control system design astrom-ch7

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[紧随时间的脚步]紧随公司脚步

[紧随时间的脚步]紧随公司脚步为时间导航——浪琴A-7型空中导航腕表浪琴A-7型空中导航腕表(LonginesAvigationTypeA-7)与此前发布的1942HeritageChronograph和MonopusherxxxxRAPH180thAnniversaryLE两款腕表一样，是为庆祝浪琴成立180周年而特别推出的纪念版腕表。

这款A-7型空中导航腕表灵感来源于20世纪30年代浪琴受美军委托制作的飞行员专用腕表。

在沿用美军命名的A-7型号之外，浪琴给这个以当代眼光重新诠释的新款加上了“空中导航”的名称。

浪琴A-7型空中导航表单按钮计时秒表款式以一种活泼的优雅夺人眼球。

直径49毫米的精钢表壳，内置专为浪琴设计的导柱轮机芯L788。

各种计时功能：启动、停止、归零均能通过按动表冠内的单按钮实现。

飞行员用表的设计，向右倾斜50度的表盘，白色的大阿拉伯数字时刻，这些都构成了这款手表的鲜明特征，这样的设计无疑也是为了方便飞行员在无需挪动手臂或放开操作杆的情况下，即可读取时间。

此外，打开浪琴A-7型空中导航表的后盖，透过蓝宝石水晶表背，你可以欣赏到这款表内部的精妙运作。

聆听时间的声音——卡地亚陀飞轮三问腕表三问，这种独特的机械报时功能，与陀飞轮、万年历并列，从来被称为机械制表的三大复杂功能，一直占据着制表工艺的最高宝座。

其稀有性、高品质的制作工艺、美妙的声音效果始终被众多喜爱美好事物的人们极力追捧。

后起之秀的卡地亚高级制表研发部迎难而上，立志为高级钟表爱好者打造一款既拥有经典外观设计，又凝聚深度声学研究成果的三问腕表。

于是2012年卡地亚的首款RotondedeCartier浮动式陀飞轮三问腕表应运而生。

能够用声响报告时间的腕表被称为“问表”，所谓“问”自然包含主动寻求的意味，意思是只有启动报时装置才能够发出声响，否则就会无声无息地运转，与普通腕表并无二致。

这个“问”的启动装置通常是表壳侧面的一个拨柄或者按钮，拨动它时就带动音锤敲击环形簧条发出声响来告知时间。

科学研究：探索宇宙奥秘的重要实验仪器

科学研究：探索宇宙奥秘的重要实验仪器介绍科学研究是人类认识自然、探索宇宙奥秘的重要途径之一。

在科学研究中，实验仪器是不可或缺的工具。

实验仪器通过设计精密的实验装置和进行各种测量，帮助科学家收集数据、验证理论以及发现新现象。

本文将介绍几个在探索宇宙奥秘方面起到重要作用的实验仪器。

1. 哈勃太空望远镜（Hubble Space Telescope）哈勃太空望远镜是一颗位于地球轨道上的巡天望远镜，由美国航天局（NASA）与欧洲空间局（ESA）合作开发和运营。

该望远镜于1990年发射升空，主要用于观测遥远星系、行星、星云等天体，以及研究黑洞、暗物质等宇宙物理现象。

哈勃太空望远镜拥有出色的光学性能和极高的分辨率，为天文学家提供了大量珍贵的数据，对宇宙起源、演化以及暗能量等重要问题的研究做出了巨大贡献。

2. 大型强子对撞机（Large Hadron Collider，LHC）大型强子对撞机是位于瑞士和法国边界的地下环形粒子加速器，由欧洲核子研究组织（CERN）建造和运营。

LHC主要用于模拟宇宙起源时期的高能条件，在极小的时间间隔内使粒子进行高速碰撞，并通过探测器观测并记录碰撞产生的粒子行为。

这些实验可以帮助科学家理解基本粒子、核物理、暗物质等重要问题，以及验证现有理论模型或发现新的物理现象。

3. 非线性光学显微成像（Nonlinear Optical Microscopy）非线性光学显微成像是一种基于激光技术的高分辨率成像方法，被用于观察和研究微观天体、生物分子以及材料结构等领域。

相比传统的荧光显微镜，非线性光学显微成像具有更高的分辨率和更好的深度探测能力。

这项技术通过激光与样品相互作用，利用非线性效应生成特定波长的光信号，并通过显微成像系统进行捕捉和分析。

4. 平面偏振光测量仪（Polarimeter）平面偏振光测量仪是一种用于测量光波偏振特性的实验装置。

通过将光与一系列特殊材料或器件相互作用，平面偏振光测量仪可以测量光传播方向、偏振状态以及旋转角度等参数。

神七科技降凡尘

神七科技降凡尘宇航员的专用睡床，如今已不再“专用”，普通百姓花28万元也可享受到同样的高质量睡眠；宇航员的防护耳塞已不再仅用于太空，当你乘飞机、游泳或者去迪厅时，也可戴上它来减压、防水和降噪；就连宇航员在太空中使用的高科技马桶，也将开发民用功能服务于特殊人群……“神七”上的高科技正在以一副更亲和的面孔走进百姓生活。

太空床：睡眠中迅速恢复体力航天特性：它可以模拟太空中的零压力环境，轨道式的电子控制驱动系统还可让航天员在床上习惯飞船座舱中的窝坐状态。

衍生功用：睡个舒舒服服的好觉是很多人的愿望，躺在航天员专用床上，身体朝下一侧每个点都能完全贴合到床上，不仅舒服，还可达到迅速恢复体力的效果。

“这种‘零压力’健康睡床是专门为‘神七’航天员设计的，不仅可以模拟太空中的零压力环境，其轨道式的电子控制驱动系统，还可让航天员在床上习惯飞船座舱中的窝坐状态。

”刚刚结束的珠海航空博览会上，太空床吸引了很多人的关注。

航天员在训练时需要承受大于一般人十几倍的压力，体力消耗巨大，因此，让他们在训练后迅速恢复体力尤为重要。

据工作人员介绍，“零压力”健康睡床就具有这样的效果。

它使用的床垫是一种非常特别的材料，单坐在任何一个点上，整张床看起来就是一个人窝在那里；但是躺平后，身体朝下一侧的每个点都能完全贴合到床上，不仅舒服还可以达到迅速恢复体力的效果。

就连床垫中使用的海绵也不是普通的海绵，是用天然树脂加工而成的，具有吸汗、防螨、永不变形等特点，还散发着天然的香气。

据了解，在“神七”升空之前，航天员在这样的太空床上睡了一年多。

除了航天员，包括姚明、刘翔、王治郅这样的奥运选手也都是这种床的忠实拥趸。

如此高级的床自然价格不菲，单是一个枕头就要1600元，普通双人床垫要价8万元，而一套与航天员用床同样规格的双人床就要28万元。

别看价格高，市场反应却不差，据说，这床在北京半个月的销售额已经超过了200万元。

太空耳塞：兼具减噪、降压、防水功能航天特性：这种航天防护耳塞是由遴选出的贴近人体组织结构的特殊材料制成的，经过了严格的压力和使用效果测试，并能与耳道自动吻合，戴上没有压迫感。

5“神七”的七大系统

神七飞天七大系统全解读航天员系统航天员经过5级筛选，从1506名空军飞行员中挑选出来。

飞船应用系统神七将搭载灵芝、平菇、虫草、双孢蘑菇、杏鲍菇、茶树菇等6种微生物菌种和两种杂交水稻上天进行科学实验。

轨道舱轨道舱为圆柱形，是飞船进入轨道后航天员工作、生活的场所。

舱内除备有食物、饮水和大小便收集器等生活装置外，还有空间应用和科学试验用的仪器设备，神七飞船轨道舱是“一舱两用”，内有一“夹层”作为气闸舱。

运载火箭系统承担“神七”发射任务的是长征二号F火箭，火箭上安装了3个摄像头，可清楚地看到火箭发射飞行全过程。

另外火箭增加了一个电能量蓄压器，能把火箭的震动给减小，航天员会乘坐得更舒服。

发射场系统酒泉卫星发射中心对发射塔架上航天员逃逸滑带进行了更新，在火箭点火后，如发生意外，航天员可以启动逃逸飞行器，逃逸系统将带着飞船离开箭体，在安全地区着陆。

航天测控与通信系统为确保神七及后续航天试验任务顺利进行，我国在各大海域布阵了五艘测量船，另外，中国首颗数据中继卫星“天链一号01星”，将在神七飞行中首次应用，届时，飞船的测控覆盖率将由原来的12％大幅提高到60％左右。

着陆场系统主着陆场的搜救及医疗保障全部依靠直升机，而不再采用地面车辆搜救。

神七还首次使用应急救生辅助决策系统，只要在电脑中输入发生应急情况的时间，系统就能自动生成救生方案。

返回舱返回舱呈钟形，舱门与轨道舱相通。

返回舱是飞船的指挥控制中心，内设可供3名航天员斜躺的座椅，供航天员起飞、上升和返回阶段乘坐。

座椅前下方是仪表板、手控操纵手柄和光学瞄准镜等，显示飞船上各系统机器设备的状况。

推进舱推进舱又称设备舱，呈圆柱形，内部装载推进系统的发动机和推进剂，为飞船提供调整姿态和轨道以及制动减速所需要的动力，还有电源、环境控制和通信等系统的部分设备。

Laser Ranging to the Moon, Mars and Beyond

a r X i v :g r -q c /0411082v 1 16 N o v 2004Laser Ranging to the Moon,Mars and BeyondSlava G.Turyshev,James G.Williams,Michael Shao,John D.AndersonJet Propulsion Laboratory,California Institute of Technology,4800Oak Grove Drive,Pasadena,CA 91109,USAKenneth L.Nordtvedt,Jr.Northwest Analysis,118Sourdough Ridge Road,Bozeman,MT 59715USA Thomas W.Murphy,Jr.Physics Department,University of California,San Diego 9500Gilman Dr.,La Jolla,CA 92093USA Abstract Current and future optical technologies will aid exploration of the Moon and Mars while advancing fundamental physics research in the solar system.Technologies and possible improvements in the laser-enabled tests of various physical phenomena are considered along with a space architecture that could be the cornerstone for robotic and human exploration of the solar system.In particular,accurate ranging to the Moon and Mars would not only lead to construction of a new space communication infrastructure enabling an improved navigational accuracy,but will also provide a signiﬁcant improvement in several tests of gravitational theory:the equivalence principle,geodetic precession,PPN parameters βand γ,and possible variation of the gravitational constant G .Other tests would become possible with an optical architecture that would allow proceeding from meter to centimeter to millimeter range accuracies on interplanetary distances.This paper discusses the current state and the future improvements in the tests of relativistic gravity with Lunar Laser Ranging (LLR).We also consider precision gravitational tests with the future laser rangingto Mars and discuss optical design of the proposed Laser Astrometric Test of Relativity (LATOR)mission.We emphasize that already existing capabilities can oﬀer signiﬁcant improvements not only in the tests of fundamental physics,but may also establish the infrastructure for space exploration in the near future.Looking to future exploration,what characteristics are desired for the next generation of ranging devices,what is the optimal architecture that would beneﬁt both space exploration and fundamental physics,and what fundamental questions can be investigated?We try to answer these questions.1IntroductionThe recent progress in fundamental physics research was enabled by signiﬁcant advancements in many technological areas with one of the examples being the continuing development of the NASA Deep Space Network –critical infrastructure for precision navigation and communication in space.A demonstration of such a progress is the recent Cassini solar conjunction experiment[8,6]that was possible only because of the use of Ka-band(∼33.4GHz)spacecraft radio-tracking capabilities.The experiment was part of the ancillary science program–a by-product of this new radio-tracking technology.Becasue of a much higher data rate transmission and, thus,larger data volume delivered from large distances the higher communication frequency was a very important mission capability.The higher frequencies are also less aﬀected by the dispersion in the solar plasma,thus allowing a more extensive coverage,when depp space navigation is concerned.There is still a possibility of moving to even higher radio-frequencies, say to∼60GHz,however,this would put us closer to the limit that the Earth’s atmosphere imposes on signal transmission.Beyond these frequencies radio communication with distant spacecraft will be ineﬃcient.The next step is switching to optical communication.Lasers—with their spatial coherence,narrow spectral emission,high power,and well-deﬁned spatial modes—are highly useful for many space applications.While in free-space,optical laser communication(lasercomm)would have an advantage as opposed to the conventional radio-communication sercomm would provide not only signiﬁcantly higher data rates(on the order of a few Gbps),it would also allow a more precise navigation and attitude control.The latter is of great importance for manned missions in accord the“Moon,Mars and Beyond”Space Exploration Initiative.In fact,precision navigation,attitude control,landing,resource location, 3-dimensional imaging,surface scanning,formationﬂying and many other areas are thought only in terms of laser-enabled technologies.Here we investigate how a near-future free-space optical communication architecture might beneﬁt progress in gravitational and fundamental physics experiments performed in the solar system.This paper focuses on current and future optical technologies and methods that will advance fundamental physics research in the context of solar system exploration.There are many activities that focused on the design on an optical transceiver system which will work at the distance comparable to that between the Earth and Mars,and test it on the Moon.This paper summarizes required capabilities for such a system.In particular,we discuss how accurate laser ranging to the neighboring celestial bodies,the Moon and Mars,would not only lead to construction of a new space communication infrastructure with much improved navigational accuracy,it will also provide a signiﬁcant improvement in several tests of gravitational theory. Looking to future exploration,we address the characteristics that are desired for the next generation of ranging devices;we will focus on optimal architecture that would beneﬁt both space exploration and fundamental physics,and discuss the questions of critical importance that can be investigated.This paper is organized as follows:Section2discusses the current state and future per-formance expected with the LLR technology.Section3addresses the possibility of improving tests of gravitational theories with laser ranging to Mars.Section4addresses the next logical step—interplanetary laser ranging.We discuss the mission proposal for the Laser Astrometric Test of Relativity(LATOR).We present a design for its optical receiver system.Section5 addresses a proposal for new multi-purpose space architecture based on optical communica-tion.We present a preliminary design and discuss implications of this new proposal for tests of fundamental physics.We close with a summary and recommendations.2LLR Contribution to Fundamental PhysicsDuring more than35years of its existence lunar laser ranging has become a critical technique available for precision tests of gravitational theory.The20th century progress in three seem-ingly unrelated areas of human exploration–quantum optics,astronomy,and human spaceexploration,led to the construction of this unique interplanetary instrument to conduct very precise tests of fundamental physics.In this section we will discuss the current state in LLR tests of relativistic gravity and explore what could be possible in the near future.2.1Motivation for Precision Tests of GravityThe nature of gravity is fundamental to our understanding of the structure and evolution of the universe.This importance motivates various precision tests of gravity both in laboratories and in space.Most of the experimental underpinning for theoretical gravitation has come from experiments conducted in the solar system.Einstein’s general theory of relativity(GR)began its empirical success in1915by explaining the anomalous perihelion precession of Mercury’s orbit,using no adjustable theoretical parameters.Eddington’s observations of the gravitational deﬂection of light during a solar eclipse in1919conﬁrmed the doubling of the deﬂection angles predicted by GR as compared to Newtonian and Equivalence Principle(EP)arguments.Follow-ing these beginnings,the general theory of relativity has been veriﬁed at ever-higher accuracy. Thus,microwave ranging to the Viking landers on Mars yielded an accuracy of∼0.2%from the gravitational time-delay tests of GR[48,44,49,50].Recent spacecraft and planetary mi-crowave radar observations reached an accuracy of∼0.15%[4,5].The astrometric observations of the deﬂection of quasar positions with respect to the Sun performed with Very-Long Base-line Interferometry(VLBI)improved the accuracy of the tests of gravity to∼0.045%[45,51]. Lunar Laser Ranging(LLR),the continuing legacy of the Apollo program,has provided ver-iﬁcation of GR improving an accuracy to∼0.011%via precision measurements of the lunar orbit[62,63,30,31,32,35,24,36,4,68].The recent time-delay experiments with the Cassini spacecraft at a solar conjunction have tested gravity to a remarkable accuracy of0.0023%[8] in measuring deﬂection of microwaves by solar gravity.Thus,almost ninety years after general relativity was born,Einstein’s theory has survived every test.This rare longevity and the absence of any adjustable parameters,does not mean that this theory is absolutely correct,but it serves to motivate more sensitive tests searching for its expected violation.The solar conjunction experiments with the Cassini spacecraft have dramatically improved the accuracy in the solar system tests of GR[8].The reported accuracy of2.3×10−5in measuring the Eddington parameterγ,opens a new realm for gravitational tests,especially those motivated by the on-going progress in scalar-tensor theories of gravity.1 In particular,scalar-tensor extensions of gravity that are consistent with present cosmological models[15,16,17,18,19,20,39]predict deviations of this parameter from its GR value of unity at levels of10−5to10−7.Furthermore,the continuing inability to unify gravity with the other forces indicates that GR should be violated at some level.The Cassini result together with these theoretical predictions motivate new searches for possible GR violations;they also provide a robust theoretical paradigm and constructive guidance for experiments that would push beyond the present experimental accuracy for parameterized post-Newtonian(PPN)parameters(for details on the PPN formalism see[60]).Thus,in addition to experiments that probe the GR prediction for the curvature of the gravityﬁeld(given by parameterγ),any experiment pushingthe accuracy in measuring the degree of non-linearity of gravity superposition(given by anotherEddington parameterβ)will also be of great interest.This is a powerful motive for tests ofgravitational physics phenomena at improved accuracies.Analyses of laser ranges to the Moon have provided increasingly stringent limits on anyviolation of the Equivalence Principle(EP);they also enabled very accurate measurements fora number of relativistic gravity parameters.2.2LLR History and Scientiﬁc BackgroundLLR has a distinguished history[24,9]dating back to the placement of a retroreﬂector array onthe lunar surface by the Apollo11astronauts.Additional reﬂectors were left by the Apollo14and Apollo15astronauts,and two French-built reﬂector arrays were placed on the Moon by theSoviet Luna17and Luna21missions.Figure1shows the weighted RMS residual for each year.Early accuracies using the McDonald Observatory’s2.7m telescope hovered around25cm. Equipment improvements decreased the ranging uncertainty to∼15cm later in the1970s.In1985the2.7m ranging system was replaced with the McDonald Laser Ranging System(MLRS).In the1980s ranges were also received from Haleakala Observatory on the island of Maui in theHawaiian chain and the Observatoire de la Cote d’Azur(OCA)in France.Haleakala ceasedoperations in1990.A sequence of technical improvements decreased the range uncertainty tothe current∼2cm.The2.7m telescope had a greater light gathering capability than thenewer smaller aperture systems,but the newer systemsﬁred more frequently and had a muchimproved range accuracy.The new systems do not distinguish returning photons against thebright background near full Moon,which the2.7m telescope could do,though there are somemodern eclipse observations.The lasers currently used in the ranging operate at10Hz,with a pulse width of about200 psec;each pulse contains∼1018photons.Under favorable observing conditions a single reﬂectedphoton is detected once every few seconds.For data processing,the ranges represented by thereturned photons are statistically combined into normal points,each normal point comprisingup to∼100photons.There are15553normal points are collected until March2004.Themeasured round-trip travel times∆t are two way,but in this paper equivalent ranges in lengthunits are c∆t/2.The conversion between time and length(for distance,residuals,and dataaccuracy)uses1nsec=15cm.The ranges of the early1970s had accuracies of approximately25cm.By1976the accuracies of the ranges had improved to about15cm.Accuracies improvedfurther in the mid-1980s;by1987they were4cm,and the present accuracies are∼2cm.One immediate result of lunar ranging was the great improvement in the accuracy of the lunarephemeris[62]and lunar science[67].LLR measures the range from an observatory on the Earth to a retroreﬂector on the Moon. For the Earth and Moon orbiting the Sun,the scale of relativistic eﬀects is set by the ratio(GM/rc2)≃v2/c2∼10−8.The center-to-center distance of the Moon from the Earth,with mean value385,000km,is variable due to such things as eccentricity,the attraction of the Sun,planets,and the Earth’s bulge,and relativistic corrections.In addition to the lunar orbit,therange from an observatory on the Earth to a retroreﬂector on the Moon depends on the positionin space of the ranging observatory and the targeted lunar retroreﬂector.Thus,orientation ofthe rotation axes and the rotation angles of both bodies are important with tidal distortions,plate motion,and relativistic transformations also coming into play.To extract the gravitationalphysics information of interest it is necessary to accurately model a variety of eﬀects[68].For a general review of LLR see[24].A comprehensive paper on tests of gravitationalphysics is[62].A recent test of the EP is in[4]and other GR tests are in[64].An overviewFigure1:Historical accuracy of LLR data from1970to2004.of the LLR gravitational physics tests is given by Nordtvedt[37].Reviews of various tests of relativity,including the contribution by LLR,are given in[58,60].Our recent paper describes the model improvements needed to achieve mm-level accuracy for LLR[66].The most recent LLR results are given in[68].2.3Tests of Relativistic Gravity with LLRLLR oﬀers very accurate laser ranging(weighted rms currently∼2cm or∼5×10−11in frac-tional accuracy)to retroreﬂectors on the Moon.Analysis of these very precise data contributes to many areas of fundamental and gravitational physics.Thus,these high-precision studies of the Earth-Moon-Sun system provide the most sensitive tests of several key properties of weak-ﬁeld gravity,including Einstein’s Strong Equivalence Principle(SEP)on which general relativity rests(in fact,LLR is the only current test of the SEP).LLR data yielded the strongest limits to date on variability of the gravitational constant(the way gravity is aﬀected by the expansion of the universe),and the best measurement of the de Sitter precession rate.In this Section we discuss these tests in more details.2.3.1Tests of the Equivalence PrincipleThe Equivalence Principle,the exact correspondence of gravitational and inertial masses,is a central assumption of general relativity and a unique feature of gravitation.EP tests can therefore be viewed in two contexts:tests of the foundations of general relativity,or as searches for new physics.As emphasized by Damour[12,13],almost all extensions to the standard modelof particle physics(with best known extension oﬀered by string theory)generically predict newforces that would show up as apparent violations of the EP.The weak form the EP(the WEP)states that the gravitational properties of strong and electro-weak interactions obey the EP.In this case the relevant test-body diﬀerences are their fractional nuclear-binding diﬀerences,their neutron-to-proton ratios,their atomic charges,etc. General relativity,as well as other metric theories of gravity,predict that the WEP is exact. However,extensions of the Standard Model of Particle Physics that contain new macroscopic-range quantumﬁelds predict quantum exchange forces that will generically violate the WEP because they couple to generalized‘charges’rather than to mass/energy as does gravity[17,18]. WEP tests can be conducted with laboratory or astronomical bodies,because the relevant diﬀerences are in the test-body compositions.Easily the most precise tests of the EP are made by simply comparing the free fall accelerations,a1and a2,of diﬀerent test bodies.For the case when the self-gravity of the test bodies is negligible and for a uniform external gravityﬁeld, with the bodies at the same distance from the source of the gravity,the expression for the Equivalence Principle takes the most elegant form:∆a= M G M I 2(1)(a1+a2)where M G and M I represent gravitational and inertial masses of each body.The sensitivity of the EP test is determined by the precision of the diﬀerential acceleration measurement divided by the degree to which the test bodies diﬀer(position).The strong form of the EP(the SEP)extends the principle to cover the gravitational properties of gravitational energy itself.In other words it is an assumption about the way that gravity begets gravity,i.e.about the non-linear property of gravitation.Although general relativity assumes that the SEP is exact,alternate metric theories of gravity such as those involving scalarﬁelds,and other extensions of gravity theory,typically violate the SEP[30,31, 32,35].For the SEP case,the relevant test body diﬀerences are the fractional contributions to their masses by gravitational self-energy.Because of the extreme weakness of gravity,SEP test bodies that diﬀer signiﬁcantly must have astronomical sizes.Currently the Earth-Moon-Sun system provides the best arena for testing the SEP.The development of the parameterized post-Newtonian formalism[31,56,57],allows one to describe within the common framework the motion of celestial bodies in external gravitational ﬁelds within a wide class of metric theories of gravity.Over the last35years,the PPN formalism has become a useful framework for testing the SEP for extended bodies.In that formalism,the ratio of passive gravitational to inertial mass to theﬁrst order is given by[30,31]:M GMc2 ,(2) whereηis the SEP violation parameter(discussed below),M is the mass of a body and E is its gravitational binding or self-energy:E2Mc2 V B d3x d3yρB(x)ρB(y)EMc2 E=−4.64×10−10andwhere the subscripts E and m denote the Earth and Moon,respectively.The relatively small size bodies used in the laboratory experiments possess a negligible amount of gravitational self-energy and therefore such experiments indicate nothing about the equality of gravitational self-energy contributions to the inertial and passive gravitational masses of the bodies [30].TotesttheSEP onemustutilize planet-sizedextendedbodiesinwhichcase theratioEq.(3)is considerably higher.Dynamics of the three-body Sun-Earth-Moon system in the solar system barycentric inertial frame was used to search for the eﬀect of a possible violation of the Equivalence Principle.In this frame,the quasi-Newtonian acceleration of the Moon (m )with respect to the Earth (E ),a =a m −a E ,is calculated to be:a =−µ∗rM I m µS r SEr 3Sm + M G M I m µS r SEr 3+µS r SEr 3Sm +η E Mc 2 m µS r SEMc 2 E − E n 2−(n −n ′)2n ′2a ′cos[(n −n ′)t +D 0].(8)Here,n denotes the sidereal mean motion of the Moon around the Earth,n ′the sidereal mean motion of the Earth around the Sun,and a ′denotes the radius of the orbit of the Earth around the Sun (assumed circular).The argument D =(n −n ′)t +D 0with near synodic period is the mean longitude of the Moon minus the mean longitude of the Sun and is zero at new Moon.(For a more precise derivation of the lunar range perturbation due to the SEP violation acceleration term in Eq.(6)consult [62].)Any anomalous radial perturbation will be proportional to cos D .Expressed in terms ofη,the radial perturbation in Eq.(8)isδr∼13ηcos D meters [38,21,22].This eﬀect,generalized to all similar three body situations,the“SEP-polarization eﬀect.”LLR investigates the SEP by looking for a displacement of the lunar orbit along the direction to the Sun.The equivalence principle can be split into two parts:the weak equivalence principle tests the sensitivity to composition and the strong equivalence principle checks the dependence on mass.There are laboratory investigations of the weak equivalence principle(at University of Washington)which are about as accurate as LLR[7,1].LLR is the dominant test of the strong equivalence principle.The most accurate test of the SEP violation eﬀect is presently provided by LLR[61,48,23],and also in[24,62,63,4].Recent analysis of LLR data test the EP of∆(M G/M I)EP=(−1.0±1.4)×10−13[68].This result corresponds to a test of the SEP of∆(M G/M I)SEP=(−2.0±2.0)×10−13with the SEP violation parameter η=4β−γ−3found to beη=(4.4±4.5)×10−ing the recent Cassini result for the PPN parameterγ,PPN parameterβis determined at the level ofβ−1=(1.2±1.1)×10−4.2.3.2Other Tests of Gravity with LLRLLR data yielded the strongest limits to date on variability of the gravitational constant(the way gravity is aﬀected by the expansion of the universe),the best measurement of the de Sitter precession rate,and is relied upon to generate accurate astronomical ephemerides.The possibility of a time variation of the gravitational constant,G,wasﬁrst considered by Dirac in1938on the basis of his large number hypothesis,and later developed by Brans and Dicke in their theory of gravitation(for more details consult[59,60]).Variation might be related to the expansion of the Universe,in which case˙G/G=σH0,where H0is the Hubble constant, andσis a dimensionless parameter whose value depends on both the gravitational constant and the cosmological model considered.Revival of interest in Brans-Dicke-like theories,with a variable G,was partially motivated by the appearance of superstring theories where G is considered to be a dynamical quantity[26].Two limits on a change of G come from LLR and planetary ranging.This is the second most important gravitational physics result that LLR provides.GR does not predict a changing G,but some other theories do,thus testing for this eﬀect is important.The current LLR ˙G/G=(4±9)×10−13yr−1is the most accurate limit published[68].The˙G/G uncertaintyis83times smaller than the inverse age of the universe,t0=13.4Gyr with the value for Hubble constant H0=72km/sec/Mpc from the WMAP data[52].The uncertainty for˙G/G is improving rapidly because its sensitivity depends on the square of the data span.This fact puts LLR,with its more then35years of history,in a clear advantage as opposed to other experiments.LLR has also provided the only accurate determination of the geodetic precession.Ref.[68]reports a test of geodetic precession,which expressed as a relative deviation from GR,is K gp=−0.0019±0.0064.The GP-B satellite should provide improved accuracy over this value, if that mission is successfully completed.LLR also has the capability of determining PPNβandγdirectly from the point-mass orbit perturbations.A future possibility is detection of the solar J2from LLR data combined with the planetary ranging data.Also possible are dark matter tests,looking for any departure from the inverse square law of gravity,and checking for a variation of the speed of light.The accurate LLR data has been able to quickly eliminate several suggested alterations of physical laws.The precisely measured lunar motion is a reality that any proposed laws of attraction and motion must satisfy.The above investigations are important to gravitational physics.The future LLR data will improve the above investigations.Thus,future LLR data of current accuracy would con-tinue to shrink the uncertainty of˙G because of the quadratic dependence on data span.The equivalence principle results would improve more slowly.To make a big improvement in the equivalence principle uncertainty requires improved range accuracy,and that is the motivation for constructing the APOLLO ranging facility in New Mexico.2.4Future LLR Data and APOLLO facilityIt is essential that acquisition of the new LLR data will continue in the future.Accuracies∼2cm are now achieved,and further very useful improvement is expected.Inclusion of improved data into LLR analyses would allow a correspondingly more precise determination of the gravitational physics parameters under study.LLR has remained a viable experiment with fresh results over35years because the data accuracies have improved by an order of magnitude(see Figure1).There are prospects for future LLR station that would provide another order of magnitude improvement.The Apache Point Observatory Lunar Laser-ranging Operation(APOLLO)is a new LLR eﬀort designed to achieve mm range precision and corresponding order-of-magnitude gains in measurements of fundamental physics parameters.For theﬁrst time in the LLR history,using a3.5m telescope the APOLLO facility will push LLR into a new regime of multiple photon returns with each pulse,enabling millimeter range precision to be achieved[29,66].The anticipated mm-level range accuracy,expected from APOLLO,has a potential to test the EP with a sensitivity approaching10−14.This accuracy would yield sensitivity for parameterβat the level of∼5×10−5and measurements of the relative change in the gravitational constant,˙G/G, would be∼0.1%the inverse age of the universe.The overwhelming advantage APOLLO has over current LLR operations is a3.5m astro-nomical quality telescope at a good site.The site in southern New Mexico oﬀers high altitude (2780m)and very good atmospheric“seeing”and image quality,with a median image resolu-tion of1.1arcseconds.Both the image sharpness and large aperture conspire to deliver more photons onto the lunar retroreﬂector and receive more of the photons returning from the re-ﬂectors,pared to current operations that receive,on average,fewer than0.01 photons per pulse,APOLLO should be well into the multi-photon regime,with perhaps5–10 return photons per pulse.With this signal rate,APOLLO will be eﬃcient atﬁnding and track-ing the lunar return,yielding hundreds of times more photons in an observation than current√operations deliver.In addition to the signiﬁcant reduction in statistical error(useful).These new reﬂectors on the Moon(and later on Mars)can oﬀer signiﬁcant navigational accuracy for many space vehicles on their approach to the lunar surface or during theirﬂight around the Moon,but they also will contribute signiﬁcantly to fundamental physics research.The future of lunar ranging might take two forms,namely passive retroreﬂectors and active transponders.The advantages of new installations of passive retroreﬂector arrays are their long life and simplicity.The disadvantages are the weak returned signal and the spread of the reﬂected pulse arising from lunar librations(apparent changes in orientation of up to10 degrees).Insofar as the photon timing error budget is dominated by the libration-induced pulse spread—as is the case in modern lunar ranging—the laser and timing system parameters do√not inﬂuence the net measurement uncertainty,which simply scales as1/3Laser Ranging to MarsThere are three diﬀerent experiments that can be done with accurate ranges to Mars:a test of the SEP(similar to LLR),a solar conjunction experiment measuring the deﬂection of light in the solar gravity,similar to the Cassini experiment,and a search for temporal variation in the gravitational constant G.The Earth-Mars-Sun-Jupiter system allows for a sensitive test of the SEP which is qualitatively diﬀerent from that provided by LLR[3].Furthermore,the outcome of these ranging experiments has the potential to improve the values of the two relativistic parameters—a combination of PPN parametersη(via test of SEP)and a direct observation of the PPN parameterγ(via Shapiro time delay or solar conjunction experiments).(This is quite diﬀerent compared to LLR,as the small variation of Shapiro time delay prohibits very accurate independent determination of the parameterγ).The Earth-Mars range would also provide for a very accurate test of˙G/G.This section qualitatively addresses the near-term possibility of laser ranging to Mars and addresses the above three eﬀects.3.1Planetary Test of the SEP with Ranging to MarsEarth-Mars ranging data can provide a useful estimate of the SEP parameterηgiven by Eq.(7). It was demonstrated in[3]that if future Mars missions provide ranging measurements with an accuracy ofσcentimeters,after ten years of ranging the expected accuracy for the SEP parameterηmay be of orderσ×10−6.These ranging measurements will also provide the most accurate determination of the mass of Jupiter,independent of the SEP eﬀect test.It has been observed previously that a measurement of the Sun’s gravitational to inertial mass ratio can be performed using the Sun-Jupiter-Mars or Sun-Jupiter-Earth system[33,47,3]. The question we would like to answer here is how accurately can we do the SEP test given the accurate ranging to Mars?We emphasize that the Sun-Mars-Earth-Jupiter system,though governed basically by the same equations of motion as Sun-Earth-Moon system,is signiﬁcantly diﬀerent physically.For a given value of SEP parameterηthe polarization eﬀects on the Earth and Mars orbits are almost two orders of magnitude larger than on the lunar orbit.Below we examine the SEP eﬀect on the Earth-Mars range,which has been measured as part of the Mariner9and Viking missions with ranging accuracy∼7m[48,44,41,43].The main motivation for our analysis is the near-future Mars missions that should yield ranging data, accurate to∼1cm.This accuracy would bring additional capabilities for the precision tests of fundamental and gravitational physics.3.1.1Analytical Background for a Planetary SEP TestThe dynamics of the four-body Sun-Mars-Earth-Jupiter system in the Solar system barycentric inertial frame were considered.The quasi-Newtonian acceleration of the Earth(E)with respect to the Sun(S),a SE=a E−a S,is straightforwardly calculated to be:a SE=−µ∗SE·r SE MI Eb=M,Jµb r bS r3bE + M G M I E b=M,Jµb r bS。

Hemisphere 系列北斗高精度板卡P307用户手册2104-v1.0

第三章连接与设置 ...............................................................ห้องสมุดไป่ตู้........................... 9
3.1 加电启动 .................................................................................................................... 9 3.2 设置接收机数据输出 ................................................................................................. 9 3.2.1 THIS 端口和 OTHER 端口 ........................................................................ 10
I
3.2.2 保存当前配置 ................................................................................................ 10 3.3 配置端口 D 接收 RTCM 信息（信标或 L-BAND 功能） .................................... 11
1.1 产品概述 .................................................................................................................... 1 1.2 产品主要特点 ............................................................................................................ 1 1.3 技术规格 ..................................................................................................................... 2

Glider Flying Handbook说明书

Glider Flying Handbook2013U.S. Department of TransportationFEDERAL AVIATION ADMINISTRATIONFlight Standards Servicei iPrefaceThe Glider Flying Handbook is designed as a technical manual for applicants who are preparing for glider category rating and for currently certificated glider pilots who wish to improve their knowledge. Certificated flight instructors will find this handbook a valuable training aid, since detailed coverage of aeronautical decision-making, components and systems, aerodynamics, flight instruments, performance limitations, ground operations, flight maneuvers, traffic patterns, emergencies, soaring weather, soaring techniques, and cross-country flight is included. Topics such as radio navigation and communication, use of flight information publications, and regulations are available in other Federal Aviation Administration (FAA) publications.The discussion and explanations reflect the most commonly used practices and principles. Occasionally, the word “must” or similar language is used where the desired action is deemed critical. The use of such language is not intended to add to, interpret, or relieve a duty imposed by Title 14 of the Code of Federal Regulations (14 CFR). Persons working towards a glider rating are advised to review the references from the applicable practical test standards (FAA-G-8082-4, Sport Pilot and Flight Instructor with a Sport Pilot Rating Knowledge Test Guide, FAA-G-8082-5, Commercial Pilot Knowledge Test Guide, and FAA-G-8082-17, Recreational Pilot and Private Pilot Knowledge Test Guide). Resources for study include FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-2, Risk Management Handbook, and Advisory Circular (AC) 00-6, Aviation Weather For Pilots and Flight Operations Personnel, AC 00-45, Aviation Weather Services, as these documents contain basic material not duplicated herein. All beginning applicants should refer to FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, for study and basic library reference.It is essential for persons using this handbook to become familiar with and apply the pertinent parts of 14 CFR and the Aeronautical Information Manual (AIM). The AIM is available online at . The current Flight Standards Service airman training and testing material and learning statements for all airman certificates and ratings can be obtained from .This handbook supersedes FAA-H-8083-13, Glider Flying Handbook, dated 2003. Always select the latest edition of any publication and check the website for errata pages and listing of changes to FAA educational publications developed by the FAA’s Airman Testing Standards Branch, AFS-630.This handbook is available for download, in PDF format, from .This handbook is published by the United States Department of Transportation, Federal Aviation Administration, Airman Testing Standards Branch, AFS-630, P.O. Box 25082, Oklahoma City, OK 73125.Comments regarding this publication should be sent, in email form, to the following address:********************************************John M. AllenDirector, Flight Standards Serviceiiii vAcknowledgmentsThe Glider Flying Handbook was produced by the Federal Aviation Administration (FAA) with the assistance of Safety Research Corporation of America (SRCA). The FAA wishes to acknowledge the following contributors: Sue Telford of Telford Fishing & Hunting Services for images used in Chapter 1JerryZieba () for images used in Chapter 2Tim Mara () for images used in Chapters 2 and 12Uli Kremer of Alexander Schleicher GmbH & Co for images used in Chapter 2Richard Lancaster () for images and content used in Chapter 3Dave Nadler of Nadler & Associates for images used in Chapter 6Dave McConeghey for images used in Chapter 6John Brandon (www.raa.asn.au) for images and content used in Chapter 7Patrick Panzera () for images used in Chapter 8Jeff Haby (www.theweatherprediction) for images used in Chapter 8National Soaring Museum () for content used in Chapter 9Bill Elliot () for images used in Chapter 12.Tiffany Fidler for images used in Chapter 12.Additional appreciation is extended to the Soaring Society of America, Inc. (), the Soaring Safety Foundation, and Mr. Brad Temeyer and Mr. Bill Martin from the National Oceanic and Atmospheric Administration (NOAA) for their technical support and input.vv iPreface (iii)Acknowledgments (v)Table of Contents (vii)Chapter 1Gliders and Sailplanes ........................................1-1 Introduction....................................................................1-1 Gliders—The Early Years ..............................................1-2 Glider or Sailplane? .......................................................1-3 Glider Pilot Schools ......................................................1-4 14 CFR Part 141 Pilot Schools ...................................1-5 14 CFR Part 61 Instruction ........................................1-5 Glider Certificate Eligibility Requirements ...................1-5 Common Glider Concepts ..............................................1-6 Terminology...............................................................1-6 Converting Metric Distance to Feet ...........................1-6 Chapter 2Components and Systems .................................2-1 Introduction....................................................................2-1 Glider Design .................................................................2-2 The Fuselage ..................................................................2-4 Wings and Components .............................................2-4 Lift/Drag Devices ...........................................................2-5 Empennage .....................................................................2-6 Towhook Devices .......................................................2-7 Powerplant .....................................................................2-7 Self-Launching Gliders .............................................2-7 Sustainer Engines .......................................................2-8 Landing Gear .................................................................2-8 Wheel Brakes .............................................................2-8 Chapter 3Aerodynamics of Flight .......................................3-1 Introduction....................................................................3-1 Forces of Flight..............................................................3-2 Newton’s Third Law of Motion .................................3-2 Lift ..............................................................................3-2The Effects of Drag on a Glider .....................................3-3 Parasite Drag ..............................................................3-3 Form Drag ...............................................................3-3 Skin Friction Drag ..................................................3-3 Interference Drag ....................................................3-5 Total Drag...................................................................3-6 Wing Planform ...........................................................3-6 Elliptical Wing ........................................................3-6 Rectangular Wing ...................................................3-7 Tapered Wing .........................................................3-7 Swept-Forward Wing ..............................................3-7 Washout ..................................................................3-7 Glide Ratio .................................................................3-8 Aspect Ratio ............................................................3-9 Weight ........................................................................3-9 Thrust .........................................................................3-9 Three Axes of Rotation ..................................................3-9 Stability ........................................................................3-10 Flutter .......................................................................3-11 Lateral Stability ........................................................3-12 Turning Flight ..............................................................3-13 Load Factors .................................................................3-13 Radius of Turn ..........................................................3-14 Turn Coordination ....................................................3-15 Slips ..........................................................................3-15 Forward Slip .........................................................3-16 Sideslip .................................................................3-17 Spins .........................................................................3-17 Ground Effect ...............................................................3-19 Chapter 4Flight Instruments ...............................................4-1 Introduction....................................................................4-1 Pitot-Static Instruments ..................................................4-2 Impact and Static Pressure Lines................................4-2 Airspeed Indicator ......................................................4-2 The Effects of Altitude on the AirspeedIndicator..................................................................4-3 Types of Airspeed ...................................................4-3Table of ContentsviiAirspeed Indicator Markings ......................................4-5 Other Airspeed Limitations ........................................4-6 Altimeter .....................................................................4-6 Principles of Operation ...........................................4-6 Effect of Nonstandard Pressure andTemperature............................................................4-7 Setting the Altimeter (Kollsman Window) .............4-9 Types of Altitude ......................................................4-10 Variometer................................................................4-11 Total Energy System .............................................4-14 Netto .....................................................................4-14 Electronic Flight Computers ....................................4-15 Magnetic Compass .......................................................4-16 Yaw String ................................................................4-16 Inclinometer..............................................................4-16 Gyroscopic Instruments ...............................................4-17 G-Meter ........................................................................4-17 FLARM Collision Avoidance System .........................4-18 Chapter 5Glider Performance .............................................5-1 Introduction....................................................................5-1 Factors Affecting Performance ......................................5-2 High and Low Density Altitude Conditions ...........5-2 Atmospheric Pressure .............................................5-2 Altitude ...................................................................5-3 Temperature............................................................5-3 Wind ...........................................................................5-3 Weight ........................................................................5-5 Rate of Climb .................................................................5-7 Flight Manuals and Placards ..........................................5-8 Placards ......................................................................5-8 Performance Information ...........................................5-8 Glider Polars ...............................................................5-8 Weight and Balance Information .............................5-10 Limitations ...............................................................5-10 Weight and Balance .....................................................5-12 Center of Gravity ......................................................5-12 Problems Associated With CG Forward ofForward Limit .......................................................5-12 Problems Associated With CG Aft of Aft Limit ..5-13 Sample Weight and Balance Problems ....................5-13 Ballast ..........................................................................5-14 Chapter 6Preflight and Ground Operations .......................6-1 Introduction....................................................................6-1 Assembly and Storage Techniques ................................6-2 Trailering....................................................................6-3 Tiedown and Securing ................................................6-4Water Ballast ..............................................................6-4 Ground Handling........................................................6-4 Launch Equipment Inspection ....................................6-5 Glider Preflight Inspection .........................................6-6 Prelaunch Checklist ....................................................6-7 Glider Care .....................................................................6-7 Preventive Maintenance .............................................6-8 Chapter 7Launch and Recovery Procedures and Flight Maneuvers ............................................................7-1 Introduction....................................................................7-1 Aerotow Takeoff Procedures .........................................7-2 Signals ........................................................................7-2 Prelaunch Signals ....................................................7-2 Inflight Signals ........................................................7-3 Takeoff Procedures and Techniques ..........................7-3 Normal Assisted Takeoff............................................7-4 Unassisted Takeoff.....................................................7-5 Crosswind Takeoff .....................................................7-5 Assisted ...................................................................7-5 Unassisted...............................................................7-6 Aerotow Climb-Out ....................................................7-6 Aerotow Release.........................................................7-8 Slack Line ...................................................................7-9 Boxing the Wake ......................................................7-10 Ground Launch Takeoff Procedures ............................7-11 CG Hooks .................................................................7-11 Signals ......................................................................7-11 Prelaunch Signals (Winch/Automobile) ...............7-11 Inflight Signals ......................................................7-12 Tow Speeds ..............................................................7-12 Automobile Launch ..................................................7-14 Crosswind Takeoff and Climb .................................7-14 Normal Into-the-Wind Launch .................................7-15 Climb-Out and Release Procedures ..........................7-16 Self-Launch Takeoff Procedures ..............................7-17 Preparation and Engine Start ....................................7-17 Taxiing .....................................................................7-18 Pretakeoff Check ......................................................7-18 Normal Takeoff ........................................................7-19 Crosswind Takeoff ...................................................7-19 Climb-Out and Shutdown Procedures ......................7-19 Landing .....................................................................7-21 Gliderport/Airport Traffic Patterns and Operations .....7-22 Normal Approach and Landing ................................7-22 Crosswind Landing ..................................................7-25 Slips ..........................................................................7-25 Downwind Landing ..................................................7-27 After Landing and Securing .....................................7-27viiiPerformance Maneuvers ..............................................7-27 Straight Glides ..........................................................7-27 Turns.........................................................................7-28 Roll-In ...................................................................7-29 Roll-Out ................................................................7-30 Steep Turns ...........................................................7-31 Maneuvering at Minimum Controllable Airspeed ...7-31 Stall Recognition and Recovery ...............................7-32 Secondary Stalls ....................................................7-34 Accelerated Stalls .................................................7-34 Crossed-Control Stalls ..........................................7-35 Operating Airspeeds .....................................................7-36 Minimum Sink Airspeed ..........................................7-36 Best Glide Airspeed..................................................7-37 Speed to Fly ..............................................................7-37 Chapter 8Abnormal and Emergency Procedures .............8-1 Introduction....................................................................8-1 Porpoising ......................................................................8-2 Pilot-Induced Oscillations (PIOs) ..............................8-2 PIOs During Launch ...................................................8-2 Factors Influencing PIOs ........................................8-2 Improper Elevator Trim Setting ..............................8-3 Improper Wing Flaps Setting ..................................8-3 Pilot-Induced Roll Oscillations During Launch .........8-3 Pilot-Induced Yaw Oscillations During Launch ........8-4 Gust-Induced Oscillations ..............................................8-5 Vertical Gusts During High-Speed Cruise .................8-5 Pilot-Induced Pitch Oscillations During Landing ......8-6 Glider-Induced Oscillations ...........................................8-6 Pitch Influence of the Glider Towhook Position ........8-6 Self-Launching Glider Oscillations During Powered Flight ...........................................................8-7 Nosewheel Glider Oscillations During Launchesand Landings ..............................................................8-7 Tailwheel/Tailskid Equipped Glider Oscillations During Launches and Landings ..................................8-8 Aerotow Abnormal and Emergency Procedures ............8-8 Abnormal Procedures .................................................8-8 Towing Failures........................................................8-10 Tow Failure With Runway To Land and Stop ......8-11 Tow Failure Without Runway To Land BelowReturning Altitude ................................................8-11 Tow Failure Above Return to Runway Altitude ...8-11 Tow Failure Above 800' AGL ..............................8-12 Tow Failure Above Traffic Pattern Altitude .........8-13 Slack Line .................................................................8-13 Ground Launch Abnormal and Emergency Procedures ....................................................................8-14 Abnormal Procedures ...............................................8-14 Emergency Procedures .............................................8-14 Self-Launch Takeoff Emergency Procedures ..............8-15 Emergency Procedures .............................................8-15 Spiral Dives ..................................................................8-15 Spins .............................................................................8-15 Entry Phase ...............................................................8-17 Incipient Phase .........................................................8-17 Developed Phase ......................................................8-17 Recovery Phase ........................................................8-17 Off-Field Landing Procedures .....................................8-18 Afterlanding Off Field .............................................8-20 Off-Field Landing Without Injury ........................8-20 Off-Field Landing With Injury .............................8-20 System and Equipment Malfunctions ..........................8-20 Flight Instrument Malfunctions ................................8-20 Airspeed Indicator Malfunctions ..........................8-21 Altimeter Malfunctions .........................................8-21 Variometer Malfunctions ......................................8-21 Compass Malfunctions .........................................8-21 Glider Canopy Malfunctions ....................................8-21 Broken Glider Canopy ..........................................8-22 Frosted Glider Canopy ..........................................8-22 Water Ballast Malfunctions ......................................8-22 Retractable Landing Gear Malfunctions ..................8-22 Primary Flight Control Systems ...............................8-22 Elevator Malfunctions ..........................................8-22 Aileron Malfunctions ............................................8-23 Rudder Malfunctions ............................................8-24 Secondary Flight Controls Systems .........................8-24 Elevator Trim Malfunctions .................................8-24 Spoiler/Dive Brake Malfunctions .........................8-24 Miscellaneous Flight System Malfunctions .................8-25 Towhook Malfunctions ............................................8-25 Oxygen System Malfunctions ..................................8-25 Drogue Chute Malfunctions .....................................8-25 Self-Launching Gliders ................................................8-26 Self-Launching/Sustainer Glider Engine Failure During Takeoff or Climb ..........................................8-26 Inability to Restart a Self-Launching/SustainerGlider Engine While Airborne .................................8-27 Self-Launching Glider Propeller Malfunctions ........8-27 Self-Launching Glider Electrical System Malfunctions .............................................................8-27 In-flight Fire .............................................................8-28 Emergency Equipment and Survival Gear ...................8-28 Survival Gear Checklists ..........................................8-28 Food and Water ........................................................8-28ixClothing ....................................................................8-28 Communication ........................................................8-29 Navigation Equipment ..............................................8-29 Medical Equipment ..................................................8-29 Stowage ....................................................................8-30 Parachute ..................................................................8-30 Oxygen System Malfunctions ..................................8-30 Accident Prevention .....................................................8-30 Chapter 9Soaring Weather ..................................................9-1 Introduction....................................................................9-1 The Atmosphere .............................................................9-2 Composition ...............................................................9-2 Properties ....................................................................9-2 Temperature............................................................9-2 Density ....................................................................9-2 Pressure ...................................................................9-2 Standard Atmosphere .................................................9-3 Layers of the Atmosphere ..........................................9-4 Scale of Weather Events ................................................9-4 Thermal Soaring Weather ..............................................9-6 Thermal Shape and Structure .....................................9-6 Atmospheric Stability .................................................9-7 Air Masses Conducive to Thermal Soaring ...................9-9 Cloud Streets ..............................................................9-9 Thermal Waves...........................................................9-9 Thunderstorms..........................................................9-10 Lifted Index ..........................................................9-12 K-Index .................................................................9-12 Weather for Slope Soaring .......................................9-14 Mechanism for Wave Formation ..............................9-16 Lift Due to Convergence ..........................................9-19 Obtaining Weather Information ...................................9-21 Preflight Weather Briefing........................................9-21 Weather-ReIated Information ..................................9-21 Interpreting Weather Charts, Reports, andForecasts ......................................................................9-23 Graphic Weather Charts ...........................................9-23 Winds and Temperatures Aloft Forecast ..............9-23 Composite Moisture Stability Chart .....................9-24 Chapter 10Soaring Techniques ..........................................10-1 Introduction..................................................................10-1 Thermal Soaring ...........................................................10-2 Locating Thermals ....................................................10-2 Cumulus Clouds ...................................................10-2 Other Indicators of Thermals ................................10-3 Wind .....................................................................10-4 The Big Picture .....................................................10-5Entering a Thermal ..............................................10-5 Inside a Thermal.......................................................10-6 Bank Angle ...........................................................10-6 Speed .....................................................................10-6 Centering ...............................................................10-7 Collision Avoidance ................................................10-9 Exiting a Thermal .....................................................10-9 Atypical Thermals ..................................................10-10 Ridge/Slope Soaring ..................................................10-10 Traps ......................................................................10-10 Procedures for Safe Flying .....................................10-12 Bowls and Spurs .....................................................10-13 Slope Lift ................................................................10-13 Obstructions ...........................................................10-14 Tips and Techniques ...............................................10-15 Wave Soaring .............................................................10-16 Preflight Preparation ...............................................10-17 Getting Into the Wave ............................................10-18 Flying in the Wave .................................................10-20 Soaring Convergence Zones ...................................10-23 Combined Sources of Updrafts ..............................10-24 Chapter 11Cross-Country Soaring .....................................11-1 Introduction..................................................................11-1 Flight Preparation and Planning ...................................11-2 Personal and Special Equipment ..................................11-3 Navigation ....................................................................11-5 Using the Plotter .......................................................11-5 A Sample Cross-Country Flight ...............................11-5 Navigation Using GPS .............................................11-8 Cross-Country Techniques ...........................................11-9 Soaring Faster and Farther .........................................11-11 Height Bands ..........................................................11-11 Tips and Techniques ...............................................11-12 Special Situations .......................................................11-14 Course Deviations ..................................................11-14 Lost Procedures ......................................................11-14 Cross-Country Flight in a Self-Launching Glider .....11-15 High-Performance Glider Operations and Considerations ............................................................11-16 Glider Complexity ..................................................11-16 Water Ballast ..........................................................11-17 Cross-Country Flight Using Other Lift Sources ........11-17 Chapter 12Towing ................................................................12-1 Introduction..................................................................12-1 Equipment Inspections and Operational Checks .........12-2 Tow Hook ................................................................12-2 Schweizer Tow Hook ...........................................12-2x。

基于ARM7的无人直升机硬件系统设计

13942009,30(6)计算机工程与设计Computer Engineering and Design0引言飞行机器人是一个极具挑战性的多学科交叉的前沿性研究课题。

作为空中机器人的无人驾驶直升飞机，在军事上可用于侦察、监视等，在民用上可用于大地测量、遥感等。

无人直升机在飞行过程中环境恶劣，因此对机载电子设备提出了很高的要求，特别是机载电子设备的可靠性和稳定性。

无人直升的机飞行控制系统要求具有高性能的自主导航、自动飞行控制、任务管理和手自控切换的综合系统，需要进行大量复杂的数据处理与数学运算。

鉴于无人直升机在失控时可能对人的安全构成威胁，要求我们从可靠性的稳定性出发整合硬件系统，特别是手动控制时的可靠性。

1总体构架飞行控制系统是由飞行控制计算机、传感器系统、GPS 、机载伺服系统、地面检测系统及电源组成。

控制器的核心是主控制模块，该模块的功能和接口决定了飞控计算机的性能。

在我们实验室原来的飞行控制系统，是以PC104为导航控制核心，以RT-Linux 为嵌入式实时控制系统。

PC104的运算能力是十分强大的，但是它的体积过大，并且有许多无用的接口，这造成了极大的浪费。

在新的系统中，我们将基于ARM7自主设计飞行控制系统。

传感器系统由惯性测量元件(IMU )、电子罗盘(COMPASS )和声纳(SONAR )组成。

伺服控制系统由滚转、俯仰、航向、油门和总矩这5个舵机组成。

2硬件平台设计2.1飞行控制计算机飞行控制计算机板卡上主要包括：AT91SAM7SE (512)、MEGA8单片机各一片，ADM3202两片、MAX232一片以及ALVC164245一片。

飞行控制计算机板卡见系统框图(如图1所示)中的虚线框部分。

其中AT91SAM7SE (512)是计算机核心部分，它主要负责导航计算和飞行控制计算等；MEGA8主要负责从PCM1024Z 接收机上采样解码遥控器的控制信号，在手动模式收稿日期：2008-04-09E-mail ：jerryliau@嵌入式系统工程刘栋炼，裴海龙：基于ARM7的无人直升机硬件系统设计2009,30(6)1395下控制无人直升机；ADM3202和MAX232是串口电平转换芯片，ADM3202是3.3V 电平到RS232电平，MAX232是5V 电平到RS232电平；ALVC164245是负责3.3V 与5V 的电平转换的，因为IMU 、电子罗盘及声纳的电平是5V 规范的，因此需要转换。

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stability criterion, see Figure 7.1. Common criteria are the maximum values of the sensitivity functions, i.e. Ms = max S(iω ) ,
ω
Mt = max T (iω )
ω
Recall that the number 1/ Ms is the shortest distance of the Nyquist curve of the loop transfer function to the critical point, see Figure 7.1. Also recall that the closed loop system will remain stable for process perturbations ∆ P provided that ∆ P(iω ) 1 ≤ , P(iω ) T (iω ) see Section 5.5. The largest value Mt of the complementary sensitivity function T is therefore a simple measure of robustness to process variations. Typical values of the maximum sensitivities are in the range of 1 to 2. Values close to one are more conservative and values close to 2 correspond to more aggressive controllers.
Gain and Phase Margins
The gain margin m and the phase margin ϕ m are classical stability criteria. Although they can be replaced by the maximum sensitivities it is useful to know about them because they are still often used practically. 253
7.2 Stability and Robustness to Process Variations
Stability and robustness to process uncertainties can be expressed in terms of the loop transfer function L = PC , the sensitivity function and the complementary sensitivity function S= 1 1 = , 1 + PC 1+ L T= PC L = . 1 + PC 1+ L
7.2
Stability and Robustness to Process Variations
Figure 7.1 Nyquist curve of the loop transfer function L with indication of gain, phase and stability margins.
From _Control System Design_ by Karl Johan Åström, 2002
7
Speciﬁcations
Copyright 2002, Karl Johan Åström. All rights reserved. Do not duplicate or redistribute.
7.1 Introduction
In this chapter we will discuss how the properties of a control system can be speciﬁed. This is important for control design because it gives the goals. It is also important for users of control so that they know how to specify, evaluate and test a system so that they know it will have the desired properties. Speciﬁcations on a control systems typically include: stability of the closed loopห้องสมุดไป่ตู้system, robustness to model uncertainty, attenuation of measurement noise, injection of measurement noise, and ability to follow reference signals. From the results of Chapter 5 it follows that these properties are captured by six transfer functions called the Gang of Six. The speciﬁcations can be expressed in terms of these transfer functions. Essential features of the transfer functions can be expressed in terms of their poles and zeros or features of time and frequency responses.
Since both S and T are functions of the loop transfer function speciﬁcations on the sensitivities can also be expressed in terms of speciﬁcations on the loop transfer function L. Many of the criteria are based on Nyquist’s 252
ϕ m = π + arg L(iω c )
(7.2)
The margins have simple geometric interpretations in the Nyquist diagram of the loop transfer function as is shown in Figure 7.1. Notice that an increase of controller gain simply expands the Nyquist curve radially. An increase of the phase of the controller twists the Nyquist curve clockwise, see Figure 7.1. Reasonable values of the margins are phase margin ϕ m = 30○ − 60○ , gain margin m = 2 − 5. Since it is necessary to specify both margins to have a guarantee of a reasonable robustness the margins m and ϕ m can be replaced by a single stability margin, deﬁned as the shortest distance of the Nyquist curve to the critical point −1, this distance is the inverse of the maximum sensitivity Ms . It follows from Figure 7.1 that both the gain margin and the phase margin must be speciﬁed in order to ensure that the Nyquist curve is far from the critical point. It is possible to have a system with a good gain margin and a poor phase margin and vice versa. It is also possible to have a system with good gain and phase margins which has a poor stability margin. The Nyquist curve of the loop transfer function of such a system is shown in Figure 7.2. This system has inﬁnite gain margin, a phase margin of 70○ which looks very reassuring, but the maximum sensitivity is Ms = 3.7 which is much too high. Since it is necessary to specify both the gain margin and the phase margin to endure robustness of a system it is advantageous to replace them by a single number. A simple analysis of the Nyquist curve shows that the following inequalities hold.