New visualization of the Evans root locus. Gain plots

Thomas R. Kurfess, Mark L. Nagurka

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations


This paper proposes an alternate graphical representation of the Evans root locus, a well known controls technique for stability and performance evaluation. It shows via a series of transformations a set of Gain Plots (GPs) that depict the polar coordinates, i.e., magnitude and angle, of each closed loop system eigenvalue in the complex plane as a function of proportional gain. The GPs impart significant insight for determining the values of gain that render a closed-loop system either stable or unstable, and are useful tools for identifying closed-loop designs meeting performance specifications. The GPs are applicable to single-input, single-output and multiple-input, multiple-output feedback systems.

Original languageEnglish
Title of host publicationRobust Control of Mechanical Systems
Subtitle of host publicationTheory and Applications
PublisherPubl by ASME
Number of pages8
ISBN (Print)0791808548
StatePublished - 1 Dec 1991
Externally publishedYes
EventWinter Annual Meeting of the American Society of Mechanical Engineers - Atlanta, GA, USA
Duration: 1 Dec 19916 Dec 1991

Publication series

NameAmerican Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC


ConferenceWinter Annual Meeting of the American Society of Mechanical Engineers
CityAtlanta, GA, USA

ASJC Scopus subject areas

  • Software
  • Mechanical Engineering


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