H∞ control of molten steel level in continuous caster

A design of the H^∞ controller for the molten steel level in a continuous caster is described. The controller design is considered to balance both the disturbance rejection and the robust stabilization. The adopted design has the input weight functions for the disturbances to adjust the closed-loop characteristics in the medium frequencies. The numerical examples show that the result of the adopted H^∞ controller had better performances than the conventional design without the input weight functions. The results of the experimental tests show that the level fluctuation by the proposed H ^∞ controller was lower compared with that by the conventional proportional integral derivative (PID) controller