Abstract: In order to build high accuracy integral dynamic models of rolling mill system, apply advanced control theory in the traditional rolling field and improve the quality and precision of strip, dynamic model of gauge control system of 4-h mill is built, including the rolling process model, the mill stand-rolls dynamic model and the hydraulic servo system model. The three models are coupled and linearized, then the multiple input multiple output (MIMO) linear transfer function model of 4-h mill system is obtained. Simplify the MIMO linear model, considering the quality of the product, the plate thickness control system based on thickness gauge monitoring is obtained. The H∞ robust controller is designed by using the H∞ mixed sensitivity robust control theory. The weight functions are selected based on genetic algorithm. Simulation results and comparison with the effect of proportional integral derivative (PID) control show that the H∞ robust controller designed has better disturbance attenuation performance for parameter uncertainty and external disturbance. The dynamic performances and stability of the thickness control system are improved significantly.

Key words: Dynamic modeling, Genetic algorithm, H∞ mixed sensitivity, Rolling process