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Robust Control For Continuous Uncertain Time-delay Systems

Posted on:2002-06-17Degree:MasterType:Thesis
Country:ChinaCandidate:X Y LuoFull Text:PDF
GTID:2168360032951740Subject:Control theory and control engineering
Abstract/Summary:PDF Full Text Request
Time-delay systems exist widely in real world. It has been indicated that the time delay can destroy the stability of system and degrade the control performance. With the increasing of the complexity of the control systems and the control performance, the study for time-delay systems, as a specialist research area, has been a historical and challengeable subject. The uncertainty of the system describes the difference between the mathematic model and controlled plant, which reflects the existing of the variation of the system parameters and disturbance. In a word, it is of a great importance in theoretical and practical application to study the robust control for the uncertain time-delay systems. In this thesis, the problem of robust stability analysis and robust control for different continuous uncertain time-delay systems. According to the relationship between the controller design and the size of delay, we use robust delay-independent and delay-dependent control. At the same time, the problem of robust guaranteed cost H~ control with given attenuance. Furthermore, we make deep research for neutral delay-differential systems. Deep investigations on some delay-independent robust stability and delay-independent stabilization problems for several classes of time-delay systems, are considered, respectively. The main results are: 1) analyzes the problems of robust asymptotic stability and robust exponential stability for open-loop systems with multiple time delays based on Lyapunov equation approach, respectively. Moreover, investigates robust control problems based on Riccati equation approach; 2) proposes an augment Riccati equation approach to solve the robust ~ control problem of uncertain time-delay systems. The blindness in solving general Riccati equations is overcome; 3) discusses the problem of robust H~ control for general uncertain systems with multiple time delays and obtains LMI-based sufficient conditions satisf~iing H~ performance. All the above results extend and develop the existing work. For a class of uncertain time-delay systems with nonlinear perturbations, the problems of delay-dependent robust stability and stabilization are investigated, respectively. At first, we analyzed the problems of delay-dependent robust asymptotic stability and exponential stability for open-loop systems by applying Lyapunov-Krasovskii functional methods, then we discuss robust control for such systems via memoryless state feedback. Furthermore, for the case that not all the states can be measured, the delay-dependent problem is presented via static output feedback and the problem of delay-dependent H~, control is discussed by observer-based state feedback, respectively. All results are given in terms of LMIs. Because these LMIs depend on the size of time delay, they have little conservative. And we give some novel exponentially stable conditions. The problem of robust control with multiple performance index is considered. Based on the definition of robust guaranteed cost ~ control with a stability, a new LMJ condition which satisfies the given definition is obtained via memoryless state feedback by transforming the system state and filtering output perturbations firstly. Then, we obtain the sufficient conditions guaranteeing cx stabilization with guaranteed cost H~ performance via observer-based state feedback. The potential efficiency of the methods is demonstrated by numerical examples and simulations. By introducing a special Lyapunov-Krav...
Keywords/Search Tags:uncertainty, time delay, robust stability, exponent stability, robust H_∞ control, robust guaranteed cost control, observer, neutral delay system
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