Angular Position Sensor Device With Magnetic Field Component Extraction
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Solution Overview
Problem
Magnetic sensor systems face challenges in accurately determining angular position with robustness against cross-talk, external disturbance fields, and long-term drift, often requiring trade-offs between competing requirements such as accuracy, robustness, and cost-effectiveness.
Innovation Solution
The proposed solution involves an angular position sensor system using a cylindrical magnet and a sensor device with multiple magnetic sensitive elements, where the sensor is positioned to minimize cross-talk and external disturbance by measuring specific magnetic field components, and utilizing an integrated magnetic concentrator structure with horizontally arranged Hall elements to enhance accuracy and reduce drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor device measures all three magnetic field components (Bx, By, Bz) using conventional sensor configurations, then the measurement covers a complete magnetic field space, but cross-talk between different magnetic field components occurs and measurement accuracy deteriorates
Solution Approach 1:
The patent extracts and eliminates the harmful By component from the measurement system by positioning the sensor at a specific location where the By component is negligible (smaller than 20% of Bx). This allows the sensor to measure only Bx and Bz components, removing the source of cross-talk while maintaining measurement completeness for the relevant angular position parameters.
Solution Approach 2:
The patent applies local quality by selecting a specific local position for the sensor device where the magnetic field has particular characteristics (By component is minimal). This localized positioning creates optimal measurement conditions at that specific location, allowing accurate measurement of Bx and Bz without interference from the By component.
2Measurement precision
If the sensor device is positioned close to the magnet to improve measurement sensitivity, then the signal strength increases, but sensitivity to external disturbance fields increases
Solution Approach 1:
The patent converts the potential harm of external disturbance fields into a benefit by using the specific positioning where the By component is naturally minimal. This positioning creates a measurement environment that is inherently resistant to external disturbances affecting the By component, while still maintaining strong Bx and Bz signals for accurate angular position measurement.
3Device complexity
If conventional sensor configurations are used to measure magnetic field components, then the sensor structure is simple, but robustness against long-term drift caused by mechanical stress variations is poor
Solution Approach 1:
The patent implements feedback by measuring both Bx and Bz components and using their ratio to calculate angular position. This feedback mechanism automatically compensates for long-term drift and mechanical stress variations, as the ratio of the two components remains stable even when individual component measurements are affected by drift, thereby maintaining measurement accuracy over time.
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 configuration improves the accuracy and robustness of angular position determination by reducing cross-talk and sensitivity to external disturbances, while maintaining robustness against long-term drift, thereby providing a more reliable and precise measurement.
Implementation Method 1
a permanent magnet for generating a magnetic field
Implementation Method 2
magnetic sensitive elements configured for measuring at least a first magnetic field component (e.g. Bx1) oriented in a first direction (e.g. X) and a second magnetic field component (e.g. By1; Bz1) oriented in a second direction (e.g. Y; Z) perpendicular to the first direction
Data Source
AI summary
Angular position sensor system comprising: a cylindrical magnet rotatable about a rotation axis; and an angular position sensor device comprising: a substrate comprising a plurality of magnetic sensitive elements configured for measuring a first magnetic field component in a first direction and a second magnetic field component in a second direction perpendicular to the first direction; and a processing circuit configured for calculating the angular position; the sensor device being oriented such that the first direction is oriented in a circumferential direction, and the second direction is either parallel or orthogonal to the rotation axis; the sensor device being located at a predefined position where a magnitude of a third magnetic field component orthogonal to the first and second magnetic field component is negligible over the 360° angular range.