民航导航系统原理与应用

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1、2022/12/15(c)Shau-Shiun Jan,IAA,NCKU1民航導航系統原理與應用成大民航研究所詹劭勳 老師2022/12/15(c)Shau-Shiun Jan,IAA,NCKU2Course Information Books Avionics Navigation Systems,M.Kayton,W.R.Fried,John,ISBN:0471547956 Many reference books(Keywords:GPS,INS):Global Positioning System(GPS):Signals,Measurements and Performance,P.

2、Misra and P.Enge,Ganga-Jamuna,2001 Strapdown Inertial Navigation Systems,D.H.Titterton and J.L.Weston The Global Positioning System and Inertial Navigation,Farrell and Barth,McGraw-Hill,1999 Integrated Aircraft Navigation,J.L.Farrell,Academic Press,1976 Global Positioning Systems,Inertial Navigation

3、 and Integration,Grewal,Weill and Andrews,Wiley Interscience,20012022/12/15(c)Shau-Shiun Jan,IAA,NCKU3Outline Part 1:Introduction Part 2:Navigation Coordinate Part 3:Radio Navigation Systems Part 4:Global Positioning System Part 5:Augmentation Systems2022/12/15(c)Shau-Shiun Jan,IAA,NCKU4Part 1:Intro

4、duction An Overview of Navigation and Guidance2022/12/15(c)Shau-Shiun Jan,IAA,NCKU5Navigation and Guidance Navigation:The process of determining a vehicles/persons/objects position Guidance:The process of directing a vehicle/person/object from one point to another along some desired path2022/12/15(c

5、)Shau-Shiun Jan,IAA,NCKU6Example Getting from AA building to Tainan Train Station How would you tell someone how to get there?How would you tell a robot to get there?Both problems assume there is some agreed upon coordinate system.Latitude,Longitude,Altitude(Geodetic)North,East,Down with respect to

6、some origin Ad Hoc system(“starting from AA building you go 1 block”)Most of our work in this class is going to be with the Navigation problem2022/12/15(c)Shau-Shiun Jan,IAA,NCKU7Applications Air Transportation Marine,Space,and Ground Vehicles Personal Navigation/Indoor Navigation Surveying2022/12/1

7、5(c)Shau-Shiun Jan,IAA,NCKU8A Navigation or Guidance System Steering commands:instructions on what to do to get the vehicle going to where it should be going Turn right/left Go up/down Speed up/slow downSensor#1:Sensor#2Sensor#NNavigation and/orGuidanceProcessorSteering commandsNavigation state vect

8、or2022/12/15(c)Shau-Shiun Jan,IAA,NCKU9Navigation State/State Vector A set of parameters describing the position,velocity,altitude of a vehicle Navigation state vector:Position=3 coordinates of location,a 3x1 vector Velocity=derivative of the position vector,a 3x1 vector Attitude=a set of parameters

9、 which describe the vehicles orientation in space2022/12/15(c)Shau-Shiun Jan,IAA,NCKU10Position and Velocity More often than not,we are interested in position and velocity vectors expressed in separate coordinates(more on this later)()()()Position vector expressed in some coordinate system AVelocity

10、 vector expressed in coordinate system A,speedAAAAAPVdPVVdt2022/12/15(c)Shau-Shiun Jan,IAA,NCKU11Attitude We will deal with two ways of describing the orientation of two coordinate frames Euler angles:3 angles describing relationship between 2-coordinate systems Transformation matrix:maps vector in“

11、A”coordinate frame to“B”1 11 21 32 12 22 33 13 23 3E u le r A n g le s T ra n sfo rm a tio n M a trix c c cc c cc c c 2022/12/15(c)Shau-Shiun Jan,IAA,NCKU12Attitude(continued)The first entry of the attitude“vector”,is called yaw or heading.111213212223313233Euler Angles Transformation Matrix ccccccc

12、cc2022/12/15(c)Shau-Shiun Jan,IAA,NCKU13Navigation and Guidance Systems In this class we will look at ways to determining some or all of the components of the navigation state vector.Some navigation systems provide all of the entries of the navigation state vector(inertial navigation systems)and som

13、e only provide a subset of the state vector.Guidance systems give instructions on how to achieve the desired position.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU14Navigation and Guidance Systems2022/12/15(c)Shau-Shiun Jan,IAA,NCKU15Categories of Navigation Dead Reckoning Positioning(position fixing)Navigat

14、ion systems are either one of the two or are hybrids.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU16Dead Reckoning Systems“Extrapolation”system:position is derived from a“series”of velocity,heading,acceleration or rotation measurements relative to an initial position.To determine current position you must kn

15、ow history of past position Heading and speed or velocity systems Inertial navigation systems System accuracy is a function of vehicle position trajectory2022/12/15(c)Shau-Shiun Jan,IAA,NCKU17Positioning/Position Fixing Systems Determine position from a set of measurements.Knowledge of past position

16、 history is not required Mapping system Pilotage(pp.504-505)Celestial systems Star Trackers Radio systems VOR,DME,ILS,LORAN Satellite systems GPS,GLONASS,Galileo System accuracy is independent of vehicle position trajectory2022/12/15(c)Shau-Shiun Jan,IAA,NCKU18Brief History of Navigation Land Naviga

17、tion “pilotage”traveling by reference to land marks.Marine Navigation Greeks(300350 B.C.)Record of going far north as Norway,“Periodic Scylax”(Navigation manual).Vikings(1000 A.D.)had compass Ferdinand Magellan(1519)recorded use of charts(maps),devices for getting star fixes,compass,hour glass and l

18、og(for speed).The important point to note is that these early navigators were using dead reckoning and position fixing(hybrid system)2022/12/15(c)Shau-Shiun Jan,IAA,NCKU19Determine Your Latitude Law of sinessin2sin2-sin2-cossin2-cosEEhRsRh PolarisEquators=LatitudehsRE2022/12/15(c)Shau-Shiun Jan,IAA,

19、NCKU20How do you determine longitude?Dead reckoning Compass for heading,log for speed Not very accurate,heading errors,speed errors position errors Errors grow with time2022/12/15(c)Shau-Shiun Jan,IAA,NCKU21The Longitude Problem Longitude act of 1714 20,000 for 1/2o solution 15,000 for 2/3o solution

20、 10,000 for 1o solution(about 111km resolution at equator!)Board of longitude Halley(“Halley Comet”)Newton Solution turned out to be a stable watch/clock 2022/12/15(c)Shau-Shiun Jan,IAA,NCKU2220th Century and Aviation Position fixing(guidance)systems:Pilotage Fires(1920)US mail routes Radio beacons

21、Late 1940s most of the systems we use today started entering services By 1960s VOR/DME and ILS become standard in commercial aviation Dead reckoning Inertial navigation(1940)German v-2 Rocket Nuclear submarine(US NAVY)Oceanic commercial flight2022/12/15(c)Shau-Shiun Jan,IAA,NCKU2320th Century and Av

22、iation Satellite based navigation systems US NAVY Transit System(1964)Global Positioning System 1978 first satellite launched 1995 declared operational Other satellite navigation systems GLONASS Former Soviet Union Galileo being developed by the EU2022/12/15(c)Shau-Shiun Jan,IAA,NCKU24Performance Me

23、trics and Trade-Off1.Cost2.Autonomy3.Coverage4.Capacity5.Accuracy6.Availability7.Continuity8.IntegrityArea of active research:5,6,7,8Accuracy:we will visit it in detail later on.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU25Part 2:Navigation Coordinate Frames,Transformations and Geometry of Earth.Navigation

24、 coordinate frames Geometry of earth2022/12/15(c)Shau-Shiun Jan,IAA,NCKU26Coordinate Frames The position vector(the main output of any navigation system and our primary concern in this class)can be expressed in various coordinate frames.Notation denotes a vector denotes the coordinate frameAPA2022/1

25、2/15(c)Shau-Shiun Jan,IAA,NCKU27Why Multiple Coordinate Frames?Depending on the application at hand some coordinates can be easier to use.In some applications,multiple frames are used simultaneously because different parts of the problem are easier to manage.For example,GPS:normally position and vel

26、ocity in“ECEF”INS:normally position in geodetic and velocity in“NED”2022/12/15(c)Shau-Shiun Jan,IAA,NCKU28Coordinate Frames Cartesian ECEF ECI NED(locally tangent Frames)ENU(locally tangent Frames)Spherical/cylindrical Geodetic Azimuth-Elevation-Range Bearing-Range-AttitudeExcept for ECI,all are non

27、-inertial frames,an inertial frames is a non-accelerating(translation and rotation)coordinate frames.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU29ECEF and ECI Earth Centered and Earth Fixed(ECEF)Cartesian Frame with origin at the center of earth.Fixed to and rotates with earth.A non-inertial frame.Earth Ce

28、ntered Inertial(ECI)Cartesian frame with origin at earths center.Z axis along earths rotation vector.X-y plane in equatorial plane.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU30Geodetic Geodetic(Latitude,Longitude,Altitude)Spherical Latitude()=north south of equator,range 90o Longitude()=east west of prime

29、meridian,range 180o Altitude(h)=height above reference datum“+”north latitude,east longitude,down(below)datum altitudeearth rotation vector360 24360365*2415.041/ehr 2022/12/15(c)Shau-Shiun Jan,IAA,NCKU31NED and ENU North-East-Down(NED)Cartesian No fixed location for the origin Locally tangent to ear

30、th at origin East-North-Up(ENU)Cartesian Similar to NED except for the direction of 1-2-3 axes.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU32Azimuth-Elevation-Range Azimuth-Elevation-Range Spherical No fixed origin Azimuth is angle between a line connecting the origin and the point of interest(in the tangen

31、t plane)and a line from origin to north pole Elevation is the angle between the local tangent plane and a line connecting the origin to a point of interest Range is the slant or line-of-sight distance Azimuth-headingElevationRange 2022/12/15(c)Shau-Shiun Jan,IAA,NCKU33Azimuth-Elevation-Range Two typ

32、es of azimuth or heading angles True:measured with respect to the geographic(true)north pole(T)Magnetic:measured with respect to the magnetic north pole(M)Azimuth-headingElevationRange magnetic variationdeclenationTM2022/12/15(c)Shau-Shiun Jan,IAA,NCKU34Earth Magnetic Field 1st order approximation i

33、s that of a simple dipole Poles move with time.In 1996 magnetic north pole was located at(79oN,105oW)In 2003 it is located at(82oN,112oW)Also,can“wander”by as much as 80km per day2022/12/15(c)Shau-Shiun Jan,IAA,NCKU35Earth Magnetic Field Magnetic poles are used in navigation because M is easier to m

34、easure than T Bx and By are measured by devices called magnetometers(Ch.9)Anomalies such as local iron deposits lead to erroneous M reading Iron range deposits of N.E.Minnesota can lead to errors as large as 50o 1tanyMxBB2022/12/15(c)Shau-Shiun Jan,IAA,NCKU36Shape/Geometry of Earth1.Topographical/ph

35、ysical surface2.Geoid3.Reference ellipsoid2022/12/15(c)Shau-Shiun Jan,IAA,NCKU37Shape/Geometry of Earth(continued)Topographical surface shape assumed by earths crust.Complicated and difficult to model mathematically.Geoid an equipotential surface of earths gravity field which best fits(least squares

36、 sense)global mean sea level(MSL)Reference ellipsoid mathematical fit to the geoid that is an ellipsoid of revolution and minimizes the mean-square deviation of local gravity(i.e.,local norm to geoid)and ellipsoid norm,WGS-842022/12/15(c)Shau-Shiun Jan,IAA,NCKU38Latitude2022/12/15(c)Shau-Shiun Jan,I

37、AA,NCKU39WGS84 Four defining parameters Other parameters are derived from the four Equatorial radius=6378.137km Flattening=1/298.257223563 Rotation rate of earth in inertial space=15.041067 degree/hour Earths gravitational constant(GM)=3.986004x108m3/s22022/12/15(c)Shau-Shiun Jan,IAA,NCKU40Part3:Rad

38、io Navigation Systems I:FundamentalsI:FundamentalsII:Survey of Current Systems2022/12/15(c)Shau-Shiun Jan,IAA,NCKU41Radio Navigation Systems These are systems that use Radio Frequency(RF)signals to generate information required for navigation.C=speed of electromagnetic waves in free space(“speed of

39、light”)“Radio waves”correspond to electromagnetic waves with frequency between 10 KHz and 300 GHz 882.997925 10/3.0 10/Cm sm swave length of RF signal where is frequency(units of Hz)Cff2022/12/15(c)Shau-Shiun Jan,IAA,NCKU42FrequencyFrequenciesWavelength Very Low Frequency(VLF)10 kmLow Frequency(LF)3

40、0 300 KHz1 to 10 kmMedium Frequency(MF)300 KHz 3 MHz100 m to 1 kmHigh Frequency(HF)3 30 MHz10 to 100 mVery High Frequency(VHF)30 300 MHz1 to 10 mUltra High Frequancy(UHF)300 MHz 3 GHz10 cm to 1 mSuper High Frequency(SHF)3 30 GHz1 to 10 cm2022/12/15(c)Shau-Shiun Jan,IAA,NCKU43FrequencyVHFLFMFHFVHFUHF

41、SHFEHF0.1110100LSCKSLGPS signals are L band SignalsMLS uses C band signalsExpand2022/12/15(c)Shau-Shiun Jan,IAA,NCKU44Radio Signal Propagation(1/3)Ground Waves Waves below the HF range(i.e.,30 MHz 100 MHz 3 GHz predictable Above 3 GHz absorption Above 10 GHz discrete absorption2022/12/15(c)Shau-Shiu

42、n Jan,IAA,NCKU46Radio Signal Propagation(3/3)Sky Waves HF and below(i.e.,30 MHz)Multipath Fading Skip distance:depends of frequency and ionosphere conditions2022/12/15(c)Shau-Shiun Jan,IAA,NCKU47Modulation Techniques Modulation how you place information of the RF signal Amplitude modulation(AM)chang

43、e the amplitude of sinusoid to relay information Frequency modulation(FM)change in frequency of transmitted signal to relay information Phase modulation(PM)change phase of transmitted signal to relay information The signal can be transmitted as a pulse or a continuous wave.Either one can be modulate

44、d by the above methods.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU48How do you distinguish one beacon from another?Frequency division multiple access(FDMA)each transmitter/beacon uses a different frequency Time division multiple access(TDMA)each transmitter/beacon transmits at a specified timeCode division

45、 multiple access(CDMA)each transmitter/beacon uses an identifier code to distinguish itself from the other transmitters or beacons2022/12/15(c)Shau-Shiun Jan,IAA,NCKU49Important ConclusionsLow frequency systems ground wave transmission long range systems,Loran.High frequency systems line of sight sy

46、stemsPhysical QuantityNameSensor PropertiesDistance/RangeL.O.S.BearingL.O.S.tTDOAGround Wave2022/12/15(c)Shau-Shiun Jan,IAA,NCKU502022/12/15(c)Shau-Shiun Jan,IAA,NCKU51Phases of FlightTakeoffDeparture(Climb)En RouteApproach(Descent)Landing2022/12/15(c)Shau-Shiun Jan,IAA,NCKU52Phases of Flight Takeof

47、f Starts at takeoff roll and ends when climb is established.Departure Ends when the aircraft has left the so called terminal area.En Route Majority of a flight is spent in this phase.Ends when the approach phase begins.Navigation error during this phase must be less than 2.8 N.M(2-)over land and 12

48、N.M over oceans.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU53En RouteNAV beacon(NAVAID)DestinationRandom or area navigationDeparture2022/12/15(c)Shau-Shiun Jan,IAA,NCKU54Phases of Flight Approach Ends when the runway is in sight.The minimum descent altitude or decision height is reached.(MDA or DH)Landing

49、Begins at the MDA or DH and ends when the aircraft leaves the runway.MDA or DHCeiling heightClouds,Fog,or Haze2022/12/15(c)Shau-Shiun Jan,IAA,NCKU55Accuracy Requirement Accuracy required during the approach and landing phases of flight depend on the type of operation being conducted.Phase of FlightN

50、avigation/Guidance SystemTakeoff Visual,Radar*DepartureVOR,DME,Radar*En RouteVOR,DME,Radar*Approach and LandingVOR,DME,Radar*,ILS,MLS*Used by the ground based controllers to give the user“steering“directions and to ensure traffic separation between aircraft.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU56VORV

51、OR(VHF Omni-Directional Range)Provides bearing information Uses VHF radio signals FDMA with frequencies between 112 and 117.95 MHZ Bearing accuracy 1o to 3o Works by comparing the phase of 2 sinusoids.One has bearing dependent phase the other doesnt.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU57DMEDME(Dista

52、nce Measuring Equipment):Measures slant range Operates between 962 1213 MHzAccuracy 0.1 to 0.17 n.m.(nominal)(185 315 m)Principle of operation1.Airborne unit sends a pair of pulses2.Ground based beacon(transponder)picks up the signal3.After a 50sec delay,transponder replies4.Airborne unit receives p

53、ulse pair and computes range by:0.5(50 sec)CT2022/12/15(c)Shau-Shiun Jan,IAA,NCKU58DME How does a particular user distinguish their pulse from that of other users?Normally,VOR and DME are collocated,in the U.S.there are 1000 VOR/DME beacons.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU59ILSILS(Instrument Lan

54、ding System):System provides angular information Used exclusively for approach and landing2022/12/15(c)Shau-Shiun Jan,IAA,NCKU60ILS It provides information about deviation from the center line()and guide slope()Includes marker beacons that are installed at discrete distances from the runway.Outer Ma

55、rker(OM)4 to 7 n.m.from runway Middle Marker(MM)-3500 ft from runway Inner Marker(IM)-1000 ft from runway2022/12/15(c)Shau-Shiun Jan,IAA,NCKU61Decision Height(DH)Height above the runway at which landing must be aborted if the runway is not in sight.Based on DH,three categories of landing are availab

56、le:CAT IDH 200 ft2600 ft visibilityCAT IIDH 100 ft1200 ft visibilityCAT IIIIIIA:DH 100 ft700 ft visibilityIIIB:DH 50 ft150 ft visibility2022/12/15(c)Shau-Shiun Jan,IAA,NCKU62MLSMLS(Microwave Landing System):Designed to“Look”like an ILS but mitigate the weaknesses of ILS.Operates between 5.0 5.2 GHz

57、Scanning beam used to provide both lateral(localizer equivalent)and vertical(glide slope)information.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU63LORANLORAN(LOng RAnge Navigation):Hyperbolic position fixing system.Operates at 90 to 100 KHz.Area navigation capable.(i.e.,not a guidance system only)Consists o

58、f chains:1 master and multiple secondary stations.Master station sends a signal.After a short(known)delay,the secondary stations“fire”in sequence.Accuracy 0.25 n.m.(463 m)2022/12/15(c)Shau-Shiun Jan,IAA,NCKU64Part4:Global Positioning System2022/12/15(c)Shau-Shiun Jan,IAA,NCKU65Satellite Navigation S

59、ystems Sputnik I(1957)Beginning of the space age A ground station at a known location can determine the satellites orbit from a record of Doppler shift.US Navys Transit Applied Physics Lab(Johns Hopkins Univ.)Initial concept in 1958.Fully operational in 1964.Used by submarine fleet.Later use by civi

60、lians.Decommissioned in 1996.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU66Satellite Navigation Systems US Navy and Air Force programs combined to become GPS Basic architecture approved in 1973 1st satellite launch in 1978 Fully operational in 1995(23 years!)Other satellite navigation systems GLONASS(Russia

61、),Galileo(EU),Beiduo(China)Called Global Navigation Satellite System(GNSS)2022/12/15(c)Shau-Shiun Jan,IAA,NCKU67GPS System Objectives To provide the U.S.military with accurate estimates of position,velocity,and time(PVT).Position accuracy within 10 m,velocity accuracy within 0.1 m/s,and time accurac

62、y within 100 nsec.2-levels of service:Standard positioning service(SPS)For peaceful civilian use.Precise positioning service(PPS)For DoD(Department of Defense)authorized users(military).Selective availability(SA)clock dither Antispoofing(AS)encryption 2022/12/15(c)Shau-Shiun Jan,IAA,NCKU68System Des

63、ign Considerations Active or passive?GPS is passive Position fixing method Doppler,hyperbolic,multilateration.GPS uses multilateration.Pulsed vs.continuous wave(CW)signal CDMA on same frequency(spread spectrum)L1=1575.42 MHz L2=1227.60 MHz L3,L4 classified payloads on satellites L5=1176.45 MHz,new c

64、ivil frequency,not here yet2022/12/15(c)Shau-Shiun Jan,IAA,NCKU69System Design Considerations Carrier frequency:L-band.Ionospheric defraction less at higher frequencies but power loss is greater.Constellation LEO,MEO,or GEO?LEO 1020 minutes visibility time per SV,100 200 SVs required.(cheap)MEO Visi

65、ble for several hours per pass.Launch more expensive than LEO.GEO Poor coverage at higher latitudes.Global coverage with few SVs.Expensive to launch.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU70System Design Considerations GPS uses a MEO constellation.1st SV launched in 1978.Development of system estimated

66、 to be$10 billion.Annual operation and maintenance cost estimated at$500 Million.Technologies that were key to the development of GPS were:Stable space platforms in predictable orbits.Ultrastable clocks.Spread spectrum signaling.Integrated circuits.2022/12/15(c)Shau-Shiun Jan,IAA,NCKU71System Architecture2022/12/15(c)Shau-Shiun Jan,IAA,NCKU72Space Segment 24+satellites 6 orbital planes 55 degree inclination 12 hour orbits 4 SVs per plane 26561 Km from earths center 2.7 Km/sec2022/12/15(c)Shau-Sh