气压高度表辅助下GPS接收机自备完善性监测可用性研究

 对我国范围内飞机非精密进场及终端航行时全球定位导航系统（ＧＰＳ）接收机自备完善性监测（ＲＡＩＭ）的可用性进行了研究，分析了气压高度表辅助和故障偏置大小对ＧＰＳＲＡＩＭ可用性的影响。结果表明：气压高度表与ＧＰＳ组合是提高ＲＡＩＭ可用性的有效措施；过大或过小的偏置误差将产生较小的漏警概率，而中等大小的故障偏置则产生较大的漏警概率     

Leveraged fault identification method for receiver autonomous integrity monitoring

Receiver autonomous integrity monitoring(RAIM) provides integrity monitoring of global positioning system(GPS) for safety-of-life applications.In the process of RAIM, fault identification(FI) enables navigation to continue in the presence of fault measurement.Affected by satellite geometry, the leverage of each measurement in position solution may differ greatly.However, the conventional RAIM FI methods are generally based on maximum likelihood of ranging error for different measurements, thereby causing a major decrease in the probability of correct identification for the fault measurement with high leverage.In this paper, the impact of leverage on the fault identification is analyzed.The leveraged RAIM fault identification(L-RAIM FI) method is proposed with consideration of the difference in leverage for each satellite in view.Furthermore,the theoretical probability of correct identification is derived to evaluate the performance of L-RAIM FI method.The experiments in various typical scenarios demonstrate the effectiveness of L-RAIM FI method over conventional FI methods in the probability of correct identification for the fault with high leverage.     

卫星导航接收机自主完好性监测算法研究

针对航空导航定位高可靠性的要求和GPS接收机观测噪声分布的特点,研究将粒子滤波算法应用于接收机自主完好性监测（RUM）中.通过粒子滤波算法对状态进行精确估计,利用对数似然比建立一致性检验统计量进行故障检测与隔离.对算法进行了数学建模,描述了完整的RAIM算法详细流程.通过实测数据对提出的RAIM算法进行验证,结果表明：粒子滤波算法在非高斯测量噪声情况下可以对GPS接收机状态进行精确的估计,利用对数似然比建立的一致性检验统计量能有效地检测并隔离故障卫星,验证了该算法应用于GPS接收机自主完好性监测的可行性和有效性.     

基于奇异值分解的接收机自主完好性监测算法

基于最小二乘法残差的接收机自主完好性监测（receiver autonomous integrity monitoring，RAIM）算法本质是一种基于伪距残差矢量的一致性监测算法，但由于残差矢量中各分量具有一定的关联性，掩饰了某些重要的不一致性信息。为了消除这种关联性，提出了一种基于奇异值分解的接收机自主完好性监测方法。在方法中利用奇异值分解对伪距观测矩阵中的观测系数矩阵进行分解，获得奇异值空间矢量和奇异值空间矩阵。基于奇异值空间矢量构造能够直接反映故障卫星偏差信息的检验统计量，从而可以简便地进行粗差监测，更好地满足完好性监测需求。鉴于实际中完好性故障包含运控系统故障、导航系统故障、信号传播异常以及地面接收处理故障等多类因素，以脉冲型和阶跃型两种故障方式进行基于奇异值分解的RAIM故障检测与识别，并开展仿真分析研究。结果表明，提出的方法能够正确检测、识别故障卫星，在特定参数下能够达到很好的故障识别率，即当误警概率设置为1×10-5/h、引入阶跃故障误差为25 m时，算法能够实现98.8%的故障识别率。     

基于Kalman滤波和奇偶矢量法的优化RAIM算法

针对传统RAIM算法很难检测微小伪距偏差的问题,可以通过对多个历元的统计检验量进行归一化处理,增大统计检验量的非中心化参数,提高对微小故障的检测率.Kalman新息检测法可以对卫星的故障进行独立检测,具有运算量小、在少星情况时仍能进行故障检测和识别的优点,但是对微小伪距偏差不敏感.针对两种方法的优点提出了基于Kalman滤波和奇偶矢量法的综合RAIM算法.仿真结果表明,该方法不仅可以提高对微小伪距偏差的检测率,同时减少了对可见卫星数的要求,验证了该算法应用于接收机自主完好性检测的可行性和正确性.     

双卫星故障条件下的RAIM可用性研究

现有的关于接收机自主完好性监测（RAIM）算法大部分是基于单颗卫星故障的假设,但随着GPS技术的发展,多颗卫星发生故障的可能性已不能再被忽视,特别是两颗卫星同时发生故障的情况。本研究基于对水平定位误差保护级（HPL）的分析,从一颗卫星故障的可用性出发,推导出两颗卫星故障时的可用性。率先给出了在两颗卫星故障的情况下,天津区域内RAIM算法的可用性。仿真结果表明：两颗卫星故障的可用性低于单颗卫星故障的可用性。     

Galileo系统完好性处理的方法研究

对于卫星导航系统而言,系统所能提供的完好性指标和导航定位精度是同样重要的。欧洲的Galileo系统将在2008年建成,届时它将与美国的GPS系统相互补充。本文在对GMileo系统导航定位指标分析的基础上,结合系统完好性监测的设计特点,推导了系统地面完好性信道(GIC)监测算法和用户自主完好性(RAIM)监测算法,建立了数据完好性播发体制。     

GNSS用户端自主完好性监测研究综述

随着全球卫星导航系统的快速发展,对航空安全提出了挑战,完好性监测问题愈发凸显,用户端自主完好性监测(RAIM)是研究的重点之一。针对RAIM问题,首先介绍了所需导航性能的4个重要参数:精度、完好性、可用性和连续性。从单卫星故障下的RAIM、多卫星故障下的RAIM、高斯噪声下的RAIM 3个方面,综述了国内外相关的重要研究,主要涉及了3个层次内容:算法、计算保护限值和可用性,并指出了目前研究存在的不足。其次介绍了近期研究的新趋势与取得的成果。最后,展望了未来的研究方向。     

卫星导航系统中的RAIM技术

】全球定位系统（ＧＰＳ）已经达到初始运行能力，其完好性还不能满足全部飞行阶段的要求。接收机自主完好性监控（ＲＡＩＭ）为ＧＰＳ的航空用户提供了完好性监控手段。文中集中讨论了实现ＲＡＩＭ的几种检测和判定方法，并对ＲＡＩＭ技术及其潜能进行评估     

卫星自主完好性监视算法研究

民用航空对导航系统的完好性具有严格的要求。随着卫星导航系统在飞机上的广泛应用,GPS接收机自主完好性监视越来越受重视。针对GPS接收机自主完好性监视算法进行了研究。在对RAIM 判定原则及流程、基于最小二乘的故障检测算法和完好性要求下的可用性判断研究的基础上,通过仿真对所研究的算法进行相关的分析,结果表明,作为目前一种仅依靠接收机自身获取定位观测量进行监控的方法,RAIM算法在一定程度上增强了定位结果的可信性,满足了自主完好性监视的要求。     

User-level reliability monitoring in urban personal satellite-navigation

Monitoring the reliability of the obtained user position is of great importance, especially when using the global positioning system (GPS) as a standalone system. In the work presented here, we discuss reliability testing, reliability enhancement, and quality control for global navigation satellite system (GNSS) positioning. Reliability testing usually relies on statistical tests for receiver autonomous integrity monitoring (RAIM) and fault detection and exclusion (FDE). It is here extended by including an assessment of the redundancy and the geometry of the obtained user position solution. The reliability enhancement discussed here includes rejection of possible outliers, and the use of a robust estimator, namely a modified Danish method. We draw special attention to navigation applications in degraded signal-environments such as indoors where typically multiple errors occur simultaneously. The results of applying the discussed methods to high-sensitivity GPS data from an indoor experiment demonstrate that weighted estimation, FDE, and quality control yield a significant improvement in reliability and accuracy. The accuracy actually obtained was by 40% better than with equal weights and no FDE; the rms value of horizontal errors was reduced from 15 m to 9 m, and the maximum horizontal errors were largely reduced.     

Sole means navigation in US Navy aircraft

The current edition of the US Federal Radionavigation Plan, issued in 1984, presents a consolidated federal plane on the management of those radionavigation systems which are used by both the civilian and military sectors. It states the US Dept. of Defense (DoD) goal to phase out the use of TACAN, VOR/DME, OMEGA, LORAN C, and TRANSIT in military platforms and for Global Positioning System (GPS) to become the standard radionavigation system for DoD. This would eliminate all the current sole-means air navigation systems (TACAN and VOR/DME) aboard military aircraft. Instrument Flight Rule (IFR) operations within controlled airspace requires an operating sole-means air navigation system to be aboard the aircraft. The authors investigate the requirements for GPS certification as a sole means air navigation system in the US National Airspace System (NAS); discuss the implication for GPS user equipment (UE) hardware and software; describe the actual UE implementation; and discuss approaches for UE integration with flight instruments on US Navy aircraft     

用于卫星导航多星故障识别的新方法

 通过分析广义似然比方法,指出该方法不能用于多星故障识别。为能够快速识别多颗故障卫星,提高卫星导航定位系统的可靠性,提出了一种可以用于多颗故障卫星识别的接收机自主完整性监测（RAIM）的新方法——假设验证法。该方法对所有可能的故障卫星组合进行假设验证,对每种假设的故障卫星组合计算出卫星伪距偏差,然后利用此偏差构造一个新的奇偶残差矢量,最后利用特定的故障识别准则进行判断。以识别2颗故障卫星和识别3颗故障卫星为例进行了计算机仿真,结果显示：假设验证法故障正确识别率高于85%,高于现有的可用于多星故障识别的最优奇偶矢量法,可以有效提高卫星导航系统的可靠性。同时,与最优奇偶矢量法相比,假设验证法不需要求取矩阵广义特征向量,计算量将减少90%以上。     

基于气压高度辅助的机载自主完好性监测算法

卫星接收机自主完好性监测是指根据用户接收机的多余观测值监测用户定位结果的完好性,其目的是在导航过程中检测出发生故障的卫星,并保障导航定位精度。针对卫星接收机自主完好性监测算法可用性不足的问题,结合机载实际导航系统配置,提出了一种基于气压高度表辅助的机载自主完好性监测算法。综合利用卫星导航系统及气压高度表观测信息,建立联合系统的观测模型,推导了基于多解分离的完好性监测及保护级别计算方法。仿真结果表明,相比于传统的接收机自主完好性监测算法,该算法在可见星为5颗时仍能识别故障卫星。该算法具有更好的故障检测能力及可用性,能有效提高卫星导航系统的完好性监测性能,从而保证卫星导航系统的精度和可靠性。     

时-集综合的接收机自主完好性监测方法研究

提出了将时域处理和集合统计综合实现接收机自主完好性监测的方法。对卡尔曼滤波的新息检测方法进行了数学建模,分析了其优点和缺陷,并将其与基于瞬时(Snapshot)集合冗余一致性检测的RAIM的方法进行综合,称之为时-集综合的接收机自主完好性监测(TimeandSetCombinedReceiverIntegrityAutonomousMonitoring,TSC-RAIM)。计算机仿真结果表明,该方法不仅可以减少对可见星数目的要求,弥补SnapshotRAIM对多故障不敏感的缺陷,同时提高了故障检测的概率。     

星载GPS测量数据预处理方法研究

针对低地球轨道(LEO)卫星星载全球定位系统(GPS)接收机应用的特点,对星载GPS测量数据误差及其对周跳探测的影响进行了分析,提出TurboEdit数据预处理方法中周跳探测算法的改进算法。在原周跳判断算法的基础上,通过引入与测量数据观测高度角相关的加权系数,将周跳探测与测量误差紧密联系起来。根据观测高度角的变化对测量数据误差进行估计,并根据估计情况对加权系数取值,从而实现对周跳探测算法进行调节,达到降低周跳探测失误率的目的。增加参与定轨计算的观测数据量,提高了低轨卫星连续定轨的能力。通过GRACE编队卫星实测数据对改进算法进行了仿真验证。     

基于惯性辅助的北斗接收机完好性监测方法研究

针对传统卫星导航接收机在卫星数小于5颗及卫星星座构型不佳的情况下无法实现卫星故障识别与隔离的问题,结合卫星导航接收机在弹上的实际应用情况,利用惯导的辅助数据设计了一种基于多级Kalman滤波的北斗接收机完好性监测方案,给出了卫星导航接收机的RAIM滤波器结构与故障检测和隔离方法,并对其可用性进行了推导。该方案经过仿真分析及实验测试,结果表明在4颗可见星的条件下,可有效检测并隔离单星阶跃、慢速漂移、慢速随机等北斗卫星伪距和伪距率故障,从而使北斗接收机能够提供连续、精确的导航定位功能。     

Flight Test Evaluation of a New GPS Attitude Determination Algorithm

A new Global Positioning System (GPS) Attitude Determination Algorithm (GADA) is proposed, featuring the capability to keep its accuracy, even when the line-of-sight angle (LOS) of a given satellite vehicle (SV) is below the GPS horizontal antenna plane (HAP). The GADA model has been developed and evaluated through simulations and flight test campaigns, which comprised static and dynamic flight profiles, to best characterize the algorithm performance. As attitude reference a complete flight tests instrumentation (FTI) system was integrated into the testbed for the flight test campaign. The attitude measurements given by GADA and REQUEST algorithms are compared with those given by FTI (i.e., reference system). The results show that GADA accuracy is significantly better than that of REQUEST, for all flight conditions.     

带FDI算法的无人机组合导航姿态确定控制系统设计

无人机导航系统的作用是提供导航数据给飞控计算机作为制导和控制用,因为飞控计算机的性能在很大程度上依赖于导航数据,导航系统的某一个错误可能会导致整个无人机的失败,因此,导航系统应具有故障检测和隔离(FDI)算法,介绍了一种用于无人机导航的FDI和低成本的组合导航系统,硬件包括低成本商业用MEMSIMU、GPS接收器、磁力计和导航计算机,软件包括带FDI算法的卡尔曼滤波。     

Impact of one satellite outage on ARAIM depleted constellation configurations

Advanced Receiver Autonomous Integrity Monitoring(ARAIM) is a new technology that will provide worldwide coverage of vertical guidance in aviation navigation. The ARAIM performance and improvement under depleted constellations is a practical problem that needs to be faced and researched further. It is a shortcut that improves the availability in position domain whose key idea is to replace the conventional least squares process with a non-least-squares estimator to lower the integrity risk in exchange for a slight increase in nominal position error. The contributions given in this paper include two parts: First, the impacts of one satellite outage on different constellations are analyzed and compared. The conclusion is that GPS is more sensitive and vulnerable to one satellite outage. Second, a constellation weighted ARAIM(CW-ARAIM)position estimator is proposed. The position solution is replaced by a constellation weighted average solution to eliminate the constellation difference. The new solution will move close to the constellation solutions with respect to the accuracy requirement. The simulation results under baseline GPS and Galileo dual-constellation show that the one GPS satellite outage will knock the availability from 91% to only 50%. The performance remains stable with one Galileo satellite outage. With the assistance of the CW-ARAIM method, the availability can increase from 50% to more than80% under depleted GPS configurations. Even without any satellite outage, the proposed method can effectively improve the availability from 91.29% to 98.75%. The test results under optimistic constellations further verify that a balanced constellation is more important than more satellites on orbit and the superiority of CW-ARAIM method is still effective.