Robustness Margins Separating Process Dynamics Uncertainties

Per-Ola Larsson, Tore Hägglund

Research output: Contribution to conferencePaper, not in proceedingpeer-review


In controller design, not only set-point tracking and disturbance rejection can be considered, also robustness towards process uncertainties is a key issue. In this paper, new robustness measures that divide uncertainties into dead time and non-dead time uncertainties, are presented. It is shown, to
the contrary of classic measures such as phase/gain/dead time margins, to guarantee stability towards simultaneous process changes, but at the same time being more flexible and less conservative than the robust control framework. The measures depend on extended sensitivity functions and are well illustrated in a Nyquist diagram giving valuable insight. Procedures to
calculate the robustness margins are presented and examples are given.
Original languageEnglish
Publication statusPublished - 2009
EventEuropean Control Conference, 2009 : ECC´09 - Budapest, Hungary
Duration: 2009 Aug 232009 Aug 26


ConferenceEuropean Control Conference, 2009

Subject classification (UKÄ)

  • Control Engineering


  • Robustness
  • Time Delay
  • Uncertain systems
  • Stability


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