An explainable artificial intelligence approach for unsupervised fault detection and diagnosis in rotating machinery

• Published in: Mechanical systems and signal processing 2022-01, Vol.163, p.108105, Article 108105
• Main Authors: Brito, Lucas C., Susto, Gian Antonio, Brito, Jorge N., Duarte, Marcus A.V.
• Format: Article
• Language: English
• Subjects: Algorithms; Anomalies; Anomaly detection; Artificial intelligence; Condition monitoring; Deep learning; Explainable artificial intelligence; Fault detection; Fault diagnosis; Feature extraction; Machine learning; Machinery; Mathematical models; Modularity; Modules; Root cause analysis; Rotating machinery
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2021.108105

•An unsupervised approach for fault detection in rotating machinery.•An unsupervised approach for fault classification based on feature importance ranking.•Possibility of performing root cause analysis and to be applied in different faults.•A new contribution to Explainable Artificial Intelligence in rotating machinery.•Industrial application with the possibility to change models according to the dataset. The monitoring of rotating machinery is an essential task in today’s production processes. Currently, several machine learning and deep learning-based modules have achieved excellent results in fault detection and diagnosis. Nevertheless, to further increase user adoption and diffusion of such technologies, users and human experts must be provided with explanations and insights by the modules. Another issue is related, in most cases, with the unavailability of labeled historical data that makes the use of supervised models unfeasible. Therefore, a new approach for fault detection and diagnosis in rotating machinery is here proposed. The methodology consists of three parts: feature extraction, fault detection and fault diagnosis. In the first part, the vibration features in the time and frequency domains are extracted. Secondly, in the fault detection, the presence of fault is verified in an unsupervised manner based on anomaly detection algorithms. The modularity of the methodology allows different algorithms to be implemented. Finally, in fault diagnosis, Shapley Additive Explanations (SHAP), a technique to interpret black-box models, is used. Through the feature importance ranking obtained by the model explainability, the fault diagnosis is performed. Two tools for diagnosis are proposed, namely: unsupervised classification and root cause analysis. The effectiveness of the proposed approach is shown on three datasets containing different mechanical faults in rotating machinery. The study also presents a comparison between models used in machine learning explainability: SHAP and Local Depth-based Feature Importance for the Isolation Forest (Local-DIFFI). Lastly, an analysis of several state-of-art anomaly detection algorithms in rotating machinery is included.