Analysis of contact instability in terms of passive physical equivalents

Ed Colgate*, Neville Hogan

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

193 Scopus citations


The authors explore the sources of and solutions to robot contact instability associated with force feedback. The behavior of several linear robot models is analyzed in terms of the properties of their admittances. Using the novel technique of passive physical equivalents, an explanation for the often-observed instability of a force-controlled robot contacting a stiff surface is offered, and it is shown that a fundamental limit exists to the efficacy of any force feedback controller implemented on a robot with noncolocated actuators and sensors. Suggestions for improved force control involving both mechanical design and compensator design are also presented.

Original languageEnglish (US)
Pages (from-to)404-409
Number of pages6
JournalProceedings - IEEE International Conference on Robotics and Automation
StatePublished - 1989
Event1989 IEEE International Conference on Robotics and Automation, ICRA 1989 - Scottsdale, AZ, USA
Duration: May 14 1989May 19 1989

ASJC Scopus subject areas

  • Software
  • Control and Systems Engineering
  • Artificial Intelligence
  • Electrical and Electronic Engineering


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