ROBUST CONTROL OF A SOLIDIFICATION PROCESS WITH PARAMETRIC UNCERTAINTY

Robust control of a solidification process is considered. In solidification processes, the properties of the solidified material are significantly determined by the solidification rate, defined as the time derivative of the solid/liquid interface position. Most often the position can not be measured directly, and thus the interface position must be estimated in order to employ feedback control. The solidification model has a variable structure where the state equations depend on the interface position. An observer based on a linearized model is developed. A gain-scheduled PI-controller is implemented, and the robustness properties are tested for parametric uncertainty in the model.