Method for displaying the trajectory of a moving motor vehicle

Abstract

The invention relates to a method for displaying, in a moving motor vehicle, the future trajectory of the motor vehicle. The vehicle includes a digital recording device (10) providing digital signals of the scene unfolding in front of it.The process comprises the following steps: the digital signals are processed to generate two lateral boundary lines (22, 24) of the future trajectory of the vehicle, and two polynomial functions corresponding to these two boundary lines are determined; the radii of curvature R of the two lateral boundary lines (22, 24) are evaluated from these two polynomial functions; damping factors are defined as functions of the radii of curvature R of the two lateral boundary lines (22, 24); and these damping factors are applied to the two polynomial functions to display two damped lateral boundary lines of the future trajectory of the vehicle. Figure to be published with the abstract: Fig. 1.

Description

Title of the invention: Method for displaying the trajectory of a moving motor vehicle

[0001] The present invention relates to a method for displaying the future trajectory of a moving motor vehicle.

[0002] The present invention also relates to a motor vehicle including the means for implementing said display method.

[0003] In the context of the implementation of autonomous vehicles in particular, it is envisaged to be able to represent as faithfully as possible, on a display device internal to the vehicle, the environment perceived by the driver.

[0004] It is known to equip motor vehicles with a digital recording device adapted to provide digital signals representative of the scene taking place in front of the vehicle when the latter is in motion.

[0005] In other words, a digital camera is installed at the front of the motor vehicle and the camera is pointed precisely forward. It is then possible to display these digital signals via an on-board computer, on a screen installed in the vehicle.

[0006] It is also possible to process these digital signals to be able to reconstruct, seen from above, an image of the motor vehicle in motion and its environment as well as its future trajectory. This image can of course be displayed on the vehicle's screen.

[0007] It is also possible to transfer onto the image the representation of other vehicles located in the environment of the EGO vehicle. It can also include pictograms making it possible to highlight the vehicle in front, for example, or even to highlight the trajectory, when the vehicle is poorly centered.

[0008] However, such a reconstruction of the future trajectory of the vehicle is relatively faithful to reality in a close environment, but the further forward one projects, the less faithful it is. When the motor vehicle moves on a straight line, few distortions appear. On the other hand, when the vehicle follows winding paths, the representation of the future trajectory of the environment perceived by the driver is fluctuating and is less faithful.

[0009] Also, a problem which arises and which the present invention aims to solve is to provide a method for displaying the future trajectory of the motor vehicle which is more faithful to reality.

[0010] In order to solve this problem, and according to a first object, a method is proposed for displaying, in a moving motor vehicle, the trajectory future of said motor vehicle, said motor vehicle comprising a digital recording device adapted to provide digital signals representative of the scene taking place in front of said motor vehicle.Said method comprises the following steps: processing said digital signals to develop at least two lateral boundary lines of the future trajectory of said moving motor vehicle and determining two polynomial functions corresponding respectively to said at least two boundary lines; evaluating the radii of curvature of said at least two lateral boundary lines from said two polynomial functions; defining damping factors respectively as a function of said radii of curvature of said at least two lateral boundary lines; and applying said damping factors respectively to said two polynomial functions to be able to display two damped lateral boundary lines of the future trajectory of said motor vehicle.

[0011] Thus, a characteristic of the invention lies in the implementation of damping factors on the two lateral delimitation lines of the trajectory representative of the two corresponding polynomial functions as a function of the radius of curvature of these two lines. These damping factors are intended in particular to attenuate the curvature of the two lateral delimitation lines, in particular at the back of the field when the trajectory of the vehicle is very sinuous. Indeed, the radii of curvature are very fluctuating and without correction in accordance with the invention, the lateral delimitation lines oscillate violently and offer an unpleasant visual impression for the driver.

[0012] For example, the two lateral delimitation lines of the trajectory correspond, on the right of the trajectory, to the white broken line delimiting the roadway of the verge, and on the left, to the central white line of the roadway.

[0013] As will be explained in the remainder of the description, the radius of curvature is easily calculable from the polynomial functions corresponding to the two lateral boundary lines. Indeed, it is obtained by calculating the first derivative and the second derivative of the polynomial functions.

[0014] Furthermore, said at least two lateral delimiting lines are substantially parallel to each other, and consequently, their radii of curvature are locally substantially identical. Therefore, the damping factors applied to the two polynomial functions are advantageously identical.

[0015] According to a particularly advantageous embodiment of the invention, said digital signals are processed to develop at least two other lateral delimitation lines respectively opposite said trajectory with respect to said at least two lateral delimitation lines, and two other polynomial functions are determined corresponding respectively to said two other delimitation lines. lateral.

[0016] In this way, the vehicle's trajectory is even better delimited. It allows any uncertainty about the future trajectory to be removed.

[0017] Also, one of the other lateral boundary lines corresponds, on the right, to the verge itself, while the other lateral boundary line corresponds, on the left, to the other white broken line, delimiting the roadway and the opposite verge.

[0018] Advantageously, the method according to the invention further comprises the following steps: the radii of curvature of said at least two other lateral delimitation lines are evaluated from said two other polynomial functions; other damping factors are calculated, respectively proportional to said radii of curvature of said at least two other lateral delimitation lines; and, said other damping factors are applied respectively to said two other polynomial functions in order to be able to display two other damped lateral delimitation lines of the future trajectory of said motor vehicle.

[0019] Thus, the procedure is the same as for the said at least two lateral delimitation lines.

[0020] Advantageously, the damping factors applied to the other two polynomial functions are also identical.

[0021] Also, according to a particularly advantageous embodiment of the invention, said damping factors are applied respectively to the arguments of greatest power of said at least two polynomial functions. In this way, the damping factors are applied to the member of the polynomial functions which have the greatest repercussion in the background of the field.

[0022] Preferably, other damping factors are also applied respectively to all the coefficients of said at least two polynomial functions. Advantageously, a single other damping factor is applied to all the coefficients of said at least two polynomial functions, before applying the damping factors to the arguments of greater power. On the other hand, said single other damping factor is lower.

[0023] According to a particularly advantageous embodiment of the invention, said polynomial functions are of the third degree. Therefore, they are defined respectively by four coefficients corresponding respectively to the position, when the argument is zero, to the angle of curvature for the argument of the first degree, to the curvature for the argument of the second degree and to the derivative of the curvature for the argument of the third degree.

[0024] Also, preferably, said damping factors are defined proportional to said radii of curvature.

[0025] According to a particular embodiment, a plurality of successive intervals of increasing values ​​of said radius of curvature are defined, and damping factors of a progressive series of a plurality of damping factors between zero and one are respectively associated with the successive intervals. In this way, each of the intervals corresponds to a predefined damping factor. And the damping factor corresponding to the interval to which the calculated radius belongs is applied.

[0026] Thus, the smaller the radius of curvature, the greater the curvature and therefore a lower damping factor will be applied. Conversely, the larger the radius of curvature, the smaller the curvature and a higher damping factor, but less than 1, will be applied.

[0027] According to a preferred embodiment of the invention, said steps are implemented at a frequency of between 1 Hz and 20 Hz. For example, the steps are implemented at a frequency of between 5 Hz and 15 Hz and preferably ten hertz. In this way, the algorithm for implementing the method according to the invention operates every 10 ms. In other words, the attenuated lateral delimiting lines are recalculated 10 times per second. This makes it possible to considerably dampen the fluctuations of the lateral delimiting lines of the vehicle's trajectory.

[0028] According to another object, and with a view to solving the problem posed, a motor vehicle is proposed comprising: a digital recording device adapted to provide digital signals representative of the scene taking place in front of said motor vehicle; an on-board computer connected to said digital recording device to process said digital signals; a display device connected to said on-board computer to be able to display, from said processed digital signals, the future trajectory of said motor vehicle when it is in motion.And said on-board computer further comprises: first calculation means for developing at least two lateral delimitation lines of the future trajectory of said moving motor vehicle and for determining two polynomial functions corresponding respectively to said at least two delimitation lines; second calculation means for evaluating the radii of curvature of said at least two lateral delimitation lines from said two polynomial functions; third calculation means for defining damping factors respectively as a function of said radii of curvature of said at least two lateral delimitation lines; and, fourth calculation means for applying said damping factors respectively to said two polynomial functions and for being able to display on said display device, two damped lateral delimitation lines of the future trajectory of said motor vehicle.

[0029] Furthermore, the on-board computer is also adapted to process said signals. merics and to develop the other two lateral boundary lines and to determine two other corresponding polynomial functions.

[0030] Also, the on-board computer makes it possible to evaluate the radii of curvature of said at least two other lateral delimiting lines from said two other polynomial functions; to calculate other damping factors respectively proportional to said radii of curvature; and, to apply said other damping factors respectively to said two other polynomial functions.

[0031] In other words, the on-board computer of the motor vehicle allows the implementation of the method according to the invention defined above. Also, the same advantages result from it.

[0032] Other features and advantages of the invention will emerge from reading the description given below of particular embodiments of the invention, given for informational but non-limiting purposes, with reference to the appended drawings in which:

[0033] [Fig-1] is a schematic view of the representation of a scene and its retrans description on a screen in the absence of processing;

[0034] [Fig.2] is a schematic view of the representation of the scene illustrated in the [Fig.l] and its transcription on the screen after processing;

[0035] [Fig.3] is a schematic view of the representation of another scene and its re transcription on a screen in the absence of processing;

[0036] [Fig.4] is a schematic view of the representation of said other scene illustrated on [Fig.3] and its transcription on the screen after processing;

[0037] [Fig.5] is a block diagram of an installation allowing the implementation of the process according to the invention; and,

[0038] [Fig.6] a processing flowchart representing the sequence of steps of the method according to the invention.

[0039] Reference will first be made to [Fig. 5] showing a digital camera 10 installed at the front of a motor vehicle (not shown). The digital camera 10 is connected to an on-board computer 12. And the motor vehicle is equipped with a display screen 14 connected to the on-board computer 12. The digital camera 10, or digital recording device, is oriented in such a way that it can provide the on-board computer 12 with digital signals representative of the scene taking place at the front of said motor vehicle. In other words, the digital signals provide an image of what the driver installed in his vehicle can see.

[0040] Such an installation is of interest when the vehicle is in motion. The on-board computer 12 includes calculation means which will be detailed in the remainder of the description.

[0041] [Fig.l] shows, on the one hand, a scene 16 provided by the digital camera 10, and on the other hand a graphic representation in a reference frame (X, Y) expressed in meters, of boundary lines of the future trajectory of the motor vehicle 18, which is represented on the abscissa line.

[0042] These lateral delimitation lines are produced by first calculation means 20 using the digital signals supplied by the digital camera 10. The first calculation means 20 then determine third-degree polynomial functions in the form: Y = C3 X3 + C2 X2 + Ci X + Co, for each of the lateral delimitation lines, and proceed to display them on the screen 14.

[0043] Thus, among these lateral delimitation lines, two first proximal lines are observed, on each side of the EGO vehicle 18, a first straight line 22 and a first left line 24. Two second distal lines are also observed, a second straight line 26 and a second left line 28.

[0044] The first straight line 22 corresponds to the broken white line 30 appearing on the scene 16 and delimiting the roadway 32 from the verge 34. And the first left line 24 corresponds to the central broken white line 36 of the roadway 32.

[0045] The second straight line 26 corresponds to the verge itself, while the second left line 28 corresponds to the other white broken line 38, delimiting the roadway 32 and the opposite verge 40.

[0046] The first calculation means 20 develop these lines 22, 24, 26, 28 over a background distance corresponding to a longitudinal distance of 80 m, as illustrated in the reference (X, Y).

[0047] As can be observed by comparing scene 16 and lines 22, 24, 26, 28 in the (X, Y) frame of reference, the curvature of lines 22, 24, 26, 28 intensifies and becomes excessive compared to the actual trajectory that the motor vehicle 18 will have to take.

[0048] Thus, the object of the invention is to correct the curvature of the lines 22, 24, 26, 28 delimiting the future trajectory of the vehicle 18 in order to make them more faithful to the actual trajectory.

[0049] To do this, the display method according to the invention is implemented in accordance with the flowchart in [Fig.6].

[0050] Thus, the trajectory delimitation lines 22, 24, 26, 28 will be smoothed by modifying respectively the coefficients C3, C2, Ci, Co of the corresponding polynomial functions throughout the evolution of the motor vehicle in order to improve the visual comfort of observation of the lines. This avoids displaying minor cuts and excessively abrupt changes of direction are absorbed.

[0051] Also, the damping algorithm is divided into three successive steps. Thus, we first evaluate the radius of curvature of lines 22, 24, 26, 28. Then we define a damping factor as a function of the radii of curvature. And finally, we apply the damping factor to the coefficient of polynomial functions, having the most impact on the curve.

[0052] In the example presented here, the damping factor will then be applied only to the coefficient C3 of the argument to the power of three, which has the greatest impact on the lines at the bottom of the field.

[0053] Furthermore, the radius of curvature R is easily obtained by calculating the first derivative and the second derivative of the polynomial functions. R is in fact equal to: ( 1 + y'2)3 / 2 / y”, and y' = 3C3 X2 + 2C2 X + Ci, while y” = 6C3 X + 2C2.

[0054] Therefore, a first step 42 therefore consisted of processing the digital signals provided by the digital camera 10 using the first calculation means 20 and of developing the four lateral delimitation lines 22, 24, 26, 28 and of determining four corresponding polynomial functions.

[0055] Also, in a second step 44, using second calculation means 45, the radii of curvature R of each of the lines 22, 24, 26, 28 are then calculated. More precisely, for each of them, the radius of curvature is calculated over the length ranging from 1 m to 80 m, in increments of 1 m. And out of the 80 radii of curvature calculated, the value of the smallest radius is chosen, and therefore of the local curvature of the largest line.

[0056] Then, in a third step 46, and using third calculation means 47, the corresponding damping factors are defined.

[0057] According to an exemplary implementation, five radius of curvature intervals are defined: [0; 70[, [70; 100[, [100; 150[, [150; 200[ and [200; + oo[, and five corresponding damping factors respectively: 0.3; 0.4; 0.6; 0.8 and 1. In other words, when the calculated and chosen radius of curvature belongs to the interval [0; 70[, the value of the determined damping factor is: 0.3. When the radius of curvature is greater than 200 m, the damping factor is equal to unity.

[0058] It will be observed that the four lateral delimiting lines 22, 24, 26, 28 are substantially parallel to each other. Consequently, the locally calculated radii of curvature are substantially identical and therefore belong to the same interval. In this way, the same damping factor is determined for the four lateral delimiting lines 22, 24, 26, 28.

[0059] In this case, the value of the smallest radius of curvature, calculated in the second step 44 belongs to the second interval [70; 100[, and consequently, the corresponding damping factor is: 0.4.

[0060] And in a fourth step 48, using fourth calculation means 50, the determined damping factor is applied to the single coefficient C3 of the four corresponding polynomial functions.

[0061] After the fourth step 48, the fourth calculation means 50 then cause the display of four damped lateral boundary lines 22', 24', 26', 28' as illustrated in [Fig.2]. It will then be observed that the first two proximal curves 22, 24, illustrated in [Fig.l] and delimiting the future course of the motor vehicle 18, at the abscissa - 60 m, are at the ordinate substantially greater than 70 m, while the first two damped proximal curves 22', 24', at the abscissa - 60 m, are at an ordinate close to 80 m.

[0062] It is thus understood that without correction, the representation of the lateral delimitation lines 22, 24, 26, 28 tend to have significantly increased curvatures.

[0063] Also, the algorithm of the flowchart above is operated at a frequency between 1 Hz and 20 Hz. Preferably, the algorithm is operated at a frequency of 10 Hz, i.e. every 10 ms. Consequently, if the motor vehicle is at a speed of 72 km / h, the four lateral delimiting lines 22, 24, 26, 28 are re-evaluated every two meters traveled by the vehicle.

[0064] Furthermore, preferably, prior to applying the damping factor to the coefficient C3 alone, and this at each 10 ms cycle, a first damping is applied to all the coefficients coefficient C3, C2, Ci, Co, of the four polynomial functions, in order to be able to ensure a “harmonious” movement and continuity of the line layout.

[0065] Reference will now be made to [Fig.3] and [Fig.4] illustrating another example of another scene and its damped reproduction, where the original curvature of the lateral boundary lines is less.

[0066] [Fig. 3] shows a scene 116 provided by the digital camera 10, and a graphic representation in a reference frame (X, Y), of a first straight line 122 and a first left line 124 on each side of the EGO vehicle 118 and of a second straight line 126 and a second left line 128.

[0067] The first straight line 122 corresponds to the broken white line 130 appearing on the scene 116 and delimiting the roadway 132 from the verge 134. And the first left line 124 corresponds to the central broken white line 136 of the roadway 132.

[0068] The second straight line 126 corresponds to the verge itself 134, while the second left line 128 corresponds to the other white broken line 138, delimiting the roadway 132 and the opposite verge 140.

[0069] The first calculation means 20 illustrated in [Fig.5] develop these lines 122, 124, 126, 128 in the same way over a background distance corresponding to a longitudinal distance of 80 m, as illustrated in the reference frame (X, Y).

[0070] To correct the curvature of the lines 122, 124, 126, 128 delimiting the future trajectory of the vehicle 118, the display method is also implemented in accordance with the flowchart of [Fig.6].

[0071] In the same way, the trajectory delimitation lines 122, 124, 126, 128 will be smoothed by modifying respectively the coefficients C3, C2, Cb Co of the corresponding polynomial functions, throughout the evolution of the motor vehicle.

[0072] In this case, the value of the smallest radius of curvature, calculated in the second step 44 of the flowchart belongs to the fourth interval [150; 200[ defined above, and consequently, the corresponding damping factor is: 0.8.

[0073] And in the fourth step 48, thanks to the fourth calculation means 50, the damping factor, “0.8” is applied to the sole coefficient C3 of the four corresponding polynomial functions.

[0074] After the fourth step 48, the fourth calculation means 50 then cause the display of the four damped lateral delimiting lines 122', 124', 126', and 128' as illustrated in [Fig.4].

[0075] The invention also relates to a motor vehicle equipped with a camera, an on-board computer and a display screen making it possible to implement the display method according to the invention.

Claims

Claims

1. Method for displaying, in a moving motor vehicle, the future trajectory of said motor vehicle, said motor vehicle comprising a digital recording device (10) adapted to provide digital signals representative of the scene taking place in front of said motor vehicle, characterized in that it comprises the following steps: - said digital signals are processed to develop at least two lateral delimitation lines (22, 24; 122, 124) of the future trajectory of said moving motor vehicle and two polynomial functions corresponding respectively to said at least two delimitation lines are determined; - the radii of curvature R of said at least two lateral delimitation lines (22, 24; 122, 124) are evaluated from said two polynomial functions;- damping factors are defined respectively as a function of said radii of curvature R of said at least two lateral delimitation lines (22, 24; 122, 124); and, - said damping factors are applied respectively to said two polynomial functions in order to be able to display two damped lateral delimitation lines (22', 24'; 122', 124') of the future trajectory of said motor vehicle.;

2. Display method according to claim 1, characterized in that said digital signals are processed to develop at least two other lateral delimitation lines (26, 28; 126, 128) respectively opposite to said trajectory with respect to said at least two lateral delimitation lines (22, 24; 122, 124), and in that two other polynomial functions are determined corresponding respectively to said two other lateral delimitation lines.

3. Display method according to claim 2, characterized in that it further comprises the following steps: - the radii of curvature of said at least two other lateral delimiting lines (26, 28; 126, 128) are evaluated from said two other polynomial functions; - other damping factors respectively proportional to said radii of curvature of said at least two other lateral delimiting lines are calculated; and, - said other damping factors are applied respectively to said two other polynomial functions in order to be able to display two other damped lateral delimitation lines (26', 28'; 126', 128') of the future trajectory of said motor vehicle.

4. Display method according to any one of claims 1 to 3, characterized in that said damping factors are applied respectively to the arguments of greatest power of said at least two polynomial functions.

5. Display method according to any one of claims 1 to 4, characterized in that other damping factors are also applied respectively to all the coefficients of said at least two polynomial functions.

6. Display method according to any one of claims 1 to 5, characterized in that said polynomial functions are of the third degree.

7. Display method according to any one of claims 1 to 6, characterized in that said damping factors are defined proportional to said radii of curvature.

8. Display method according to any one of claims 1 to 7, characterized in that a plurality of successive intervals of increasing values ​​of said radius of curvature are defined, and damping factors of a progressive series of a plurality of damping factors between zero and one are respectively associated with the successive intervals.

9. Display method according to any one of claims 1 to 8, characterized in that said steps are implemented at a frequency of between 1 Hz and 20 Hz.

10. Motor vehicle comprising: - a digital recording device (10) adapted to provide digital signals representative of the scene taking place in front of said motor vehicle; - an on-board computer (12) connected to said digital recording device (10) to process said digital signals; - a display device (14) connected to said on-board computer (12) to be able to display, from said processed digital signals, the future trajectory of said motor vehicle when it is in motion; characterized in that said on-board computer (12) further comprises: - first calculation means (20) for developing at least two lines lateral delimitation lines (22, 24; 122, 124) of the future trajectory of said moving motor vehicle and for determining two polynomial functions corresponding respectively to said at least two delimitation lines; - second calculation means (45) for evaluating the radii of curvature R of said at least two lateral delimiting lines (22, 24; 122, 124) from said two polynomial functions; - third calculation means (47) for defining damping factors respectively as a function of said radii of curvature of said at least two lateral delimiting lines (22, 24; 122, 124); and, - fourth calculation means (50) for applying said damping factors respectively to said two polynomial functions and for being able to display on said display device, two damped lateral delimitation lines (22', 24'; 122', 124') of the future trajectory of said motor vehicle.

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