Survey apparatus and method employing rate-of-turn and free gyroscopes
First Claim
1. In apparatus for determining azimuth, the combination that comprises(a) a rate-of-turn gyroscope including a first rotor having a spin axis,(b) support means to support the gyroscope for lengthwise travel along another axis and to rotate about said other axis,(c) said gyroscope having first means for producing an output which varies as a function of azimuth orientation of the gyroscope relative to the earth'"'"'s spin axis, and(d) a free gyroscope operatively carried for movement along said other axis with said rate-of-turn gyroscope, said free gyroscope including a second rotor having a spin axis subject to re-orientation,(e) said free gyroscope also having means for producing an output which varies as a function of azimuth orientation of the free gyroscope,(f) other means responsive to the output of the rate-of-turn gyroscope to effect said re-orientation of the free gyroscope spin axis,(g) control means connected with said other means to periodically cause said other means to effect said alignment, while said travel is effectively interrupted, and(h) said support means supporting both gyroscopes for travel in a bore hole.
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Abstract
Survey apparatus and method employs a free gyroscope for fast determination of azimuth, free gyroscope alignment being periodically corrected by a rate gyroscope which is periodically rotated for accurate azimuth determination. An accelerometer is also usable in conjunction with the gyroscopes for tilt determination. More generally, method and means is provided for calibrating (initially or periodically) an angle or position reference device.
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Citations
33 Claims
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1. In apparatus for determining azimuth, the combination that comprises
(a) a rate-of-turn gyroscope including a first rotor having a spin axis, (b) support means to support the gyroscope for lengthwise travel along another axis and to rotate about said other axis, (c) said gyroscope having first means for producing an output which varies as a function of azimuth orientation of the gyroscope relative to the earth'"'"'s spin axis, and (d) a free gyroscope operatively carried for movement along said other axis with said rate-of-turn gyroscope, said free gyroscope including a second rotor having a spin axis subject to re-orientation, (e) said free gyroscope also having means for producing an output which varies as a function of azimuth orientation of the free gyroscope, (f) other means responsive to the output of the rate-of-turn gyroscope to effect said re-orientation of the free gyroscope spin axis, (g) control means connected with said other means to periodically cause said other means to effect said alignment, while said travel is effectively interrupted, and (h) said support means supporting both gyroscopes for travel in a bore hole.
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17. In a survey method which employs instrumentation embodying both rate-of-turn and free gyroscopes, the steps that include
(a) traveling both said gyroscopes together along a travel direction, (b) operating the free gyroscope to produce an output indicative of azimuth orientation of the instrumentation, and (c) operating the rate-of-turn gyroscope to produce an output which is indicative of azimuth orientation of the instrumentation, (d) periodically using the output of the rate-of-turn gyroscope to re-orient the free gyroscope, while said traveling of both gyroscopes along said direction is substantially interrupted. (e) and employing a cable to suspend said gyroscopes for said travel in a bore hole.
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20. In apparatus for determining azimuth, the combination comprising
(a) an angle reference device carried for movement along a travel axis in a bore hole, said device having a calibratable component, (b) first means for measuring angular rate and having output for effecting calibration of said component, and (c) control means operatively connected with said first means to cause said first means to periodically effect said callibration of said component.
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30. In a survey method which employs an angle reference device and first means for measuring angular rate and having an output for effecting calibration of said device, the steps that include
(a) traveling both said device and first means together along a travel direction in a bore hole; -
(b) operating said device to produce an output indicative of azimuth orientation; and (c) periodically using said output of said first means to calibrate said device, while said traveling is substantially interrupted.
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31. In apparatus for determining azimuth, the combination that comprises
(a) a rate-of-turn sensor, (b) support means to support the sensor for lengthwise travel along a travel axis, (c) said sensor having first means for producing an output which varies as a function of azimuth orientation of the sensor relative to the earth'"'"'s spin axis, and (d) a free gyroscope operatively carried for movement along said travel axis with said sensor, said free gyroscope including a calibratable component, (e) said free gyroscope also having means for producing an output which varies as a function of azimuth orientation of the free gyroscope, (f) other means responsive to the output of the sensor to effect said calibration of the free gyroscope, (g) control means connected with said other means to periodically cause said other means to effect said calibration, (h) said support means supporting said sensor and said free gyroscope for travel in a bore hole.
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32. In apparatus for determining azimuth, the combination that comprises
(a) a rate-of-turn gyroscope including a first rotor having a spin axis, (b) support means to support the gyroscope for lengthwise travel along another axis and to rotate about said other axis, (c) said gyroscope having first means for producing an output which varies as a function of azimuth orientation of the gyroscope relative to the earth'"'"'s spin axis, and (d) a free gyroscope operatively carried for movement along said other axis with said rate-of-turn gyroscope, said free gyroscope including a calibratable component, (e) said free gyroscope also having means for producing an output which varies as a function of azimuth orientation of the free gyroscope, (f) other means responsive to the output of the rate-of-turn gyroscope to effect said calibration of the free gyroscope, (g) control means connected with said other means to periodically cause said other means to effect said calibration, and (h) said support means supporting both gyroscopes for travel in a bore hole.
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33. In a survey method which employs instrumentation including a rate-of-turn sensor and a calibratable free gyroscope, the steps that include
(a) traveling said sensor and said gyroscope together along a travel direction, (b) operating the free gyroscope to produce an output indicative of azimuth orientation of the instrumentation, and (c) operating the sensor to produce an output which is indicative of azimuth orientation of the instrumentation, and (d) periodically using the output of the sensor to calibrate the free gyroscope, at different locations along said travel direction, (e) and employing a cable to suspend said sensor and said gyroscope for said travel in a bore hole.
Specification