Global practical tracking via adaptive output-feedback for uncertain nonlinear systems with generalized control coefficients

Abstract

This paper investigates the global practical tracking via adaptive output-feedback for a class of uncertain nonlinear systems with generalized control coefficients. Notably, the system in question has the function-of-output control coefficients and the serious unknowns in the system and the reference signal, and hence is essentially different from the existing closely related literature. To solve the global practical tracking, a high-gain observer is first introduced to reconstruct the unmeasurable system states, and then an adaptive output-feedback controller is designed. It is worth emphasizing that the gains in the designed observer and controller are functions of time and output, for which a novel updating law of the high-gain is introduced to overcome the additional system nonlinearities and the serious unknowns mentioned above. The designed controller is shown such that all the states of the closed-loop system are globally bounded, and furthermore, tracking error will be ultimately prescribed sufficiently small. A numerical simulation is provided to demonstrate the effectiveness of the proposed approach.

创新点

本文研究了一类带有泛化控制系数不确定非线性系统的自适应输出反馈实际跟踪。与已有相关文献不同,所研究系统的控制系数是输出的函数,且系统非线性和跟踪信号中有严重未知性。为解决该问题,引入了一个高增益观测器来重构系统的不可测状态,进而设计了一个自适应输出反馈控制器。需强调的是,观测器和控制器中的高增益是输出和时间的函数,其新型调节律克服了提到的未知性及函数控制系数导致的额外系统非线性。所设计的控制器确保了闭环系统状态的全局有界性和跟踪误差最终为(事先给定的)充分小。