Side-scan sonar (SSS) images present unique challenges to computer vision due to their lower resolution, smaller targets, and fewer features. Although the mainstream backbone networks have shown promising results on traditional vision tasks, they utilize traditional convolution to reduce the dimensionality of feature maps, which may cause information loss for small targets and decrease performance in SSS images. To address this problem, based on the yolov8 network, we proposed a new underwater target detection model based on upsampling and downsampling. Firstly, we introduced a new general downsampling module called shallow robust feature downsampling (SRFD) and a receptive field convolution (RFCAConv) in the backbone network. Thereby multiple feature maps extracted by different downsampling techniques can be fused to create a more robust feature map with a complementary set of features. Additionally, an ultra-lightweight and efficient dynamic upsampling module (Dysample) is introduced to improve the accuracy of the feature pyramid network (FPN) in fusing different levels of features. On the underwater shipwreck dataset, our improved model’s mAP50 increased by 4.4% compared to the baseline model.

Fault diagnosis is crucial for ensuring the navigational safety and reliability of unmanned underwater vehicles (UUVs). However, in complex marine environments, UUV fault samples are typically scarce and often contaminated by severe hydraulic noise, which significantly restricts the performance of existing diagnostic methods. To address these challenges, this paper proposes a few-shot fault diagnosis method based on an Adaptive Enhanced Meta-Transformer. First, operational vibration data from UUV actuators are acquired and preprocessed. Second, a feature enhancement module is constructed using an improved Transformer architecture that incorporates a novel Adaptive Head-Weighted Multi-Head Self-Attention mechanism. This mechanism enables the model to precisely localize key fault segments and enhance directional features, even under noisy backgrounds, effectively mitigating attention dispersion. Subsequently, a meta-optimization strategy is employed to iteratively update model parameters, enabling the model to rapidly adapt to new tasks with limited data. Finally, extensive experiments using real-world operational data from UUV actuators demonstrate that the proposed method outperforms state-of-the-art baselines in terms of accuracy and robustness, particularly in cross-component and noisy scenarios.