Terminal sliding mode disturbance observer based adaptive super twisting sliding mode controller design for a class of nonlinear systems

Abstract

In this paper, an adaptive super twisting sliding mode controller (ASTSMC) is proposed for a class of nonlinear systems to counteract mismatched uncertainties. To estimate the unknown external disturbance efficiently, an adaptive terminal sliding mode disturbance observer (ATSMDO) is proposed. The stability of the over all closed loop system is proved by Lyapunov stability theory. To validate the proposed ATSMDO based ASTSMC, a case study of a nonlinear liquid level regulation problem is considered. Both simulation and real-time results are presented to show the effectiveness of the proposed controller than the traditional adaptive sliding mode controller (ASMC) and reported controllers in literature. From the analysis, it is observed that the proposed controller alleviates the chattering problem effectively.