Width Control System for Hot Strip Mills Based on Multivariable Control

Abstract

To attain a successful width control for hot strip mill, it is important to control a width at each stand preventing excessive tension imbalance for some specified stands.
Our research goal is to develop a multivariable control algorithm for the new width control system. In the proposed algorithm, the width is controlled by modifying the inter-stands tension, which value is derived from the measured width and the on-line calculated width. An optimal control principle is applied and the tension balance can be maintained by tuning the weighting matrix in the performance index. The on-line control algorithm is designed such that the tension modification value can be obtained in short time, compared with the optimal regulator. This calculation is realized using a formula manipulating procedure and the control performance is same to that by the optimal regulator.
The control system based on this algorithm has been applied to the hot strip mill and the width deviation can be remarkably reduced than before.