标题：Global practical tracking for nonlinear systems with unknown relative degree
作者：Wang, Meiqiao ;Liu, Yungang ;Man, Yongchao
作者机构：[Wang, Meiqiao ;Liu, Yungang ;Man, Yongchao ] School of Control Science and Engineering, Shandong University, Jinan; 250061, China
会议名称：2017 Chinese Automation Congress, CAC 2017
会议日期：20 October 2017 through 22 October 2017
来源：Proceedings - 2017 Chinese Automation Congress, CAC 2017
关键词：global practical tracking; non-parametric uncertain nonlinearities; Nonlinear systems; switching logic; unknown control direction; unknown relative degree
摘要：This paper considers global practical tracking for a class of nonlinear systems with unknown relative degree, unknown control direction and non-parametric uncertain nonlinearities. Different from the existing results, known upper bound is not required for the unknown relative degree, which makes it impossible to design a filter with fixed dimension. To compensate the multiple uncertainties, a novel strategy is proposed based on switching mechanism to construct a dynamic output-feedback controller with a varying-dimensional filter, whose gain and dimension are tuned online via a switching logic. It is rigorously shown that the switching type output-feedback controller can guarantee that the system error reaches prescribed small accuracy before a pre-specified time, with pre-specified maximum overshoot, and the system state is globally bounded. © 2017 IEEE.