高分辨成像中的GPS和IMU应用研究

发布时间：2018-01-12 10:19

本文关键词：高分辨成像中的GPS和IMU应用研究　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】：近年来SAR系统向着小型化和高分辨的方向发展,运动误差对成像的影响越来越突出,精确的运动补偿成为高分辨SAR成像工作的重点和难点。GPS和IMU等运动传感器可以直接测量雷达天线相位中心的运动信息,在SAR系统中广泛使用。其中GPS的定位误差不会因时间累积而发散,但是数据率较低,且在非差分模式下定位精度较差;IMU的定位信息具有高精度、高数据率的长处却也存在误差随时间累积的弊端。将GPS和IMU数据融合成为高分辨SAR运动补偿的主要研究方向。本文主要研究了使用GPS和IMU单元——加速度计进行运动补偿实现高分辨SAR成像的方法。为完成数据融合的目的,先后对结合运动补偿的成像算法、GPS和加速度计的数据预处理以及插值的融合方法进行了探索和研究。具体的研究内容和取得的研究成果如下:(1)对FMCW SAR回波和运动误差建模,分析高分辨SAR对运动补偿的精度要求;研究精确聚焦的RMA成像算法,在已有改进算法的基础上,增加基于回波数据的自聚焦补偿剩余相位误差,并估计运动参数补偿距离空变误差,提出改进的RMA算法作为运动补偿实现的算法平台。(2)研究了GPS和加速度计的数据预处理流程,在此基础上分析了GPS和加速度计定位的性能,为后续研究GPS和加速度计数据融合方法提供技术支撑。分析运动状态下重力加速度分量对定位的巨大影响,研究了运动中加速度计重力分量的补偿方法,提出了利用GPS信息估计重力加速度分量的方法。(3)提出了两种加速度计与GPS数据融合的插值方法,在理论分析基础上对比实测定位数据比较了两种插值融合方法的效果。最后将两种数据融合方法用于运动补偿中,与单独使用GPS的运动补偿进行对比,验证了基于位置插值的融合方法在精确运动补偿中的有效性。
[Abstract]:In recent years, SAR system has been developing towards miniaturization and high resolution. The effect of motion error on imaging is becoming more and more prominent. Precise motion compensation has become the focus and difficulty of high-resolution SAR imaging. The motion sensors such as GPS and IMU can directly measure the motion information of the phase center of radar antenna. It is widely used in SAR system, in which the positioning error of GPS does not diverge due to time accumulation, but the data rate is low, and the positioning accuracy is poor in the non-differential mode. The location information of IMU has high accuracy. The advantage of high data rate also has the disadvantage of error accumulation over time. Fusion of GPS and IMU data is the main research direction of high resolution SAR motion compensation. This paper mainly studies the use of GPS and IMU. The method of realizing high-resolution SAR imaging by motion compensation with element-accelerometer, for the purpose of data fusion. The imaging algorithm combined with motion compensation has been studied. The data preprocessing of GPS and accelerometer and the fusion method of interpolation are explored and studied. The specific research contents and results obtained are as follows: 1). The FMCW SAR echo and motion error are modeled. The requirement of high resolution SAR for motion compensation is analyzed. The RMA imaging algorithm with precise focus is studied. Based on the existing improved algorithm, the residual phase error is compensated by self-focusing based on echo data, and the motion parameters are estimated to compensate the range space variation error. An improved RMA algorithm is proposed as an algorithm platform to realize motion compensation. The data preprocessing flow of GPS and accelerometer is studied. Based on this, the performance of GPS and accelerometer positioning is analyzed. It provides technical support for further research on GPS and accelerometer data fusion method, analyzes the great influence of gravity acceleration component on positioning under moving state, and studies the compensation method of accelerometer gravity component in motion. A method of estimating the acceleration component of gravity using GPS information is proposed. Two interpolation methods for fusion of accelerometers and GPS data are proposed. On the basis of theoretical analysis, the effects of two interpolation fusion methods are compared by comparing the measured location data. Finally, the two data fusion methods are used in motion compensation, and compared with the motion compensation using GPS alone. The validity of the fusion method based on position interpolation in accurate motion compensation is verified.
【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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