Multiple frequency response points identification through single asymmetric relay feedback experiment

Abstract

In this paper a methodology to identify several points of the frequency response of a system using a single experiment is proposed. The identification is performed using the information obtained from an asymmetric relay feedback experiment. The frequency response points that are estimated correspond to the fundamental oscillation frequency induced by the asymmetric relay and its harmonics. The method is easy to implement since it only requires linear algebra operations, but relies on a proper data selection, which is largely studied, to obtain the most accurate results. The proposed method allows a Least Squares formulation, which has also been studied, and presents some benefits in terms of accuracy for certain cases. The presented results are validated experimentally using a practical identification case.