Multivariable IMC-PID Control Algorithm

Nowadays,single loop PID controllers are still being employed in about 80%to 90%of the control systems.However,interactions exist in many complex industry systems.The single loop PID strategy could not deal with this problem effectively.In order to improve the control performance of the MIMO systems,the strategies for MIMO processes have been studied much, in the hope that the effective closed loop control of coupling systems can be achieved,and the economy benefits can be enhanced,the energy consumption will be reduced,and the high quality of products could be guaranteed.Internal model control(IMC)has excellent servo performance,high robustness,particularly in case of model uncertainty,effective hog-tieing,and so on.IMC-PID control has the advantages of IMC,and has a simple construction.It can be used in plants in existence and need no hardware modify.This paper mainly discussed IMC strategies and PID transform.SISO IMC is widely used in practice.Firstly,the IMC and IMC-PID for SISO system are discussed.The comparison between PID and IMC-PID is made to show that IMC-PID is a much more effective controller.Secondly,aims at the characteristics of MIMO system,the IMC for a multivariable system is designed.The decoupling IMC is applied for MIMO systems based on the interaction of MIMO process.An IMC-PID transform strategy for MIMO system is proposed using Model identify and NLJ algorithm.A mass of calculations are avoided.Simulation results show that this method has high precision.Lastly,integrate modeling theory of AIC(adaptive inverse control)with IMC theory,a new control system is designed.With this method,Process model and inverse model are identified with adaptive algorithm,and the struction of IMC is used.Simulation results show the effect of this method.