民航导航系统原理与应用.ppt

2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,1,民航導航系統原理與應用,成大民航研究所 詹劭勳 老師,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,2,Course 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. 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 and Integration, Grewal, Weill and Andrews, Wiley Interscience, 2001,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,3,Outline,Part 1: Introduction Part 2: Navigation Coordinate Part 3: Radio Navigation Systems Part 4: Global Positioning System Part 5: Augmentation Systems,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,4,Part 1: Introduction An Overview of Navigation and Guidance,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,5,Navigation 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 path,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,6,Example,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 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 problem,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,7,Applications,Air Transportation Marine, Space, and Ground Vehicles Personal Navigation / Indoor Navigation Surveying,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,8,A 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 down,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,9,Navigation 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 which describe the vehicles orientation in space,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,10,Position and Velocity,More often than not, we are interested in position and velocity vectors expressed in separate coordinates (more on this later),2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,11,Attitude,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 “A” coordinate frame to “B”,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,12,Attitude (continued),The first entry of the attitude “vector”, , is called yaw or heading.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,13,Navigation 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 some only provide a subset of the state vector. Guidance systems give instructions on how to achieve the desired position.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,14,Navigation and Guidance Systems,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,15,Categories of Navigation,Dead Reckoning Positioning (position fixing) Navigation systems are either one of the two or are hybrids.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,16,Dead 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 know history of past position Heading and speed or velocity systems Inertial navigation systems System accuracy is a function of vehicle position trajectory,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,17,Positioning / Position Fixing Systems,Determine position from a set of measurements. Knowledge of past position 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 trajectory,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,18,Brief History of Navigation,Land Navigation “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 log (for speed). The important point to note is that these early navigators were using dead reckoning and position fixing (hybrid system),2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,19,Determine Your Latitude,Polaris,Equators,=Latitude,h,s,RE,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,20,How do you determine longitude?,Dead reckoning Compass for heading, log for speed Not very accurate, heading errors, speed errors position errors Errors grow with time,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,21,The Longitude Problem,Longitude act of 1714 20,000 for 1/2o solution 15,000 for 2/3o solution 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,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,22,20th Century and Aviation,Position fixing (guidance) systems: Pilotage Fires (1920) US mail routes Radio beacons 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 flight,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,23,20th Century and Aviation,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 EU,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,24,Performance Metrics and Trade-Off,Cost Autonomy Coverage Capacity Accuracy Availability Continuity Integrity Area of active research: 5,6,7,8 Accuracy: we will visit it in detail later on.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,25,Part 2: Navigation Coordinate Frames, Transformations and Geometry of Earth.,Navigation coordinate frames Geometry of earth,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,26,Coordinate 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,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,27,Why 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 velocity in “ECEF” INS: normally position in geodetic and velocity in “NED”,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,28,Coordinate Frames,Cartesian ECEF ECI NED (locally tangent Frames) ENU (locally tangent Frames),Spherical/cylindrical Geodetic Azimuth-Elevation-Range Bearing-Range-Attitude,Except for ECI, all are non-inertial frames, an inertial frames is a non-accelerating (translation and rotation) coordinate frames.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,29,ECEF 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 Centered Inertial (ECI) Cartesian frame with origin at earths center. Z axis along earths rotation vector. X-y plane in equatorial plane.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,30,Geodetic,Geodetic (Latitude, Longitude, Altitude) Spherical Latitude () = north south of equator, range 90o Longitude () = east west of prime meridian, range 180o Altitude (h) = height above reference datum “+” north latitude, east longitude, down (below) datum altitude,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,31,NED and ENU,North-East-Down (NED) Cartesian No fixed location for the origin Locally tangent to earth at origin East-North-Up (ENU) Cartesian Similar to NED except for the direction of 1-2-3 axes.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,32,Azimuth-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 tangent 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,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,33,Azimuth-Elevation-Range,Two types 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),2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,34,Earth Magnetic Field,1st order approximation is 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 day,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,35,Earth Magnetic Field,Magnetic poles are used in navigation because M is easier to measure 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,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,36,Shape / Geometry of Earth,Topographical / physical surface Geoid Reference ellipsoid,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,37,Shape / 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 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-84,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,38,Latitude,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,39,WGS84,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/s2,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,40,Part3:Radio Navigation Systems I: Fundamentals,I: Fundamentals II: Survey of Current Systems,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,41,Radio 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 light ”) “ Radio waves ” correspond to electromagnetic waves with frequency between 10 KHz and 300 GHz,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,42,Frequency,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,43,Frequency,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,44,Radio Signal Propagation (1/3),Ground Waves Waves below the HF range (i.e., 3 MHz) Unpredictable path characteristics Required large antenna Atmospheric noise,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,45,Radio Signal Propagation (2/3),Line of Sight Waves: Signals 30 MHz 100 MHz 3 GHz predictable Above 3 GHz absorption Above 10 GHz discrete absorption,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,46,Radio Signal Propagation (3/3),Sky Waves HF and below (i.e., 30 MHz) Multipath Fading Skip distance: depends of frequency and ionosphere conditions,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,47,Modulation Techniques,Modulation how you place information of the RF signal Amplitude modulation (AM) change 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 modulated by the above methods.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,48,How 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 time Code division multiple access (CDMA) each transmitter/beacon uses an identifier code to distinguish itself from the other transmitters or beacons,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,49,Important Conclusions,Low frequency systems ground wave transmission long range systems, Loran. High frequency systems line of sight systems,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,50,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,51,Phases of Flight,Takeoff,Departure (Climb),En Route,Approach (Descent),Landing,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,52,Phases of Flight,Takeoff 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 N.M over oceans.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,53,En Route,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,54,Phases of Flight,Approach Ends when the runway is in sight. The minimum descent altitude or decision height is reached. (MDA or DH) Landing Begins at the MDA or DH and ends when the aircraft leaves the runway.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,55,Accuracy Requirement,Accuracy required during the approach and landing phases of flight depend on the type of operation being conducted.,*Used by the ground based controllers to give the user “steering“ directions and to ensure traffic separation between aircraft.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,56,VOR,VOR (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.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,57,DME,DME (Distance Measuring Equipment): Measures slant range Operates between 962 1213 MHz Accuracy 0.1 to 0.17 n.m. (nominal) (185 315 m) Principle of operation Airborne unit sends a pair of pulses Ground based beacon (transponder) picks up the signal After a 50sec delay, transponder replies Airborne unit receives pulse pair and computes range by :,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,58,DME,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.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,59,ILS,ILS (Instrument Landing System): System provides angular information Used exclusively for approach and landing,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,60,ILS,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 Marker (OM) 4 to 7 n.m. from runway Middle Marker (MM) - 3500 ft from runway Inner Marker (IM) - 1000 ft from runway,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,61,Decision 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 available:,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,62,MLS,MLS (Microwave Landing System): Designed to “Look” like an ILS but mitigate the weaknesses of ILS. Operates between 5.0 5.2 GHz Scanning beam used to provide both lateral (localizer equivalent) and vertical (glide slope) information.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,63,LORAN,LORAN (LOng RAnge Navigation): Hyperbolic position fixing system. Operates at 90 to 100 KHz. Area navigation capable. (i.e., not a guidance system only) Consists of 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),2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,64,Part4:Global Positioning System,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,65,Satellite Navigation Systems,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 civilians. Decommissioned in 1996.,2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,66,Satellite 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), Galileo (EU), Beiduo (China) Called Global Navigation Satellite System (GNSS),2019/7/17,(c)Shau-Shiun Jan, IAA, NCKU,67,GPS 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 accuracy within 100 nsec. 2-levels of service: Standard positioning service (SPS) For peaceful civilian use. Precise positioning service (PPS) For DoD (Department of Defense) authorize