Offaxis Insensitive Multipole Magnet Sensor System
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Solution Overview
Problem
Existing sensor systems for angular position measurement are not robust enough against position errors and mechanical drift over time, especially in the presence of vibrations, which affects their accuracy and reliability.
Innovation Solution
A sensor system utilizing a multi-pole ring magnet with a mechanical or magnetic periodic feature, such as grooves or protrusions, to generate a rotationally symmetric multipole magnetic field, reducing spatial inhomogeneities and enhancing robustness against position errors and mechanical drift without requiring additional processing power or energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sensor systems are used for angular position measurement, then the system structure is simple, but the system is not robust against position errors and mechanical drift over time
Solution Approach 1:
The patent applies local quality by introducing grooves or protrusions at specific locations on the magnet surface. These localized structural modifications create regions with different magnetic field characteristics, specifically generating a rotationally symmetric multipole magnetic field with enhanced uniformity in the central region, thereby improving robustness against position errors without requiring complete restructuring of the entire magnet
Solution Approach 2:
The patent utilizes asymmetry by creating grooves or protrusions that break the perfect rotational symmetry of the magnet surface. This controlled asymmetry generates higher-order magnetic field components that, when combined with the basic dipole field, create a multipole field configuration that is more insensitive to off-axis positioning errors and mechanical drift
2Measurement precision
If conventional magnets without periodic features are used, then the manufacturing is simpler, but the magnetic field has spatial inhomogeneities that reduce measurement accuracy
Solution Approach 1:
The patent applies segmentation by dividing the magnet surface into distinct regions separated by grooves or protrusions. This segmentation creates multiple magnetic pole regions with controlled spatial distribution, generating a multipole magnetic field pattern that provides more uniform field gradients in the measurement region, thereby improving angular position measurement accuracy
Solution Approach 2:
The patent implements periodic action by arranging grooves or protrusions in a rotationally symmetric periodic pattern around the magnet circumference. This periodic structural modulation creates corresponding periodic variations in the magnetic field that generate a multipole field configuration, improving field uniformity and measurement precision while maintaining manufacturability through repetitive manufacturing processes
3Reliability
If standard multipole magnets are used, then the system is compact, but position errors occur due to spatial inhomogeneities in the magnetic field
Solution Approach 1:
The patent applies parameter changes by modifying the physical geometry of the magnet surface through grooves or protrusions. These geometric parameter modifications alter the magnetic field distribution parameters, specifically creating a multipole field configuration with enhanced uniformity and reduced spatial inhomogeneities, thereby improving robustness against position errors while maintaining system compactness
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 solution significantly improves the sensor system's robustness and accuracy by maintaining performance over the lifetime, even with mechanical wear and vibrations, by ensuring a more uniform magnetic field gradient, thereby reducing position errors and harmonics in measured signals.
Implementation Method 1
a multi-pole ring magnet with a number N (e.g. N being at least 4) of pole pairs that are axially magnetized to generate an N-pole magnetic field
Implementation Method 2
The grooves and/or protrusions are arranged in a rotationally symmetric pattern around said axis, and are shaped and sized so as to provide a substantially constant magnetic field gradient in a central region around said axis
Implementation Method 3
The sensor device is adapted for measuring or determining at least one magnetic field component and/or at least one magnetic field (spatial) gradient component
Data Source
AI summary
A sensor system comprises a magnetic field generator and a sensor device arranged at a distance from said magnetic field generator and adapted for measuring or determining at least one magnetic field component and/or at least one magnetic field gradient component. The magnetic field generator comprises a multi-pole magnet having a number N of pole pairs that are axially magnetized to generate an N-pole magnetic field that is substantially rotationally symmetric around an axis. The magnet comprises a plurality of grooves and/or elongate protrusions that are arranged in a rotationally symmetric pattern around the axis to provide a substantially constant magnetic field gradient in a central region around said axis.