Magnetic Field Sensor Calibration via Oblique Coordinate Transformation
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Solution Overview
Problem
Existing methods for calibrating multiaxial magnetic field sensors are cumbersome, requiring elaborate rotations or complex analysis, leading to prolonged measurement times and uncertain accuracy due to transverse sensitivities and manufacturing tolerances.
Innovation Solution
A method involving exposure to at least three linearly independent magnetic fields with known vectors, allowing for the creation of a transformation matrix to translate sensitivity vectors into an orthogonal coordinate system, enabling precise calibration of sensitivity and transverse sensitivity without the need for orthogonal magnetic fields or mechanical rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If elaborate rotations of the magnetic field sensor or generation of orthogonal magnetic fields are used for calibration, then calibration completeness (sensitivity and transverse sensitivity) is improved, but measurement time increases significantly (up to several hours)
Solution Approach 1:
The patent changes the calibration approach from using orthogonal magnetic fields requiring mechanical rotations to using at least three linearly independent magnetic fields with arbitrary orientations. This parameter change in the magnetic field configuration allows determination of all sensitivity coefficients through mathematical analysis without mechanical rotation, reducing calibration time from hours to minutes while maintaining complete calibration accuracy.
Solution Approach 2:
The patent replaces the mechanical rotation system (physically rotating the sensor or generating orthogonal fields through mechanical means) with a mathematical transformation system. By using at least three linearly independent magnetic fields and applying matrix mathematics to the measurement data, the patent eliminates the need for mechanical rotations while achieving complete calibration of sensitivity and transverse sensitivity coefficients.
2Measurement precision
If orthogonal magnetic fields and elaborate rotations are used for calibration, then complete calibration is achieved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical rotation systems and orthogonal field generation apparatus with a simplified system using at least three linearly independent magnetic fields of arbitrary orientation. The complexity is shifted from mechanical hardware to mathematical processing, where matrix operations on measurement data from the simpler field configuration yield complete calibration results.
Solution Approach 2:
The patent creates a universal calibration method that works with magnetic fields of arbitrary orientation rather than requiring specific orthogonal configurations. This universal approach using at least three linearly independent fields can be implemented with simpler magnetic field sources (such as permanent magnets or simple coil arrangements) that generate fields in any orientation, making the calibration system more versatile and less complex.
3Ease of manufacture
If complex analysis based on optimisation and fit algorithms is used, then calibration can be performed, but the accuracy of calibration cannot be conclusively determined
Solution Approach 1:
The patent replaces iterative optimization and fit algorithms with direct mathematical transformation using matrix operations. By using at least three linearly independent magnetic fields, the calibration equations become a solvable linear system that can be directly transformed into an orthogonal coordinate system through matrix mathematics, providing exact solutions rather than approximate fitted results and enabling conclusive accuracy verification.
Solution Approach 2:
The patent creates a mathematical model (transformation matrix) that exactly copies and transforms the measurement data from the oblique coordinate system of arbitrary magnetic fields into the orthogonal coordinate system. This direct mathematical copying and transformation approach preserves measurement accuracy without the distortions introduced by iterative optimization algorithms, allowing conclusive verification of calibration accuracy.
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 allows for rapid and accurate calibration of monoaxial or multiaxial magnetic field sensors, eliminating the need for complex rotations and lengthy measurement times, while ensuring the accuracy of calibration parameters and correcting sensor axis orientations.
Implementation Method 1
magnetic field sensor is exposed consecutively to at least three magnetic fields having different magnetic field vectors
Data Source
AI summary
In a method for calibrating the sensitivity of a monoaxial or multiaxial magnetic field sensor, the magnetic field sensor is exposed consecutively to at least three magnetic fields having different magnetic field vectors which may be freely orientated in space so that they span an oblique coordinate system. The magnetic fields are measured with the magnetic field sensor in order to obtain a sensitivity vector in the oblique coordinate system of the magnetic field vectors for each sensor axis. The sensitivity vectors are transformed into an orthogonal coordinate system via a transformation matrix, and sensitivity and transverse sensitivity of each sensor axis are then calculated on the basis of the transformed sensitivity vectors either directly or following a further transformation. The method enables rapid, precise calibration of all sensitivities of a magnetic field sensor, since it does not require any orthogonal magnetic fields.