Auto-calibrating Multi-pole Angle Sensor with Mechanical Modulation Compensation

Solution Overview

Problem

Magnetic field sensors face misalignment issues due to manufacturing tolerances or installation errors, leading to mechanical modulation of signals, which affects the accuracy of angular position, speed, and acceleration measurements.

Innovation Solution

A signal processing technique that identifies local maxima and minima of the magnetic field signal generated by a rotating target, calculates offset and gain adjustment signals based on these summations, and adjusts the signal to compensate for mechanical modulation, thereby correcting signal unevenness caused by misalignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If signal processing is performed without compensation for mechanical modulation, then the device complexity is reduced, but the measurement precision deteriorates due to misalignment-induced signal unevenness

Engineering Contradiction:

Improveangular position measurement accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor system performs self-calibration by automatically detecting its own mechanical modulation characteristics through the modulation detection circuit and processing circuitry, and correcting them using the calculated compensation values, eliminating the need for external calibration equipment or manual adjustment

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses the detected mechanical modulation characteristics to generate feedback signals that are used to adjust and correct the output signals, creating a closed-loop system that continuously compensates for misalignment effects

Inventive Principle:

Principle #23Feedback

2Measurement precision

If manual calibration procedures are implemented to correct misalignment, then the measurement precision improves, but the ease of operation deteriorates due to complex calibration steps

Engineering Contradiction:

Improvesignal accuracyVSAvoidcalibration operation simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The sensor system performs self-calibration by automatically detecting its own mechanical modulation characteristics through the modulation detection circuit and processing circuitry, and correcting them using the calculated compensation values, eliminating the need for external calibration equipment or manual adjustment

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical calibration procedures with an automated electronic signal processing system that detects and corrects mechanical modulation effects through electrical circuits and digital processing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If offset and gain adjustment signals are calculated and applied, then the measurement precision improves, but the device complexity increases due to additional processing circuits

Engineering Contradiction:

Improveangular position measurement accuracyVSAvoidprocessing circuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the mechanical modulation detection function, compensation value calculation, and signal correction functions into an integrated processing circuit that operates within the existing sensor architecture, minimizing additional hardware complexity

Inventive Principle:

Principle #5Merging (Combining)

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 technique effectively compensates for misalignment-induced mechanical modulation, resulting in more even signal peaks and improved accuracy of angular position, speed, and acceleration measurements.

Implementation Method 1

Some sensors include one or magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element, to sense a magnetic field associated with proximity or motion of a target object

Methodology Applied

Scientific EffectHall effect: Hall Effect

Implementation Method 2

Some sensors include one or magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element, to sense a magnetic field associated with proximity or motion of a target object

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Data Source

PatentUS20220390257A1Auto-calibration for multi-pole angle sensors with mechanical modulation

Publication Date: 2022.12.08 ALLEGRO MICROSYSTEMS LLC

AI summary

A sensor, comprising: a processing circuitry configured to: receive a first signal that is generated by a first magnetic field sensing element, the first signal being generated in response to a magnetic field that is indicative of rotation of a target; identify N local maxima of the first signal, where N is a positive integer, and N>1; identify N local minima of the first signal; generate a first offset adjustment signal and a first gain adjustment signal based on: (i) a first sum of the local maxima of the first signal and (ii) a second sum of the local minima of the first signal; and adjust the first signal based on the first offset adjustment signal and the first gain adjustment signal.