Research On Output Feedback Control Of Several Types Of Nonlinear Systems

Output feedback control of nonlinear systems has always been a hot issue in the field of control theory research.Output feedback stability is a prerequisite to consider other control issues such as tracking issues,interference suppression issues,etc.In addition,in most actual physical systems,the output feedback control is more practical because of the unmeasurable of the state.This paper considers the design and analysis of output feedback controller for a class of nonlinear systems.The main contributions include:Chapter 1 studies the problem of global output feedback stabilization for a class of nonlinear time-delay systems with unknown output function.The main contribution in this section is to extend the linear output function in the existing literature to the general unknown output function,and to extend the ratio of high-order growth conditions in the nonlinear term to arbitrary non-negative real numbers.Due to the existence of unknown output functions and time-delay terms,by constructing the appropriate Lyapunov-Krasovskii functional and observer,skillfully combining generalised adding a power integrator technique,sign function and homogeneous domination approach,an output feedback controller is designed to guarantee globally uniformly asymptotical stability of nonlinear time-delay systems with the unknown output function.Chapter 2 considers a class of uncertain nonlinear feedforward systems with unknown constant growth rate,output polynomial function growth rate and system input function growth rate.Under the most general growth rates condition,only one dynamic gain is designed to compensate simultaneously these three types of growth rates.We optimized the results of using two dynamic gains to compensate the unknown constant growth rate and the function growth rate,respectively,and reduced the dynamic order of the closedloop system.An output feedback controller is constructed to guarantee the boundedness of closed-loop system states and the convergence of original system states.Then we generalize this design idea of dynamic gain to a class of uncertain feedforward systems with disturbances.The corresponding output feedback control results are also obtained,indicating the effectiveness of the dynamic gain design form.Chapter 3 gives summary and outlook of the thesis.