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Method and apparatus for locating center of reference pulse in a measurement system

  • US 4,628,469 A
  • Filed: 10/17/1984
  • Issued: 12/09/1986
  • Est. Priority Date: 09/29/1982
  • Status: Expired due to Term
First Claim
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1. In a method for determining spatial coordinates of a workpiece, the steps comprising:

  • (a) illuminating said workpiece with a planar source of light;

    (b) electronically viewing the intersections of the planar source of light and said workpiece from a known location spaced apart from said workpiece;

    (c) scanning electronic images formed by said electronic viewing along a plurality of scan lines, in which the scanning of each line produces a reference pulse corresponding to the location at which the planar light intersects said workpiece;

    (d) determining the centroid of the reference pulse on at least one of said scan lines by the substeps of;

    (i) sampling a pulse signal representing said reference pulse;

    (ii) digitizing said samples to generate digital values representative of the magnitude of said pulse samples;

    (iii) performing a first integration by sequentially adding said digital values to produce a first sum signal;

    (iv) performing a second integration by adding intermediate sums associated with said substep of sequentially adding said digital values to produce a second sum signal; and

    (v) dividing said second sum signal by said first sum signal to produce an offset distance representing an offset distance by which the centroid of said pulse signal precedes the location at which the last sample of said pulse signal was taken; and

    (e) calculating the spatial coordinates of said point on the workpiece using the centroid of said reference pulse and said known location of said step of electronic viewing.

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