Gauge-Looper integrated optimal control for hot strip finishing mills based on sliding mode control

Abstract

Gauge-Looper and tension are controlled independently in the conventional control strategies, which are not able to deal with the external disturbance. Many researchers have proposed and applied a variety of control schemes for this problem, but the increasingly strict market demand for strip quality requires further improvements. This work describes a sliding mode control (SMC) strategy that realizes the optimal control of a automatic Gauge control and Looper control integrated system. Firstly, a state-space model of Gauge-Looper integrated system was established based on a 1700 mm tandem hot mill. Then, In order to achieve the desired dynamical performance of Gauge-Looper integrated system, the sliding mode surface and control law of SMC controller was designed. Simulation experiments for a traditional PID controller and the proposed SMC controller were conducted using MATLAB/Simulink software. The simulation results show that when the system is disturbed, the traditional controller produces a Gauge fluctuation of 0.136 mm and tension fluctuation of 1.177 MPa, which is unacceptable in hot strip mills. The SMC controller restricts the Gauge fluctuation to less than 0.047 mm, and the tension fluctuation is less than 0.382 MPa in all cases.