METHOD FOR CONTROLLING A MOTOR VEHICLE LIGHTING SYSTEM

Abstract

Method for controlling a lighting system with the lighting system including a plurality of light sources, wherein each light source is capable of emitting an elementary light beam with the vertical angular aperture of which is less than 1°. The method includes detecting a target object, determining a relative distance between a given point of the host vehicle sensor system and a detected point of the target object and determining a gradient of the road on which the target object is located, determining a lower angle and an upper angle between a given point of the host vehicle lighting system and a high cut-off point and a low cut-off point, controlling the light sources of the host vehicle lighting system in order to emit a pixelated light beam of the driving beam type in order to generate a dark zone extending substantially between the high and low cut-off points.

Claims

1. A method for controlling a lighting system of a host motor vehicle, the lighting system including a plurality of selectively controllable elementary light sources, each elementary light source being able to emit an elementary light beam the vertical opening angle of which is smaller than 1°, the method comprising: detecting a target object by means of a sensor system of the host vehicle; determining a relative distance between a given point of the sensor system of the host vehicle and a detected point of the target object and determining a slope of the road on which the target object is located; determining, on the basis of the relative distance and of the slope, a lower angle and an upper angle between a given point of the lighting system of the host vehicle and an upper cut-off and a lower cut-off that are together intended to vertically border the target object; controlling the elementary light sources of the lighting system of the host vehicle so as to emit a pixelated high light beam, some of the elementary light sources being controlled, depending on the lower and upper angles, so as to generate, in the light beam, a dark region extending substantially between the upper and lower cut-offs.

2. The method as claimed in claim 1, wherein determining the lower and upper angles includes comparing the slope with a lower threshold and an upper threshold.

3. The method as claimed in claim 1, wherein determining the lower and upper angles includes determining, on the basis of the relative distance and of the slope, a relative height between the given point of the lighting system of the host vehicle and a given point of the target object at which the lower cut-off must be positioned, with the lower and upper angles being determined on the basis of the relative distance, of the slope and of the relative height.

4. The method as claimed in claim 3, wherein determining the lower and upper angles includes predicting a value of the relative height at a future time with respect to the given time.

5. The method as claimed in claim 4, wherein the predicting of the value of the relative height at a future time includes determining a vertical speed of the target object.

6. The method as claimed in claim 3, wherein the value of the lower angle is determined responsive to the relative height and the relative distance.

7. The method as claimed in claim 1, wherein determining the lower and upper angles includes determining the height of the target object, with the value of the upper angle being determined responsive to the value of the lower angle and the determined height.

8. The method as claimed in claim 1, wherein detecting the target object includes classifying the type of the target object among a set of predetermined types of target object.

9. The method as claimed in claim 1, wherein controlling the elementary light sources of the lighting system of the host vehicle includes turning off certain elementary light sources that are each capable of emitting one elementary light beam between the upper and lower cut-offs.

10. A motor vehicle including a sensor system, a lighting system and a controller, with the controller being configured to implement a method, the method comprising: detecting a target object by means of the sensor system; determining a relative between a given point of the sensor system and a detected point of the target object and determining a slope of the road on which the target object is located; determining, on the basis of the relative distance and of the slope, a lower angle and an upper angle between a given point of the lighting system and an upper cut-off and a lower cut-off that are together intended to vertically border the target object; controlling elementary light sources of the lighting system so as to emit a pixelated high light beam, some of the elementary light sources being controlled, depending on the lower and upper angles, so as to generate, in the light beam, a dark region extending substantially between the upper and lower cut-offs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will now be described by way of examples that are merely illustrative and that in no way limit the scope of the invention, and with reference to the accompanying illustrations, in which:

[0038] FIG. 1 shows, schematically and partially, a motor vehicle according to one embodiment of the invention;

[0039] FIG. 2 shows a method according to one embodiment of the invention, implemented by the motor vehicle of FIG. 1;

[0040] FIG. 3 shows a side view of a road scene during the implementation of the method of FIG. 2 by the vehicle of FIG. 1; and

[0041] FIG. 4 shows a front view of a road scene during the implementation of the method of FIG. 2 by the vehicle of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0042] In the following description, elements that are identical in terms of structure or in terms of function and that appear in various figures have been designated with the same reference, unless otherwise indicated.

[0043] FIG. 1 shows a partial view of a host motor vehicle 1 according to one embodiment of the invention. The host motor vehicle 1 comprises a sensor system 2 comprising a device 21, here a laser scanner. In the described example, the laser scanner 21 is located in a lighting system 3 taking the form of a front headlamp of the vehicle 1, and comprises a transceiver arranged to emit light through the outer lens of the headlamp 3 and to receive this light, after it has been reflected. The sensor system 2 further comprises a computer 22 arranged to implement various methods for processing the signals received by the transceiver of the laser scanner 21. The lighting system 3 of the host vehicle 1 comprises a light-emitting module 31. The light-emitting module 31 in particular comprises a pixelated light source 32 associated with a lens 33. In the described example, the pixelated light source 32 is a monolithic pixelated light-emitting diode, each of the light-emitting elements of which forms one elementary light source 32.sub.i,j that is able to be selectively activated and controlled by an integrated controller so as to emit light toward the lens 33, which thus projects onto the road an elementary light beam HD.sub.i,j the light intensity of which is controllable. Each elementary light beam HD.sub.i,j is projected by the lens in a given emission cone defined by a given emission direction and a given opening angle. Thus, in the described example, all of the elementary light beams HD.sub.i,j thus form a pixelated light beam HD that contains 500 pixels in 25 columns and 20 rows, that lies vertically in an angular vertical range from −1° to +5°, and each pixel of which is formed by one of these elementary light beams HD.sub.i,j.

[0044] Each elementary light beam HD.sub.i,j emitted by one of the elementary light sources 32.sub.i,j of the source 32 has a vertical opening angle smaller than 1°. More specifically, the elementary light sources 32.sub.i,j of the source 32 are arranged such that the vertical opening angle of the elementary light beams HD.sub.i,j that they are able to emit decreases with distance from the top of the pixelated light beam. In particular:

[0045] each of the elementary light sources the emission cone of which belongs to the angular vertical range from −1° to +1° is able to emit an elementary light beam the vertical opening angle of which is substantially 0.25°;

[0046] each of the elementary light sources the emission cone of which belongs to the angular vertical range from +1° to +2° is able to emit an elementary light beam the vertical opening angle of which is substantially 0.3°;

[0047] each of the elementary light sources the emission cone of which belongs to the angular vertical range from +2° to +3° is able to emit an elementary light beam the vertical opening angle of which is substantially 0.35′;

[0048] each of the elementary light sources the emission cone of which belongs to the angular vertical range from +3° to +5° is able to emit an elementary light beam the vertical opening angle of which is substantially 0.4°.

[0049] The light-emitting module 31 comprises a controller 34 arranged to control the integrated controller of the pixelated light source 32 so as to selectively control turn-on, turn-off and modification of the light intensity of each of the elementary light beams HD.sub.i,j depending on instructions received from a controller 4 of the host vehicle 1, these instructions in particular being determined on the basis of information delivered by the computer 22 of the sensor system 2 and by a navigation system 11 of the host vehicle 1.

[0050] It will be noted that, in the described example, the laser scanner 21 and the light-emitting module 31 are located substantially at the same level.

[0051] FIG. 2 shows a method for controlling the lighting system 3 of the host vehicle 1, which allows the lighting system 3 to emit a high light beam that will not cause a target object 5 discomfort glare, said method being implemented by the controller 4, and using the sensor system 2 and the navigation system 11. FIG. 3 shows a side view and FIG. 4 shows a front view of the road scene onto which this light beam is projected during the implementation of this method. It will be noted that FIG. 3 and FIG. 4 show only partial views of this light beam.

[0052] In a first step E1, the sensor system 2 detects the presence of a target object 5, in this case a target vehicle 5, on the road. In the described example, the computer 22 implements one or more methods for processing signals received by the transceiver of the laser scanner 21, allowing the target vehicle 5 to be detected. It will possibly for example be a question of methods for measuring the time of flight of the emitted light received, after reflection from the road or from an object on the road, by the transceiver of the laser scanner, and for analyzing this time of flight with a view to detecting the presence of the target vehicle.

[0053] In a second step E2, the computer 22 of the sensor system 2 computes the distance X.sub.HC separating the transceiver of the laser scanner 21 of the host vehicle from the target vehicle 5. Furthermore, the computer 22 classifies the type of the target vehicle among a set of predetermined types of vehicle and determines, on the basis of the selected type of the target vehicle 5, the height H.sub.C of the target vehicle 5 and the height H.sub.HL of the rear lights 51 of the target vehicle 5. Each of these operations may be performed by one or more algorithms for processing signals received by the transceiver of the laser scanner 21 and implemented by the computer 22. All of this information X.sub.HC, H.sub.C, H.sub.HL are transmitted by the computer 22 to the controller 4.

[0054] In a step E2′, the navigation system 11 of the host vehicle transmits information relating to the road over which the host vehicle and the target vehicle 1 are traveling. In particular, the navigation system 11 determines the slope S of the road at the position of the target vehicle 5, on the basis of the known position of the host vehicle 1 and of the distance X.sub.HC that was transmitted to it by the controller 4. The navigation system also determines the distance X.sub.S between the host vehicle 1 and the start of the slope of the road over which the target vehicle 5 is traveling.

[0055] In a step E3, the controller 4 compares the value of the slope S with a lower threshold S.sub.min, for example −13%, and with an upper threshold S.sub.max, for example +13%. If the slope is not comprised between S.sub.min and S.sub.max, the method stops, insofar as it is possible to deduce that the host and target vehicles 1, 5 are traveling on a road the slope of which will not allow or will not require a glare-preventing high-beam function. In the case where the slope S is comprised between S.sub.min and S.sub.max, the method proceeds to the following step.

[0056] In a step E4, the controller 4 determines a relative height Z.sub.C between the lighting system 3 of the host vehicle 1 and the rear lights 51 of the target vehicle 5, by means of the following equation:

[00004]$\begin{array}{cc}{Z}_C=\frac{H_{\mathrm{HL}}}{\sin \left(\frac{\pi }{2}-S\right)}+\tan \left(S\right).Math.\left(X_{\mathrm{HC}}-X_S\right)+H_H& \left[\mathrm{Math}4\right]\end{array}$

[0057] where Z.sub.C is the relative height between the host vehicle 1 and the target vehicle 5, Him is the height of rear lights 51 of the target vehicle 5, S is the slope of the road over which the target vehicle 5 is traveling, X.sub.HC is the distance separating the host vehicle 1 and the target vehicle 5, X.sub.S is the distance separating the host vehicle 1 from the start of the slope of the road on which the target vehicle 5 is located and H.sub.H is the height of the sensor system 2 of the host vehicle 1.

[0058] The relative height Z.sub.C determined by the controller 4 is relative to the position of the target vehicle 5 at the time t of its detection by the computer 22. However, the various methods implemented by the computer 22 of the sensor system 2 and the steps of the method according to the invention, which will be described below, and which allow a glare-preventing high beam to be generated by the lighting system 3, require a given execution time ΔT, after which the beam is actually emitted. During this time ΔT, the target vehicle 5 may have moved such that the value of the relative height Z.sub.C no longer corresponds to the actual position of the target vehicle 5 when the beam is emitted.

[0059] In order to compensate for this latency, in a step E5, the controller 4 predicts a value of a relative height Z.sub.C′ between the host vehicle 1 and the rear lights 51 of the target vehicle 5 at a future time t+Δt with respect to the time t of detection by the computer 22 of the target vehicle 5 in step E1. To these ends, the controller 4 determines a vertical speed Ż of the target vehicle 5, via differentiation of the various values of the vertical height Z.sub.C determined beforehand in steps E4. The predicted value Z.sub.C′ may thus be obtained by means of the following equation:

Z′.sub.C=Z.sub.C+Ż.Math.Δt  [Math 5]

[0060] where Z.sub.C is the value of the relative height at the time t, i.e. the value determined in step E4, Z.sub.C′ is the predicted value of the relative height at the future time t+Δt, Ż is the vertical speed of the target vehicle 5 and Δt is the latency time of the method according to the invention.

[0061] In a step E6, the controller 4 determines a lower angle V.sub.inf between the light-emitting module 31 and the rear lights 51 of the target vehicle 5, by means of the following equation:

[00005]$\begin{array}{cc}{V}_{\inf }={\tan }^{-1}\left(\frac{Z_C^{\prime }}{X_{\mathrm{HC}}}\right)& \left[\mathrm{Math}6\right]\end{array}$

[0062] where V.sub.inf is the lower angle, Z′.sub.C is the relative height predicted in step E5 and X.sub.HC is the distance separating the host vehicle 1 and the target vehicle, which distance is determined in step E2.

[0063] Moreover, still in step E6, the controller 4 determines an upper angle V.sub.sup on the basis of the value of the lower angle V.sub.inf obtained beforehand and of the height of the target vehicle H.sub.C determined in step E2, for example using the following equation:

[00006]$\begin{array}{cc}{V}_{\sup }={\tan }^{-1}\left(\frac{H_C-H_{\mathrm{HL}})}{X_{\mathrm{HC}}}\right)+V_{\inf }& \left[\mathrm{Math}7\right]\end{array}$

[0064] where V.sub.sup is the upper angle, H.sub.HL is the height of the rear lights 51 of the target vehicle 5, X.sub.HC is the distance separating the host vehicle 1 and the target vehicle 5, H.sub.c is the height of the target vehicle 5 and V.sub.inf is the value of the lower angle.

[0065] At the end of step E6, the controller 4 transmits the pair of lower and upper angles Via, V.sub.sup to the controller 34 of the light-emitting module 31. Furthermore, in steps that are not described, the controller 4 determines a pair of right and left lateral angles V.sub.LD, V.sub.LG, respectively, on the basis of the positions of the rear lights 51 of the target vehicle 5 and also transmits this pair of angles to the controller 34.

[0066] In a step E7, the controller 34 selects those elementary light sources 32.sub.i,j of the light source 32 which are able to emit elementary light beams HD.sub.i,j whose emission cones are vertically at least partially between the lower V.sub.inf and upper V.sub.sup angles and horizontally at least partially between the right V.sub.LD and left V.sub.LG lateral angles. The controller 34 thus controls the turning-off of these selected elementary light sources 32.sub.i,j while controlling the turning-on of the other elementary light sources. The light-emitting module 1 thus emits a pixelated high light beam HD in which is formed a dark region Z.sub.C that is centered on the target vehicle 5 and defined vertically by lower and upper cut-offs that each make a vertical angle to the light-emitting module 1, and the respective values of which are substantially V.sub.inf and V.sub.sup; and that is defined horizontally by right and left lateral cut-offs that each make a horizontal angle to the light-emitting module 1, and the respective values of which are substantially V.sub.LD and V.sub.LG. It will be noted that the term “substantially” must here be interpreted with regard to the vertical and horizontal resolutions of the pixelated light beam HD.

[0067] The above description clearly explains how the invention allows the objectives that were set therefor to be achieved, in particular by providing a method for controlling a lighting system of a host vehicle that controls turn-on or turn-off of the elementary light sources of the lighting system so as to generate, in a pixelated light beam, a dark region bounded by an upper cut-off and a lower cut-off the positions of which are determined on the basis of information output from a sensor system of the host vehicle, and in particular information relating to the vertical position, on the road, of a target object to not be subject to discomfort glare.

[0068] In any event, the invention should not be regarded as being limited to the embodiments specifically described in this document, and extends, in particular, to any equivalent means and to any technically operative combination of these means. In particular, it is possible to envisage types of light-emitting module other than the one described, and in particular a light-emitting module comprising an association of a light source and of a digital micromirror device. It will also be possible to envisage other methods for determining the various values used in the equations that allow the values of the lower and upper angles to be determined, or even equations other than those which have been described, and in particular equations integrating margins that allow the position of the upper and lower cut-offs of the dark region in the pixelated light beam to be moved vertically.