Autonomous Landing Guidance Systems

All weather tactical aircraft recovery and high sortie generation rates from forward, possibly battle damaged landing areas will reqire autonomous landing guidance systems which are independent of ground-based cooperative aids. A recently completed study has examined the operational requirements and assessed current and near term technology for an answer to this need. The Landing Systems Requirements/Synthesis Study has defined the Pilot/vehicle Interface and imaging sensor suite required, based on the concept of augmenting pilot forward vision with sensor imagery and guidance symbology on a HUD during low visibility landings. Image processing technology was also assessed for potential enhancement of the information presented to the pilot. This paper summarizes the final report of the Study, which is in publication.     

进场航班双目标调度的鲁棒优化研究

由于天气变化,导致进港飞机降落的处理时间不确定的情况经常发生.因此,需要在受到天气影响,进港飞机在跑道的处理时间不确定时提高跑道的利用率,减少飞机的延误成本.以最小化航班总延误成本和跑道总工作量为优化目标,建立降落飞机的处理时间的鲁棒优化模型,设计出Epsilon约束算法对能够快速得出进港飞机降落方案的Pareto前沿.通过实例证明了模型的可行性及有效性,对机场终端在天气变化时对进港航班的合理调度具有一定的指导作用.     

基于复近似消息传递的前视雷达成像分辨率增强算法

当机载/弹载雷达工作在前视状态时,由于成像场景内不同角度处目标的多普勒差异很小,很难得到 高的角度分辨率。针对海面舰船目标的前视成像应用,利用成像区域具有明显稀疏性的特点,提出一种基于复 近似消息传递压缩感知处理的前视成像角度分辨率增强算法,建立前视成像的线性观测信号模型,给出复近似 消息传递的迭代计算过程,以及多通道雷达前视成像的处理流程。通过仿真数据和 X 波段雷达实测数据的处 理结果验证了该方法的有效性。     

Synthetic vision for enhancing poor visibility flight operations

Visibility is important for the pilot controlling an aircraft in flight conditions close to the ground, particularly when landing. Therefore, poor visibility yields a great restriction for aircraft operations. Restrictions exist for landing sites which are equipped with facilities providing a landing approach aid like ILS since a minimum is required for visibility. For landing sites providing no approach aids, restrictions are much more severe. This holds even if aircraft are equipped with modern instrumentation and navigation devices. The natural view of the pilot is dependent on various meteorological conditions like darkness, dust, fog, rain etc. The degradation in view caused by these conditions can be compensated for partially or even completely by technical means providing artificial vision cues. Such technical means may be based on radar or optical sensor information. Concepts which employ these techniques are known as “Synthetic Visual Systems” or “Enhanced Visual Systems,” . The present paper is concerned with computer generated vision as a further technique providing visual cues for the pilot. Computer generated vision may be used in combination with the aforementioned sensor based techniques. Thus, it is possible to compensate for limitations which sensor based visual systems have in providing sufficient visibility range or in generating a normal looking image. In addition, computer generated imagery has the potential providing additional information to the pilot for controlling the flight path or for warning purposes. This potential can yield improved and/or more information as compared with the natural view when looking out of the cockpit window     

一种检测机场跑道辅助飞机着陆的系统设计

跑道作为机场的关键设施,是飞机着陆和减速滑行的区域,通过视觉定位方法计算飞机相对跑道的位置,可以作为辅助飞机快速平稳着陆的一种思路。视觉传感器所需成本较低,对安装环境要求不高,本文旨在设计一个仅靠视觉传感器对飞机进行定位的辅助着陆系统,运用目标检测和视觉定位两个模型,计算飞机相对跑道的位置。首先搭建出等比例微缩的机场跑道模型,视觉传感器产生运动模拟飞机飞行路径,目标检测模型通过机载视觉传感器获取的图像识别出跑道区域,随后视觉定位模型提取图像中跑道区域特征点,计算飞机相对跑道的位置。分别对目标检测和视觉定位两部分的实现原理及难点进行阐述,尝试将目标检测和视觉定位结合起来实现飞机降落时的定位,描述辅助着陆系统设计的整体思路。     

大型客机起飞着陆过程噪声辐射特性对比分析

 基于准稳态假设和分布点声源模型,并采用最新发展的噪声源半经验参数预测公式,发展和完善了用于飞机飞行过程中噪声辐射预测的计算模型和方法。该计算方法能够预测飞机起飞、着陆过程中的适航噪声,并能够对飞机不同噪声源的噪声辐射特性（声级、频谱特性和指向性等）进行计算分析。以某大型客机为对象,对飞机进场着陆过程和起飞过程中飞机噪声源进行了计算分析,计算结果表明,飞机进场着陆和起飞过程中,不同噪声源对远场噪声级的影响有明显的差异,起飞过程中发动机风扇噪声源是最主要的噪声辐射源,而在进场着陆过程中飞机机体噪声（包括起落架和襟翼等）是重要的飞机噪声源。文中也给出了不同噪声源频谱特性和指向特性等。     

Wind detection in a microcosm: Ship/aircraft environment sensors

One of the most demanding aspects of a Navy helicopter pilot's job is landing his aircraft on the flight deck of a pitching, rolling, heaving and yawing ship. The complex airwake velocity field associated with the ship and aircraft interface directly affects the pilot's ability to control the aircraft during takeoff, approach, hover, landing, and deck operations. Dynamic Interface (DI) testing is performed to define safe aircraft operational envelopes; however, not all conditions can be realized within the limited test period and asset/condition availability. In addition, exact wind conditions that affect the aircraft cannot be measured with existing wind sensors. These sensors measure wind in the ship's mast area which does not represent the wind flow field encountered by the aircraft. A means of non-intrusively measuring the appropriate wind data is required. This paper presents an overview of the unique aspects of the ship/aircraft interface, the overall naval DI environment and the sensor requirements for measuring this complex environment     

Prediction of noise radiation from basic configurations of landing gears by means of computational aeroacoustics

Noise radiation from aircraft during the takeoff and landing has become a major issue for inhabitants living in the vicinity of airports and thus for regulation authorities and aircraft developers. However the numerical simulation of aeroacoustic noise, especially for complex geometries like a landing gear, remains one of the most difficult challenges in aeroacoustics. The present study, aiming at predicting noise radiation from basic geometries as well as the noise radiation of a simplified landing gear, employs a hybrid approach that combines a CFD simulation with the decoupled computational aeroacoustics (CAA) simulation. Flow-induced noise is assumed to originate from turbulence. Reynolds-averaged Navier–Stokes equations with different closure approaches can be employed to gain the required turbulent quantities. Subsequently, quantities as the mean flow velocities, pressure, density, turbulent kinetic energy and dissipation rate of the CFD simulation are the starting point for the generation of the transient acoustic sources by the stochastic noise generation and radiation (SNGR) method. It is assumed that the acoustic phenomena do not provide feedback to the mean flow field and turbulence and thus a recalculation of the flow field is not required. Since the propagation of sound is insignificantly influenced by turbulent and viscous effects, it can be described by the Euler equations in the near field. The CAA simulation is extended with a Ffowcs Williams Hawkings (FWH) module that calculates the noise levels in the far field upon integrating the surface source terms on a porous FWH surface within the CAA domain. The results of the simulations are compared with experimental data, obtained by measurements in an acoustic wind tunnel.     

舰载机人工进场着舰精确轨迹控制技术

进场着舰精确轨迹控制是舰载机设计的难点和关键技术之一。首先，对舰载机人工进场着舰轨迹及精确轨迹控制的应用需求进行了讨论，指出其必要性和直观的有益效果；随后，讨论了舰载机进场着舰精确轨迹控制的演变过程、发展趋势及涉及的等角下滑航迹率控制技术、进场动力补偿技术、直接力控制技术、DP（Delta flight Path）控制技术等关键技术；最后，讨论了舰载机进场着舰精确轨迹控制对减轻驾驶员操纵负担、降低触舰点分散度、减小触舰载荷等方面的收益。研究工作对舰载机的精确轨迹着舰控制系统设计具有一定的工程指导价值。     

Magnetic Signal Processing & Analysis for Airfield Traffic Surveillance

This paper presents an innovative system for airport surface surveillance based on a novel magnetic sensing technology. Ferromagnetic objects such as vehicle motors, aircraft engines, and landing gears are detected through their deformation of the Earth's magnetic field. Tests have shown that although the local changes of the Earth's magnetic field are extremely small, the proposed sensing technology is able to detect them reliably. The primary objective of the proposed approach is to provide a complementary surveillance system for existing and future Advanced Surface Movement Guidance and Control Systems (A-SMGCS) at large airports or a cost-effective surveillance solution for monitoring critical areas at medium and small airports. Unaffected by weather conditions, interference and shadowing effects, the system provides reliable position, velocity, and direction information without requiring any equipment in aircraft or ground vehicles. The outcome of a comprehensive market analysis is discussed and test results under real life conditions at two airports are evaluated analytically.     

临近空间太阳能飞行器着陆状态阵风响应

对临近空间太阳能飞行器着陆状态时的阵风响应问题开展了数值模拟研究。针对该类飞行器质量轻、柔性大、降落时速度低的特点,基于 CFD/CSD松耦合分析法,利用网格速度法引入阵风载荷。以 1-cos阵风模型为基础,探讨了飞行器着陆状态遭遇二维阵风载荷时,其翼尖位移、扭转角、翼根所受结构整体弯矩以及升力系数的变化特性;并将二维阵风响应结果与一维阵风响应结果进行对比;获得了临近空间太阳能飞行器着陆时,二维阵风沿飞行器翼展方向的变化对其结构和气动性能的影响规律。     

A fusion and learning algorithm for landing aircraft tracking:compensating for exhaust plume disturbance

An algorithm is presented for tracking a landing aircraft using fusion of two different passive sensors, a laser range finder (LRF) and a forward-looking infrared (FLIR) camera. The main feature of this algorithm is its ability to identify and compensate for an exhaust plume disturbance. The algorithm is based on the extended Kalman filter (EKF) and the filtering confidence function (FCF) which introduces a learning approach to the tracking problem. The results of a simulation using the learning tracking algorithm and the EKF alone are presented and compared     

Space Weather and the Ground-Level Solar Proton Events of the 23rd Solar Cycle

Solar proton events can adversely affect space and ground-based systems. Ground-level events are a subset of solar proton events that have a harder spectrum than average solar proton events and are detectable on Earth’s surface by cosmic radiation ionization chambers, muon detectors, and neutron monitors. This paper summarizes the space weather effects associated with ground-level solar proton events during the 23rd solar cycle. These effects include communication and navigation systems, spacecraft electronics and operations, space power systems, manned space missions, and commercial aircraft operations. The major effect of ground-level events that affect manned spacecraft operations is increased radiation exposure. The primary effect on commercial aircraft operations is the loss of high frequency communication and, at extreme polar latitudes, an increase in the radiation exposure above that experienced from the background galactic cosmic radiation. Calculations of the maximum potential aircraft polar route exposure for each ground-level event of the 23rd solar cycle are presented. The space weather effects in October and November 2003 are highlighted together with on-going efforts to utilize cosmic ray neutron monitors to predict high energy solar proton events, thus providing an alert so that system operators can possibly make adjustments to vulnerable spacecraft operations and polar aircraft routes.     

飞机刹车系统动力模拟试验方法的探讨

针对飞机全天候起降的特性,提出了一系列地面动力模拟试验方法,更加真实地模拟飞机着陆时所处的各种跑道状态,为飞机着陆制动提供试验数据,从而提高飞机着陆的安全性和可靠性.     

民用飞机着陆灯与机场助航灯光在飞机夜航中的作用

飞机着陆灯与机场助航灯光系统为民用飞机夜航起飞、着陆提供照明,两者都十分重要。民航法规CCAR121部要求飞机必须装有至少两个着陆灯,而AC-97-FS-2011-01则要求民用机场必须配备助航灯光系统。分析了着陆灯与助航灯光两者在夜航着陆过程中的作用,并阐述两者的相互关系。     

一种着陆视觉导航P3P问题的解法

P3P问题是机器视觉领域的经典问题,其多解的排除与唯一解的确定是研究热点。针对飞行器着陆过程中机载视觉设备跑道成像的特点,提出了一种着陆视觉导航P3P问题唯一解的求解方法。该方法首先通过机场跑道的3条边线计算相对姿态,再根据直线方程求解相对位置,最终完成飞行器与跑道之间6个自由度参数的唯一确定。     

海上雾霾天气下基于能见度的舰载机目视着舰风险评估方法研究

针对雾霾天气对舰载机目视着舰安全性的影响难以量化的问题,利用激光雷达在近海的能见度观测数据,反演海上雾霾天气下飞行员目视着舰的斜程能见度的状况,提出 1种基于能见度指标的目视着舰风险评估方法,将舰载机着舰过程中飞行员频繁的目测压力,转变为舰上数据测量、风险评估和应对措施等程序化工作,将定性的安全分析转变为定量的风险评估和安全指导,谋求在现有着舰控制模式下有效降低飞行员着舰压力,提升指挥引导效率,为低能见度下舰载机目视着舰训练提供理论依据和实践指导。     

基于实测值的舰载机着舰下沉速度影响性分析

舰载机的着舰下沉速度是起落架设计的重要输入,对起落架和机体的结构重量有很大影响。为了探索舰载机使用环境下各相关参数对下沉速度的影响,基于E-2C的实测着舰数据,将多元统计学的相关分析方法应用到舰载机着舰参数影响性分析,分析了17个着舰参数与着舰下沉速度的相关性。结果表明飞机下滑角、甲板俯仰角与下沉速度呈高度相关,舰上接合速度与下沉速度呈中度相关,这三者对下沉速度有很大影响;并进一步对这4个着舰参数进行非线性回归分析,拟合了E-2C着舰下沉速度的计算式,所得回归模型决定系数为0.991,平均绝对误差为1.66%,拟合效果很好。     

飞机起落架气动噪声特性仿真与试验

 对某型飞机前起落架的气动噪声特性进行了数值仿真分析和声学风洞试验研究。在典型飞机着陆速度下,采用分离涡(DES)方法模拟起落架周围非定常湍流流场,通过涡声理论计算声源的强度和位置,并利用FW-H(Ffowcs-Williams/Hawkings)方程积分外推法求解出不同部件及其组合件产生的声场,分析其噪声的产生机制、频谱特性及远场指向特性,同时评估各部件对总噪声的贡献量。在声学风洞中对轮胎和轮叉组合件进行气动声学试验,借助麦克风测量获得了噪声的频谱特性。基于部件固体表面积分计算的仿真结果与试验结果在声学远场条件下吻合较好。仿真结果表明:起落架气动噪声是钝体绕流噪声和空腔噪声的叠加,呈现宽频噪声的特性。强度最大的声源主要分布在起落架各部件的固体表面;轮胎噪声对总噪声的贡献最大,其次是轮叉噪声,支柱噪声对总噪声贡献最小。各部件噪声和总噪声均具有偶极子声源的辐射特性。空间可穿透积分面计算的声压级结果比固体表面计算的声压级结果大5 dB左右。该研究结果为低噪声起落架设计提供了一定的参考。     

考虑杆臂效应与挠曲变形的全自动着舰技术

联合精确进近和着陆系统（JPALS）舰载组件旨在为最终进近阶段的舰载机提供自动着舰能力。针对由于舰船杆臂效应与挠曲变形的存在导致舰载机着舰定位精度下降的问题,开发了一种基于卫星引导的全自动着舰非线性化参数误差模型,结合舰船甲板运动及舰载机纵向飞行控制模型,评估舰船结构挠曲和姿态不确定性对着舰落点精度的影响。结果表明,杆臂效应与挠曲变形对着舰落点精度有显著影响,利用建立的误差模型以及飞行控制模型,能够将着舰落点精度有效控制在着舰标准之内。