Systems and methods for the automated sensing of motion in a mobile robot using visual data

  • US 20040076324A1
  • Filed: 08/15/2003
  • Published: 04/22/2004
  • Est. Priority Date: 08/16/2002
  • Status: Active Grant
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First Claim
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1. A method of determining a motional state of a mobile robot, the method comprising:

  • retrieving pixel data for images taken at intervals from a camera that is coupled to the mobile robot;

    comparing pixel data for a first image to pixel data for a second image to generate a measure of a difference between the two images, wherein comparing comprises;

    filtering the first image pixel data with a gradient magnitude filter, where the gradient magnitude filter computes at least a spatial gradient;

    comparing the gradient-magnitude filtered first image pixel data to a first threshold;

    generating a binary map of the first image pixel data at least partly in response to the comparison of the gradient-magnitude filtered smoothed first image pixel data with the first threshold;

    filtering the second image pixel data with the gradient magnitude filter;

    comparing the gradient-magnitude filtered smoothed second image pixel data to a second threshold;

    generating a binary map of the second image pixel data at least partly in response to the comparison of the gradient-magnitude filtered second image pixel data to the second threshold; and

    comparing the binary map of the first image pixel data to the binary map of the second image pixel data to identify data for pixels that are different between the first image and the second image;

    using the comparison of the pixel data to count the number of pixel data identified as changed;

    comparing the count to a third predetermined threshold; and

    determining the motional state of the mobile object at least partly in response to the count.

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