Model Predictive Controller for Strip-Tracking during Tail-Out of the Finishing Mill

Strip tracking problems at the hot strip mill sometimes occur at the finishing mill during tail-out. These errors are believed to be a major cause of pinches. To reduce the severity and number of pinches, a tilt controller has been designed to minimize DS-OS roll force differences, using a Model Predictive Controller (MPC), during tail-out. This paper describes its design and implementation. The controller comprises a strip tracking model. Using this model, the MPC computes real-time the right tilt corrections to minimize the roll force difference during tail-out, while respecting the constraints on the maximal tilt control actions. Also constraints on the rate of variation of the tilt corrections are taken into account. The controller has been implemented in the Level 1 software of the hot strip mill of Tata Steel in IJmuiden, the Netherlands. Results of the cold commissioning tests are presented.