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Two Types Of Complex Systems, Adaptive Control Problem

Posted on:2011-06-09Degree:MasterType:Thesis
Country:ChinaCandidate:R J DongFull Text:PDF
GTID:2208360305468636Subject:Operational Research and Cybernetics
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This paper mainly deals with two kinds of adaptive control problem,which is divided into the following two parts.1. The robust output feedback control problem for a class of nonlinear systems with iISS unmodeled dynamics.In this part, we consider the problem of output feedback tracking problem with dynamic uncertain systems. Recently, many research show that iISS is strictly weaker than ISS. It presents a class of much more general nonlinear systems. The uncertain dynamics subsystem of it satisfies integral input-to-state stability. In order to deal with unmodeled state, we apply the method of changing supply function to overcome the difficulties of dynamic uncertainties. In view of the unknown state, it cannot be applied in the feedback design. Based on the structure of the system, we construct a dynamic observer. And then with Backstepping method, we design an output feedback controller to achieve the global asymptotic tracking to arbitrary constant of internal state and output. The tuning function design is also applied which effectively avoids overparameterizatin.2. The design and analysis of the direct model reference adaptive control with relative degree four stable control.In this part, we use the method of Kp= SDU to enlarge n*= 2 to n*= 4. To the system with relative degree four,there are some difficulties. If we imitate the control law of the system with relative degree two,which involvesθandθ,which is not available for measurement. Consequently the control law cannot be implemented and the choice of control law is not feasible. To the system with relative degree four,we introduce nonlinear damping two times based on stability considerations. By designing nonlinear damping, a closed-loop system is obtained, based on the system,a design scheme of adaptive output feedback controller is given. A simulation is given to show the effectiveness of the proposed scheme.
Keywords/Search Tags:input-to-state stability, integral input-to-state stability, output feedback, relative degree, model reference adaptive control, estimation error, nonlinear damping
PDF Full Text Request
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