Process control of a laboratory plant for direct casting of thin steel strips

The process control of a double roller laboratory plant for continuous casting of thin steel strips is presented. To describe the dynamics of the solidification and forming process a nonlinear state-space-model has been developed. On the basis of this model a process controller with the force as the controlled variable has been designed and applied to the laboratory plant. This controller ensures reliable regulation of the process as well as the production of steel strips with tolerable variations in thickness. The paper also deals with starting the process which is difficult to handle. This task is treated as an optimal control problem. Its solution is given as a nonlinear two-point boundary value problem which is solved by means of a gradient method