CA2114482A1 - Infrared vehicle identification system - Google Patents

Abstract

Abstract of the Disclosure An infrared vehicle identification system comprising a microprocessor controlled infrared (IR) transmitter located on an aircraft nose wheel landing strut and an infrared receiver including a microprocessor enclosed in a plurality of edge light assemblies located along surface pathways of an airport including runways and taxiways. The infrared transmitter comprises an array of light emitting diodes (LEDs) arranged in a semicircle within the horizontal plane.
The transmitter emits a plurality of fields of encoded data to provide vehicle identification and position information.
One field comprises a steady stream of pulses that allows the IR receiver to calculate the baud rate of the transmitter and automatically adjust its internal timing.
The other fields include a unique word for marking the beginning of a message, the number of characters in the message, the vehicle identification number, the vehicle position and a checksum. The latter assures that a complete and correct message has been received. If the transmitted message is interrupted for any reason, the checksum will detect it and the messages will be voided. The IR receiver relays a valid message of vehicle identification and position to a central computer system at the airport control tower via the edge light assembly power wiring.

Description

~s ~

2 ~ g 2 IlaFRa~:D ~ICI~3 Il)E~TIFICATIO~il SYSTEll Back~lround of the Invention This invention relate~ to identification of airport surface traffic and in particular to an apparatus and method for detecting and identifying aircraft or other vehizle movement on airport taxiways, ru~ways and other surface axea~.
Currently, ground control of aircraft at an airport is done visually by the air traffic controller in the tower.
10 Low vi3ibili~y conditions ~ometLmes make it Lmpos~ible for the controller to see all parts of the field. Ground surface radar can help in providing coverage during low vi~ibility conditions; it play~ an important part in the solution of the runway incursion problem but cannot solve 15 the entire problem. A runway incursion i8 defined as "any occurrence at an airport involving an aircraft, vehicle, person, or ob~ect on the ground that create a collision hazard or r~sul~s in loss of separation with an aircraft taking off, intending to take off landing, or intending to 20 land." The U.S. Fed~ral ~dministration Ag0ncy (FAA) has e~kimated that it can only ju~tify the cost of ground surface radar at 29 4f the top lO0 airpor~s in the United Stat~s. However, ~uch radar only provides location information; it cannot alert the controller ~o pos~ible 25 conflicks be~ween aircraft.

In the prior art, an airport control and monitorinq system has been used to sense when an airplane reaches a certain point on a taxiway and controls switching lights on and off to indicate to the pilot when he may proceed on to a runway. 5uch a syskem ~ends microwave ~ensor information ~o a computer in the control tower. The compu~er comprises software for con~rolling ~he airport lighting and for pxoviding fault information on the airport lighting via display~ or a con~rol panel to an operator. Such a system is described in sales in~ormation provided on a Bi-directional Series 7 ~ransceiver (BRITEE) produced by ADB-ALNACO, Inc., A Siemens Company, of Columbus, Ohio~
However, such a sy~tem does not ~how the location of all vehicle~ on an airfield and i~ not able to detect and avoid a pos~ible vehicle incursion.
A well known approach to airport surface traffic control has been the use of scanning radars operating at high freguencie~ such as ~-band in order to obtain adequate definition and re.olution. ~n existing airport ground tra~fic control equipment of tha~ type is known in the art a~ Airport Surface Detection ~.quipment (ASDE). How~ver, 5uch equipment provids~ ~urv~illance only, no discrete identi~ication of aircraft on the ~urface being aYailable, A150 there i8 a ~eed for a rela~ively high an~enna tower and a relatively large rotation antenna system thereon.

Another approach to airport ground surveillance is a system described in U. S. Patent No. 3,872,474, issued March 18, 1374, to Arnold M. Levine and assigned to International Telephone and Telegraph Corporation, New York, NY, referred to as LOCAR (Lo~alized Cable Radar) which comprises a ~eries of small, lower powered, narrow pulses, transmitting radars ha~ing limi~ed range and time seguenced along opposite sides of a runway ramp or taxiway. In another U. S. Patent No.
4,197,536, issued on April 8, 1980, to Arnold M. ~evine, an airpor~c surface identification and control system is de~cribed for aircraft equipped with ATCRBS (Air Traffic Control Radio Beacon System) and ILS (Instrument Landing Sy~tem). However, these approaches are expensi~e, require sp~cial cabling and for identification pu~poses require expensive equipmsnt to be in~luded on the aircraft and other vehicles.
Another approach to vehicle identification such as types of aircraft by identifying the unique characteristic of the "footprintl~ presented ~y the configuration of wheels unique to a particular type of vehicle is des~ribed in U.S.
Patent ~o. 3,872,283, issued Narch 18, 1975, to Gerald ~.
Smith et al. and as~igned to The Cadre Corporation of A~lanta Georgia.
An automatic system for surveillance, guida~ce and fire-fighting at airpor~s using i~frared sen~ors is - ' -2 ~

described in U. SO ~atent No. 4,845,629, i.ssued July 4, 1989 to Maria Y. Z. Murga. The infrared sensors are arranged along the flight lanes and their output signals are processed by a computer ~o provide information concerning S the aircraft movements along the flight lanes. Position detectors are provided for detecting the position of aircraft in the taxiways and parking areas. However, such system does not teach the use of edge lights along the runways and taxiways along with their associa~ed wiring and it is not able to detect and avoid a possible vehicle! -incursion.
The manner in which ~he invention deals with the disadvantages of the prior art to provide a low co~t infrared vehicle identification system will be evident as the description proceeds.

Sum~ary of the Tn~ention Accordingly, it is therefore an object of this in~ention to provide a low cost infrared system that identifies aircraft or other vehicles on airport taxiways and runways.
It is also an object of ~his inven~.ion to provide at an ai~port a low C03t aircraft or vehicle i.den~ification system using existing edge light as~emblies and associated wiring along runway~ and taxiways.
I~ is another objec~ of this invention to provide an infrared vehicle identification system tha~ generates a graphic display of ~he airport showing the location of all ground traffic includiny direction and velocity data and identifie~ ~uch ground traffic.
The objects are further accompli~hed by pro~iding a vehicle identificatio~ system for identifying aircr~ft and other vehicles on surface pathways incl~ding runways a~d ~-~
other areas of an airport comprising mean~ dispo ed on the aircraft and o~her vehicles for transmitting identification message data, means di~pose~ in each of a plurality ef light as~mbly means on the airport for recei~ing and decoding the message data from the transmittiny means, means for providing power to each of the plurality of light assembly means, means for processing the decoded identification message data generated by the receiving a~d decoding means - ` 2 ~ s~

in each of the plurality of light assembly means, means for providing data communicat:ion b~tween each of the light assembly means and ~he processing means, and the processing mean~ comprise~ means for providing a graphic display of the airport comprising 5ymbol~3 representing the aircraft and other vehicles, ~ach of t]he ~ymbols having the identifica~ion message data di~played. The transmitting means comprises meanS for creating unique mes~age data which includes aircraft and flilght identification~ and infrared mean~ coupled to the me~,age creating means for txansmi~ting coded stream o~ the me~,3age data. The message data further includes position information. The receiving and decoding means comprises ,an infrared sensor. The receiving and decoding means compri;ses microprocessor means coupled to the infrared sensor for d,ecoding the message data. The plurality of light assembly means are arranged in two parallel row along runways and taxiways of the airport.
The ligh~ assembly means comprises ligh~ means coupled to the line~ of the power providing means for lighting the airport, vehicle ~ensing:mean~ or de~ecting aircraft or other vehicles on the airport~ microproce~or mean~ coupled to the receiving and decoding means, the ligh~ means~ the vehicle sensing means and the data co~munication means for decoding the identificatio~ me~sage data, and the data communication mean~ being couple~ to the microproce~sor 21~82 means and the lines of ~he power providing means. The symbols representing aircraft and other v hicles comprise ~, icons having a shape indicating ~ype o~ aircraf~ or vehicle.
The processing means determines a location of the symbols on the graphic display of the aixport in accordance with data ~ recei~ed from the light assembly means.
¦ The object~ are fur~her accomplished by a vehicle¦ identification system for surveillance and identification of ~ aircraft and other vehicles on an airport compri~ing a¦ 10 plurality of light circuits on the airpor~, each of the light circui~ comprises a plurality of light as~embly mean~l means for pro~iding power to each of the plurality of light circuits and to each of the light ass~mbly means, means in each of ~he ligh~ a sembly means or sensing ground traffic on tha airport, means disposed on the aircraft and other vehicles for tranæmit~ing identification me~sage data mean~ di~posed in each of the light assembly means for receiving and decoding the meæsage data from the tran~mitting means, mean~ for processing ground traffic data fro~ the sensing mean~ and decoded message data from each of khe light a~sembly mean~ for pre~entation on a graphic di~play of the airport, means for providing da~a co~munication between each of the light asse~bly means and the processing means, the processing means comprises means for provi~ing such graphic display of the airport c~mprising symbols r~presen~ing the ground traffic, each of th~ ~ymbols having direction, velocity and the identification message data displayed. Each of the light circuits are located along the edges of taxiways or runways on the airport. The S sensing means comprises infrared detectorx. The transmitting means comprises means fo~ crea~ing unique me3sage data which includes aircraft and fligh~
identification, and infrared means coupled to the message creating mean~ for transmit~ing a coded stream of the me~ age data. ~he message data further comprise~ position inform~tion. The receiving and decoding means comprises an infrared sensorq The receiving and decoding means comprise~
microprocessor means coupled to the infrared sensor for decoding the me~sage data. The plurality of light assembly means of the light circuits being arranged in two parallel rows along ru~ways and taxiways of the airport. The light a~se~hly means comprises light means coupled to the lines of th~ power providing mei~n~ for ligh~ing ~he airpor~, the sround traffic sensing m~an for detecting aircraf~ or other vehicle~ on the airport, microproce~sor means coupled to the receiving and decoding means, the light means, the ground traffic sensing means and the data communication means for decoding the identifica~ion mes~age data and processing a detection signal from ~he ground traffic sensing means, a~d -` 211~2 the data communica$ion means being coupled to the microprocessor means and the line~ of the power providing means. The ligh~ a~embly means further comprises a photocell mean~ coupled to the microprocessor means for detecting the light intensity of the light means. The light assembly means further c~mprises a strobe light coupled to the microprocessor means. The processing means comprises redundant co~puteræ for fault tolerance operation. The symbols represen~ing the ground traffic comprise icons having a shape indicating type of aircraft or vehicle. The proces~ing mean~ detsrmines a location of the symbols on the graphic display of the ai~por~ in accordance with the data receive from the light assembly m~ans. The processing means determines a fu~ure path of the ground traffic based on a ground clearance command, the future path being shown on the graphic display. The processing mean~ further comprises mea~s for predicti~g an airport incursion. The power providing means comprises constant ourrent power means for providing a separate line to each of the plurality of light circuits, and network bridge means co~pled to the constant current power mean~ for providing a communication channel to the processi~g mean~ for each line of the con~tant current power means.
The ob~ect~ are further accomplished by providing a method of providing a vehicle identification system for 2 1 ~ 2 identifying aircraft and other vehicles on surface pathways including runways and other areas of an airport comprising the steps of transmitting identification message data with means disposed on the aircraf~ and other vehicles, receiving and decoding the message da~a from the transmitting means with means disposed in each of a plurality of light assembly means on the airport, providing power to each of the plurality of light as~embly means, processing the decoded identification mes~age data generated by the receiving and decoding means in each of ~he plurality of light assembly means, providing data communication between each of the light assembly means and the proce~sing means, and providing a graphic display of the airport with the processing means comprising 8ymbols representing the aircraft an~ other ~ehicles, each of the ~y~bols having the iden~ification messase da~a displayed. The step of transmitting identification message data comprises the steps of cxeating unique message data ~hich includes aircraft and flight identification, and transmitting a coded stream of the message data wi~h infrared means coupled to the mes~age creati~g means. The step of transmitting mes~age data further includes transmitting position information. The step of receiving and decoding the message data includes u~ing an infrared sensor. ~he step of recei~ing and decoding ~he me~sage data further comprises the step of ~ 21~4~2 coupling microprocessor means to ~he infrared sensor for decoding the message data. Th~ step of receiving and decoding the message data with means disposed in the plurality of light assembly means further comprises the step of arranging the plurality of lisht assembly means in two parallel rows along runways and taxiways of the airport.
The step of providing a graphic display comprising symbols representing aircraft and other vehicles further comprises the step of providing icons having a shape indica~ing type of aircraft or Yehicle. q~he step of providing a graphic di~play comprises the step of deterrnining a location of the symbols on the graphic display of the airport in accordance with data rec~ived from the light assembly mearls.

2 1 ~ 2 Brief Description o~ the Drawin~s Other and further features of the invention will become apparent in connection with the accompanying drawings wherein:
FIG. 1 is a block diagram of an airpor~ vehicle incursion avoidance system;
FIG. 2 i~ a block diagra~ of an edge light assembly showing a sensor electronics unit coupled to an edge light o~ an air~ield lighting system;
FIG. 3 is a pictorial diagram of the edge light assembly showing the edge liyht positioned above the sensor electronics unit;
FIG. 4 is a diagram of an airfield runway or taxiway having a plurality of edge light assemblies positioned along each side of the runway or taxi~ay for detecting variou~
size aircraft as shown;
FIG. 5 is a block diagram of the central co~puter ~ystem ~hown in FIG. l;
FIG. 6 shows el2ven ne~work variables used in programming the microproce~sor of an edge light assembly to interface with a sensor, a ligh~ and a strobe light;
FIG. 7 is a block diagram sh~wing an in~erco~nection of network variables for a plurality of edge light assemblies located on both sides of a runway, e ch comprising a sensor olectronics uni~ 10 positioned along a taxiway or runway;

s~ 4 8 2 FIG. 8 ~hows a graphic display o~ a typical taxiway/runway on a portion of an airport as seen by an operator in a control tower, the display showing the location of vehicles as they are detected by the sensors mounted in the edge light assemblies located along ~a~iways and runways;
FIG. 9 is a block diagram of the data flow wi~hin the system shown in FIG. 1 and FIG. 5;
FIG. 10 is a pictorial diagram of an infrared identification system showing an IR transmitter mounted on an airplane wheel strut and an I~ recei~er mounted in an edge light a~sembly of an airport lighting system;
FIG. 11 is a block diagram of an IR transmitter of an IR vehicle iden~ification ~ystem;
FIGo 12 ~how~ a ~op ~iew of the IR transmitter mounted on an airplane wheel strut providing a 195 a~ea o coverage generated by an IR light emit~ing diode array in the IR -:
transmitter;
FIG. 13 shows data fields of a coded data stream transmitted by the IR transmitter;
FIGJ 14 is a blocX diagram of an IR recei~er of the IR :~
vehicle identification sy~tem;
FIG. 15 i~ a flow chart of an IR message routine which is a communicati4n protocol continuously pPrformed in an IR
receiver micropxocessor; and 2 ~ 2 ~ IG. 16 is a flow chart of a vehicle sensor routine which is con~inuou~ly performed in an IR receiver microprocessor.

~4l~2 DeBcription of the Preferred ~mbodiment Referring to FIG. 1 a block diagram of an airport vehicle incursion avoidance system 10 is shown comprising a plurality of light circuit~ 121n, each of said light circuits 181 D comprises a plurality of edge light assemblies 201n connected via wiring 211n to a lighting vault 16 which is connected to a central computer system 12 via a wide area network 14. Each of the edge light ass~mblies 201n compri~es an infrared tIR) detector vehicle sensor 50 (FIG.
~) The edge light assemblies 201n are generally located along ~ide the runway~ and taxiways of the airport with an average 100 foot spacing and are interconnected to the lighting vault 16 by single conductor series edge lis~ht wiring 211n. Eaeh of the edge light circuits 18lnis powered via the wiring 211n by a constant current su~ply 241n located in the lighting vault 16.
Referring now to FIG. 1 and FIG. 2, communication between the edge ligh~ as~emblies 201n a~d the central computer sy~tem 12 is accomplished wi~h LON Bridges 221n interconnecting the edge light wiring 211n with the Wide Area Network 14. Information from a microprocessor 44 located in each edge light a~se~bly 201n i~ coupled to the edge light wiring 211n via a power line modem 5~. The ~0 bridge~ 221n transfer~ mes~age informa~ion from the edge .; . . ~ , . , . . , , , ~ . , " , , ~` 2 ~

light circuits 181n via the wiring 211n to the wide area network 14. The wide area networ~ 14 provides a transmission path to the central computer system 12. These circuit components also provide the return path communications link from the central computer sys~em 12 to the microprocessor 44 in each edge light assembly 201n.
Other apparatus and methods, known to one of ordinary skill in the art, for data communication between the edge light assemblies 201n and the central compu~er system 12 may be employed, such as radio techniques, but ~he present embodiment of providing data communication on the edge light wiring 211n provides a low cost system for present airports.
The LON Bridge 22 may be embodied by devices manufactured by Echelon Corporation of Palo Alto, California. The wide area network 14 may be implemented by one of ordinary ~kill in the art using standard ~thernet or ~iber Distributed Data Interface (FDDI) components. The con~tant current ~upply 24 may be embodied by devic~ manufactured by Crouse Hinds of Winslow, CoDnecticut.
Referring now to ~IG. 2 and FIG. 3, FIG. 3 shows a pictorial diagr~m of the edge light assembly 201n. The edge light assembly 201n comprises a bez~l including an incande~cent lamp 40 and an optional strobe light assembly 48 (FIG. 2) which are mounted above an electronics enclosure 43 comprising a vehicle sensor 50. ~he electronic~

~ 2 enclosure 43 si~s on ~he top of a tubular sha~t extending from a base support 56. The light assembly bezel with lamp 40 and base support 56 may be embodied by devices manufactured by Crouse-Hinds of Winslow, Connecticut.
A block diagram of the contents of the electronics enclosure 43 is ~hown in FIG. 2 which c~mprises a coupling ~:
transformer 53 conne~tPd to the edge light wiring 211n. The coupling transfonmer 53 provides power to both the incandescent lamp 40 via the lamp ~ontrsl triac 42 and the ~:.
microproceSsor power supply 52; in addition, the coupling transfo~mer 53 provides a data communication path betwe~n the power line modem 54 and the LON Bridges 221~ via the edge light wiring 211n. The microprocessor 44 provides the computa~ional power to run the internal software pxogram that controls the edge light assemblies 201n. The microproces~or 44 is powered by the microprocessor power supply 52. Also connected ~o the microprocessor 44 is the lamp control triAc 42, a lamp m~nitoring photo cell 46, ~he optional strobe light assembly 48, the vehicle sen~or 50, and the data communications modem 54, The micropxocessor 44 is usPd to control the incand~scen~ edge light 40 int.ensity and optional strobe light assembly 48. The use of the microprocessor 44 in each light a~sembly 201n allows complete addressable control over every light on the field.
The microprocessor 44 may be embodied ~y a Y~SI device manufactured by Ech~lon Corporation of Palo ~lto, California 94304, called the Neuron~ chip.
Still referring to FIG. 2, the sensor 50 in the present embodiment comprises an infrared (I~3 detector and in other embodLments may comprise other devices such as proximity detectors, CCD cameras, microwave motion detectors, inductance loops, or laser beams. The program in the microprocessor 44 is responsible for the initial $iltering of the sensor data received from the sensor 50 and responsible for the transmission of such da~a to the central computer system 12. The sensor 50 must perform the following functions: detect a stationary object, detect a mo~ing ob~ect, have a range at least half the width of the runway or taxiway, be low power and be immune to false alarms. This system design does not rely on ~ust one type of sensor. Since sen~or fu~ion function are performed within the central computer -Qystem 12, data inputs from all different types of sensors are acceptable. Each sensor relays a different vie~ of what i8 happening on the airfield and the central computer system 12 combines them. ~here are a wide range of sensor~ that may be used in thi~ system.
Ag a new sensor type becvmes available, i~ can be integrat~d -~
into this system with a minimum of difficulty. The initial sensor u~ed is an IR proxLmity detector based around a piezoelectric s~rip. The~e are the kind of sensors you use at home to turn on your flood lights when heat and/or movement is de~ec~ed. When the sensor ou~put provide~ an analog signal, an analog-to-digital converter readily known in the art may be us,ed to interface with the microprocessor 44.
Another proximity detector tha~ can be used is based around a microwave!S;unn diode oscillator. These are currently in use in such applications as Intrusion Alarms, Door Openérs, Distanee Measurement, Collision Warning, Railroad Switching, ~atc. These types of sensors have a drawback becau~e they are not passive devices and care needs to be taken to selec:t frequencies that would not interfere with other airport e~uipment. ~inally, in locations such as the hold position l~nes on taxiway~, solid state laser and detector combinatio}ls could be u3ed between adjacent taxiway ligh~s. The e sensor systems create a beam that when broken would identi~Ey the location of the fron~ wheel of the airplane. This tn?e of detector would be used in those locations where the absolute po~i~ion of a vehicle was needed. The laser beam would be modulated by the microprocessor 44 tc\ avoid the detector being fooled by any other stray radi2tic~n.
Referring to F:lG. 2 and FIGo 4~ a portion of an airport runway 64 or ta~ ay i~ shown ha~ing a plurality of edge light as~emblie~ 20~a positioned along each side of the 2 ~

runway or taxiway for detecting various size airplan~s or vehicles 60, 62. The dashed lines represent the coveraye area of the sensors 50 located in each edge light assembly 201B positioned along each ~ide of the runway 64 or taxiway ~o insure detection of any airplane 60, 52 or other vehicles traveling on such runway 64 or ~axiway. The edge light assemblies 201_n comprising the sensor 50 are logically connected together in such a way that an entire airport is sensitized to the movement of vehicles. Node to node communication takes plare to verify and iden~ify the location of the vehicles. Once thi~ is done a me~sage is sent to the central computer sy tem 12 reporting the vehicles location. ~dge light~ assemblies (without a sensor electronics unit 43) and taxiway power wiring currently exist along taxiways, runways and open areas of airports, ~:
therefore, the sensor electronics unit 43 i~ readily added to existing edge lights and existing taxiway power wiring without the inconvenience and expense of closing down runways and taxiways while installing new cabling.
Referring now to FIG. 1, FI~. 5, FIG. 8 and FIG. 97 the central computer system 12 is generally loca~ed at ~ control tower or terminal area of an airport and is interconnected ~:
to the LON Bridges 221n loca~ed in the ligh~ing vault 16 with a Wide Area ~etwork 14. The cen~ral computer system 12 comprises two redundant compu~ers, compu~er #1 26 and 2~ ~ ~4~2 computer #2 28 for fault tolerance, the display 30, speech syn~hesis units 29 & 31, alert lights 34, keyboard 27 and a speech recognition unit 33, all of these elements being interconnected by the wide area network 14 for the transfer of information. The two computer~ 26 and 28 communicate with the microproc~ssors 44 located in the edge li~ht assemblies 201n. Data received from the edge light assembly 201n microproces~ors 44 are u~ed as *n input to a sensor fusion software module 101 (FIG. 9~ run on the redundant computers 26 and 28. The output of the sensor fusion software module 101 operating in the computers 26, 28 is used to drive the CRT display 30 which displays the location of each vehicle on the airpor~ taxiway and runways as shown i~ FIG. 8. The central computer system 12 may be embodied by device~ manufacturPd by IB~ Corporation of White Plains, New ~ork. The Wide Area Network 14 may be embodied by devicPs manufactured by 3Com Corpor~tion of Santa Clara, California. Th~ speech synthesis units 29, 31 and the ~peech recognition unit 33 may be embodied by devic~s manufactured by BBN of Cambridgel Massachusetts.
The speech synthesis unit 29 is coupled to a speaker 32. Limited information is sent to the speech synthesis unit 29 via the wide area network 14 to provide the capa~ility to gi~e an air traffic controller a verbal ~lert.
Th~ speech synthesis unit 31 is coupled to a radio 37 having - ` 2 ~ 2 an antenna 39 to provide the capability to give the pilots a verbal alert. The voice commands from th~ air traffic controller to the pilots are captured by microphone 35 and ~ent to the pilots via radio 36 and antenna 38. In the present embodiment a tap is made and the speech information is sent to both the radio 36 and the speech recognition unit 33 which i~ programmed to recognize the limited air traffic control vocabulary used ~y a controller. This includes airline names, aircraft type, the numbers 0-9, ~he name of the taxiway~ and run~ays and various short phra~es ~uch a~
"hold short~ 'expedite'' and ~give way to.~ The output of the speech recognition unit 33 is fed to the computers 26, 28.
Referring again to FIG. 2, the power line modem 54 provides a data communication path over the edge light wiring 211 ~ for the microproce~sor 44. This two way path is ~--used for th~ passing of command and control inform~tion betwee~ the various edge light assemblies 201n and the central computer system 12. A power line transceiver module in the power line modem 54 i~ u~ed to provide a data channel. These modules u~e a carrier current approach to create the data channel. Power line modems ~hat operate at -~
carrier frequencies in the 100 to 450 ghz band are available from many manufacturers. These modems provide digital communication pa~hs at data rates of up to 10,000 bits per 211 4~82 second utilizing direct sequ~nce spread spectrum modulation.
They conform to FCC power line carrier requirements for conducted Pmissions, and can work with up ~o 55 dB of pow0r line attenuation. The power line modem 54 may be embodied by a device manufactured by Echelon Corporation of Palo Alto, California 94304, called the PLT-10 Power Line Transceiver Module.
The data channel prsvides a transport layer or lowest layer of the open system interconnec~ion (OSI) protocol used in the data network. The Neuron~ chip which Lmplemen~s the microprocessor 44 contains all of the firmware required to implement a 7 layer OSI protocol. When interconnected via an appropriate medi~m the Neuron~ chips automatically communicate wi~h one another using a robust Collision Sense Multiple Access (CSMA~ protocol with forward error corrections, error checking and automatic retransmission of missed mes~age (ARQ3.
The command and control information is placed in data packets and sent over the networX in accordance with the 7 Layer OSI protocol. All mes~age~ generated by the microprocessor 44 and destined for the cen~ral computer system 12 are received by the network bridge 22 via the power line~ 211n and routed to the central computer system 12 over the wide area network 14.

~.
The Neuron~ chip of the microprocessor 44 comprises three processors (not shown) and the firmware required to suppor~ a full 6 layer open systems interconnection ~OSI) protocol. ~he user is alloca~ed one of the processors for the ap~lication code. The other two processors give the application program access to all of the o~her Neuron~ chip~
in the network. This access create~ a Local Operating Network or LON. A LON can be thought of as a high level local area network LAN. The use of the Neuron~ chip for the impleme~tation of this invention, reduces the amount of custom hardware and software that otherwise would have to be developed.
Data from the sensor electronic unit 43 of the edge light assemblies 201n is coupled to the central computer sy~tem 12 via the existing airport taxiway lighting po~er wiring 21. U~ing the exi~ting edge light power line to transfex the sensor da~a into a LO~ network has many advantages. As previously pointed out, the reu~e of the e~isting edge lights elLminates the inconvenience and expense of closing down runways and taxiways while running new cable and provides for a low cost system.
The Neuron~ chip allows the edge light assemblies 201n to automatically communicate with each other at the applications level. This is accomplished ~hrough network variables which allow individual Neuron0 chip~ to pass data 2~

2 ~ 8 2 between ~hemselves. Each Neuron~ 'C~ program comprises both local and network variables. The local variables are used by the Neuron program as a ~cratch pad memory. The network variables are used by the Neuron~ program in one of two ways, either as a network output variables or a network input variables. Both kinds of variables can be initialized, evaluated and modified locally. The difference comes into play in that once a network output variable is modified, network message~ are automatically sent to eaeh network input variable that is linked ~o tha~ output variable. This variable linking is done at installation tLme. As ~oon as a new ~alue of a network input variable is received by a Neuron~ chip, the code i5 vectored off to take appropriate action ba~ed upon the value of ~he network input variable. The ad~antage t9 the progr~m is that this me~sage pa~sing scheme i~ entirely ~ran~parent since the message passing code is part of ~he embedded Neuron~ operating system.
Referring now ~o FIG. 6, eleven network variables have been identified for a sensor program in each microprocessor 44 of the edge light assemblies 201~. The sensor 50 function has two output variables: prelLm_detect 70 and confirmed_detect 72. The idea here i~ to have one output trigger whenever the sensor 50 det~cts movement. The other output does not trigger unless ~he local 3ensor and the - - - 2 1 ~ 2 sensor on the edge light a~ro~s the runway both spot movement. Only when the detection is coninmed will the signal be fed back to the central computer system 12. Thi~
technique of confirmation helps to reduce false alarms in 1 5 order to Lmplement this techni~ue the adja~ent sensor 50 has an inpu~ variable called ad~_prelLm_detec~ 78 that is used to receive the other sensors prelim detect output 70. Other input variables are upstream detect 74 and downstream_detect 76 which are used when chaining adjacent sen~ors together.
Also needed i~ a detec~or_sensitivity 80 input that is used by the central computer system 12 to control the detection ability of the sen~or 50.
The incandescent light 40 require~ two ne~work ¦ variable~, one input and the other an output variable. The 1 15 input variable light_level 84 would be used to control the ligh~s brigh~ness. The range would be O~F or 0% all the way to FmLL O~ or 100%, This range from 0% ~o 100% would be made in 0.5% s~eps. 5ince th edge light assembly 2O1 D al~o contains the photocell 46, an output variable light failure 84 is created t~ ~ignal that the lamp did no~ obtain the de~ired brightnes~.
The strobe light 48 requires three input variables.
The ~trobe-mode 86 ~ariable is used to select either the OFF, SEQUENTIA~, or ALT~RN~TE fla~h mo e~. Since the two fla~h modes require a distinct pattern to be created, two 2 1 ~ 2 input variables active_delay 88 and flash_delay 90 are used to tLme align the strobe flashes. By setting these individual delay factors and then addressing ~he Neuron chips as a group, allows the creation of a field stro~e pattern with just one command.
Referring now to FIG. 7, a block diagram of an interconnection of ne~work variables for a plurali~y of edge light assemblies 201n located on both sides of a runway is shown, each of the edge light assemblies 201n comprising a microproce~sor 44. Each ~euroni-~ program in the microprocessor 44 i5 designed with certain networX input and output variables. The user writes the code for the Neuroni~
chip~i in the microprocessor 44 a~suming tha~ the inputs are supplied and that the outputs are used. To create an actual network the user has to ~wire up~ the network by interconnecting the individual nodes with a software linkir. The resulting distributed process is ~est shown in ~chematic foxm, and a portion of the network in~erconnec~
matrix is shown in ~igure 7. The prelim_de~ect 70 output of a sensor node 441 is connected to the ad; prLmary_detect 92 input of the sensor node 444 across the taxiway. This i~
u~ed as a means to ~erify actual detections and eliminate falRe reports. The communication~ link between these~two nodes 441 and 444 i~ part of the distributiPd procei~sing.
~he two nodes communicate iImong them~elvies witho~lt in~olviny g ,, ~ : '~-': ' ., i '" ` ': , the central computer system 12. If in the automa~ic mode or if instructed by the controller, the system will also alert the pilots via audio and visual indications.
Referring again to FIG. 1 and FIG. 4, the central computer system 12 tracks the movement of vehicle~ as they pass from the ssnsor S0 to sensor 50 in each edge light assembly 201n. Using a varia~ion of a radar automatic track algorithm, the system can ~rack position, velocity and heading of all aircraft or vehicles based upon the sensor 50 readings. New vehicles are entered into the system either upon leaving a boarding gate or landing. Unknown vehicles are also trac~ed automatically. Since taxiway and runway lights are normally across from each other on the pavement ~as shown in FIG. 4 and FIG. 7), the microproce~sor 44 in each ~ge lights assembly 201n is programmed to combine their sensor 50 i~puts and agree before reporting a contact.
A further refinement is to have the microprocessor 44 ch~ck with the edge light assemblies 201~ on ei~her side of them to see if their sensors 50 had detected the vehicle. This allows a vehicle to be handed off from sensor elsctronic unit 43 to sensor electronic unit 43 of each edge light assembly 2 l-n as it travels down the taxiway. This also as~ures that vehicle position reports remain consistent.
Vehicle veloci~y may also be calculated by using the 2~

~1~4~2 ! distance between sensors, the sensor pat~ern and the time ,' between detections.

¦ Referring to FIG. 5 and FI~. 8, the di~play 30 is a ~ color monitor which provides a gr~phical display of the ¦ 5 airport, a portion of which is shown in FIG. 8. This is accomplished by storing a map of ~he airport in the redundant computers 26 and 28 in a digital format. The display 30 show~ the loca~ion of airplanes or vehicles as they are de~ected by the sensors 50 mounted in th edge light a~sembli~s 201_~ along each taxiway and runway or other airport ~urfac~ areas. All aircraft or vehicles on the airport surface are displayed as icons, wi~h the shape of the iccns being determined by the vehicle type. Vehicle position is shown by the loca~ion of the icon on the screen.
Vehicle direction is shown by ei~her the orienta~ion of the icon or by an arrow e~ana~ing from the icon. Vehicla status is conveyed by the color of the icon. The future path of the vehicle a~ provided by the ground clearance command entered via the controller~ microphone 35 is shown ac; a ~0 colored line on ~he display 3U. The status of all field lights including each edge light 201n in each edge light circuit 181n is shown via color on the display 30.
Use of ob~ect orientated software pro~ides the basis for building a model of an airpor~0 ~he automatic - 2 ~ 8 ~

inheritance feature allows a data structure to be de~ined once for each object and then replicated automatically for each in~tance of that object. Automatic flow down assures that elements of the data base are not corrupted due to typing errors. It also assures that the code is regular and structured. ~ule ~ased object oriented programming makes it difficult to create unintelligible "spaghetti code.l' Object oriented programming allows the runways, taxiways, aircraft and sensors, to be decoded directly as objects. Each of these objects contains attributes. Some of these a~tributes are fixed like runway 22R or flight UA347, and some are variable like vehicle statu~ and position.
In conventional programming we describe the attributes of an ob~ect in data structures and then describe the behaviors of the object as procsdures that operate on those data ~tructures. Obiect oriented programming ~hif~s the emphasi~ and focuses first on the data ~tructure and only secondarily on the procedure~. More importantly, object oriented programming allow~ us to snalyze and design programs in a natural manner. We can thin~ in term~ of runways and aircraft in~ead of focusing on ei~her the behavior or ~he data xtructures of ~he runways and aircraft.
Table 1 shows a list of ob~ect~ with corresponding attributes. Each physical object that i5 important to the ru~way incursion problem i~ modeled. The basic airplane or --" 211~82 vehicle tracking algorithm is shown in Table 2 in a Program Design Language ~PDL). The algorithm which handles ~ensor fu~ion, incursion avoidance and safety alerts i9 shown in a ~ ~ingle program even though it i~ Lmplemented as distributed ¦ 5 system using both the central computer sy~tem 12 and the I sensor microprocessor~ 44.
~aBLE 1 a~CT ATTRIBUTB DBSC~aN
Sensor ~;ocation X s Y coordinates of sensor 0 Clrcuit ~aC wiring circuit n~ns h namber .. Unique a~dress ~et address or thll3 sensor ~md its m~te Lamp inten6ity 0~ to 100~ ln 0.59~ steps S~robe stntus ~link rate/off -Strobe-delay Prom start signnl Sensor status ~st~ct/no d~tect Sensor typa IEI, laser, proximity, etc.
Runway Name 22R, 27, 33L, etc.
~ocation X & Y coordln~tes of stnrt of center lina Iength In feet Width In feet Diraction In degrees from north Status ~ot nctive, active ta~soff, ctive lnnding, alar~
Sensors ~MV) 1ist of lightsJsensors nlong this runway Interssctions (~V) List of intersactions Vehiclea ~ist of vshiclss on th~ runway Trlxi~ay Name ~l~e of tnxlway locutlon h ~ Y coordinat0s of start of centsr lins Lsngth In f~et Width In ieet Dirsction In d~grees fr~m north Status Not aGtive, active, alarm Sensors ~!SV) I,i~t of interssctions llold I,ocntions I,ist oi~ holding loontions Vehiclss ~IV) I.ist o1' veh~clE~ on the runwny r~ 21 1 4 ~ 8 ~

In~er~eo~ion Name Intersectlon NaDe Location In~orsectlon of two center lines St~tus V~ca~t/Occupi~d So~sors (~V) Liat o~ ~en~ora creatLng lntersection border Aircra~t AlrlLne Unitad ModQl 727-200 Tall-number N3274Z
~pty welght 9.5 ton~
I Frulght welght 2.3 to~
¦ 10 Fu~l woight 3.2 tons ¦ T4p ~pe~d 598 mph Vl ~peed 100 ~ph V2 spo~d 140 mph Ae~el~r~tLon 0.23 9'8 D~coleratlon 0.3~ g's MY - MultL-v~rl~blo or array Table 2 while (fore~er) ¦ if tedge light show~ a de~2ction) ¦ ¦ i (adjacent light al~o ahow~ a detection sen~or fusion) ¦ ¦ ¦ j* CONFIRMED DETECTION */
¦ ¦ ¦ if (previou~ block ahowed a detection) ¦ ¦ ¦ ¦ /* AC OE PT HANDOFF */
¦ ¦ ¦ ¦ Update aircraft poaition and speed 1 1 1 el~a ¦ ¦ ¦ ¦ ~* ~aY BE AN ANYMAL OR SERVI OE TRUCK ~/
¦ ¦ ¦ ¦ Alert operator to po~ible incursion ¦ ¦ ¦ ¦ /* NaY BE AN AI~CRAFT ENTERI~G T~B SYSTEM */
¦ I I ¦ Start a ~ew track ¦ ¦ el~e ¦ ¦ ¦ Reque~t 0tatu~ ~rom adjacent light ¦ ¦ ¦ if (Adjacent light i~ OR) ¦ ¦ ¦ ¦ /* NON CONFIRMED DETECTION */
I I I elr~e ¦ ~ ¦ ¦ Flag ad~acent light for repair ¦ ¦ ¦ endif ¦ ¦ endif ¦ endi~
¦ if (Edge light lo~er~ a detection AND atat-l~ ir~ OK) ¦ ¦ if ~Naxt block sho~ed a detection) ~ P~OPER HANDOFF */
I I elr~
¦ ¦ ¦ i~ (vehicle apsed > - takeQff) ~ andof~ to departuro control ¦ ¦ ¦ el~e ¦ ¦ ¦ ¦ /* MI~SING HaNDOFF *~
Alert operator to po~ible incur ion endif I I endif ¦ ~ndif ¦ /* C~ECR FOR POSSIBLE COLLIS~ONS ~/
~or (all trac~ed aircra~t) I j Plot futur~ positLon ¦ ¦ i (po~ition conrlict) l l l Alert operator to por~ible incur~ion ¦ ¦ endif I endif ¦ Update display endwhile R~3f erring agaill to ~IG . 1 and FIG . 2; the control of taxiway lighting lnten31ty i~ u~ually done by plas::ing all 8 ~

the lights on the same series circuit and then regulating the curren~ in that circuit. In the presen~ embodLment the intensity of the lamp 40 is controlled by ~ending a message with the light intensity value to the microproc~ssor 44 located within the ligh~ assembly ~l-n . The message allows for intensity settings in ~he range of 0 to 100% in 0.5%
steps. The use of photocell 46 to chec.k the light output allows a return message to be 3ent if the bulb does not respond. This in turn generat~s a maintenance repor$ on the j 10 ligh~. The strobe light 48 provides an additional optional capability under program control of the microproce~sor 44.
~ach of the microproces~ors 44 in the edye light assemblies 20 is individually addressable. This means every l~np on the field is controlled individually by the central computer system 12.
The system 10 can be programmed to provide an Active Runway Indicator by using the s~robe lights 48 in those edge light assemblie~ 201n located on the runway 64 to continue the approach light ~rabbit~ strobe pattern all the way down the runway. This ligh~ing pat~ern could be turned-on as a plane i~ cleared for landing and then turned-off after the aircraft has touched down. A pilot approaching the runway along an intersecting ta~iway would be alerted in a clear and unambiguous way that the runway was ac~i~e and should not be crossed.

2 ~ g 2 If an incursion was detected the main computers 26, 28 could switch the runway strobe lights 48 from the "rabbit"
pattern to a pattern that altern~*ively flashes either side of the runway in a wig-wag fashion. A switch to this pattern would be int~rpreted by ~he pilot of an arriving aircraf~ a~ a wave off and a signal to go around. The abrupt switch in ~he pattern of the strobes would be in~ta~taneously picked up by the air crew in time for th~m to initiate an aborted landing procedure.
During Category III weather conditions both runway and taxiway visibility are very low. Currently radio ba~ed landing systems are used to get the aircraft from final approach to the ru~way. Once on the runway it is not always obvious which taxiway~ are to be used to reach the airport terminalO In system 10 the main computers 26,28 can control the taxiway lamps 40 as the mean~ fsr guiding aircraft on the ground during ~AT III conditions. Since the intensity of the taxiway lamps 40 can be contrvll~d remotely, *he lamp~ just in fron~ of an aircraft could be intensified or flashed as a means of guiding it to the terminal.
Alternatively, a short sequence of th~ "rabbit" pattexn may be programmed into the taxiway strobe~ ~ust in front of the aircraft. At interseotions 7 either ~he unwant~d p ths may have their la~p8 *urned off or ~he en~rance *o the proper section of taxiway may fla~h directing the pilot ~o 2 ~ 2 head in ~hat direction. Of course in a smart system only those lights directly in front of a plane would be ~:
controlled, all other lamps on ~he field would remain in their normal mode. .
S Referxing now to FI&. 9, a block diagram is shown of the data flow within the ~y~tem 10 (as ~hown in FIG. 1 and FIG. 5). The software modules are shown that are used to proces the da~a wi~hin the computers 26, 2B of the central computer system 12. The tracking of aircraft and other vehicles on the airport operates under the control of ~ensor fu~ion software module 101 which resides in the computers 26, 28. The sensor fu~ion software module 101 receives data ~rom the plurality of sensors 50, a sensor 50 being located in each edge light assembly 201n which reports the heat level detected, and this software module 101 combines this information ~hrough the use of rule ba~ed artificial intelligence to create a complete picture of all ground traffic at ~he airpor~ on a display 30 of the central co~puter sy8t8m 12.
The tracking algorithm starts a trac~ upon the first report of a sen~or 50 detecting a heat leYel that is above the ambient background level of radiation. This d tection is then verified by ch~cking ~he heat level reported by the ~ensor directly acro~s the pavement from ~he first reporting sensor. Thi~ secondary reading is used to confirm the vehicle de~ected and to elLminate false alarms. After a vehicle has been con~irmed ~he sensors adjacent to the firs~
reporting sensor are queried for changes in their detected ! heat level. ~s soon as one of the adjacen~ sensors detects I S a riss in heat level a direction vector for the vehicle can :¦ be established. This process continues as the vehicle i3 I handed off from sensor to sensor in a bucket brigade fashion ;1 as shown in FIG. 7. Yehicle speed can be roughly determined by calcul~ting the tLme be~ween vehicle detection by adjacent sensors. Thi information i8 combined with : information from a sy~tem data base on the location of each sensor to calculate ~he veloci~y of the target. Due to hot e~haust or ~et blast, the sensors behind the vehicle may not return to a background level Lmmediately. Because of these condition, the algorithm only uses the first four sensors (~wo on either side of the taxiway) to calculate the vehicles position. The vehicle is always ass~med to be on the centerline of the pavement and betwee~ the first four reporting sensors.
Vehicle identification can be added to the tra~k either manually or automatically by an automated source that can identify a vehicle by its position. An ex~mple would be prior knowledge of the next aircraft to land on a particular runway. Tracks are ended when a vehicle leaves the detection system. This can occur in one of two ways. The first way is ~hat the vehicle leaves ~he area covered by the sensors 50. This is determined by a vehicle track moving in the direction of a gateway sensor and ~hen a lack of detection after the gateway sensor ha~ lost contact. A
second way to leave the detection sy~tem is for a tr~ck to be lost in the middle of a sensor ~rray. Thi5 can occur when an aircraft departs or a v~hicle runs onto the grass.
Takeoff scenarios can be de~ermined by calculating the speed of the vehicl~ just before detection was lo~t. If the vehicle speed was increasing and above rotation speed then the aircxaft is assumed to have taken off. If not then the vehicle is assumed ~o have gone on to the grass and an alarm i8 sounded.
Referring to FIG. 5 and FIG. 9, the ground clearance routing function is performed by the ~peech r~cognition unit 33 along with the ground clearance compliance verifier ~oftware module 103 running on the computers 26,28. ~his software module 103 comprises a vehicle iden~ification routine, clearance path rou~ing, clearance checking routine 2~ and a path checking routine.
~he vehicle identification routine is u3ed ~o receive the airline name and flight number (i.e. ~Delta 374") from the speech recognition uni~ 33 and it highligh~s the i~on of that aircraft on the graphic display of the airport on display 30.

-` 2 1 ~ 2 The clearance path routine takes the remainder of the controller~s phrase (i.e. "outer taxiway to echo, hold short of runway 15 Left~) and provides a graphical display of the clearance on the display 30 showing the airport.
The clearance checking routine checks the clearance path for possible conflict with other clearances and ¦ vehicles~ I a conflic~ is found the portion of the path that would cause an incursion is highligh~ed in a blinking red and an audible indication is given to the controller ~i~
speaker 32.
Th0 path checking routine checks the actual path of the vehicle as detected by the sen~ors 50 after the clearance path has been entered into the computerC 26, 28 and i.t monitor~ the actual path for any deviation. If this routine detects that ~ vehicle has strayed from the a~signed course, the vehicle icon on the graphic display of the airport flashes and an audible indicator is given to ~he con~roller ~-:
via speaker 32 and optionally the vehicle operator via radio 37.
The airport vehicle incursion avoidance system 10 oparates under the control of safety logic routines which reside in the collision detection software module 104 running on c~mputers 26, 28. ~he safety logic r~utines receive data from the sensor fusion software module 101 location program via the tracker software module 102 and 2 1 ~ 2 I interpret this information through the use of rule based I artificial intelligence to predict posæible collisions or I runway incur~ions. This in~ormation is then used by the I central computer sys~em 12 to aler~ tower controllers, aircraft pilots and ~ruck operator~ to the possibility of a I runway incursion. The tower oontrollers are alerted ~y the ¦ display 30 along with a computer synthesized voice message via speaker 32. Ground traffic is aler~ed by a combination of traffic lights, flashing lights, stop bars and other alert lightis 34, lamp8 40 and 48, and computer generated voice commands broadcast via radio 36.
Knowledge ba3ed problem~ are also called fuzzy problems and their solution~ depend upon both program logic and an interface engine tha~ can dynamically create a decision tree, selecting which heuristics are most appropriate for the ~pecific oase being considered. Rule based systems broaderl the scop~ of possible applications. They allow designers to incorporate judgement and experience, and to take a consisten~ solution approach across an entire problem ~0 8et.
The programming of the rule based i~cursion de~ections software i8 very straight forward. The rules are written in ~nglish allowing th experts, in this case the to~er personnel and the pilo~s, to review the system at an under~tandable level. Another feature of the rule based - ~ 2 ~

system is that the rules stand alone. They can be added, deleted or modified without affecting the rest of the code.
This is almost impossible to do with code that is created from scratch. An example of a rule we mi~ht use is.
If (Runway Statu~ = Active) then ~Stop Bar Lighta = RED).
This is a very ~Lmple and ~traight forward rule. It ~tands alone requiring no extra knowledge except how Runway_Statu~
is created. So let's make some rules affecting Runway Statu~.
If ~Departura = APPROVED) or ~Landing = I~INENT), then (Runway Statu~ = A~TIVE). ~
For incursion detection, another rule is: -If (Runway_St~tu~ = A~TIVE~ and tInter~ction = OCCUPIED), th~n (Runway Incur~ion = TRUE).
Next, deteet ~hat an inter~ection o$ a runway and taxiway are occupied by the rules:
I~ ~Inter~ction_Sen~or~ = DET~CT), then (I~ter~ectLon = OCC~PI~D). ~:
To predict that an aircraf~ will run a Hold ~osition stop, the following rule is created:
If (Aircra~t_Stopping_Distance > Di~tance_to_Hold Poaition), th~n ~Inter~ectLon = OCCUPIED)~
In order to show that rules can be added wi hout affecting the rese~ o~ the program, assume that af~er a demons~ration of the sy~ em 10 to tower controllers, they 2 ~ 2 , decided that they wanted a ~Panic Button~ in the tower to - override the rule based software in case they spok a safety ,~ violation on ~he ground. Beside~ installing the button, the ;ll only other change would be to add this extra rule.
If (Par~ button = PRESSED), th~n (Runway Incursion = TRIJE).
It is readily seen that the central rule based computer program i8 very straight forward to create, understand and modify. As types of incursio~s are defined, the system 10 . 10 can be upgraded by adding more rules.
Referxing again to FIG. 9, the block diagxam shows the data flow between the functional elemen~3 within the system 10 (FIG. 1). Vehicles are detected by the sensor 50 in each o~ the edge light assemblies 201~. This information is pas~ed over the local operatiny network (LON) via edge light wiring 211n to the LON bridge~ 221n. The individual message ¦ packets are then passed to ~he redundant computers 26 and 2B
o~er the wide area ne~work (WAN) 14 to the WAN interEace 108. After arriving at the redundant computer~ 26 and 28, the message packet is checked and verified by a mes~age parser software module 100. The contents o~ the message are then sent to the sensor fusion ~oftware module lOlo The sensor fusion softwar2 ~odule 101 is used to keep track of the status of all the sensors 50 on the airport; it ~Eilters and verifies the data from the airport an stores a 21 14~2 representative picture of th~ sensor array in a memory.
This information is used directly by the display 30 to show which senssrs 50 are responding and used by the tracker sof~ware module 102. Th~ tracker software module 102 uses the sensor status information to determine which sensor 50 reports corre3pond to actual vehicles. In addition, as the sen~or reports and status chanae, the tracker software module 102 identifies movem~nt of the vehicles and produces a target location and direction output. Thi~ information is used by the display 30 in order to display the appropriate vehicle icon o~ t~e screen.
The location and direction of the vehicle is also used by the collision detection software module 104. This module checks all of the vehicles on the ground and plot~ their expected course. If any two taryets are on inter~ecting paths, this software mo~ule generates operator alerts by u3ing the display 30, the alert ligh~s 34, ~he ~peech synthesis unit 29 coupled to the associated ~peaXer 32, and the speech 3ynthesi~ uni~ 31 coupled to radio 37 which is coup}ed to antenna 39.
Still referring to FIG. 9, ano~her user of target location and position data i8 the ground clsarance compliance verifier ~oftware module 103. This software module 103 receives the ground clearance command~ fro~ the controller~ 3 mîcrophone 35 via ~he speech recogni~ion unit ~3 --` 2 ~ 2 ¦ 33. Once the cleared route has been determined, it is stored in the ground clearance compliance verifier software module 103 and used for comparison to the actual route taken by the vehicle. If the information received from the tracker software module 102 shows that the vehicle has de~iated fxom it~ assigned course~ this ~Zoftware module 103 generates operator alerts by using the display 30, the alert lights 34, the speech synthe~is unit 29 coupled to speaker 32, and the ~peech synthesis unit 31 coupled to radio 37 which iZ~ coupled to antenna 39.
The keyboard 27 is connected to a keyboard parser softwar0 module 109. When a command has been verified by the keyboard par~Zer software modul~ 109, it is used to change display 30 option~ and to reconfigure ~he sen~or5 and network parame~ers. A network configuration data base 1~6 is updated with these reconfiguration commands. This i~formatioZn is then turned into LON message packets by the command message generator 107 and seZnt to ~he edge light assemblies 201n via the WAN interfac~ 108 a~d ~he LON
bridge8 22 l-n ~
Referring now to FIG. 1 and FIG. 10, FIG~ 10 shows a pictorial diagram of an infrared vehicle identification sZystem 109 invention comprising an infrared (IR) tran mitter 112 mou~ted on an airplane 110 wheel Ztrut 111 and an IR
reZceiver 128 which comprises a plurality of edge light --` 2 ~ 8 2 assemblies 201n of an airport lighting system also shown in FIG. 1. The combination of the IR transmi~ter 112 mounted on aircraft and/or other vehicles and a plurality of IR
' receivers 128 loc~ted along runways and taxiways form the ¦ S infrared vehicle identification system 109 for use at airports for the safety, guidance and control of surface vèhicles in order to provide positive dletec~ion and identification of all aircraft and other vehicles and to preven~ runway incursions. Runway incursions generally occur when aircraft or other vehicles get onto a runway and I conflict with aircraft cleared to land or takeoff on that ¦ same runway. All such incursions are caused by human error.
¦ Referring now to FIG. 11, a block diagram of the IR
~i transmitter 112 is ~hown comprisiny an embedded microprocessor 118 having DC power 114 inputs ~rom the ~ aircraft host or vehicle on which the IR transmit~er 112 is ¦ moun~ed and an ID switch 116 within the aircraft for entering vehicle identificatio~ data which is received by ~ the IR transmit~er 112 on a ~erial line. Vehicle po~ition ¦ 20 information is provided to the IR transmit~er 112 from a vehicle po~ition receiver 117 which may be embodied by a global positioning system (GP~) receiver readily known in the art. The output of embedded microproce~sor 118 feeds an IR emitter comprising a light emitting diode (LED) array 120. When power i~ applied to ~he IR transmitter 112, the 211~482 microproces~or con~inuously outputs a coded data stream 121 IFIG. 13) which i3 transmitted by the IR ~ED array 120. The embedded microprocessor 118 may be embodied by microprocessor Model MC 6803 or equivalent manufactured by Motorola Microprocessor Products of Austin, TPxas. The IR
LED array 120 may be embodied by IR LED Devices manufactured by Harris Se~iconductor of ~Ielborne, ~lorida.
Referring now to ~IG. 12, a top view of the IR
transmitter 112 comprising the IR LED array 120 mounted on an airplane wheel strut 111 is shown. The IR ~ED array 120 comprises a plurality of high power hEDs each having a beam width of 15. By placing thirteen LEDs in an array, a 195 area can be co~ered. The IR LED array 1~0 illuminates edge light assemblies 20l4 along the edges of the runway 64.
Each of the edge light assemblies 20l4 comprises an IR
receiver 12 8 .
Referring now to FIG. 13, the coded da~a stream emitted from the IR transmitter 112 compriRes six separats fields.
The first field i~ called ~Lming pat~ern 122 and comprises a sst of equally spaced pulses. The second field is called unique word 123 which marks the beginning of a message. The third field is called character count 124 which specifies :~
the number of character~ in a message. ~he fourth field is called vehicle identifica~ion number 125. The fif~h field i8 called ~ehicle posi~ion 126 and provides latitude and - 21 ~4~L~2 longi~ude information~ The sixth field is called message checks~m 127. The equally spaced pulse~ of the timing pattern 122 allow the IR receiver 128 to calculate th~ baud rate of a transmitted message and automatically ad~ust its internal timing to compen~a~e for either a doppler shi~t or an offset in clock frequency. The checksum 126 field allows the IR receiver 128 to find the byte boundary. The character count 124 field is used to alert the IR receiver 128 in the edge light as~emblies 20l4 as to the leng~h of the message being received. The IR receiver 128 uses this field to determine when the message has ended and if the message was truncated.
The vehicle identification number 125 field comprises an airline flight number or a tail number of an aircraft or a license number of other vehicles. The actual number can be alpha-numeric since each charac~er will be allocated eight (8) bits. An ASCII code which is known to those of ordinaxy skill in the ar~ is an example of a code type that may be used. ~he only constrain~s on the Yehicl ID number is that it be unique to th~ vehicle and ~ha~ it be entered in the airport' 8 central computer data base to facilitate automatic identîfication. The checksum 127 guarantees that a complete and corre~t message is received. If the message is interrupted for any reason, such as a blocked beam or a 2S change in vehicle direction, it is in~tantly detected and ~ 2 the reception voided. This procedure reduces the number of false detec~s and guarantees that only perfect vehicle identifisation m~ssages are passed on to the central computer system 12 at the airport tower.
~eferring now ~o FIG.1, FI~. 2, FIG. 10 and FIG. 14, a block diagram of th~ IR receiver 128 i~ sho~m in FI~. 14 which comprises and I~ sensor 130 connected to an edge light a~sembly 201n shown in FIG. 1, PIG. 2 and FIG. 10, on an airport. In FIG. 14, only ~he relevan~ portion of FIG. 2 are ~hown, but it should be understood that all of the elements of the edge li~ht assembly 201n shown in FIG. 2 axe considered pre~ent in ~IG. 14. The IR receiver 128 comprises the IR sen~or 130 which receives the coded data stream 121 (FIG. 13) from the transmitter 112. The output of the IR sensor 130 is fed to the microprocessor 44 for -~
processing by an IR message routine 136 for detecting the data message. A vehicle sensor rou~ine 138 in microprocessor 44 processes signals from the vehicle ~ensor 50 for detecting an aircraft or other ~ehicles~ The IR
message routine 136 is implemen~ed with ~oftware within the microproce~sor 44 a3 shown in the flow chart of FI~. 15.
The vehicle ~en~or routine 138 is also Lmplemented with ~oftware within the microprocessor 44 as shown in the f~ow chart of FIG. 16. The output~ of the IR mes~age routine 136 and v~hicle sensor routine 138 are processed by the 2~

microprocessor 44 which send~ via the power line modem 54 the identified aircraft or vehicle and their position data over ~he edge light wiring 211n communication line~ to the central compu~er system 12 shown in FIG. 1 at the airport S v terminal or con~rol tower. The IR sensor 130 may be embodied with Model RY5BD01 IR sensor manufac~ured hy Sharp Electronics, of Paramus, New Jersey. The microprocesssr 44 may be embodied by the VLSI Neuron Chip, manufactured by Echelon Corporation, of Palo Alto, California~
Referring to ~IG. 15, a flow chart of ~he IR message routine 136 i8 ~hown which i~ a communication protocol continuously performed in the microprocessor 44 of the IR
receiver 128. After an IR signal is detected 150 the next action is tran~mitter acqui~ition or to acquire tLming 152.
The microprocessor 44 looks for the proper ~iming relationship between the received IR pulse~. If the correc~
on/off ratio exists, the microprocsssor 44 calculates ~he baud rate from the received tLming and waits to acquire the unique word 156 ~ig~ifying byte boundary and then checks for th~ cap~ure of the character co1ln~ 160 field byte. A:Eter the character count i~ known, the microprocessor 44 then capture~ each character in the vehicle ID 162 field and stores th~m away in a buffer. It then captures vehicle position 163 including lati~ude and longitude data. If the IR coded dat~ ~tream i8 disrup~ed before all ~he vehicle ID

,'~ . ' ' '~" '`','',.'` ' " ' ',` '' ` ` ` ' `

characters are received, the microproces~or 44 aboxts this recep~ion try and returns to the acquisition or I~ detected 150 sta~ After all characters have been received, the checksum 164 is calculated. If the checksum matches 166, then the message is validated and the vehicle ID relayed 168 to the central computer system 12. With this scheme the microprocessor 44 is implementing both the physical and a link layer of the OSI protocol by providing an error free channel.
Referring now to FIG. 16, flow chart is ~hown of the vehicle sensor rou~ine 138 software running on microprocessor 44. This software rou~ine 138 runs as a continuous loop. An internal timer i5 continuously checked for a time out condition ~timer = zero 170). As soon as the timer expires the analog value from ~ensor 50 is read ~ead Sensor ~alue 171) by the microprocessor 44 and ~he timer is reset to the poll_tLme 172 variable downloaded by the central co~puter system 12. This sensor value is compared again~t a predetermined detection threshold 173 and downloaded by the cen~ral computer system 12. If ~he sensor value is less than the detaction threshold, the microprocessor 44 set~ the network variable prelim_detect to ¦ the ~ALSE state 174. If the sensor value i3 greater than the detec~ion threshold the microprocessor 44 ~ets the natwork variable prelim dP~ect to the T~UE state 17~. If a 5~

-~ 211~

preliminary detection is declared, the program then checks to see what reporting mode 176 is in use. If all detections are required to be sent to the central computer syst~m 12, then this sensor value 180 is sent. If only those readings that are different from the previous reading by a predetermined delta and download by the central computer ~ystem 12, then ~his check is made 177. If the change is greater than the delta 177, ~he program check~ to se~ if it should confirm the detection 178 to eliminate any false alarms. If a confirmation is not required, then this sensor value 181 is sent. If in the confirmation mode, then the adjacent sensor~s 179 prelLminary network variable is checked. If the adjacent sensor has also detected the ob~ect, then the current sensor value 182 i5 sent.
This concludes the description of the preferred embodiment. However, many modifications and alterations will be obvious to one of ordinary skill in the art without departing from the ~pirit and scope of the inventive concept~ Thsrefore, it i~ intended ~hat the scop~ of this invention be limited only by the appended claLms.

Claims (40)

1. A vehicle identification system fox identifying aircraft and other vehicles on surface pathways including runways and other areas of an airport comprising:
means disposed on said aircraft and other vehicles for transmitting identification message data;
means disposed in each of a plurality of light assembly means on said airport for receiving and decoding said message data from said transmitting means;
means for providing power to each of said plurality of light assembly means;
means for processing said decoded identification message data generated by said receiving and decoding means in each of said plurality of light assembly means;
means for providing data communication between each of said light assembly means and said processing means; and said processing means comprises means for providing a graphic display of said airport comprising symbols representing said aircraft and other vehicles, each of said symbols having said identification message data displayed.

2. The vehicle identification system as recited in Claim 1 wherein said transmitting means comprises:
means for creating a unique message data which includes aircraft and flight identification; and infrared means coupled to said message creating means for transmitting a coded stream of said message data.

3. The vehicle identification system as recited in Claim 3 wherein:
said message data further includes position information.

4. The vehicle identification system as recited in Claim 1 wherein:
said receiving and decoding means comprises an infrared sensor.

5. The vehicle identification system as recited in Claim 3 wherein:
said receiving and decoding means comprises microprocessor means coupled to said infrared sensor for decoding said message data.

6. The vehicle identification system as recited in Claim 1 wherein:
said plurality of light assembly means being arranged in two parallel rows along runways and taxiways of said airport.

7. The vehicle identification system as recited in Claim 1 wherein said light assembly means comprises:
light means coupled to said lines of said power providing means for lighting said airport;
vehicle sensing means for detecting aircraft or other vehicles on said airport;
microprocessor means coupled to said receiving and decoding means, said light means, said vehicle sensing means and said data communication means for decoding said identification message data; and said data communication means being coupled to said microprocessor means and said lines of said power providing means.

8. The vehicle identification system as recited in Claim 1 wherein:
said symbols representing aircraft and other vehicles comprise icons having a shape indicating type of aircraft or vehicle.

9. The vehicle identification system as recited in Claim 1 wherein:
said processing means determines a location of said symbols on said graphic display of said airport in accordance with data received from said light assembly means.

10. A vehicle identification system for identifying aircraft and other vehicles on surface pathways including runways and other areas of an airport comprising:
means disposed on said aircraft and other vehicles for creating a unique message including aircraft and flight identification;
infrared means coupled to said message creating means for transmitting a coded stream of said message data;
infrared means disposed in each of a plurality of light assembly means on said airport for receiving said message data from said transmitting means;
microprocessor means coupled to said receiving means for decoding said message data;
means for providing power to each of said plurality of light assembly means, means for processing said decoded message data generated by said decoding means in each of said plurality of light assembly means;
means for providing data communication between each of said light assembly means and said processing means; and said processing means comprises means for providing a graphic display of said airport comprising symbols representing said aircraft and other vehicles, each of said symbols having said identification message data displayed.

11. The vehicle identification system as recited in Claim 10 wherein:
said message data further includes position information.

12. The vehicle identification system as recited in Claim 19 wherein:
said plurality of light assembly means being arranged in two parallel rows along runways and taxiways of said airport.

13. The vehicle identification system as recited in Claim 10 wherein said light assembly means comprises:
light means coupled to said lines of said power providing means for lighting said airport;
vehicle sensing means for detecting aircraft or other vehicles on said airport;
said microprocessor means coupled to said decoding means, said light means, said vehicle sensing means and said data communication means further processes a detection signal from said vehicle sensing means; and said data communication means being couple to said microprocessor means and said lines of said power providing means.

14. The vehicle identification system as recited in Claim 10 wherein:
said symbols representing aircraft and other vehicles comprise icons having a shape indicating type of aircraft or vehicle.

15. The vehicle identification system as recited in Claim 10 wherein:
said processing means determines a location of said symbols on said graphic display of said airport in accordance with data received from said light assembly means.

16. A vehicle identification system for surveillance and identification of aircraft and other vehicles on an airport comprising:
a plurality of light circuits on said airport, each of said light circuits comprises a plurality of light assembly means;
means for providing power to each of said plurality of light circuits and to each of said light assembly means;
means in each of said light assembly means for sensing ground traffic on said airport;
means disposed on said aircraft and other vehicles for transmitting identification message data;

means disposed in each of said light assembly means for receiving and decoding said message data from said transmitting means;
means for processing ground traffic data from said sensing means and decoded message data from each of said light assembly means for presentation on a graphic display of said airport;
means for providing data communication between each of said light assembly means and said processing means; and said processing means comprises means for providing such graphic display of said airport comprising symbols representing said ground traffic, each of said symbols having direction, velocity and said identification message data displayed.

17. The vehicle identification system as recited in Claim 16 wherein:
each of said light circuits being located along the edges of taxiways or runways on said airport.

18. The vehicle identification system as recited in Claim 16 wherein:
said sensing means comprises infrared detectors.

19. The vehicle identification system as recited in Claim 16 wherein said transmitting means comprises:

means for creating unique message data which includes aircraft and flight identification; and infrared means coupled to said message creating means for transmitting a coded stream of said message data.

20. The vehicle identification system as recited in Claim 19 wherein:
said message data further comprises position information.

21. The vehicle identification system as recited in Claim 16 wherein:
said receiving and decoding means comprises an infrared sensor.

22. The vehicle identification system as recited in Claim 21 wherein:
said receiving and decoding means comprises microprocessor means coupled to said infrared sensor for decoding said message data.

23. The vehicle identification system as recited in Claim 16 wherein:
said plurality of light assembly means of said light circuits being arranged in two parallel rows along runways and taxiways of said airport.

24. The vehicle identification system as recited in Claim 16 wherein said light assembly means comprises:
light means coupled to said lines of said power providing means for lighting said airport;
said ground traffic sensing means for detecting aircraft or other vehicles on said airport, microprocessor means coupled to said receiving and decoding means, said light means, said ground traffic sensing means and said data communication means for decoding said identification message data and processing a detection signal from said ground traffic sensing means; and said data communication means being coupled to said microprocessor means and said lines of said power providing means.

25. The vehicle identification system as recited in Claim 24 wherein:
said light assembly means further comprises a photocell means coupled to aid microprocessor means for detecting the light intensity of said light means.

26. The vehicle identification system as recited in Claim 24 wherein:
said light assembly means further comprises a strobe light coupled to said microprocessor means.

27. The vehicle identification system as recited in Claim 16 wherein:
said processing means comprises redundant computers for fault tolerance operation.

28. The vehicle identification system as recited in Claim 16 wherein:
said symbols representing said ground traffic comprise icons having a shape indicating type of aircraft or vehicle.

29. The vehicle identification system as recited in Claim 16 wherein:
said processing means determines a location of said symbols on said graphic display of said airport in accordance with said data receive from said light assembly means.

30. The vehicle identification system as recited in Claim 16 wherein:
said processing means determines a future path of said ground traffic based on a ground clearance command, said future path being shown on said graphic display.

31. The vehicle identification system as recited in Claim 16 wherein:

said processing means further comprises means for predicting an airport incursion.

32. The vehicle identification system as recited in Claim 16 wherein said power providing means comprises:
constant current power means for providing a separate line to each of said plurality of light circuits; and network bridge means coupled to said constant current power means for providing a communication channel to said processing means for each line of said constant current power means.

33. A method of providing a vehicle identification system for identifying aircraft and other vehicles on surface pathways including runways and other areas of an airport comprising the steps of:
transmitting identification message data with means disposed on said aircraft and other vehicles;
receiving and decoding said message data from said transmitting means with means disposed in each of a plurality of light assembly means on said airport;
providing power to each of said plurality of light assembly means;
processing said decoded identification message data generated by said receiving and decoding means in each of said plurality of light assembly means;

providing data communication on lines of said power providing means between each of said light assembly means and said processing means; and providing a graphic display of said airport with said processing means comprising symbols representing said aircraft and other vehicles, each of said symbols having said identification message data displayed.

34. The method as recited in Claim 33 wherein said step of transmitting identification message data comprises the steps of creating unique message data which includes aircraft and flight identification; and transmitting a coded stream of said message data with infrared means coupled to said message creating means.

35. The method as recited in Claim 34 wherein said step of transmitting message data further includes transmitting position information.

36. The method as recited in Claim 33 wherein said step of receiving and decoding said message data includes using an infrared sensor.

37. The method as recited in Claim 33 wherein said step of receiving and decoding said message data further comprises the step of coupling microprocessor means to said infrared sensor for decoding said message data.

38. The method as recited in Claim 33 wherein said step of receiving and decoding said message data with means disposed in said plurality of light assembly means further comprise the step of arranging said plurality of light assembly means in two parallel rows along runways and taxiways of said airport.

39. The method as recited in Claim 33 wherein said step of providing a graphic display comprising symbols representing aircraft and other vehicles further comprises the step of providing icons having a shape indicating type of aircraft or vehicle.

40. The method as recited in Claim 33 wherein said step of providing a graphic display comprises the step of determining a location of said symbols on said graphic display of said airport in accordance with data received from said light assembly means.