Study On Output-Feedback Stabilizing Control For Nonlinear Systems With Multiple Uncertainties

Feedback control of nonlinear systems is widely used in robot control,power system,aircraft manufacture and so on.Under the different assumptions,this paper solves the corresponding problem of output-feedback adaptive stabilizing control for a class of nonlinear systems with multiple uncertainties by using the idea of universal control and the method of backstepping.The main content of this paper is divided into the following four parts: The first three parts are studied under the condition that the growth of nonlinearities depends on unmeasured states,and the growth rate is the form of an unknown constant multiplying polynomial-of-output.Part 4 is the application of Part 1.1)Design of output-feedback stabilizing control for planar nonlinear systems with unknown measurement sensitivity but known upper and lower boundsChapter 2 investigates the problem of adaptive stabilization via output-feedback for a class of uncertain planar nonlinear systems in the presence of uncertainty in both state and output equations.We propose a non-identifier based output-feedback control scheme.The observer gains are composed of two components,and both of them are dynamically updated in the new forms.The designed controller based on a high-gain observer can ensure that all the signals of the closed-loop system are globally bounded and the states of the original system and the observer converge to zero.An example is given to illustrate the effectiveness of the proposed method.2)Design of output-feedback stabilizing control for general nonlinear systems with unknown measurement sensitivity but known upper and lower boundsChapter 3 extends the planar nonlinear systems to general nonlinear systems on the basis of Chapter 2,and achieves the output-feedback adaptive stabilization of general nonlinear systems.Similar to Chapter 2,we introduce an observer with two dynamic gains,and the two high-gains need to be dynamically updated in the new form.We propose a non-identifier based output-feedback smooth control scheme.The designed controller can ensure that all signals of the closed-loop system are globally bounded and the states of both the original system and the observer converge to zero.A simulation example is used to demonstrate the effectiveness of the proposed method.3)Design of output-feedback stabilizing control for planar nonlinear systems with unknown control coefficient but only known lower boundChapter 4 relaxes the assumption on the control coefficient/measurement sensitivity,and studies the problem of output-feedback adaptive stabilization for a class of planar nonlinear systems with an unknown control coefficient but known lower bound.A non-identifier based output-feedback smooth control scheme is proposed.The designed controller based on an observer with two dynamic high-gains and an appropriate update law can realize that all signals of the closed-loop systems are globally bounded and the states of the system and the observer converge to zero.The efficiency of the proposed method is demonstrated by a practical example.4)Design of output-feedback stabilizing control for a class of single-link robot nonlinear systemsAs an application of Chapter 2,the problem of output-feedback adaptive stabilization for a class of single-link robot systems with unknown system parameters but known upper and lower bounds of inertia is studied in Chapter 5.To solve this problem,the controller based on a high-gain observer is constructed,which guarantees that the global adaptive stabilization of the single-link robot system is achieved.Simulation results show the effectiveness of the proposed method.