Sensor Assembly Magnetization Direction Determination
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Solution Overview
Problem
Existing linear position measurement systems using Hall sensors with permanent magnets face limitations in measurement range and accuracy due to temperature influences and magnetization scattering, as well as inefficient utilization of magnetic field components, leading to restricted travel ranges and sensitivity to external spurious influences.
Innovation Solution
A sensor assembly comprising two magnetic field sensors spaced apart to detect magnetic field components in different spatial directions, with a processing means to combine these components and determine the magnetization direction based on their magnitudes and signs, enabling a four-quadrant evaluation method that enlarges the usable travel range and enhances robustness against external influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the linear range of Z components of the magnetic field is used for position determination, then the implementation is simple, but the measurement accuracy is strongly influenced by magnet temperature and production-induced magnetization scattering
Solution Approach 1:
The patent changes the evaluation parameters from using absolute magnetic field component values to using ratios of magnetic field components (Bx/Bz) and their arctan calculations. This parameter transformation makes the position determination independent of magnet temperature and magnetization strength, thereby resolving the contradiction between implementation simplicity and measurement precision.
Solution Approach 2:
The patent combines multiple magnetic field components (Bx and Bz) into a composite evaluation method using ratio calculation and arctan functions. This composite approach leverages the complementary information from different field components to achieve temperature-independent position determination while maintaining implementation feasibility.
2Ease of manufacture
If the linear range method is used, then implementation is easy, but the usable travel range of the permanent magnet is relatively small
Solution Approach 1:
The patent transforms the position evaluation from direct linear range measurement to ratio-based arctan calculation, which naturally extends the measurable range. The arctan(Bx/Bz) function provides continuous position information over a much larger travel range, resolving the contradiction between implementation simplicity and travel range.
3Measurement precision
If the ratio of two magnetic field components is used for position determination, then temperature independence is achieved, but the travel range is limited by the evaluation method rather than field component height
Solution Approach 1:
The patent utilizes both X and Z dimensional magnetic field components simultaneously in a four-quadrant evaluation scheme. By considering the signs and magnitudes of both Bx and Bz components, the system achieves temperature independence while extending the travel range to utilize the full theoretical capability of the magnetic field measurements.
4Device complexity
If conventional Hall sensor evaluation is used, then the system is simple, but the detection range and magnetic field components are not utilized fully
Solution Approach 1:
The patent makes the sensor system universal by implementing a four-quadrant evaluation method that correctly determines position regardless of the magnet's magnetization direction. This multi-functional approach allows the same sensor assembly to work with magnets magnetized in any direction, fully utilizing the detection capabilities without increasing physical 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 solution effectively enlarges the practical measurement range and increases the system's robustness by accurately determining the magnetization direction and position, while being independent of temperature and other spurious influences, thus improving the overall performance of the position measurement system.
Implementation Method 1
a first magnetic field sensor for detecting a first magnetic field component with respect to a first spatial direction and a second magnetic field component with respect to a second spatial direction
Data Source
AI summary
A sensor assembly for determining a magnetization direction of an indicator magnet with respect to the sensor assembly includes a first magnetic field sensor for detecting a first and a second magnetic field component with respect to a first and a second spatial direction, and a second magnetic field sensor for detecting a third and a fourth magnetic field component with respect to the second spatial direction, wherein the first and the second magnetic field sensor are spaced apart from one another. Further, the sensor assembly includes a processor that is implemented to combine the first and the second magnetic field component to obtain a first combination quantity, to combine the third and the fourth magnetic field component to obtain a second combination quantity, to determine a position of the indicator magnet and the magnetization direction.