We describe a looper controller design for a hot strip finishing mill in steel plants. To ensure strip quality, it is very important to control the tension of the hot strip finishing mill. However, because of a mutual interaction between the looper angle and the strip tension, it is difficult to control the looper system. Previous researches examined only the operation of a single stand. But it is not sufficient to examine the operation and effect of whole stands because the operation is wholly interdependent. In this paper, we present a full model of the hot strip finishing mill in order to more effectively control strip tension. We propose several control methods for the full-stand hot strip finishing mill, denoted as conventional PI, PI with cross gain, and CDM PID control. In the real plants, there are some problems by using higher order controllers such as LQ, LQG and H{sub}∞. By comparison, the PID controller is very simple and easy to apply to all real plants. To that end, we present our findings on PID controls and their potential use in the hot strip finishing mill.
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