Single gyro northfinder
First Claim
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1. A northfinding apparatus comprising:
- a platform having a sensor component mounting surface, and associated with said platform is a fixed orthogonal coordinate system defined by X, Y, and Z reference axes, and said Z axis being aligned substantially with vertical relative to the earth'"'"'s surface;
angular rate sensing means secured to said platform, said angular rate sensing means having an input axis aligned substantially with said X axis for providing an output signal R representative of the rotation rate sensed about said input axis;
tilt indicating means, secured to said platform, for providing an output signal representative of the angle of tilt Tx of said platform from true horizontal relative to the center of the earth and about said Y-axis;
tilt rate indicating means, secured to said platform, for providing an output signal S representative of the rate of tilt of said platform about said X-axis;
means for computing the azimuth angle AZ of said platform representative of the angle between said X-axis and the direction of true north as a function of said output signals representative of tilt angle Tx, tilt rate S, and angular rotation rate R, and the earth'"'"'s latitude at which said platform is positioned, and the earth'"'"'s rotation rate.
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Abstract
Disclosed is a northfinding apparatus having a single rotation rate sensor secured to a platform. The output of the rotation rate sensor is corrected for tilt and tilt rate of the platform. Measurements of the tilt and tilt rate and the rotation rate are combined to provide an azimuth angle of the platform relative to north.
126 Citations
5 Claims
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1. A northfinding apparatus comprising:
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a platform having a sensor component mounting surface, and associated with said platform is a fixed orthogonal coordinate system defined by X, Y, and Z reference axes, and said Z axis being aligned substantially with vertical relative to the earth'"'"'s surface; angular rate sensing means secured to said platform, said angular rate sensing means having an input axis aligned substantially with said X axis for providing an output signal R representative of the rotation rate sensed about said input axis; tilt indicating means, secured to said platform, for providing an output signal representative of the angle of tilt Tx of said platform from true horizontal relative to the center of the earth and about said Y-axis; tilt rate indicating means, secured to said platform, for providing an output signal S representative of the rate of tilt of said platform about said X-axis; means for computing the azimuth angle AZ of said platform representative of the angle between said X-axis and the direction of true north as a function of said output signals representative of tilt angle Tx, tilt rate S, and angular rotation rate R, and the earth'"'"'s latitude at which said platform is positioned, and the earth'"'"'s rotation rate. - View Dependent Claims (2, 3, 4, 5)
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Specification