PHM–GPT: A Large Language Model for Prognostics and Health Management

In the digital transformation era of the fourth industrial revolution, prognostics and health management (PHM) is playing increasingly important roles in various engineering fields. As the complexity of industrial systems continues to increase, model-based or data-driven PHM technologies face growing challenges related to interpretability, generalization, and applicability, which limit the widespread deployment of PHM technologies. To address these challenges, this PHM–GPT, a large language model (LLM) specifically designed for PHM, is proposed in this paper. By leveraging LLMs, the PHM–GPT unifies anomaly detection, fault diagnosis, and maintenance decision-making tasks, enabling robust generalization across diverse datasets. In detail, a signal–to–text (S2T) pipeline is presented to develop the InsPHM-456k dataset, focusing on representative components such as bearings and gears. Furthermore, a novel framework for adapting general-purpose LLMs into PHM-specific LLMs is proposed through knowledge injection-based pretraining, PHM-specific instruction tuning, and downstream application fine-tuning during PHM. Additionally, an efficient architecture is introduced to incorporate low-rank adaptation adapters into the group attention module and the feedforward neural network. To validate the effectiveness of the PHM–GPT, extensive simulation studies are conducted, demonstrating its strong generalization across diverse datasets and its broad applicability to machinery components such as bearings and gears. Beyond automatically providing anomalies, diagnoses, and maintenance results, the PHM–GPT exhibits emergent abilities that have never been observed before, such as attribution reasoning, threshold setting, and knowledge discovery, which contribute to enhanced qualitative interpretability and deeper insight into system behaviors. Finally, this paper provides new insights into the PHM field and explores the future of LLMs in terms of advancing PHM technology deployment, accelerating the digital transformation process during the fourth industrial revolution.