Observer-based continuous adaptive sliding mode control for soft actuators

Fabricated by high elastic materials, soft actuators provide a prominent solution for soft rehabilitation gloves, soft graspers and locomotion robots. However, the control of soft actuators is a grant challenge due to dynamic modeling error and unavailable system states. This paper proposes an observer-based continuous adaptive sliding mode controller for soft actuators in the presence of system uncertainties without knowledge of its upper bound in prior. By exploiting a novel nonsingular fast terminal sliding mode (NFTSM) surface and a high-order sliding mode (HOSM) observer, the proposed control scheme features adaptive-tuning gains, continuity, singularity-free, stronger robustness and higher tracking accuracy. The stability of the proposed controller is analyzed by the Lyapunov method. Corresponding comparative simulations and experiments of a soft pneumatic network actuator verify the effectiveness and related features of the proposed controller.