Research On Multivariable Decoupling Fuzzy PID Control Method Of Finishing Looper System In A Hot Rolling Mill

In the hot rolling production process,the finishing rolling looper device plays a vital role in the stability of the rolling process.It is mainly manifested in the dynamic adjustment of the amount of strips to absorb the excess redundant strips between the stands,and keep rolling steel with constant tension while maintaining a reference height.Furthermore,it can effectively avoid the production accidents such as steel jamming and work roll breaking due to the accumulation of strips.At present,most hot rolling mills is using traditional PID method to control the looper,and its control parameters are easy to adjust,the control method is flexible,and the reliability is strong.However,because the hot rolling looper control system is a complex system with non-linear and strongly coupled,the PID controller with fixed parameters cannot well meet the requirements of production for control accuracy.With the continuous development of control theory,the decoupling control methods and intelligent control methods such as fuzzy control have appeared,and their application to looper control can greatly improve the accuracy of looper control.This paper takes a finishing mill hydraulic looper system in a hot rolling mill as the research object.Starting from the practical application background,the multi-variable decoupling fuzzy PID control method is studied to improve the control performance of the system.The main work is as follows:(1)Introduce the production process of the hot rolling mill,draw forth the function of the looper equipment in the rolling process,and introduce the actual looper system according to the three dimensions of mechanical,hydraulic and automation;(2)With the help of theoretical modeling methods,use flow continuity equation,Newton’s second law,tension increment equation,torque balance relationship to model the hydraulic looper system;(3)The feedforward decoupling method is used to decouple the two controlled variables of the angle and tension of the looper model.The fuzzy controller of the looper system is designed in the decoupled system to obtain the fuzzy PID decoupling control strategy of the system;(4)Using Matlab software to simulate the designed fuzzy PID decoupling controller,and comparing with the control effect of traditional non-decoupling PID control,it verifies the effectiveness and superiority of the control strategy proposed in this paper.