STATE-SPACE SOLUTION OF THE STANDARD H-INFINITY CONTROL PROBLEM FOR STRIP MILL GAUGE CONTROL

The main purpose of this paper is to design multiloop H-infinity contr ollers for a strip mill gauge control system. The two-Riccati state-sp ace approach is applied to design H-infinity 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 mode l reduction method is applied after the design of the inner loop is co mpleted. The plant considered in this paper is the same as that consid ered by Grimble in 1995, but the design approach is different. In addi tion, the advantages of using a multiloop strategy (using both roll fo rce measurement and gaugemeter feedback) are illustrated.