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Apparatus and method for controlling a moving vehicle utilizing a digital differential analysis circuit

  • US 5,379,353 A
  • Filed: 09/22/1993
  • Issued: 01/03/1995
  • Est. Priority Date: 05/09/1988
  • Status: Expired due to Fees
First Claim
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1. A device for detecting a boundary of a roadway upon which a vehicle travels, the device comprising:

  • camera means for generating electronic signals representing an image of the roadway, the image comprising a view of the roadway extending in a direction of travel of the vehicle;

    a signal inputting unit for digitizing the signals representing the image of the roadway;

    an edge detecting unit for processing the digitized signals to produce edged picture element signals differentiated with respect to pixel to pixel brightness variations;

    a preprocessing unit for receiving the edged picture element signals from the edge detecting unit and storing in a multivalue memory circuit edged picture data corresponding to the edged picture element signals, the edged picture data corresponding to each edged picture element signal comprising an address in an X-Y coordinate system and an edged brightness value;

    digital differential analysis computing means including a plurality of digital differential analysis computing circuits which are serially connected, each for converting the addresses of the edged picture data from the X-Y coordinate system to an α



    coordinate system and computing a rotary motion recurrence formula to generate a plurality of approximate HOUGH curves in a ρ



    coordinate system, the approximate HOUGH curves intersecting at a plurality of points in the ρ



    coordinate system, and said rotary motion recurrence formula comprising the equation
    
    
    space="preserve" listing-type="equation">α

    .sub.i+1 =α

    .sub.i -2.sup.-m β

    .sub.i ;

    and
    
    
    space="preserve" listing-type="equation">β

    .sub.i+1 =2.sup.-m α

    .sub.i+1 +β

    .sub.iwherein an angle of rotation comprises
    
    
    space="preserve" listing-type="equation">ε

    =2.sup.-m (rad) (m=0, 1, 2, . . . );

    a histogram memory circuit for storing address data corresponding to the intersection points between the generated approximate HOUGH curves; and

    a processor for generating a signal representing the boundary of the roadway based on the stored address data corresponding to the intersection points of the approximate HOUGH curves.

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