State-space solution of the standard H∞ control problem for strip mill gauge control

The main purpose of this paper is to design multiloop H_∞ controllers for a strip mill gauge control system. The two-Riccati state-space approach is applied to design H_∞ controllers for both the inner loop (roll force feedback loop) and the outer loop (strip gauge loop). To avoid order propagation of the outer loop controller, a model reduction method is applied after the design of the inner loop is completed, The plant considered in this paper is the same as that considered by Grimble (1995), but the design approach is different. In addition, the advantages of using a multiloop strategy (using both roll force measurement and gaugemeter feedback) are illustrated