Automatic Gauge Control under Laterally Asymmetric Rolling Conditions Combined with Feedforward

The most common and well proven control strategy for thickness control in industrial rolling mills is the automatic gauge controller (AGC). However, it is still unclear how to use AGC for the control of asymmetries in lateral direction. How should the controller react to different thickness estimations at both sides of the mill? Such laterally asymmetric rolling conditions may originate from strip track-off, asymmetric friction in the mill stand, or a wedge-shaped entry profile of the strip thickness. In this paper, three control approaches are discussed. Two different setups of AGC are compared and a feedforward (FF) approach is developed for lateral asymmetries of the entry thickness profile. Simulation studies based on a validated mill stand model demonstrate the benefit of combining AGC with a feedforward controller to compensate for asymmetries.