WO2017168013A1

WO2017168013A1 - Method and system for lane-changing assistance for a motor vehicle

Info

Publication number: WO2017168013A1
Application number: PCT/EP2017/057894
Authority: WO
Inventors: Xavier Groult; Gaetan LE-GALL
Original assignee: Valeo Schalter Und Sensoren Gmbh
Priority date: 2016-04-01
Filing date: 2017-04-03
Publication date: 2017-10-05
Also published as: FR3049560A1; FR3049560B1

Abstract

The invention relates to a method for lane-changing assistance for a motor vehicle (2) from an initial driving lane (L₁) to an end driving lane (L₂), the method comprising a step of detecting the end driving lane (L₂), and a step of guidance of the motor vehicle (2) so that it joins the end driving lane (L₂) over a predetermined lane-changing interval. According to the invention, the method also comprises a step of determining at least one parameter characteristic of the driving behaviour of a driver of said motor vehicle (2), and said lane-changing interval is pre-determined and fixed according to said at least one parameter.

Description

METHOD AND SYSTEM FOR ASSISTING THE CHANGE OF THE RUNWAY FOR VEHI CULE AUTOMOBI LE

The present invention generally relates to motor vehicles equipped with semi-automatic or even automatic driver assistance systems, and more specifically assistance systems for the change of driving lane for a motor vehicle.

Such lane change systems, known as LCC (English initials set for Lane Change Control), aim to control, by acting on the control members of the steering of the vehicle or the braking system, the path followed by a motor vehicle when it is necessary to change the driving lane, for example when passing another vehicle or after passing a vehicle.

Such systems generally use information from a road mark detector, such as an on-board camera at the front of the vehicle, to identify the lateral limits not only of the track on which the vehicle is traveling, but also lanes adjacent to the current taxiway. When the vehicle is in a situation where a change of lane, from an initial taxiway to a final taxiway, is possible, the conventional systems generally calculate the central trajectory of the final taxiway, and determine from information from a vehicle location system, for example a navigation system, and vehicle speed and / or acceleration information, a trajectory that must be followed by the motor vehicle to make it reach the central trajectory of the final taxiway. The conventional systems then control the vehicle so that it follows this path automatically until reaching the central path of the final taxiway.

By way of example, FIG. 1 shows a driving situation on a road 1, for example a motorway, comprising, within two extreme lateral limits 10 and 11, three possible taxiways. L-I, I 2 and I 3 in the same direction of travel, each being delimited by two marking lines on the ground, such as the marking line 13. A motor vehicle 2 equipped with a lane-changing assistance system is represented traveling on the taxiway l_i located here the rightmost of the road 1 in the direction of the traffic. The motor vehicle 2 follows in the example a third vehicle 3 that it is about to overtake using the lane assistance system. For the sake of simplification, it is assumed that the system has already identified the initial taxiway, here the Li track, the final taxiway, here the L ₂ lane, and that the lane change is indeed possible (ground marking authorizing the change of lane, no third-party vehicle on the final taxiway likely to hinder the overtaking, for example a third-party vehicle located at the rear of the vehicle 2). In this case, a conventional lane-assisting system will determine the central trajectory L _c of the final taxiway L ₂ and then determine the trajectory P to be followed by the vehicle 2 to bring the vehicle onto the trajectory central L _c .

The lane change maneuver is usually initiated after the driver or system has verified that a lane change was possible, and that the driver has activated the direction indicator. The duration T necessary to allow the motor vehicle 2 to join the central path L _c is fixed, generally of the order of 5 seconds.

Such systems do not always give a feeling of safety for the driver. In particular, some drivers of calm nature will find that the maneuver is too fast, while other drivers, with more aggressive driving, will instead consider that the maneuver is too slow compared to what they would have done them -Same.

Also known from US 2012/0215415 a driving assistance system that uses a determination of at least one characteristic parameter of the acceleration behavior of a driver of the motor vehicle. The system is then able to regulate the speed of the vehicle according to this parameter. Lane change procedures are not supported by the system described. The invention aims to overcome the disadvantages and limitations of known systems by providing a change of lane assistance that tends to approach the natural behavior of a motorist and to increase accordingly his sense of security.

To do this, the subject of the present invention is a lane-assisting method for a motor vehicle from an initial taxiway to a final taxiway, the method comprising a step of detecting the final taxiway, and a control step of the motor vehicle so that it rejoins the final taxiway in a predetermined lane change time, characterized in that it further comprises a step of determining at least one characteristic parameter of the behavior of the vehicle. driving a driver of said motor vehicle, and in that said lane changeover time is predetermined and set according to said at least one parameter.

The characteristic parameter of the driving style of a driver may for example be related to accelerations / decelerations made by a driver.

Alternatively or in combination, the driving style can also be determined from other measurements, for example by steering angle tracking (steering angle) when a driver manually makes a lane change.

In addition, some known systems alert the driver or prevent the automatic lane change maneuver, when traffic conditions do not allow it. Figure 2 illustrates the surveillance areas close to the motor vehicle 2 that allow such systems to offer this functionality. For the sake of simplicity, only the surveillance zones located in the left lane with respect to the driving lane of the motor vehicle 2 have been represented, but it is easily understood that similar zones are provided on the right side of the motor vehicle 2. first surveillance zone shown in FIG. 2, at the height of the motor vehicle 2, forms a zone Ai called the security zone which makes it possible to prevent any automatic change of lane when a third vehicle is detected as being present in this zone . The length the area Α-ι, taken in the direction of travel, is predefined relative to the front and rear of the motor vehicle 2 and therefore also takes into account the length of the motor vehicle 2. In the example shown, this zone Ai extends over 12 meters with respect to the front of the vehicle 2, and 3 meters with respect to the rear of the vehicle 2. The width of the zone Ai is also defined as being at least the width of the final taxiway (typically of the order of 3.5 meters for a motorway in France), preferably increased by a safety margin, for example of the order of 0.5 meters, encroaching on the taxiway of motor vehicle 2, to advantageously account for two-wheel vehicles likely to roll between the two lanes.

A second zone A ₂ , forming a rear surveillance zone, is also observed by appropriate components of the system (cameras, radars ...). This zone A ₂ , which starts immediately behind the safety zone Ai, may have a width identical to the safety zone Ai, and a predefined length, fixed in the example to 67 meters. The observation of this rear surveillance zone makes it possible to give a lane change authorization under certain conditions only. The principle is as follows: the lane change is authorized by the system if no third vehicle has been detected as present in zone A ₂ . If, however, as shown in Figure 2, a third vehicle is detected on the final taxiway, as occurring at the rear of the vehicle 2, the system will estimate, from a determination of the positions and relative speeds of the vehicle. detected third vehicle and the vehicle 2, a TTC duration (English initials set for Time To Collision) corresponding to the time that would elapse until a collision between the motor vehicle 2 and the third vehicle detected in the case where the system authorize the overrun. A first TTCt -re threshold, for example set at 5 seconds, will serve as a comparison value with the estimated TTC duration to allow or not the change of lane. More specifically, a change of lane will be authorized if the duration

Estimated VAT is higher than the first threshold TTC _t - _r e _> and prohibited in the opposite case. Some more sophisticated systems do the same for traffic monitoring in a third zone A ₃ , forming a front surveillance zone. This zone A ₃ , which starts immediately ahead of the safety zone Ai, may have a width identical to the safety zone Ai, and a predefined length, fixed in the example to 58 meters. Similarly to what has been described for the rear surveillance zone A ₂ , for any third vehicle detected in this zone A ₃ , it is estimated that a duration TTC that is compared to a second threshold TTCth-fr, fixed for example at 7 seconds. The automatic lane change maneuver will be authorized if the estimated TTC duration is greater than the second TTCth-fr threshold, and prohibited in the opposite case.

To correspond to this type of systems, and according to other possible aspects of the process:

the method may further comprise a step of monitoring a safety zone situated on the final taxiway, on one side of the motor vehicle, so as to prohibit any change of lane in the event of detection of the presence of a vehicle thirds in this security zone;

said safety zone extends over a predetermined length as a function of the length of the motor vehicle, a predefined front safety distance from the front of the motor vehicle, and a predefined rear safety distance from from the rear of the motor vehicle;

advantageously, said safety distance before and / or said rear safety distance also varies according to said at least one characteristic parameter of the driving behavior of a driver of said motor vehicle;

the method preferably also comprises a step of monitoring at least one surveillance zone located on the final taxiway, at the front or rear of said safety zone, comprising a preliminary sub-step of receiving a detection information of a third-party vehicle present in said at least one monitoring zone, for determining the relative position and speed of said motor vehicle and the detected third-party vehicle, for estimating a corresponding TTC duration at a time that would elapse until a collision between said motor vehicle and the vehicle detected third party, and comparing the estimated TTC duration to a threshold value, and the lane change is prohibited if the estimated TTC duration is less than said threshold value;

- Again, said threshold value may advantageously vary according to said at least one characteristic parameter of the driving behavior of a driver of said motor vehicle;

said at least one surveillance zone is for example a rear surveillance zone associated with a rear threshold value TTCL th-re. It is also possible to provide a monitoring zone before, associated with a threshold value before TTC ^ _ ^. A complete system will advantageously combine the front and rear surveillance zones;

said determining step comprises a sub-step of classifying a driver in one of a plurality of representative categories of driving behavior according to said at least one parameter, and the lane change duration T is set to a value belonging to at an interval between a minimum duration T _min and a maximum duration T _max , the minimum duration T _min and the maximum duration T _max depending on the category.

The invention also relates to a lane-assisting system for a motor vehicle from an initial taxiway to a final taxiway, the system comprising means for detecting the final taxiway, and means for controlling the motor vehicle so that it rejoins said final taxiway in a predetermined lane changeover time, characterized in that it furthermore comprises means for determining at least one characteristic parameter of the driving behavior of a driver of said motor vehicle, and in that said control means are adapted to set said lane change time according to said at least one parameter. The invention and the various advantages that it provides will be better understood from the following description, made with reference to the appended figures, in which:

FIG. 1, already described above, describes an example of a taxi situation involving a lane change made with a known lane change assistance system;

FIG. 2, already described above, illustrates various surveillance zones that can be examined in the context of a lane change authorization;

FIG. 3 represents, in the form of a simplified block diagram, a possible general architecture of a lane departure assistance system capable of implementing the method according to the invention;

- Figure 4 schematically illustrates steps of a lane change assistance method.

In the rest of the description, and unless otherwise stated, the elements common to all the figures bear the same references.

FIG. 3 is a simplified illustration of an on-board lane-assist system 4 for a motor vehicle from an initial taxiway to a final taxiway. In the nonlimiting example shown in this figure, the system 4 cooperates with other elements present on the vehicle, in particular with a road marking line detector 5, for example a camera located at the front of the motor vehicle, a system 6 for locating the motor vehicle, for example a GPS-type navigation receiver, and various sensors 7 making it possible to determine the current speed and / or the acceleration of the motor vehicle. The system 4 also cooperates with a system 8 for checking the steering column of the vehicle, or even with a braking system (not shown). It should be noted that the detector 5 could also be integrated into the system 4 without departing from the scope of the present invention. The system comprises, in a preferred version, a set 9 of sensors (cameras, radars, lidars ...) allowing the monitoring of different zones in the environment close to the motor vehicle 2, such as the safety zone Ai, and the rear surveillance zones A ₂ or before A ₃ described above, for the detection of the presence of one or more third vehicles.

The reference 40 in FIG. 2 represents means for detecting the possible taxiways at the front of the vehicle, and in particular the initial taxiway and the final taxiway. These means 10, for example in the form of a dedicated processing module, receive the information from the detector 5, in this case the images captured by the camera, and extract from this information the road marking lines of the various tracks located at the front of the camera. vehicle, including the final taxiway for the change of lane defined laterally by two marking lines. Different processing algorithms exist to allow the detection of possible rolling paths, and do not need to be further detailed because without affecting the method according to the invention.

The system 4 also conventionally comprises means 41 for determining a central trajectory L _c with respect to the final taxiway that has been detected, as well as means 42 for controlling the motor vehicle so that it rejoins the central trajectory L _c . The central trajectory L _c is for example determined from the detection of two road marking lines laterally delimiting the detected final taxiway.

The control means 42 are particularly capable of determining a trajectory to be followed by the motor vehicle 2 to go from the initial taxiway to the final taxiway by joining the central trajectory L _c (trajectory P in FIG. to act on the control system 8 of the steering column of said motor vehicle, or even on the braking system, to guide the car automatically during the lane change maneuver.

In the following, the following variables are defined:

Xj is the initial position of the motor vehicle 2;

- Xf is the final position of the motor vehicle 2;

- Vj is the initial speed of the motor vehicle 2; Vf is the final speed of the motor vehicle 2;

Aj is the initial acceleration of the motor vehicle 2;

Af is the final acceleration of the motor vehicle 2;

T represents the time required to operate the lane change maneuver.

The trajectory that the motor vehicle must follow is predefined and obeys the following order 5 polynomial function:

Χ (ί) = 3 ₅ ί ⁵ ₊ 3 ₊ ₃₃ ί ³ + ¾ί ² _{+ 3ι} ί ₊ ¾

in which the duration T is the input data and with: = V

As indicated in the introduction, the systems of the prior art use a fixed duration T, of the order of 5 seconds.

In a different way, the invention provides for determining beforehand at least one characteristic parameter of the driving behavior of a driver of the motor vehicle 2, and of varying at least the duration T of the lane change as a function of this parameter.

The determination of the characteristic parameter of the driving behavior of the driver can be done according to the teachings of US 2012/0215415, observing the acceleration / deceleration performed by the driver. For example, comparison thresholds and speeds or accelerations of the vehicle 2 are used to categorize the behavior. of a driver in several, for example in three categories, a first category corresponding to a driver "quiet", a second category corresponding to a driver "normal", and a third category corresponding to a driver "aggressive".

Other methods can be used in addition or alternatively to characterize a specific conduct behavior to the change of way:

- measurement of one or more of the following parameters: steering angle, lateral speed, lateral acceleration, yaw rate and / or flying torque during several manual lane changes. The measurements are then compared with typical curves or values corresponding to the desired behaviors (calm, nominal, abrupt ...);

- measurement of the average lane change time in manual. In a basic implementation of the invention, for the duration T of the automatic lane change maneuver, a value of the order of 6.5 seconds is used for the "normal" drivers, whereas this value T will be more low (typically of the order of 4.5 seconds) for "aggressive" drivers who would naturally tend to operate more quickly a change of lane, and that this value T will be larger (typically of the order of 7 seconds) for "quiet" drivers who would naturally tend to operate a lane change more slowly.

In a more complex implementation of the invention, in which the assistance system comprises means capable of monitoring zones on the side, front and / or rear of the vehicle 2 (typically cameras, radars). and / or lidars embedded on the vehicle 2, generally represented by the reference 9 in FIG. 3, it is also considered that the characteristic parameter of the driving behavior of a driver of the motor vehicle 2 will advantageously be able to be used to modify the conditions enabling to authorize or not a change of lane, in the case of detections of the presence of a third vehicle in one of the surveillance zones A ₁ , A ₂ or A ₃ described above with reference to FIG. 2. With regard to the Ai safety zone, the principle is to increase the front and / or rear safety distances for "quiet" drivers, and to reduce the same front and / or rear safety distances for "aggressive" drivers ". In other words, the quieter the driver, the longer the safety zone Ai.

With regard to the A ₂ rear surveillance zone or the A ₃ surveillance zone, the principle is to increase the value of the TTC _thre stern threshold, respectively before TTC _{th fr} for "quiet" drivers, and reduce this same threshold value TTC ^ _ respectively before TTC _{th fr} for "aggressive" drivers. In other words, the more aggressive the driver, the lower the TTC ^ _, respectively before TTC _{th fr} , threshold values are low, thus reflecting much better the behavior of this type of drivers.

In a preferred embodiment, for each class of conductors, two limit values are defined.

"T. and

mm T for the ^ max ^ duration T required for a lane change maneuver.

Table 1 below gives an example of the different values that can be adopted in a lane-assist system according to the present invention, depending on the category of the driver.

Duration Duration

Value Value Maximum minimum distance

security threshold

Category of

front rear front / rear drivers change change

TTC t ,, h-re Track lane area

Zone A3 security Ai

Zone A2 T m .m T max

Quiet 8s 6s 7,5s 8s 15s / 5s

Normal 7 s 5 s 5.5 s 7.5 s 12 m / 3 m

Aggressive 4.5 s 4 s 4 s 5.5 s 10 m / 2 m

Table 1

5 For each class of driver, how to determine the duration

T necessary for the change of lane preferably obeys the following rules (assuming of course that no third vehicle has been detected in the safety zone A1, which would in this case prohibit any change of lane maneuver), so as to have a duration adapted to the traffic conditions:

- If at least one TTC duration estimated for a third-party vehicle detected in any of the A2 or A3 forward surveillance zones is substantially equal to the threshold value corresponding to the surveillance zone considered (TTC ^ for Surveillance Zone A ₂ and TTC _{th fr} for the Surveillance Zone A ₃ ), then we find ourselves in a situation in which the lane change maneuver should last as short as possible. In this case, the duration T is set equal to the minimum duration T _m j _n . - If, on the contrary, all estimated times TTC are higher than the threshold value of the surveillance zone considered, increased by a margin of safety, then one finds oneself in a situation in which the maneuver of lane change can last longer . In this case, the duration T is set equal to the maximum duration T _max . The safety margin is for example given by the difference between T _max and T _m j _n .

- In all other cases which are intermediate, that is to say if all the estimated durations TTC are between the threshold value of the surveillance zone considered, and this threshold value increased by the safety margin, the duration T must be set to a value between the minimum duration Tmin and the maximum duration Tmax, defined for example according to the following relation:

T = min ( ^v TTC TTC t, hf _t r + T m .m, 'TTC re-TTC t, h-re + T m .m;' T max) 'in which TTC _fr is an estimated duration for a third vehicle detected in the area before A ₃ , and TTC _re is an estimated time for a third vehicle detected in the rear area A ₂ .

FIG. 4 summarizes the steps of a lane-assisting method for a motor vehicle from an initial taxiway to a final taxiway according to the present invention, in its most elaborate form:

The method starts with a step 100 of detection of the final taxiway, for example by the processing of the images captured by a camera 2 for extracting the road marking lines located at the front of the vehicle.

The method then continues with a step 110 of determining at least one characteristic parameter of the driving behavior of a driver of the motor vehicle 2, allowing the classification of the driver in one of several categories. Step 120 corresponds to the monitoring of the security zone A- | The lane change procedure terminates without a lane change if a third vehicle is detected in this A- | safety zone. As seen above, the length of the surveillance zone is preferably adapted to the type of conductor.

Step 130 corresponds to the monitoring of the rear monitoring zone A ₂ and / or before A _3. The lane departure procedure ends without a lane change if a third vehicle is detected in one of these zones. zones, for which the estimated TTC duration is less than the threshold value of the surveillance zone considered. As seen above, the threshold values are also preferably adapted to the type of conductor.

The last step 140 represented corresponds to the step of controlling the motor vehicle 2 so that it rejoins the final driving lane L ₂ in a lane change time T, defined, in accordance with the invention, with the type of conductor.

Claims

Lane change assisting method for a motor vehicle (2) from an initial taxiway (Li) to a final taxiway (L ₂ ), the method comprising a step (100) for detecting the taxiway final stage (L ₂ ), and a step (140) for controlling the motor vehicle (2) so that it rejoins the final driving lane (L ₂ ) in a predetermined lane change duration (T), characterized in that it further comprises a step (110) for determining at least one parameter characteristic of the driving behavior of a driver of said motor vehicle (2), and in that said lane change duration (T) is predetermined and set according to said at least one parameter.

A method according to claim 1, characterized in that it further comprises a step (120) for monitoring a safety zone (Ai) situated on the final taxiway (L ₂ ) on one side of the motor vehicle ( 2), so as to prohibit any change of lane in the event of detection of the presence of a third-party vehicle in this safety zone.

A method according to claim 2, characterized in that said safety zone (Ai) extends over a predetermined length as a function of the length of the motor vehicle (2), a predefined forward safety distance from the front of the motor vehicle (2), and a predefined rear safety distance from the rear of the motor vehicle (2).

Method according to claim 3, characterized in that said safety distance before and / or said rear safety distance varies according to said at least one characteristic parameter of the driving behavior of a driver of said motor vehicle (2). Method according to any one of claims 2 to 4, characterized in that it further comprises a step (130) for monitoring at least one surveillance zone (A ₂ , A ₃ ) located on the final taxiway (L ₂ ), at the front or rear of said security zone (Ai), comprising a preliminary step of receiving a detection information of a third vehicle (3 '; 10) present in said least one monitoring zone (A ₂ , A ₃ ), determining the relative position and speed of said motor vehicle (2) and the detected third vehicle, estimating a duration TTC corresponding to a time which would flow to a collision between said motor vehicle (2) and the detected third-party vehicle, and to compare the estimated TTC duration to a threshold value, and that the lane change is prohibited if the estimated TTC duration is less than said threshold value.

Method according to claim 5, characterized in that said threshold value varies according to said at least one characteristic parameter of the driving behavior of a driver of said motor vehicle (2).

Method according to any one of claims 5 or 6, characterized in that said at least one surveillance zone is a rear surveillance zone (A ₂ ) ^; associated with a rear threshold value TTQ t, h-re

Method according to any one of claims 5 or 6, characterized in that said at least one monitoring zone is a front monitoring zone (A ₃ ) associated with a threshold value before TTC ^ ^.

A method as claimed in any one of claims 5 to 8, characterized in that said determining step (110) includes a sub-step of classifying a driver into one of a plurality of representative categories of driving behaviors as a function of said least one parameter, and in that the channel change duration (T) is set to a value belonging to an interval between a minimum duration T _min and a maximum duration T _max , the minimum duration T _min and the maximum duration T _max depending on the category.

10. Method according to any one of the preceding claims, characterized in that said at least one parameter comprises accelerations / decelerations of the vehicle.

11. Method according to any one of the preceding claims, characterized in that said at least one parameter comprises steering angle measurements at the change of lanes.

12. Lane guidance system for a motor vehicle (2) from an initial taxiway (Li) to a final taxiway (L ₂ ), the system comprising track detection means (40) of final driving (L ₂ ), and means (42) for controlling the motor vehicle (2) so that it rejoins said final taxiway (L ₂ ) in a predetermined lane change duration (T), characterized in that it further comprises means for determining at least one parameter characteristic of the driving behavior of a driver of said motor vehicle (2), and in that said means (42) of control are able to set said duration (T) of change of lane according to said at least one parameter.

13. The system of claim 10, characterized in that the means (40) for detecting the final taxiway are adapted to receive images captured by an onboard camera (5).

14. System according to any one of claims 10 to 11, characterized in that the means (42) for controlling the motor vehicle (2) are able to act on a system (8) for controlling the steering column of said vehicle. automobile (7), or even on a braking system.