Impedance Control System Analysis and Gain Tuning of Robot Joints with Flexibility

摘要

The cascaded impedance control structure with both inner torque feedback and outer position feedback loops, has become prevalent in robot joints with flexibility to achieve compliant interactions with environments and humans. However, since the commonly used controller gains design methods are based on optimizing the position tracking performance, these methods lack system impedance characteristics guarantees. By characterizing the system impedance in frequency domain by a transfer function, a gain tuning method is proposed in this paper, which directly adjusts the zeros and poles of the impedance transfer function to regulate the system impedance characteristics. Based on the analysis of the impedance transfer function, the gain tuning procedure is simplified by decreasing the number of parameters needed to be selected. The effectiveness of the proposed gain tuning method is validated by simulation.