Magnetic Sensor Calibration Tool With Orthogonal Field Generation
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Solution Overview
Problem
Achieving perfect parallelism between magnetic sensor sensitivity vectors and reference axes for accurate magnetic field measurements is challenging due to difficulties in aligning the direction of the magnetic field vector, leading to insufficient calibration accuracy.
Innovation Solution
A calibration tool with a cuboid-shaped housing and multiple permanent magnets, arranged to provide a stable, constant magnetic field with orthogonal components, allowing for precise alignment and temperature-independent field intensity, enabling the production of perfectly orthogonal magnetic field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Helmholtz coils or electromagnets are used as magnetic field source, then a stable homogeneous magnetic field can be produced, but the direction alignment with sensor axes is difficult to achieve perfectly
Solution Approach 1:
The patent changes the fundamental parameter of magnetic field generation from electromagnetic (requiring power and complex alignment) to permanent magnets (providing intrinsic stable field). The permanent magnets are positioned at specific locations (e.g., corners or faces of a cube) with predetermined orientations, creating orthogonal magnetic field components that automatically align with the sensor axes, eliminating the alignment difficulty while maintaining field stability.
2Reliability
If permanent magnets are used to generate magnetic field, then temperature stability can be achieved, but field homogeneity and orthogonality are difficult to maintain
Solution Approach 1:
The patent divides the magnetic field generation into multiple independent permanent magnets positioned at specific locations (e.g., four magnets at alternate corners of a cube, or magnets on each face). Each magnet contributes to one or more orthogonal field components. This segmentation allows the field to be constructed from simpler, more controllable units, making it easier to achieve both homogeneity and orthogonality while maintaining temperature stability.
Solution Approach 2:
The patent uses composite arrangements of permanent magnets with different orientations and positions to create a composite magnetic field. By combining fields from multiple magnets with specific magnetization directions (e.g., alternating N-S pole orientations), the system achieves both field homogeneity in the working volume and precise orthogonality of field components, while the permanent magnet materials provide inherent temperature stability.
3Measurement precision
If multiple permanent magnets are arranged to provide orthogonal magnetic field components, then calibration accuracy is improved, but device complexity increases
Solution Approach 1:
The patent designs the permanent magnet arrangement to serve multiple functions simultaneously: the same set of magnets generates all three orthogonal magnetic field components (Bx, By, Bz), provides field homogeneity in the working volume, and establishes the coordinate system alignment. For example, four magnets at alternate corners of a cube can generate all three field components through their combined magnetic fields, eliminating the need for separate magnet sets for each axis and reducing overall device 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
The calibration tool ensures high accuracy in magnetic field measurements by providing a stable, temperature-independent magnetic field with orthogonal components, overcoming the limitations of existing calibration methods.
Implementation Method 1
The one or more permanent magnets provide in a working volume a magnetic field that has a constant field intensity
Implementation Method 2
the positions of the permanent magnets along the axis are selected such that the temperature coefficient of the sum of the intensities of the magnetic field and the additional magnetic field in the working volume is zero
Data Source
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AI summary
A calibration tool (1) for calibrating a magnetic sensor comprises a cuboid-shaped housing (2) and one or more magnets (3, 4). The housing (2) is configured to provide six alignment planes. The alignment planes lying opposite to each other extend parallel to each other and the alignment planes lying adjacent to each other include an angle of 90°. The housing (2) has one or more holes (8) allowing to position a magnetic sensor in a working volume located in the center of the housing (2). The housing (2) may have six sidewalls. One or more of the sidewalls may include one or more adjustable element protruding from the respective sidewall. The adjustable elements may be screws. Magnets of different materials having different temperature coefficients may be used to eliminate the temperature dependence of the magnetic field in the working volume.