High accuracy navigation and landing system using GPS/IMU systemintegration

In this paper, the accuracy, integrity and continuity of function requirements for automatic landing systems using satellite navigation systems are discussed. Such a landing system is the integrated navigation and landing system (INLS) developed by Deutsche Aerospace (DASA/Ulm, Germany). The system concepts of the INLS are presented. It is shown how an INLS, based on system integration of a satellite navigation system (e.g., GPS) in realtime differential mode with an inertial measurement unit (IMU) in the accuracy class of an attitude and heading reference system (AHRS), can meet the requirements: the results given are mainly devoted to the accuracy issues. Using Kalman filter techniques, an in-flight calibration of the IMU is performed. The advantage of system integration, especially in dynamic flight conditions and during phases of flight with satellite masking, is explained. The accuracy, integrity and continuity of function of the INLS were proven by means of flight tests in a commuter aircraft using a laser tracker as a reference. These flight tests have shown that the short-term accuracy (<60 seconds) of the AHRS used within the INLS has been improved from low cost sensor quality to the accuracy of a high quality laser inertial navigation system (LNIS). With the presented INLS, a landing at any airfield, not equipped with conventional Instrument Landing System (ILS) or Microwave Landing System (MLS), is possible by using a very cost effective system. The INLS is a high accuracy navigation and landing system designed to be used instead of conventional landing systems at small airfields and to fill operational gaps of conventional navigation and landing systems in cruise and approach on large airports     

Microwave Landing System

The National Microwave Landing Systems (MLS) program is a joint DOT/DOD/NASA effort to implement a common civil/military precision landing system to replace the current Instrument Landing System (ILS). The MLS will be capable of providing precision landing guidance down to Category III minimum while allowing for complex approach paths in both the horizontal and vertical planes. The system is based on the Time Reference Scanning Beam (TRSB) technique which was selected by the International Civil Aviation Organization (ICAO) in April 1978 as the new international landing system standard. MLS is less susceptible to interference from the surrounding area and provides a greater signal coverage area than ILS.     

MLS: keeping pace with the future

It is argued that the instrument landing system (ILS) is now at its operational limit in terms of radio frequency availability, approach flexibility, and technology. The operational requirements for a microwave landing system (MLS), which will overcome key limitations of the ILS and provide growth to meet future requirements of precision landing systems, are discussed, John F. Kennedy (JFK) International Airport and LaGuardia Airport in New York City are discussed as examples to demonstrate the capabilities of MLS     

弹道导弹天文/惯性导航误差修正方法研究

通过分析导弹天文导航和惯性导航的导航原理和误差模型,在基于充分利用高精度天文导航参数的思想上,提出了组合导航的误差修正方法。首先对两种导航参数进行了归算,而后提出了利用多次的天文测量参数对惯性测量误差进行修正的方法。该方法能较为准确地分离出引起射程误差较大的关机点速度、位置等的误差值,从而为实现利用天文导航进行射程误差修正提供前提条件。仿真计算表明,该方法是行之有效的。     

Flight safety performance of the microwave landing system

The microwave landing system (MLS), which is scheduled to be implemented progressively over the next 10 years, is intended to supply the instrument landing system (ILS) as the international standard landing aid. MLS has been demonstrated to be superior to ILS from both performance and reliability standpoints, yet considerable debate persists on its relative merits. Although tolerance criteria for flight safety are embedded in these comparisons, flight safety has not been a major component of these discussions. The reasons why flight safety has not been an issue are addressed, and observations on the flight safety of MLS are related from a systems point of view. The effect of MLS on airport capacity is identified as a central issue. Observations are derived from a review of available documentation and operational results to date as well as discussions with the participants     

基于极限学习机的黑障区智能导航算法

在黑障区飞行阶段中,惯性导航系统会因缺少辅助导航系统而持续累积误差,导致飞行器导航系统可靠性下降。针对这一问题,提出了一种新的基于极限学习机的黑障区智能导航算法,通过极限学习机(ELM)对GPS正常工作的导航信息进行学习。在黑障区,利用学习得到的模型对惯性导航系统进行误差补偿,较好地修正了当GPS失锁时惯性导航系统的误差,避免了因误差累积而导致的导航信息发散。仿真结果表明,该算法能够保证在GPS失锁的黑障区中导航系统输出的信息有较好的可靠性和精度,能够为接下来的姿态调整和着陆准备提供良好的基础。     

MLS: a total system approach

A typical approach and landing operation is described. The microwave landing system (MLS) is then examined, its design characteristics and how it works are shown, and how the MLS design fulfils the user's operational requirements by protecting the guidance signal from reflected signal interference is highlighted. MLS angle system accuracy is discussed in great detail, and its reliability, integrity, and coverage volume are briefly considered. MLS availability at any runway to all aircraft types and their landing scenarios, which is accomplished using narrow scanning beam antennas, is examined     

Analysis of the Integrity of the Microwave Landing System (MLS) Data Eu nctions

The microwave landing system (MLS) transmits angle, data, andrange information for use by airborne receivers. In this paper, theintegrity of the data functions is analyzed in terms of the probabilityof undetected errors remaining in the data. The data format andintegrity requirements were derived from the MLS standards andguidance material defined by the International Civil Aviation Organization (ICAO). Results show that the performancerequirements can be met by: 1) averaging the received data bits ofseveral samples of the same word using a majority voting;2) reducing the bit error rate at the output of the receiver'sdecoder; and 3) a combination of the above techniques.     

侧向甲板运动补偿技术研究

 为提高着舰的安全性, 减小着舰误差, 研究了侧向甲板运动补偿机理, 设计了雷达测量轴跟踪滤波器, 导出了侧向甲板运动补偿指令模型, 建立了甲板运动补偿状态下侧向自动着舰导引系统结构配置, 仿真表明, 开发的甲板运动补偿技术可有效地补偿由海浪引起的着舰误差。     

The case for ILS

In response to the interest and activity in microwave landing systems (MLSs), the capability of instrument landing systems (ILSs) is examined and a case for their continued implementation is made. The changes that have been made with respect to electronic hardware, monitoring, and antenna systems in response to more stringent demands are reviewed. It is argued that there is no technical impediment to the installation of additional and upgraded ILS installations over the 1990s and that these installations would be cost effective and pay back the investments before being displaced by MLS     

民用飞机着陆系统安全性评估的故障树分析

飞机着陆系统是保障飞机安全进近着陆的关键系统,如何评估着陆系统满足安全性设计要求是系统设计的重要环节之一。阐述民用飞机安全性评估的基本流程,以微波着陆系统为例,针对给定的微波着陆系统框图,通过故障树分析方法,对完全丧失两侧微波着陆信息的失效状态进行定量评估,重点详述建树过程和建树方法。结果表明:故障树分析对系统架构的设计具有重要的指导作用,二者紧密结合、相互反馈;特别是当失效状态所对应的概率要求无法满足时,借助故障树分析产生的割集报告,能找出系统架构存在的薄弱之处和关键部位,从而采取有效的应对措施,完成对系统架构的优化设计。     

Autonomous navigation and guidance for landing on asteroids

This paper presents an autonomous landing navigation and guidance scheme for future asteroid sample return mission. An autonomous navigation scheme based on feature tracking technology is brought out firstly; secondly, desired descent landing trajectories with the initial and terminal constraints are planned in order to achieve arrive-at-time landing on an asteroid; then, two guidance control laws, based on error phase analysis method and PD plus PWPF method respectively, are designed to track reference descent trajectory; finally, the validity of the proposed scheme is confirmed by computer simulation.     

无人机下滑着陆DGPS/INS导航及引导系统的仿真与试验研究

介绍了一种采用输出校正方式DGPS/INS组合导航系统引导无人机下滑着陆的方案。给出了该方案的数学模型,对组合导航系统进行了数字仿真,并在数字仿真的基础上进行了动态跑车试验,验证了所设计的输出校正方式DGPS/INS组合导航系统能够满足引导无人机自动下滑着陆的精度要求。     

最小生理噪声进场航迹飞行管理方法

 微波着陆系统MLS的最优航迹计算以减小居民最敏感的生理噪声为基本优化性能准则,用感觉噪声级Sone为单位。计算了考虑了噪声传播时温度、风梯度、沿进场航迹附近区域生活居民区分布位置及密度等影响。通过对杜塞尔道夫-罗奥申航空港计算结果证实,使航空港附近居民的平均有效感觉生理噪声级(Sone)较原有Jeppesen标准方式降低了20％以上。     

GNSS双频导航信号用户完好性监测机制研究

用户完好性监测指标通常被用于衡量导航信息的可信度,针对单个卫星导航系统用户完好性监测指标过高、可用性较差的问题,提出一种全球导航卫星系统(GNSS)多系统双频信号联合完好性监测机制,该监测机制使用一定完好性风险分配值下的保护门限作为联合观测下的监测指标;另外,为了确保各种监测假设下的用户完好性,分别讨论了无故障及一颗卫星故障假设下的伪距观测误差获取、保护门限计算以及完好性风险指标分配等问题。仿真结果表明该用户监测机制可有效降低保护门限、提高可用性,在用于I类精密进近时全球大部分区域用户的可用性水平大于95%。     

FLOLS误差源建模与仿真研究

菲涅尔光学助降系统(FLOLS)是典型的舰载机光学着舰引导系统。分析了影响FLOLS着舰引导精度的指示误差源和光学误差源,包括稳定平台跟踪误差、光源位置与理想着舰点位置偏差、光源温度、飞行员视觉误差,研究了FLOLS相关系统的工作原理和着舰引导误差的产生机理,建立了各误差源的数学模型。通过对FLOLS着舰过程进行重复仿真,使用标准偏差统计方法,得到各着舰引导误差的统计特性,进而得出各误差源影响着舰精度程度比较。     

Exploiting GNSS signal structure to enhance observability

There are a number of different error sources, such as multipath and thermal noise, which corrupt satellite navigation waveforms from their theoretical structure. However, even under ideal conditions the broadcast signals have some degree of deformation as a result of the practical individual hardware implementation. For the most demanding users of satellite navigation, such as aircraft navigation and landing systems, it is important to characterize the nominal signal structure in order to detect minimal variations resulting from hardware-based errors. Thus far such precorrelation Global Navigation Satellite System (GNSS) signal quality monitoring has been performed through high gain antennas, which allow for raising the GNSS spectrum above the thermal noise floor and observing the structure of the signal directly at the front end output. This paper describes a new approach to achieve such observability based on signal processing techniques, such as dithering and averaging, which leverage the repetitive nature of the GNSS signal. The paper presents how these techniques can drastically improve the signal-to-noise ratio (SNR) in postprocessing, allowing for the direct analysis of GNSS signals using traditional front end designs and conventional antennas. Results are predicted using the appropriate theory and validated using data collected from the Global Positioning System (GPS).     

一种多径条件下的MLS接收机测角误差分析新方法

为了准确分析多径环境条件下微波着陆系统接收机测角误差,在深入分析微波着陆系统(MLS)测角原理的基础上,提出了一种基于扫描波束主瓣等效替代的误差分析方法。该方法通过把往返波束脉冲主瓣用高斯钟形替代,准确计算了接收的扫描脉冲-3dB门限前后沿误差,建立了多路径条件下统一实用的接收脉冲包络波峰位置偏移误差模型和锁住闸门测量误差模型。为验证模型准确性,以特定的多径环境条件为例,计算MLS接收机的测角误差,将计算结果与利用Mathias经典模型的计算结果进行对比,并通过计算机仿真进行验证。结果表明,采用主瓣替代方法能够较好地克服经典模型精确分析误差方面的使用不足和缺陷,且对多径条件下接收机测角精度的准确评定具有一定的实用价值。     

地形辅助制导系统

本文叙述一种地形辅助制导系统,用来修正惯性系统或其它导航系统的误差,以提高飞行器的制导精度。这种辅助系统含有一个卡尔曼滤波器,它将飞行器所飞过的实际地形信息与预存的地图进行比较和处理,从而估计出导航系统的误差。对于一般的丘陵地形,辅助制导后的精度可达到数十米的范围。它适用于飞机、巡航导弹、弹道导弹和其它武器运载系统,而且所需的设备简单,易于实现。     

基于差分卫星导航的着舰引导技术分析

着舰引导技术是航母/舰载机系统的核心技术,差分卫星导航相对定位精度高,广泛应用于近距离相对定位,基于差分卫星导航的着舰引导技术是当前着舰引导技术研究的热点.载波相位周跳是影响差分卫星导航相对定位精度的关键因素.本文在分析基于差分卫星导航的着舰引导系统架构的基础上,提出一种改进的包含周跳的卡尔曼滤波模型.该模型能够削弱差分卫星导航相对定位处理流程中载波相位周跳影响,提高相对定位精度,试验结果证明了本文所提卡尔曼滤波模型的有效性.