Adaptive fuzzy dynamic surface control for unknown time delay nonlinear systems preceded by unknown asymmetric hysteresis

Abstract

In this paper, a fuzzy approximator based adaptive dynamic surface control scheme is proposed for a class of unknown time delay nonlinear systems preceded by asymmetric hysteresis nonlinearities. The features of the proposed method are: 1) by combining the approximated property of the fuzzy logic systems (FLSs) with the Finite Covering Lemma, the Krasovskii functionals are disposed of, achieving the ℒ ∞ norm of the tracking error by using the initializing technique; 2) the assumptions on the time-delay functions are removed due to the use of the Finite Covering Lemma and the FLSs; 3) the proposed adaptive fuzzy dynamic surface control scheme can also compensate the asymmetric shifted Prandtl Ishlinskii (ASPI) hysteresis without constructing the inverse of the ASPI model with the density function of ASPI model being unknown and estimated on-line to compensate the hysteresis. It is proved that all the signals in the closed-loop system are ultimately uniformly bounded and can be made arbitrarily small. Simulation results show the validity of the proposed method.