Frequency Domain Identification of Multirate Systems: A Lifted Local Polynomial Modeling Approach

TL;DR

This paper introduces a novel frequency-domain identification method for multirate systems using local polynomial modeling, enabling accurate, bias-free, and efficient closed-loop system identification in a single experiment.

Contribution

It presents a new lifted local polynomial modeling approach for multirate systems that overcomes bias issues of traditional LTI methods and allows direct frequency-domain identification.

Findings

Accurate identification of multirate systems demonstrated

Method is faster and more reliable than existing techniques

Effective in closed-loop control scenarios

Abstract

Frequency-domain representations of multirate systems are essential for controller design and performance evaluation of multirate systems and sampled-data control. The aim of this paper is to develop a time-efficient closed-loop identification approach for multirate systems in the frequency-domain. The developed method utilizes local polynomial modeling for lifted representations of LPTV systems, which enables direct identification of closed-loop multirate systems in a single identification experiment. Unlike LTI identification techniques, the developed method does not suffer from bias due to ignored LPTV dynamics. The developed approach is demonstrated on a multirate example, resulting in accurate and fast identification in the frequency domain.