Engine Health State Index (EHSI)

##plugins.themes.bootstrap3.article.main##

##plugins.themes.bootstrap3.article.sidebar##

Published Jul 3, 2026
Rohit Deo Aman Yadav Shruti Bharti Nilesh Powar

Abstract

Assessing the health of diesel engines is challenging due to multiple coexisting failure modes, overlapping fault signatures, and highly imbalanced operational data. This paper proposes an Engine Health State Index (EHSI), a probabilistic health metric that aggregates risk estimates from multiple failure-code–specific models.

The framework employs a collection of binary classifiers, each trained to estimate the likelihood of a specific failure code from historical telemetry and diagnostic data. At each time step, the resulting failure risk vector provides a distributed representation of latent fault exposure rather than a single dominant failure mode. EHSI maps this risk distribution to a scalar health index using normalized uncertainty measures, enabling continuous tracking of health degradation without relying on explicit fault triggers.

Experiments on real-world diesel engine datasets show that EHSI produces smooth and interpretable health trajectories that correlate with impending failures while remaining sensitive to early-stage degradation. The proposed approach is model-agnostic, extensible to additional failure modes, and suitable for large-scale fleet monitoring applications.

How to Cite

Deo, R., Yadav, A., Bharti, S., & Powar, N. (2026). Engine Health State Index (EHSI). PHM Society European Conference, 9(1), 1–10. https://doi.org/10.36001/phme.2026.v9i1.4995
Abstract 0 | PDF Downloads 0

##plugins.themes.bootstrap3.article.details##

Keywords

Remaining Useful Life, Prognostics, Predictive Maintenance, Engine Health Monitoring, Downtime reduction

References
Cao, H., Yu, J., & Duan, F. (2025). Condition-based maintenance in complex degradation systems: A review of modeling evolution, multi-component systems, and maintenance strategies. Machines, 13(8), 714. https://doi.org/10.3390/machines13080714

Zhang, Y., Fang, L., Qi, Z., & Deng, H. (2023). A review of remaining useful life prediction approaches for mechanical equipment. IEEE Sensors Journal, 23(24), 29991–30006. https://doi.org/10.1109/JSEN.2023.3326487

Qiu, S., Cui, X., Ping, Z., Shan, N., Li, Z., Bao, X., & Xu, X. (2023). Deep learning techniques in intelligent fault diagnosis and prognosis for industrial systems: A review. Sensors, 23(3), 1305. https://doi.org/10.3390/s23031305

Yuan, C., & Liu, S. (2024). Multi-attribute maintenance decision making for aircraft engines based on entropy weight TOPSIS approach. In Proceedings of the 2024 Global Reliability and Prognostics and Health Management Conference (PHM-Beijing) (pp. 1–6). IEEE. https://doi.org/10.1109/PHMBeijing63284.2024.10874564

Nguyen, K. T. P., & Medjaher, K. (2021). An automated health indicator construction methodology for prognostics based on multi-criteria optimization. ISA Transactions, 113, 81–96. https://doi.org/10.1016/j.isatra.2020.03.017

Bajarunas, K., Baptista, M. L., Goebel, K., & Arias Chao, M. (2024). Health index estimation through integration of general knowledge with unsupervised learning. Reliability Engineering & System Safety, 251, 110352. https://doi.org/10.1016/j.ress.2024.110352

Qin, Y., Yang, J., Zhou, J., Pu, H., & Mao, Y. (2023). A new supervised multi-head self-attention autoencoder for health indicator construction and similarity-based machinery RUL prediction. Advanced Engineering Informatics, 56, 101973. https://doi.org/10.1016/j.aei.2023.101973

Yong, B. X., & Brintrup, A. (2022). Coalitional Bayesian autoencoders: Towards explainable unsupervised deep learning with applications to condition monitoring under covariate shift. Applied Soft Computing, 123, 108912. https://doi.org/10.1016/j.asoc.2022.108912

De Giorgi, M. G., Menga, N., & Ficarella, A. (2023). Exploring prognostic and diagnostic techniques for jet engine health monitoring: A review of degradation mechanisms and advanced prediction strategies. Energies, 16(6), 2711. https://doi.org/10.3390/en16062711

Zhang, P., Cao, L., Dong, F., Gao, Z., Zou, Y., Wang, K., Zhang, Y., & Sun, P. (2022). A study of hybrid predictions based on the synthesized health indicator for marine systems and their equipment failure. Applied Sciences, 12(7), 3329. https://doi.org/10.3390/app12073329

Shcherbakov, M., & Sai, C. (2022). A hybrid deep learning framework for intelligent predictive maintenance of cyber-physical systems. ACM Transactions on Cyber-Physical Systems, 6(2), Article 17. https://doi.org/10.1145/3486252

Medjaher, K., Tobon-Mejia, D. A., & Zerhouni, N. (2012). Remaining useful life estimation of critical components with application to bearings. IEEE Transactions on Reliability, 61(2), 292–302. https://doi.org/10.1109/TR.2012.2194175

Mosallam, A., Medjaher, K., & Zerhouni, N. (2016). Data-driven prognostic method based on Bayesian approaches for direct remaining useful life prediction. Journal of Intelligent Manufacturing, 27, 1037–1048. https://doi.org/10.1007/s10845-014-0933-4

Wang, T., Yu, J., Siegel, D., & Lee, J. (2008). A similarity-based prognostics approach for remaining useful life estimation of engineered systems. In Proceedings of the International Conference on Prognostics and Health Management (pp. 1–6). IEEE. https://doi.org/10.1109/PHM.2008.4711421

Liu, B., Gao, Z., Lu, B., Dong, H., & An, Z. (2022). Deep learning-based remaining useful life estimation of bearings with time-frequency information. Sensors, 22(19), 7402. https://doi.org/10.3390/s22197402

Chen, L., Xu, G., Zhang, S., Yan, W., & Wu, Q. (2020). Health indicator construction of machinery based on end-to-end trainable convolution recurrent neural networks. Journal of Manufacturing Systems, 54, 1–11. https://doi.org/10.1016/j.jmsy.2019.11.008

Guo, L., Lei, Y., Li, N., Yan, T., & Li, N. (2018). Machinery health indicator construction based on convolutional neural networks considering trend burr. Neurocomputing, 292, 142–150. https://doi.org/10.1016/j.neucom.2018.02.083

Xu, F., Huang, Z., Yang, F., Wang, D., & Tsui, K. L. (2020). Constructing a health indicator for roller bearings by using a stacked auto-encoder with an exponential function to eliminate concussion. Applied Soft Computing, 89, 106119. https://doi.org/10.1016/j.asoc.2020.106119

Kaji, M., Parvizian, J., & van de Venn, H. W. (2020). Constructing a reliable health indicator for bearings using convolutional autoencoder and continuous wavelet transform. Applied Sciences, 10(24), 8948. https://doi.org/10.3390/app10248948.
Section
Technical Papers