Magnetic Sensor Error Estimation Using GNSS Geomagnetism
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Solution Overview
Problem
Existing methods for calculating sensor errors in magnetic sensors installed on movable bodies, such as ships, are either time-consuming or incomplete, leading to inaccurate azimuth calculations.
Innovation Solution
A device and method that includes a GNSS attitude angle calculating module, a GNSS geomagnetism calculating module, and an error estimating module to accurately estimate sensitivity, misalignment, and bias errors of a magnetic sensor using GNSS positioning signals and magnetic detection values, allowing for precise correction of magnetic detection values and subsequent accurate azimuth calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ship makes a full turn to calculate sensor error, then the error can be calculated, but it requires a lot of time
Solution Approach 1:
The system pre-calculates and stores geomagnetic field values at multiple predetermined azimuths (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) before actual azimuth measurement. This preliminary action allows the system to compare pre-stored values with real-time magnetic sensor readings without requiring time-consuming full turns or complex real-time calculations, thus resolving the contradiction between measurement precision and time consumption.
2Loss of time
If only partial error components are calculated, then the calculation is faster, but the error cannot be calculated accurately
Solution Approach 1:
The magnetic sensor error is segmented into three distinct components: sensitivity error, misalignment error, and bias error. Each component is calculated separately using specific formulas and pre-stored geomagnetic data. This segmentation allows the system to comprehensively correct all error sources without requiring time-consuming full-turn procedures, thus resolving the contradiction between calculation speed and accuracy.
Solution Approach 2:
The system changes the approach from calculating errors during dynamic movement (full turn) to calculating errors by comparing pre-stored geomagnetic parameters at multiple fixed azimuths with real-time sensor readings. This parameter change enables accurate multi-component error calculation without time loss.
3Ease of operation
If standard geomagnetism data from external sources is used, then the calculation can be performed, but it requires additional external data sources and complexity
Solution Approach 1:
The system uses the magnetic sensor itself to detect and correct its own errors by comparing readings with pre-stored geomagnetic field values. This self-service approach eliminates the need for external calibration equipment or complex external data sources, reducing system complexity while maintaining ease of operation.
Data Source
AI summary
The purpose is to accurately and promptly calculate an error of a magnetic sensor. A sensor error calculating device may include a GNSS attitude angle calculating module, a GNSS geomagnetism calculating module, and an error estimating module. The GNSS attitude angle calculating module may calculate a GNSS attitude angle of a movable body based on positioning signals of a GNSS. The GNSS geomagnetism calculating module may calculate a GNSS geomagnetism based on the GNSS attitude angle. The error estimating module may estimate a sensitivity error, a misalignment error and a bias error of the magnetic sensor by using a magnetic detection value of the magnetic sensor and the GNSS geomagnetism.