IQC-based robustness analysis of discrete-time linear time-varying systems

J. Micah Fry, Mazen Farhood, Peter Seiler

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


The paper investigates the robust stability and performance of uncertain linear time-varying (LTV) systems using an integral quadratic constraint (IQC) based analysis approach. Specifically, previous theoretical work on IQC-based robustness analysis of linear time-invariant (LTI) systems is extended to discrete-time LTV systems. In the case of a general LTV nominal system, the analysis solution is provided in terms of an infinite-dimensional convex optimization problem. This optimization problem reduces into a finite-dimensional semidefinite program when the nominal system in question is finite horizon, periodic, or, more generally, eventually periodic. Finally, the results are applied to an unmanned aircraft control system executing an aggressive maneuver, where the developed techniques are used to find the region in which the aircraft is guaranteed to reside at the end of its planned trajectory.

Original languageEnglish (US)
Pages (from-to)3135-3157
Number of pages23
JournalInternational Journal of Robust and Nonlinear Control
Issue number16
StatePublished - Nov 10 2017

Bibliographical note

Funding Information:
This material is based upon work supported by the National Science Foundation under Grant Number CMMI-1351640 and the Naval Air Systems Command under Contract Number N00421–16–2–0001. Special thanks is also due to Mark Palframan for his assistance with code development and implementation.

Publisher Copyright:
Copyright © 2017 John Wiley & Sons, Ltd.


  • control
  • discrete-time systems
  • integral quadratic constraints
  • linear fractional transformation
  • robustness analysis
  • time-varying systems


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