Magnetic Position Sensor Gain Calibration via Feedback Coils
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic position sensors face challenges in achieving high accuracy due to gain mismatches among magnetic field sensors, which can lead to incomplete cancellation of stray magnetic fields and increased angular error drift.
Innovation Solution
The implementation of a magnetic position sensor device with multiple magnetic field sensor units and one or more coils, where the coils generate calibration magnetic fields to extract gain factors and correct for gain errors, thereby mitigating sensitivity mismatch and drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple magnetic field sensor units are used to improve measurement precision, then gain mismatches and sensor sensitivity variations increase, leading to incomplete stray field cancellation and increased angular error drift
Solution Approach 1:
The patent implements a feedback mechanism where sensor output signals are fed back to the coil windings to generate calibration magnetic fields. This feedback loop enables continuous adjustment and compensation of gain mismatches among sensor units, allowing the system to maintain high measurement precision while correcting sensitivity variations through iterative calibration processes.
Solution Approach 2:
The patent changes the magnetic field parameters by generating calibration magnetic fields through coil windings that are activated in response to sensor outputs. By dynamically adjusting these calibration fields based on measured sensor signals, the system compensates for gain mismatches and maintains consistent performance across multiple sensor units, resolving the contradiction between using multiple sensors and maintaining gain match consistency.
2Measurement precision
If calibration magnetic fields are generated using coil windings to correct gain errors, then position sensing accuracy improves, but device complexity increases due to additional calibration circuitry and control mechanisms
Solution Approach 1:
The patent makes the coil windings serve multiple functions: they act as both magnetic field generation elements for position sensing and as calibration elements for correcting gain errors. By using the same physical components (coils) for both purposes, the system achieves high measurement precision through calibration while minimizing the increase in device complexity, as no separate dedicated calibration hardware is required.
Solution Approach 2:
The calibration system is self-service in nature, where the sensor outputs themselves trigger the calibration process. The sensor signals are used to generate the calibration magnetic fields through the coil windings, and the system automatically adjusts without requiring external calibration equipment or complex control mechanisms. This self-calibration approach improves accuracy while keeping the added complexity to a minimum.
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 solution enhances the accuracy of position sensing by effectively mitigating gain errors and achieving stray field immunity, meeting stringent requirements such as <0.5 degree angular error drift and immunity to 5 mT DC fields.
Implementation Method 1
one or more coils having one or more footprints overlapping the first and second magnetic field sensor units... providing a calibration current to one or more coils... receiving a first sensor signal from the first magnetic field sensor unit, the first sensor signal representing one or more calibration magnetic fields provided by the one or more coils responsive to the calibration current
Implementation Method 2
using hall-effect sensors. Hall-effect sensors are configured to measure magnetic fields and produce an output voltage representative of the sensed field
Data Source
AI summary
In a described example, a position sensor can include a first magnetic field sensor unit having a first sensor output, a second magnet field sensor unit having a second sensor output, one or more coils having one or more footprints overlapping the first and second magnetic field sensor units, and a processing circuit having a first sensor input, a second sensor input, a current terminal, and a sensing output, the first sensor input coupled to the first sensor output, the second sensor input coupled to the second sensor output, and the current terminal coupled to the one or more coils.