In the fast-paced world of railway vehicle design, efficiency and accuracy are paramount. A groundbreaking development by Junya Yoshida of Hitachi’s Center for Technology Innovation-Production Engineering and MONOZUKURI is set to revolutionize how design documents are managed and shared. Yoshida and his team have developed an automatic tagging system for design documents that leverages Bill of Materials (BOM) information, promising to streamline information retrieval and enhance knowledge sharing among experts.
The system integrates advanced natural language processing techniques to extract specialized railway component names from design documents. “We utilized a BERT + CRF-based Named Entity Recognition (NER) model to accurately identify these components,” Yoshida explains. This precision is crucial for maintaining the integrity and relevance of the design documents.
But the innovation doesn’t stop at mere identification. The system goes a step further by using an LDA (Latent Dirichlet Allocation)-based model to infer potential tags. This model learns the latent structural relationships among component names from BOM data, converting hierarchical assembly structures into a Bag of Words (BoW) vector. This allows the system to capture co-occurrence patterns and produce meaningful topic distributions, significantly enhancing the tagging process.
The impact of this technology is substantial. By making relevant design information more accessible, it supports a more efficient Digital Transformation (DX)-driven production environment. “This technology can enhance the accessibility of relevant design information, contributing to a more efficient DX-driven production environment,” Yoshida notes.
The system’s effectiveness was verified using 69 railway design documents manually tagged with reference component names. The evaluation, based on precision, recall, and F1 score, confirmed that the proposed LDA-based tag estimation model significantly outperforms the traditional TF-IDF approach. With an F1 score approximately three times higher than that obtained by TF-IDF, the results demonstrate the effectiveness of leveraging BOM information to model latent structural relationships among component names.
This research, published in the Journal of the Japan Society of Mechanical Engineers (Nihon Kikai Gakkai ronbunshu), opens up new possibilities for the energy sector and beyond. As industries increasingly rely on digital transformation to drive efficiency and innovation, systems like Yoshida’s automatic tagging tool will play a pivotal role in shaping the future of design and production processes.
The implications are far-reaching. By facilitating efficient information retrieval and supporting knowledge sharing, this technology can accelerate project timelines, reduce errors, and foster collaboration among experts. As the energy sector continues to evolve, such advancements will be crucial in meeting the demands of a rapidly changing industry.
In essence, Yoshida’s work is not just about improving tagging systems; it’s about transforming how we approach design and production in the digital age. As industries strive for greater efficiency and accuracy, this research offers a glimpse into the future of smart, data-driven manufacturing.

