experimental results show that the contact impacts could be well handled by the proposed control method. This research provides an insight for the compliance control of hydraulic legged robots.