The Integral Dynamic Model Building of 4-High Rolling Mill System and the Robust H∞ Controller Design of the Thickness Control System

摘要

In this paper,the integral dynamic model of 4-h mill is built which includes the rolling process model,the mill stand-rolls dynamic model and the dynamic model of hydraulic servo system.The three models are coupled and linearized,then the MIMO transfer function of 4-h mill system is obtained.Considering the quality of the product,the MIMO model is simplified and the thickness control system is derived based on thickness gauge.The H∞ robust controller is designed for the thickness control system based on the mixed sensitivity robust control theory.The weighting functions are selected based on genetic algorithm (GA).Simulation results and comparison with the effect of PI controller show that the robust controller designed has better disturbance attenuation performance for parameter uncertainty and external disturbance.The dynamics performances and stability of the thickness control system based on thickness gauge were improved significantly.