Self-Supervised Reinforcement Learning for Ship Detection in SAR Range-Compressed Domain
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摘要: 合成孔径雷达(SAR)具备全天时全天候的海上监视能力。在距离压缩域(RCD)直接进行舰船目标检测,可规避计算密集的成像步骤(如距离徙动校正与方位压缩),从而显著提升处理效率,适用于近实时或实时处理场景。然而,现有检测方法存在固有局限:一方面,传统恒虚警率(CFAR)检测器依赖于固定统计模型,在复杂海杂波环境下表现不佳;另一方面,深度学习方法普遍存在依赖已标注数据、解释性弱以及相位信息利用不充分等问题。为此,该文提出了一种基于自监督强化学习的SAR距离压缩域舰船目标检测框架,有效融合雷达电磁散射模型与深度强化学习优势,在提升检测性能的同时增强模型的解释性与泛化能力。该框架具有以下特点:(1)引入统计模型约束的奖励信号生成机制,实现了无需人工标注的自监督学习;(2)设计双模态特征融合模块,能够联合表征幅度与相位信息,有效保留舰船的多普勒特征;(3)提出轻量化的智能体模块,集成轻量化Q网络、自适应特征增强模块和鉴别器网络,在降低计算复杂度的同时满足实时处理需求,并借助对抗性训练增强模型的鲁棒性。实验结果表明,所提方法在近20k×20k像素的大场景SAR距离压缩域数据上的平均推理时间仅为31.75 s,计算量仅为二维卷积神经网络的23.81%。在复数RCD数据集上,该方法的F1分数与召回率分别达到50.72%和54.28%,相较于主流自监督检测方法提升了8.76%和10.45%。该研究首次将强化学习引入SAR距离压缩域舰船检测,通过信号模型与数据驱动学习的结合,为实现稳健的海上监视提供了新思路。
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关键词:
- 合成孔径雷达(SAR) /
- 舰船目标检测 /
- 深度强化学习 /
- 距离压缩域 /
- 自监督检测方法
Abstract: Synthetic aperture radar (SAR) offers all-weather, all-day maritime surveillance capabilities. Direct ship detection in the range compressed domain (RCD) eliminates computationally intensive imaging steps—such as range cell migration correction and azimuth compression—thereby considerably improving processing efficiency for near-real-time or real-time applications. However, current detection methods face inherent limitations; traditional constant false alarm rate detectors rely on fixed statistical models and often underperform in complex sea clutter environments. In addition, deep learning approaches heavily rely on annotated data and do not fully leverage phase information; moreover, they exhibit weak interpretability. To address these issues, this paper proposes a self-supervised reinforcement learning framework for ship target detection in the SAR RCD. This framework effectively integrates the physical principles of radar signals with deep reinforcement learning, achieving enhanced detection performance while improving model interpretability and generalization. The framework has the following characteristics: (1) it introduces a reward signal-generation mechanism constrained by statistical scattering models, achieving self-supervised learning without the need for manual annotation; (2) it designs a dual-modal feature-fusion module that can jointly represent amplitude and phase information, effectively retaining the Doppler characteristics of ships; and (3) it adopts a lightweight agent module that integrates a lightweight Q-network, an adaptive feature enhancement module, and a discriminator network; this module reduces computational complexity, meets real-time processing requirements, and enhances the robustness of the model through adversarial training. Experimental results demonstrate that the proposed method achieves an average inference time of only 31.75 s on a large-scale SAR RCD dataset of 20k × 20k pixels, with a computational load of only 23.81% compared with a two-dimensional convolutional neural network. On a complex-valued RCD dataset, the method attains F1 and recall scores of 50.72% and 54.28%, respectively, outperforming mainstream self-supervised methods by 8.76% and 10.45%, respectively. This study pioneers the application of reinforcement learning to ship detection using SAR RCD, offering a novel approach to robust maritime surveillance by integrating signal modeling and data-driven learning. -
表 1 实验数据集相关信息
Table 1. Information on the experimental dataset
参数名称 指标 总样本数量 8,742 每个样本的距离单元数 1024 舰船数量 14,926 卫星载荷平台 Sentinel-1 极化方式 VV, VH 入射角 20°–45° 表 2 训练超参数配置
Table 2. Training hyperparameter configuration
参数类别 设置值 优化器 Adam 初始学习率 1e-4 学习率调度 余弦退火 批大小(batch size) 32 训练轮次(epoch) 500 CFAR阈值乘数 2.5 超参数调整策略 网格策略 表 3 不同阈值乘数取值下的本文方法检测性能
Table 3. Detection performance under different threshold multiplier values
取值 精确率(%) 召回率(%) F1分数(%) 相对F1变化(%) 1.5 41.20 58.50 48.34 –2.38 2.0 44.82 56.21 49.87 –0.85 2.5 47.60 54.28 50.72 0.00 3.0 48.50 52.13 50.25 –0.47 3.5 50.34 49.78 50.06 –0.66 表 4 消融实验结果
Table 4. The results of the ablation experiment
网络各模块组件 参数量(M) 性能指标(%) 深度强化学习 统计模型约束奖励 双模态融合 鉴别器网络 P R F1 AP@50 – – – – 0.0 31.21 28.72 29.91 33.18 √ – – – 3.01 39.89 42.63 41.21 46.23 √ √ – – 3.01 43.73 48.38 45.93 50.82 √ √ √ – 3.35 46.28 51.73 48.85 53.91 √ √ √ √ 4.49 47.60 54.28 50.72 56.13 表 5 自监督方法比较
Table 5. Comparison of Self-supervised Methods
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