Output-Feedback Control Design For Switched Nonlinear Time-delay Systems

Switched systems consist of a family of dynamical subsystems and a switching signal governing the switching among them.They have become an important branch in the field of control.Due to the interaction among their dynamics,time-delay,and switching rules,switched time-delay systems may become very complicated than time-delay systems or switched systems.The operation mechanism of switched time-delay systems is far from clear or less well understood,and the analysis and design of the systems need to be solved urgently.Meanwhile,since the states of the practical system are immeasurable,the study of the output feedback control of switched nonlinear time-delay systems deserves investigation for great theoretical development as well as for practical applications.Therefore,compared with the existing literature on switched nonlinear time-delay systems,this dissertation devotes on the constructive design method of output feedback control of switched nonlinear time-delay systems by exploiting switched system theory,average dwell time method,Lyapunov-Razumikhin theorem and multiple Lyapunov-Krasovskii functionals.The main results of this thesis are summarized as follows:(1)The problem of semi-global output-feedback stabilization is addressed for a class of switched nonlinear time-delay systems in strict-feedback form.A switched state observer is first constructed,then switched linear output-feedback controllers for individual subsystems are designed.By skillfully constructing multiple Lyapunov-Krasovskii functionals and successfully solving several troublesome obstacles,such as time-varying delay and switching signals and nonlinearity in the design procedure,the switched linear output-feedback controllers designed can render the resulting closed-loop switched system semi-globally stabilizable under a class of switching signals with average dwell time.Furthermore,under some milder conditions on nonlinearities,the semi-global output-feedback stabilization problem for switched nonlinear time-delay systems is also studied.Simulation studies on two examples,which include a continuous stirred tank reactor,are carried out to demonstrate the effectiveness of the proposed approach.(2)The problem of global stabilization is investigated for a class of switched feedforward nonlinear time-delay systems in which time delays appear in both states and input.Also,the switching signal of candidate controllers of subsystems exists time delays,which makes the switching between the subsystems and the controllers asynchronous.An effective constructive method is provided to design switched dynamic state-feedback controllers and switched dynamic output-feedback controllers,respectively.Design difficulties from time delays and asynchronous switching and nonlinearity are overcome using the Lyapunov-Razumikhin theorem and the multiple Lyapunov-Krasovskii functionals method.Some sufficient conditions for global exponential stability of switched feedforward nonlinear time-delay systems under asynchronous switching incorporated with a time-varying average dwell time are given.Simulation studies on two numerical examples,which include a practical switched induction heater circuit system,are carried out to demonstrate the effectiveness of the proposed approach.The conclusions and perspectives are presented at the end of the thesis.