EP0790591A1 - Locationdatabase for determining routes within a road traffic network - Google Patents

Abstract

The database holds locations as location codes, each placed in a data set with pointers to the adjacent locations on the same route. Cross-references are also stored to the same points on other traffic routes. The cross-references are each formed from the location code of the location on the other route. Each location and route has only one cross-reference to the same point on another route, whereby cyclical cross-references are used for points on more than two routes.

Description

The invention relates to a location database for determining routes within a traffic route network and a radio receiver with a device for receiving and decoding digitally coded traffic reports.

The radio data system (RDS) enables an additional and inaudible transmission of digital data in parallel to radio programs in a data channel. Specifications of the radio data system for VHF radio can be found in Tech. 3244 - E, March 1984 of the European Runfunk Union (EBU). Radio receivers with suitable RDS decoders can record and decode transmitted data in addition to radio reception with the same receiver. 32 groups of 104 bits each are provided for data transmission, with each of the transmitted groups being assigned a specific service. Group 8a is currently intended for the transmission of digitally coded traffic reports.

The structure and coding of these traffic reports are in CEN Draft pr. ENV / 278/4/1/0011, which is based on the proposed standard ALERT C, November 1990, published by the RDS ATT ALERT Consortium. The essential elements of a traffic report are the location and the event. This information is cataloged, which means that a unique code is assigned to every traffic-relevant location and every traffic-relevant event. The chaining of the locations in the location table along existing streets shows the course. In addition to the usual facilities of a receiving device with an RDS decoder, facilities for decoding, storing, further processing and outputting the traffic reports are required to use the traffic message channel TMC (Traffic Message Channel).

The location databases required for decoding the digitally coded traffic reports consist of lists of junctions, motorway junctions, motorway triangles, departures to parking lots and similar locations, the locations on each traffic route (highway, federal road) being linked to one another by references. Since not all locations can be reached from both directions, the links for both directions are specified separately by entering a predecessor or successor for each location in the location database. If a location does not have a successor, for example at the end of a street, this is indicated by a special entry. Places, such as intersections, which are located on several traffic routes are entered with all of these traffic routes with different location codes.

This location database structure, in which no relationships between the same locations can be identified on different traffic routes, is sufficient for decoding the Traffic-news. The same name is then provided for the output of the decoded traffic reports for a respective same location, which is specified in coded form in the location database each time the same location occurs. However, this information is only used to output the actual name as an alphanumeric display or voice output.

An advantage of digitally coded traffic reports is that they are not available as speech patterns, but as data that can be processed in a variety of ways. This makes it possible, for example, to select the traffic reports so that the driver receives only those traffic reports that relate to his expected route and any diversions that may be suitable for this.

It is a prerequisite for such a selection that the expected route is known to the computer performing this selection. This can be done by manually entering the expected route. Another option is to enter the destination and let the computer determine the route. Suitable computing methods are known and are available, for example, within PC programs. However, a road map is required that contains the streets and intersections in question, as well as the distances between the intersections and other locations.

The object of the present invention is to provide a location database for the determination of routes within a traffic route network, which also enables decoding of digitally coded traffic reports according to predetermined methods.

This object is achieved according to the invention in that a location database provided for decoding digitally coded traffic reports contains the locations required for decoding the digitally coded traffic reports as location codes, with a location code in each case containing a traffic route and references to neighboring locations on the same traffic route in a data record are assigned, is also provided with cross-references to the same places on other traffic routes. It is preferably provided that the cross-references are each formed by the location code of the location on the other traffic route.

The location database according to the invention has the advantage, in addition to the possibility of using the two above-mentioned tasks, that only a small storage capacity is required per location. In addition, in the location database according to the invention, location databases that have already been created for the TMC system can largely be used by merely adding information.

A reduction in the storage capacity is possible according to a further development in that only one cross-reference to the same location on another traffic route is provided per location and traffic route, the cross references being carried out cyclically in locations on more than two traffic routes. This means that each of these locations only receives a cross-reference. It is then not necessary to provide storage space per location for the largest number of possible traffic routes on which a location is located.

In the known location database for the TMC system, there are many locations which, apart from predecessor / successor relationships, have no links to other streets or locations. In the following, in connection with the location database according to the invention, a location is designated as genuine if it has a cross-reference. The other places are considered fake designated. When determining a route, a search is made from entry to entry, so that many fake places are processed without further measures in the location database according to the invention, which results in a considerable amount of computation. This effort can be reduced with another development of the invention in that in the data records for locations on a traffic route which are also on a further traffic route, references to the respectively next locations on the traffic route which are also on at least one further traffic route, are registered. This enables the search algorithm to jump directly from one real location (network node) to the next.

Location databases that are used to decode digitally coded traffic reports do not have to contain a complete road network. In such location databases, for example, crucial road connections are missing in some places: partly because sections of the motorway are still under construction or because connections are not listed in the location database. With a suitable coding of the traffic reports that takes these limits of the location databases into account, the traffic reports can still be decoded.

When planning the route, the driver will still take the route into account and, for example, accept to drive a few kilometers of the main road instead of a detour via motorways. So that the determination of the routes can nevertheless take these streets into account, which are shown as dead ends in the location database, according to another development of the invention, location databases which contain the coordinates of the locations provide for locations which are furthermore provided by a traffic route not intended for coding traffic reports are linked, cross-referenced.

From these cross-references and the inequality of the coordinates of the affected locations, the computer determining the route can recognize that the affected locations are not the same, but are the end points of another traffic route.

In the case of location databases, in which distances between the locations are specified, the consideration of traffic routes not intended for decoding is possible by the fact that selected locations which, besides a traffic route provided for decoding, lie on a further traffic route not intended for decoding , a reference to the further traffic route is provided and that the further traffic route with the locations where there are references to the further traffic route is listed in the location database. The length of the other traffic routes can be taken into account in that distances between the locations are stored on the further traffic routes.

An evaluation of the additional routes when determining the route is also possible in that the street type (location type) is stored for the additional routes.

Those data records which contain cross-references and references to further traffic routes have a larger number of information bits. Depending on the design of the location database according to the invention in detail, such data records can be longer by several words, for example 16-bit words, than data records of locations without cross-references and references. Filling these additional digits with spaces creates a database with a constant data record length. Although this simplifies the administration of such a database, it leads to increased memory requirements. In order to keep such an increase as low as possible, according to another development, there is one in each of the data records Additional information from at least one bit about the presence of cross-references and / or references and possibly about the number and / or type of cross-references and / or the references is contained.

A radio receiver with a device for receiving and decoding digitally coded traffic reports using a location database is characterized by a device for determining routes using the location database according to one of the preceding claims.

In order to take into account the often lower travel speed on the other traffic routes, it can be provided in the radio receiver according to the invention that when routes are determined, the lengths of the traffic routes are assessed in accordance with the respective type of road.

A further development of the radio receiver according to the invention is that the determined routes are used for the selection of received digitally coded traffic reports in such a way that only those traffic reports are output which relate to the determined routes. According to a further development, it can be provided that the determined routes can be represented graphically.

Fig. 1

einen Ausschnitt aus einer ersten erfindungsgemäßen Ortsdatenbank,

Fig. 2

eine schematische Darstellung einer Kreuzung von zwei Verkehrswegen,

Fig. 3

eine schematische Darstellung einer Kreuzung von drei Verkehrswegen,

Fig. 4

einen Auszug aus einer zweiten erfindungsgemäßen Ortsdatenbank und

Fig. 5

eine Straßenkarte zur Erläuterung der Ortsdatenbank gemäß Fig. 4.

Exemplary embodiments of the invention are shown in the drawing using several figures and are explained in more detail in the following description. It shows:

Fig. 1

a section from a first location database according to the invention,

Fig. 2

a schematic representation of an intersection of two traffic routes,

Fig. 3

a schematic representation of an intersection of three traffic routes,

Fig. 4

an extract from a second location database according to the invention and

Fig. 5

4 shows a road map to explain the location database according to FIG. 4.

The section of a location database shown in FIG. 1 contains six data records, four of which relate to locations on the A1 motorway, one to a location on the A61 motorway and another to a location on the A53 motorway. As with the location database according to ALERT C, each data record contains a location code, a location type, the specification of the road number, the type of connection point, the name of the respective location and references to the previous and the following location (offset +, offset-). For the sake of clarity, the place names are shown in full in the place database shown, but in the place database that is implemented there is a place name code under which the place name is stored in a place name database. This has the advantage that place names of different lengths need not be taken into account in the place database, that the coded place names require less storage space and that place names for foreign drivers may be listed in the place name database.

As can be seen from FIG. 1, geographically the same places - in this case the place Bliesheim - are listed in the place database completely independently of one another and also provided with different place codes. To enable route determination, there are cross references in the location database shown (cross-ref.) For those locations registered that lie on several traffic routes. Since the place Bliesheim - meaning not the municipality, but the motorway junction - is located on three traffic routes, the cross references are cyclically interchanged, so that only one cross reference is necessary for each data record.

The location code 4144 (Bliesheim on the A1) contains references to the previous location 4143, the subsequent location 4145 and the geographically identical location 6380 on the A61 motorway. The latter contains a reference to the location 7235 on the A553 motorway and this in turn a cross-reference to the location 4144 on the A1 motorway. A program for determining routes can thus easily recognize that locations 4144, 6380 and 7235 represent a single location within the transport network. Incidentally, there is a special feature in the data record for location 7235. Since the A553 motorway ends at this location, a special indicator is entered as the following location, namely 0xffff.

00:

kein Querverweis, beim Auslesen der Datenbank aus dem Speicher werden die auf "Offset-" folgenden Daten als Beginn des nächsten Datensatzes angesehen,

01:

Querverweis auf einen anderen Verkehrsweg,

10:

"Sprungverweis", d.h. Hinweis auf einen echten Ort,

11:

"fiktiver Verweis", d.h. Hinweis auf einen weiteren, fiktiven Verkehrsweg.

As already mentioned, storage space can be saved in the location database according to the invention by using additional information. If two bits are inserted per data record in the database according to FIG. 1, these can have the following meaning, for example:

00:

no cross-reference, when reading the database from the memory, the data following "offset" are regarded as the start of the next data record,

01:

Cross-reference to another traffic route,

10:

"Jump reference", ie reference to a real place,

11:

"Fictitious reference", ie reference to another, fictitious traffic route.

In the last three cases, the data following "Offset" is interpreted as a cross-reference or hint.

2 shows sections of two streets A, B in the area of an intersection. In the known location database, locations 1, 2, 3, 4 are entered as belonging to street B, while locations 5, 6, 7, 8 are designated as locations on street A. Arrows between these locations indicate the references Offset + and Offset-. Geographically, however, locations 3 and 7 are the same, which is documented by a cross-reference 9 in the location database according to the invention.

In the example shown in FIG. 3, another street C crosses streets A and B at the same location. In the known location database, however, the locations 10, 11, 12, 13 are only listed in connection with the street C. As already explained in connection with FIG. 1, the locations 3, 7 and 12 are therefore provided with cross-references 14, 15 and 16, which in cyclical order indicate a different "location" within the intersection.

FIG. 4 shows a section of a location database which contains locations in the area shown as a road map in FIG. 5. 4, the A31 motorway has a gap between the Nürnberg-Gostenhof and Nürnberg-Hafen-Ost junctions, which can be recognized by the entries 0xffff. Since the use of inter-city expressways in between makes sense, they must be taken into account when determining the route. In the location database according to FIG. 4, cross-references to locations 15006 and 15007 are therefore given at locations 6644 and 6645 on a fictional road F between these two locations in relation to the location database. A designation FCT_LOC was chosen as the location type for these two locations, which means that these locations lie on a fictitious street. According to their property as end points of this fictitious street, the locations are provided with references Offset +, Offset- and 0xffff. These locations also have cross-references to the locations 6644 and 6645, with which they each form a geographical location.

Since the shortest route and alternatives are to be found when determining the route, information about the length of a network edge is required as an optimization criterion. The predecessor and successor of a node are specified in the location database, but there is no information about the evaluation of these relationships. It is therefore necessary to add to this information, but evaluation does not necessarily mean the distance, since other criteria can also play a role in the choice of route. So there is a factor that can be a combination of route, road conditions, average journey time and other influences.

A simple form of the evaluation criterion is the distance, which can exist as such in the location database or can be calculated as the straight line between two locations with the coordinates x ₁ , y ₁ and x ₂ , y ₂ as follows: $${\text{s = [(x}}_{\text{2nd}}{\text{-x}}_{\text{1}}{\text{)}}^{\text{2nd}}{\text{+ (y}}_{\text{2nd}}{\text{-y}}_{\text{1}}{\text{)}}^{\text{2nd}}{\text{]}}^{\text{½}}\text{.}$$

Diese Abschätzung ist von einem einfachen Prozessor wesentlich schneller durchzuführen.Another form of length evaluation for route search can be done according to the so-called taxi driver standard using the following equation: $${\text{s = | x}}_{\text{2nd}}{\text{-x}}_{\text{1}}{\text{| + | y}}_{\text{2nd}}{\text{-<figure-callout id="1" label="y" filenames="imgf0001.png,imgf0003.png" state="{{state}}">y</figure-callout>}}_{\text{1}}\text{|.}$$

This estimation can be carried out much faster by a simple processor.

Claims (13)

Location database for the determination of routes within a traffic route network, characterized in that a location database provided for decoding digitally coded traffic reports contains the locations required for decoding the digitally coded traffic reports as location codes, with each location code indicating a traffic route and references to neighboring ones on the same Locations located in the traffic route are assigned in a data record, furthermore provided with cross references to the same locations on other traffic routes. Location database, characterized in that the cross-references are each formed by the location code of the location located on the other traffic route. Location database according to one of claims 1 or 2, characterized in that only one cross-reference to the same location on another traffic route is provided for each location and traffic route, the cross-references being carried out cyclically for locations on more than two traffic routes. Location database according to one of the preceding claims, characterized in that in the data records for locations on a traffic route which are also on a further traffic route, references to the respectively next locations on the traffic route which are also on at least one further traffic route are entered. Location database according to one of the preceding claims, the coordinates of the locations being indicated, characterized in that locations which are connected by a traffic route not intended for coding traffic reports are also provided with mutual cross-references. Location database according to one of claims 1 to 4, wherein distances between the locations are indicated, characterized in that further selected locations which, apart from on a traffic route provided for the decoding, lie on a further traffic route not provided for the decoding, an indication of the another traffic route is provided and that the further traffic route with the locations where there are references to the further traffic route is listed in the location database. Location database according to claim 6, characterized in that distances between the locations are stored on the further traffic routes. Location database according to one of claims 6 or 7, characterized in that the road type (location type) is stored for the further traffic routes. Location database according to one of the preceding claims, characterized in that in the data records in each case additional information from at least one bit about the presence of cross-references and / or references and where appropriate, on the number and / or type of cross-references and / or references is included. Radio receiver with a device for receiving and decoding digitally coded traffic reports using a location database, characterized by a device for determining routes using the location database according to one of the preceding claims. Radio receiver according to Claim 10, characterized in that when routes are determined, the lengths of the traffic routes are assessed in accordance with the respective type of road. Radio receiver according to one of claims 10 or 11, characterized in that the determined routes are used for the selection of received digitally coded traffic reports in such a way that only those traffic reports are output which relate to the determined routes. Radio receiver according to one of claims 10 to 12, characterized in that the routes determined can be represented graphically.

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