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Calibration of ship attitude reference

  • US 7,451,022 B1
  • Filed: 12/28/2006
  • Issued: 11/11/2008
  • Est. Priority Date: 12/28/2006
  • Status: Expired due to Fees
First Claim
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1. A method for calibration of an attitude reference apparatus, said method comprising the steps of:

  • providing an inertial navigation system for a surface ship, which navigation system provides local reference of the ship'"'"'s attitude relative to East, North, and UP;

    providing a star tracker mounted on a platform stabilized by said local reference of the ship'"'"'s attitude, said star tracker being for comparing the azimuth and elevation angles between the line-of-sight of said star tracker and each of two selected stars, to thereby generate first and second azimuth and elevation differences;

    controlling said line-of-sight of said star tracker in response to ephemeris of said two selected stars;

    processing said azimuth and elevation angles to determine first and second vector triads representing ephemeris and the navigation system attitude;

    processing said first and second triads to determine a coordinate transformation matrix;

    separating said coordinate transformation matrix into systematic error and reference attitude error; and

    combining the reference attitude error with the navigation system attitude to generate calibrated navigation system attitude.

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