Abstract:
An efficient transmission of route information, especially also in remote areas for which a terminal unit has no detailed map or location reference list, is made possible by a terminal unit, a central traffic station and a process for the transmission of route information concerning a route of a vehicle in a traffic network between a central traffic station and a terminal unit in a vehicle. The route information concerns path points lying on the route, wherein a path point is defined at every location where it is recommended that the vehicle turns off from a road. The next road following in the driving direction of the route, the location of the path point, and the driving direction after the path point are designated in each instance in route information for a path point.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to a process for the transmission of route information concerning a route of a vehicle in a traffic network between a central traffic station and a terminal unit in a vehicle, a central traffic station, and a terminal unit. 
     2. Discussion of the Prior Art 
     A central traffic station can prepare traffic status reports, traffic forecasts and traffic navigation aids for a terminal unit from information obtained from stationary detectors in a traffic network and obtained from mobile detectors (in vehicles FCD) and transmitted to the central traffic station. For the transmission of obtained traffic information from a vehicle (via mobile radio, etc.) to a central traffic station as well as for the transmission of information about traffic status reports, traffic forecasts, traffic navigation aids, etc. from a central station (via mobile radio, etc) to a terminal unit, it is required to designate each location to which a piece of information refers. When there is an identical map in the terminal unit and in the central station, location referencing with respect to the map is possible; however, maps are constantly being updated because of new roads, changes in driving direction, detours, construction sites, etc., so that different map versions may exist in the terminal unit and in the central station. A problem in location referencing based exclusively on geographic longitude and latitude consists in the required allocation to a road in a map; in particular, for example, there may be no road at a measured location position of a terminal unit in the map in the central station or no road in the map terminal unit at a geographic location position in the map which is referenced by a central traffic station. The use of shared reference tables for locations in a traffic network is limited with respect to the degree of detail because of limited available storage capacity. Such processes are accordingly suitable only to a limited extent for the transmission of information within the framework of a navigation service which is also especially advisable in remote areas. 
     SUMMARY OF THE INVENTION 
     The object of the invention is a simple and efficient optimizing of the location referencing in the transmission of information between a terminal unit and a central traffic station. 
     The invention makes possible an efficient location referencing also in remote areas for which there may be no detailed map in the terminal unit and/or no reference table with code designations and locations assigned thereto in the traffic network. In this respect, the transmitted route information concerning the route of a vehicle in a traffic network is sufficient for identifying a route of a vehicle when transmitting route information to the vehicle as well as when transmitting route information to the central traffic station. The location of a possible turn of a vehicle is sufficiently defined by means of designating the next road following in the driving direction of the route and by designating the location of a path point; the continued forward movement direction of the vehicle is defined by sending the driving direction after the path point. For this purpose, a path point is defined wherever a vehicle has turned off or should turn off from a road. 
     According to a preferred embodiment of the invention, the transmitted route information indicates a route suggested by the central traffic station for the vehicle as a navigation aid, wherein the route information is transmitted to the vehicle from the central traffic station and wherein path points are defined wherever the central traffic station transmits a suggestion to the terminal unit in the vehicle that the vehicle should turn. This makes possible an efficient navigation aid for a vehicle without the need for the presence of a detailed map for remote areas, foreign territory, etc. or for location reference tables in the terminal unit in the vehicle. 
     According to a further embodiment of the invention, the route information describes a route which is traveled by a vehicle and concerning which the vehicle transmits information to the central traffic station (for interactive monitoring of navigation of the vehicle or for preparing traffic status reports or traffic forecasts); in so doing, the route information is transmitted from the terminal unit in the vehicle to the central traffic station. Path points are defined wherever the vehicle has turned off from a road. When this arrangement is used as a navigation aid, the name and, if necessary, the driving direction can be queried from the vehicle terminal unit to the central traffic station so as to be entered in the terminal unit by the user manually or acoustically for interactivity or for monitoring the path along which a navigated vehicle is driving. The direction can also be determined based on continuous GPS measurements. When using this arrangement for conveying information to the central traffic station about a path traveled by the vehicle for preparing traffic status reports or traffic forecasts, route information, especially a detection of the names of the roads being traveled, the locations of path points and the driving direction, is advisably detected in the terminal unit automatically; when determining position (e.g., from GPS), road names, locations of turnoff-path points, e.g., from a map in the terminal unit, and driving directions are automatically determined and sent as route information to the central traffic station. 
     There is advisably a digital map of the traffic network in the central station. 
     A route in the traffic network recommended by the central station to a terminal unit in a vehicle is calculated in the central station, e.g., by a route calculation program; in so doing, a digital map and/or traffic information, etc. can be included. 
     The communication between a central traffic station and a vehicle is advisably carried out by radio, especially mobile radio. The driving direction after a path point can be indicated and transmitted in the route information particularly as a compass point and/or as a turnoff direction (that is, left/right/straight/sharp left, etc.). 
     The process according to the invention can be implemented as a program in a central traffic station and in a terminal unit. 
     Further features and advantages of the invention are indicated in the following description of an embodiment with reference to the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a section from a traffic network; and 
     FIG. 2 shows an abstracted view of the section of the traffic network shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The traffic network shown as a section in FIG. 1 has the following roads:  1 =Kölner Strasse;  2 =Verdi-Strasse;  3 =Mozart-Strasse;  4 =Hinterer Waldweg;  5 =Beethoven-Strasse;  6 =Bachstrasse. Also shown is a compass  7   a  which shows that the cardinal point in FIG. 1, at top, is north in the traffic network  1  to  6 . Coming from the south on Kölner Strasse  1 , the turn possibility  7  is to the right onto Beethoven-Strasse  5 . Driving along Beethoven-Strasse  5 , proceeding from turn possibility  7  in an easterly direction from Kölner Strasse, that is, to the right in FIG. 1, the possible turns on the left are  8  into Verdi-Strasse  2 ,  11  into Hinterer Waldweg  4 , and  12  into Bachstrasse  6 ; the possible turns on the right are  9  into Verdi-Strasse  2  and  10  into Mozart-Strasse  3 . 
     The vehicle  13  moves north on Kölner Strasse  1 , that is, upward from the bottom in FIG. 1, to turn possibility  7 . 
     By means of the process according to the invention, route information about a route traveled by the vehicle  13  with a terminal unit within a traffic network  1  to  6  can be transmitted  16  to a central traffic station  14  (by mobile radio, etc.), e.g., for monitoring navigation. Further, with the process according to the invention, information relating to a route, especially navigation aid information, can be transmitted  15  (by mobile radio, etc.) from the central traffic station  14  to the terminal unit in the vehicle  13 . 
     The transmission of route information relating to a route traveled by a vehicle in a traffic network will be described first in the following. The vehicle  13  drives along Kölner Strasse  1  in FIG. 1, turns east at turn possibility  7 , that is, to the right in FIG. 1, into Beethoven-Strasse  5  and drives along the latter until turn possibility  12 , whereupon it turns north-east at turn possibility  12 , that is, toward the upper right in FIG. 1, into Bachstrasse  6 . This route of the vehicle  18  is to be transmitted  16  from a terminal unit in the vehicle  13  to the central traffic station  14  to enable interactive navigation and/or for further use in the central traffic station  14 . A terminal unit in the vehicle  13  transmits a starting point of a route, e.g., based on its position which can be determined in the terminal unit, for example, by GPS. The route of the vehicle  13  can be transmitted  16  to the central traffic station in such a way that path points are defined in the terminal unit of the vehicle  13  wherever the vehicle turns off from a road. In the present case, a path point  7  is defined where the vehicle turns from Kölner Strasse  1  onto Beethoven-Strasse  5 ; another path point  12  is defined where the vehicle turns off from Beethoven-Strasse  5  into Bachstrasse  6 . The next road in the driving direction, the location of the path point and the driving direction after the path point are designated and transmitted for these path points. The next road  5  in the driving direction, namely, Beethoven-Strasse  5 , is designated at path point  7 ; the location of the path point is also designated, this location being determined, for example, by GPS; further, the driving direction after path point  7  is designated as “right” and/or “east.” In a corresponding manner, the next road, Bachstrasse  6 , in the driving direction of the route after path point  12 , the location of path point  12 , and the driving direction after path point  12 , that is, toward the upper right and/or northeast in this case, are designated in the route information for path point  12 . The location of a path point can be transmitted in the form of standardized geographic coordinates, for example, by a number in which the geographic longitude and latitude are given in a predetermined rounded off manner. The roads onto which a vehicle turns can be determined based on GPS and/or steering wheel angle with a digital map in the terminal unit in the vehicle  13 . Further, a simpler terminal unit for the vehicle  13  is possible, wherein, for example, in order to enable interactive navigation, it is assumed that the user enters a turnoff  7 ,  12  onto another road in the terminal unit manually and/or acoustically. 
     No route data are transmitted in this case concerning the turn possibilities  8 ,  9 ,  10 ,  11  from a road  5  which is not perceived by the vehicle  13 . 
     It is possible to detect the path of the vehicle  13  in the traffic network  14  based on the transmitted  16  route data. The central traffic station advisably has a digital map of the traffic network  1  to  6 . Roads can accordingly be correlated with the determined path of the vehicle  13  in the digital map in the central traffic station  14 . Based on the correlation, a navigation of the vehicle can be arranged interactively and/or a historical database can be set up and used for traffic information. 
     The transmission of route information concerning a route of a vehicle in a traffic network from the central traffic station  14  to a terminal unit in a vehicle  13  will be explained in the following. For example, the central traffic station  14  transmits  15  route information to a terminal unit in the vehicle  13  as a navigation aid for the vehicle  13 . 
     A navigation aid of the type mentioned above can be requested from the central traffic station  14  (via mobile radio, etc.) by the vehicle  13 , in particular while indicating its starting position and its desired target position. The central traffic station  14  determines with a route calculation program an optimum route for the vehicle  13 ; in this connection, the central traffic station  14  can take into account known backups, detours, accidents, distances in a digital map, lengths of different routes, etc. The central traffic station  14  initially transmits to a vehicle  13  the direction in which it should start driving. At a possible turnoff point  7  to  12 , the central traffic station  14  only transmits route information when the vehicle  13  should turn off from a road. Thus, route information about the turn possibilities  7 ,  12  is transmitted; no route information is transmitted concerning turn possibilities  8 ,  9 ,  10 ,  11 . The turn possibilities  7 ,  12  at which a vehicle  13  is to turn off from a road  1  or  5  into another road are defined in the central traffic station  14  as path points about which route information is to be transmitted. At path point  7 , the central traffic station  14  transmits to a terminal unit in the vehicle  13  the next road, Beethoven-Strasse  5 , following in the driving direction of the recommended route after path point  7  and the location of the path point as well as the driving direction which the vehicle should take after path point  7 . The road is transmitted as “Beethoven-Strasse” in particular when there is no digital map in the terminal unit. When the central traffic station  14  has the location of the path point  7  and the current location of the vehicle  13  (for example, from a GPS measurement in the vehicle  13  and transmission of the location to the central traffic station  14 ), the location of the path point  7  can be sent in the form of a distance (3 km). Further, it is possible to transmit the absolute geographic position of the path point  7  in the form of its geographic coordinates rounded off in a standardized manner or in some other manner. The driving direction which the vehicle  13  should take after path point  7  can be indicated as a relative direction with respect to the previous driving direction of the vehicle, that is, in particular left, right, hard left, soft left, etc. Further, the driving direction can be indicated as a compass point, namely, north, south, east, west or, with a more accurate resolution, north, northwest, west, southwest, south, southeast, east, northeast, wherein this is particularly useful when a compass and/or a position detection system (such as GPS) is present in the vehicle  13 . In a corresponding manner, the suggestion to turn into “Bachstrasse”, the position of path point  12  and the direction in which to turn into Bachstrasse is sent to the vehicle as route information at path point  12 . 
     FIG. 2 shows schematically in abstracted form the partial route of a vehicle in the section of the traffic network shown in FIG.  1 . It is also possible for a view of this kind to be shown on a display in the terminal unit in the vehicle  13  for the driver&#39;s information. Further, only information for the next path point, that is, for example, the circle on the left-hand side of FIG. 2 containing the detail, can also be shown on a display in the terminal unit in the vehicle  13 . The next path point can be displayed in such a way that north is on top as shown in FIG. 2, in a display in the terminal unit in the vehicle  13  or in such a way that the driving direction of the vehicle  13  extends upward on a display. In a corresponding manner, the information about path point  12  shown on the right-hand side in FIG. 2 (in the circle) can be displayed before path point  12 . Further, the information can also be made available to the user acoustically.