In-drilling alignment
First Claim
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1. An apparatus for inertial navigation, comprising:
- a piston contained within a cylinder;
an inertial measurement unit;
in which the inertial measurement unit is connected to the piston so that motion of the piston causes motion of the inertial measurement unit along an axis; and
in which the inertial measurement unit or a data collecting device receiving data from the inertial measurement unit is configured to use measurements taken by the inertial measurement unit of the motion of the inertial measurement unit along the axis to correct or compensate for errors in the alignment of the inertial measurement unit.
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Abstract
To limit the growth of errors of an inertial navigation system for measurement-while-drilling, in-drilling alignment methods can be used. A pneumatics-based design of an apparatus for an in-drilling alignment method and its implementation downhole are described.
29 Citations
20 Claims
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1. An apparatus for inertial navigation, comprising:
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a piston contained within a cylinder; an inertial measurement unit; in which the inertial measurement unit is connected to the piston so that motion of the piston causes motion of the inertial measurement unit along an axis; and in which the inertial measurement unit or a data collecting device receiving data from the inertial measurement unit is configured to use measurements taken by the inertial measurement unit of the motion of the inertial measurement unit along the axis to correct or compensate for errors in the alignment of the inertial measurement unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for inertial navigation, comprising:
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a capsule; an inertial measurement unit within the capsule; a linear drive for the inertial measurement unit; a rotary drive for the inertial measurement unit; in which the inertial measurement unit is connected to the linear drive so that the linear drive causes motion of the inertial measurement unit in relation to the capsule along a linear axis; and in which the inertial measurement unit is connected to the rotary drive so that the rotary drive causes rotation of the inertial measurement unit around a rotary axis; and in which the inertial measurement unit or a data collecting device receiving data from the inertial measurement unit is configured to use measurements taken by the inertial measurement unit of the motion of the inertial measurement unit along the linear axis and the rotation of the inertial measurement unit around the rotary axis to correct or compensate for errors in the alignment of the inertial measurement unit. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method for correcting alignment errors in an inertial navigation system, comprising the steps of:
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moving an inertial measurement unit along a linear axis within a capsule containing the inertial measurement unit while simultaneously rotating the inertial measurement unit around a rotary axis; using the inertial measurement unit to take a measurement of the motion and rotation; comparing the measurement of the motion and rotation to an expected measurement of the motion and rotation; and using the difference between the measurement and the expected measurement to correct alignment errors. - View Dependent Claims (17, 18)
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19. A method of correcting or compensating for alignment errors in an inertial navigation system, comprising the steps of:
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moving an inertial measurement unit along an axis within a capsule during a time period; using a magnetostrictive sensor to measure the position of the inertial measurement unit at plural times during the time period; using the inertial measurement unit to measure acceleration during the time period; comparing the measurements of the position by the magnetostrictive sensor to the measurements of the acceleration by the inertial measurement unit to estimate errors in the alignment of the inertial measurement unit; and using the estimates of the errors in the alignment of the inertial measurement unit to correct or compensate for the errors. - View Dependent Claims (20)
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Specification