Strategy Of Flatness Control System Lag Compensation

In the process of flatness control in steel strip rolling, to get best state of dynamicsand robustness of control system possibly, the closed-loop controlling is adopted generally.Simply, according to the deviation of the measured data obtained from the flatnessmeasuring roll and the pre-set target, adjust the actuator repeatedly until minimizing thedeviation finally. However, the measured data can’t respect the actual value of currentflatness, but sometimes before, which makes the flatness control system of cold rollingbecome a time-delay system. So, the research about how to control the time-delay systemeffectively becomes one of the urgent problems to improve the accuracy of flatness controlsystem.The effective measure of time-delay system in flatness closed-loop control system isstudied in this article, at the same time, Dahlin algorithm and Smith algorithm arerecommended. Different factors which can influence the above algorithm control systemare studied, comparing with each other and analyzing the influences, appropriate measuresfor improvement are proposed.The advantages of forgetting factor method, parameter recursive estimation andaugmented recursive least squares method are integrated. The least squares method isimproved to augmented recursive least squares identification algorithm with forgettingfactor. The accurate online identification of system is achieved. Based on the identificationresults, the parameters of controller can be corrected automatically online, so the best stateof dynamic characteristic of control system can be achieved and the flatness is wellcontrolled. In order to make the system have a better dynamic characteristic relatively forkey influential factors, the advantages of Dahlin algorithm and Smith algorithm areconsidered and combined, the control system is improved rationally, and the needs ofindustrial production is satisfied. Contrary to that saturation of actuator output caninfluence the flatness control system, a new method about the feedback control: matrixanalysis method, is proposed. Considering dynamic characteristic of controller adequately,the feasible region of adjustment and the optimal adjustment of actuator are derived be mathematical methods, and the deviation of flatness can be eliminated maximumly.Contrary to the fluctuation of rolling force, striking the optional solution of joint control ofclosed-loop feedback control and feed-forward control of flatness, the optional adjustmentof two different controlling methods is distributed reasonably.Finally, utilizing the above effective measures, the simulation results are consistentwith actual situation, which prove the correctness of this research strategy, proposing basisfor the conversion of theory further.