Test-Time Adaptation for Cross-Domain Remaining Useful Life Prediction: When Does It Work and What Should Practitioners Use
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Naval Aviation University, China
A – Conceptualization; B – Methodology; C – Software; D – Validation; E – Formal analysis; F – Investigation; G – Resources; H – Data curation; I – Writing – original draft; J – Writing – review & editing; K – Visualization; L – Supervision; M – Project administration; N – Funding acquisition
Submission date: 2026-05-10
Final revision date: 2026-07-06
Acceptance date: 2026-07-17
Online publication date: 2026-07-29
Publication date: 2026-08-13
Corresponding author
Jianyin Zhao
Naval Aviation University, 188 Erma Road, Dongshan Subdistrict, Zhifu Distric, 264001, Yantai City, Shandong Province, China
Eksploatacja i Niezawodność – Maintenance and Reliability 2027;29(1):226057
Deep learning models for remaining useful life (RUL) prediction degrade under varying operating conditions due to distribution shifts. Test-time adaptation (TTA) addresses this issue by updating a pretrained model using unlabeled target data without source data access; however, it has not been systematically studied for RUL prediction. Four TTA strategies are reformulated and evaluated across six cross-domain scenarios on C-MAPSS. TTA improves performance only when the source has more diverse operating conditions than the target. Restricting adaptation to batch-normalization (BN) affine parameters makes all gradient-based methods produce functionally equivalent outputs (BN affine bottleneck). Gradient-free adaptive BN gives the best risk–benefit trade-off, matching or outperforming them in five of six scenarios. A four-step deployment workflow for cross-domain predictive maintenance is proposed. The direction dependence of TTA effectiveness and the BN affine bottleneck are further confirmed on an LSTM backbone and the N-CMAPSS dataset.