穿墙三维成像技术研究

发布时间：2018-01-15 09:44

本文关键词：穿墙三维成像技术研究　出处：《国防科学技术大学》2014年硕士论文　论文类型：学位论文

【摘要】：穿墙成像雷达(Through-Wall Imaging Radar,TWIR)利用低频电磁波的穿透特性,对隐蔽在建筑物之内的目标进行探测、定位和成像等状态分析,大大提高了城区作战能力、反恐斗争以及灾难救援时人员搜救能力,成为了近些年来的研究热点。由于二维成像是对真实三维空间二维投影的结果,成像结果不可避免地会出现定位误差、阴影效应以及空间模糊等现象,获取目标场景的三维信息成为了迫切需要。本文围绕穿墙三维成像问题,对穿墙三维成像基础、穿墙二维多输入多输出(Multiple Input Multiple Output,MIMO)阵列设计以及介质穿透三维图像快速重建三个主要问题进行了分析研究。首先分析了三维成像中目标空间、数据空间和图像空间与成像过程的对应关系,建立了步进频信号体制的三维回波模型;具体分析了三种常见时频域三维成像算法,并针对介质穿透成像的特点选取时域后向投影(Back Projection,BP)算法作为基本穿墙成像算法;通过角度旋转变换方法将二维空间中的传输路径的求解方法应用于介质穿透三维成像中,建立了介质穿透三维成像模型。其次在分析宽带稀疏阵列栅瓣特性和二维面阵中高度向、方位向阵元分布对相应方向阵列性能的相互影响的基础上,利用虚拟等效阵列的思想,提出一种基于子阵划分的普适性二维平面MIMO阵列设计方法。该方法可得到多种典型MIMO阵列架构,利用子阵划分信息可从中选择出具有最小物理尺寸的MIMO阵列。仿真实例验证了该设计方法,取得了较好结果。最后分析了二维因式分解快速后向投影(Fast Factorized Back Projection,FFBP)算法的基本原理、距离误差以及成像效率等问题;建立了适用于FFBP算法的方位、高度向等效的三维极坐标系,将二维FFBP算法推广至三维成像,推导出适于介质穿透的三维FFBP算法,并对介质穿透条件下传统BP算法与三维FFBP算法性能以及成像结果进行了对比分析,证明了三维FFBP的有效性和鲁棒性。
[Abstract]:Through-Wall Imaging Radarr (TWIR) detects targets hidden in buildings by using the penetrating characteristics of low-frequency electromagnetic waves. State analysis, such as positioning and imaging, has greatly improved the city's combat capability, the ability to search and rescue people in the fight against terrorism and in disaster relief. In recent years, two-dimensional imaging is the result of 2D projection of real three-dimensional space, which inevitably leads to localization error, shadow effect and spatial blurring. It is an urgent need to obtain 3D information of target scene. Two dimensional multiple Input Multiple Output through the wall. The three main problems of MIMO-array design and fast reconstruction of media penetrating 3D image are analyzed. Firstly, the target space in 3D imaging is analyzed. The relationship between the data space and the image space and the imaging process, the three-dimensional echo model of the stepping frequency signal system is established. Three common 3D imaging algorithms in time-frequency domain are analyzed in detail. According to the characteristics of dielectric penetrating imaging, the time-domain backward projection back Projection is selected. BPalgorithm is used as the basic imaging algorithm. The method of solving the transmission path in two-dimensional space is applied to the three-dimensional imaging of media penetration by the method of angular rotation transformation. The 3D imaging model of dielectric penetration is established. Secondly, based on the analysis of the characteristics of the wide band sparse array gate lobe and the interaction between the height and the azimuth distribution of the array in two dimensional plane array, the performance of the array in the corresponding direction is analyzed. Based on the idea of virtual equivalent array, a universal two-dimensional planar MIMO array design method based on subarray partition is proposed, which can be used to obtain several typical MIMO array architectures. The MIMO array with the minimum physical size can be selected from the subarray partition information. The simulation example verifies the design method. Good results have been obtained. Finally, fast Factorized Back Projection with fast backward projection of 2-D factorization is analyzed. The basic principle, range error and imaging efficiency of FFBP algorithm are discussed. The azimuth and height equivalent three-dimensional polar coordinate system suitable for FFBP algorithm is established. The two-dimensional FFBP algorithm is extended to 3D imaging and a three-dimensional FFBP algorithm suitable for medium penetration is derived. The performance and imaging results of traditional BP algorithm and 3D FFBP algorithm under the condition of medium penetration are compared and analyzed. The effectiveness and robustness of 3D FFBP are proved.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.52

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