Sliding Mode-Based Design of Unified Force and Position Control for Series Elastic Actuator

This paper presents unified force and position control based on sliding mode control (SMC) for a series elastic actuator (SEA). Compliant motion of robotic systems is crucial when dealing with unstructured environments as in the case of physical human-robot interaction. Therefore, not only traditional mechanical systems with stiff joints but also mechanically compliant systems such as SEAs have been actively studied. In order to accomplish versatile tasks, the strategy enabling both position control and force control is favorable. In this paper, the controller synthesizing position and force controllers on the basis of SMC for the control problem of SEAs is proposed by extending our previous work. Simulation results demonstrate the feasibility of the proposed method.