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Non-contact sensor with particular utility for measurement of road profile

  • US 4,786,815 A
  • Filed: 02/12/1987
  • Issued: 11/22/1988
  • Est. Priority Date: 02/12/1987
  • Status: Expired due to Fees
First Claim
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1. Apparatus for measuring distance to a surface comprising first means for directing a light beam onto said surface;

  • second means including optically sensitive position detection means, and means for receiving light reflected by said surface and directing said reflected light onto said detection means, said detection means providing a pair of signal A and B as a function of orthogonal position coordinates of such reflected light incident on said detection means;

    means for providing a signal A-B as a function of a difference between said signals A and B;

    means for providing a signal A+B as a function of a sum of said signals A and B;

    means for indicating distance to the surface as a function of a ratio P of said difference signal A-B to said sum signal A+B;

    means mounting said first and second means to establish a frame of reference spaced by a nominal distance H from the surface, said apparatus being constructed to measure departure X of the surface from said nominal distance H within a measurement window W, said first and second means being separated by said mounting means by a distance L; and

    means for determining said distance X as a function of the equation;

    X=(P*K1)/(K2+P*K3), where K1 is a constant equal to (L2 +H2)1/2, K2 is a constant equal to F sin(a), K3 is a constant equal to cos(a), a is angle of orientation between said first and second means at said nominal distance H, and F equals image distance.

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