Inertial Sensor Drift Compensation for Orientation Alignment
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Solution Overview
Problem
Existing methods for determining relative orientation between two different locations, such as boresighting systems, face challenges with accuracy due to drift in inertial orientation sensors and the effects of earth rotation, which can introduce errors in orientation measurements.
Innovation Solution
A device and method utilizing an inertial orientation sensor coupled with an imager and a processor to determine the relative orientation between two locations by accounting for sensor drift and earth rotation, employing orientation indicators like BRUs or arrays of light emitters, and compensating for scaling errors through image analysis and gyroscopic integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inertial orientation sensors are used for boresighting, then the ability to determine relative orientation between different locations is improved, but sensor drift and earth rotation effects introduce measurement errors
Solution Approach 1:
The system performs preliminary calibration by measuring the orientation of the inertial sensor at multiple known positions (first, second, and third positions) before actual boresighting operations. These preliminary measurements establish reference data that is used to calculate and compensate for sensor drift and earth rotation effects during subsequent measurements, thereby improving reliability without sacrificing measurement precision
Solution Approach 2:
The system implements a feedback mechanism where the measured orientation data from multiple positions is processed to determine drift characteristics, and this drift information is then fed back to correct subsequent orientation measurements. The processor continuously refines the drift model based on repeated measurements at known positions, enabling real-time compensation that maintains both precision and reliability
2Measurement precision
If multiple orientation measurements are taken at different positions and times, then sensor drift can be determined and compensated, but the complexity of the boresighting process increases
Solution Approach 1:
The inertial sensor system is designed to perform multiple functions: it serves as both the primary boresighting instrument and the drift sensing device. The same sensor that measures orientation for alignment purposes also detects drift when positioned at known locations, eliminating the need for separate calibration equipment and simplifying the overall system while maintaining high measurement precision
Solution Approach 2:
The boresighting process is segmented into distinct phases: calibration phase where the sensor is positioned at predetermined locations to measure drift, and measurement phase where the sensor performs actual boresighting. This segmentation allows the complex task of drift compensation to be separated from the primary alignment function, making each phase more manageable and reducing overall process complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of relative orientation determination by correcting for sensor drift and earth rotation effects, improving the precision of alignment between different coordinate systems.
Implementation Method 1
an inertial orientation sensor that measures orientation information
Implementation Method 2
an imager that captures images of the orientation indicator
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
A device for determining relative orientation between two locations including an imager, an inertial-orientation-sensor firmly attached to the imager for determining information relating to the orientation thereof and which exhibits drift and a processor coupled with the Imager and with the inertial-orientation-sensor. The processor determines a first orientation-measurement and first time-tag when the' device is oriented with a first-orientation-indicator located at a first location. The processor determines a second-orientation-measurement and second time-tag when the device is oriented with a second-orientation-indicator located at a second location. The processor determines a third-orientation-measurement and third time-tag when the device is oriented again with the flrst-orientation-indicator. The processor determines the drift associated the inertial-orientation-sensor according to difference between the first-orientatlon-measurernent and the third-orientation-rneasurement the respective time-tags associated therewith. The processor determines an angle-difference between the first-orientation-indicator and the second-orientation-indicator according to the first-orientation-measurenient and the second-orientation-measurernent, the first and second time-tags and the drift.