Feedback Robustness in Structured Closed-loop System

This paper addresses the robustness of large-scale closed-loop structured systems in the sense of arbitrary pole placement when subject to failure of feedback links. Given a structured system with input, output, and feedback matrices, we first aim to verify whether the closed-loop structured system...

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Bibliographic Details
Published in:European journal of control Vol. 57; pp. 95 - 108
Main Authors: Gundeti, RaviTeja, Moothedath, Shana, Chaporkar, Prasanna
Format: Journal Article
Language:English
Published: Philadelphia Elsevier Ltd 01.01.2021
Elsevier Limited
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ISSN:0947-3580, 1435-5671
Online Access:Get full text
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Summary:This paper addresses the robustness of large-scale closed-loop structured systems in the sense of arbitrary pole placement when subject to failure of feedback links. Given a structured system with input, output, and feedback matrices, we first aim to verify whether the closed-loop structured system is robust to the simultaneous failure of any subset of feedback links of cardinality at most γ. Subsequently, we address the associated design problem in which given a structured system with input and output matrices, we need to design a sparsest feedback matrix that ensures the robustness of the resulting closed-loop structured system to simultaneous failure of at most any γ feedback links. We first prove that the verification problem is NP-complete even for irreducible systems and the design problem is NP-hard even for so-called structurally cyclic systems. We also show that the design problem is inapproximable to factor (1−o(1))logn, where n denotes the system dimension. Then we propose algorithms to solve both the problems: a pseudo-polynomial algorithm to address the verification problem of irreducible systems and a polynomial-time O(log n)-optimal approximation algorithm to solve the design problem for a special feedback structure, so-called back-edge feedback structure.
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ISSN:0947-3580
1435-5671
DOI:10.1016/j.ejcon.2020.05.009