Manufacturing Defect Clustering with CNN Features and PCA

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Solution Overview

Problem

Existing image classification and clustering methods for manufacturing components, particularly in semiconductor production, struggle with misclassifications and require extensive training, making it difficult to adapt to novel and unforeseeable defects, and are time-consuming.

Innovation Solution

A computer-implemented method and system that uses a combination of pre-trained convolutional neural networks (CNN) for feature extraction, principal component analysis (PCA) for dimension reduction, and iterative clustering algorithms like GMM, AC, and DBSCAN, along with a silhouette metric for evaluation, to optimize clustering of input data without requiring labeled data or expert knowledge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional supervised learning approaches or neural networks with similarity search are used for classifying error patterns, then classification accuracy can be improved for known defect types, but the system requires extensive training with precisely labeled data and cannot adapt to novel or unforeseeable defects

Engineering Contradiction:
Improveclassification accuracyVSAvoidadaptability to novel defects
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies preliminary action by using pre-trained convolutional neural networks (CNNs) that have already learned general image features from large datasets. These pre-trained models serve as feature extractors that can be immediately applied to defect detection without requiring extensive task-specific training, thus enabling rapid adaptation to new defect types while maintaining high classification accuracy for known defects.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by transforming the classification problem into a clustering problem in a reduced-dimensional feature space. By applying principal component analysis (PCA) to reduce the dimensionality of CNN-extracted features and using silhouette metrics to evaluate cluster quality, the system adapts its parameters (feature representation, dimensionality) to handle both known and novel defect patterns effectively.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If extensive training with precisely identified or labeled error patterns is performed, then classification reliability is improved, but the process becomes extremely time-consuming and requires expert knowledge

Engineering Contradiction:
Improveclassification reliabilityVSAvoidtraining time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies self-service by implementing an unsupervised clustering approach that automatically discovers defect patterns without requiring human experts to manually label training data. The system uses silhouette metrics to automatically evaluate and select optimal cluster configurations, enabling the model to improve its own classification reliability through self-organized learning rather than time-consuming manual annotation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent uses pre-trained CNN models as feature extractors that have already undergone extensive training on general image data. This preliminary training provides a strong foundation that can be immediately applied to defect detection tasks, eliminating the need for time-consuming task-specific training while maintaining high reliability through the transfer of learned features.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If iterative clustering methods are applied to improve clustering quality, then clustering accuracy is enhanced, but the computing effort and complexity increase

Engineering Contradiction:
Improveclustering accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies the extraction principle by separating the feature extraction task (performed by pre-trained CNNs) from the clustering task. By extracting meaningful features in advance using established CNN architectures and then applying relatively simple clustering algorithms (k-means, GMM, DBSCAN) to these extracted features, the system achieves high clustering accuracy without the need for complex iterative optimization, thus reducing computational complexity while maintaining precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs dimensionality change by applying principal component analysis (PCA) to transform high-dimensional CNN features into a lower-dimensional space that preserves the most important variance. This dimensionality reduction simplifies the subsequent clustering task, allowing standard clustering algorithms to achieve high accuracy with reduced computational complexity compared to operating in the original high-dimensional space.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20250284775A1Computer-implemented method and system for optimizing a clustering of a plurality of input data
Publication Date: 2025.09.11 ROBERT BOSCH GMBH
  • US20250284775A1 patent drawing
  • US20250284775A1 patent drawing

AI summary

A computer-implemented method and system for optimizing a clustering of a plurality of input data. The method includes: providing a plurality of input data of a manufacturing component to be inspected; extracting at least one feature from the plurality of input data by applying an extraction algorithm; clustering the plurality of input data on the basis of the at least one feature by applying a clustering algorithm; evaluating clusters of the clustered plurality of input data by applying a cluster evaluation algorithm; sorting out, from the plurality of input data, input data that are assigned to at least one cluster with a high rating and/or that exceed a predetermined limit number of input data within the at least one cluster with the high rating; and repeating iteratively certain steps until the plurality of input data is completely clustered and/or evaluated, and/or until a predetermined termination criterion is reached.