偏振光导航

本文简单的介绍了偏振光导航的发展背景、偏振光导航的基本原理以及偏振光导航的发展历程,同时提出了偏振光导航需要解决的问题。     

基于惯性/偏振光/光流的六足步行机器人自主导航方法研究

针对惯性/卫星组合导航系统易受干扰或自主性不足等问题，引入偏振光传感器和光流传感器，分别建立航向角和速度量测方程，以辅助惯性导航系统，提出了一种基于惯性/偏振光/光流的自主导航方法。同时，为实现惯性传感器、偏振光传感器和光流传感器等多传感器的融合，设计了无迹Kalman滤波器。为验证该方法的有效性，以六足步行机器人为对象开展仿真和实验验证。结果表明，在没有卫星信号源的情况下，仅依靠机器人自身感知，可实现较高精度的机器人位姿估计，实现了不依赖于卫星导航信号的自主导航，提升了导航系统的自主性。     

一种用于仿生导航无人机航姿求解的混合滤波方法

针对现有组合导航系统易被干扰欺骗以及姿态求解精度不足的问题，设计了惯性测量单元(IMU)与偏振光传感器组成的航姿参考系统(AHRS)。同时，考虑到传统的姿态求解方法精度不高，提出了一种用于仿生导航无人机航姿求解的混合滤波方法。将Mahony滤波后的姿态值作为系统观测量，再结合扩展卡尔曼滤波(EKF)实现传感器数据的深层融合，以获得高精度的姿态角信息。实验结果表明：在静态环境下采用混合滤波方法求解的姿态值能有效滤除偏振光传感器和加速度计内部噪声干扰，其稳定性明显优于两种方法各自求解时的情况；在动态实验中该方法能有效抑制单独采用Mahony滤波时存在的超调问题，表现出更高的动态解算精度，从而为偏振光组合导航系统提供了更精确的姿态估计信息。     

面向地面无人平台的仿生偏振光定向算法

仿生偏振光定向为地面无人平台提供了一种新型的低成本、小型化定向方式。设计了一种基于微阵列式偏振光栅的仿生光罗盘,实现了一种加权平均的偏振光定向算法,分析了大气偏振模式误差、太阳位置误差、偏振光传感器误差和水平姿态角误差等因素对航向角估计精度的影响。实验结果表明,动态车载条件下定向误差小于0.5°。     

计算机三维成像系统程序设计

本文介绍了计算机三维成像系统的结构及工作原理，并着重讨论计算机三维成像系统互补色体视图，偏振光体视图及随机点体视图的程序设计方法。     

多云天气条件下的大气偏振光定向方法

针对多云天气情况下传统的偏振光定向算法精度下降的问题,提出了一种用于多云天气条件下的大气偏振光定向方法。首先,根据已知信息建立任意一个像素点的偏振光定向模型;然后,基于上一步得到的定向模型,利用随机抽样一致算法筛选出符合要求的内点,并根据筛选出的这些内点得出最符合要求的定向模型;最后,利用选取出的最优的定向模型解算出航向角,实现了基于大气偏振光的定向。通过实际数据证明了该方法的有效性,解算出的航向角误差在少云情况下小于0.5°、多云情况下小于1°。     

保偏光纤的偏振特性测试和研究

当前，干涉型光纤传感器的发展，使得保偏光纤的需求显得相当迫切，随之而来拉制单模保偏光纤的技术愈来愈普遍且已相当成熟。在光纤陀螺研制过程中保偏光纤起着举足轻重的作用。它可使光纤陀螺中传输的偏振光状态保持稳定的模式，从而，可减少由偏振光不稳定性的干涉带来的陀螺漂移的影响。因此研究保偏光纤的偏振传输特性和其参数测量就显得相当重要。我们可以从光纤陀螺（ＦＯＧ）的输出特性表达看出光偏振因素的影响，Ｓａｇｎａ     

含金属纳米线多孔铝膜微偏振器的研究

含金属纳米线的多孔铝膜在近红外光区表现出较好的偏振特性。基于金属线栅偏振器的偏振原理,从金属纳米线对不同方向偏振光的消光机理出发,构建了以一排纳米线为研究对象的理论模型,分别计算了电矢量平行于纳米线轴向的偏振光（P）和电矢量垂直于纳米线轴向的偏振光（S）垂直入射时的光学损耗。在入射光波长固定的条件下,得到了P分量光、S分量光的透射率与模板孔径的关系。     

基于EMD-TFPF的仿生偏振光罗盘去噪方法

为了提高仿生偏振光罗盘定向精度,降低罗盘在进行航向角测量时存在的高斯白噪声,基于经验模态分解(EMD)和时频峰值滤波(TFPF),设计了一种用于仿生偏振光罗盘的EMD-TFPF联合去噪方法.在去噪过程中,首先将含噪声的航向角信号分解为不同的模态,对不同模态采用不同窗长进行时频峰值滤波,进而改善了单一窗长去噪对有用信号造成的衰减,有效提高了去噪算法的自适应能力.经过机载实验验证,采用该方法去噪后的仿生偏振光罗盘可以实现定向精度0.3259°,比原始信号精度提升了18.4％.     

保偏光纤耦合器制作研究

保偏光纤耦合器是应用保偏光纤制作的光耦合器，它是实现线偏振光耦合、分光以及复用的关键器件，是构成高精度光纤陀螺和光纤水听器的基础元件之一。本文主要介绍了保偏光纤以及保偏光纤耦合器的概况、制作方法和工艺技术。     

一种基于改进太阳子午线拟合方法的仿生偏振光定向系统

为设计一种自主性强、精度高、抗电磁干扰能力强的定向系统,以昆虫获取大气偏振模式的感知机理为基础,设计了一种新型的成像式仿生偏振光定向系统.该系统使用具有微偏振阵列结构的CMOS相机作为主要的偏振信息采集设备,使用DSP/ARM架构的NVIDIA JETSON TX2嵌入式处理器进行信息解算,具有体积小、运算能力强等优点.通过研究大气偏振模式中偏振度和偏振角图像的对称性,针对已有航向角解算方法在太阳子午线提取精度方面的不足,设计了一种对称轴粗提取之后通过连续旋转法精确提取太阳子午线的算法,最终实现定向精度0.3335°,在最小二乘对称轴粗提取法的基础上定向精度提升了19.05％.     

The polarization of celestial X-rays

The processes by which X-radiation may be emitted by celestial sources are investigated, and the net polarization such radiation would possess is predicted. The amount of polarization observed at the Earth would depend both on the mechanism producing the radiation and on the fractional extent of the source over which it is coherently polarized. Highly polarized X-radiation would suggest synchrotron emission as the source mechanism. Radiation whose polarization is low but nonzero would be produced by synchrotron emission from a source whose magnetic fields are inhomogeneous on a large scale, or by bremsstrahlung of electrons whose velocity vectors lie in one predominant direction. Nonobservable polarization would result from sources of synchrotron radiation whose magnetic fields show small-scale irregularities, from the bremsstrahlung of electrons whose velocity vectors are either random or spherically symmetric in direction over the entire source, or from sources whose mechanism of producing the radiation imparts no net polarization, e.g., thermal radiation from neutron stars, line radiation from electronic shell transitions within atoms, and the inverse Compton effect. Measurement of the net polarization of the X-rays from the several known celestial sources could thus lead to the specification of the mechanisms capable of producing the radiation from such sources.     

粗糙表面偏振二向反射特性建模方法研究

针对地面目标光学偏振特性预测对基础材质粗糙表面偏振二向反射特性建模的需求,对比分析国内外常用的经验、物理和半经验等3种偏振二向反射分布模型的优缺点及其适用范围,得出半经验模型更适用于地面目标光学偏振特性预测.在此基础上,研究基于半经验Priest-Gemer模型的参数反演方法,并提出相应的测试方法,设计试验测试验证平台.最后,对模型中的影响因子进行仿真分析,分析结果表明：目标表面偏振二向反射特性与表面纹理特征、复折射率、入射光角度、探测方位角、天顶角等因素相关,且复折射率对目标表面反射率及反射光的偏振度影响较大,粗糙度会影响遮蔽与阻挡效应,使其产生突变效应.     

A multiscale transform denoising method of the bionic polarized light compass for improving the unmanned aerial vehicle navigation accuracy

In recent years, the bionic polarized light compass has been widely studied for the unmanned aerial vehicle navigation. However, it is found from the obtained investigation results that a polarized light compass with a sensitive and high dynamic range polarimeter still provides inferior output precision of the heading angle due to the presence of the noise generating from the compass.The noise is existed not only in the angle of the polarization image acquired by polarimeters but also in the out...     

Polarization Loss of a Satellite: Data Collection Sensor Link

Economy of data collection systems consisting of several widely dispersed sensor platforms monitored by satellite can be realized by using an inexpensive linearly polarized antenna on each platform. The polarization loss of such an antenna is calculated.     

Bioinspired polarized light compass in moonlit sky for heading determination based on probability density estimation

Bioinspired polarized skylight navigation, which can be used in unfamiliar territories, is an important alternative autonomous navigation technique in the absence of Global Navigation Satellite System(GNSS). However, the polarization pattern in night environment with noise effects and model uncertainties is a less explored area. Although several decades have passed since the first publication about the polarization of the moonlit night sky, the usefulness of nocturnal polarization navigation is ...     

Radar target identification of aircraft using polarization-diversefeatures

The characteristics and target identification potential of a representation of the information from two polarization-diverse measurements of the radar backscatter of an unknown target are considered. The locus of these two polarization-diverse waveforms, termed the transient polarization response (TPR), has been shown to be closely related to the geometry of the scattering centers of the target. The polarization-related components of features derived from the TPR concur well with the shape and orientation of the major scattering centers distributed in the downrange profile of the object. This illustrates the intuitively appealing result that the polarization of the backscatter, as represented by the TPR and mapped onto the modified polarization chart, is determined by target geometry. It is shown that both polarization-related and amplitude-related features derived from the TPR are useful for target identification. By using distance measures that depend on various components, the elliptical parametrization information alone is sufficient to allow satisfactory target identification at SNRs of 0 dB and above. The significance of this result is that the absolute amplitudes of the received horizontally polarized and vertically polarized channels need not be known. However, if amplitude information is known, target identification percentages improve     

极化滤波反射面隐身天线研究

介绍了一种极化滤波反射面天线,将天线工程中的周期结构反射面技术应用于解决飞行器天线的RCS问题,采用由金属丝栅网构成的周期结构作为天线主反射面,使其对正交极化的来波具有良好的透射性,从而降低了天线的RCS。给出了此天线辐射方向图和雷达散射截面(RCS)的实测结果,并与普通金属反射面天线的结果进行了比较。     

High resolution exponential modeling of fully polarized radarreturns

A method for modeling full polarization radar target is considered. The approach taken is to estimate a set of target features which describes the target as a set of attributed scattering centers. Each scattering center is characterized by its range, amplitude, and a polarization ellipse. An exponential model for the fully polarized radar return is described, and an algorithm for estimating the parameters in this model is developed. The modeling procedure is applied to compact range measurements of model aircraft