Robust Adaptive Dynamic Surface Control of Nonlinear Time-varying Systems in Strict-feedback Form

Abstract

In this paper, the problem of robust adaptive control for nonlinear systems with unknown time-varying parameters and disturbance is considered. For this purpose, an indirect adaptive controller based on the Dynamic Surface Control (DSC) is proposed where an adaptive scheme is presented to provide estimations of unknown time-varying parameters. First, the parameters are approximated in terms of polynomials with unknown coefficients using the Taylor series expansion. Then, these unknown coefficients are estimated using a novel adaptive law. It is shown that the proposed control scheme guarantees the stability of the overall system and the tracking error can converge to a desired small residual. Finally, simulation results are given to demonstrate the effectiveness of the proposed method.