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Robotic acquisition of objects by means including histogram techniques

  • US 4,613,269 A
  • Filed: 02/28/1984
  • Issued: 09/23/1986
  • Est. Priority Date: 02/28/1984
  • Status: Expired due to Fees
First Claim
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1. A robot system for acquiring randomly-arranged workpieces, comprisinga robot assembly including a hand, and a controller for controlling the movement of the hand to positions to successively grasp workpieces of given size and transfer them to a predetermined site,a video imaging device to provide a video signal representing a brightness image of the randomly-arranged workpieces, anda computer programmed to be responsive to the video signal from the imaging device and operative to modify the image, to compute a holdsite on a workpiece in the image, and to command the robot assembly to grasp the workpiece and transfer it to said predetermined site,said video imaging device including a video range expander for selecting and amplifying a range of video signal amplitudes between a gray threshold level and a white clipping level,said computer including program means to quantize the selected video signal having said range of amplitudes into digital pixels within a plurality of windows all having a size proportional to the size of the workpieces, said means to quantize the selected video signal including means to generate the same number of digital pixels of the image within the window regardless of the size of the window, and to enhance the quantized image by making all pixels having a brightness intensity less than a threshold intensity T equal to zero, and retaining the brightness intensities of all pixels above the threshold T, said threshold intensity T being computed by program from an intensity histogram so that T exceeds the intensity of the most numerous dark pixels by a predetermined fraction of the difference between the intensity of the most numerous dark pixels and the intensity of the most numerous bright pixels.

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