PI autotuners based on biased relay identification

The paper describes an automatic tuning procedure for a wide class of continuous-time systems without and with time delays. Every auto-tuning method has two basic steps. The first one is experimental and yields an estimated model. The second step consists in a design procedure of controllers. The developed auto-tuning procedure identifies a first order estimation model obtained by a biased relay feedback test. The consecutive design is based on a general solution of Diophantine equations and results in a PI-like controller. Moreover, the Diophantine equation approach gives a scalar tuning parameter which is adjusted according to the equalization of weighted moments. Copyright © 2005 IFAC