Iterative feedback tuning of PID parameters: comparison with classical tuning rules

We apply the Iterative Feedback Tuning (IFT) method to the tuning of PID parameters in applications where the objective is to achieve a fast response to set point changes. We compare the performance of these IFT-tuned PID controllers with the performance achieved by four classical PID tuning schemes that are widely used in industry. Our simulations show that IFT always achieves a performance that is at least as good as that of the classical PID tuning schemes, and often dramatically better: faster settling time and less overshoot. In addition, IFT is also optimal with respect to the presence of noise, whereas the other schemes are designed for noise-free conditions. The IFT method used here is a variant of the initial IFT scheme, in which no weighting is applied to the control error during a time window that corresponds to the transient response, and where the length of this window is progressively reduced. This method was initially proposed in Lequin (CD-ROM of European Control Conference, Paper TH-A-H6, Brussels, Belgium, 1997) and elaborated on in Lequin et al. (Proceedings of the 14th IFAC World Congress, Paper I-3b-08-3, Beijing, People's Republic of China, 1999, pp. 433-437). (C) 2003 Elsevier Science Ltd. All rights reserved.