A modified relay-feedback parameterization of time-delay models: Theory and application

Abstract

The well-known on/off relay-feedback identification test suffers from two imperfections. First, the parameters estimation does not bring a sufficient accuracy; second, a single test enables to quantify only two unknown model parameters. In this paper, two possible approaches dealing with these problems are attacked. Namely, the Autotune Variation Plus (ATV+) procedure introducing an additional artificial delay is utilized for a multiple-points model parameterization, and, the use of a saturation relay and a relay transient experiment with the Discrete Time Fourier Transform (DTFT) aid a better parameters estimation. The novelty of this contribution resides in that these methodologies are utilized with the combination with Linear Time-Invariant Time Delay Systems (LTI TDS) and their models. In our recent papers, theoretical aspects of the techniques were introduced and discussed, separately from other contributions dealing with a laboratory application of the saturation relay based approach. Both, theoretical and practical issues are summarized in this paper in a comprehensive presentation.