NAVIGATION: Journal of The Institute ofNauigation
`Vol. 34, No. 3, Fall 1987
`Printed in USA.
`
`The Evolving Roles of Vehicular
`Navigation
`
`ROBERT L. FRENCH
`
`R. L. French and Associates, Fort Worth. Texas
`Received June 1987
`
`ABSTRACT
`
`This paper examines existing and potential applications ofnavigation technology
`to motor vehicles that operate primarily upon streets and highways. Applications
`are described and representative systems approaches are outlined in three broad
`categories; driver information, traffic management, and fleet management. Driver
`information systems include those that develop and present navigation information
`in various forms to aid the driver in reaching the desired destination. The traffic
`management category includes navigation systems that consider real-time traffic
`conditions in determining optimum routes and, consequently, contribute to the
`overall improvement of traffic flow. Fleet management applications include auto-
`matic vehicle location monitoring systems (which do not necessarily provide nav-
`igation information to vehicle drivers) as well as systems which provide routing or
`step—by—step route guidance. The most comprehensive fleet management applica-
`tions of vehicular navigation may also include command and control functions.
`
`INTRODUCTION
`
`Motor vehicle navigation has traditionally been accomplished by reference
`to external road signs and landmarks while traveling over routes constrained
`(unlike sea, air and space navigation) to finite networks of streets and roads.
`Commonly used in-vehicle navigation aids have essentially been limited to
`road maps, the odometer, and an occasional magnetic compass.1 Except for a
`brief flirtation with mechanical route guides starting around 1910,2 automobile
`navigation received little attention until the late 19605, when the Federal
`Highway Administration’s short-lived Electronic Route Guidance System (ERGS)
`project3 presaged a wave of research on similar proximity-beacon route guid-
`ance and information systems which spread to Japan and Europe during the
`1970’s.4 The 1980s have brought extensive development work on a new gen-
`eration of automobile navigation systems based upon dead reckoning, radio
`location and map matching, in addition to further development of proximity-
`beacon systems.5
`Advances in microelectronics, computer, space, and cartographic technolo-
`gies permit the development of vehicular navigation systems with unprece-
`dented capabilities. Figure 1 shows improvements in position accuracy achieved
`by radio location as compiled by Luse and Malla.6 Although not strictly com-
`parable because their accuracies are expressed relative to digitized maps rather
`than absolute location, the accuracies of ARCS and Etak dead reckoning aug-
`
`212
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`mented by map matching are included in Figure 1.7:8 While each of the accuracy
`values plotted in Figure 1 is subject to qualifications and exceptions, the overall
`trend is inescapable—we are entering an era in which vehicle location may be
`pin-pointed to individual streets and intersections.
`The navigation technologies available, or that are in the process of becoming
`available, support the development of vehicular systems for performing such a
`Wide variety of useful functions that the taxonomy of systems applications is
`not yet well established. However, the following broad categories provide a
`useful framework for examining some of the more important functional roles
`that are evolving, and for outlining examples of various systems approaches to
`vehicular navigation that are applicable to these roles.
`
`10000
`
`-_ CELESTIAL
`
`1000
`
`100
`
`10
`
`
`
`
`
`POSITIONACCURACY(meters)
`
`TRANSIT
`NNSS .
`
`--O-- RADIO LOCATION
`
`A MAP MATCHING
`
`
`
`1940
`
`1960
`
`YEAR
`
`1960
`
`2000
`
`Fig. 1 —Improvements in Position Accuracy.
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`DRIVER INFORMATION
`
`This category includes systems that develop and present to the driver various
`forms of navigation information useful in determining how to reach the desired
`destination. This may range from minimal information regarding the direction
`and line-of-sight distance to a specified destination, to real—time step-by-step
`route guidance instructions for reaching the destination. Intermediate levels
`of driver information systems may provide a complete plan and position indi-
`cation on a map display.
`Use of conventional road maps as a navigation aid requires several cumber-
`some and error-prone steps. Users must first identify their location and desti-
`nation on the map. A reasonable route between these two points must then be
`determined by inspection. Finally, the user must be able to successfully follow
`the planned route. Research indicates that 64 percent of the general population
`has difficulty in reading maps, and that navigation aids that replace conven-
`tional map reading and following processes by voice instructions are the most
`effective.9
`
`The wide range of vehicular navigation aids in the driver information cate-
`gory is illustrated by the following systems, some of which are already on the
`market.
`
`VDO City Pilot
`
`A dead-reckoning system called “City Pilot” is currently on the European
`market. Developed by VDO Adolf Schindling AG, it uses an earth magnetic
`field sensor and an odometer distance sensor.10 Like virtually all other dead-
`reckoning processes included in vehicular navigation systems, City Pilot inte-
`grates measured increments of travel with corresponding heading measure-
`ments to continuosly estimate the vehicle’s coordinates relative to an initial
`location.
`
`Prior to a journey, the driver uses a light pen to read bar—coded starting and
`destination coordinates on a special map. Using the sensor inputs and desti-
`nation coordinates, a microcomputer continuously calculates and displays the
`direction and line-of-sight distance to the destination. LCD arrows show the
`driver which general direction to take, while numerals indicate the remaining
`distance. Test results reveal that drivers using the system reach their desti-
`nations with an accuracy of 97 percent (i.e., within 3 percent of the distance
`traveled).
`
`Etak NavigatorTM
`
`The first commercially available automobile navigation system based on dead
`reckoning augmented by map matching is the Etak NavigatorTM now marketed
`in California. Map matching applies artificial-intelligence pattern recognition
`concepts to correlate measured vehicle paths with road maps which are digitized
`and stored in computer memory. With map matching, sensed mathematical
`features of the vehicle path are continuously associated with those of roads
`encoded in a map data base, just as a driver associates observed landmarks and
`road features with those depicted on a paper map to recognize position.5 Dead—
`reckoning errors are thus removed by automatic reinitialization at each turn.
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`French: Vehicular Navigation
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`The Etak system uses a flux-gate magnetic compass as well as differential
`odometer for dead reckoning. The differential odometer is essentially a pair of
`odometers, one each for the wheels at opposite ends of a common axle. When
`the vehicle changes heading, the outer wheel travels farther than the inner
`wheel by an amount (AD) that is equal to the product of the change in heading
`(Ad)) and the vehicle’s width (W): AD = WAd). Thus, by real-time analysis of
`the differential travel of opposite wheels, a vehicle’s path and heading relative
`to its starting point may be computed using algorithms based on the above
`equation.2
`The Etak system uses 3.5-MByte tape cassettes to store digital map data
`approximately equivalent to two paper street maps.8 The vehicle’s location
`relative to its surroundings is continuously displayed on a monochrome CRT
`map presentation which may be zoomed to different scales. A fixed symbol
`below the center of the CRT represents the vehicle position, and points to the
`top of the display indicating vehicle heading as indicated in Figure 2. As the
`vehicle is driven, the map rotates and shifts about the vehicle symbol to main-
`tain an orientation corresponding with the driver’s view through the wind-
`shield.
`
`A simplified push button arrangement allows destinations to be input by
`street number and name, or by street name and nearby cross street. The current
`destination is shown on the Etak screen as a flashing star. When off the
`
`
`
`Fig, 2—Etak Navigator” Display.
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`displayed map scale, the direction and distance to the destination is shown on
`the margin of the screen. Up to 16 destinations may be stored for sorting and
`quick recall.
`
`Blaupunkt EVA
`
`Bosch-Blaupunkt has developed a map-matching system called “EVA” which
`uses a differential odometer and includes route-search software to generate an
`optimum route to input destinations.11 Turns at intersections, lane changes,
`etc. are specified on an LCD in the form of simplified diagrams which show
`lane boundaries and displays arrows to indicate the path to be taken. Synthe-
`sized voice capability is included, and is used to confirm destination entries as
`well as to articulate turn-by—turn, real-time route guidance instructions.
`The first version of EVA (Figure 3), which has been tested and demonstrated
`since 1983, has a digital map of the test site (the small city of Hildesheim in
`West Germany) stored in EPROM with a capacity of approximately 109 KBytes.
`Like the Etak system and most others that use digital maps, the EVA map
`represents streets by straight segments that connect node points whose coor-
`dinates correspond to intersections. Intermediate nodes, known as shape points,
`are used to approximate street curvature between intersections. Since optimum
`routes are determined by algorithm, the EVA map data must also define traffic
`attributes such as one-way streets and turn restrictions.
`An enhanced version of EVA which is slated for testing late this year has
`been designed to use CD-ROM for storing map data. Since CD-ROM has a
`storage capacity of approximately 550 MBytes, one compact disc could accom—
`modate all streets and roads in West Germany plus extensive “yellow pages”
`and other directory features.
`
`Navstar GPS
`
`The Navstar Global Positioning System (GPS), which is being implemented
`by the Department of Defense, has been investigated as a basis for automobile
`navigation systems by General Motors,12 and was the basis for CLASS, the
`Chrysler Laser Atlas and Satellite System, a concept displayed at the 1984
`World’s Fair in New Orleans.13 CLASS included a nationwide set of maps stored
`
`wice outpyl
`Mass memory Io: caty map
`
`
`Inpul o! doshnaloon
`
`
`
`Display
`
`
`Roule scotch
`Wheel sensors tor
`
`Location
`locating Signals
`Nevin-lion
`
`Fig. 3—Blaupunkt EVA System Concept.
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`Vol. 34, No. 3
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`French: Vehicular Navigation
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`in image form on a video disc, and software for automatically selecting and
`displaying on a color CRT the map area incorporating the vehicle’s current
`location. Like most proposed automotive navigation systems based on Navstar
`GPS, CLASS shows vehicle location by positioning a curser on the map display.
`Still in the implementation stage, the Navstar GPS system will be completed
`in the early 1990s when the last of 18 satellites are orbited. The 18 satellites
`are being spaced in 12-hour orbits such that at least four will always be in
`range from any point on earth. Using precisely timed signals from four satel-
`lites, the GPS receiver’s computer automatically solves a system of four
`simultaneous equations for its three position coordinates and a time bias signal
`for synchronizing the receiver’s quartz clock with the satellites’ precise atomic
`clocks.
`
`Although GPS has great potential accuracy and will provide continuous
`coverage when the satellite constellation is complete, auxiliary dead reckoning
`is required in automobile applications to compensate for signal aberrations due
`to shadowing by buildings, bridges, foliage, etc. A recent evaluation of GPS for
`land vehicles notes that, because of differing ellipsoidal reference systems, the
`task of melding GPS location with local maps is formidable.” Hence map-
`matching technologies may be useful with GPS as well as with dead reckoning.
`
`TRAFFIC MANAG EMENT
`
`The potential of on-board route guidance systems for improved traffic man-
`agement has long been recognized and, in fact, was the major thrust behind
`the Federal Highway Administration’s ERGS project of the late 19605.3 Although
`the pursuit of this objective has, until recently, been essentially dormant in the
`United States, it has been the basis for extensive public sector involvement in
`the development of navigation and route guidance systems in Japan and Europe.
`A recent economic assessment” of the potential for improved motorist route-
`following in the United States found that recoverable navigation waste amounts
`to 6.4 percent of all distance traveled by non-commercial vehicles and 12.0
`percent of all time spent in such travel. The annual cost to individuals and to
`society of this excess travel was estimated at $45.7 billion considering only
`vehicle operating and accident costs and the value of time. It follows that if a
`significant fraction of vehicles were outfitted with effective navigation aids,
`their diminished demands on roadway capacity would contribute to improved
`traffic conditions as well as great economic savings.
`Automobile navigation systems with routing or guidance functions are even
`more effective if current information on traffic conditions is available for con-
`
`sideration in routing. It is estimated that the potential savings by eliminating
`navigation wastes increases to $73.6 billion annually if real-time traffic infor-
`mation is available to on-board route guidance systems.16 Traffic flow would
`also be enhanced by route guidance systems that responded dynamically to
`current conditions to avoid congested areas, thus contributing to balanced
`traffic management.
`
`Philips CARIN
`
`Self—contained automobile navigation route guidance systems such as the
`EVA system outlined above may be adapted to receive real-time traffic infor-
`
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`mation over a suitable data communication link, and to take this information
`into account in providing guidance over routes optimized for minimal travel
`time under the prevailing traffic conditions. This concept is included by Philips
`in the design of CARIN, another automobile navigation and information system
`under development in Europe. Figure 4 shows a functional block diagram of
`CARIN.17
`
`The vehicle location subsystem of the CARIN test and demonstration system
`employs dead reckoning augmented by map matching, and future versions may
`include a GPS receiver as well. CARIN is the first system to use the compact
`disc (CD-ROM) for storage of digital map data. The system includes a route-
`search algorithm and provides step-by-step route guidance. A color CRT map
`display shows vehicle location relative to the surroundings, and synthesized
`voice instructions prompt the driver when operating in the route guidance
`mode.
`
`The CARIN car radio data link for traffic information has not been imple—
`mented because standards have not yet been set and the infrastructure for
`collecting and communicating traffic data is not fully in place. However, several
`different approaches for communicating traffic data are being considered in
`Europe.18 One approach, called RDS (radio data system), uses a sub-carrier
`(SCA) to piggyback traffic data on commerical FM broadcast transmissions.
`Such data could be detected by a special feature or attachment to the regular
`
`
`
` VEHICLE
`COMPACT
`LOCATOR
`DISC
`
`
` USUAL
`
` INFORHATION
`AUTOMOTIVE
`PROCESSOR
`
`FUNCTIONS
`
`
`
`
`
`USER INTERFACE
`
`DRIVER
`
`
`
`Fig. 4—CARIN Functional Block Diagram.
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`French: Vehicular Navigation
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`219
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`car radio and relayed to the navigation system. A precedent for this approach
`is Blaupunkt’s ARI system which receives voice traffic bulletins over an FM
`sub-carrier.19
`
`U.K. Autoguide
`
`In 1986, the U.K. Department of Transport proposed Autoguide (Figure 5),
`a multi-step project starting with an early demonstration of interactive route
`guidance and traffic management in London.2° Autoguide is a system for help—
`ing drivers find their way through the primary road network. A route computer
`is mounted in the vehicle and the driver enters the destination. Either visually
`or using synthesized speech, the computer then gives easy-to—follow instructions
`during the journey.
`Unlike CARIN, which has autonomous navigation and route guidance func-
`tions that are useful even in the absence of infrastructure support, Autoguide
`operation is dependent upon proximity beacons. The Autoguide computer com-
`municates with beacons, near main junctions, which act as “electronic sign-
`posts.” As an equipped vehicle passes each beacon, it transmits its destination,
`type and, possibly, preference for the type of route—the driver might want the
`quickest, or the shortest (the two are not necessarily the same), or have some
`other requirement such as “no motorways.” The beacon immediately transmits
`back to the vehicle details of the directions to be taken at the junction, and the
`route computer translates them into simple instructions for the driver.
`The Autoguide beacons are themselves small computers which store the
`electronic signpost information as a form of list, which is frequently updated
`by a larger computer in a control center. The control center continuously
`recalculates routes on the basis of current traffic conditions. Drivers can there-
`
`fore be given guidance based on up—to-date information about the entire urban
`area.
`
`While it is to be implemented with microelectronics and other advanced
`technologies that were not available 20 years ago, the Autoguide concept is
`Virtually identical to that of the Federal Highway Administration’s ERGS
`project of the late 19605.3
`
`EFLG. ALI-SCOUT
`
`A major new development in route guidance systems is ALI-SCOUT, a joint
`project of the Federal Republic of Germany, Siemens, Volkswagen, Blaupunkt
`and others.21 ALI-SCOUT combines certain characteristics of both CARIN and
`
`Autoguide in that, while dependent upon proximity beacons like Autoguide,
`the in-vehicle equipment includes dead reckoning and map matching features
`that permit autonomous navigation between beacons which, consequently, may
`be spaced at greater intervals.
`The ALI-SCOUT vehicular equipment receives approximately 8 KBytes of
`area road network data and recommended route data when passing strategi-
`cally-located infrared beacons. Simplified graphic driving directions to the
`input destination are presented in real time on a dashboard LCD. The operating
`principle and major system elements of ALI-SCOUT are illustrated by Figure 6.
`An unusual feature of ALI-SCOUT is that, as an equipped vehicle passed
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`ROAD SIDE
`EQUIPMENT
`
`ELECTRONIC
`
`o Dunn-Hon
`
`0 Vlhldelype
`
`SIGNPOST
`
`Fig. 5—A utoguide System Concept.
`
`each beacon, it transmits to the beacon stored data on its travel history since
`passing the last beacon. The equipped automobiles thus serve, in effect, as their
`own traffic sensors. ALI-SCOUT will be subjected to large-scale field testing in
`West Berlin starting in 1988. Beacons will be installed at 20 percent of the
`traffic lights, and 1000 automobiles will be equipped.
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`
`P:
`
`N:
`0:
`
`Position-finding device with
`magnetic field sensor MS and
`wheel puleer WP
`Navigation device
`Operation board with keyboard
`direction indicator and
`destination store 05
`MT: Measuring device
`tar travelling time
`Infrared transmitter
`Infrared receiver
`
`IT:
`IR:
`
`
`
`
`
`
`
`
`Travel time
`per road section
`
`
`
`Traffic-dependent
`route
`recommendations
`
`TGC: Tralfic guidance
`computer
`TC: Traffic light
`controller
`B E: Beacon electronic:
`BR:
`IR beacon receiver
`ET:
`llt beacon transmitter
`
`
`
`Fig. 6—ALI-SCOUT Operating Principle.
`
`CALTRANS Initiative
`
`Between 1970, when Congress failed to appropriate funds for continuation
`of the ERGS project, and 1987, US. public sector research on vehicular route
`guidance was essentially limited to a few paper studies},15 Although a number
`of private organizations have pursued the development of vehicular navigation
`systems that can operate autonomously, public sector involvement is required
`for dynamic traffic-responsive route guidance systems because of its responsi-
`bilities in traffic management and the collection of traffic data.
`Due largely to a CALTRANS conference on “Technology Options for Highway
`Transportation Operations” held in Sacramento, California, October 28—31,
`198622 which served as a catalyst, a coalition including the FHWA, CALTRANS
`and the transportation departments of other key states, and private industry,
`is now actively developing a plan for demonstrating the traffic management
`advantages of providing real-time traffic information to on-board navigation
`systems. This planning effort is still in the formative stages, and is expected to
`lead to an initial procurement action in October 1987 to select a systems
`integrator for the demonstration.
`Concepts under consideration for the demonstration center on the Etak Nav-
`igator”, the only automobile navigation system already available in the US.
`While the Etak system does not provide route guidance per se, software modi-
`fications would permit the system to superimpose real-time traffic information
`on the map display (see Figure 2) in a manner such that the driver could take
`it into account in route planning. Traffic data already collected by conventional
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`means for traffic signal control would be augmented and communicated to
`Etak-equipped vehicles via cellular telephone. Consideration is also being given
`to communicating the recent travel experience of some Etak-equipped vehicles
`to the traffic data center for additional information on current traffic conditions.
`
`FLEET MANAGEMENT
`
`Various systems for remotely monitoring the location and status of individual
`vehicles have been used as fleet management tools for years, particularly for
`transit bus schedule control and police car dispatching.23 The location infor-
`mation thus developed aboard fleet vehicles is almost invariably communicated
`via radio link to the dispatch center rather than presented to the driver as in
`the case of a vehicular navigation system.
`In the past, such systems have primarily used electronic signposts, dead
`reckoning or, especially in recent years, Loran-C. Now, several technologies
`offer fleet managers wider choices for obtaining continuous updated position
`readings for their vehicles, whether locally or anywhere in the country.24
`The technologies employed for automatic vehicle location (AVL) monitoring
`and for vehicular navigation tend to overlap, and some integrated systems
`which serve both functions are now beginning to appear. In addition, valuable
`fleet management functions may be performed by systems which have navi-
`gation features alone, or navigation in conjunction with command and control
`features, regardless of whether vehicle location information is automatically
`communicated to a central dispatch station.
`
`Loran-C AVL
`
`Although Loran—C has been used for decades for marine and aircraft navi-
`gation, and has often been considered as a possible basis for AVL systems,23
`dependable cost-effective Loran—C receivers designed specifically for the hostile
`electromagnetic environment encountered by land vehicles have become avail—
`able only in the last few yearst’z‘a’z7
`Loran-C AVL systems, unlike the obsolescent electronic signpost approach
`to AVL, have the advantage of not requiring infrastructure support other than
`the existing Loran-C transmitter chains operated by the US. Coast Guard
`which is now installing mid-continent chains to complete nationwide coverage.
`Each chain of 3 to 5 stations transmits time—synchronized signals at approxi-
`mately 100 KHz in the form of groups of pulses. The time difference of arrival
`of pulses between the master and each of the secondary stations describes a
`line of position. A Loran-C receiver measures the time difference of two or more
`master-secondary pairs, and the intersection of the described lines of position
`defines the receiver’s location. In most cases the time differences are transmit-
`
`ted from the vehicle to the monitoring dispatch office for conversion to location
`coordinates which, in turn, are used to show vehicle location on a CRT map
`display. Most systems include driver—operated switches for reporting status as
`well as location.
`
`Land mobile radios, which many fleet operaters already have installed for
`voice communications, are often fitted with modems to transmit vehicle location
`data to the dispatch office. However, at least one Loran-C based AVL system
`uses cellular telephone.27
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`With the availability of high-performance Loran-C receivers at moderate
`cost, the types and number of AVL installations have proliferated. In addition
`to traditional transit bus and police fleet monitoring, Loran-C AVL applications
`now include public utilities, waste management, security, and general trucking
`applications. Although Loran-C has not yet been seriously pursued as a basis
`for automobile navigation, the experience base being acquired through AVL,
`along with the completion of nationwide coverage in 1989, make it probable
`that Loran-C automobile navigation systems will also be developed Within the
`next few years. However, like Navstar GPS systems, dead-reckoning backup
`and possibly map-matching augmentation may be required.
`
`Geostar Positioning
`
`The Geostar Satellite System will be the world’s first commercial network
`that provides fleet managers with nationwide radio location and two-way dig-
`ital communications from the same set of user equipment.2g Major system
`elements include a control and central processing center (ground station), two
`or more geosynchronous relay satellites, and user transceivers. Except for very
`large-scale fleets which might justify operating their own ground stations,
`Geostar AVL operates as a service requiring additional communications links
`between the control and central processing center and the dispatch centers of
`individual user fleets.
`
`When complete, two Geostar satellites will be used in a triangulation process
`to determine vehicle location. The process starts at the base station with an
`interrogation code that addresses the message to one or a group of vehicles,
`plus a digital notation indicating the time the signal was sent. One satellite
`relays the signal to the vehicle’s transceiver where it is retransmitted to both
`satellites which, in turn, relay it back to the ground station. Recognizing its
`original time notation, the base-station computer calculates the time it took
`the vehicle’s retransmission to reach the separate satellites. Since the satellites’
`positions are known, the computer can determine the vehicle’s distance from
`each and pinpoint the location. The computer then uses digital map data to
`translate position coordinates into a real-world location and transmits it to the
`fleet terminal.
`Full-scale Geostar service is scheduled for 1989. In the meantime, location
`service is provided by using a single Geostar satellite to relay Loran-C deter-
`mined vehicle locations to the ground station.24
`
`Etak Dispatch System
`
`The Etak NavigatorTM described above serves as the location sensor of an
`AVL and dispatch management system that has been introduced by Etak, Inc.29
`As shown schematically in Figure 7, a modem is used to interface the onboard
`navigation system to a conventional land mobile radio for data communications
`with the dispatch center.
`Reports from the navigation system that are sent to the dispatch center
`consist of the vehicle’s latitude, longitude, heading, speed, status, and other
`pertinent data for special applications. Heading is necessary to orient the
`vehicle symbol on the dispatcher’s map display, and speed is useful for man-
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`MANAGER
`
`BASE
`STAl'lUN
`
`DISPAYCH
`
`Fig. 7—Etak AVL System.
`
`agement purposes. Status codes may be selected by the driver through button
`entry.
`The Etak dispatch system includes an interactive map display workstation
`designed to enable dispatchers to monitor location and dispatch vehicles. The
`workstation comprises an IBM PC/AT (or equivalent) with keyboard, mouse,
`full color monitor and local area network interface. Resident on disk at each
`
`workstation is a map database corresponding to the digital maps used by the
`on-board navigation system. The map is displayed on the monitor with different
`colors representing different street categories (e.g. residential, arterial, free-
`way). Items from several categories of interest may be superimposed on the
`map display, including vehicles, landmarks and destinations.
`Each vehicle appears as a color coded symbol on the map display. The color
`and symbol shape may be used to designate type of vehicle (e.g. ambulance,
`hook and ladder, police, etc.), and status (e.g. available, enroute, emergency).
`The position and orientation of the symbol indicates last reported position and
`heading. Each vehicle has associated with it an identification number, status,
`vehicle type, position, heading, speed, report time, driver name, and dispatch
`assignment, if active. Any one of these attributes may be used to label the
`vehicles on screen.
`
`In addition to conventional AVL and dispatch functions, the Etak dispatch
`management system may be used to communicate destinations directly to the
`on-board navigation system. Once received, the destination appears on the
`screen as a flashing star. Because of the heading-up format, the direction to
`the destination is immediately obvious. The distance to go and direction to the
`destination are also displayed at the top of the CRT screen so that if the driver
`selects a map scale which does not include the destination, positive orientation
`is maintained. The dispatcher may also send a message with each new desti-
`nation to instruct the driver on dispatch details.
`
`Routeware’“ ARCS
`
`A further extension offleet management applications of vehicular navigation
`systems is illustrated by the Automatic Route Control System (ARCS) which
`provided command and control functions in addition to real-time route guidance
`over programmed newspaper delivery routes.7 The routes were programmed on
`tape cartridges in the form of digital maps which included the location of each
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`individual street address. The route data tapes could be prepared from central
`computer files, or by driving a route with an equipped vehicle to “record” the
`route.
`
`ARCS pioneered the application of map matching to vehicular navigation.
`An on-board computer analyzed differential odometer signals, deduced the
`vehicle’s path and correlated it with the programmed path to maintain high
`accuracy, to identify locations for issuing route guidance instructions to the
`driver, and for prompting the throwing of newspapers to individual subscriber
`houses included on the route tapes. Route guidance was initially accomplished
`by automatically activating prerecorded voice messages as each turn was
`approached. A subsequent version used a plasma panel to display graphic
`instructions and explanatory text as shown in Figure 8.30
`This system was in daily revenue service during a one-year test by the Fort
`Worth Star Telegram in the 19703.31 While technically successful, and even
`marginally cost-effective in spite of the relatively expensive electronics at that
`time, ARCS’ patented technology was subsequently put on the shelf until labor
`and management were more receptive to highly automated forms of fleet man-
`agement. The author and a group of associates are currently developing an
`enhanced version of ARCS which will be applicable to a variety of fleet route
`operations.
`
`CONCLUSIONS
`
`The most fundamental task of a vehicular navigation system is to continu-
`ously maintain accurate track of the vehicle’s location. This may be accom-
`plished by a number of means, but practical systems require two or more
`navigation technologies for continuously effective operation. Dead reckoning
`appears as the common element in virtually every systems approach. Dead
`
`
`
`Fig. 8—ARCS Route Guidance Instruction.
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`reckoning is necessary to augment radio-location system