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Robust Adaptive Control For Uncertain Switched Systems Under Arbitrary And Restricted Switching

Posted on:2016-12-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:C Y WangFull Text:PDF
GTID:1108330479950980Subject:Control Science and Engineering
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Switched systems have broad applications in various engineering fields, such as chemical processes, aerospace and hydraulic servo, etc. The dynamic properties of the switched systems become excessively intricate due to the existence of the switching. The switching makes the dynamic properties of systems no longer be a simple superposition of performance of each subsystem, and sometimes may leads to totally opposite performance. As such, enormous challenges lay ahead for the control research about the switched systems. With the continuous emergence of complex and large scale systems, various control problems urgently need to be solved for switched systems, and control methods need to be further improved and enhanced.This paper focuses on specific design problem about the common controller under arbitrary switching and the synchronous and asynchronous switched controller under certain restricted switching, respectively. The main contributions in this thesis are as follows:Firstly, under arbitrary switching signals, robust stabilization, adaptive stabilization and adaptive tracking control problems are studied for the uncertain switched systems.Based on common Lyapunov functional method, a systematic recursive algorithm for designing a common smooth feedback controller is proposed on the robust stabilization problem for a class of uncertain switched nonlinear systems. The common controller designed explicitly can guarantee the resulting closed-loop switched system to be robust globally asymptotically stable at the equilibrium under arbitrary switching. Furthermore, robust stabilization problem is studied under arbitrary switching for a class of cascade nonlinear switched systems. An illustrative example is presented to show the efficiency of the given recursive approach.Based on common Lyapunov functional method, the adaptive stabilization problem for a class of nonlinearly parameterized switched systems is discussed. A common smooth adaptive controller and adaptive law independent of switching signals are presented by a systematic recursive design method. Under arbitrary switching, the given controller can guarantee the Lyapunov stability at the equilibrium of the resulting closed-loop switched system and the convergence of the original switched system states. Meanwhile, the developed design method can be extended to adaptive arbitrarily switching stabilization problem for a class of cascade switched nonlinear systems. The efficiency and feasibility of the developed method are demonstrated by a numerical example and a physical system.The adaptive tracking control problem for a class of nonlinear switched systems with unavailable states is studied. By designing a proper reduced-order observer and introducing fuzzy approximation, a systematic adaptive recursive control method is presented to explicitly construct a common smooth adaptive output feedback controller. As such, all error variables of the corresponding closed-loop switched systems are semi-globally, uniformly, and ultimately bounded under arbitrary switching. Also the tracking error may be adjusted to a small neighborhood of the origin. The efficiency and feasibility of the proposed method are demonstrated by both a numerical example and a chemical system.Secondly, the adaptive synchronous control and the robust asynchronous control problems are studied for the uncertain switched systems.The adaptive synchronous control problem is studied for a class of switched nonlinear systems. Based on multiple Lyapunov functions and Backstepping technique, the specific design methods are presented for the switching controllers and the state-dependent switching signals according to the minimum-energy switching rules. As such, the corresponding closed-loop switched systems are Lyapunov stable. Moreover, combining with the average dwell time method, the synchronous tracking control problem is studied for a class of MIMO nonlinear switched systems. The design process of the adaptive controller and the time-dependent switching laws are given to guarantee the corresponding closed-loop switched systems to be uniformly and ultimately bounded. Simulation results validate the efficiency of the proposed method.Combining with multiple Lyapunov functions technique and mode-dependent average dwell time method, the robust asynchronous switching control problems are studied for a class of uncertain delay switched systems with unavailable states. Some sufficient conditions are presented to construct the observer-based asynchronous output feedback controller and the time-dependent switching law. As such, the robust attenuation performance is insured for the corresponding closed-loop switched systems. Numerical simulation validates the effectiveness of the proposed method.
Keywords/Search Tags:switched systems, robust control, adaptive control, arbitrary switching, restricted switchings, asynchonous switching, Backstepping design, mode-dependent average dwell time
PDF Full Text Request
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