Torque control of a cable-driven series elastic actuator using the 2-DOF method

Abstract

Series elastic actuators (SEA) are playing an increasingly important role in the fields of rehabilitation robotics and physical human-robot interaction for their inherent compliance and safety. Cable-driven series elastic actuation has further advantages of low inertia, flexible installation, etc. In this paper, a cable-driven SEA platform has been built up, and the 2 degrees of freedom (2-DOF) approach has been taken to achieve efficient torque control performance. The model of the cable-driven SEA system was built up by taking the motor as a PI-controlled velocity source. Then, the stabilizing 2-DOF controllers are parameterized. This control strategy provides a solution for separately pursuing the goals of reference tracking and robustness. Based on this, the torque controller can be designed to achieve the optimal performance tuned by three parameters. The simulations have validated the efficiency of the 2-DOF torque control method for the cable-driven SEA.