Passive robots and haptic displays based on nonholonomic elements

Michael Peshkin*, Ed Colgate, Carl Moore

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


We describe a new architecture for passive robots and haptic displays, which we call a programmable constraint machine (PCM). An n-dof PCM can, under computer control, exhibit constraints (smooth, impenetrable virtual surfaces of dimensionality < n), or it can allow free n-dof motion. At the heart of the PCM is a nonholonomic element, which is used as a continuously variable transmission (CVT). A rolling wheel, for instance, can be used as a CVT. A prototype 2-dof cartesian PCM has been built, using a single rolling wheel, We sketch PCMs of higher dimensionality. A rolling wheel may be thought of as a translation CVT, coupling the x and y velocities of its center by a transmission ratio which is the tangent of its steering angle, Its utility in a cartesian PCM motivates interest in a rotational analog for revolute architectures. We develop a novel rotational CVT which couples two angular velocities by an adjustable ratio.

Original languageEnglish (US)
Pages (from-to)551-556
Number of pages6
JournalProceedings - IEEE International Conference on Robotics and Automation
StatePublished - Jan 1 1996

ASJC Scopus subject areas

  • Software
  • Control and Systems Engineering

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