Robust H_âˆž Control For Uncertain TimeDelay Systems And Its Application In Networks' Congestion Control  Posted on:20040501  Degree:Master  Type:Thesis  Country:China  Candidate:N J Su  Full Text:PDF  GTID:2168360092475623  Subject:Control theory and control engineering  Abstract/Summary:  PDF Full Text Request  It is always impossible to obtain accurate mathematics model for the practical industrial processes. The model under which the controller is designed is usually different to the real plant owing to model reduction, linearity approximations and the ignoring of the dynamics difficulty for modeling, the changing of the operating environment and other unmeasurable disturbances. These differences usually can be described as the uncertainties in the model arguments. Robust control, the control design method considering such uncertainties when designing controller is a effective way to deal with the uncertain parameters. On the other hand, because of transmission process, largelag links and complicated online analyzer etc, a large number of industrial processes (in metal engineering, chemical engineering systems, biomedical systems and so on) can be modeled as timedelay systems. The stability and performance are always dominated by delay phenomena, so the study of delay systems always attracts considerable attention in the control theory literature.In this paper, kinds of robust stabilization and robust H control problems forlinear uncertain timedelay systems are studied in detail. As to the frequency domain methods, the physical significations of the H performance targets, the selectionstrategy of the weighting functions, loopshaping and standard problems of robust H control are discussed. Frequency domain design methods of robust H controlare also introduced to solve the congestion control problem of the highspeed communication networks, which based on flow rate control. On the other hand, as to the time domain methods, based on LyapunovKrasovskii function method, Riccati equation method, linear matrix inequality technique, along with the skills of equality and inequality transformations, the robust stabilization and robust H controlproblems are studied via state feedback for some kinds of uncertain timedelay systems, and delayindependent as well as delaydependent results are obtained. The main contents of this paper are outlined as follows,(1) The physical significations and the correlativities of the oftenused Hperformance targets are summarized, the selection strategies of the weighting functions are researched, and loopshaping method as well as standard problems of robust H control are introduced. The frequency domain methods of robust Hcontrol are also introduced to solve the ratebased congestion control problem of thehighspeed communication networks, and the H based controller are designed todeal with the timedelay problem of the single bottleneck node and multiple resources networks.(2) For linear systems with timevarying delays both in state and control, and subject to normbounded parameter uncertainties, the problems of robust stabilization and robust H control are studied and delay independent results are derived byconstructing proper Lyapunov function to deal with the timedelay, also by using Riccati equations method and inequalities transformations to deal with the uncertainties. According to the transform function of the system, frequency domain method and time domain method are combined together to analyze the robust Hcontrol problem of the uncertain timedelay system.(3) A new design approach of delaydependent robust stabilization and robust Hx controller for a class of uncertain timedelay systems is provided. The sufficient conditions of delaydependent robust stabilization and robust H control, which are simpler, less conservative and can be used to deal with not only small delay systems but also large delay systems, are derived based on a new state transformation and given in terms of linear matrix inequalities (LMIs).(4) For a class of uncertain timedelay systems with multiplestate delays, new delaydependent robust stabilizability and robust H Control criteria are derivedbased on LyapunovKrasovskii functional method and given in terms of linear matrix inequalities (LMIs), which are proved by the numerical examples to be...
 Keywords/Search Tags:  timedelay, uncertainty, continuous, linear, robust control, robust stabilization, robust H_âˆž control, state feedback, delayindependent, delaydependent, H_âˆž performance targets, weighting functions, loopshaping, congestion control  PDF Full Text Request  Related items 
 
