Optimal multivariable looper control for hot strip finishing mill

An optimal multivariable looper control system based on optimal-regular theory has been developed for hot-strip finishing mills. Loopers of the mill are installed between stands and are in many cases driven by motors. The goal of looper control is to maintain product quality at a high level by stabilizing the rolling operation. Stability is achieved by keeping the looper angle and tension applied to the strip at given reference values. Control-system features are outlined. It is shown that the control system can maintain a relatively constant strip tension without operator intervention in the presence of rapid change of hydraulic screw down such as automatic gauge control operation. Data obtained at a commercial plant demonstrates that optimal multivariable looper control is more effective than conventional control or noninteractive control.<>