桥梁微多普勒现象的观测与研究

发布时间：2018-04-28 17:04

本文选题：微多普勒 + 一维距离像　；参考：《南京航空航天大学》2017年硕士论文

【摘要】：近年以来,雷达微多普勒研究方兴未艾。随着我国相继建成了一大批大跨度和超大跨度桥梁,桥梁的安全性和耐久性已成为人们关注的热点。研究桥梁的微多普勒现象有助于深入了解桥梁的力学变形和结构,从而计算出模态参数。本论文对桥梁微多普勒效应进行广泛而深入的研究,具体工作包括:基于IFFT变换分析频率步进雷达的回波信号,得到目标的一维距离像。随后推导频率步进雷达在高斯白噪声情况下,对目标物距离进行估计所产生误差的Cramer Rao方差下限。并且深入研究一维距离像的测距精度,主要采用了直接取峰值法、波形分析法、相位差法以及Rife算法。提出了三种改进的Rife算法,实验结果表明,改进的Rife算法综合性能较好。针对含有微多普勒的回波进行目标物体时频信息的特征提取工作,分析出桥梁的本征振动频率。采用Wavelet Transform(WT)对桥梁整体架构的本征频率和阻尼参数进行分析。利用固有模态分解算法进行降噪处理,并且验证了其有效性。最后利用基于EMD分解的HuangHilbert变换分析桥梁的微多普勒效应,得到桥梁的本征振动频率。用到的分析方法有小波变换、经验模态分解(EMD)、Huang-Hilbert变换以及魏格纳变换(WVD)等。利用已有的雷达硬件平台编写基于C语言的数据处理程序,整个数据处理过程包括去冗、分离,最后IFFT形成一维距离像。并且利用多帧一维距离像尖峰处的点比较信号点的相位,从而换算出物体的微小距离改变。
[Abstract]:In recent years, radar micro-Doppler research is in the ascendant. With the construction of a large number of long-span and super-span bridges in China, the safety and durability of the bridges have become the focus of attention. The study of the micro-Doppler phenomenon of the bridge is helpful to understand the mechanical deformation and structure of the bridge and to calculate the modal parameters. In this paper, the micro-Doppler effect of bridge is studied extensively and deeply, including: the echo signal of frequency stepping radar is analyzed based on IFFT transform, and the one-dimensional range profile of the target is obtained. Then the lower bound of Cramer Rao variance is derived for the error of target distance estimation in the case of Gao Si white noise. And the ranging accuracy of one dimensional range profile is studied deeply, which mainly adopts the direct peak value method, waveform analysis method, phase difference method and Rife algorithm. Three improved Rife algorithms are proposed. The experimental results show that the improved Rife algorithm has good synthesis performance. The characteristic extraction of time-frequency information of the target object is carried out for the echo with micro-Doppler, and the intrinsic vibration frequency of the bridge is analyzed. The intrinsic frequency and damping parameters of the whole bridge structure are analyzed by Wavelet Transformator (WTT). The inherent mode decomposition algorithm is used to reduce noise, and its effectiveness is verified. Finally, the HuangHilbert transform based on EMD decomposition is used to analyze the micro-Doppler effect of the bridge, and the intrinsic vibration frequency of the bridge is obtained. The analytical methods used include wavelet transform, empirical mode decomposition EMD-Hilbert transform and WVD transform. The data processing program based on C language is written by using the existing radar hardware platform. The whole data processing process includes de-redundancy, separation, and finally IFFT forms one-dimensional range profile. The phase of the signal point is compared with the point at the peak of the multi-frame one-dimensional range image, and the small distance change of the object can be obtained by comparing the phase of the signal point.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN958

【参考文献】