Research On Control Problems Of High Order Nonlinear Systems With Time-delay And Unmodeled Dynamics

Nonlinear, time-delay, dynamic and parametric uncertainties are commonly encountered in real systems, and the existence of time-delay is often a significant cause of instability and oscillation, dynamic and parametric uncertainties often arises from many different control engineering applications. Hence, the study of time-delay nonlinear systems and nonlinear systems with dynamic and parametric uncertainties has received much attention. In this paper, for nonlinear systems with time-delay and nonlinear systems with dynamic and para-metric uncertainties, the problems of controller design and stability analysis are investigated. The main contributions include:Chapter 1 studies the global stabilization problem for a class of high-order nonlinear sys-tems with time-delay. At the assumed condition of both lower and high-order nonlinearities included in the studied systems, by constructing the new Lyapunov-Krasovskii functional and the reduced-order observer, based on homogeneous domination theory together with the adding a power integrator method, an output feedback controller is developed to guarantee the equilibrium of the closed system globally uniformly asymptotically stable.Chapter 2 studies global adaptive finite-time stabilization of a class of high-order nonlin-ear systems with dynamic and parametric uncertainties. By skillfully combining Lyapunov function, sign function, and finite-time input-to-state stability approaches, an adaptive state feedback controller is designed to guarantee high-order nonlinear systems globally finite-time stable.Chapter 3 gives summary and outlook of the thesis.