Magnetic Position Sensor Gradient Signal Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic position sensor systems face challenges in achieving a balance between large measurement range and high accuracy while being robust against external disturbance fields and demagnetization, often requiring complex processing and significant resources.
Innovation Solution
A position sensor device with a semiconductor substrate and multiple sensors measuring in-plane and out-of-plane magnetic field components, using gradient calculations to generate both coarse and fine signals, which are processed using basic arithmetic operations to determine position without requiring advanced processors or resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex processing methods (such as DFT or FFT) are used to achieve high measurement precision, then measurement accuracy is improved, but device complexity and processing resource requirements increase
Solution Approach 1:
The patent replaces complex signal processing algorithms (DFT/FFT) with a simplified mathematical approach based on gradient calculations and arctangent functions. Instead of using digital signal processors with multiply-accumulate instructions, the system uses basic arithmetic operations (addition, subtraction, multiplication, division) and look-up tables that can be executed on simple microcontrollers, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent transforms the position determination problem by changing the mathematical parameters from frequency-domain analysis (DFT/FFT) to spatial gradient-based calculation. The system calculates magnetic field gradients in x and z directions and uses arctangent functions to determine position, which simplifies the computational requirements while preserving measurement accuracy.
2Device complexity
If simple arithmetic operations are used to reduce processing complexity, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent performs preliminary calculations of magnetic field gradients and stores pre-computed values in look-up tables. By pre-calculating gradient values and arctangent relationships, the system enables simple microcontrollers to achieve accurate position determination using basic arithmetic operations without requiring complex real-time processing.
Solution Approach 2:
The patent uses look-up tables that store pre-computed gradient and position relationship data. Instead of performing complex real-time calculations, the system copies pre-determined values from tables based on measured gradient inputs, thereby achieving high measurement precision with simple processing hardware.
3Loss of information
If magnetic field measurements are taken to determine position, then position information is obtained, but sensitivity to external disturbance fields increases
Solution Approach 1:
The patent replaces direct magnetic field magnitude measurements with gradient-based measurements. By calculating spatial derivatives of the magnetic field components (dBx/dx and dBz/dx) and using their ratio in arctangent functions, the system determines position while becoming insensitive to constant external disturbance fields, as gradients cancel out uniform field additions.
4Ease of manufacture
If permanent magnets are used to generate the magnetic field, then the magnetic structure is simple, but robustness against demagnetization is reduced
Solution Approach 1:
The patent replaces direct dependence on permanent magnet field strength with gradient-based measurements. Since the position determination relies on the ratio of gradients (dBx/dx)/(dBz/dx) rather than absolute field values, the system becomes insensitive to demagnetization effects. Even if the permanent magnet loses some strength, the gradient ratios remain consistent, preserving measurement 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
The solution enables accurate position determination over a large range with robustness against external disturbances and demagnetization, using simple processing that is insensitive to external fields and does not require complex calculations or resources.
Implementation Method 1
at least three sensors (S1, S2, S3) for measuring at least three first magnetic field components (Bx1, Bx2, Bx3), oriented in a first direction (X) substantially parallel to the substrate
Data Source
AI summary
A position sensor system for determining a position of a sensor device relative to a magnetic structure, the system comprising: said magnetic structure comprising a plurality of non-equidistant poles; said sensor device comprising at least three magnetic sensors spaced apart over predefined distances; and the sensor device being adapted for: a) measuring at least three in-plane magnetic field components, and for calculating two in-plane field gradients therefrom; b) measuring at least three out-of-plane magnetic field components, and for calculating two out-of-plane field gradients therefrom; c) calculating a coarse signal based on these gradients; d) calculating a fine signal based on these gradients; e) determining said position based on the coarse signal and the fine signal.