Magnetometer Calibration Inside Generator Coils
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Solution Overview
Problem
Current magnetometer calibration methods are either too restrictive, requiring placement in remote areas free from magnetic disturbances or necessitate complex and precise calibration of Helmholtz coils, which can be bulky and interfere with measurements, especially when calibrating objects with limited space.
Innovation Solution
A method involving a magnetometer placed inside a magnetic field generator with multiple windings, where the magnetic field is generated by applying electric current, and the magnetometer's position and current variations are measured to calculate calibration parameters using an optimization algorithm, allowing for simultaneous calibration of the magnetometer and magnetic field model without prior calibration of the generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the free-field method is used to calibrate magnetometers by placing them in remote areas free from magnetic disturbances, then measurement accuracy is improved, but the ease of operation deteriorates due to the restrictive requirement of remote placement
Solution Approach 1:
The patent introduces Helmholtz coils as an intermediary device that generates a controlled magnetic field to replace the need for remote natural environments. The coils act as a mediator between the magnetometer and the magnetic field source, allowing calibration to be performed in a controlled laboratory setting rather than requiring travel to remote locations free from magnetic disturbances.
Solution Approach 2:
The patent changes the parameter of magnetic field source from natural environmental fields (requiring remote locations) to artificially generated fields via Helmholtz coils. By controlling the current through the coils, the magnetic field strength and characteristics can be precisely adjusted, enabling accurate calibration without the restrictive location requirements of the free-field method.
2Measurement precision
If Helmholtz coils are used to generate a homogeneous magnetic field for calibration, then measurement precision is improved, but device complexity increases due to the requirement of precise coil calibration
Solution Approach 1:
The patent merges the calibration of the magnetometer with the characterization of the Helmholtz coils into a single simultaneous process. Instead of separately calibrating the coils with a standard magnetometer and then using them to calibrate other magnetometers, the method jointly determines the calibration parameters of multiple magnetometers while simultaneously characterizing the magnetic field generated by the coils, thereby reducing overall complexity.
Solution Approach 2:
The patent enables the Helmholtz coils to serve themselves by using the measurements from the magnetometers to automatically characterize the magnetic field generated by the coils. The system uses the magnetometer readings to back-calculate the actual magnetic field conditions, eliminating the need for separate, complex manual calibration of the coils with high-precision reference instruments.
3Measurement precision
If the magnetometer is placed inside the Helmholtz coils for calibration, then calibration accuracy is improved, but the volume available for the object to be calibrated decreases due to the bulky coil structure
Solution Approach 1:
The patent employs dynamic positioning of the magnetometer within the Helmholtz coils during calibration. By moving the magnetometer to multiple known positions inside the coil assembly and performing measurements at each position, the method captures the three-dimensional magnetic field characteristics. This dynamic approach allows accurate calibration without requiring excessive static space, as the same physical volume is utilized from multiple spatial perspectives.
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 simplifies magnetometer calibration by determining directional factors, biases, and location, enabling precise calibration without the need for remote placement and reducing the complexity of coil calibration, thus improving calibration accuracy and efficiency.
Implementation Method 1
generate a magnetic field in the generator by applying an electric current to each winding
Implementation Method 2
measuring the magnetic field generated in the generator with the at least one magnetometer
Data Source
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AI summary
The present invention relates to a method for calibrating a magnetometer (3), wherein the magnetometer (3) is arranged inside the coils (21) of a generator (2), a magnetic field being generated by the generator (2), a series of measurements of the magnetic field with the magnetometer (3) being achieved by varying the position of the magnetometer (3) and/or the electric currents in the coils (21) between each measurement, the electric currents used in the coils (21) also being measured, a parametric transfer model being generated from a parametric measurement model of the magnetometer comprising calibration parameters of the magnetometer and a parametric model of the magnetic field, the calibration parameters of the magnetometer (3) being calculated by an optimisation algorithm from the parametric transfer model and magnetic field measurements provided by the magnetometer and the measurement of currents in the coils.