Exact Instability Margin Analysis and Minimum-Norm Strong Stabilization -- phase change rate maximization --

Fuente: arXiv
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Main Authors: Hara, Shinji, Kao, Chung-Yao, Khong, Sei Zhen, Iwasaki, Tetsuya, Hori, Yutaka
Format: Preprint
Published: 2022
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_version_ 1866912526036369408
author Hara, Shinji
Kao, Chung-Yao
Khong, Sei Zhen
Iwasaki, Tetsuya
Hori, Yutaka
author_facet Hara, Shinji
Kao, Chung-Yao
Khong, Sei Zhen
Iwasaki, Tetsuya
Hori, Yutaka
contents This paper is concerned with a new optimization problem named "phase change rate maximization" for single-input-single-output linear time-invariant systems. The problem relates to two control problems, namely robust instability analysis against stable perturbations and minimum-norm strong stabilization. We define an index of the instability margin called "robust instability radius (RIR)" as the smallest $H_\infty$-norm of a stable perturbation that stabilizes a given unstable system. This paper has two main contributions. It is first shown that the problem of finding the exact RIR via the small-gain condition can be transformed into the problem of maximizing the phase change rate at the peak frequency with a phase constraint. Then, we show that the maximum is attained by a constant or a first-order all-pass function and derive conditions, under which the RIR can be exactly characterized, in terms of the phase change rate. Two practical applications are provided to illustrate the utility of our results.
format Preprint
id arxiv_https___arxiv_org_abs_2202_09500
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Exact Instability Margin Analysis and Minimum-Norm Strong Stabilization -- phase change rate maximization --
Hara, Shinji
Kao, Chung-Yao
Khong, Sei Zhen
Iwasaki, Tetsuya
Hori, Yutaka
Systems and Control
Optimization and Control
This paper is concerned with a new optimization problem named "phase change rate maximization" for single-input-single-output linear time-invariant systems. The problem relates to two control problems, namely robust instability analysis against stable perturbations and minimum-norm strong stabilization. We define an index of the instability margin called "robust instability radius (RIR)" as the smallest $H_\infty$-norm of a stable perturbation that stabilizes a given unstable system. This paper has two main contributions. It is first shown that the problem of finding the exact RIR via the small-gain condition can be transformed into the problem of maximizing the phase change rate at the peak frequency with a phase constraint. Then, we show that the maximum is attained by a constant or a first-order all-pass function and derive conditions, under which the RIR can be exactly characterized, in terms of the phase change rate. Two practical applications are provided to illustrate the utility of our results.
title Exact Instability Margin Analysis and Minimum-Norm Strong Stabilization -- phase change rate maximization --
topic Systems and Control
Optimization and Control
url https://arxiv.org/abs/2202.09500