基于伪距信息的COMPASS-MEO导航卫星单星定轨分析

COMPASS-MEO导航卫星的伪距观测量包含星站距离、接收机钟差和卫星钟差以及各种噪声。本文首先分析了接收机钟差和卫星钟差在一定间隔内主要表现为线性变化的特性,可以考虑将接收机和卫星钟差作为测距的偏差和偏差变化率和轨道一起进行求解。其次,利用实测的MEO导航单星伪距数据,进行了数据预处理和定轨试验,分别对站间无时间同步信息和有时间同步信息两种情况进行定轨、残差分析和参数解算。使用重叠弧段、轨道预报和激光观测数据验证定轨结果的精度。结果表明,两种情况下的定轨结果无明显差别。该定轨方法可以运用于MEO导航单星精密轨道的计算。     

Efficient solution and performance analysis of 3-D positionestimation by trilateration

A new exact, explicit, and computationally efficient solution for three-dimensional (3-D) position estimation based on range measurements from three stations is proposed. The simple polynomial-type form of the new algorithm facilitates the performance analysis. Formulae are provided for both the variance and the bias of the position estimates. The systematic error is a joint effect of both the measurement noise and the system nonlinearity and its magnitude cannot be ignored if highly accurate localization is required. Performance evaluation results are presented for various conditions     

双向比对高精度物理时间同步方法

提出一种面向未来卫星在轨应用的闭环物理高精度时间同步方法。比较了所提方法与其他时间同步方法的区别与优势，建立了远程系统时间同步基本模型与误差传递模型，基于双向测距和时间传递技术分析了高精度钟差获取原理，给出了时钟调整环路的时域频域参数依赖关系。完成了高精度时间同步地面试验系统构建，测试了开环非调钟状态下钟差测量精度误差、闭环调钟状态下时间同步准确度误差以及长时运行情况下的时间同步监测结果。测试结果表明，该方法能够实现优于1 ns量级的时间同步，为高精度时间同步技术研究提供了新的途径。     

差分码偏差对PPP授时精度影响的研究

论文分析了不同机构差分码偏差(DCB)产品的天稳性.选取了2个外接氢原子钟的测站进行实验,以国际GNSS服务组织(IGS)发布的接收机钟差为参考值,分析了不同机构DCB产品对2个测站PPP授时精度的影响.实验结果表明:1)不同机构DCB产品的天稳性差异不大,中国科学院天稳性略优于德国宇航中心;2)2个测站使用不同机构的DCB产品估计钟差的均方差(RMS)和时间偏差(Bias)均优于0.4ns,其中中国科学院产品精度最高,RMS和Bias均优于0.2ns;德国宇航中心和欧洲定轨中心精度略差,但也能够达到亚纳秒级,可为下一步推广PPP授时应用提供一定的参考.     

基于不敏变换的动基座传感器偏差估计方法

提出了一种新的基于合作目标的动基座传感器误差绝对配准方法。该方法利用所获得的合作目标位置信息,将载体平台姿态角偏差转换为传感器测量偏差中的一部分,并建立偏差状态方程和测量方程。在此基础上,采用广义最小二乘方法以实现传感器测距误差的估计,不敏滤波的方法则用于实现平台载体的姿态偏差和角度测量偏差的实时估计。仿真结果表明,该方法实现简单,收敛速度快,可以实现单部动基座传感器的偏差估计。     

A Direct Solution to GPS-Type Navigation Equations

One solution to the navigation equations involves iteration on the 4 by 4 augmented range-direction-cosine matrix beginning with an assumed position and so assumed direction cosines, of which there are 12 for 4 satellites. An algebraic, direct solution to this same basic equation set has recently been published. Both of these methods are reviewed. We offer a direct solution using modified functions of the range magnitude data from four satellites to yield user's clock bias correction, user's position, and true range vectors if desired. The highest order of matrix inversion used is 2 by 2. The highest order, nonlinear equation is a numeric square root. The principle of the formulation is use of differences among the range magnitudes and range magnitudes squared. An additional auxiliary difference equation is formed. A computation basis uses the ephimeride differences and an orthogonal vector. The method offers convenience, speed, simplicity, low dimensionality, and precision, with no operational constraints.     

多无人机辅助定位信标的区域导航定位算法

针对卫星导航系统在受到干扰不可用的情况,研究了多无人机（UAV）辅助的区域导航定位算法。以无人机作为空基信号播发平台,向地面用户广播其位置信息及同步时钟信号,地面用户通过接收无人机位置及与无人机的距离计算出其实时位置。以地面战车为例,为解决伪距单点定位算法中的矩阵不可逆问题,消除地面用户接收机的钟差,基于列文伯格-马夸尔特（LM）算法,提出一种地面用户的定位解算模型,同时,为提高一般最小二乘算法的计算精度,提出了两步最小二乘定位算法。在分析2种算法静态定位精度的基础上,设计了基于车载惯性传感器和无人机辅助定位信息的组合导航实现算法,实现了对战车的连续定位。仿真结果表明,在GNSS拒止环境下,利用无人机播发的定位信标信号并结合地面用户战车自带的惯性导航系统,可以实现对地面用户的可靠连续定位,满足一定区域范围内用户的导航定位需求。     

GNSS广域差分改正数估计方法研究

随着我国北斗三号基本系统的正式运行,基于地面监测站的广域差分增强系统成为进一步提升卫星导航定位精度的手段之一。在码噪声多径误差修正(CNMC)的基础上,使用等效钟差方法实现GNSS卫星轨道与钟差误差的解耦,并依据卫星轨道运动的动力学特性,引入希尔差分方程描述卫星轨道误差变化,实现对轨道误差的实时卡尔曼滤波估计。基于GPS实测数据,对改正前后的用户等效测距误差(UERE)和定位精度进行了对比研究。实验结果表明,采用该方法,UERE标准差由改正前的0.456 m减小至0.227 m,降幅达到50.22%;整体水平定位误差(95%置信区间)由0.981 m减小至0.782 m,垂直定位误差(95%置信区间)由1.991 m减小至1.131 m,分别提升了20.29%和43.19%,差分改正效果明显。     

GPS选择可用性(SA)信号采集与建模

 分析了ＧＰＳ测量伪距的各组成部分,设计了一个ＧＰＳ数据实时采集系统,通过定位计算和时钟偏移滤波的方法分离ＳＡ误差信号,经检验指出ＳＡ误差信号基本是零均值的平稳随机过程,对一段时期定点观测到的ＳＡ误差信号进行ＡＲ（１３）的模型辨识,获得大量的模型数据,从时域和频域对模型参数进行分析得到一些有益的结论。     

Reducing geometric dilution of precision using ridge regression

A signal processing technique is proposed for improving position-fix navigation system accuracy performance when the geometry of the navigation landmarks (e.g. sensors) are nearly collinear. In the navigation literature, the accuracy degradation associated with a nearly collinear measure geometry is termed the geometric dilution of precision (GDOP). Its presence causes not only the variance of the position estimates to be highly inflated but also any bias terms which may be present in the model. Since a nearly collinear predictor matrix is mathematically equivalent to GDOP, it is proposed to use the ridge regression technique in a navigation signal processor. A position-fix algorithm based on ridge regression reduces the bias and variance inflation caused by GDOP and the overall mean-squared position error as well. Ridge regression contains the GDOP-sensitive least-mean-square (LMS) estimator as a special case. Even with a matched model, GDOP can inflate the mean-square error (MSE) of the ordinary least-squares estimator, whereas the ridge regression technique chooses a suitable biased estimator that will reduce the MSE, which is the main goal. The ridge concept is extended to include GDOP-amplified bias errors. A simple range/range navigation system is analyzed to illustrate the underlying principles of ridge regression     

正六面体工装误差对光纤惯组加速度计零偏标定精度影响分析

研究了利用大理石平板正六面体工装对光纤惯组进行标定时,工装误差对标定精度的影响。首先建立了标定模型,设计了12位置法的标定方案与解算方法,其次分析了工装误差对标定影响的量化关系,并提出减小误差的标定解算方法,最后对理论分析结果进行仿真验证。仿真结果表明,当长宽高为400mm的工装平面度、垂直度、平行度误差均为0.04时,加速度计零偏的标定误差达到0.0001g,与工装误差角大小量级相当。用12位置二向法解算零偏可减小该误差影响。     

一种改进的IMU加表标定模型及快速标定方法

针对MEMS产品工程应用的需求,提出了一种改进的IMU加表标定模型,更清晰地分离出与安装误差有关的投影关系阵以及与器件误差有关的刻度转化阵。并且,在此模型的基础上给出了不需转台的快速标定方法。投影关系阵不变,该方法减少了观测量,只需6位置来估计加速度计的零位和标度因数,同时进行了现场误差补偿。     

New Developments in Radar and Radio Sensors for Aircraft Navigation

Recent developments in airborne Doppler and ground mapping navigation radars and ground and satellite based radio systems are described. Simultaneous lobing and slope tracking techniques can remove the well-known Doppler sea bias error in fast and slowly moving vehicles. Doppler velocity information can be extracted from coherent forward-looking mapping radars, and high position fixing accuracy can be achieved by synthetic aperture radars. In radio navigation systems, such as Loran, Omega, and satellite systems, direct-ranging and differential techniques greatly reduce the geometric dilution and propagation effects which have plagued conventional radio navigation systems. The advantages gained by mixing of the data from these and other navigation sensors in a digital multisensor system are discussed and approaches for processing these data are suggested.     

Phase Monopulse Error Due to Nonuniform Noise Background

A phase monopulse antenna system can be used for the high accuracy tracking of active or passive objects in space or on earth. Far-field noise sources that are present in the background of the object being tracked will introduce an offset or bias error in the determination of the angle of incidence of the coherent sinusoidal wave received from the source. The dependency of this bias error upon the nonuniformity of the noise background or equivalently upon the asymmetry of the antenna patterns about the direction to the signal being tracked is determined. Although the variance in the measurement of the sinusoidal source direction can be reduced by increasing the post detection integration time, it is shown that the bias or offset error is unaffected by this change. In order to decrease the offset or bias error the predetection bandwidth must be reduced.     

基于惯性系的光纤寻北仪双位置寻北算法

由低精度光纤陀螺(Fiber Optical Gyroscope,FOG)组成的寻北仪具有结构简单、成本低的优点,但易受地磁和车上复杂外部环境的影响.针对低精度FOG存在地磁零位,寻北仪对外部晃动敏感的缺陷,通过对陀螺进行地磁零位补偿保证陀螺零偏稳定性,在此基础上提出了基于惯性系的双位置寻北算法.算法分别在两个对位进行惯性系寻北,利用双位置对消原理获得不受陀螺固定零偏影响的方位角并完成水平陀螺固定零偏的估计.实验结果表明,陀螺零偏稳定性0.15(°)/h,加速度计零偏稳定性150μg的惯性器件精度下,车上寻北误差1倍标准差小于4.5mil、极差小于10mil、对准时间小于5min.与传统双位置算法相比,所提算法在晃动基座条件下具有对准精度高,环境适应性强的优点.     

Inertial System Platform Rotation

Differential error equations are derived for the navigation errors of a local level undamped pure inertial platform that continuously rotates in azimuth. From these, the time response equations for the vector position error produced by a constant level gyro drift error, as a function of platform rotation rate, are computed and evaluated. It is shown that platform rotation attenuates the system position error due to level gyro bias and that this attenuation is a nonlinear function of rotation rate.     

Alpha-beta filters in polar coordinates with accelerationcorrections

The use of polar coordinates is sometimes computationally advantageous for tracking, but complications arise because the position of constant velocity targets is no longer a linear function of time as it is for cartesian coordinates. However, this difficulty can be avoided by using pseudoacceleration correction factors which are added to the prediction equations to give approximately correct system dynamics, but at the expense of an increase in system noise. For alpha-beta tracking filters, these correction factors can be included with minimal degradation in the steady-state error performance of the filter while simultaneously providing substantial reductions in bias errors     

舰载机理想着舰点垂直运动的预估与补偿

理想着舰点的垂直运动是影响着舰精度和安全的一个主要因素,因此必须加强舰载机对理想着舰点垂直运动的同步跟踪能力.为此,提出对理想着舰点垂直运动的位置和速度信号进行预估和补偿的方法,将垂直运动的位置和速度信号经过预估和补偿后分别引入到纵向自动着舰引导系统和飞控系统的垂向速度通道中,使得舰载机可以准确跟踪理想着舰点的垂直运动,以减小甲板运动对着舰的影响.针对不同海况条件,对设计的补偿器和预估器进行仿真验证,并与其他方法进行比较.结果表明本文提出的理想着舰点垂直运动预估与补偿方法可有效地补偿由甲板运动引起的着舰误差,显著提高了着舰的安全性和精确性.     

舰载捷联惯导系统的航行中快速在线标定

为实现舰载捷联惯导系统在航行中被快速标定的新需求，提出了一种捷联惯导系统在航行中快速在线标定的方法。首先，建立了简化的陀螺和加速度计输出误差方程，从而对Kalman滤波模型实现了降维。该模型以陀螺和加速度计零偏、标度因数误差等15个误差量为状态量，以速度误差和位置误差为量测量。设计了一种标定路径，该标定路径可由惯导系统中的双轴旋转机构实现。仿真结果表明，该方法能够在1800s内快速、准确地估计出15个误差量，具有工程实践价值。     

光纤陀螺仪中尖峰脉冲引起漂移 的误差分析及其抑制

首次分析了光纤陀螺仪探测器输出信号中频率固定的尖峰脉冲对光纤陀螺 仪零偏漂移的影响机理,给出了尖峰脉冲影响光纤陀螺仪零偏漂移的误差模型;根据干 涉式数字闭环光纤陀螺仪探测器输出信号的特点,提出了一种基于高速集成模拟开关的 时域选通尖峰脉冲抑制具体实现方法,实验验证了尖峰脉冲引起的零偏漂移大小和理论 分析接近,表明了误差模型的正确性,同时表明该方法能够有效降低尖峰脉冲引起的光 纤陀螺仪零偏漂移。