Regulation of the mold level using a vacuum in a steel continuous casting process

To regulate the level of molten steel in the mold of a continuous casting process, a control scheme is proposed in which the pressure in the vacuum chamber of the tundish is employed as control input. When the feedback linearising technique is employed it yields an unusual control law, in which the link between the time derivative of the mold level and the output error is not linear; in this case, the asymptotic stability of the system is not guaranteed. To ensure asymptotic stability, the correctness of the control law is analysed and a modified control law proposed. Numerical simulations show the adequacy of the dynamic performance of the modified control law, and that is feasible to extend the feedback linearising technique to design controllers for a certain class of nonlinear systems.