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He Qigong, Jia Xiaodong. Target detection technique of laser and millimeter wave dual-mode fused proximity detection[J]. Infrared and Laser Engineering, 2021, 50(7): 20200361. doi: 10.3788/IRLA20200361
Citation: He Qigong, Jia Xiaodong. Target detection technique of laser and millimeter wave dual-mode fused proximity detection[J]. Infrared and Laser Engineering, 2021, 50(7): 20200361. doi: 10.3788/IRLA20200361

Target detection technique of laser and millimeter wave dual-mode fused proximity detection

doi: 10.3788/IRLA20200361
  • Received Date: 2020-12-21
  • Rev Recd Date: 2021-01-18
  • Publish Date: 2021-07-25
  • Aiming at the problems of complex background and strong environment adaptability of fuze system, a short-range detection method based on laser and millimeter wave fusion for the application background of sea target orientation recognition and anti-jamming of new generation anti-ship missile was proposed in this paper. Firstly, the shortcomings of single-mode detection system were introduced from the applicaion status of laser and millimeter wave in fuze. In view of this deficiency, a compound detection scheme based on the dual-mode fusion was proposed, and the detection system structure, accurate time identification algorithm of pulsed laser in dynamic scene and fusion target detection method were studied. In this method, the consistency and stability of laser detection performance in complex scenes could be achieved. And by introducing the distance information obtained from laser detection system into millimeter wave target detection algorithm simultaneously, the efficiency and reliability of the algorithm were effectively improved. Through theoretical simulation analysis, the results show that the method in this paper can make up for the shortcomings of single detection system in anti-jamming, and effectively improve the efficiency and reliability of target detection, which can provide reference for the subsequent anti-jamming system design of proximity fuze.
  • [1] Long Teng, Liang Zhennan, Liu Quanhua. Advanced technology of high-resolution radar: target detection, tracking, imaging, and recognition [J]. Science China(Information Sciences), 2019, 62: 40301.
    [2] Song Chuang, Jiang Peng, Duan Lei, et al. Application research of new photoelectric detection technology on precision guided weapons(Invited) [J]. Infrared and Laser Engineering, 2020, 49(6): 20201015. (in Chinese) doi:  10.3788/IRLA20201015
    [3] Su Zhizhou, Wu Zibo. Overview of USA long range precision strike [J]. Aerodynamic Missile Journal, 2019(9): 10-15. (in Chinese)
    [4] Zuo Wei, Zhou Bohua, Li Wenzhu. Analysis of development of multi-mode and compound precision guidance technology [J]. Air & Space Defense, 2019, 2(3): 44-52. (in Chinese) doi:  10.3969/j.issn.2096-4641.2019.03.008
    [5] Vk Arora. Proximity Fuzes: Theory and Techniques[M]. India: Ministry of Defence, Defence Research & Development Organisation, 2010.
    [6] Zhang He. Fuze and environment [J]. Journal of Detection & Control, 2019, 41(1): 1-5. (in Chinese)
    [7] Gao Yejun. Analysis of the research status and development process of fuze system in foreign countries [J]. Guidance & Fuze, 2018, 39(1): 1-5. (in Chinese)
    [8] Chen Huimin, Liu Weibo, Gu Jian, et al. Design of FMCW laser fuze detecting system [J]. Infrared and Laser Engineering, 2017, 46(12): 1206004. (in Chinese) doi:  10.3788/IRLA201746.1206004
    [9] Dao Xinyu, Gao Min. Development status and key technology of millimeter wave proximity fuze [J]. Aerodynamic Missile Journal, 2018(5): 86-90. (in Chinese)
    [10] Yang Yi. Design and implementation of signal processor for FMCW millimeter radar fuze [J]. Application of Integrated Circuits, 2010, 36(10): 53-56. (in Chinese) doi:  10.3969/j.issn.0258-7998.2010.10.020
    [11] Wang Huihui, Fu Xuebin, Zhang Ke. Digital signal processing of millimeter wave fuze [J]. Journal of Detection & Control, 2014, 36(5): 34-37, 42. (in Chinese)
    [12] Han Yibo, Yang Xinfeng, Teng Shuhua, et al. Detection of laser and infrared fusion target [J]. Infrared and Laser Engineering, 2018, 47(8): 0804005. (in Chinese) doi:  10.3788/IRLA201847.0804005
    [13] Qi Yanbin, Tan Wen, Ma Ruofei, et al. The analysis and implementation of millimeter-wave LFMCW fuse[C]//2016 IEEE International Conference on Ubiquitous Wireless Broadband (ICUWB), 2016: 1-3.
    [14] 段亚博. 调频连续波体制激光与无线电复合引信探测技术研究[D]. 北京: 北京理工大学, 2017.

    Duan Yabo. Research on detection technology of frequency modulated continuous-wave(FMCW) laser and radio combination fuze[D]. Beijing: Beijing Institute of Technology, 2017. (in chinese)
    [15] Zhuang Jiaxin, Jiao Nong, Yin Fei. Research on Application of MMW Radar and Lidar in MASS [J]. Ship Engineering, 2019, 41(11): 79-82, 119. (in Chinese)
    [16] 崔巍杰. 毫米波和激光雷达数据融合的SLAM算法研究[D]. 成都: 电子科技大学, 2019.

    Cui Weijie. SLAM algorithm based on millimeter wave radar and lidar data fusion[D]. Chengdu: University of Electronic Science and Technology of China, 2019. (in Chinese)
    [17] Wang Rui. Compound guided system with active laser imaging and passive infrared imaging [J]. Chinese Optics, 2013, 6(4): 536-543. (in Chinese)
    [18] Lu Changping, Jiang Lu, Liu Yuelong. Technology of signal processing for laser/radio compound fuze [J]. Guidance & Fuze, 2017, 38(3): 1-3, 9. (in Chinese) doi:  10.3969/j.issn.1671-0576.2017.03.001
    [19] Wu Yu, Zhou Muchun, Zhao Qi, et al. Threshold-peak dual-channel time discrimination method for pulse laser ranging [J]. Infrared and Laser Engineering, 2019, 48(6): 0606002. (in Chinese) doi:  10.3788/IRLA201948.0606002
    [20] Yang Binhe, Cai Yindi, Wen Zhixiang, et al. Automatic compensation method for beam drift in long-distance laser measurement [J]. Optics and Precision Engineering, 2020, 28(11): 2393-2402. (in Chinese)
    [21] 牛文博. 毫米波近炸引信信号处理技术研究[D]. 西安: 西安电子科技大学, 2009.

    Niu Wenbo. Study on the signal processing techniques of millimeter wave proximity fuze[D]. Xi'an: Xidian University, 2009. (in Chinese)
    [22] 闫俊伟. LFMCW雷达多目标检测算法研究与实现[D]. 成都: 电子科技大学, 2016.

    Yan Junwei. Research and implementation of LFMCW radar multi-target detection algorithm[D]. Chengdu: University of Electronic Science and Technology of China, 2016. (in Chinese)
    [23] 刘闯. 对称三角LFMCW雷达目标检测方法的研究[D]. 西安: 西安电子科技大学, 2005.

    Liu Chuang. Research on moving target detection using symmetrical trigonal LFMCW radar[D]. Xi'an: Xidian University, 2005. (in Chinese)
    [24] Su Zhimou, Jian Jinlei, Ren Hongbin, et al. Design of guidance integrated fuzing based on millimeter wave technology [J]. Aerodynamic Missile Journal, 2012(3): 81-85. (in Chinese)
    [25] Jiang Jingqun, Jian Jinlei, Hu Hongyu. Antijamming signal processing research of pulse Doppler fuze [J]. Guidance & Fuze, 2008, 29(4): 32-37. (in Chinese) doi:  10.3969/j.issn.1671-0576.2008.04.006
    [26] Zhu Fan, Li Yingxian, Tan Jiubin. Design of high-accuracy laser beam collimation system [J]. Optics and Precision Engineering, 2020, 28(4): 817-826. (in Chinese)
    [27] Deng Wantao, Zhao Gang, Zhang Mao, et al. Design of optical device with co-aperture for high energy laser system [J]. Chinese Optics, 2020, 13(1): 165-178. (in Chinese) doi:  10.3788/co.20201301.0165
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Target detection technique of laser and millimeter wave dual-mode fused proximity detection

doi: 10.3788/IRLA20200361
  • 1. School of Electronics and Information Engineering, Beihang University, Beijing 100191, China
  • 2. Tianjin Jinhang Institute of Technical Physics, Tianjin 300381, China

Abstract: Aiming at the problems of complex background and strong environment adaptability of fuze system, a short-range detection method based on laser and millimeter wave fusion for the application background of sea target orientation recognition and anti-jamming of new generation anti-ship missile was proposed in this paper. Firstly, the shortcomings of single-mode detection system were introduced from the applicaion status of laser and millimeter wave in fuze. In view of this deficiency, a compound detection scheme based on the dual-mode fusion was proposed, and the detection system structure, accurate time identification algorithm of pulsed laser in dynamic scene and fusion target detection method were studied. In this method, the consistency and stability of laser detection performance in complex scenes could be achieved. And by introducing the distance information obtained from laser detection system into millimeter wave target detection algorithm simultaneously, the efficiency and reliability of the algorithm were effectively improved. Through theoretical simulation analysis, the results show that the method in this paper can make up for the shortcomings of single detection system in anti-jamming, and effectively improve the efficiency and reliability of target detection, which can provide reference for the subsequent anti-jamming system design of proximity fuze.

  • 随着现代战争模式和武器系统的不断发展,研究高效费比灵巧弹药,实现对特定目标的精确打击与高效毁伤已成为当下武器系统发展最为活跃的领域之一,受到了各国研究人员的广泛重视[1-4]。近炸引信作为武器系统攻击末端精确毁伤的关键设备,利用环境信息和目标信息,在预定条件下控制战斗部在相对于目标最有利的位置或时机起爆或引爆战斗部装药,在应对目标的机动性,最大限度地发挥武器的作战性能,提高引战配合效率方面发挥着重要的作用[5-6]。其探测精度和可靠性决定了武器系统是否能够按照预定策略对目标实现精确毁伤[7]

    战争环境日益复杂,对抗愈加激烈,使得引信抗干扰的需求不断被强化。尽管毫米波和激光有诸多优势,但是单模探测的局限性,始终无法彻底解决[8-11]。因此,基于单模探测的特点,尤其是结合毫米波抗自然干扰的特性和激光抗电磁干扰的特性,开展复合探测体制研究成为引信抗干扰能力提升的突破点[12-14]。庄加兴等利用激光/毫米波组合特性开展了无人船舶近距离目标运动态势感知研究[15]。崔巍杰在激光雷达探测基础上结合毫米波雷达,通过对毫米波雷达和激光雷达数据特征的研究,实现了融合导航定位算法[16]。王锐利用激光主动三维成像技术配合被动红外成像技术共同工作的复合导引体制,用于提升地对地导弹的作战效能及对于隐身目标的识别能力[17]。在复合引信探索方面,陆长平等较早地开展了激光/无线电复合引信研究,在激光引信中增加无线电探测系统组成复合引信,并通过信息处理算法对目标进行识别,提高引信抗干扰能力[18]

    文中以新一代反舰导弹海面目标方位识别和抗干扰为应用背景,从增强引信环境适应性的角度出发,在传统激光引信基础上,提出了基于激光与毫米波的复合探测方案,将激光引信测得的弹目距离信息引入到毫米波目标检测算法中,研究适用于复合探测系统的目标检测方法。通过理论仿真,对文中提出的检测方法进行了验证,结果表明该方法能够弥补单一探测体制抗干扰方面的不足,有效提高目标探测的效率和可靠性。

  • 文中采用基于飞行时间测量原理的窄脉冲激光测距方法实现激光近炸引信探测[19-20]。由于激光在空气中的传播速度基本不变,通过测量激光到目标往返所用时间就可计算到目标的距离。由信号处理电路产生的触发信号驱动激光收发组件发射激光脉冲,在目标物体处折返为回波,一部分被激光接收电路接收并转换为电信号,经模拟端滤波整形后进入高速模拟数字转换器(ADC)采集电路进行模数转换并将采样结果送给数字基带部分,经过处理得到激光脉冲往返目标间的飞行时间,进而解算出目标的距离。设测量目标距离为$R$,激光脉冲往返经过的时间,即基准脉冲与回波脉冲之间的时间间隔为$t$,则$R = ct{\rm{/2}}$,式中,$c$为光速。

  • 通常将30~300 GHz的频域称为毫米波(波长为1~10 mm)。为减小大气衰减和吸收的影响,通常使用35 GHz、94 GHz、140 GHz和220 GHz四个主要大气窗口中可利用的16 GHz、23 GHz、26 GHz和70 GHz带宽进行探测[21]。文中采用24 GHz对称三角线性调频连续波(Symmetrical Triangular Linear Frequency Modulation Continuous Wave, ST-LFMCW)信号完成近程实时精确测距。其信号发射频率按图1所示规律变化。

    Figure 1.  Principle of triangular frequency modulation continuous wave ranging

    根据毫米波测距、测速理论[22-25],可得:

    因此,只要对差拍信号进行采样,再利用FFT频域分析得到差拍信号在上下扫频段的频率,就可以求得目标的距离和运动的径向速度$v$。由于采样、测频等误差的存在,这种方法会产生固定误差$\Delta R$,由公式(1)可得$\Delta R$表达式为:

    可见,固定误差$\Delta R$与频偏$\Delta {f_{{m}}}$成反比,而与距离${R_0}$及工作频率${f_0}$无关。为减小这项误差,使$\Delta {f_{{m}}}$加大到数十兆赫兹以上,而通常的工作频率则选为数百兆赫兹到数吉赫兹。

  • 笔者所提方案利用毫米波抗自然干扰和激光抗电磁干扰的特性[21-22],通过设计适当的信息融合算法,实现引信可靠工作。探测系统模型基于可编程逻辑门阵列(FPGA)完成数字化结构设计,主要包含复合探测时序控制模块、一体化收发光学模块、激光收发组件、微波收发组件、ADC高速采集及预存储模块、激光回波信号处理模块、毫米波回波信号处理模块、信息融合算法处理模块、天线及环形隔离器模块等,如图2所示。考虑到海面目标方位识别与抗干扰的应用背景,探测系统采用前下视探测方案,其中,激光探测采用三路窄脉冲激光分时收发方案,各路探测视场角均为${60^ \circ }$,中路分别与左、右边路探测视场重合${15^ \circ }$,以便于后续进行抗干扰算法设计;毫米波采用单路ST-LFMCW体制,载波频率24 GHz,毫米波探测视场与三路激光探测视场重叠,覆盖前下视方向${150^ \circ }$空间。

    Figure 2.  Laser/millimeter wave composite detection system model

    系统在复合时序控制下,周期地产生触发信号,控制激光收发组件和微波收发组件发射相应的探测信号;同步产生数字选通信号,切换ADC高速采集及预存储模块前端的模拟输入通道及乒乓FIFO后端的处理通道,保持前端模拟输入与后端数字处理的同步。

  • 探测装置开机后,FPGA在启动探测指令控制下周期地产生四路触发信号,激励微波收发组件产生ST-LFMCW信号、激光收发组件产生三路激光发射脉冲。复合控制时序如图3所示。

    Figure 3.  Schematic diagram of emission control sequence of laser/millimeter wave composite detection

    四个探测支路分时工作,第一路激励信号激励微波收发组件产生ST-LFMCW信号,经过发射通道后通过天线进行发射;回波信号经天线接收后由接收通道处理得到差拍信号;差拍信号经ADC采样后得到数字化的差拍信号,并在FPGA内部对该数字差拍信号进行处理,提取目标信息。在第二、三、四路激励信号激励下,激光收发组件产生宽度约30 ns的激光脉冲,经一体化收发光学模块射向目标空间。

  • 为减小激光收发光学体积,方案采用一体化收发光学前下视收发视场设计[26-27]。毫米波采用收发天线分置结构,隔离度好,灵敏度高,动态范围大,短距离工作性能好,如图4所示。

    Figure 4.  Schematic diagram of detection field of view distribution of laser/millimeter wave composite detection system

  • 为简化硬件设计,系统采用统一的250 MHz采样频率。但是在实际处理过程中,为提高激光测距精度,需在250 MHz物理采样基础上通过插值将采样率提升至2 GHz,降低因采样误差引入的测距误差。对于毫米波探测,在作用距离范围内的差拍信号频率变化不大于50 MHz,按照奈奎斯特采样定理,大于两倍带宽采样即可无失真地恢复原始信号中的信息。因此,在250 MHz物理采样基础上通过抽取将采样率降至125 MHz,以减小处理过程中的运算量,节省计算资源。考虑到系统处理的实时性及资源消耗,采用乒乓FIFO的预存储策略,两路FIFO分时进行存取操作,设计模型如图5所示。

    Figure 5.  Schematic diagram of AD acquisition and pre-storage model

  • 激光回波信号设计时,对基准信号和激光回波脉冲信号进行了合路,形成了正负脉冲统一采样的回波波形,一方面避免因基准信号漂移导致的测距超差问题,另一方面便于信号处理过程中对基准信号与回波脉冲信号的同步处理。激光回波信号处理流程如图6所示,首先根据设置的基点,查找脉冲的最大幅度坐标;其次确定脉冲的半峰值,并以此分别查找脉冲前后边沿对应的采样区间;然后提取脉冲半峰值所对应的采样时刻,进而提取脉冲的各特征参数。由于激光探测距离动态范围较大,激光回波在近区存在因饱和导致脉冲展宽的现象,影响测距精度。因此,在提取激光回波参数后需根据脉冲宽度对测距结果进行校正,抵消因脉冲展宽对测距精度的影响,实现精确测距。

    Figure 6.  Processing flow diagram of laser detection echo signal

  • 与激光探测过程相似,毫米波探测期间,发射模块在激励信号激励下发射ST-LFMCW信号;接收模块将接收的高频信号与发射信号进行混频后输出相应的差拍信号。由于作用距离有限,回波差拍信号的带宽在1 kHz~50 MHz范围内,为兼顾激光测距系统采样的需求,采样频率设置为250 MHz,大于毫米波探测的实际需求,综合考虑运算量等因素,毫米波回波信号处理单元需对差拍信号进行预处理后,再进行${N_{FFT}}$点FFT,提取差拍信号的多普勒频率,进而得到装置与目标间的距离和目标的相对运动速度信息。毫米波差拍信号处理流程如图7所示。

    假设存在${N_T}$个目标,经过加窗FFT后,分别得到上下扫频段内差拍信号的$M$$N$个谱峰$f_{bi}^{\rm{ + }}$$f_{bj}^{\rm{ - }}$,其中,$0 \leqslant i \leqslant M$$0 \leqslant j \leqslant N$。由于存在距离速度耦合效应,目标的频谱峰值可能重合,$M$$N$的个数可能小于实际目标个数,即$M,N \leqslant {N_T}$。根据得到的差拍信号峰值,结合上述公式,可得到$M \times N$维的距离速度组合矩阵:

    Figure 7.  Processing flow diagram of millimeter wave echo signal

    由上可知,多目标情况下ST-LFMCW解算会出现距离速度模糊,需要对频谱进行对消、去虚警等操作,利用容差函数剔除虚假目标,保留真实目标的频谱信息,并进一步提取真实目标的距离、速度信息。此方法存在的问题是相似目标配对紊乱,计算复杂,实时性差。通过引入激光测距信息,进行联合解模糊,能够大大减小运算量,提升处理的实时性,主要实现步骤如下:

    (1)分别对ST-LFMCW信号上、下扫频段内的差拍信号进行采样并进行加窗FFT,提取FFT的频谱峰值${F_u}(m)$${F_d}(n)$

    (2)对${F_u}(m)$${F_d}(n)$进行对消处理,抑制固定杂波,并进行恒虚警处理,得到$F_u'(m)$$F_d'(n)$

    (3)对$F_u'(m)$$F_d'(n)$进行区域滑窗检测,分别得到$M$$N$个谱峰$f_{bi}^{\rm{ + }}$$f_{bj}^{\rm{ - }}$,其中,$i$$j$为整数,且$ M$$ N\leqslant {N}_{T}$

    (4)根据公式(4),得到距离速度矩阵$\left( {{R_i},{v_j}} \right)$

    (5)解算激光探测数据,提取目标距离向量$R_i^L$

    (6)设置适当的容差值,对距离速度矩阵中的目标进行匹配,对距离速度矩阵解模糊,剔除虚假目标,得到真实目标的距离、速度参数。

  • 提取到目标特征信息(距离、速度等)后,需要利用相关的判别算法,分别进行目标识别,判断是否有目标存在;然后综合激光和毫米波目标识别结果对探测结果进行决策,判断是否有目标存在于探测视场。判决逻辑如下:

    (1)当毫米波和激光均检测到有效目标,则判定目标存在。此时,若激光测距值大于设定的盲区阈值,则以激光测距为准;否则,以毫米波测距值为准。当测距结果小于等于装订的起爆距离门限,则输出有效的启动信号;

    (2)当毫米波检测到目标,而激光未检测到目标,则判定存在电磁干扰。此时,以激光测距值为准,当测距结果小于等于装订的起爆距离门限,则输出有效的启动信号;

    (3)当毫米波未检测到目标,而激光检测到目标,且三路激光均收到回波信号,则判定存在自然环境干扰。此时,以毫米波测距值为准,当测距结果小于等于装订的起爆距离门限,则输出有效的启动信号;

    (4)当毫米波和激光均未检测到有效的目标,则判定目标不存在。此时,不输出有效的启动信号。具体的融合判决流程如图8所示。

    Figure 8.  Flow diagram of fusion decision

  • 为验证算法的有效性,基于在研探测设备采集的激光回波数据,通过理论计算进行了仿真分析。仿真试验条件如下:激光探测盲区为1.25 m;毫米波载频${f_{{{t}} 0}}$设置为24 GHz,信号带宽$B$为500 MHz,ST-LFMCW信号频率调制周期${T_{{m}}}$设计为50 ${\rm{{\text{μ}} }}\rm s$,调频斜率$k$${\rm{2}} \times $$ {10^{1{\rm{3}}}}\;{\rm{ Hz/s}}$。因此,最大作用距离35 m往返时间内频率变化$\Delta f$约为${\rm{4}}{\rm{.667\;MHz}}$,采样频率设置为250 MHz。为避免三角波信号线性度引起的误差,至少需要采样一个三角波周期内(50 ${\rm{{\text{μ}} }}{\rm s}$)的数据,采样点数至少为12500点。由测距误差与测频精度关系可知,要达到0.5 m的测距精度,测频精度$\Delta {f_{{{bav}}}}$需小于${\rm{66}}{\rm{.667\;kHz}}$,进而可以得出最小FFT点数${N_{{\rm{min}}}}$为3750。系统中取4 096点FFT,测距精度$\Delta R$约为$0.{\rm{457\;8\;m}}$,满足系统设计要求。

    根据上述设计参数,结合在研设备对作用距离和多目标探测能力的需求,从文中融合处理算法角度出发,假设存在5个目标(如图9所示),距离和速度组合分别为(30,18)、(18.9,15.2)、(6.5,−12.857)、(26.3,0)、(8.0,8.2),其中目标4为固定杂波。

    Figure 9.  Matrix distribution diagram of simulation target distance and velocity

    单周期内对差拍信号进行加窗FFT运算,得到上、下扫频段内距离谱如图10所示。

    Figure 10.  Schematic diagram of range spectrum in up and down sweep frequency band of echo beat signal of target in single cycle

    按照步骤(4)得到$M \times N$距离速度组合矩阵如下:

    上下扫频段内距离谱解算的距离速度矩阵分布示意图见图11

    Figure 11.  Distribution diagram of range velocity matrix of the range spectrum solution in the up and down sweep frequency bands

    为便于分析,仅对中路激光探测数据进行仿真。假设$L$个目标在位于引信前方视场不同距离点上,系统以4.15 kHz重频激光脉冲对目标进行探测,采集的中路激光回波信号波形如图12所示。通过解算正脉冲信号上升沿相对于负脉冲信号下降沿之间的采样间隔,即可得到$L$个目标的距离分别为:

    Figure 12.  Schematic diagram of target echo signal collected by laser detection system

    经目标调制后的激光回波在近区存在因饱和导致脉冲展宽的现象使回波脉冲在不同距离下发生畸变,需要根据激光回波能量变化情况对激光测距结果进行修正。结合笔者所在团队多年来对具有不同反射率的目标进行探测试验采集的激光回波脉冲数据,激光回波脉冲宽度与目标距离之间变化关系如图13所示,利用该规律对解算的目标距离进行修正,修正前后的激光测距精度如图14所示,可得实际目标距离为:

    Figure 13.  Energy variation curves of laser echo at different distances

    Figure 14.  Schematic diagram of laser ranging accuracy at different distances

    由以上分析可见,激光测距结果均大于设定的盲区阈值,测得的目标距离均为有效值;而毫米波探测由于存在差拍信号多普勒模糊问题,产生了诸多的“假目标”。按照图8所示流程,一方面,在激光和毫米波均探测到目标且激光探测结果有效的情况下,以激光测距结果作为启动信号判据输入;另一方面,为进一步提高目标探测的可靠性,通过将毫米波探测的结果与激光测距结果进行匹配,剔除因模糊引起的“假目标”,而保留下来的即为可靠的探测目标。

    考虑到激光与毫米波探测角度差引起的测距偏差,按照系统距离分辨率的2~5倍设计容差,通过$M \times N \times L$次匹配判别,即可提取毫米波探测的目标信息和激光探测的目标距离信息分别为:$ ({R_i},{v_j}) = \left[ {\begin{array}{*{20}{c}} {({\rm{30}}{\rm{.002\;4}},{\rm{15}}{\rm{.7}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})} \\ {({\rm{0}},{\rm{0}})}&{({\rm{18}}{\rm{.899\;6}},15)}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})} \\ {({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{6}}{\rm{.499}},{\rm{ - 11}}{\rm{.8}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})} \\ {({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})} \\ {({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{0}},{\rm{0}})}&{({\rm{8}}{\rm{.008\;4}},11.4)} \end{array}} \right]$$ {R}^{L}=\left[\begin{array}{cccc}6.51,& 7.965,& \rm{18}\rm{.832},& 29.839\end{array}\right]$

    由此可见,实际应用中,由于干扰目标的存在,单模探测系统在不同距离可能产生多余探测结果,引起虚警;通过文中设计的匹配算法,能够有效过滤干扰目标,弥补单模探测抗干扰方面的不足。相对于传统的单模探测系统,在滤除干扰的同时大大提高解算效率。

  • 文中充分利用毫米波和激光的探测优势,通过采用一体化的光学设计解决了双模探测的体积问题;通过插值与抽取技术的应用,兼顾了双模采样率分化问题,降低系统设计的难度,提高了系统对不同应用场景的适应性;通过将激光引信测得的弹目距离信息引入到毫米波目标检测算法中,提高了毫米波目标检测过程中解模糊的效率。理论仿真结果表明,该系统能够弥补单一探测体制在抗干扰方面的不足,有效提高目标探测的效率和可靠性,具有良好的环境适应性。实际使用中,为提升系统的可靠性和效率,未来还需要深入研究更加智能化的融合算法,提升双模融合深度。

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