Model Predictive Roll Gap Control in Cold Rolling with Piezoelectric Actuators

In cold rolling, a precise roll gap adjustment is indispensable for manufacturing strips with accurate thickness. This paper proposes a linear model predictive controller for roll gap adjustment in a cold rolling mill. As part of an automatic gauge control, the precise roll gap adjustment according to the incoming strip thickness profile is vital. The measurement of that profile is buffered, filtered with a zero-phase and length-based filter and converted to a reference trajectory to meet the needs of a model predictive controller. Knowing the roll gap model as well as the actuator dynamics, the model predictive controller can adjust the roll gap according to incoming strip thickness disturbances right on time. Piezoelectric actuators are used for fast and precise adjustment. Results obtained in a cold rolling mill of industrial scale are shown.