Research On Two Dimensional Repetitive Control System Of Roll Eccentricity

With the rapid development of science and technology,various industries need more and more high-precision plate and strip to meet the needs of manufacturing and production.However,due to the lack of existing production technology in China,some high-precision plate and strip can not be produced and need to rely on imports.Therefore,in order to improve the production technology,it is very meaningful to study the control accuracy of rolling mill thickness control system.Now roll eccentricity is becoming an important factor affecting the accuracy of plate thickness.This paper makes an in-depth study on this problem.Learn the manufacturing and rolling process of rolling mill,and summarize two types of causes of roll eccentricity.By analyzing the rolling model of the rolling mill,the specific mathematical expressions of the influence of the two causes on the plate thickness are derived.On this basis,the roll eccentricity compensation control is deeply studied.In the extraction of roll eccentricity signal,the method of ensemble empirical mode decomposition is used to denoise the sampled rolling signal,and then the windowed fast Fourier transform is used to determine the eccentricity frequency composition of the eccentricity signal and obtain the mathematical expression.To compensate the periodic roll eccentricity signal,a two-dimensional three-step repetitive control method is introduced into the plate thickness control system of rolling mill.Firstly,an output feedback channel is added to the conventional two-dimensional repetitive control model,and the original learning process is divided into two parts: input feedback learning of controlled system and output feedback learning of controlled system.Then,the system model based on this structure is established and its state space model is obtained.Then,the linear matrix inequality(LMI)conditions for the stability of the system are derived by using the Lyapunov second method stability theory.Finally,the numerical simulation results show that the control theory can track or suppress the roll eccentricity signal,and improve the control accuracy of the system.