Output-feedback control of uncertain nonlinear systems using a self-structuring adaptive fuzzy observer

This paper describes the design of an output-feedback controller based on an adaptive fuzzy observer for uncertain single-input, single-output nonlinear dynamical systems. We have focused on the realization of a minimal dynamic order for the adaptive fuzzy observer. For this purpose, we adopt an adaptive fuzzy observer in which no strictly positive real (SPR) condition is needed and we combine a self-structuring scheme with an on-line estimation of fuzzy parameters. By using this proposed scheme, we can reduce the dynamic order of the adaptive output-feedback fuzzy control system. The Lyapunov synthesis approach is used to guarantee a global uniform ultimate boundedness property of the state estimation error and tracking error, as well as all other signals in the closed-loop system. No a priori knowledge of an upper limits on the uncertainties including optimal parameters and modeling errors is required. The theoretical results are illustrated through simulation examples. (C) 2004 Elsevier B.V. All rights reserved.