Adaptive super-twisting nonsingular fast terminal sliding mode control for cable-driven manipulators using time-delay estimation

Abstract

To guarantee high-precision trajectory tracking control of cable-driven manipulators under complicated unknown uncertainties, we propose a novel adaptive super-twisting nonsingular fast terminal sliding mode (AST-NFTSM) control scheme using time-delay estimation (TDE) in this paper. The proposed TDE-based AST-NFTSM control scheme mainly contains three terms: a TDE term used to estimate and compensate the remaining lumped system dynamics; an AST term applied to ensure fast convergence and strong robustness in the reaching phase; and a NFTSM term utilized to guarantee fast convergence and high precision in the sliding mode phase. Thanks to the TDE scheme, no system dynamics are required and a fascinating model-free feature is achieved. In the meantime, fast convergence and high precision and strong robustness can be effectively ensured using the AST and NFTSM terms. The stability of the closed-loop control system is analyzed using Lyapunov method. Finally, the validity and superiorities of our newly proposed TDE-based AST-NFTSM control scheme were demonstrated through comparative 2-DOFs (degree of freedoms) simulation and experiments.