Roll Force AWC and RHC Tension Control in Hot Strip Mills

This paper proposes a new width control system composed of a RF (roll force) AWC (automatic width control) in the roughing mill and a RHC (receding horizon control) with a 4SID (subspace-based state space system identification) model identifier. The RF AWC is designed by the control model on the basis of a gauge meter equation using the roll force of a vertical mill. The RHC is employed to satisfy the constraints on the control input/state, guarantee the stability, and attenuate the effect of the disturbances. It is shown through the field test of the Pohang no.1 hot strip mill of POSCO that the width margin is considerably improved by the proposed control scheme.