Shifting Method for Relay Feedback Identification

Abstract

This paper introduces a method extending possibilities of the relay feedback identification of dynamic systems describable by their transfer function. The proposed “shifting” method enables to estimate three points on a plant frequency response from a single relay feedback test without using the FFT algorithm. The approach enables to estimate up to five parameters of the transfer function from sustained oscillations obtained by one relay test. For this purpose the method uses a biased relay. The introduced technique offers a tool for a large class of common control problems. The applicability of the proposed frequency-response identification method is demonstrated by estimating five parameters of the anisochronic model and by estimating three points on the frequency response of the physical model called “Air Aggregate”. All experiments were performed in Matlab/Simulink programming environment.