Model-Based Feedback Control

Development Process

The first step in the development of a model-based controller is the development of a physical model which accurately reflects the actual behavior of the system to be controlled. For example, for a Rapid Thermal Processing System (RTP) a detailed thermal model of the system is developed. The model may contain physical variables whose values are not known in advance (e.g., heat transfer coefficient) and are identified from experimental data. A comparison of the model response with the actual system output provides a measure of model accuracy.

The next step in the cycle is the development of the model-based controller. Using the model, we use a variety of advanced feedback control designs to derive candidate controllers. The closed-loop system is then simulated in a graphical block diagram simulation environment (MATLAB® or MATRIXx) to assess the relative merits of various candidate controllers.

Once a satisfactory controller has been identified which meets the specifications (e.g. temperature uniformity for RTP), real-time C code is generated automatically to run on a rapid prototyping platform which controls the equipment directly. The controller's performance on the actual equipment is then determined, and further design iterations are carried out if necessary.

Our experienced engineers ensure seamless integration of this optimized subsystem controller into the existing control architecture of the complete system.