Model‐free finite‐time terminal sliding mode control with a novel adaptive sliding mode observer of uncertain robot systems

Abstract

AbstractThis paper presents a model‐free finite‐time terminal sliding mode control scheme of uncertain robot systems. Time delay estimation (TDE) technique is employed to estimate mathematical model of system. However, TDE cannot achieve satisfactory performance when the system suffers from impactive disturbances. For this reason, a novel adaptive sliding mode observer is designed to compensate estimation errors. Moreover, the proposed observer is finite‐time stable and the design process does not depend on the upper bounds of uncertainties and its derivatives, and it can be also extended to other nonlinear systems with external disturbance. A nonsingular fast terminal sliding surface is designed to accelerate convergence rate and boundary layer technique is adopted to attenuate the chattering phenomenon. Finally, a finite‐time stable controller is constructed to stabilize the closed‐loop system. The proposed controller is model‐free and can be easily implemented in practice. The stability of both observer and controller is strictly proven in the Lyapunov framework. Simulations and experimental studies using Rethink Sawyer Robot are carried out to verify the effectiveness of the proposed scheme.