Machine Defect Detection Using ML-Predicted Condition Indicators

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Solution Overview

Problem

In machine diagnostics, it is challenging to distinguish between changes in condition indicators caused by machine defects and those caused by operating conditions, leading to potential false alarms and missed defect detections, particularly in applications like wind turbines where operating parameters significantly influence behavior.

Innovation Solution

A method and system that utilize machine learning algorithms, specifically neural networks, to establish a relationship between operating condition data and condition indicator values, allowing for the prediction of indicator values under normal conditions and comparison with current values to accurately detect defects by accounting for fluctuations due to operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If alarm levels are set high to avoid false alarms caused by operating condition fluctuations, then false alarm rate is reduced, but defect detection capability deteriorates

Engineering Contradiction:
Improvefalse alarm rateVSAvoiddefect detection capability
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the condition indicator analysis into two distinct components: a baseline component representing normal operating condition fluctuations, and a defect component representing actual machine defects. By training a machine learning model to learn the baseline behavior from historical data during normal operation, the system can subtract this expected behavior from current readings, isolating only the defect-related deviations. This segmentation allows lower alarm thresholds without increasing false alarms, as the baseline variability is already accounted for.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary action by collecting and analyzing historical operating data during normal machine operation to establish a baseline behavior model before actual defect detection begins. The machine learning algorithm is trained in advance on data from multiple operating conditions to learn how condition indicators naturally fluctuate with changes in load, speed, and environmental factors. This preliminary learning phase enables the system to distinguish between normal variability and defect-induced changes, allowing for more sensitive defect detection without false alarms.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If alarm levels are set low to improve defect detection sensitivity, then defect detection capability is improved, but false alarm rate increases

Engineering Contradiction:
Improvedefect detection capabilityVSAvoidfalse alarm rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system implements feedback by continuously comparing current condition indicator readings against the machine learning model's predictions of normal behavior. The difference between actual and predicted values (residuals) is analyzed to detect defects. When a defect occurs, it causes deviations from the learned baseline pattern, generating feedback signals that trigger alerts. This feedback mechanism enables low alarm thresholds because the system only triggers when there is a genuine deviation from the baseline, not during normal operating condition changes.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The machine learning model acts as an intermediary between the raw condition indicator data and the defect detection decision. Instead of directly comparing current readings to fixed alarm thresholds, the system uses the ML model to predict what the reading should be under current operating conditions, then compares the actual reading to this dynamic prediction. This intermediary layer filters out normal operating variability while preserving defect-related signals, enabling sensitive detection without false alarms.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If fixed alarm thresholds are used to simplify defect detection, then system complexity is reduced, but adaptability to different operating conditions deteriorates

Engineering Contradiction:
Improvedetection system complexityVSAvoidadaptability to operating conditions
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent transitions from static fixed thresholds to dynamic adaptive thresholds by using a machine learning model that continuously adapts to changing operating conditions. The model learns the relationship between operating parameters (load, speed, temperature) and condition indicator behavior, enabling the detection threshold to dynamically adjust based on current operating conditions. This dynamic approach maintains high adaptability while the underlying ML model structure provides a systematic framework that manages complexity through automated learning rather than manual configuration.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the parameter used for defect detection from fixed absolute thresholds to relative deviations from predicted baseline behavior. Instead of using a static threshold value, the system calculates the difference between actual condition indicators and ML-predicted values under current operating conditions. This parameter transformation enables the system to adapt to different operating conditions automatically, as the threshold becomes a function of operating parameters rather than a fixed value, improving versatility without proportionally increasing complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11746752B2Method and system for detecting machine defects
Publication Date: 2023.09.05 AB SKF SKF PATENT DEPARTMENT
  • US11746752B2 patent drawing
  • US11746752B2 patent drawing

AI summary

A method for detecting at least one machine defect provides defining from the machine kinematic data at least one condition indicator reflecting its condition, recording operating condition data of the machine and condition monitoring data of the machine during a predetermined period when the machine is operating normally, determining condition indicator values using condition monitoring data, and for determining current condition indicator values from the at least one condition indicator and the current condition monitoring data, a machine learning algorithm, predicting condition indicator values with respect to the current operating condition data, training the machine learning algorithm to establish a relation between the operating condition data and condition indicator values, and comparing the current condition indicator values and the predicted condition indicator values, and for determining if the machine is presumed to operate normally or not according to the result of the comparison.