Adaptive Fuzzy Output-Feedback Control for Nonaffine MIMO Nonlinear Systems With Prescribed Performance

Abstract

This article proposes an adaptive fuzzy output-feedback control approach for a class of nonaffine multi-input multi-output nonlinear systems with prescribed performance and immeasurable states. For most of the existing fuzzy approximation-based approaches, there are many parameters in the fuzzy systems that need to be estimated online with adaptive laws. To overcome this difficulty, we propose a new fuzzy system; the remarkable advantage of this fuzzy system is that only one parameter needs to be estimated online. The fuzzy system is used to approximate the unknown nonlinear function, and an adaptive fuzzy state observer is developed to estimate the unmeasured states. By utilizing the state observer and the prescribed performance control scheme, an adaptive fuzzy prescribed performance output-feedback control method is developed. The number of the adaptive laws both for the state observer and the controller is reduced to the number of subsystems. It is proved that all the signals in the closed-loop systems are semiglobally uniformly ultimately bounded, and that the prescribed performance error constraints can be achieved. Simulation examples are provided to highlight the effectiveness of the proposed approach.