Borehole inertial guidance system
First Claim
1. A borehole survey apparatus comprising:
- a borehole probe for insertion in a borehole;
control means for controlling the movement of said probe in the borehole;
means for generating a signal representative of the angular rotation of the earth;
acceleration means secured within said probe for generating three acceleration signals representing the components of acceleration of said probe with respect to three axes;
first angular means secured within said probe for generating two rotation signals representing the angular rotation of said probe with respect to two axes of rotation;
means responsive to said acceleration signals for generating when said probe is moving a first synthetic angular rotation signal representing the angular rotation of said probe about a third axis of rotation different from said two axes of rotation;
means responsive to said signal representative of the angular rotation of the earth for generating when said probe is not moving a second synthetic angular rotation signal representing the angular rotation of said probe about said third axis of rotation;
transform means responsive to said rotation signals and at least one of said first and second synthetic rotation signals, said transform means including means for providing a transformation signal for transforming signals representing probe movement in a probe referenced coordinate system to an earth referenced coordinate system; and
first computation means operatively connected to said transform means and acceleration means for converting said acceleration signals into a first set of velocity signals representing the velocity of said probe.
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Accused Products
Abstract
In order to improve the accuracy of borehole survey systems utilizing probes with inertial components including inclinometers, two ring laser gyro units are included to provide rotation information to the system. When the probe is moving in a borehole, inclinometer iformation is used to produce a synthetic rotation signal to take the piece of a third gyro and the earth'"'"'s rotation is used for a similar purpose in combination with signals from the two ring laser gyros when the probe is stopped. Wire line velocity is used in combination with the inclinometer and gyro information to provide signals representing the probe velocity and position. Coordinate transformations are provided in the probe to transform the inertial signals and wire line velocity signals into earth reference coordinate system. Kalman filtering incorporates noninertial velocity data to reduce the effect of errors inherent in the generation of various input signals to the system.
61 Citations
30 Claims
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1. A borehole survey apparatus comprising:
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a borehole probe for insertion in a borehole; control means for controlling the movement of said probe in the borehole; means for generating a signal representative of the angular rotation of the earth; acceleration means secured within said probe for generating three acceleration signals representing the components of acceleration of said probe with respect to three axes; first angular means secured within said probe for generating two rotation signals representing the angular rotation of said probe with respect to two axes of rotation; means responsive to said acceleration signals for generating when said probe is moving a first synthetic angular rotation signal representing the angular rotation of said probe about a third axis of rotation different from said two axes of rotation; means responsive to said signal representative of the angular rotation of the earth for generating when said probe is not moving a second synthetic angular rotation signal representing the angular rotation of said probe about said third axis of rotation; transform means responsive to said rotation signals and at least one of said first and second synthetic rotation signals, said transform means including means for providing a transformation signal for transforming signals representing probe movement in a probe referenced coordinate system to an earth referenced coordinate system; and first computation means operatively connected to said transform means and acceleration means for converting said acceleration signals into a first set of velocity signals representing the velocity of said probe. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification