Saturation Functions Based Control for Series Elastic Actuator with Feedback Linearization

In this paper, a saturation functions based control law with feedback linearization (FL) is proposed for the trajectory tracking control of a series elastic actuator (SEA) system. A feedback-based stabilisation-bounded control action shaped by saturation functions is designed. The controller consists of two parts, one is a feedforward controller which guarantees high order tracking errors converge to a small region, the other is a feedback controller which brings the entire state errors of the SEA system asymptotically converge to zero. In the second part of controller, the saturation function is not unique. Closed-loop stability is established by the Lyapunov method and LaSalle’s invariance principle. The effectiveness of the proposed control strategy is verified by simulations and experiments based on a SEA-driven robot arm.