Composite Nonlinear Feedback Control For Some Classes Of Nonlinear Systems

Composite nonlinear feedback control(CNF)is a control system design method for solving the tracking control problem of control systems with input constraint.The goal of the composite nonlinear feedback control method is to solve the tracking problem while the transient performance of the closed-loop system is improved,namely the fast response of the closed-loop system is achieved while the overshoot is suppressed.Cur-rently,the composite nonlinear feedback control method is developed mainly for linear systems with input constraint,whereas,for nonlinear systems and multi-agent systems,it has not been fully developed.In view of this,this dissertation extends the framework of composite nonlinear feedback control technique to some classes of nonlinear sys-tems and multi-agent systems.Three issues are focused in this dissertation,as follows:I.Composite nonlinear feedback control for strict-feedback nonlinear systems with input constraint.Firstly,without considering the input constraint,the backstep-ping based stabilizable controller is designed for strict-feedback nonlinear systems by standard backstepping control technique.Secondly,the feedforward compensation of the reference signal is calculated based on the given step reference signal and the param-eters of the backstepping based stabilizable controller,then the feedforward compensa-tion is added to the backstepping based stabilizable controller to form the backstepping based tracking controller.By choosing the parameters of the backstepping based sta-bilizable controller,the output of the system can track the given reference step signal rapidly,whereas,it may cause large overshoot.Finally,to suppress the overshoot gener-ated by the backstepping based tracking controller,the nonlinear feedback performance compensator is designed and added to the backstepping based tracking controller to for-m the composite nonlinear feedback control law.It has been proved that the nonlinear feedback performance compensator will not break the steady state performance of the backstepping based tracking controller.Simulation results show that the composite nonlinear feedback controller can improve the transient performance of the closed-loop system effectively.II.Composite nonlinear feedback control design for a class of single-input single-output nonlinear systems with input constraint.Firstly,without considering the input constraint,the state feedback tracking controller is designed through the input-output linearization technique,so that the output of the system can track the time-varying ref-erence signal rapidly.Secondly,in order to suppress the overshoot generated by the tracking control law,a nonlinear feedback performance compensator is designed and added to the tracking control law to form the composite nonlinear feedback controller,the added nonlinear feedback performance compensator of the composite nonlinear feedback controller will not affect the steady state performance of the closed-loop sys-tem.Simulation results show that the nonlinear feedback performance compensator can improve the transient performance of the closed-loop system effectively.?.Composite nonlinear feedback control design for multiagent systems with in-put constraint.Firstly,without considering the input constraint,the distributed tracking controller is designed to drive the system to track the given time-varying reference signal rapidly.Secondly,to suppress the overshoot generated by the distributed track-ing control law,a nonlinear feedback performance compensator is designed and added to the tracking control law to form the composite nonlinear feedback controller.It has been proved that the added nonlinear feedback performance compensator will not break the stability of the closed-loop system.Simulation results show that the added nonlinear feedback performance compensator can reduce the overshoot caused by the tracking controller,it means that the transient performance of the closed-loop system is improved by the composite nonlinear feedback controller.