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Anomaly Detection of DC Nut Runner Processes in Engine Assembly

James Simon Flynn Orcid Logo, Cinzia Giannetti Orcid Logo, Hessel Van Dijk

AI, Volume: 4, Issue: 1, Pages: 234 - 254

Swansea University Author: Cinzia Giannetti Orcid Logo

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DOI (Published version): 10.3390/ai4010010

Abstract

In many manufacturing systems, anomaly detection is critical to identifying process errors and ensuring product quality. This paper proposes three semi-supervised solutions to detect anomalies in Direct Current (DC) Nut Runner engine assembly processes. The nut runner process is a challenging anomal...

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Published in: AI
ISSN: 2673-2688
Published: MDPI AG 2023
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa62914
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Abstract: In many manufacturing systems, anomaly detection is critical to identifying process errors and ensuring product quality. This paper proposes three semi-supervised solutions to detect anomalies in Direct Current (DC) Nut Runner engine assembly processes. The nut runner process is a challenging anomaly detection problem due to the manual nature of the process inducing high variability and ambiguity of the anomalous class. These characteristics lead to a scenario where anomalies are not outliers, and the normal operating conditions are difficult to define. To address these challenges, a Gaussian Mixture Model (GMM) was trained using a semi-supervised approach. Three dimensionality reduction methods were compared in pre-processing: PCA, t-SNE, and UMAP. These approaches are demonstrated to outperform the current approaches used by a major automotive company on two real-world datasets. Furthermore, a novel approach to labelling real-world data is proposed, including the concept of an ‘Anomaly No Concern’ class, in addition to the traditional labels of ‘Anomaly’ and ‘Normal’. Introducing this new term helped address knowledge gaps between data scientists and domain experts, as well as providing new insights during model development and testing. This represents a major advancement in identifying anomalies in manual production processes that use handheld tools.
Keywords: GMM, UMAP, PCA, t-SNE, quality assurance, anomaly detection, nut runner
College: Faculty of Science and Engineering
Funders: Funded by M2A COATED2 CDT
Issue: 1
Start Page: 234
End Page: 254