Application of a Multimodal Deep Learning Model Based on Recursive Fusion Feature Map With Transformer–TCN for Complex Fault Diagnosis of Flying Wing UAV Actuators

The present paper proposes a multimodal deep learning model based on Recursive Fusion Feature Map (RFFM) and Transformer-TCN, to solve the problem of fault diagnosis of flying wing UAV actuators under complex working conditions. The challenges of data scarcity, high-dimensional nonlinear dynamic characteristics, and the difficulty of effectively fusing multimodal features are particularly relevant in this context. The recursive fusion feature map is used to extract high-order features from multi-modal time-series signals (position, velocity, acceleration, torque, current and voltage), and the Transformer is used to capture the long-term dependencies of the signals, while the TCN is employed to model short-term dynamic characteristics. This enables accurate classification and health assessment of the flying wing UAV actuator under normal, single fault (wear/jamming, dynamic lag, signal failure) and compound fault modes. In the simulation experiment, the six-modal time-series signal generated for the seven states was analysed. The experimental findings demonstrated that the proposed model attained a classification accuracy of 98.6% on the bal-anced dataset and 94.7% on the unbalanced dataset, with an F1 score exceeding 0.92 for each category. Concur-rently, the model’s resilience to complex fault modes was substantiated through a comparison of residual signals and an examination of time-frequency diagrams. A comparison of the model with traditional methods such as SVM, random forest and LSTM reveals significant advantages in key indicators such as average AUC value, diagnostic accuracy and classification stability (average AUC value exceeds 0.97). The research results demonstrate the effec-tiveness and applicability of this method in the complex fault diagnosis of flying wing UAV actuators and have important engineering application value and potential for promotion.