Method and processing device for positioning an object on a target digital map embedded in a vehicle

Abstract

This disclosure relates to a method (30) for positioning, by means of a processing device (20), an object on a target digital map representing a road network, comprising: a reception (S30) of location information for said object, including a road segment identifier and a relative position of said object on said road segment, a search (S31) for the road segment identifier from the location information in a database associated with the target digital map, said database storing a plurality of road segment identifiers associated with respective geometric models,when the road segment identifier from the location information is present in the database: a determination (S32) of a map position of the object in the target digital map based on the geometric model associated with said road segment identifier from the location information and based on the relative position of said object on said road segment. Figure accompanying the summary: Figure 3,

Description

Title of the invention: Process and device for positioning an object on a target digital map embedded in a vehicle. Technical field

[0001] The present invention belongs to the field of connected vehicles, and relates more particularly to a method and a processing device for positioning an object on a target digital map embedded in a vehicle. State of the art

[0002] Nowadays, many motor vehicles are equipped with a display device implemented to display, among other things, a digital map representing a road network on which said motor vehicle travels.

[0003] For example, the display device can display the position of the motor vehicle on the digital map, from a geographical position measured by a GPS receiver (“Global Positioning System”) of said motor vehicle.

[0004] However, due in particular to measurement errors of the GPS receiver and / or errors in the representation of the road network in the digital map, the measured geographical position, when transposed directly into the digital map, does not necessarily result in the motor vehicle being positioned on the correct road of the represented road network, or even does not result in the motor vehicle being positioned on a road of the represented road network.

[0005] In order to reduce positioning errors of the motor vehicle on the road network represented by the digital map, it is known to implement map-matching algorithms (“map-matching” in the Anglo-Saxon literature, see for example [WOLTCHE2021]).

[0006] Following other examples, the display device can display the position of points of interest on the road network represented by the digital map, for example, the position of traffic jams, an accident, another motor vehicle stopped on the road, etc. In such a case, the position of the point of interest is generally received from a remote server. Typically, the remote server determines the position of the point of interest in a so-called "source" digital map, for example, by implementing a map-matching algorithm. However, the source digital map, considered by the remote server, may be different from the so-called "target" digital map used by the motor vehicle. For example, the source digital map and the target digital map may be established by different digital map providers. In such a case, the position on the map of the point of interest in The source digital map, which is located on a road in the road network within the source digital map, is not necessarily located on a road, or even the correct road, in the target digital map. Indeed, the geometric representation of the same road can vary from one digital map to another, and it is therefore necessary to implement map matching algorithms to perform cross-matching between the different digital maps.

[0007] Even though it is known in such a context (source digital map potentially different from the target digital map) to express the position of the point of interest considered in a format independent of the source digital map and the target digital map (see for example the OpenLR standard), it remains nonetheless necessary to use a map matching algorithm to position the point of interest in the target digital map.

[0008] In the case of a remote server that must centrally position various points of interest for numerous motor vehicles, this implies making many calls to map-matching algorithms. These algorithms are very demanding, particularly in terms of computational complexity. Consequently, frequent calls to these algorithms impose significant constraints on computing power. Furthermore, the computation time required to position a point of interest on a target digital map can become considerable, especially with numerous simultaneous calls to map-matching algorithms.

[0009] Such positioning of a point of interest on a digital map embedded in a motor vehicle can also be implemented, alternatively or in addition to displaying the point of interest by a display device, to control certain functions of the motor vehicle. For example, such positioning of a point of interest on the target digital map can be used by an adaptive cruise control (ACC) system of said motor vehicle to adjust the vehicle's speed according to the position of the point of interest relative to said vehicle. Such applications require the ability to quickly obtain the position of the point of interest on the target digital map in order to anticipate the actions to be taken. Computation time is therefore a particularly important criterion for such applications. Description of the invention

[0010] The present invention aims to overcome all or part of the limitations of prior art solutions, in particular those described above, by proposing a a solution that allows, on average at least, the reduction in computational complexity and latency associated with positioning a given object on a target digital map.

[0011] To this end, he proposed, according to a first aspect, a method for positioning, by means of a processing device, an object on a target digital map representing a road network, said method comprising: - the receipt of location information for said object, said location information including or enabling the determination of a road segment identifier, said road segment identifier describing a road segment of the road network on which the object is located, and a relative position of said object on said road segment, - a search for the road segment identifier from the location information (i.e., received in the location information or determined from it) in a database associated with the target digital map, said database storing a plurality of road segment identifiers associated respectively with geometric models, each geometric model describing the geometry in the target digital map of the representation of the road segment described by the associated road segment identifier, - when the road segment identifier from the location information is present in the database: a determination of a map position of the object in the target digital map based on the geometric model associated in the database with said road segment identifier from the location information and based on the relative position of the object on the road segment.

[0012] Thus, the present invention relies on a decomposition of the road network into road segments, each road segment corresponding to a portion of a road within the segment. The location of the object (for example, the vehicle carrying the target digital map, or a point of interest for said vehicle carrying the target digital map) can then be indicated by identifying the road segment on which the object is located, as well as a relative position of the object on that road segment. By "relative position," we mean the position of the object expressed in a reference frame associated with the road segment.

[0013] Furthermore, the present invention relies on the creation of a database that allows for the retrieval, for each road segment identified in said database, of a geometric model describing the geometry of the representation of said road segment in the target digital map. Such a geometric model is therefore intrinsically linked to the target digital map, given that the geometry of the representation of the same road segment can vary from one digital map to another. other. Such a geometric model of the road segment on which the object to be positioned is located makes it possible to determine, from the relative position, the position on the map of this object in the target digital map in a quick and simple way, without having to implement a map matching algorithm.

[0014] In the case of a road segment that is not identified in the database, the road segment identifier, which describes the road segment in question, can be used to implement a map-matching algorithm to retrieve the representation of this road segment in the target digital map. If necessary, it is possible, for example, to determine a geometric model of the representation of this road segment in the target digital map and to store this geometric model in the database in association with the corresponding road segment identifier for future use (so as not to have to implement a map-matching algorithm again for the same road segment).

[0015] In particular embodiments, the positioning method may further include one or more of the following optional features, taken individually or in all technically possible combinations.

[0016] In specific embodiments, when the road segment identifier derived from the location information is absent from the database, the method comprises: - a search, within the target digital map, for points representing the road segment described by the road segment identifier derived from the location information, - a determination of the object's position on the map based on the relative position of said object on the road segment and based on the points representing the road segment in the target digital map.

[0017] In specific embodiments, when the road segment identifier derived from the location information is absent from the database, the method comprises: - the determination of a geometric model describing the points representing, in the target digital map, the road segment described by the road segment identifier derived from the location information, - a storage, in the database, of the road segment identifier derived from the location information in association with the determined geometric model.

[0018] In particular embodiments, the road segment identifier comprises at least two attributes of the road segment chosen from the following list: - a geographical position of one end of the road segment, a geographical position of a point on the road segment distinct from ends of said road segment, a type of road of the road segment, a length of the road segment, a direction of traffic on the road segment.

[0019] In particular embodiments, the relative position is representative of a distance measured along the road segment with respect to the geographical position of an end of said road segment.

[0020] In particular embodiments, location information is formatted according to the OpenLR format.

[0021] In particular embodiments, the geometric model corresponds to a WKT character string or a WKB binary string.

[0022] In particular embodiments, the positioning method includes a transmission of the determined map position to a display device of a vehicle and / or to an adaptive cruise control of said vehicle.

[0023] In particular embodiments, the position on the map of the object to be used by a vehicle carrying the target digital map, said object corresponds to said vehicle or to a point of interest for said vehicle.

[0024] In particular embodiments, the processing device is remote from the vehicle or mounted in said vehicle.

[0025] In particular embodiments, the location information of said object includes a road sub-segment identifier, a road segment identifier identification code and a relative position of said object on the road sub-segment, and the method includes a determination of the road segment identifier and the relative position of said object on said road segment according to a conversion table storing a plurality of identification codes associated respectively with road segment identifiers and, for each stored road segment identifier, identifiers of road sub-segments composing said road segment and relative positions of said road sub-segments on the road segment.

[0026] According to a second aspect, a computer program product is proposed comprising instructions which, when executed by a processing device comprising at least one memory and at least one processor, configure said processing device to implement a positioning method according to any one of the implementation modes of this disclosure.

[0027] According to a third aspect, a computer-readable recording medium is proposed on which is recorded a set of instructions which, when executed by a processing device comprising at least one memory and at least one processor, configure said processing device to implement a positioning method according to any of the implementation methods of this disclosure.

[0028] According to a fourth aspect, a processing device is proposed comprising at least one processor and at least one memory, configured to implement a positioning method according to any one of the implementation modes of this disclosure.

[0029] According to a fifth aspect, a vehicle, such as a motor vehicle, is proposed, comprising a processing device according to any one of the embodiments of this disclosure. Presentation of the figures

[0030] The invention will be better understood upon reading the following description, given by way of non-limiting example, and made with reference to the figures which represent: - [Fig. 1] [Fig. 1]: a schematic representation of a vehicle connected to a wireless communication network, - [Fig.2] [Fig.2]: a schematic representation of an example implementation of a processing device for positioning an object on a target digital map, - [Fig.3] [Fig.3]: a diagram illustrating the main steps of an example implementation of a method for positioning an object on a target digital map, - [Fig.4] [Fig.4]: a schematic representation of a target digital map illustrating map matching and the determination of a geometric model for the representation of a road segment.

[0031] In these figures, identical reference numerals from one figure to another designate identical or analogous elements. For clarity, the elements shown are not to scale unless otherwise stated.

[0032] Furthermore, the order of steps shown in these figures is given only as a non-limiting example of this disclosure which may be applied with the same steps performed in a different order and / or with steps performed in parallel and / or jointly. Description of the implementation methods

[0033] Figure 1 schematically represents a vehicle 10, for example a motor vehicle, traveling on a road in a road network. The vehicle 10 is a connected vehicle comprising a wireless communication device (not shown in the figures) for example adapted to exchange data with a base station 50 of a wireless communication network. The wireless communication device of the vehicle 10 can implement one or more wireless communication protocols, to exchange data with the wireless communication network, and can be for example a 3G, 4G, 5G, WiFi, WiMax, etc. wireless communication device.

[0034] Figure 1 also represents a processing device 20, configured to position an object on a target digital map 11 carried in the vehicle 10, said target digital map 11 representing the road network on which the vehicle 10 travels. The object corresponds, for example, to the vehicle 10, or to a point of interest for said vehicle 10 (traffic jam, accident, another motor vehicle stopped on the road, etc.). By "positioning the object on the target digital map," we mean matching location information of the object with the map data of the target digital map 11, in order to determine the most probable position on the target digital map 11 of the point likely to represent the object according to the location information.Specifically, in the case of an object located on a road, this implies ensuring that the map position of this object is located on the representation of this road in the target digital map 11.

[0035] In the non-limiting example illustrated by [Fig.1], the processing device 20 is remote from the vehicle 20, so that the vehicle 10 can connect to the processing device 20 via the wireless communication network and optionally via a network core 51, in order to receive the map position of the object in the target digital map 11.

[0036] Following other examples, the processing device 20 can be mounted in the vehicle 10. Where appropriate, the processing device 20 can receive location information of the object, as described below, via the wireless communication network, determine the position on the map of the object in the target digital map 11 and transmit this position on the map to other equipment of said vehicle 10, for example via a local network (not shown in the figures) of said vehicle.

[0037] Regardless of the location of the processing device 20 (distant from the vehicle 10 or on board said vehicle 10), the position on the map of the object, determined by the processing device 20, is for example transmitted to one or more pieces of equipment (not shown in the figures) of the vehicle 10, for example transmitted to a display device of the vehicle 10, to an adaptive cruise control of said vehicle 10, etc.

[0038] Fig. 2 schematically represents an example of the realization of a processing device 20 for positioning an object on a target digital card 11.

[0039] As illustrated in [Fig. 2], the processing device 20 comprises a processing circuit 21. The processing circuit 21 comprises, for example, one or more processors 210 (CPU, DSP, GPU, FPGA, ASIC, etc.). In the case of several processors 210, these can be integrated into the same equipment and / or integrated into physically separate equipment communicating with each other. The processing circuit 21 also includes one or more memories 211 (magnetic hard drive, electronic memory, optical disc, etc.) in which, for example, a computer program product 212 is stored, in the form of a set of program code instructions to be executed by the processor(s) to implement all or part of the steps of a positioning process 30 on the target digital card 11, which will be described below.

[0040] As illustrated in [Fig. 2], the treatment device 20 also comprises a Communication module 22 is adapted to exchange data with other devices, particularly with equipment in vehicle 10 (via the wireless communication network when the processing device 20 is remote from vehicle 10, or via a local network of said vehicle when said processing device 20 is on board vehicle 10). The communication module 22 of the processing device 20 can implement one or more communication protocols, wired (Ethernet, optical, etc.) or wireless (3G, 4G, 5G, WiFi, WiMax, etc.).

[0041] Through the communication module 22, the processing device 20 is adapted to receive location information of an object and to transmit a map position of this object in the target digital map 11 (for example to a display device and / or to an adaptive cruise control of the vehicle 10).

[0042] Fig. 3 schematically represents the main steps of an example of implementation of a method 30 for positioning an object on the target digital card 11, which are implemented by the processing device 20.

[0043] As illustrated by [Fig. 3], the positioning method 30 comprises a step S30 receiving location information of the object to be positioned, for example by means of communication module 22.

[0044] The location information includes a road segment identifier that describes the road segment of the road network on which the object is located. The location information also includes a relative position of said object on said road segment.

[0045] As indicated above, the road segment identifier describes the road segment on which the object to be positioned is located, and a road segment corresponds to a portion of road. The length of a road segment is, for example, between a few tens of meters and a few hundred kilometers, and can vary from one road segment to another, for example depending on the type of road to which the road segment belongs.

[0046] For example, the road segment identifier provides attributes of said road segment. The indicated attributes of the road segment are independent attributes of the representation of said road segment in the target digital map 11, but which must allow the points representing the road segment to be found in the target digital map 11 (or, more generally, in any digital map representing the road segment in question).

[0047] The following are non-limiting examples of attributes of the road segment that can be provided by the road segment identifier.

[0048] Following an example, the road segment identifier may indicate the geographic position of at least one endpoint of the road segment, for example, the geographic position of a starting point of the road segment and / or the geographic position of an ending point of said road segment. It should be noted that, generally speaking, "geographic position" means the position in a reference frame. For example, the geographic position is indicated in the form of geographic coordinates comprising at least the latitude and longitude, and optionally the altitude of the point in question on Earth.

[0049] Following another example, the road segment identifier may indicate the geographical position of at least one intermediate point of the road segment, an intermediate point being a point of the road segment that is distinct from the ends of said road segment.

[0050] Following another example, the road segment identifier can indicate a road type within the road segment. A road type refers to the classification of roads based on their physical characteristics, their use, and their importance within a given road network. These classifications may vary from country to country, but they include, for example, categories such as motorways, main roads, secondary roads, or residential roads. For instance, in some functional road classifications (FRC), a road of a higher functional class is likely to be used for long-distance journeys (motorways, for example), and a road of a lower functional class is likely to be used only for local journeys.For example, 0 could be the highest functional class, and 7 the lowest functional class.

[0051] Following another example, the road segment identifier may indicate a length of the road segment, measured along said road segment, between its endpoints.

[0052] Following another example, the road segment identifier can indicate a direction of traffic on the road segment. The direction of traffic can, for example, make it possible to distinguish different traffic lanes within the same road, in particular.

[0053] Increasing the number of attributes indicated by the road segment identifier reduces the risk of confusing the road segment in question with another in the target digital map 11. In certain implementation modes, the identifier a road segment includes at least two of the road segment attributes described above, namely: the geographical position of at least one end of the road segment, the geographical position of at least one intermediate point of the segment truck driver, the type of road in the road segment, the length of the road segment, the direction of traffic on the road segment.

[0054] For example, the road segment identifier can indicate the geographical positions of the two ends of the road segment, the type of road of the road segment and, optionally, the direction of traffic on the road segment. It is also possible to optionally indicate the geographical position of one or more intermediate points of the road segment.

[0055] Following another example, the road segment identifier can indicate the geographical position of a single endpoint of the road segment (for example, the starting point), the type of road of the road segment, the length of the road segment and, optionally, the direction of travel on the road segment. It is also possible to optionally indicate the geographical position of one or more intermediate points of the road segment.

[0056] Part a) of [Fig.4] schematically represents an example of a target digital map 11 representing a road network comprising four roads RDI, RD2, RD3 and RD4. Of course, in practice, a digital map can include a much larger number of roads and can cover a geographical area of ​​much larger dimensions than that illustrated by part a) of [Fig.4].

[0057] Part a) of [Fig.4] also shows certain attributes indicated by a received road segment identifier, which is supposed to describe a road segment of the RD3 road.

[0058] The received road segment identifier includes, in particular, the geographical positions of the endpoints of the road segment. After transposing these geographical positions into the reference frame of the target digital map 11, it is observed that the points representing these endpoints, designated by EX1 and EX2, are not located exactly on the representation of road RD3, but are situated between roads RD2 and RD3. In this example, the geographical positions of the endpoints of the road segment are therefore not sufficient on their own to definitively identify road RD3 as the one to which the road segment described by the received road segment identifier belongs. In this example, the received road segment identifier also includes the type of road segment. Since roads RD3 and RD2 are of different types, there is therefore no longer any ambiguity between road RD3 and road RD2, and the The road segment is determined to belong to the RD3 road. Therefore, the road segment can be determined by projecting endpoints EX1 and EX2 onto the RD3 road. The representation of the road segment in question corresponds to the portion of the RD3 road located between these projections. Projecting an endpoint onto the RD3 road is equivalent to finding a point belonging to the RD3 road that likely corresponds to the received geometric position representation for that endpoint. For example, projecting an endpoint onto the RD3 road is equivalent to finding the point on the RD3 road that is closest to the considered endpoint EX1 or EX2. If the received road segment identifier also includes the direction of travel, this projection can further be made onto the lane of the RD3 road that is compatible with the indicated direction of travel.

[0059] Generally, the determination of the points of the target digital map 11 from a road segment identifier can be carried out using any map matching algorithm known to a person skilled in the art.

[0060] As indicated above, the location information further includes the relative position of the object on the road segment described by the road segment identifier. "Relative position" means the position of the object expressed in a reference frame associated with the road segment. For example, the relative position represents a distance measured along the road segment from the geographic position of one end of said road segment. For example, the relative position is expressed in meters, or as a percentage of the length of the road segment, etc. Once the points representing the road segment have been identified on the target digital map 11, the relative position can therefore be used to find the object's position on the map, that is, to locate the position on the target digital map 11 of the point likely to represent the object.

[0061] In general, this disclosure is not limited to a particular format for location information (road segment identifier and relative position), and the choice of a particular format is only a non-limiting variant of implementation.

[0062] In preferred implementation modes, location information is advantageously formatted according to the OpenLR format, which is considered to be known to the person skilled in the art (see [OPENLR-V1.5-REV2]). In such a case, the object's location information is, for example, provided in the form of a "point along a line" ("point along line" in [OPENLR-V1.5-REV2]). For example, the relative position corresponds to an "offset" (fields "POFF" or "NOFF" in [OPENLR-V1.5-REV2]) and the road segment identifier corresponds to the fields "First LRP" and "Last LRP" in [OPENLR-V1.5-REV2].

[0063] However, as indicated above, other formats are possible, particularly for the road segment identifier, provided they allow for the clear identification of a portion of the road network. In particular, it is possible to use other methods of dynamic location referencing (DLR), for example AGORA-C.

[0064] As illustrated in [Fig. 3], the positioning method 30 then includes a step S31 of searching for the received road segment identifier in a database associated with the target digital map 11, which has been previously established. This database stores a plurality of road segment identifiers associated respectively with geometric models, each geometric model describing the geometry in the target digital map 11 of the representation of the road segment described by the associated road segment identifier.

[0065] Generally speaking, the term "database" here refers to a memory adapted to store several pairs (road segment identifier / geometric model), and in which it is possible to search among the stored pairs for the presence of a specific road segment identifier (received in the object's location information) in order to retrieve the associated geometric model. The database is, for example, integrated into the processing device 20 (for example, a memory 211 of said processing device 20). In other examples, the database is located remotely from the processing device 20, in which case the processing device 20 accesses the database, for example, via the communication module 22.

[0066] For example, the database can be built up over time by storing the results of previous calls to map-matching algorithms. For example, when the processing device 20 receives location information, it can implement a map-matching algorithm to determine points representing the road segment described by the received road segment identifier. Part b) of [Fig. 4] schematically represents the points on the target digital map 11 representing the road segment described by the geometric positions of the endpoints EX1 and EX2, as illustrated by part a) of [Fig. 4], but also by the road type and direction of travel included in the received road segment identifier. From these points, it is possible to form a geometric model MG of the representation of said road segment on the target digital map 11.The geometric model describes the successive positions in the target digital map 11 of the points representing the road segment under consideration. The geometric model thus determined can be stored in the database, in association with the received road segment identifier (i.e. as a new (road segment identifier / geometric model) pair), for use. Subsequently, for example, if location information is provided in OpenLR format, the road segment identifier can be obtained by retaining only the fields whose values ​​remain unchanged if other location information is received for the same road segment of the road network. In other words, if location information is provided in OpenLR format, the road segment identifier can be obtained by removing fields that are not used to statically identify the road segment. Specifically, the "offset" field (fields "POFF" or "NOFF"), when present, corresponds to the relative position and is therefore not part of the road segment identifier.

[0067] As indicated above, the geometric model describes the successive positions in the target digital map 11 of the points representing the road segment under consideration. In preferred implementation modes, the geometric model corresponds to a string of characters known as "well-known text" (WKT in the English literature) or to a binary string known as "well-known binary" (WKB in the English literature). However, this disclosure is not limited to a particular format for the geometric model, and the choice of a particular format is only one non-limiting implementation variant of this disclosure.

[0068] As illustrated in [Fig. 3], when the received road segment identifier is found in the database (reference S31a in [Fig. 3]), this means that a geometric model representing the road segment in question already exists in the database in the target digital map 11 (and therefore it is not necessary to use a map-matching algorithm to position the object on the target digital map 11). The processing device 20 retrieves this geometric model and uses it in a step S32 to determine the object's position on the map based on the received relative position. Indeed, the relative position makes it possible to identify the point that is supposed to represent the object in the geometric model. The position of this point in the target digital map 11, provided by the geometric model, can be used as the object's position on the map. Part b) of [Fig.4] also represents, for the geometric model MG associated with the road segment considered, the position on map PC of the object, determined from the relative position received.

[0069] When the received road segment identifier is not found in the database (reference S31b in [Fig. 3]), this means that there is no geometric model in the database representing the road segment in question in the target digital map 11. In such a case, the positioning method 30 includes a step S33 for searching, in the target digital map 11, for points representing the road segment described by the received road segment identifier. This step S33 puts for example, implements a map matching algorithm, as described previously. Then, the positioning process 30 includes a step S34 of determining the position on the map of the object as a function of the relative position of said object on the road segment and as a function of the points representing the road segment in the target digital map 11.

[0070] As previously stated, it is advantageous to be able to reuse the results of the search step S33 later, so as not to have to implement a map-matching algorithm if a request to locate an object on the same road segment is received subsequently. In such a case, the points representing the road segment in the target digital map 11 can optionally be used to produce a geometric model MG of that road segment, for example by encoding the positions of these points as a WKT character string or a WKB binary string. If necessary, the geometric model MG determined for that road segment can be stored in the database, in association with the road segment identifier received during step S30, for later use.

[0071] In some implementation examples, the location information received does not directly include the road segment identifier and the relative position of the object on said road segment, but includes information enabling the determination of said road segment identifier and said relative position of the object on said road segment.

[0072] For example, it is possible to store, in the database, identifiers and geometric models of large road segments in order to reduce the number of entries in the database. Where applicable, the received location information may designate a road subsegment belonging to a road segment whose identifier is stored in the database, this road segment being composed of several road subsegments. For example, the received location information may include a road subsegment identifier and a relative position of the object on said road subsegment (for example, in OpenLR format), as well as an identification code for the road segment identifier describing the road segment to which this road subsegment belongs. For example, it is possible to look up the identification code in a previously established conversion table.The said conversion table stores a plurality of identification codes associated respectively with road segment identifiers and further stores, for each stored road segment identifier, identifiers of road sub-segments composing said road segment and the relative positions of said road sub-segments on said road segment. Thus, the received identification code (for example, a "Traffic Message Channel" code, . The TMC allows you to retrieve the associated road segment identifier (for example, stored in OpenLR format, as described previously) from the conversion table. The conversion table then retrieves the received road sub-segment identifier from among the stored road sub-segment identifiers describing the road sub-segments that make up the road segment associated with the received identification code. It also retrieves the relative position of the road sub-segment on that road segment. The relative position of the object on the road segment can then be determined by combining the relative position of the object on the road sub-segment with the relative position of the road sub-segment on the road segment associated with the received identification code.

[0073] Such a conversion table is, for example, established beforehand based on a list of location information received from a location information provider (e.g., a road traffic information provider, etc.). The location information provided includes a road sub-segment identifier and the relative position of the object on the road sub-segment (e.g., in OpenLR format), as well as an identification code (e.g., a TMC code) identifying a road segment larger than that of the road sub-segment. In such a case, it is possible to group together road sub-segment identifiers with the same identification code and combine them to form a road segment identifier, while preserving, for each road sub-segment, its relative position within the road segment described by the road segment identifier thus formed.The OpenLR format is particularly advantageous in that it allows for the easy combination of road sub-segment identifiers to form a road segment identifier.

[0074] More generally, it should be noted that the implementation and embodiment methods considered above have been described by way of non-limiting examples, and that other variants are therefore conceivable. References

[0075] [WOLTCHE2021] Adrian Wôltche, “Evolving map matching with Markov decision processes”, October 2021.

[0076] [OPENLR-VL5-REV2] OpenLR White Paper, “An open standard for encoding, transmitting and decoding location references in digital maps”, Version 1.5, Revision 2, https: / / download.tomtom.eom / open / banners / openlr-whitepaper_vl.5.pdf

Claims

1.

2. Demands Method (30) for positioning, by means of a processing device (20), an object on a target digital map (11) representing a road network, said method comprising: - a reception (S30) of location information for said object, said location information comprising or enabling the determination of a road segment identifier, said road segment identifier describing a road segment of the road network on which the object is located, and a relative position of said object on said road segment, - a search (S31) for the road segment identifier from the location information in a database associated with the target digital map, said database storing a plurality of road segment identifiers associated respectively with geometric models, each geometric model describing the geometry in the target digital map of the representation of the road segment described by the associated road segment identifier, - when the road segment identifier from the location information is present in the database: a determination (S32) of a map position (PC) of the object in the target digital map based on the geometric model (MG) associated in the database with said road segment identifier from the location information and based on the relative position of the object on the road segment. Method (30) according to claim 1, wherein, when the road segment identifier from the location information is absent in the database, the method comprises: - a search (S33), in the target digital map, for points representing the road segment described by the road segment identifier derived from the location information, - a determination (S34) of the object's position on the map as a function of the object's relative position on the segment road and according to the points representing the road segment in the target digital map.

3. Method (30) according to claim 2, wherein, when the road segment identifier from the location information is absent in the database, the method comprises: - determining a geometric model describing the points representing, in the target digital map, the road segment described by the road segment identifier from the location information, - storing, in the database, the road segment identifier from the location information in association with the determined geometric model.

4. A method (30) according to any one of the preceding claims, wherein the road segment identifier comprises at least two attributes of the road segment selected from the following list: - a geographical position of an end of the road segment, - a geographical position of a point of the road segment distinct from the ends of said road segment, - a road type of the road segment, - a length of the road segment, - a direction of travel on the road segment.

5. Method (30) according to any one of the preceding claims, wherein the relative position is representative of a distance measured along the road segment with respect to the geographical position of an end of said road segment.

6. Method (30) according to any one of the preceding claims, wherein the location information is formatted according to the OpenLR format.

7. Method (30) according to any one of the preceding claims, wherein the geometric model corresponds to a WKT character string or a WKB binary string.

8. A method (30) according to any one of the preceding claims, comprising a transmission of the determined map position to a display device of a vehicle and / or to an adaptive cruise control of said vehicle.

9. Method (30) according to any one of the preceding claims, wherein the map position of the object to be used by a vehicle carrying the target digital map, said object corresponds to said vehicle or to a point of interest for said vehicle.

10. Method (30) according to claim 9, wherein the processing device is remote from the vehicle or mounted in said vehicle.

11. A method (30) according to any one of the preceding claims, wherein the location information of said object comprises a road sub-segment identifier, a road segment identifier identification code and a relative position of said object on the road sub-segment, and the method comprises a determination of the road segment identifier and the relative position of said object on said road segment as a function of a conversion table storing a plurality of identification codes associated respectively with road segment identifiers and, for each stored road segment identifier, road sub-segment identifiers composing said road segment and relative positions of said road sub-segments on the road segment.

12. Product computer program comprising instructions which, when executed by a processing device comprising at least one memory and at least one processor, configure said processing device to implement a positioning method (30) according to any one of the preceding claims.

13. Computer-readable recording medium on which is recorded a set of instructions which, when executed by a processing device comprising at least one memory and at least one processor, configure said processing device to implement a positioning method (30) according to any one of claims 1 to 11.

14. A processing device (20) comprising at least one processor and at least one memory, configured to implement a positioning method (30) according to any one of claims 1 to 11

15. d 1 i. Vehicle (10) comprising a processing device according to claim 14.

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