Detecting robot stasis

  • US 8,417,383 B2
  • Filed: 05/31/2007
  • Issued: 04/09/2013
  • Est. Priority Date: 05/31/2006
  • Status: Active Grant
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First Claim
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1. A coverage robot comprising:

  • a drive configured to maneuver the robot as directed by a controller in communication with the drive;

    a swivel caster assembly coupled to the drive and comprising;

    a stasis indication wheel freely rotatable about a horizontal axis parallel to a traveling surface, the stasis indication wheel defining a first reflective portion and a second reflective portion, the second reflective portion being substantially less reflective than the first reflective portion;

    a wheel housing mounted on a freely rotatable shaft positioned at an angle relative to the horizontal axis, the wheel housing supporting the wheel such that rotation of the shaft causes the wheel to swivel on the traveling surface; and

    a suspension supporting the wheel housing and permitting movement of the wheel in a direction other than rotation about the horizontal axis and swiveling on the traveling surface;

    a signal emitter disposed remotely from the wheel and positioned to direct a signal that sequentially is intercepted by the first and second reflective portions of the wheel; and

    a signal receiver co-located adjacent the signal emitter to receive the signal as reflected by the first and second reflective portions of the wheel as the wheel freely rotates about the horizontal axis as the wheel swivels on the traveling surface, and as the wheel moves in the direction permitted by the suspension,wherein the strength of the reflected signal received by the receiver changes based at least in part on rolling transitions between the first reflective portion and the second reflective portion of the wheel in multiple swivel positions and along the movement permitted by the suspension.

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