On-line controller tuning for unstable systems

A simple method for tuning controllers on-line for unstable processes is proposed. The step response data of the closed loop system with a proportional controller gain is used to identify model parameters of an unstable first order plus time delay transfer function. Reported tuning formulae for PI controllers for unstable systems are applied to obtain the controller parameters. The response of the closed loop system with the controller settings of the identified model is compared with that of the actual system's controller parameters. Copyright © 1995 Elsevier Science Ltd. All rights reserved.