A Novel Impedance Control Based on Equivalent Stiffness for Hydraulic Single-leg Robot

This paper presents a proposed strategy for improving the position-tracking accuracy of force-based impedance control in hydraulic single-leg robots. Initially, the mechanical structure and drive system of the single-leg robot are introduced. Subsequently, a kinetic and dynamic model is developed to determine the desired position and force for each joint based on the given action. The proposed strategy, called equivalent stiffness impedance control, is then presented. It combines a penalty function and the stiffness of each joint near the desired position to calculate the equivalent stiffness. Simulations and experiments are conducted to evaluate the performance of the control strategy. The results demonstrate that the proposed strategy achieves fast response speed and high position tracking accuracy. Moreover, the mechanical characteristics near the desired position are comparable to traditional impedance control. This research provides valuable insights for impedance control in bionic-legged robots.