Rotational Angle Sensor Diagnostic Logic for Noise Immunity

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Solution Overview

Problem

Existing rotational angle sensor diagnostic techniques face challenges in accurately determining sensor normality due to noise interference, leading to potential false failures and unnecessary system transitions to fail-safe operations.

Innovation Solution

A diagnostic apparatus and control apparatus that analyze the sum of squares of sine and cosine wave signals from a rotational angle sensor, canceling failure determinations when the signal values are within a predetermined range and the rotational angle is not 0°, 90°, 180°, or 270°, thereby improving normality determination accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the normal range is set taking into account variation in generating circuits to ensure reliable failure detection, then the diagnostic reliability is improved, but the measurement precision deteriorates due to inability to distinguish noise from actual failures

Engineering Contradiction:

Improvefailure detection reliabilityVSAvoidnormality determination accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The diagnostic determination is segmented into multiple independent criteria: (1) sum of squares check, (2) rotational angle check, and (3) angle type check. All three criteria must be satisfied simultaneously to cancel a failure determination, preventing false positives from noise while maintaining reliable failure detection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rotational angle information serves as an intermediary parameter that mediates between the sum of squares check and the final failure determination. By introducing this intermediate verification step, the system can distinguish between actual sensor failures and temporary noise interference

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the system immediately cancels failure determination when sum of squares is within normal range to improve responsiveness, then the system responsiveness is improved, but the diagnostic reliability deteriorates due to potential false cancellations

Engineering Contradiction:

Improvediagnostic response speedVSAvoidfailure determination accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary verification checks (rotational angle validation and angle type exclusion) before canceling the failure determination. This preliminary action ensures that only genuine false positives are canceled, maintaining high reliability while achieving fast response to legitimate sensor recoveries

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10712173B2Diagnostic apparatus and diagnostic method for rotational angle sensor, and control apparatus for actuator

Publication Date: 2020.07.14 ASTEMO LTD

AI summary

A diagnostic apparatus for a rotational angle sensor that outputs two correlated signals, corresponding to a rotational angle, determines whether or not a failure has occurred in the rotational angle sensor based on whether or not a numerical value obtained from the two correlated signals is within a predetermined range. Then, in a case in which the diagnostic apparatus for the rotational angle sensor determines that the failure has occurred in the rotational angle sensor, the diagnostic apparatus cancels the determination that the failure has occurred in the rotational angle sensor, when the numerical value is within the predetermined range and the rotational angle obtained from the two correlated signals is an angle that cannot be recognized to be 0°, 90°, 180°, or 270°.