Research On Robust Stability, Adaptive Dead-Time Compensator And H_∞ Robust Control For Uncertain Processes With Large Dead-Time

This dissertation,which consists of ten chapters,contains six parts. The first part contains the first,the second,and the third chapter. In the first chapter,the developing history of dead-time process control,all control methods and problems being widely researched are introduced briefly. The second chapter discusses the concepts of dead-time and inertial lag by several typical processes,the internal and outer mathematical descriptions and stability problems of the dead-time processes.The part two consists of chapter four and chapter six. In chapter four,a kind of object reference parameter adaptive dead-time compensator (ORPADTC) is proposed,and its construction and design methods are described. This compensator can be used for all uncertain processes with large dead-time (UPLDT) which satisfy some stability conditions. In the compensating system,in order to make the model match the being controlled process,the predictive output follow that of the uncertain and perturbed part of the being controlled process and the model output trace that of the being controlled process,a group of models are used to imitate the uncertain and perturbed part of the being controlled process. The ORPADTC model can always match the real process and the UPLDT output,which can be used as the feed back signal of the control system,can be predicted. The ORPADTC completely solves the problems,sensitive to the error of the model parameters and the low power against disturbance,which exist in the traditional Smith compensator. The design methods of the ORPADTC,which are based on Lyapunov stability and Popov hyperstability,are discussed. In the chapter six,simulations are done for a few typical first order UPLDT and second order UPLDT. The simulation results prove that the ORPADTC has good power in dead-time compensating and adaptive tracing when the process being controlled has terrible uncertainty and parameter perturbation,and it is easy to design.The third part contains chapter five and seven. In chapter five,a construction of closed loop control system is given for dead-time compensated UPLDT. To the point of parameter uncertainty and perturbation,double plus and double multiply expressions are presented. Problems,which are the robust stabilization,the normal H control,the minimum sensitivity and mix sensitivity control,are discussed for the dead-time compensated UPLDT.ABSTRACTIn the seventh chapter,H robust control simulations are done for typical first order and second order UPLDT. The simulation results prove that the H robust controlled systems,which are compensated by the ORPADTC,have idea robust stability and dynamic performance.In the fourth part,the chapter eight,a kind of expert cascade controller (EEC) construction and its design method are proposed. The EEC can be built on not only real model control theories but also expert knowledge and operator experience. It is good at controlling the processes with parameter uncertainty and perturbation. The EEC system has been successfully adopted in a disinfecting process of biological pharmacy.The fifth part,chapter nine,discusses the stability problems of a class of singularly perturbed systems (SPS). Some processes are complex high order ones. They usually behave like stable low order ones. In some typical conditions,they probably become unstable high order systems. These potential dangers often cause terrible accidents. Recent years,people have pay high attention to the SPS. In this chapter,the stability judgements are proposed for the SPS in four conditions respectively. They can offer the upper bound of the dead-time and the perturbed parameter. An application example shows that the judgements are easy to use.The final part,the tenth chapter,summarizes the works of the dissertation and introduces the remanent problems to be solved.