Angle Sensor Safety Mechanism Using Segmented Magnetoresistive and Hall Paths

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Solution Overview

Problem

Existing angle sensors face challenges in ensuring functional safety, particularly in achieving high Automotive Safety Integrity Levels (ASIL) due to potential malfunctions, which can lead to hazards in applications like electronic power steering systems.

Innovation Solution

The implementation of a safety mechanism in angle sensors that utilizes two sets of angle measurement paths with different sensing elements, such as magnetoresistive and Hall-based sensing elements, to determine angular positions and perform safety checks through segment comparison and vector length checks, ensuring that the system can detect failures and maintain accuracy despite temperature and magnetic field variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single angle measurement path is used, then device complexity is reduced, but functional safety and reliability cannot meet high ASIL requirements

Engineering Contradiction:

Improvefunctional safetyVSAvoidmeasurement path structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The angle sensor is divided into multiple independent measurement paths (first and second angle measurement paths), each with its own sensing elements. This segmentation allows redundant measurement capabilities while maintaining manageable complexity in each individual path.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sensing elements are used in different measurement paths (e.g., magnetoresistive in first path, Hall-based in second path). This local quality differentiation provides diversity in measurement principles, enhancing functional safety through cross-validation of measurements from different physical bases.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If multiple sensing elements are used, then measurement accuracy and safety are improved, but susceptibility to temperature and magnetic field variations increases

Engineering Contradiction:

Improveangular position accuracyVSAvoidtemperature and magnetic field variations

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The safety mechanism continuously compares measurements from multiple sensing elements and measurement paths. When deviations beyond threshold values are detected, the system can trigger safety responses. This feedback loop compensates for environmental variations by detecting inconsistencies that indicate malfunction or excessive environmental influence.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary safety checks by comparing measurements from different sensing elements before final angle determination. This preliminary action identifies and filters out measurements affected by temperature or magnetic field variations, ensuring only valid measurements are used for control decisions.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If safety check mechanisms are implemented, then functional safety is enhanced, but processing time and computational load increase

Engineering Contradiction:

Improvesafety assuranceVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The safety mechanism performs partial checks by comparing only critical parameters (angular position consistency between paths, threshold deviations) rather than full signal processing. This selective approach provides adequate safety assurance while minimizing processing time and computational overhead.

Inventive Principle:

Principle #16Partial or excessive 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

This approach enhances the functional safety of angle sensors by providing redundancy and diversity in measurement, allowing for the detection of malfunctions and maintaining accuracy across varying conditions, thereby meeting high ASIL requirements.

Implementation Method 1

a first set of angle sensing elements configured to determine a first x-component value and a first y-component value

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Implementation Method 2

a second set of angle sensing elements configured to determine a second x-component value and a second y-component value from a second set of angle sensing elements

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS11859971B2Safety mechanism for angle sensors using segmentation

Publication Date: 2024.01.02 INFINEON TECHNOLOGIES AG

AI summary

In some implementations, an angle sensor may receive a first x-component value and a first y-component value from a first set sensing elements and a second x-component value and a second y-component value from a second set of angle sensing elements. The angle sensor may perform a safety check including determining a first range of angles associated with a target object based on a relationship between a magnitude of the first x-component value and a magnitude of the first y-component value; determining a second range of angles associated with the target object based on a relationship between a magnitude of the second x-component value and a magnitude of the second y-component value; and determining whether the second range of angles is a subset of the first range of angles. The angle sensor may output an indication of a result of the safety check.