IMC based automatic tuning method for PID controllers in a Smith predictor configuration

In this paper, a new approach is presented based on relay autotuning of a plant to find parameters for its control using a Smith predictor. A Smith predictor configuration is represented as its equivalent internal model controller (IMC) which provides the parameters of the proportional-integral (PI) or proportional-integral-derivative (PID) controller to be defined in terms of the desired closed-loop time constant, which can be adjusted by the operator, and the parameters of the process model. This means that only one parameter, namely the desired closed-loop time constant, is left for tuning, assuming that the model parameters have been obtained from a relay autotuning. The ISE criterion was used to find the filter parameter, and simple equations were obtained to tune the Smith predictor. The method is very simple and has given improved results when compared with some previous approaches. © 2003 Elsevier Ltd. All rights reserved.