Defect Detection in Freight Trains Using a Lightweight and Effective Multi-Scale Fusion Framework with Knowledge Distillation

The safe operation of freight train equipment is crucial to the stability of the transportation system. With the advancement of intelligent monitoring technology, vision-based anomaly detection methods have gradually become an essential approach to train equipment condition monitoring. However, due to the complexity of train equipment inspection scenarios, existing methods still face significant challenges in terms of accuracy and generalization capability. Freight trains defect detection models are deployed on edge computing devices, onboard terminals, and fixed monitoring stations. Therefore, to ensure the efficiency and lightweight nature of detection models in industrial applications, we have improved the YOLOv8 model structure and proposed a network architecture better suited for train equipment anomaly detection. We adopted the lightweight MobileNetV4 as the backbone to enhance computational efficiency and adaptability. By comparing it with other state-of-the-art lightweight networks, we verified the superiority of our approach in train equipment defect detection tasks. To enhance the model’s ability to detect objects of different sizes, we introduced the Content-Guided Attention Fusion (CGAFusion) module, which effectively strengthens the perception of both global context and local details by integrating multi-scale features. Furthermore, to improve model performance while meeting the lightweight requirements of industrial applications, we incorporated a staged knowledge distillation strategy on large-scale datasets. This approach significantly reduces model parameters and computational costs while maintaining high detection accuracy. Extensive experiments demonstrate the effectiveness and efficiency of our method, proving its competitiveness compared with other state-of-the-art approaches.