Tension control system for hot strip mills

The looper control of a hot strip finishing mill is one of the most important control items in the hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension strongly interact with each other. There are many control schemes such as conventional, noninteractive, LQ, LQG/LTR, H_∞ and ILQ control in the looper control system. In this paper, we present the modeling for the looper of a hot strip finishing mill to control the tension of the strip and suggest the noninteractive (cross) and LQG/LTR control method