Magnetometer Calibration Using Roll and Turn Data
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Solution Overview
Problem
Current marine surveying techniques face challenges in accurately calibrating compasses used in towed objects due to magnetic dip angles, leading to significant errors in heading readings, especially in areas with high magnetic dip angles.
Innovation Solution
A method involving the acquisition of roll and turn data from magnetometers and accelerometers during multiple orientations and turns, followed by calibration to correct for deviations, effectively compensating for mounting angle offsets and improving compass accuracy across different magnetic dip angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional magnetometer calibration is performed without considering magnetic dip angles, then the calibration process is simple, but the compass accuracy deteriorates significantly in areas with high magnetic dip angles
Solution Approach 1:
The patent performs preliminary calibration actions by acquiring roll data at multiple headings and turn data before final calibration. This preliminary data collection enables the system to pre-calculate correction parameters that compensate for magnetic dip effects, thereby improving compass accuracy without increasing the complexity of the actual calibration operation.
Solution Approach 2:
The patent introduces a new dimension to calibration by incorporating turn data in addition to roll data. By utilizing data from rotational movements in multiple dimensions (rolls at different headings plus turns), the system creates a more comprehensive calibration dataset that accounts for magnetic dip angles, thereby improving accuracy without significantly complicating the process.
2Measurement precision
If calibration is performed using only roll data, then the calibration process is faster, but the accuracy deteriorates in areas with high magnetic dip angles
Solution Approach 1:
The patent merges roll data acquisition with turn data acquisition into a unified calibration process. By combining these two types of data collection, the system achieves comprehensive calibration that accounts for magnetic dip angles while minimizing additional time requirements, as the turn data can be collected during normal operational movements rather than requiring separate dedicated calibration maneuvers.
Solution Approach 2:
The system performs calibration using data that is naturally generated during normal towed object operations. Turn data is collected during routine heading changes that occur during survey operations, eliminating the need for separate time-consuming calibration maneuvers. This self-service approach maintains accuracy while minimizing time loss.
3Reliability
If magnetometer calibration is performed without turn data, then the calibration process is simpler, but the reliability of heading readings deteriorates in areas with high magnetic dip angles
Solution Approach 1:
The patent changes the calibration parameters by incorporating turn rate and heading change data in addition to traditional roll data. This parameter expansion enables the calibration algorithm to model and compensate for magnetic dip effects more accurately, thereby improving heading reading reliability. The increased parameter complexity is managed through automated processing that minimizes the perceived procedural complexity for operators.
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 significantly enhances the accuracy of compass readings, reducing errors by up to 10 degrees and providing reliable navigational data even in areas with high magnetic dip angles, thereby improving the quality of marine survey data.
Implementation Method 1
acquiring roll data from a magnetometer and an accelerometer of a towed object telemetry unit coupled to a towed object during a plurality of rolls
Implementation Method 2
acquiring roll data from a magnetometer and an accelerometer of a towed object telemetry unit coupled to a towed object during a plurality of rolls
Data Source
AI summary
Roll data can be acquired from a magnetometer and an accelerometer of a towed object telemetry unit coupled to a towed object during rolls of the towed object in two or more different headings. The magnetometer can be calibrated based on the roll data. Turn data can be acquired from the magnetometer and the accelerometer during a turn of the towed object from a first heading to a second heading. The magnetometer can be further calibrated based on the turn data.