Inertial Measurement Unit Heading Stabilization via Periodic Rotation
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Solution Overview
Problem
Inexpensive inertial navigation systems relying on platform relative horizontal position change or velocity references often fail to correct heading drift, leading to large position errors and potential off-course navigation of airborne vehicles.
Innovation Solution
A method and system that utilize a rotational device to periodically rotate an inertial measurement unit between two orientations, allowing horizontal and vertical sensing elements to be calibrated using horizontal aiding measurements, enabling the Kalman filter to correct navigation solutions and estimate heading drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inertial navigation system uses only platform relative horizontal position change or velocity references, then the system remains inexpensive and simple, but heading drift cannot be corrected leading to large position errors
Solution Approach 1:
The patent applies the dynamics principle by periodically rotating the inertial measurement unit between two orientations about a horizontal axis. This dynamic reorientation allows the vertical sensing elements to be calibrated using horizontal aiding measurements at different times, enabling heading drift correction without adding complex hardware. The rotation transforms the static limitation into a dynamic calibration opportunity.
Solution Approach 2:
The patent implements periodic action through regular rotation of the inertial measurement unit between two orientations. This periodic reorientation creates opportunities to calibrate vertical sensing elements using horizontal references, systematically correcting heading drift over time. The periodic nature allows the system to maintain accuracy without continuous complex interventions.
2Ease of operation
If the gyroscope is oriented perpendicular to the tangential plane with constant altitude, then the system structure is simplified, but heading drift cannot be observed for correction
Solution Approach 1:
By dynamically rotating the inertial measurement unit between two orientations, the system temporarily changes the orientation of sensing elements relative to the horizontal reference plane. This allows vertical sensing elements to assume horizontal orientations during rotation, enabling them to be calibrated using horizontal aiding measurements. The dynamic reorientation resolves the contradiction between simple operation and accurate measurement.
3Productivity
If heading drift is not corrected, then the system operates continuously without interruption, but position errors accumulate over time causing the vehicle to go off course
Solution Approach 1:
The patent applies preliminary action by periodically calibrating the vertical sensing elements before significant heading drift accumulates. Through regular rotation and calibration using horizontal aiding measurements, the system proactively corrects potential heading errors. This preventive calibration approach maintains position accuracy over time without interrupting overall navigation operations.
Data Source
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AI summary
A method of stabilizing heading in an inertial navigation system is provided. The method includes operating an inertial measurement unit comprising horizontal-sensing elements and off-horizontal-scnsing 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.