Study On Internal Model Control Of Unstable Systems With Time-Delays

With the development of modern engineering, varieties of manufacturing processes have defined as muitivariable control systems with time delays. Therefore, a superior decoupling and control strategy for muitivariable control systems with time delays have became the most needed advanced control technology at present. For the advantages of simple design theory, fast response speed and excellent robustness under the circumstances of models unmatched, Internal Model Control(IMC) theory shows powerful advantage of solving control problems with multivariable systems (MIMO). This paper's mainly purpose is to study and research the IMC theory, finally find a simple and practical control structure for muitivariable control systems with time delays.Based on the discussion of the IMC's basic theory, structure and design method of controller, this article discussed the application of IMC in time-delay systems. Through the comparison of different time-delay links' approximation, the all-pole approximation got better approximation effcet, then the general IMC-PID controller formula based on time-delay approximation was deduced. Then the improved IMC structure and controller tuning methods were adopted to control one order and high order unstable processes with time-delay, the simulation results indicated the advantage.For the multivariable square systems with time-delays, three kinds of IMC design methods are introduced, which are decentralized IMC control based on RNGA, process decoupling IMC control based on decoupling controller and IMC controller, controller decoupling IMC control based on P-norm reversed decoupling links. The simulations showed that the third method has better decoupling effect and system robustness.For the non-square systems, the squarlized methods of non-square systems and the control methods are discussed. A new loop pairing method used for non-square system is proposed, which is Non-square Relative normalized gian array. The simulation results showed the advantages of this method.