Adaptive Switching Control Of Uncertain Nonlinear Systems

During the last four decades,the control problem of uncertain nonlinear systems has been one of the hot topics of intensive interest in the field of nonlinear control.Particularly,adaptive control of nonlinear systems with unknown control directions has attracted more and more attention from international scholars and a lot of meaningful results have been obtained.However,in practical application,there are many worthwhile questions to make a further discussion and study.This thesis mainly studies the stability and event-triggered control problem of uncertain nonlinear systems.Moreover,the exponential stability of Camassa-Holm equation has been solved by the approach of event-triggered control.Details are listed as follows:1.In Chapter 3,the globally generalized exponentially stable adaptive switching control problem a class of nonlinear systems with unknown control directions is investigated.A switched function depended on the state of systems is introduced to each step of the Backstepping design process.A Lyapunov-based adaptive switching controller is designed by constructing such a new switched function.It is show that the proposed controller can guarantee the global generalised exponential stability of closed-loop systems.The main advantage of the proposed controller is divided to two parts: one convectional adaptive control law is used to obtain the stability of system,another one adaptive logic switched law is proposed to deal with the unknown control directions.Such a particular controller structure will be applied in dealing with the systems with unknown direction.2.In Chapter 4,on the basis of the above theory research and results,the designed method of the third chapter is applied to a class of ship course-keeping system.The ship-keeping control problem for the ship's course is required to achieve desired ship's course at a certain speed or in a finite time are addressed.In order to solve this problem,a new Lyapunov-based adaptive switching controller is obtained by combining the adaptive Backstepping technique and logic switching law.The designed controller is not only guarantee the exponential stable,but also ensure the finite-time stable.3.In Chapter 5,the event-triggered control scheme is applied to a class of nonlinear systems with multiple unknown control directions.Firstly,an adaptive switching approach is proposed to deal with the unknown control direction of the closed-loop systems.Then,two kinds of switched control that includes the adaptive switching control and the eventtriggered switching control are introduced to such a systems.Meanwhile,the globally generalized exponentially stable is decided whether the switching event and the triggering event are switched or not.Under two kinds of switched control,the global generalised exponential stability of the closed-loop system is guaranteed by the adaptive logic switching law and the event-triggered switching law.4.In Chapter 6,the event-triggered control scheme proposed in Chapter 5 is extended to infinite dimensional systems.We addressed the event-triggered control problem of a class of viscous Camassa-Holm equation.Under the initial condition and boundary condition,the exponential stability of the Camassa-Holm equation is ensured by the proposed control scheme.