Robust H∞ control for the looper system in hot strip mills

The looper control is important control items in hot strip mills because it can affect the strip quality as well as strip threading. The loopers are placed between each rolling stands, it is very important to control stably both a looper and strip tension at their each target values. In the paper, the problem of designing an innovative control scheme for the looper of the hot strip mills is considered,and H∞ controller for looper system was designed. Design method of state feedback is described in this paper, also showing strong robustness. At last, we compare the performance of conventional PI control with the proposed H∞ control.