Flatness based open loop control for the twin roll strip casting process

Strip casting technology is the most recent innovative steel casting technology that integrates casting and rolling into a single production step. The strip thickness is supposed to be changed independently of the contact time of the molten steel with the rollers, which determines the quality of the produced steel strip. This leads to a decoupling problem which is difficult to tackle with classical control approaches due to the nonlinearity and the varying dead time occuring in the manipulated variables of the system. In order to steer the system between two operating points and for the startup procedure, a flatness based open loop control scheme is presented. Starting from the process model, the flatness of the system outputs is shown and the trajectory generation for the manipulated variables is described which ensure that the outputs follow the desired trajectories.