Magnetic Field Sensor Sensitivity Adaptation via Differential Ratios

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Solution Overview

Problem

The increasing demand for efficient and cost-effective magnetic field sensor solutions in vehicles, particularly e-bikes, is challenged by the need for robust measurement methods amidst weight reduction and cost pressure, with existing sensors requiring tight sensitivity tolerances and being prone to interference.

Innovation Solution

A method that adjusts magnetic field sensor sensitivities by using three sensors with aligned measuring axes to detect signals, allowing for minimal error compensation of interference fields, and compensates for differential sensitivity drifts without interrupting operations, using a signal conductor to guide signals through the sensors and adjust measured variables based on detected differences and ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If tight sensitivity tolerances are required for magnetic field sensors, then measurement accuracy is improved, but manufacturing cost increases and device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent changes the evaluation parameter from absolute sensitivity values to differential sensitivity ratios. By evaluating the ratio between sensitivities of different magnetic field sensors rather than requiring each sensor to meet strict absolute tolerance specifications, the system allows for broader manufacturing tolerances while maintaining measurement accuracy through post-manufacturing adaptation.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If tight sensitivity tolerances are required for magnetic field sensors, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs self-calibration by automatically determining adaptation values based on differential measurements between sensors. The control unit calculates sensitivity ratios and computes adaptation values that compensate for sensitivity mismatches, allowing the system to self-correct without requiring external calibration equipment or complex manual adjustment procedures.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If sensitivity adaptation is performed, then tolerance requirements are relaxed, but measurement operation is interrupted

Engineering Contradiction:
Improvetolerance requirementsVSAvoidmeasurement operation continuity
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent implements periodic sensitivity adaptation at predetermined intervals during normal operation. The control unit periodically determines current sensitivity values, calculates updated adaptation values, and applies corrections without requiring extended shutdown periods. This periodic approach allows the system to maintain accuracy while minimizing disruption to measurement operations.

Inventive Principle:
Principle #19Periodic action

4Reliability

If sensitivity drift compensation is implemented, then measurement reliability over time is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement reliability over timeVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system implements feedback-based drift compensation by continuously monitoring sensitivity changes over time and temperature. The control unit determines sensitivity values at different operating conditions, calculates adaptation values to compensate for detected drift, and applies corrections to maintain measurement accuracy. This feedback mechanism automatically compensates for aging and environmental effects without requiring complex additional hardware.

Inventive Principle:
Principle #23Feedback

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 approach reduces the demands on sensor sensitivity, lowers costs, and maintains accuracy over time and temperature ranges, ensuring reliable and efficient magnetic field measurements without high tolerance requirements.

Implementation Method 1

detecting the first signal by means of a first measurement by a first magnetic field sensor with a first measuring axis, a second magnetic field sensor with a second measuring axis and a third magnetic field sensor with a third measuring axis

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4414731A1Method for adapting at least one measurement variable of a magnetic field sensor
Publication Date: 2024.08.14 ROBERT BOSCH GMBH
  • EP4414731A1 patent drawingFigure 1
  • EP4414731A1 patent drawingFigure 2~3
  • EP4414731A1 patent drawingFigure 4

AI summary

The present invention relates to a method (100) for adjusting at least one measured quantity of a magnetic field sensor, comprising the steps of generating (S1) a first signal in a signal conductor (14), acquiring (S2) the first signal by means of a first measurement by a first magnetic field sensor (18) with a first measuring axis (28), a second magnetic field sensor (20) with a second measuring axis (32) and a third magnetic field sensor (22) with a third measuring axis (36), wherein the first measuring axis (28), the second measuring axis (32) and the third measuring axis (36) have substantially the same orientation (38), generating (S3) a second signal in the signal conductor (14), acquiring (S4) the second signal by means of a second measurement by the first magnetic field sensor (18), the second magnetic field sensor (20) and the third magnetic field sensor (22), acquiring (S5) the at least one measured quantity by means of the first magnetic field sensor (18),of the second magnetic field sensor (20) and the third magnetic field sensor (22), adjusting (S6) the at least one detected measured quantity based on the detected first signal and the detected second signal.