A multivariable robust controller for a pilot plant

In this paper, a pilot plant located at our laboratory is initially presented. The system consists of industrial components (a water tank, a resistor, pneumatic valves and a heat exchanger) and the main goal is to control some of its temperatures. Due to the high nonlinearity introduced by the heat exchanger, a model of the plant is obtained at an operating point and an analysis is made to obtain some properties of its controllability. Results of this analysis are used to synthesize a multivariable H_∞ controller to keep robust the plant against disturbances and small changes of the operating point. The performance of the controller is finally presented with experimental results.