Selecting a target vehicle for a driver assistance function

Abstract

The invention relates to a method for managing a driver assistance function of a motor vehicle comprising the following steps: - assigning (201) a risk level to the right and left of the current lane, the risk level being representative of the risk of crossing the lane boundaries; - determining (202) the position of at least one other vehicle in the vicinity of the motor vehicle, the position being associated with the right or left boundary; - determining (203) the proportion of the other vehicle present in the current lane; - deciding (204) whether (205) to select said other vehicle as the target vehicle for the driver assistance function, based on said determined proportion and the risk level associated with the boundary linked to the position of the other vehicle. FIG. 2

Description

Title of the invention: Selection of a target vehicle for a driver assistance function

[0001] The present invention belongs to the field of driver assistance in a motor vehicle, and relates in particular to driver assistance functions taking into account other vehicles circulating in the environment of the vehicle, called target vehicles.

[0002] The term "vehicle" means any type of vehicle such as a private, utility or heavy goods vehicle.

[0003] The term "driving assistance" for a vehicle refers to any method capable of assisting the driving of the vehicle. This method may consist of partially or fully steering the vehicle or providing any type of assistance to a person driving the vehicle. Driving assistance functions can relate to different levels of autonomy. The OICA (International Organization of Motor Vehicle Manufacturers) scale notably provides for six levels. Other scales exist to define the levels of autonomy enabled by driving assistance systems, such as the SAE (Society of Automotive Engineers) scale.

[0004] Thus, driving assistance covers functions of assistance to manual driving, for the lowest levels, such as levels 1 and 2 of the aforementioned scales, and autonomous vehicle piloting functions for the highest levels of autonomy.

[0005] Driver assistance systems, such as AD AS for "Advanced Driver-Assistance Systems", allow the driver of the vehicle to be assisted or even to fully control certain parameters of the vehicle's steering, such as longitudinal trajectory, speed in particular, and lateral trajectory, turning or changing lanes in particular.

[0006] These systems make it possible to improve driving comfort as well as safety, by taking advantage of data from vehicle sensors, such as radar or lidar data, cameras and / or geolocation devices.

[0007] Certain driving assistance functions, such as the ACC function in particular, for "Adaptive Cruise Control" in English, take into account the presence or absence of other vehicles in the vehicle's current lane of travel.

[0008] In the case where other vehicles are located in an adjacent lane of the current lane, it is difficult to anticipate whether the other vehicle will cross the boundary between the adjacent lane and the current lane, to move into the current lane in front of the vehicle.

[0009] Such uncertainty may lead the driving assistance function to brake when it is not necessary, or to fail to take into account the other vehicle, which may cause a collision.

[0010] There is therefore a need to improve both the safety and driving comfort of driver assistance functions taking into account other road users.

[0011] The present invention improves the situation.

[0012] To this end, a first aspect of the invention relates to a method for managing a driver assistance function of a motor vehicle comprising the following steps: - assignment of a risk level to the right of a current lane of the vehicle and / or a risk level to the left of the current lane, the risk level on the right being representative of a risk of crossing a right limit of the current lane and the risk level on the left being representative of a risk of crossing a left limit of the current lane; - determination of the position of at least one other vehicle in the environment of the motor vehicle, the position being associated with the right limit or the left limit; - determination of a proportion of said other vehicle present in the current lane; - decision to select or not the said other vehicle as the target vehicle for the driver assistance function, based on the said determined proportion and based on the level of risk associated with the limit associated with the position of the other vehicle.

[0013] Thus, it is made possible to anticipate more precisely the switching of another vehicle in the current lane, which improves driving comfort as well as the safety associated with the driving assistance function.

[0014] According to embodiments, the risk level on the right and the risk level on the left can be assigned based on vehicle sensor data.

[0015] Thus, different crossing risk levels can be determined for the left and right limits, which improves the accuracy associated with decision-making and consequently enhances the operation of the driver assistance function. Furthermore, the risk levels can be continuously updated.

[0016] Alternatively, the risk level on the right and the risk level on the left can be assigned based on map data stored by the motor vehicle.

[0017] Thus, different crossing risk levels can be determined for the left and right limits, which improves the accuracy associated with decision-making and consequently enhances the operation of the driver assistance function. Furthermore, the risk levels can be continuously updated.

[0018] According to some embodiments, the decision to select or not select said other vehicle as the target vehicle for the driver assistance function may to understand : - the determination of a threshold value based on the level of risk attributed to the limit associated with the position of the other vehicle; - the comparison of said determined proportion with the determined threshold value; - the selection of said other vehicle as the target for the driving assistance function, only if the determined proportion is greater than the threshold value.

[0019] Such decision-making is both precise and quick to execute for a control device equipped with computing resources. This allows for a high degree of responsiveness in implementing the selection of target vehicles, thereby improving the speed of implementation of the driver assistance function.

[0020] According to embodiments, the risk level on the right and the risk level on the left can be assigned from a set of several possible risk levels.

[0021] Thus, the determination of the level of risk is simplified, as the different driving situations can be determined in advance.

[0022] In addition, the set of several possible risk levels includes one or more of the following levels: - a first level of risk assigned to the right limit or the left limit when the current lane is limited by a roadside on the right or left; - a second level of risk assigned to the right limit or the left limit when the current lane is limited by a continuous line on the right or left; - a third level of risk attributed to the right limit or the left limit, when the current lane is limited by a broken line on the right or left; - a fourth level of risk assigned to the right or left boundary, when the current lane is joined on the right or left by an insertion lane.

[0023] Thus, it becomes possible to differentiate between several driving situations, encompassing all possible cases when driving the vehicle. The selection of target vehicles is therefore improved regardless of the driving situation.

[0024] In addition, each of the possible risk levels can be associated with a predefined threshold value.

[0025] Thus, the determination of the threshold value is simplified, which allows for a rapid selection of target vehicles for the driver assistance function.

[0026] In addition, a threshold value associated with the second risk level may be greater than a threshold value associated with the third risk level, and / or a threshold value associated with the third risk level may be greater than a threshold value associated with the fourth risk level.

[0027] Thus, the comparison is adapted to each driving situation, which improves the accuracy associated with the selection of target vehicles for the function driver assistance.

[0028] A second aspect of the invention relates to a computer program comprising instructions for implementing the method according to the first aspect of the invention, when these instructions are executed by a processor.

[0029] A third aspect of the invention relates to a motor vehicle control device, comprising a processor configured to: - assign a risk level to the right of a current lane of the vehicle and / or a risk level to the left of the current lane, the risk level on the right being representative of a risk of crossing a right limit of the current lane and the risk level on the left being representative of a risk of crossing a left limit of the current lane; - determining the position of at least one other vehicle in the environment of the motor vehicle, the position being associated with the right limit or the left limit; - determine a proportion of said other vehicle present in the current lane; - decide whether or not to select the said other vehicle as the target vehicle for the driver assistance function, based on the said determined proportion and based on the level of risk associated with the limit associated with the position of the other vehicle.

[0030] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings in which:

[0031] [Fig-1] illustrates a motor vehicle according to embodiments of the invention;

[0032] [Fig.2] is a diagram illustrating the steps of a process according to methods of implementation publication of the invention;

[0033] [Fig.3a] illustrates a motor vehicle according to embodiments of the invention, in a first driving situation;

[0034] [Fig.3b] illustrates a motor vehicle according to embodiments of the invention, in the second first driving situation;

[0035] [Fig.3c] illustrates a motor vehicle according to embodiments of the invention, in second or third driving situation;

[0036] [Fig.3c] illustrates a motor vehicle according to embodiments of the invention, in the second fourth driving situation;

[0037] [Fig.4] illustrates a motor vehicle according to embodiments of the invention, in a driving situation in which another vehicle is detected;

[0038] [Fig.5] illustrates a control device according to embodiments of the invention.

[0039] Figure 1 illustrates a motor vehicle 100, according to embodiments of the invention.

[0040] The vehicle 100 includes, in particular, a control device 101, which may be a centralized control device responsible for a plurality of vehicle functions. tomobile. The control device 101 can be of the ECU type in particular, for "Electronic Control Unit" in English.

[0041] The control device 101 can at least be responsible for selecting target vehicles for a driver assistance function implemented by a driver assistance module 102 of the vehicle, also called AD AS, for "Advanced Driver Assistance Systems". The AD AS module 102 is capable of implementing at least one driver assistance function based in particular on data from at least one sensor.

[0042] The vehicle 100 includes in particular a first sensor 105.1 which may be an image acquisition device, such as a camera capable of acquiring images of a scene in front of the vehicle 100. The image acquisition device 105.1 may be arranged in an upper part of a windshield of the vehicle 100.

[0043] The vehicle 100 may include at least one other sensor 105.N, and more generally Nl other sensors, N being an integer greater than or equal to 2. The at least one other sensor 105.N may be a radar or a lidar for example.

[0044] Based on data from one of the vehicle's sensors, the AD AS 102 module is capable of implementing at least a first function of controlling a lateral and / or longitudinal trajectory of the vehicle 100.

[0045] No restrictions are attached to vehicle 100, particularly regarding the level of driving autonomy permitted by the vehicle. The AD AS 102 module can assist the driver in piloting the vehicle, notably in determining or maintaining speed or acceleration, or can provide autonomous vehicle piloting without driver input. Driver assistance thus also encompasses automatic vehicle piloting.

[0046] According to the invention, at least one first driving assistance function implemented by the AD AS 102 module is a function capable of taking into account one or more target vehicles travelling on the same road as vehicle 100 or on an adjacent road.

[0047] Such consideration of a target vehicle may in particular take into account the position, speed, acceleration and / or direction of movement of the target vehicle.

[0048] The first function could, for example, be a function for adapting the vehicle's longitudinal speed, also called ACC, for "Adaptive Cruise Control". Other driver assistance functions that take into account a target vehicle can be implemented alternatively or in addition by the AD AS 102 module.

[0049] The vehicle 100 may further include a memory 103 capable of storing data used by the control device 101, by the ADAS module 102 and / or by any other module of the vehicle 100. The memory 103 may in particular store Map data, representative of a given territory or area encompassing the vehicle's current position. The map data can be updated remotely via a communication interface 106, which may be a cellular interface allowing the vehicle 100 to access a cellular network, such as a 3G, 4G, 5G, or any other generation network, for example. Thus, the vehicle 100 can obtain updated map data stored on a remote server.

[0050] The vehicle 100 may further include a satellite positioning module, such as GPS (Global Positioning System), capable of obtaining and maintaining the vehicle's current position.

[0051] Such a current position of the vehicle 100 can be overlaid by the control device 101 and / or by the ADAS module 102 with map data in order to locate the vehicle 100 within the surrounding road infrastructure. Such an overlay can be used by the ADAS 102 as input data for a driver assistance function. Furthermore, as described below, such an overlay can be used by the control device 101 when selecting the target vehicle for managing a driver assistance function according to the invention.

[0052] Fig. 2 is a diagram illustrating the steps of a process for managing a driver assistance function, according to embodiments of the invention.

[0053] At a step 200, the control device 101 obtains data representative of the current lane on which the vehicle 100 is traveling, in particular data relating to a type of right-hand and / or left-hand lane boundary. Such representative lane data may be obtained: - by superimposing the current position from the satellite positioning module 104 and the map data stored in memory 103 or obtained from a remote server. Indeed, such a superposition makes it possible to identify a type of right and / or left lane limit of the vehicle's current lane when the map data includes such details on the traffic lanes they represent; and / or - from sensor data, in particular data from the first 105.1 sensor capable of obtaining images or series of images representative of a scene facing the vehicle, i.e., directed towards a forward half of the vehicle. No restrictions are attached to the way in which the representative data of the current lane are derived from the image or series of images acquired by the first 105.1 sensor. Methods for identifying lines in images or series of images are known and are not further described herein.

[0054] Data representative of the lane can also be obtained from the other sensor 105.N, in particular when the other sensor 105.N is a radar or a lidar, capable of detecting when the right or left boundary is a road edge.

[0055] At a step 201, the control device 101 assigns a risk level to the right of the vehicle's current lane and / or a risk level to the left of the current lane, based on at least some of the data obtained at step 200, in particular based on the type of right-hand and left-hand lane boundary. The right-hand risk level represents a risk of crossing the right-hand lane boundary, and the left-hand risk level represents a risk of crossing the left-hand lane boundary.

[0056] For example, the risk level on the right and the risk level on the left can be assigned from a set of several possible, or predetermined, risk levels. The set of several possible risk levels may include one or more of the following levels: - a first level of risk assigned to the right limit or the left limit when the current lane is limited by a roadside on the right or left; - a second level of risk assigned to the right limit or the left limit when the current lane is limited by a continuous line on the right or left; - a third level of risk attributed to the right limit or the left limit, when the current lane is limited by a broken line on the right or left; - a fourth level of risk assigned to the right or left boundary, when the current lane is joined on the right or left by an insertion lane.

[0057] Risk levels can be compared with each other, particularly according to the degree of risk they represent. For example, the first risk level may be a "zero risk," meaning that the risk of crossing the right or left boundary associated with the first risk level is very low. Similarly, the second risk level may be a "low risk," the third risk level may be a "medium risk," and the fourth risk level may be a "high risk."

[0058] According to embodiments, in step 201, the control device 101 assigns two risk levels: a right risk level at the right limit of the running track and a left risk level at the left limit of the running track.

[0059] Figures 3a to 3d illustrate driving situations corresponding respectively to the four aforementioned risk levels.

[0060] Fig. 3a illustrates a vehicle 100 according to embodiments of the invention, in a first driving situation.

[0061] In the first driving situation, one of the limits of a running lane 300 in which the vehicle 100 is traveling is a roadside 301. In the case shown in [Fig.3a], it is a right-hand roadside 301 of the running lane 300. In this case, the risk of another vehicle crossing the roadside 301 from the right is zero and therefore corresponds to the first level of risk attributed to the right-hand limit of the running lane 300.

[0062] Fig. 3b illustrates vehicle 100 according to embodiments of the invention, in a second driving situation.

[0063] In the second driving situation, one of the limits of the running lane 300 in which the vehicle 100 is traveling is a solid line 311. In this case, it is the right-hand limit of the running lane 300. In this case, the risk of a vehicle crossing the solid line 311 from a lane 310 to the right of the running lane is low, and therefore corresponds to the second level of risk attributed to the right-hand limit of the running lane 300.

[0064] Fig. 3c illustrates vehicle 100 according to embodiments of the invention, in a third driving situation.

[0065] In the third driving situation, one of the limits of the running lane 300 in which the vehicle 100 is traveling is a broken line 321. In this case, it is the left-hand limit of the running lane 300. In this case, the risk of a vehicle crossing the broken line 321 from a lane 320 to the left of the running lane 300 is medium, and therefore corresponds to the third level of risk attributed to the left-hand limit of the running lane 300.

[0066] Fig. 3d illustrates vehicle 100 according to embodiments of the invention, in a fourth driving situation.

[0067] In the fourth driving situation, one of the boundaries of the main lane 300 in which the vehicle 100 is traveling is an oblique broken line 331 indicating that the main lane is joined by an on-ramp. In this case, it is the right-hand boundary of the main lane 300. Therefore, the risk of a vehicle crossing the broken line 331 to join the main lane 300 is high, and thus corresponds to the fourth risk level assigned to the right-hand boundary of the main lane 300.

[0068] Referring again to [Fig. 2], at a step 202, the control device 101 detects the position of at least one other vehicle relative to the current lane of the motor vehicle. The detection of such a position may be based on sensor data, such as sensors 105.1 and 105.N, or may be based on vehicle-to-vehicle communication, in particular V2V communication, or on communication with the road infrastructure, in particular V2I communication. V2V stands for Vehicle-to-Vehicle and V2I stands for Vehicle-to-Infrastructure. The detection may include identifying another vehicle in the vicinity of vehicle 100 and then identifying the position of that other vehicle relative to the current lane. Since such detection is known, it is not described further in this description.

[0069] Such position detection can in particular identify the limit of the current lane 300 of which the other vehicle is closest, among the right limit and the left limit. The vehicle thus detected is associated with the right limit or the left limit by the control device 101.

[0070] At a step 203, the control device 101 determines a proportion of the other vehicle present in the current lane of vehicle 100.

[0071] Such a proportion thus indicates: - if the other vehicle is entirely in the adjacent lane, on the other side of the boundary associated with the other vehicle. In this case, the proportion of presence in the current lane is equal to 0; - if the other vehicle is entirely within the lane. In this case, the proportion of presence within the lane is equal to 1; and - if the other vehicle is partially in the current lane, that is to say straddling its associated boundary. In this case, the proportion of presence is strictly between 0 and 1.

[0072] Figure 4 illustrates a motor vehicle according to embodiments of the invention, in a driving situation in which another vehicle 401 is detected in the environment of the vehicle 100.

[0073] More specifically, [Fig.4] illustrates the case where the other vehicle 401 is straddling one of the limits of the running lane 300, namely the right limit 400. The other vehicle 401 is thus partially in the running lane 300 and in zone 410 which may be an adjacent lane or a roadside.

[0074] The proportion of presence of the other vehicle 401 can be equal to the ratio of a first distance 402 to a second distance 403. The first distance 402 corresponds to the distance between the boundary 400 and the part of the other vehicle 401 in the current lane that is furthest from the boundary 400. The second distance can correspond to a lateral dimension of the other vehicle 401. A lateral dimension is a dimension normal to a principal direction of the current lane.

[0075] However, the aforementioned ratio is given for illustrative purposes only and no restrictions are attached to the manner of determining the proportion of presence in the current lane of the other vehicle 401.

[0076] At a step 204, the control device 101 determines, based on the proportion determined in step 203, and based on the level of risk assigned to the limit of the current lane to which the other vehicle is closest, whether the other vehicle is a target vehicle or not for the driver assistance function.

[0077] For this purpose, a set of rules can be applied by the control device 101 to the level of risk assigned to the limit associated with the other vehicle and to the determined proportion, the set of rules indicating at output whether the other vehicle is a target vehicle or not for the driving assistance function.

[0078] If this is the case, the control device 101 selects the other vehicle as The target vehicle is located at step 205, and returns to step 202 if a second vehicle is detected in the vicinity of vehicle 100. Otherwise, if no other vehicle is detected in the vicinity of vehicle 100, the process returns to step 200. The process can thus be iterated, allowing the target vehicle(s) to be updated based on changes in the current position of vehicle 100.

[0079] The selection step 205 of the other vehicle as the target vehicle may include the transmission of target information, identifying the other vehicle, to the AD AS 102 module, so that it takes into account the other vehicle as the target vehicle when implementing the first driver assistance function.

[0080] If this is not the case, that is, if the other vehicle is not selected as the target vehicle for the driver assistance function, the process returns to step 202 if a second other vehicle is near the current lane. Otherwise, if no other vehicle is detected in the vicinity of vehicle 100, the process returns to step 200. The process can thus be iterated, allowing the target vehicle(s) to be updated according to changes in the current position of vehicle 100.

[0081] The set of rules may include, in particular, comparing the proportion determined in step 203 for the other vehicle with a threshold value that depends on the risk level assigned to the edge of the current lane that is closest to the other vehicle. For example, if the other vehicle is closer to the right edge of the current lane, a threshold value is determined by the control device 101 based on the risk level assigned to the right edge of the current lane.

[0082] If the proportion determined in step 203 for the other vehicle is greater than or equal to the threshold value, then the other vehicle is selected as the target vehicle for consideration by the driver assistance function. Otherwise, the other vehicle is ignored and is not selected as the target vehicle for the implementation of the driver assistance function.

[0083] In what follows, an example of determining threshold values ​​is given by way of illustration.

[0084] For example, each risk level in the set of risk levels can be associated in a predetermined way with a given threshold value.

[0085] Thus: - the first level of risk is associated with a first threshold value; - the second level of risk is associated with a second threshold value; - the third risk level is associated with a third threshold value; and / or - the fourth risk level is associated with a fourth threshold value.

[0086] For example, the first threshold value could be equal to 0.25, or 25%. As a reminder, the first risk level corresponds to the situation in [Fig. 3a] where the limit of the current lane under consideration is a roadside. Therefore, any other A vehicle close to the roadside, and whose proportion of time spent in the current lane is less than 0.25, is not selected as a target. This is because it is likely that the other vehicle is stopped, for example, parked on the roadside. Conversely, any other vehicle close to the roadside and whose proportion of time spent in the current lane is greater than or equal to 0.25 is selected as a target vehicle. Since there is no traffic lane on the other side of the roadside, it is likely that the vehicle is traveling in the current lane, although partially on the roadside.

[0087] Preferably, the second threshold value is greater than the third threshold value, which is greater than the fourth threshold value.

[0088] For example, the second threshold value is equal to 0.75, or 75%, the third threshold value is equal to 0.5, or 50%, and the fourth threshold value is equal to 0.25, or 0.25%. In this case, the fourth threshold value is equal to the first threshold value. Alternatively, the first and fourth threshold values ​​may be different.

[0089] Thus, in the second driving situation of [Fig.3b], associated with a low risk of insertion, if the other vehicle is close to the right limit 311 of the current lane, its proportion of presence is compared to 0.75, and, if it is greater than or equal to 0.75, then the other vehicle is selected as the target vehicle.

[0090] In the third driving situation of [Fig.3c], associated with a moderate risk of insertion, if the other vehicle is close to the left limit 321 of the current lane 310, its proportion of presence is compared to 0.50, and, if it is greater than or equal to 0.50, then the other vehicle is selected as the target vehicle.

[0091] In the fourth driving situation of [Fig.3d], associated with a high risk of insertion, if the other vehicle is close to the right limit 331 of the current lane 310, its proportion of presence is compared to 0.25, and, if it is greater than or equal to 0.25, then the other vehicle is selected as the target vehicle.

[0092] Figure 5 shows the structure of a control device 101 according to modes of realization of the invention.

[0093] The control device 101 includes a processor 501 configured to communicate unidirectionally or bidirectionally, via one or more buses or via a direct wired connection, with a memory 502 such as a Random Access Memory (RAM), a Read Order Memory (ROM), or any other type of memory (Flash, EEPROM, etc.). Alternatively, the memory 502 comprises several memories of the aforementioned types.

[0094] The memory 502 is capable of storing, permanently or temporarily, at least some of the data used and / or resulting from the implementation of the process described with reference to [Fig.2].

[0095] In particular, memory 502 can store the aforementioned associations between values threshold and risk levels, as well as a set of at least one rule whose application indicates whether another vehicle is a target vehicle or not for the driver assistance function.

[0096] The processor 501 is capable of executing instructions, stored in memory 502, for the implementation of the steps of the process according to the invention, described with reference to [Fig. 2]. Alternatively, the processor 501 can be replaced by a microcontroller designed and configured to perform the steps of the process according to the invention, described with reference to [Fig. 2].

[0097] The control device 101 includes a first interface 503 capable of obtaining data during step 200, from the sensor(s) 105.1 and 105.N, the memory 103 of the vehicle 100, the GPS module 104 and / or the communication module 106.

[0098] The control device 101 may further include a second interface 504 capable of communicating with the AD AS module 102, in particular to indicate to it the vehicle or vehicles selected as target vehicles.

[0099] The control device 101 may include other interfaces for communicating with other equipment of the vehicle 100.

[0100] The present invention is not limited to the embodiments described above by way of example; it extends to other variants.

Claims

Claims

1. Method for managing a driving assistance function of a motor vehicle (100) comprising the following steps: - allocation (201) of a risk level to the right of a current lane (300) of the vehicle and / or a risk level to the left of the current lane, the risk level to the right being representative of a risk of crossing a right limit (301; 311; 331) of the current lane and the risk level to the left being representative of a risk of crossing a left limit (321) of the current lane; - determination (202) of a position of at least one other vehicle (401) in the environment of the motor vehicle, the position being associated with the right limit or the left limit; - determination (203) of a proportion of said other vehicle present in the current lane;- decision (204) to select (205) or not said other vehicle as target vehicle for the driving assistance function, depending on said determined proportion and depending on the risk level associated with the limit associated with the position of the other vehicle.;

2. The method of claim 1, wherein the right risk level and the left risk level are assigned based on sensor data (105.1; 105.N) of the vehicle (100).

3. The method of claim 1, wherein the right risk level and the left risk level are assigned based on map data stored by the vehicle (100).

4. Method according to one of the preceding claims, wherein the decision (204) to select (205) or not said other vehicle (401) as the target vehicle for the driving assistance function comprises: - determining a threshold value as a function of the risk level attributed to the limit associated with the position of the other vehicle; - comparing said determined proportion with the determined threshold value; - selecting said other vehicle as the target for the driving assistance function, only if the determined proportion is greater than the threshold value.

5. A method according to any preceding claim, wherein the right risk level and the left risk level are assigned among a set of several possible risk levels.

6. Method according to claim 5, wherein the set of several possible risk levels comprises one or more of the following levels: - a first risk level assigned to the right limit or the left limit when the current lane (300) is limited by a roadside (301) on the right or on the left; - a second risk level assigned to the right limit or the left limit when the current lane is limited by a continuous line (311) on the right or on the left; - a third risk level assigned to the right limit or the left limit, when the current lane is limited by a broken line (321) on the right or on the left; - a fourth risk level assigned to the right limit or the left limit, when the current lane is joined on the right or on the left by an insertion lane (410).

7. A method according to claim 4 and claim 5 or 6, wherein each of the possible risk levels is associated with a predefined threshold value.

8. The method of claims 6 and 7, wherein a threshold value associated with the second risk level is greater than a threshold value associated with the third risk level, and / or a threshold value associated with the third risk level is greater than a threshold value associated with the fourth risk level.

9. Computer program comprising instructions for implementing the method according to one of the preceding claims, when these instructions are executed by a processor (501).

10. Control device (101) for a motor vehicle (100), comprising a processor (501) configured to: - assign a risk level to the right of a current lane (300) of the vehicle and / or a risk level to the left of the current lane, the risk level to the right being representative of a risk of crossing a right limit (301; 311; 331) of the current lane and the risk level to the left being representative of a risk of crossing a left limit (321) of the current lane; - determine a position of at least one other vehicle (401) in the environment of the motor vehicle, the position being associated with the right limit or the left limit; - determine a proportion of said other vehicle present in the current lane; - decide whether or not to select the said other vehicle as the target vehicle for the driving assistance function, depending on the said determined proportion and depending on the level of risk associated with the limit associated with the position of the other vehicle.

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