Heading stabilization for aided inertial navigation systems
First Claim
1. A method of stabilizing heading in an inertial navigation system, the method comprising:
- operating an inertial measurement unit comprising horizontal-sensing elements and off-horizontal-sensing elements, while the inertial measurement unit is in a first orientation, wherein the horizontal-sensing elements are oriented in a horizontal reference plane;
calibrating the horizontal-sensing elements of the inertial measurement unit based on horizontal aiding measurements;
forward-rotating the inertial measurement unit by a selected-rotation angle about a horizontal-rotation axis, wherein the inertial measurement unit is oriented in a second orientation, and wherein, while the inertial measurement unit is in the second orientation, the off-horizontal-sensing elements are oriented in the horizontal reference plane;
operating the forward-rotated inertial measurement unit while the inertial measurement unit is in the second orientation; and
calibrating the rotated off-horizontal-sensing elements based on horizontal aiding measurements while the inertial measurement unit is in the second orientation.
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Accused Products
Abstract
A method of stabilizing heading in an inertial navigation system includes operating an inertial measurement unit comprising horizontal-sensing elements and off-horizontal-sensing elements while the inertial measurement unit is in a first orientation, calibrating the horizontal-sensing elements of the inertial measurement unit based on horizontal aiding measurements, forward-rotating the inertial measurement unit by a selected-rotation angle about a horizontal-rotation axis so that the inertial measurement unit is oriented in a second orientation, operating the forward-rotated inertial measurement unit while the inertial measurement unit is in the second orientation, and calibrating the rotated off-horizontal-sensing elements based on horizontal aiding measurements while the inertial measurement unit is in the second orientation. When the inertial measurement unit is in the first orientation, the horizontal-sensing elements are oriented in a horizontal reference plane. When the inertial measurement unit is in the second orientation, the off-horizontal-sensing elements are oriented in the horizontal reference plane.
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Citations
20 Claims
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1. A method of stabilizing heading in an inertial navigation system, the method comprising:
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operating an inertial measurement unit comprising horizontal-sensing elements and off-horizontal-sensing elements, while the inertial measurement unit is in a first orientation, wherein the horizontal-sensing elements are oriented in a horizontal reference plane; calibrating the horizontal-sensing elements of the inertial measurement unit based on horizontal aiding measurements; forward-rotating the inertial measurement unit by a selected-rotation angle about a horizontal-rotation axis, wherein the inertial measurement unit is oriented in a second orientation, and wherein, while the inertial measurement unit is in the second orientation, the off-horizontal-sensing elements are oriented in the horizontal reference plane; operating the forward-rotated inertial measurement unit while the inertial measurement unit is in the second orientation; and calibrating the rotated off-horizontal-sensing elements based on horizontal aiding measurements while the inertial measurement unit is in the second orientation. - View Dependent Claims (2, 3, 4)
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5. A method of stabilizing heading in an inertial navigation system, the method comprising:
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operating an inertial measurement unit in an un-rotated orientation; calibrating at least one horizontal-sensing gyroscope and at least one horizontal-sensing accelerometer based on horizontal aiding measurements received while operating the inertial measurement unit in the un-rotated orientation; forward-rotating the inertial measurement unit about a horizontal-rotation axis, the horizontal-rotation axis being orthogonal to the direction sensed by at least one horizontal-sensing gyroscope; operating the inertial measurement unit in a rotated orientation; and calibrating a vertical gyroscope and a vertical-sensing accelerometer based on horizontal aiding measurements received while operating the inertial measurement unit in the rotated orientation. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. An inertial navigation system, comprising:
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an inertial measurement unit; rotational device on which the inertial measurement unit is positioned, the rotational device configured to rotate the inertial measurement unit about a horizontal axis from a first orientation to a second orientation; a software module comprising; a navigation module configured to receive input from the inertial measurement unit; a Kalman filter communicatively coupled to the navigation module; a software control component configured to control the rotation of the rotational device based on input received from the Kalman filter; and at least one of a velocity sensor and a position sensor operable to measure a velocity and a position, respectively, and further operable to output the information indicative of a velocity and a position to the Kalman filter, respectively; and a navigation processor for running the software module; wherein the Kalman filter is configured to calibrate the inertial measurement unit in the first orientation and the second orientation and to correct output from the navigation module based on estimates of a bias in the inertial measurement unit. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification