Reconciling nu-Gap Metric and IQC Based Robust Stability Analysis

Research output: Contribution to journalArticle


This technical note elaborates on the flexibility of an approach that combines nu-gap metric and integral quadratic constraint (IQC) based analysis in the study of uncertain feedback interconnections of distributed-parameter transfer functions. It is established that a standard ν-gap ball robust stability result can be recovered within the blended IQC/nu-gap framework, which only requires the existence of ν-gap continuous paths within the uncertainty set of interest. This is achieved, in part, by showing that sufficiently small ν-gap balls are pathwise connected in the graph topology. A linear fractional characterisation of the ν-gap is a key ingredient. This characterisation is underpinned by a certain J-spectral factorisation, also shown to exist herein.


  • Sei Zhen Khong
  • Michael Cantoni
External organisations
  • External Organization - Unknown
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Control Engineering
Original languageEnglish
JournalIEEE Transactions on Automatic Control
Issue number8
Publication statusPublished - 2013
Publication categoryResearch
Externally publishedYes