Application of Digital Twin Technology in Synthetic Aperture Radar Ground Moving Target Intelligent Detection System
Abstract
:1. Introduction
- This paper designs an overall framework for SAR moving target intelligent detection based on the integration of DT and artificial intelligence technology. In particular, according to the characteristics of the measured data obtained from a real SAR system, a high-fidelity virtual replica of a current physical system is constructed in digital space. Then, the neural network model is trained on this basis to obtain an intelligent detector that can realize the robust detection of the moving targets in related application scenarios.
- By virtue of the SAR imaging algorithm, the parameters of target motion, position, and SCR (signal–clutter ratio) during echo synthesis are fully traversed to construct the high-fidelity SAR twin datasets, which can fully reflect the characteristics of the moving targets and preset scene in the real system and significantly improve the detection performance and generalization ability of the neural network model in practical application scenarios.
- The effectiveness of the proposed framework is verified on the related measured data obtained by radar sensors. The experimental results indicate that the DT-based framework for SAR ground moving target intelligent detection can effectively realize robust target detection and synchronous state perception in real test scenarios with no need for complex field experiments and is applicable to several SAR systems.
2. Methods
2.1. Physical SAR System
2.2. Virtual Replica of SAR-GMTI
- Target motion parameter traversal
- 2.
- Target position traversal
- 3.
- SCR traversal
2.3. SAR Ground Moving Target Detection Based on Deep Learning
3. Implementation Details
3.1. MiniSAR Measured System
3.2. Construction of MiniSAR Twin Datasets
3.3. SAR Moving Target Intelligent Detection Based on Faster-RCNN
- Feature extraction: To begin with, the feature extraction network generates feature maps used for subsequent RPN layers through convolution and pooling operations. Since SAR images are grayscale images and the targets to be recognized are relatively small, ResNet50 was selected as the backbone network of Faster-RCNN, and an FPN (Feature Pyramid Network) was further introduced to improve the detection performance of the model. In particular, ResNet50 can effectively balance the increasing network layers and the improvement in model performance, which can learn richer semantic information and avoid gradient vanishing and explosion at the same time.
- Multi-scale feature fusion: In the process of feature extraction, the shadow layers contain less semantic information but precise target positions, while the deep layers contain richer semantic information but rough locations. Generally, a CNN (Convolution neural network) adopts the bottom-up feature extraction strategy and only utilizes features of the last layer, which causes a sharp decline in the detection performance of small objects. By comparison, the FPN adopts a bidirectional feature extraction strategy and achieves feature fusion by horizontal connections, which can fully utilize bottom high-resolution features and high-level semantic information for prediction. On the basis of not increasing the computational load, a multi-scale feature pyramid was constructed by simply changing the network connection to realize the robust detection of multi-scale targets.
- Region proposal: An RPN directly processes the feature maps output from the backbone feature extraction network, which generates a series of rectangular region proposals through sliding windows (preset anchors). The convolution results are mapped to feature vectors and then input into fully connected layers for classification and regression. On the one hand, the likelihood probability of the output category is calculated by the SoftMax function, and a binary classification is performed on the anchors (target or background). On the other hand, the coordinates of the bounding boxes that contain targets are predicted and output through the regression layer.
- Classification and regression: The input feature vectors which are generated from the output proposals of the RPN are classified and located by the fully connected layers. Moreover, by virtue of the SoftMax function, the target category in proposals is further classified and the coordinates of the bounding boxes are determined from the regions that contain targets.
4. Experiment Results
4.1. Construction Results of Digital Twin Data
4.2. Validation of DT-Based SAR-GMTI Framework
4.3. Comparative Experiment Results and Analysis
5. Discussion
6. Conclusions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Parameter | Symbol | Value |
---|---|---|
Platform velocity | v | 6 m/s |
Carrier frequency | 9.7 GHz | |
Sample frequency | 0.54 GHz | |
Orbit height | H | 289 m |
Pulse repetition frequency | 1000 Hz | |
Range resolution | 0.33 m | |
Azimuth resolution | 0.25 m |
Parameter | Symbol | Value |
---|---|---|
Orbit height | H | 289 m |
Scene center distance | 649 m | |
Carrier frequency | 9.7 GHz | |
Range modulation frequency | GHz/s | |
Pulse repetition frequency | 1000 Hz | |
Platform velocity | v | 6 m/s |
Orbit radius | r | 581 m |
Sample frequency | 0.54 GHz |
Motion Parameter (, ) | Target Position (Range, Azimuth) | SCR (dB) | Correctly Detected Targets | False Alarms | Missed Targets |
---|---|---|---|---|---|
= 1.5, = 0.006 | (981, 899) | 16 | 183 | 241 | 496 |
= 1.0, = 0.004 | (981, 899) | 16 | 264 | 179 | 415 |
= 0.5, = 0.002 | (981, 899) | 16 | 307 | 154 | 372 |
= 1.0, = 0.004 | = 30 | 16 | 381 | 126 | 298 |
= 1.0, = 0.004 | = 20 | 16 | 436 | 93 | 243 |
= 1.0, = 0.004 | = 10 | 16 | 472 | 71 | 207 |
= 1.0, = 0.004 | = 20 | = 1 | 514 | 48 | 165 |
= 1.0, = 0.004 | = 20 | = 0.5 | 553 | 32 | 126 |
= 0.5, = 0.002 | = 10 | = 0.5 | 618 | 17 | 61 |
SCR (dB) | Correctly Detected Targets | False Alarms | Missed Targets | Precision |
---|---|---|---|---|
12 | 243 | 172 | 436 | 0.586 |
14 | 312 | 141 | 367 | 0.688 |
16 | 357 | 115 | 322 | 0.756 |
18 | 396 | 92 | 283 | 0.811 |
20 | 423 | 76 | 256 | 0.815 |
Methods | Correctly Detected Targets | False Alarms | Missed Targets | Recall Rate | Precision |
---|---|---|---|---|---|
CFAR () | 634 | 1582 | 45 | 0.934 | 0.286 |
CFAR () | 508 | 1243 | 171 | 0.748 | 0.290 |
CFAR () | 372 | 889 | 307 | 0.548 | 0.295 |
Ours | 618 | 17 | 61 | 0.910 | 0.973 |
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Liu, H.; Yan, H.; Hao, J.; Xu, W.; Min, Z.; Zhu, D. Application of Digital Twin Technology in Synthetic Aperture Radar Ground Moving Target Intelligent Detection System. Remote Sens. 2024, 16, 2863. https://doi.org/10.3390/rs16152863
Liu H, Yan H, Hao J, Xu W, Min Z, Zhu D. Application of Digital Twin Technology in Synthetic Aperture Radar Ground Moving Target Intelligent Detection System. Remote Sensing. 2024; 16(15):2863. https://doi.org/10.3390/rs16152863
Chicago/Turabian StyleLiu, Hui, He Yan, Jialin Hao, Wenshuo Xu, Zhou Min, and Daiyin Zhu. 2024. "Application of Digital Twin Technology in Synthetic Aperture Radar Ground Moving Target Intelligent Detection System" Remote Sensing 16, no. 15: 2863. https://doi.org/10.3390/rs16152863