Controller Design by Frequency-Domain Fictitious Reference Iterative Tuning Using Sliding DFT

Abstract

In this paper, we propose a method for online controller adjustment by a fictitious reference iterative tuning (FRIT) of a frequency domain using sliding discrete Fourier transform (DFT). We have extended the FRIT to correspond time delay and characteristic variation of a control object. A sliding DFT was used to correspond to the time delay of the controlled object. In addition, we have optimized the method using a recursive least-squares algorithm to determine the controller gains online. In this study, we utilized an algorithm that was designed in a two-degree-of-freedom (2DOF) control system. We have experimentally verified the effectiveness of the proposed method. The proposed method can correspond to the time delay of a controlled object. In addition, it can also correspond to characteristic variations of a control object.