Redundant Acquisition Channel Arbitration for False Fault Localization

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Solution Overview

Problem

Current duplex acquisition systems face high rates of false fault localization, leading to unsafe regulation in aircraft turbine engines due to the inaccuracy of arbitration models compared to sensor precision, which can result in amplification of faults rather than mitigation.

Innovation Solution

Implementing a method where fault detection and localization are distinguished phases, with a detection threshold based on sensor precision and a separate location threshold, allowing for a waiting period to reduce the risk of incorrect localization by ensuring the system operates with the non-defective channel until the faulty channel's deviation exceeds a defined failure threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If fault localization is performed simultaneously with detection using a model-based arbitration method, then fault localization capability is provided, but false localization rate increases due to model inaccuracy compared to sensor precision

Engineering Contradiction:
Improvefault localization capabilityVSAvoidlocalization accuracy
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent segments the fault management process into two distinct phases: detection phase and localization phase. The detection phase uses sensor precision-based thresholds to identify potential faults, while the localization phase uses model-based arbitration only after detection. This segmentation prevents premature localization decisions that would be inaccurate due to model limitations, thereby reducing false localization rates while maintaining localization capability.

Inventive Principle:
Principle #1Segmentation

2Loss of time

If the arbitration model is used for immediate fault localization, then system response time is reduced, but the accuracy of localization deteriorates due to model precision being worse than sensor precision

Engineering Contradiction:
Improvefault localization timeVSAvoidlocalization precision
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by performing detection first using high-precision sensor data before proceeding to localization. The detection phase prepares the system by identifying potential faults with high accuracy, allowing the subsequent localization phase to focus computational resources on confirmed anomalies. This preliminary detection step ensures that localization is only attempted when necessary and with higher confidence, reducing both false localizations and unnecessary delays.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If a single threshold is used for both detection and localization, then the system complexity is reduced, but the ability to distinguish between detection and localization requirements deteriorates

Engineering Contradiction:
Improvethreshold management complexityVSAvoidfault management reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by implementing different threshold characteristics for different phases of fault management. The detection threshold is optimized for sensitivity to actual faults using sensor precision, while the localization threshold (or arbitration criteria) is optimized for distinguishing between multiple potential fault sources using model predictions. This differentiated approach ensures each phase has the appropriate sensitivity and specificity for its purpose, improving overall reliability despite increased complexity in threshold management.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3938910B1Fault localisation within a redundant acquisition system
Publication Date: 2023.06.07 SAFRAN AIRCRAFT ENGINES SAS
  • EP3938910B1 patent drawingFigure 1~2
  • EP3938910B1 patent drawingFigure 3

AI summary

The present invention relates to a method for detecting and locating a faulty measurement-acquisition channel in an acquisition system (10) comprising two redundant acquisition channels (A, B) for measuring a physical quantity in an environment, the method using a computing unit (20) comprising a memory (24) storing a model (Mod) of the measured physical quantity, the method implementing the following steps: - (E1) detecting an error when a discrepancy (∆) between the measured values of the two channels (A, B) reaches a detection threshold (Th_D); - (E2) waiting to let the acquisition system undergo changes for a certain length of time (T); - (E3) locating the defective channel among the two channels (A, B), when the discrepancy (∆) in the measured values between the channels (A, B) reaches a location threshold (Th_L), said locating being performed on the basis of the comparison of the measured value of each of the channels (A, B) with a modelled value of the physical quantity, the location threshold (Th_L) being different from the detection threshold (Th_D).