FR3051274A1 - DRIVING ASSISTANCE SYSTEM WITH DETERMINATION OF ROAD MARKING LINES IN THE FRONT OF A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a driving assistance method for a motor vehicle (1) moving on a taxiway, in which marking lines are determined at the front of the motor vehicle (1) delimiting said taxiway , and it is estimated a distance separating the motor vehicle (1) from said marking lines at the front of the motor vehicle (1). According to the invention the marking lines at the front of the motor vehicle (1) are determined by performing an extraction of marking lines (3rest, 4rest) at the rear of the motor vehicle from images captured by a camera (5) located at the rear of the motor vehicle (1), then a modeling of the marking lines (3fest, 4fest) at the front from the marking lines (3rest, 4rest) extracted at the rear of the motor vehicle (1).

Description

DRIVING ASSISTANCE SYSTEM WITH DETERMINATION OF ROAD MARKING LINES TO THE FRONT OF A VEHI CULE

AUTOMOBI LE

The present invention relates generally to motor vehicles equipped with automatic and / or semi-automatic assistance systems for driving, and more specifically systems requiring the detection of road marking lines present at the front of a motor vehicle. when it moves.

Many driving assistance systems are now proposed to improve traffic safety conditions. Among the possible functionalities, known including Lane Departure Warning systems or Lane Departure Warning (English terminology) to alert the driver when the vehicle is on the road. not to deviate from its trajectory, typically the taxiway on which it is located. Other systems, known in the English terminology of "Lane Keeping Assistance Systems" go even further by allowing the vehicle to automatically maintain its trajectory within its driving lane.

All these systems are based on the use of a camera placed at the front of the vehicle, for example at the level of the windshield or the front bumper, or even two cameras located on the front sides of the vehicle, for example at the front of the vehicle. level of mirrors. A real-time processing of the images captured by the camera or cameras makes it possible to extract, by different recognition algorithms, the marking lines on the ground at the front of the vehicle, and to estimate consequently the distance of the vehicle to these lines. marking. Depending on the vehicle odometry parameters (speed, acceleration ...), it is possible to anticipate a trajectory deviation or even a crossing of lines, and to act accordingly (alert and / or automatic correction of trajectory) .

However, the obligation to use one or more front cameras dedicated solely to the detection of marking lines, often in addition to other sensors already present on the vehicle and assigned to other assistance features, such as radar or lidars, is a brake on the development of such systems in terms of cost.

In addition, most motor vehicles are now equipped with a rear camera that can be used in several safety features such as parking assistance, detection of pedestrians or obstacles during a maneuver in reverse, etc ...

US 8,385,600 discloses a system in which a camera placed at the rear of a vehicle captures images and transmits them in real time to a road type detection system (Fig. 2 of US 8, 385, 600) suitable for determining in particular the type of marking lines on the ground and the crossing of a marking line. The road type detection system transmits its data to another system capable of estimating in particular the taxiway used by the vehicle (FIG. 3 of US 8,385,600). Such a system is however not usable for the above-described functionalities of automatically maintaining the vehicle in the taxiway and / or warning the driver if there is a risk of accidental crossing of the line. Indeed, such features require to know the marking lines located at the front of the vehicle, so as to anticipate a possible accidental crossing line or control the maintenance of the path of the vehicle in its driving lane.

The object of the present invention is to propose a method and a system for detecting marking lines delimiting a taxiway of the vehicle on the basis of images captured by a rear camera which are equally powerful, in particular in terms of anticipation, that a method and system using a camera at the front of the vehicle, so as to allow a function of maintaining a trajectory in a taxiway and / or warning when crossing lines involuntarily.

To do this, the subject of the present invention is a driving assistance method for a motor vehicle traveling on a taxiway, comprising a step of determining marking lines at the front of the motor vehicle delimiting said track. rolling and a step of estimating a distance separating the motor vehicle from said marking lines at the front of the motor vehicle, characterized in that the step of determining the marking lines at the front of the motor vehicle comprises a step of extracting marking lines at the rear of the motor vehicle from images captured by a camera located at the rear of the motor vehicle, and a substep of modeling the marking lines at the front to from the marking lines extracted at the rear of the motor vehicle.

According to other possible aspects of the method: the sub-step of extracting marking lines at the rear of the motor vehicle is preferably followed by a substep of determining a radius of curvature of the marking lines extracted in the back; the substep of modeling the marking lines at the front can then comprise the estimation of a plurality of possible radii of curvature for the marking lines at the front, from said determined radius of curvature; - Said plurality of possible radii of curvature for the marking lines in front are further preferably a function of a parameter representative of the type of road, deduced for example images captured by the rear camera. The subject of the invention is also a driving assistance system for a motor vehicle traveling on a running lane, comprising means for determining marking lines at the front of the motor vehicle delimiting said running lane, and means for estimating a distance separating the motor vehicle from said marking lines at the front of the motor vehicle, characterized in that the means for determining the marking lines at the front of the motor vehicle comprise a calculator capable of extracting marking lines at the rear of the motor vehicle from images captured by a camera located at the rear of the motor vehicle, and modeling the marking lines at the front from the marking lines extracted at the rear of the motor vehicle. 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 represents a first driving situation of a motor vehicle equipped with a system according to the invention; FIG. 2 illustrates steps that can be implemented in a driving assistance method according to the invention; FIG. 3 illustrates the principles of the method according to the invention in the context of the first rolling situation of FIG. 1; - Figure 4 illustrates a second rolling situation; - Figures 5 to 7 illustrate the results of different steps of a preferred embodiment of a driving assistance method, particularly suitable for the second rolling situation.

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

FIG. 1 schematically illustrates a motor vehicle 1 traveling on a rolling track 2 in the direction represented by the arrow F. The running track is delimited on either side of the motor vehicle 1 by two marking lines on the ground, here two continuous lines 3, 4. The motor vehicle 1 is equipped with a camera 5 on the back, for example fixed on the rear bumper. The camera 5 is preferably of the same type as that generally used for assistance during a recoil maneuver, with a wide angle of observation, close to 180 degrees, as represented by the hatched portion in FIG.

In a preferred embodiment, the system detects the marking lines from the images obtained by a camera placed at the rear of the vehicle. At time T, a track model is estimated at the rear of the vehicle, which notably comprises the type of marking, the distance of the vehicle to the marking on each side, and a local model of evolution of the marking (radius of curvature , polynomial model, etc). Knowing that the track pattern does not change abruptly over time, the system generates a series of assumptions about the track pattern at the front of the vehicle, based on the estimated model for the rear of the vehicle. At the moment Τ + ΔΤ, part of the track which was at the front of the vehicle begins to be visible in the field of view of the camera placed at the rear of the vehicle. A detection of markings located on this area of the image makes it possible to compare the hypotheses generated in the previous step and to choose the one that fits best. This makes it possible to better anticipate the curvature changes of the track.

In the various running configurations which will be illustrated in FIGS. 3 to 7, for a better understanding of the invention, the following writing conventions will be adopted: - 3f represents the part of the marking line 3 located at the front of the motor vehicle 1; - 3r represents the part of the marking line 3 located at the rear of the motor vehicle 1; 4f represents the part of the marking line 4 situated at the front of the motor vehicle 1; - 4r represents the part of the marking line 4 located at the rear of the motor vehicle 1; 3 represents the part of the marking line 3 situated in the front of the motor vehicle 1, as determined by the system of the invention; 3 represents the part of the marking line 3 situated at the rear end of the motor vehicle 1, as determined by the system of the invention; 4f represents the part of the marking line 4 situated at the front of the motor vehicle 1, as determined by the system of the invention; 4 represents the part of the marking line 4 situated at the rear end of the motor vehicle 1, as determined by the system of the invention.

FIG. 2 illustrates the processing carried out by a driving assistance system according to the present invention, from the images Im captured by the rear camera 5. The system itself (not represented) comprises at least one onboard computer associated with a software module stored in a storage memory.

As previously seen, the assistance to maintain the motor vehicle 1 in its driving lane, or the line crossing risk warning is essentially based on the implementation of a step 100 of determining marking lines 3f, 4f present at the front of the motor vehicle 1, followed by a step 150 for estimating a distance Dest separating the motor vehicle 1 from said marking lines 3f, 4f at the front of the motor vehicle 1.

According to the invention, the step 100 for determining the marking lines at the front of the motor vehicle (1) comprises: a first substep 110 at which the computer will extract, from the images Im supplied by the rear camera 5, the marking lines

as they appear at the rear of the motor vehicle 1. The extraction implements all types of recognition algorithms; a second substep 140 during which the system will model the marking lines

located at the front before from marking lines

back which were extracted at the sub-step.

The tests conducted by the Applicant have shown that the modeling of the front marking lines from the extraction of the rear marking lines gave good results in cases where the motor vehicle 1 is in a straight line. This rolling situation is illustrated in FIG. 3, which shows, on the left-hand side of the figure, the portion of straight line for rolling, and on the right-hand portion the front and rear line portions determined by the system. As shown in FIG. 3, the shape of the rear marking line 3 as extracted by the image processing processing from the rear camera and the shape of the front marking line 3f as modeled by the system are in line with the actual marking lines before 3f and rear 3r. The same goes for the marking line 4.

Conclusive tests have also been obtained when the motor vehicle 1 is inside a curve whose radius of curvature is assumed to be constant. Indeed, in this case, the portions of marking lines at the rear of the vehicle, captured by the rear camera, are curved so that it is possible to determine a radius of curvature p on the marking lines.

extracted at the rear (sub-step 120 of Figure 2), then model the front portions using the same radius of curvature.

There are nevertheless rolling situations, such as that shown in Figure 4, in which the previously described steps may be insufficient. Here, the motor vehicle 1 is about to take a turn on the right. Nevertheless, the rear portion of the road, visible from the rear camera 5 has only straight portions of rear marking lines 3r, 4r. The system can extract, from the images of the camera, rear marking lines

which are true to reality, as shown in the right-hand part of Figure 4, but may make an erroneous estimate, if the modeling is not sufficiently elaborate and is based only on the radius of curvature of the marking lines rear, front marking lines

. This erroneous estimate is also visible on the right side of the figure in which the front marking lines

modeled are straight, and therefore do not conform to the actual front marking lines 3f and 4f. The assistance system may then generate a false alarm or fail to detect an unintentional line crossing.

To solve these particular cases, a preferred embodiment of the system according to the invention comprises an estimation step 130 of a plurality of possible radii of curvature for the marking lines at the front, from the radius of curvature determined in step 120. Thus, instead of modeling a single marking line before

, the system advantageously models several possible marking lines before possible. The result of this step is illustrated on the right side of FIG. 5, where the references

symbolize the bundles of front marking lines modeled for line 3 and line 4, with several possible radii of curvature. In order to limit the number of lines thus modeled, it is advantageous to use additional information such as a parameter representative of the type of road. This parameter can for example be deduced from the images captured by the rear camera 5. Alternatively, this parameter can come from a satellite navigation system fitted to the motor vehicle 1.

As the steps are repeated and the vehicle 1 continues its progression on the taxiway 2, when a new image arrives, a new portion of road that was not visible from the rear camera 5 during the previous iteration becomes visible. As shown in FIG. 6, a new rear marking line

will be able to be extracted from the processing of this new image, and it will be possible to further reduce the number of marking lines before modeled at the previous iteration by selecting the modeled front line that best corresponds to the new line of rear marking extracted

. This modeled and selected line is represented under reference

in Figure 7 (respectively

for the front portion relative to the marking line 3).

Comparing the left and right part of Figure 7, we see that the iterative process allowed to refine the hypotheses on the radii of curvature of the front portions of the marking lines, until selecting a model according to the reality .

The system can then estimate the lateral distance Dest between a modeled front marking line and a point at the front of the vehicle. It is also possible to estimate a lateral distance between a marking line and other specific points of the vehicle (front wheel axis, rear wheel axis, for example). The distances thus estimated, combined with the odometric data of the motor vehicle 1 (for example the speed of the vehicle and its yaw rate measured regularly elsewhere), will allow the system to anticipate an unwanted line crossing, and alert accordingly. the driver and / or control the vehicle to correct its trajectory automatically.

Claims (6)

A driving assisting method for a motor vehicle (1) traveling on a taxiway (2), comprising a step (100) for determining marking lines (3f, 4f) at the front of the vehicle automobile (1) defining said taxiway (2) and a step (150) for estimating a distance separating the motor vehicle (1) from said marking lines (3f, 4f) at the front of the motor vehicle (1 ), characterized in that the step (100) for determining the marking lines (3f, 4f) at the front of the motor vehicle (1) comprises a sub-step (110) for extracting marking lines. at the rear of the motor vehicle from images captured by a camera (5) located at the rear of the motor vehicle (1), and a substep (130, 140) for modeling the marking lines at the front from the marking lines extracted at the rear of the motor vehicle (1). Driving assistance method according to claim 1, characterized in that the sub-step (110) for extracting marking lines at the rear of the motor vehicle (1) is followed by a substep (120) for determining a radius of curvature of the marking lines extracted in the back. Driving assistance method according to claim 2, characterized in that the sub-step (130, 140) for modeling the marking lines at the front comprises estimating (130) a plurality of spokes. possible curvature for the marking lines at the front, from said determined radius of curvature. 4. A driving assistance method according to claim 3, characterized in that said plurality of possible radii of curvature for the marking lines at the front are furthermore function of a parameter representative of the type of road. 5. Driving assistance method according to claim 4, characterized in that said parameter is derived from the images captured by the rear camera (5). 6. A driving assistance system for a motor vehicle (1) traveling on a driving lane (2), comprising means for determining marking lines (3f, 4f) at the front of the motor vehicle (1). ) delimiting said taxiway (2) and means for estimating a distance separating the motor vehicle (1) from said marking lines (3f, 4f) at the front of the motor vehicle (1), characterized in that the means for determining the marking lines (3f, 4f) at the front of the motor vehicle (1) comprise a computer capable of extracting marking lines at the rear of the motor vehicle from images captured by a camera (5) located at the rear of the motor vehicle (1), and to model the marking lines at the front from the marking lines extracted at the rear of the motor vehicle (1).