Study On Modeling And System Identification Of 300 Four-High Rolling Mill

The reversible cold rolling mill is the typical model of modernelectro-hydraulic and mechanical systems. Research on its precise mathematicmodel is the precondition of system analyzing, designing and optimizingcontrol. Based on the HAGC system of the 300mm experimental rolling mill ofYanshan University, cooperated with system identification and modeling bymechanism, this paper constructs the complete model for the rolling mill.Considering such factors as deformation and eccentricity of roller, theinitial range of hydraulic cylinder, the plastic deformation of the strip and inputgauge, as well as their effects on the thickness accuracy, dynamic performancesof hydraulic control systems, according to the flow equation of slide valve, theflow continuity equation of hydraulic cylinder, the force balanced equation ofhydraulic cylinder with load, the electro-mechanical model is established.As it's difficult to determine some hydraulic system parameters, systemidentification is implemented to identify some parameters of HAGC system.First it gives analysis and comparison to Least Squares, Weighted LeastSquares, Extended Least Squares and Instrumental variables, then analysestheoretically the problems of how to realize the identification in computer.Secondly, it does experiments on the identification of electro-hydraulic positionservo system. The input signal is creased in computer. Compares theidentification results of RLS with ARX, found that the latter one have the betterprecision, then test the ARX model identification. Establishes the mathematicalmodel of the hydraulic system in the later method.