Instrument alignment devices and methods
First Claim
1. An apparatus for determining an instrument boresight heading, comprising:
- an instrument having a boresight;
an elevation positioner for positioning the elevation of the instrument boresight having an elevation axis;
an azimuth positioner for positioning the azimuth of the instrument boresight having an azimuth axis; and
a sensor including a gyro having a sensitive axis;
wherein the azimuth of the instrument boresight relative to true north is determined from an output of the gyro obtained at a plurality of different positions of the azimuth positioner and the instrument boresight is aligned relative to true north.
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Accused Products
Abstract
An apparatus and method, for determining an instrument boresight heading. The apparatus comprises an instrument having a boresight, an elevation positioner for positioning the elevation of the instrument boresight having an elevation axis, an azimuth positioner for positioning the azimuth of the instrument boresight having an azimuth axis and a sensor including a gyro having a sensitive axis. The method comprises recording a first output of a gyro of an azimuth positioner having an instrument boresight azimuth heading in a first position, rotating the azimuth positioner to a second position, recording a second output of the gyro and rotating the azimuth positioner to a third position, recording a third output of the gyro and determining the azimuth heading relative to true north from the first, second and third output.
25 Citations
18 Claims
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1. An apparatus for determining an instrument boresight heading, comprising:
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an instrument having a boresight;
an elevation positioner for positioning the elevation of the instrument boresight having an elevation axis;
an azimuth positioner for positioning the azimuth of the instrument boresight having an azimuth axis; and
a sensor including a gyro having a sensitive axis;
wherein the azimuth of the instrument boresight relative to true north is determined from an output of the gyro obtained at a plurality of different positions of the azimuth positioner and the instrument boresight is aligned relative to true north. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining an instrument boresight azimuth heading, comprising:
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recording a first output of a gyro of an azimuth positioner having an instrument boresight azimuth heading in a first position;
rotating the azimuth positioner to a second position;
recording a second output of the gyro;
rotating the azimuth positioner to a third position;
recording a third output of the gyro;
determining the azimuth heading relative to true north from the first, second and third output; and
aligning the azimuth heading of the instrument boresight relative to true north. - View Dependent Claims (9, 10, 11)
where y1 is the first output, y2 is the second output and y3 is the third output.
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12. A method of determining a local vertical, comprising:
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recording a first output of an accelerometer of an azimuth gimbal having an instrument boresight azimuth heading in a first position;
rotating the azimuth positioner to a second position;
adjusting a first tilt angle of the azimuth positioner until a second output of the accelerometer is substantially equivalent to the first output;
rotating the azimuth positioner to a third position; and
adjusting a second tilt angle of the azimuth positioner until a third output of the is substantially equal to the first output. - View Dependent Claims (13, 14)
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15. A boresight alignment device, comprising:
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a turntable rotatable at a rotation rate including;
an accelerometer having a first output; and
a gyro having a second output;
wherein the accelerometer and the gyro are substantially co-aligned with an in-plane axis of the turntable;
an index pulse generator for sensing the rotation rate;
a phase lock loop controller communicatively coupled to the index pulse generator and having a third output and a fourth output out of phase by a phase offset and fifth output; and
a motor for turning the turntable having a motor driver driven by the fifth output;
wherein the first output and the third output are combined to produce a gravity vector position and the second output and the fourth output are combined to produce an Earth rotation vector position. - View Dependent Claims (16, 17, 18)
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Specification