Decoupling and internal model control of non-square flatness control system and their applications
SONG Ming-ming1,2, LIU Hong-min1, WANG Dong-cheng1, XU Hui2, LIU Xiao-li2
1. National Engineering Research Center for Equipment and Technology of Cold Rolling Strip, Yanshan University, Qinhuangdao 066004, Hebei, China; 2. College of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan 056001, Hebei, China
Abstract：In order to develop the flatness control system of 1 420 mm six high UCM cold rolling mill which is not equipped with flatness closed-loop automatic control,a flatness automatic control system is built based on component flatness decoupling control with the development environment of Labview,and the flatness automatic control of the rolling mill is realized. Through the calculation and analysis of flatness adjustment, recognized that the roll tilting,and the non-symmetric work roll bending can effectively adjust the primary and cubic flatness components,the symmetric work roll bending,the symmetric intermediate roll bending and the intermediate roll shifting can effectively adjust the quadratic and quartic flatness components,and it is difficult to adjust the sixtic flatness components,so that the flatness control system can be determined to be a non-square control system with five inputs and four outputs,and unstable poles will appear in the process of non-square control system decoupling. A decoupling method is proposed to decompose unstable poles,which solves the unstable problem of non-square flatness control system decoupling. Using the non-square relative gain theory,the five inputs four outputs non-square control system is decomposed into a two inputs two outputs square system and a three inputs two outputs non-square system,simplifying the structure of the flatness control system. Because the installation position of the shape meter is a certain distance from the roll gap,the flatness control system has the problem of time delay,which increases the difficulty of controller design. Based on the combination of internal model control and Smith predictive control,a flatness IMC-Smith control model is proposed,which simplifies the controller design,solves the problem of the time delay of control system,and realizes the engineering application of non-square flatness control system. The industrial application shows that the system has reliable performance and can meet the requirements of on-site online rolling. The flatness after rolling can meet the requirements of subsequent processes. The flatness control effect is significantly improved compared with that of manual operation.
宋明明, 刘宏民, 王东城, 徐辉, 刘晓立. 非方板形控制系统解耦及内模控制与应用[J]. 钢铁, 2023, 58(5): 92-103.
SONG Ming-ming, LIU Hong-min, WANG Dong-cheng, XU Hui, LIU Xiao-li. Decoupling and internal model control of non-square flatness control system and their applications[J]. Iron and Steel, 2023, 58(5): 92-103.
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