Compliant Control for Variable Stiffness Actuator Based on Active Stiffness Regulation

Abstract

In response to the requirements for high-precision motion control and adaptive compliance in rehabilitation training and human-robot interaction scenarios, this paper proposes a hierarchical control strategy for a dual-motor-driven variable stiffness actuator (VSA), enabling coordinated control of position tracking and stiffness regulation. The position control is implemented within an impedance control framework, where a disturbance compensation mechanism is incorporated to enhance system robustness against nonlinearities and external disturbances. A continuous switching factor based on the human-robot interaction force is constructed, allowing the output stiffness to be smoothly adjusted across different interaction modes while avoiding abrupt variations. Simulation and experimental results demonstrate that the proposed approach achieves superior position-tracking accuracy compared with a conventional PD controller, and verifies its capability to realize continuous variable-stiffness regulation under varying interaction conditions. The proposed active stiffness regulation compliant controller (ASRCC) thus provides an effective solution for improving compliance and adaptive regulation of VSA in rehabilitation systems.