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Primary land arctic navigation system

  • US 5,075,693 A
  • Filed: 10/05/1989
  • Issued: 12/24/1991
  • Est. Priority Date: 10/05/1988
  • Status: Expired due to Fees
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Assignment
First Claim
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1. A land navigation system for use in a vehicle, comprising, in combination:

  • a plurality of sensors including;

    a magnetometer for providing a first output signal representative of the heading of said vehicle;

    a speed sensor for providing an output signal representative of the speed of said vehicle, said speed sensor being an odometer type of sensor operable to convert vehicle odometer cable rotation into electrical pulses;

    a gyrocompass for providing a second heading output signal and vehicle dynamic pitch and roll attitude output signals, said gyrocompass being capable of dual mode operation including a gyrocompass mode operable when said vehicle is stationary whereby to provide an initial heading output signal and a directional gyro mode operable when said vehicle is in motion;

    a baroaltimeter for providing an output signal representative of the altitude of said vehicle above a predetermined datum;

    receiver means for receiving satellite position transmissions and providing an output signal representative of the position of said vehicle, said receiver means including a single channel C/A code satellite receiver and a dual channel transit satellite receiver; and

    control means, including a microprocessor, arranged to receive the output of each said plurality of sensors and provide a continuous optimal estimate of position, altitude and heading of said vehicle, said control means including;

    display means for displaying the optimal estimate of position, altitude and heading of said vehicle, said display means including a first display monitor for displaying position, heading a desired heading information on a continuous basis and a central display for displaying time, position, heading, speed and desired heading on a continuous basis;

    means connected to each said sensors for obtaining said output signals at predetermined timed intervals, converting said output signals to a digital form to produce digitized output signals, said obtaining means including means for monitoring the output of said receiver means and transmitting receiver output signals to said obtaining means;

    means responsive to said digitized output signals for pre-filtering said digitized output signals to produce pre-filtered digitized output signals and delivering said pre-filtered digitized output signals to said display means and a Kalman filtering means, said means responsive to digitized output signals being further operable to integrate said heading and speed output signals over a predetermined period of time and compute therefrom, and the initial position of said vehicle at the beginning of said predetermined period of time, the current heading, speed and position of said vehicle;

    Kalman filtering means responsive to said pre-filtered digitized output signals for determining errors in said prefiltered digitized output signals and producing and delivering corrected pre-filtered digitized output signals to a memory means, said display means and said means responsive to digitized output signals;

    operator input means for enabling an operator to enter commands and data required or requested by said system into said system; and

    memory means for storing said output signals, said memory means including an elevation map referable by said Kalman filtering means for use in determining and bounding any error in said output signal representative of the altitude of said vehicle and a geo-magnetic field model referable by said Kalman filtering means for use in determining an error in said second output signal representative of the heading of said vehicle and an output signal representative of the attitude of said vehicle.

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