Magnetic Field Sensor Compensation for Stray Field Gradient Errors
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Solution Overview
Problem
Magnetic field sensors arranged non-symmetrically relative to magnetized metal bodies are influenced by external magnetic stray fields, leading to inaccurate measurements due to magnetic field gradients, particularly in scenarios where limited space requires sensors to be positioned outside the magnetic balance or in configurations with multiple ferromagnetic components.
Innovation Solution
The use of at least two magnetic field sensors with differing sensitivities, where one sensor is positioned closer to the magnetic field antenna to detect and compensate for external magnetic stray fields by deflecting and concentrating magnetic field lines, thereby reducing the influence of magnetic field gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If magnetic field sensors are arranged non-symmetrically outside the magnetic balance area to save space, then space requirements are reduced, but measurement accuracy deteriorates due to external magnetic stray fields and magnetic field gradients
Solution Approach 1:
The system is divided into two functional segments: at least two magnetic field sensors with different sensitivities work together to separate the measurement of the magnetic field gradient (for compensation) from the measurement of the actual magnetic field signal. This segmentation allows accurate measurements even in non-symmetric positions outside the magnetic balance area.
Solution Approach 2:
The evaluation device calculates a compensation value based on the difference between signals from the two sensors with different sensitivities, and uses this compensation value to correct the measurement data. This feedback mechanism continuously eliminates the influence of external magnetic stray fields and magnetic field gradients, maintaining measurement accuracy in space-constrained non-symmetric installations.
2Use of energy by moving object
If magnetic field sensors are positioned closer to the magnetized body to improve signal strength, then reception strength is improved, but sensitivity to external magnetic stray fields increases
Solution Approach 1:
The two magnetic field sensors are designed with different local qualities in terms of sensitivity. One sensor has higher sensitivity to detect weak magnetic field gradients for compensation, while the other has appropriate sensitivity for measuring the main magnetic field signal. This differential local quality allows the system to simultaneously achieve strong signal reception and compensation for stray field interference.
Solution Approach 2:
The sensor with different sensitivity acts as an intermediary that detects the magnetic field gradient caused by external stray fields. Its signal serves as a mediator that enables the evaluation device to calculate compensation values, thereby indirectly protecting the main measurement from stray field interference while allowing close positioning for strong signal reception.
3Adaptability or versatility
If multiple ferromagnetic components are used in the system, then functional versatility is improved, but magnetic field gradient influence worsens due to additional magnetic field deflection and concentration
Solution Approach 1:
The measurement system is segmented into multiple sensors with different sensitivities, each contributing to different aspects of the measurement. This segmentation enables the system to handle complex magnetic field environments created by multiple ferromagnetic components by separating the gradient detection function from the main signal detection function.
Solution Approach 2:
The evaluation device continuously calculates compensation values based on the differential signals from the two sensors and applies these corrections to the measurement data. This feedback mechanism dynamically compensates for the additional magnetic field gradient influences introduced by multiple ferromagnetic components, maintaining measurement accuracy despite increased system complexity and versatility.
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 allows for accurate detection and evaluation of stress-based magnetic fields by compensating for external magnetic stray fields and gradients, ensuring reliable measurements across various installation circumstances without the need for additional apparatus.
Implementation Method 1
The magnetic field sensor measures the action of the torque acting on the shaft on the magnetic field
Implementation Method 2
external magnetic stray fields, which are deflected/concentrated due to the asymmetrical alignment of magnetized or non-magnetized metal bodies in relation to the sensor
Data Source
AI summary
A device compensates for the an influence of a magnetic field gradient which may be generated due to a component geometry of a component (1). The device includes at least two magnetic field sensors (17, 18) which are arranged outside of the magnetic balance of the ferromagnetic component (1). The at least two magnetic field sensors (17, 18) each have a differing sensitivity. One of the magnetic field sensors (17, 18) is exposed to the influence of the magnetic field gradient to a greater extent compared to the other magnetic field sensor due to its spatial arrangement relative to the ferromagnetic component (1). The one magnetic field sensor may have a sensitivity lower than the other magnetic field sensor.