Fuzzy Supertwisting Dynamic Surface Control for MIMO Strict-Feedback Nonlinear Dynamic Systems With Supertwisting Nonlinear Disturbance Observer and a New Partial Tracking Error Constraint

Abstract

This paper proposes a hybrid fuzzy dynamic surface control (DSC) method combined with a supertwisting control (STC) method and a supertwisting nonlinear disturbance observer (STO) for multi-input multi-output nonlinear strict-feedback systems is proposed, in addition to a new partial tracking error constraining method. For the design of the stabilizing controls of the DSC, the virtual tracking errors in recursive procedures were transformed into the design variables of the STC. The uncertainties were estimated by an STO, which includes the approximation error between the unknown plant dynamics and fuzzy optimization function, in addition to the external disturbances. Furthermore, the proposed DSC combined with the STC scheme can prevent the complex analysis problem of the filtered output error in conventional DSC schemes. Moreover, a novel convenient tracking error constraining method is also presented. Simulation results revealed that the proposed scheme has an improved tracking error performance and robustness to uncertainty than control systems with a conventional nonlinear disturbance observer and several other DSC schemes.