AUTOMATIC TUNING OF DIGITAL CONTROLLERS WITH APPLICATIONS TO HVAC PLANTS

It has been demonstrated that PID controllers can be tuned effectively based on an experiment with relay feedback. This paper describes a tu ning method for a general digital controller based on relay feedback. The control design method is based on pole placement. An interesting f eature is that the sampling period and the desired closed-loop poles a re determined from the experiment. The method is also suited for pretu ning of adaptive algorithms. The paper describes the basic ideas, whic h are illustrated by simulations. Results from tests on HVAC (heating, ventilation and air-conditioning) plants are also reported.