Adaptive Sliding Mode Control for Series Elastic Actuator Robots

Series elastic actuator (SEA) robots have garnered significant interest in the field of industry, particularly in rehabilitation, due to their safe human-robot interaction. Nevertheless, controlling a SEA robot system poses challenges arising from the underactuated nature of the system caused by the presence of elastic elements, as well as the presence of mismatched uncertainties that compromise the performance of the applied controller. To resolve these issues, an adaptive hierarchical sliding mode control design is proposed for a one-degree-of-freedom (DoF) SEA robot system. The global sliding surface is designed to satisfy the Lyapunov stability theorem. Meanwhile, adaptive law can be derived based on the Lyapunov–like design. Simulation results demonstrate that the proposed control strategy yields satisfactory tracking performance, system stability, and vibration suppression.