Hot strip mill tension–looper control based on decentralization and coordination

Abstract Since tension and looper control is the key to successful operations in the hot strip finishing mill, several multivariable controllers have been applied. However, this leads to complicated controllers, which are hard to tune on site. This paper presents a new control method based on decentralization and coordination. First, interactions between tension and the looper are evaluated to ensure the applicability of decentralized control. Then, a decentralized controller based on the two-degree-of-freedom Internal Model Control (IMC) structure is applied. Moreover, impedance control is introduced to retrieve the coordinated action of the looper. The control scheme enables stepwise commissioning of control systems, which is very helpful for on-line tuning.