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Apparatus for automatic guidance of a trackless vehicle

  • US 4,258,813 A
  • Filed: 11/20/1978
  • Issued: 03/31/1981
  • Est. Priority Date: 11/22/1977
  • Status: Expired due to Term
First Claim
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1. An apparatus for guiding a trackless vehicle along a path defined by a guide cable disposed in the road surfce, said guide cable carrying an alternating current, thereby generating an alternating electromagnetic field in the space surrounding the guide cable, said apparatus having detector means for detecting the direction and magnitude of the alternating magnetic field, said detector means including a first detecting coil (13) disposed substantially horizontally on said vehicle and a second detecting coil (14) disposed substantially perpendicular to said first detecting coil, for generating from the alternating magnetic field first and second alternating signals, respectively,and comprising, in accordance with the invention,phase shifting means (24) connected to the second detecting coil (14) and receiving the second signal to shift the phase of said second signal and thereby form a third signal;

  • and computer means (21, 22;

         25) connected to the first coil for receiving said first signal and to the phase shifting means (24) for receiving the third signal,said computer means includingclock means (25t;

    31, 25t'"'"') andcomparator means (21,

         22) comparing the relative phase of the first signal representative of the phase of the alternating magnetic field with the phase of the third signal,said computer deriving a digital error signal as a function of the phase difference between the first and third signals to thereby obtain a control signal to steer said vehicle in the sense of reducing the phase difference between the first and third signals, resulting in guiding said vehicle (10) in a path over said guide cable (12).

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