Rotation Angle Measurement Linearization Using Harmonic Error Feedback

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Solution Overview

Problem

Existing sensor devices for measuring rotation angles often suffer from nonlinearities and errors due to factors like sensor inaccuracies, temperature drift, and magnetic field variations, requiring initial calibration with known actual angles for linearization, which is not feasible in all scenarios.

Innovation Solution

The system employs orthogonal magnetic field sensing elements to determine initial rotation angles and speeds, differentiates these signals to extract harmonic frequencies, integrates them to identify angle errors, and applies these errors as linearization coefficients for continuous self-linearization without requiring knowledge of actual rotation angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If initial calibration with known actual angles is performed for linearization, then measurement accuracy is improved, but device complexity and operational constraints increase due to calibration requirements

Engineering Contradiction:
Improverotation angle measurement accuracyVSAvoidcalibration process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor device performs self-linearization by processing its own output signals. The device extracts speed signals from its angle measurements, identifies harmonic components, integrates them to obtain error signals, and applies these errors to linearize future measurements - all without external calibration equipment or known actual angles.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses feedback by continuously processing measured angle signals to generate correction signals. The extracted speed signals and identified harmonics are integrated to produce error signals that feed back into the measurement system, continuously improving accuracy through adaptive linearization.

Inventive Principle:
Principle #23Feedback

2Reliability

If continuous self-linearization is applied to address changes in nonlinearities, then measurement accuracy is maintained over time, but processing time and computational complexity increase

Engineering Contradiction:
Improvemeasurement accuracy stabilityVSAvoidlinearization processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The sensor device continuously performs linearization by constantly extracting speed signals from angle measurements, identifying harmonic components, and applying correction signals. This continuous operation ensures that nonlinearities are addressed in real-time as they occur, maintaining measurement accuracy without interruption.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system performs preliminary extraction of speed signals and identification of harmonic components before applying linearization corrections. By preparing correction data in advance from the measured signals themselves, the device can efficiently apply linearization without requiring time-consuming external calibration procedures.

Inventive Principle:
Principle #10Preliminary action

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

Enables continuous self-linearization of rotation angle measurements, compensating for errors over time, and maintaining accuracy without needing initial calibration with actual angles, thus addressing nonlinearities and dynamic changes.

Implementation Method 1

magnetic field sensing elements for sensing a magnetic field generated by a rotating target

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

The speeds of rotation are determined by numerically differentiating the initial values of angles of rotation with respect to time

Methodology Applied
Scientific EffectNumerical differentiation:

Implementation Method 3

identifying the signals of different frequencies comprises computing a Fourier transform of the extracted speeds

Methodology Applied
Scientific EffectFourier transform:

Implementation Method 4

determining the angle error values comprises integrating the identified signals of different frequencies to obtain the angle error values as a function of time

Methodology Applied
Scientific EffectIntegration:

Data Source

PatentEP4650724A1Systems, methods, and techniques for linearizing sensor device measurements
Publication Date: 2025.11.19 ALLEGRO MICROSYSTEMS LLC
  • EP4650724A1 patent drawingFigure 1A~1B
  • EP4650724A1 patent drawingFigure 2A~2B
  • EP4650724A1 patent drawingFigure 3A

AI summary

Disclosed are systems, methods, and techniques for linearizing sensor device rotation angle measurements. In particular, described are systems, methods, and techniques for linearizing sensor device rotation angle measurements without knowledge of actual rotation angles of a target. That is, using systems, methods, and techniques disclosed herein, a sensor device may self-linearize rotation angle measurements of a target. In some embodiments, a linearization process may be applied continuously or periodically over time so as to address changes in the nonlinearities of a rotation angle measurement system.