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`Automobile Navigation System Using
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`Beacon Information
`Junkoh Shims
`Takaharu Saito
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`Iiiroyuki Kanemitsu Yoshibumi ’I‘anaka
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`Toyota Motor Corporation
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`1200 Mishuku, Susono,Sizuoka,410-i‘i ,Japan
`
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`Tel 0559—97-212i Fax 0559—97—4419
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`Various items of
`Road and traffic information
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`road works,
`information,
`such as traffic conditions,
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`location of car parks and available spaces etc., are
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`transmitted from roadside beacons and may be selected
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`for display on the digital map.
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`Route
`guidance
`The shortest route
`planning and
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`between any two points can be calculated from stored
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`data and indicated on the digital map. If information
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`regarding delays on or impassibility of the indicated
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`route is received from beacons, an alternative route
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`is also displayed.
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`W "No-way cmmunication for
`personal messages and fleet management etc.
`is
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`nwv;dec via the communication service system.
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`‘
`Road‘
`adommis-
`tration
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`if
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`Individual
`communication
`center
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`Individual
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`communication
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`Information
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`beacon
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`,
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`‘
`" beacon
`i, individual] communication
`67:»;
`61\ Location
`\' be acon
`i
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`\I
`f
`i
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`Fig.1 Road and automobile communication system
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`W B
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`Beacons are of three types.
`eacons
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`The location beacon (LB)
`transmits signals
`(i)
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`identifying its location, i.e. secondary mesh code
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`(the map reference number of the 1/25,000 scale maps
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`issued by the Geographical Survey Institute), map
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`coordinates (x,y),
`link number (the number designated
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`In
`to the road ),
`link heading and beacon number.
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`addition other information of a constant nature may
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`be transmitted.
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`The information beaconiIB)
`transmits both
`(ii)
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`location signals and relays transient
`road and
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`traffic information received via a cable.
`(See Table
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`1 . )
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`(iii) The individual communication beacon (ICB) will
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`establish two—way radio communication with the
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`vehicle. The ICB itself will be connected to the
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`IN‘I‘ROIIJCI‘ION
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`becominc
`Driving an automobile today is
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`the road
`increasingly complex: The extension of
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`and highway network makes navigation more
`difficult,
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`while the tremendous increase in vehicles has in many
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`areas led to chronic traffic congestion. In order to
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`an on—board
`promote road safety and ease congestion,
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`navigational
`/ informational system based on roadside
`beacons will soon become indispensable. In this paper,
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`authors present a prototype vehicle system
`the
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`developed to operate in conjunction with the
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`communication network currently being established in
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`Japan as a cosoperative undertaking by the Public
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`Works Reseach Institute of
`the Ministry of
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`Construction and 25 private companies.
`The
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`system provides the driver with such essential
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`information as present
`location and traffic
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`conditions, plots optimum and alternative route to the
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`destination and enables
`limited two—way
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`communication to be made. Field testing of
`the
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`system is still being conducted. Here the
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`the first two tests are discussed.
`results of
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`OUTLINE OF RACS
`
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`communication service system center by cable. The
`
`ABSTRACT
`
`
`A navigation and communication system utilizing
`
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`roadside beacons
`is currently under
`
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`
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`development. This paper outlines the functions
`
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`
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`infrastructure of
`the system ( named
`and
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`RACS), describes the insvehicle equipment
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`TOYOTA and reports the results of
`developed by
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`field tests conducted in the Tokyo/ Yokohama
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`system is considered to have
`area.
`The
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`considerable potential
`for
`reducing and
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`improving road safety as well as being of great
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`benefit to drivers.
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`Road/Automobile Communication System (RACS)
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`is a network providing various services by means of
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`roadside devices and a vehicle mounted computer.
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`shows the concept of RACS, which is based on
`Fig.1
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`intermittent narrow band digital data communication
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`with limited range.
`'IWo-way individual cotmmnication
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`(i.e. private communication) for personal needs is
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`currently under
`development and has not yet been
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`subjected to field testing.
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`Main Functions
`
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`The main functions of
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`RACS are as follows.
`
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`The dead reckoning
`Detection of vehicle location
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`navigation device determines the present
`location in
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`real time using the vehicle directional and distance
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`sensors and
`corrects any error when a signal
`is
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`
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`received from a roadside beacon. The location is
`
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`
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`continuously indicated on the digital road map display.
`
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`GH2789-6/89ION0-0139501.00 © 1989 IEEE
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`Page 1 of 7
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`Unified Patents Exhibit 1011
`
`

`

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`Receiver
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`RSZ32C
`
`
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`Processing Unit
`
`(PC9801VM21)
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`|
` Touch-
`Sensitive
`
`Sensor
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`suitCh
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`Wheel
`Revolution
`Sensor
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`ESC ECU
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`Fig.2 Block diagram of in—Vehicle systen
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`Map Display and Data
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`CRT
`and memory unit The core of the man—machine
`
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`interface is the display unit. Ideally the CRT should
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`be as large as possible to facilitate use, but a
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`limit is imposed by the available space. As viewing
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`angle is also an important consideration, the test
`car made use of a 6 inch CRT mounted in the center of
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`the dash board (see Fig.3). In the prototype system,
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`an IC memory (ROM) was used to store map data since
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`the field test area is reasonably small. For
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`commercial systems, a CD—ROM such as used in the
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`ELECTRO MULTIVISION system would appear to be the
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`most promising media for data storage. Specifications
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`of the CRT and memory device are given in Table 3.
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`Fig. 3 Test car
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`Digital map data Stored map data were canpiled frcxn
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`the database prepared by PW'RI. As shown in Table 4,
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`four scales of map are available. The smaller scale
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`maps are provided to enable selection of the larger
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`scale maps (1:115000 ard 1:28500), which are used for
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`navigation. Fig.4 shows an example of the largest
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`scale navigation maps. The display changes
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`automatically when the vehicle moves
`from one
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`navigation map to another. Each navigation map
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`functions of the ICB may be expanded to include those
`of the IB.
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`In the first two field tests, inductive radio
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`was used for beacon transmissions. Cunently microwave
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`based communication is being tested. The
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`specifications of the inductive radio are given in
`Table 2.
`
`Traffic control and curmunication centers
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`The traffic control center, which is
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`administered by the relevant local road authority,
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`outputs road and traffic data based on the map and
`link numbers to the information beacons. The data is
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`updated at 5—minute intervals.
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`The communication service system center and
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`branches act as an interface for personal messages to
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`and from particular vehicles.
`Table 1 Road and traffic information
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`Congestion
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`Car antenna
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`Link No., Direction,
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`Congested lane, Cause,
`Level of congestion, etc.
`
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`Link No., Direction,
`Traffic accident
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`|_Cause, etc.
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`Link No., Direction, etc.
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`Roadwork
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`Road/lane regulation Link No., Direction,
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`Regulated lane,
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`Nature of regulation,
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`Cause, etc.
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`Tine needed to
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`travel link length
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`Link No. , Direction,
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`Time
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`Table 2 Inductive radio specifications
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`Transmission antenna Ferrite core coil
`
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`247. ZKHz
`Frequency
`Transmission power
`Very weak
`HSK
`Modulation
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`9600bps
`Transmission speed
`Transmission data
`IB: about 8000bits
`LB: 136bits.
`Ferrite core coil
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`In—vehicle equipment consists
`In—vehicle ggiflt
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`of a dead reckoning device, a ROM unit in which map
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`data are stored, CRT display, antenna and receiver.
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`The map database was prepared by the Public Works
`
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`
`
`Research Institute (PWRI) and ocmprises twelve files,
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`e.g. link file, node (or intersection) file, railway
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`file, facility location file etc. The data covers an
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`area of approximately 350szincluding southwestern
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`Tokyo, Kawasaki and northern Yokohama.
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`
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`DEVELOPMENT OF IN—VEIHICLE EDUIPMENTS
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`Fig.2 shows a block diagram of the prototype in—
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`vehicle system developed by the authors. The systan is
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`
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`composed of a dead reckoning device with geomagnetic
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`sensor, gyroscope and wheel revolution sensor; a 6
`inch CRT with touch—sensitive switches; a receiver; a
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`map data storage unit and a processing unit which
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`controls the system. A 16 bit personal computer (NEC
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`PC9801 VM21) was used as the processor.
`
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`The prototype system was installed in an '88
`
`
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`model TOYOTA CROWN as a sub—system of the multi—
`
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`purpobe display unit cal led EEECI‘RO MULTIVISION.“ ]
`
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`140
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`Page 2 of 7
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`Unified Patents Exhibit 1011
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`Page 2 of 7
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`Unified Patents Exhibit 1011
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`

`

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`O
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`O
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`O
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`O
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`l
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`O
`0
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`*
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`-
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`—
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`-—
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`—
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`'
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`-
`i
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`-
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`-
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`-
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`,.i i,
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`Names
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`Rail
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`ways
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`Land- buildings
`marks
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`beacons
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`Road names
`7" v r
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`Place names
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`Setting of initial location
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`Input of geomagnetic sensor data
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`Fig.4 Navigation map (1 :2850o)
`
`Detection of Vehicle Location
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`The dead reckoning device calculates the present
`position of the vehicle from directional and distance
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`data. The calculated position is displayed on the
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`navigation map. Accumulated errors in the dead
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`reckoning are corrected when the vehicle passes an LB
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`or IE. Consequently the navigational system operates
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`with a high degree of accuracy.
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`In order to minimize any
`Dial directional sensors
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`error in directional data, both a flux
`gate type
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`geomagnetic sensor and vibration type gyroscope are
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`used to calculate heading. A geomagnetic sensor is an
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`efficient means of detecting heading but its accuracy
`
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`is affected by regional differences in magnetic
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`declination and by interference caused by buildings,
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`tunnels, bridges,
`railways and large vehicles which
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`are travelling alongside. On
`the other hand,
`a
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`gyroscope, although unaffected by magnetic declination
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`and interference, accumulates directional errors
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`because it is subjected to drift as time passes.
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`the TOYOTA dead reckoning system utilizes data
`Hence,
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`from both sources and weights them appropriately.
`
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`Distance sensor Wheel sensors producing 48 pulses
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`per revolution were adopted as the distance sensor and
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`mounted on the non—driving (Le.
`front) wheels.
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`Calculation and displaLof location Directional and
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`distance data are continuously input to the control
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`unit, which computes
`the movement vector of the
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`vehicle at quarter—second intervals and outputs the
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`location in terms of navigation map co—
`present
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`ordinates every four intervals. Thus the position of
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`vehicle location mark on the CRT is updated every
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`second. The flowchart and calculation principle are
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`Input of gyroscope data
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`Y
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`End
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`Fig.5 Flowchart of dead reckoning
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`Error correction
`The control unit compares location
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`data received from a beacon with the calculated
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`location and corrects any errors. Because of the
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`intermittent communication and processing time,
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`141
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`i. r _
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`Page 3 of 7
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`Unified Patents Exhibit 1011
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`shown in Figs 5 and 6 respectively.
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`
`Table 4 Stored map contents
`i - ii 74
`iiiiiiiiii, iiiiiiiiii.
`Mr _
`,
`
`
`
`
`Scale
`Scale
`‘ Scale
`Scale
`
`
`
`
`
`
`
`12115,00
`1228,500
`£380,001 1:190,00
`Area dis Area dis Area dis Area dis
`
`
`
`
`
`
`
`
`
`
`
`
`played
`played
`played
`played
`
`
`
`45*37Km
`22*18Km
`14*11Km
`3.5*2.5K
`
`No. of
`No. of
`No. of
`No. of
`
`
`
`
`
`
`
`
`
`
`
`maps
`1
`maps
`4
`maps
`12 maps 182
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`Land
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`Lakes and marshes ‘
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`Rivers
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`Expressways
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`Toll roads
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`National roads
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`Prefectual roads
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`Municipal roads
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`Contents
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`overlaps neighbouring maps by i0% so that the driver
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`can easily follow the transition. In addition, a map
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`of the Tokyo Metropolitan Expressway System and a map
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`of car park locations are provided. All maps are
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`displayed in the north—up mode, i.e. north is to the
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`top of tie screen.
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`Table 3 Display and memory unit specifications
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`Type of display
`Size
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`Resolutions
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`Location
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`Type of memory
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`Memory capacity
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`CRT
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`6 inches
`320*240
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`Center of dashboard
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`10 memory
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`BHBytes
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`Page 3 of 7
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`Unified Patents Exhibit 1011
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`Fig.8 Display of congestion on Metropolitan
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`Expressway
`Shortest Route
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`The shortest route between any two given points
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`is calculated using data regarding link length and
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`flow direction at intersection ( e.g. no right—hand
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`turn etc.). This route is displayed on the navigation
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`maps in a flashing green color. A feature of the
`systen is that an alternative route is calculated and
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`displayed if signals from an IB advise of congestion
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`or closure of the planned route. when data are
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`available,
`the program will be extended to enable the
`quickest route to be calculated as well.
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`Input
`The driver inputs the departure point and
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`destination on the appropriate navigation maps, using
`the touch-sensitive switches on the screen to move
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`the cursor. He must also input whether or not toll
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`roads are to be used. The route is displayed from the
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`node of origin (i.e.
`the intersection closest to the
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`actual position of the vehicle, determined frun the
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`departure point coordinates and vehicle heading ) to
`the node of destination.
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`To minimize computation
`Algorithm of route search
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`time, a practical algorithm adequate for navigation
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`was developed.[2] Based on Nicolson's bidirectional
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`path finding algorithm,
`the method deals with an O—D
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`(origin—destination) pair problem and calculates an
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`approximate optimum. The main features are:
`The network for search is restricted to the
`(i)
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`elliptical area between 0 and D, the size of which
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`changes in proportion to the distance.
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`A node amount equality method, whereby the
`(ii)
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`number of nodes on the possible paths from O is
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`equal to the number on the possible paths from D, is
`used to establish the shortest route.
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`(iii) The principle of network degeneration is
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`applied. The initial search from O and D expands
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`along all classes of roads. However the network is
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`degenerated by eliminating any lower grade road if a
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`higher grade road may be fol lowed.
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`The revised origin method enables fast
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`calculation of a rerouting should the driver stray
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`from the planned route. If the vehicle passes an LB
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`or IE that is not on the designated route,
`the
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`shortest route from that point to D is calculated,
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`making use of the previously computed possible paths
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`from D. Figs 9 and 10 respectively show the concept
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`and efficacy of
`the developed algorithm, which
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`achieves a reduction in computation time of up to 90%
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`compared to the single source algorithm.
`Database for route search The in—vehicle database
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`for route search was compiled from the previously
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`FePnsition
`D=Distance Traveled
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`6=Heading
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`Fig. 6 Dead reckoning navigation amputation
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`beacon location data is accurate to within :t5m, but
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`this error is too small to effect the accuracy of the
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`navigation system.
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`Reception and Display of Transient Information
`Receiver
`and
`antenna
`The receiver utilizes a
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`digital circuit for modulation and demoiulation of the
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`signal and a control unit including an 8—bit micro—
`computer. The antenna is a ferrite core coil mounted
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`on the trunk lid (see Fig.7).
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`Fig.7 Inductive radio antenna
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`CRT display As stated above, information received
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`from an IB, such as congestion, road works and local
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`traffic regulations, are displayed on the CRT. Careful
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`consideration was given to the content and manner of
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`display.
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`The principal features are as follows:
`(i) When traffic information is received, words to
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`this effect are superimposed on the navigation map.
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`(ii) The driver may opt to view this information
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`either on the navigation map in use or on the Tokyo
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`Metropolitan Expressway.
`(See Figs 4 and 8.)
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`(iii) The information itself is expressed by a
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`flashing color along the affected part of the road:
`violet for congestion, black for road or lane closure,
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`red for an accident and yellow for road works.
`(iv)
`If the navigation map is showing the shortest
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`route (see below) and information regarding road or
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`lane closure or congestion of the route is received,
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`the driver may select a textual display giving
`details.
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`142
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`Page 4 of 7
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`Unified Patents Exhibit 1011
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`Page 4 of 7
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`Unified Patents Exhibit 1011
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`.
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`N “:0 13°”
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`BidireCtinal
`distance equality
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`Elliptical boundary
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`Rerouting area
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`D
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`D V“ we,
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`Single dlrecnnal
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`distance Equality
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`I
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`Node amount equality
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`(‘6 0
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`on the search (e.g. whether or not toll roads are to
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`be used, road restrictions on vehicle type,
`time—
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`based traffic regulations etc.).
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`(iii) The database is well matched with the stored
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`map data. The network for the field experiment area
`contains 2867 nodes and 4219 links.
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`Detour route search IB data concerning congestion is
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`expressed as a congestion factor (corresponding to
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`link flow rate). When such information is received,
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`the shortest route from the preceding node toDis
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`calculated (as above) in terms of total link cost
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`(distance x congestion factor) and displayed on the
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`CRT.
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`Display of Roadside Information
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`example of car park information. Space availability,
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`Roadside information obtained from an IE may be
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`selected for displayed on the CRT. Fig.ii shows an
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`charge and opening hours are displayed.
`ROAD TEST RESULTS AND EVALUATION
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`The road test area is shown in Fig.12. A total
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`major roads in this area.
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` of 93 beacons including two IBs were installed along
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`Eerouting
`Network degeneration
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`Fig.9 Concept of route search algorithm
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`H
`DiJkstra
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`jgNicolson
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`............... "
`Node equality
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`Fig.11 Display of car park information
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`.nter-
`national
`Aironrt
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`Fig.12 Field experiment area [3]
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`Sec.
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`200*
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`.—
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`mE
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`.2
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`0 j
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`.ua
`3100%Q
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`e
`Elliptical
`NEWS 953
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`Route distance between U-D
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`Km
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`Fig.10 Comparison of computation times
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`mentioned digital map database and is characterised
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`as follows:
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`(i)
`The file volume is as small as possible.
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`(ii) The database can meet options of and limitations
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`143
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`Page 5 of 7
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`Unified Patents Exhibit 1011
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`Page 5 of 7
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`Unified Patents Exhibit 1011
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`

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`Navigation Accuragy
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`Map gibility
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`Tests were conducted along various courses and
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`the error in dead reckoning was recorded at each LB.
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`Fig.13 plots the relationship between navigation error
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`and distance between beacons. As may be seen,
`the
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`average accumulated error is approximately 4% of the
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`driving distance between beacons, which in the case of
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`the average beacon interval of SKm means that
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`positional error is 200m or less. In some instances
`the accumulated error was more than 7%. This is
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`thought to be because the gyroscope cannot compensate
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`for small deviations in ccmpass readings due to local
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`magnetic sources. However, the results suggest that
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`with more beacons, especially in the vicinity of local
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`nagnetic sources, accurate navigation will be possible
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`even with a simple device. Fig.14 shows
`the
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`differences between car headings as calculated by dead
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`reckoning and link headings at beacons. Data such as
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`these can be used to further improve navigation
`accuracy.
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`7% error rate
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`4% error rate
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`Locationerror
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`02 lo
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`6
`8 101214 1618 2022M ZéKm
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`Distance between beacons
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`Fig.13 Relationship between navigation error and
`distance interval
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`Incidence
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`21 error rate
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`Screen size, map scale and colors were judged to
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`be reasonable. To improve man—machine interface, it
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`is thought that functions such as map scroll, map
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`rotation‘ (to permit heading up mode) and zoom
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`capability should be examined.
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`Information Data Reception and Content
`Data from the IBs were received without error.
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`It should perhaps be pointed out that because of the
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`inductive radio used in these tests, transmission
`rate is rather slow and the vehicle must be within
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`range of the IB for approximately one second to
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`receive total information. For this reason, the IBs
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`were located at toll booths. Further development of
`RACS will concentrate on microwave transmission to
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`enable data to be received while travelling.
`Because the road/traffic information was
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`detailed and was updated every five minutes, it was
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`felt that this information is very helpful for city
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`driving. Furthermore the visual display enable the
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`driver to quickly discern whether the information is
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`relevant or not. However, a speech mode system
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`capable of replay would also be beneficial in many
`circumstances.
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`Route Search
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`the route search were most
`The results of
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`encouraging.
`In most cases,
`the indicated route
`coincided with the route which the test drivers
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`selected either fran local knowledge or from printed
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`sheet maps, and sometimes drivers conversant with the
`test area were made aware of a better alternative to
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`the route that they would have chosen. The route
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`search function is therefore judged to be a
`considerable aid to drivers who are in an unfamiliar
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`area. Initial calculation of the shortest route took
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`about 20 seconds on average. For practical purposes,
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`faster algorithms must be developed so that this time
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`can be reduced to around five seconds. Because of the
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`time needed to apply the congestion factors to the
`calculation of
`link costs, computation of an
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`alternative route generally required 90 seconds,
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`which was far from practical as the driver often had
`to make a decision at an intersection before the
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`calculated alternative was available. Also, as
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`previously mentioned, search of the quickest route
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`will probably prove-of greater value. Thus for future
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`systems,
`improved software and hardware must be
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`developed and the database must be revised. Further
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`consideration should also be paid to the manner of
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`presentation. For example, aural guidance in addition
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`to the visual display would probably be welcomed by
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`many drivers.
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`CONCLUSIONS
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`Road/Automobile Communication System (RACS) is
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`being developed by private corporations in
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`conjunction with the Public Works Research Institute.
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`The system is based on roadside beacons which
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`transmit information to passing vehicles.
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`Field testing of the in—vehicle systan developed
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`by TOYOTA indicates that the navigation and route
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`search functions are of great benefit to drivers in
`an unfamiliar area. However, route search calculation
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`time must be reduced, especially in the _case of route
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`revision in response to incoming data. In the present
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`system nan—machine interface is aocanplished visually
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`desirable. It will therefore be necessary to develop
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`a system whereby information can be imparted by a
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`synthesized voice.
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`To increase data transmission speed and to enable two—
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`way communication to be established,
`a microwave
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`transmission system is currently under development and
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`is scheduled for testing in the near future.
`ACI‘WOWLWTS
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`The development in this paper was carried out
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`in the project "Road/Autunobile Communication System",
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`under a grant from the Public Works Research Institute
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`of the Ministry of Construction. The authors thank
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`persons concerned to promote the project and the
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`public demonstration. The authors also wish to fully
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`acknowledge to H. Tsuji of Toyota Central R&D Labs.
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`and A. Uzu of Toyota Motor Corporation for their
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`support to deVelop the in—vehicle navigation system
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`and for the discussions on the project.
`REFERENCES
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`"Toyota Electro Multivision"
`‘I] Y. Shoji et al.,
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`SAE880220,1988,pp.33—38.
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`"A Fast Shortest Path Method for
`2] H. Tsuji et al.,
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`In—vehicle Navigation System"
`The
`5th World
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`Conference of Transport Research (wCI'R), Yokohama,
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`Japan ,1989.
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` 5] H. Okamoto et al.,
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`"Experimental Study on
`3] S. Takaba et al.,
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`Road/Automobile Communication System in Japan"
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`The 78th International
`Symposium on Automobile
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`Technology & Automation (ISATA)
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`"Digital Map on CD (Called CD
`Ishikawa et al.,
`4] K.
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`Information)“ SAE‘380221,'|988, p.39—44.
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`"An Overview of AMTICS”
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`on Transportation
`Intematiorial Congress
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`Electronics Proceedings,1988,pp.219—228.
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