Analysis of position-based impedance control method and the composition of system dynamic compliance

The hydraulic drive legged robot with high performance is introduced in this paper. When the robotic foot contacts the ground, the collision and impact can easily take place. Therefore, the robotic leg joint should possess certain compliance. In order to enhance the compliance of robotic leg joint, the paper researches the position-based impedance control method. Besides, the analysis for the composition of compliance is proposed, which lays the theoretical foundation for the dynamic compliance compensation control. To be specific, the force analysis for the hydraulic drive unit of robotic leg joint is conducted to research the method of impedance control and the impedance control link is introduced to the control system outer loop. Moreover, through building the mechanism model of hydraulic drive unit, the formula derivation and the theoretical analysis are conducted to obtain the series composition theory of system dynamic compliance. The control effect of impedance control method is verified through the experiment on the hydraulic drive unit performance test platform. The experiment proves the effectiveness of the position-based impedance control method for enhancing the compliance of hydraulic drive unit position control system as well as the series composition theory of system dynamic compliance. Thus, the research in this paper can give certain guiding significance to the dynamic compliance compensation control and the dynamic compliance compound control of the position control system in future.