Generalized Relay Shifting Method for System Identification

Abstract

The paper describes an improved relay identification method, which enables the estimation of the parameters of a transfer function with various structures (stable, unstable, non-minimum phase, integrating, time delay systems, etc.) from a single relay feedback test. This identification approach follows the original shifting method and offers new possibilities. The proposed identification is demonstrated on a very versatile second-order time-delayed model and on systems with different structures. The proposed approach can be used for the tuning of PID controllers. The shifting method was implemented into a PLC Tecomat Foxtrot and used to control the laboratory apparatuses called “Air Aggregate”, “Water Levitation” and “Air Levitation”