Simulation and experiment of weak multi-target laser detection in complex hydrology
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摘要:
为了探究在近岸复杂水体中激光探测对微弱目标的探测能力,研究水质、目标特征、目标距离对水下激光探测的影响具有重要理论和应用价值。论文建立了水下微弱目标激光探测模型,采用蒙特卡洛仿真验证了不同浊度微弱多目标激光探测性能,模拟了不同距离下微弱目标的激光后向散射回波信号,对多个不同反射系数的目标后向散射回波特性进行了分析。同时设计并研制了灵巧便携式水下微弱目标激光探测系统,进行了实验室及外场湖泊环境下的多目标探测、测距测试验证。在浊度为12.87 NTU的近岸湖泊水域,该系统可在10 m范围内对3~4个直径为80~400 μm的不同低反射系数的混合小目标进行有效探测,平均测量误差为±0.11 m,与理论仿真结果一致。本文研究结果可为蓝绿激光水下多微弱目标探测链路计算、系统设计及参数优化提供参考,可以支撑近海浑浊水体下水下障碍物激光探测工程实践。
Abstract:Investigating the impact of water quality, target characteristics, and target distance on underwater laser detection is crucial to assessing the effectiveness of laser detection for weak targets in complex coastal water bodies. We examine the theoretical and practical significance of understanding these factors in underwater laser detection. In this study, a laser detection model for detecting weak underwater targets is established. Monte Carlo simulation is used to verify the detection performance of weak multi-target laser ranging under different turbidities. The laser backscattering echo signals of weak targets at different distances are simulated, and the backscattering echo characteristics of multiple targets with various reflection coefficients are analyzed. Additionally, a smart and portable laser detection system for detecting weak underwater targets has been designed and developed. Laboratory and field lake environment tests were conducted to detect and range for multi-target. In a near-shore lake with a turbidity of 12.87 NTU, the system can effectively detect 3−4 mixed small target groups. These groups have different low reflection coefficients and diameters varying from 80 to 400 μm, all within a range of 10 meters. The average measurement error is ±0.11 m, which is consistent with the theoretical simulation results. The research results serve as a guide for computing links, designing systems, and optimizing parameters for detecting weak underwater multi-targets using blue and green lasers. Furthermore, the results assist in the engineering practice of detecting underwater obstacles in offshore turbid waters.
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Key words:
- laser detection and ranging /
- weak multi-target /
- complex hydrology /
- Monte Carlo
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目标类型 反射系数 气泡群 0.05 鱼线 0.1 渔网 0.23 多孔礁石 0.36 表 2 不同水质下4种探测目标最远距离统计
Table 2. Statistics of the farthest distances of four detection targets under different water quality conditions
(m) 水质 目标类型 气泡群 鱼线 渔网 多孔礁石 东海台湾海峡 17.2 25.4 30.5 38.8 黄海中部 15.8 22.7 25 32 渤海中部 12.4 19.6 22 26 表 3 不同水质下3种目标探测距离
Table 3. Three target detection distances under different water quality conditions
目标类型 时间/ns 探测距离/m 渔网 47.8 5.5 气泡群 87.0 10 鱼线/多孔礁石 113.1 13 表 4 不同水质下4种目标探测距离
Table 4. Four target detection distances under different water quality conditions
目标类型 时间/ns 探测距离/m 渔网 17.4 2 气泡群 34.8 4 鱼线 69.6 8 多孔礁石 87.0 10 表 5 测试目标尺寸
Table 5. Size of test target
目标类型 尺寸 气泡群 D为70~90 μm 鱼线 D=210 μm 渔网 Φ=2.5 cm;D=280 μm;l=3 m 多孔礁石 L=15 cm;W=13 cm;H=20 cm 表 6 三目标探测距离与实际距离结果对比
Table 6. Comparison of detection distance and actual distance for three targets
目标类型 探测距离/m 时间/ns 实际探测距离/m 平均值/m 相对误差/m 标准差 渔网 5.5 51.2 46.5 48.6 5.894 5.345 5.582 5.607 0.107 0.1548 气泡群 10 91.9 87.85 84.05 10.366 9.909 9.475 9.916 0.084 0.210 鱼线 13 114.8 116.55 115.6 12.955 13.35 13.039 13.15 0.150 0.0538 表 7 四目标探测距离与实际距离结果对比
Table 7. Comparison of detection distance and actual distance for four targets
目标类型 探测距离/m 时间/ns 实际探测距离/m 平均值/m 相对误差/m 标准差 鱼线 2 18.5 18.3 18.05 2.128 2.105 2.075 2.102 0.102 0.03 气泡群 4 34.5 36.2 37.7 3.968 4.163 4.334 4.155 0.155 0.259 渔网 8 70.1 69.3 68.3 8.05 7.970 7.855 7.958 0.042 0.133 多孔礁石 10 91.1 86.5 87.15 10.477 9.940 10.010 10.142 0.142 0.413 -
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