NM7000B航向设备DC-LOOP告警故障

本文通过对仪表着陆设备的原理和故障进行分析,并对设备的具体故障进行维护研究。目前在华北地区仪表着陆系统主流设备为NORMARC7000B。由于设备是24小时不间断发射信号,若出现设备告警情况,会直接影响到飞机在进近或着陆过程中获取的ILS信号,从而影响飞机的飞行安全。因此做好设备的维护工作是保障空管设备平稳运行的重要基础。     

仪表着陆系统下滑台故障及解决

仪表着陆系统通过地面信标台发射出的无线电信号,在距机场入口25NM、左右±10°、与地面夹角8°的空域范围内形成一个虚拟近场通道,为进近着陆的航空器提供精密的航向道信号与下滑道信号,使得飞机在飞行降落的过程中能够按照无线电信号的指引,准确、平稳的降落在跑道上,属于精密进近着陆的引导体系.     

仪表着陆系统飞行校验周期延长研究

仪表着陆系统是飞机进近着陆的关键设备，其信号质量直接影响民航安全运行水平， 为确保其持续正常，按照民航规章，每 6 个月要对其进行一次定期飞行校验，随着设备数量的持续增加，给校验运力和航班支持率带来了极大困难。另一方面，设备运行单位外场信号测试手段不断丰富，有效地补充了对仪表着陆系统空间导航信号的日常监测。因此中国民航可进行试点尝试，根据设备运行状况合理设置校验周期，成熟后开始推广应用。     

M型下滑天线监测控制单元(MCU)原理及故障检修

仪表着陆系统是国际民航组织批准使用的精密进近系统，由航向设备、下滑设备及指点标或测距仪设备组成，其中下滑设备天线类型可根据场地情况选择零基准型、边带基准型和 M 型天线。本文在此分析了 NM7000B 型仪表着陆系统 M 型下滑天线 MCU 工作原理，介绍重庆江北国际机场 20L 下滑台 MCU 故障分析处置过程，为其他机场类似设备故障维修提供借鉴。     

民航仪表着陆系统超期运行风险评估及控制策略研究

仪表着陆系统(ILS)即盲降,是应用最为广泛的飞机精密进近和着陆引导系统.它的作用是由地面设备发射的两束无线电信号实现航向道和下滑道指引,建立一条由跑道指向空中的虚拟路径,使飞机沿该路径安全平稳降落,最终实现安全着陆.通常由一个航向信标台、一个下滑信标台和几个指点标组成.     

“导航原理与系统”虚拟仿真实验平台设计

为了加强导航原理与系统课程建设,让学生更直观的形成航空器天、地、空三维一体的导航整体概念,基于NM7000仪表着陆系统,结合设备巡检规程和维修操作流程,开发设计虚拟仿真实验平台。该平台能够实现对仪表着陆导航设备深入了解,快速掌握信号测试和故障的排除方法,不仅对于民航类专业院校有一定实用价值,对提升民航设备运行保障部门业务培训也有很大帮助。     

GBAS飞行测试仿真验证

地基增强系统(GBAS)能够弥补传统导航系统的诸多缺陷。为了评估 GBAS 系统的导航性能和系统性能,验证 GBAS 进近服务在不同运行条件下的总体性能,通常需要展开相应的飞行测试。考虑到 GBAS 飞行测试需要结合特定的测试设备和运行环境来进行,过程一般十分复杂。在实验室环境下,结合 Flight Gear 和 Matlab 软件,采用仿真数据代替实测数据,仿真验证 GBAS 系统的 I 类精密进近(CAT I)与着陆阶段所需导航性能(RNP)。仿真结果表明,GBAS 系统可以满足 CAT I 进近和着陆的性能要求,能够为基于北斗的 GBAS 技术在民航领域中的推广提供解决方案。     

地基增强系统(GBAS)飞行试验分析

作为一种新型的、基于卫星导航系统的精密进近和着陆系统,地基增强系统(Ground Based Augmentation System,GBAS)与其他传统的地基无线电精密进近和着陆系统在系统构成和应用上有很大的不同,因此,GBAS系统飞行校验的方法和校验内容也和这些传统的系统不一样。本文分析了在国内多个机场进行GBAS飞行试验的数据结果并据此对GBAS地面子系统的性能进行评估。结果显示GBAS系统可以满足CATI进近和着陆导航系统的精度要求,VDB信号覆盖和数据连续性也可以满足试验要求。     

一种着陆导航系统电磁环境的评估方法

着陆导航系统是飞机安全飞行的一个重要保障,机场电磁环境的恶化严重影响到飞机着陆引导安全。以仪表着陆系统为例,分析着陆引导的基本原理,给出了着陆引导过程中飞机接收信号的数学模型,并基于此模型提出了一种机场电磁环境的评估方法,最后利用计算机仿真验证了该方法的有效性。     

地基增强系统(GBAS)飞行验证方法研究

为改善终端区导航服务性能,支持 GPS 差分精密进近和着陆,国际民航组织提出了地基增强系统(GBAS)。为验证地基增强系统是否满足民用航空运行标准,需要对其进行飞行验证。本文详细讨论了对 GBAS 系统的飞行验证过程,包括地面子系统和机载子系统的平台建设, 以及飞行验证方法。试验结果表明被测 GBAS 系统符合国际民航组织颁布的 GBAS 运行标准,满足一类精密进近要求。     

自适应光学系统运行失稳检测方法

自适应光学（AO）系统校正像差是提高光学系统性能的有效技术手段。为了保证AO系统长时间安全、稳定地工作,需要对AO系统运行的数据进行监测,识别系统失稳状态以提供决策建议。基于以上目的,建立了一套127单元AO系统失稳数据仿真平台,通过该平台仿真得到了4种闭环失稳异常。基于变形镜控制电压RMS指标使用Kmeans聚类、K-NN分类和ARIMA预测3种机器学习方法进行识别检测。3种方法在不同类型异常数据中的检测结果有所不同,说明3种异常检测方法对系统失稳检测均有一定的效果和适用范围,在实际使用时,可以根据需要选择一种或综合多种方法进行检测。     

Medical and safety monitoring system over an in-cabin optical wireless network

An integrated health and safety monitoring system for aircraft environments using commercially available medical sensor modules and custom made safety sensors in conjunction with an appropriate database supervised through a human–machine interface is implemented. The application described aims at preventing critical health- or safety-related situations during the flight. The health monitoring part of the system is capable of collecting all relevant data, essential in analysing a passenger's health profile. These data, comprising of body temperature, blood pressure, pulse oximetry and electrocardiogram, are throughput and transmitted over a wireless optical intra-cabin link to a server. Furthermore, and in order to reduce the cabin crew workload, along with the health data from a specific passenger group, seat-embedded safety sensors provide information for all passengers' flight safety parameters (such as table upright, seat-belt closed, etc.). The data gathered by the system in a central server can, in its entirety, be stored, processed or acted upon in real time.     

An IDDQ sensor for concurrent timing error detection

Error control is a major concern in many computer systems, particularly those deployed in critical applications. Experience shows that most malfunctions during system operation are caused by transient faults, which often manifest themselves as abnormal signal delays that may result in violations of circuit element timing constraints. We present a novel complementary metal-oxide-semiconductor-based concurrent error-detection circuit that allows a flip-flop (or other timing-sensitive circuit element) to sense and signal when its data has been potentially corrupted by a setup or hold timing violation. Our circuit employs on-chip quiescent supply current evaluation to determine when the input changes in relation to a clock edge. Current through the detection circuit should be negligible while the input is stable. If the input changes too close to the clock time, the resulting switching transient current in the detection circuit exceeds a reference threshold at the time of the clock transition, and an error is flagged. We have designed, fabricated, and evaluated a test chip that shows that such an approach can be used to detect setup and hold time violations effectively in clocked circuit elements     

Soyuz mishap sounds alarms

An unsettling event during a Soyuz spacecraft's descent from the International Space Station (ISS) on 3 May was an unwelcome reminder of the outpost's complete dependence on the Russian vehicle for trips back and forth to Earth-until the US shuttle fleet is back in action. It also was a reminder that reliable software can be almost as critical as reliable hardware in space, especially when working with unfamiliar equipment. So when contact with the capsule was lost about 15 minutes before landing. For two hours there was no word on the fate of the crew. The problem was a software glitch in the new control computer that had apparently confused the spacecraft's navigation system. Instead of enduring a maximum G-force of 4 to 5 for about a minute as the vehicle decelerated during the planned shallow glide approach to the landing point, the crew suddenly faced twice that amount as the capsule plunged steeply into the atmosphere before reaching the ground 450 km short of where rescue teams were waiting.     

Soft computing applications in aircraft sensor management and flight control law reconfiguration

A sensor management system based on soft computing techniques has been developed and implemented in the flight control system of a small commercial aircraft. Unlike in the conventional sensor management system, the signals from sensors are assigned weights based on fuzzy membership functions and the consolidated signal is computed as a weighted average. This approach improves the quality of the consolidated signal and reduces transients due to sensor failures. This soft voting is extended to soft flight control law reconfiguration. In addition, a virtual sensor has been introduced as an arbitrator which enables the isolation of the failed sensor in the duplex operation and the detection of a sensor failure in the simplex operation. The effectiveness of the proposed methods is demonstrated by using an extensive simulation model of a small commercial aircraft, developed by airframe and control system manufacturers on the basis of an existing business jet. Furthermore, the system has been successfully evaluated and compared to standard techniques by means of pilot-in-the-loop simulations on the Research Flight Simulator of the National Aerospace Laboratory in The Netherlands. This application, developed within a Brite/EuRam research project, is characterized by the effective combination of novel soft computing techniques with standard, well proven methods of the aircraft industry. The properties of the conventional sensor management system have been retained, with the additional advantage that the quality of the consolidated signal is improved, the failure-induced transients are reduced, and the consolidated signal remains available up to the last valid sensor.     

基于多通道LFMCW雷达的低空风切变风速估计方法

在飞机起飞和进近着陆阶段中,风切变是一种对飞行危害最大的气象现象,如何有效地探测风切变并及时地规避危险对保障飞行安全至关重要。本文提出了一种将多通道线性调频连续波(Linear Frequency Modulated Continuous Wave, LFMCW)雷达应用于低空风切变检测中的实现方法。首先介绍了多通道LFMCW雷达的信号模型,然后利用空时自适应处理(Space-Time Adaptive Processing, STAP)方法抑制地杂波并匹配风切变信号,最后通过双脉冲重复频率(Dual-Pulse Repetition Frequency, D-PRF)解速度模糊法订正模糊速度,从而实现了风速的精确估计。后续实验仿真结果证明了本文所提方法的有效性。      

仿生小波变换在飞机发动机故障诊断中的应用

飞机发动机是一种复杂的旋转机械,故障种类多而且难以辨别。为了保证飞行安全,对飞机发动机的故障进行正确、快速地检测,文中应用仿生小波变换对某型涡轮风扇发动机在飞行中空中停车的振动信号作了分析。实验结果表明,对在频谱图上难以找到其相应的明显频率成分的准周期故障信号,利用仿生小波变换(BWT)的自适应调节功能,使得故障信号的细节成分更加地突出,对比该频率和故障情况下计算出的特征频率,可以找出故障的原因。     

Local area augmentation of GPS for the precision approach ofaircraft

The Federal Aviation Administration (FAA) is investigating the feasibility of using the Global Positioning System (GPS), together with local augmentation as the primary navigation system for the Category II and III precision approach of aircraft. This augmented system would be known as a local area augmentation system (LAAS) because it would place subsystems on the ground at or near an airport to greatly enhance the performance of airborne GPS receivers approaching that airport. The LAAS would complement space-based augmentations of GPS, such as the wide area augmentation system. When complete, the integrated system will meet stringent requirements on accuracy, integrity, continuity, and availability. Indeed, the LAAS will improve the airborne accuracy from approximately 100 m for stand-alone GPS to better than 1 m. This high accuracy is required so that LAAS can guarantee the integrity and continuity of the aircraft guidance during the approach phase of flight. Integrity requires the LAAS to detect any situations which threaten the safety of the landing, and notify the aircraft within 2 s of such a threat. Continuity is a competing consideration-it requires that the total number of alarms, true plus false, sent to the aircraft is very small. High continuity guarantees that the total number of aborted approaches is manageably small. Finally, availability is the fraction of the time during which LAAS is operational-providing position fixes with the specified accuracy, integrity and continuity. This paper describes the LAAS which has been proposed by the FAA. It discusses the fundamental operation of the LAAS     

TAWS低空风切变告警功能仿真验证平台设计

低空风切变对飞机运行安全会产生严重的威胁,而地形感知与告警系统(TAWS)的Mode 7能够根据飞机当前空速、攻角、无线电高度等探测低空风切变的存在,从而提示飞行员躲避危险,避免可控飞行撞地(CFIT)的发生以确保飞行安全。为了解决TAWS Mode 7功能验证时难以建立真实装机试飞环境的问题,针对某航空研究所研制的TAWS工程样机,设计了低空风切变探测功能的仿真验证平台。仿真验证平台以低空风切变模型和六自由度飞机模型为核心生成低空风切变探测所需的数据,利用飞行场景数据库进行多次仿真,可以验证TAWS Mode 7是否能在飞机穿越风切变时给出准确的提示和告警信息。