FR2988052A1 - Method for adapting e.g. brightness of illuminating or signaling light source of car, involves determining brightness value of light source, and adjusting brightness value in order to reach value of determined characteristic brightness - Google Patents

Abstract

The method involves determining an illumination representative value (E1) to which a vehicle powered by part of its environment is subjected. A brightness value of a light source is determined (E2) based on the determined illumination representative value, where the brightness value is a characteristic of a contrast higher than a predetermined threshold of contrast between the light source and the environment of the vehicle. The brightness value of the light source is adjusted (E3) in order to reach a value of determined characteristic brightness. An independent claim is also included for a system for adapting a photometric parameter of an illuminating or signaling light source of a car.

Description

The present invention relates to a method of adapting one or more photometric parameters, such as luminance or luminance, to a photometric parameter of a light source of a motor vehicle and corresponding matching system. light intensity, of a light source of a motor vehicle such as a lighting device or a signaling device. The invention also relates to a corresponding adaptation system for the implementation of such a method. Adaptive headlights are presently known, that is to say having functionalities to adapt to the conditions of the road. With such adaptive headlights, the beams can be directed by moving each headlight to the left, right, up or down depending in particular on the angle of the steering wheel, the speed and the movement of the vehicle. The ground thus remains well lit, whether the vehicle has a strong deceleration, or acceleration, and also ensures in turns that the beam illuminates the roadway and not the side of the road. There may also be a switch to control the ignition or stopping of high beam under certain conditions, or the daytime running lights of the vehicle or "Daytime Running Lights" in English. These features of the adaptive headlights are generally controlled using a camera, or depending on the position of the driving wheel or the analysis of the speed of the vehicle or any sensor on the vehicle. However, this is information that does not represent the actual visibility of the road by the driver. Thus, in case of passage for example under a bridge, the lights are running despite good visibility of the road. This has an impact on the duration of the lamps. Moreover, the lighting value of the vehicle daytime lights, for example, is set for the sunny days in order to be seen by the other road users. However, on a cloudy day these daytime lights dazzle other users. In addition, the power consumption is not adapted to the real need to be seen and this affects in particular the fuel consumption, the CO2 emission and the mileage. The control of the ignition or stopping of the lights of the vehicle, therefore does not adapt to the real need of the driver according to the driving conditions encountered. Moreover, in foggy weather visibility of the scene is reduced, which can cause accidents. To improve visibility in foggy weather, current vehicles are compulsorily equipped with fog lamps at the rear and more fog lamps at the front (not mandatory). The lighting and stopping of these fog lamps are traditionally controlled manually by the driver through a switch disposed on the dashboard. However, the use of fog lights is not always well done by motor vehicle drivers. This can pose security problems. 15 If the driver forgets to activate his fog lights, there is a significant danger situation. And on the contrary, a vehicle whose fog lights are on when there is no fog, can be dangerous for vehicles that precede or follow it. Indeed, the driver behind can be dazzled and do not quickly distinguish an ignition of the brake indicator lights 20 of the vehicle in front, thereby causing a risk of collision. In order to remedy the problems mentioned above, several solutions have been proposed to provide devices for detecting the presence of fog to automatically control the lighting of the lights. This is an all-or-nothing operation that sends a control signal to the fog lamps, depending on whether there is fog or not. However, this operation does not quantify the fog density and therefore provides no information on the actual visibility of the driver in the presence of fog. To remedy this, solutions are known that make it possible to determine the driver's visibility distance in the presence of fog so as to influence the intensity of the lights or the speed of the vehicle according to the visibility of the driver. However, such methods may involve considerable processing work.

The invention therefore aims to overcome at least one of the disadvantages of the prior art by proposing a photometric parameter adaptation method of one or more light sources of the vehicle, simple implementation, to adapt the lighting of the vehicle to the real conditions of visibility by avoiding dazzling the other users and by limiting the electrical consumption. To this end, the subject of the invention is a method for adapting at least one photometric parameter of at least one lighting or signaling light source of a motor vehicle, characterized in that it comprises the steps following: a value representative of the illumination to which said vehicle generated by at least a part of the environment of said vehicle is determined, from said value representative of the determined illumination, a value of the luminance of said vehicle is determined; a light source, said luminance value being characteristic of a contrast greater than a predetermined threshold of contrast between said light source and the environment of said vehicle, and the value of the luminance of said light source is adjusted so as to reach said value of characteristic luminance determined. Said method may further comprise one or more of the following characteristics, taken separately or in combination: a value of the luminance of at least part of the environment of said vehicle is determined, and from said determined value of luminance from less part of the environment of said vehicle, a value of the luminance of said light source is determined, the predetermined threshold of contrast is of the order of 5%. ; said characteristic value of the luminance of said light source is calculated from said value representative of the determined illumination, and from said predetermined threshold of contrast; said method comprises: a preliminary step in which a correspondence graph is established between values representative of the illumination to which said vehicle is subjected and luminance values of said light source that are characteristic of a contrast greater than said predetermined contrast threshold, and a reading step of said correspondence graph so as to determine the characteristic value of the luminance of said light source according to said determined value representative of the illumination to which said vehicle is subjected; said method may comprise the following steps: - at least one speed information is recorded, and - the adjustment of at least one photometric parameter of said light source is controlled according to said detected speed information. ; said method may comprise the following steps: the required visibility distance is calculated according to said at least one speed information, and the adjustment of at least one photometric parameter of said light source is controlled according to said distance required required visibility; there is speed limit information; real speed information of said vehicle is recorded; said method comprises the following steps: - comparing said speed limit and said actual speed, and - if the actual speed is greater than said speed limit, calculating the required visibility distance from said actual speed.

In the case where the speed of the vehicles arriving opposite is known, this speed is also taken into account in the calculation of the required visibility distance. According to an alternative embodiment, the method may comprise the following steps: the distance of visibility is calculated from said calculated visibility distance, the atmospheric extinction coefficient is determined, and the luminance is adjusted; of said light source according to said determined extinction coefficient The luminance of said light source is for example adapted to obtain a visibility distance required to be seen, at least greater than twice the stopping distance of the vehicle. Said method can comprise the following steps: - the presence of at least one parameter which disturbs the visibility is detected, - the visibility distance is evaluated, - the adjustment of at least one photometric parameter of said light source is controlled according to of said visibility distance. According to an alternative embodiment, the light intensity of said light source is increased according to a predefined correspondence table between the visibility distance and the light intensity. The method may include a step in which a transition between day and night is detected. The method may include a step in which the presence of fog is detected. According to one embodiment, it controls the automatic ignition of at least one light source called anti-fog. The method may include a step of inhibiting the high beam lighting. According to an alternative embodiment, said method comprises a preliminary step 25 in which matches are defined between at least one visibility threshold and a fog density. According to an exemplary implementation of the method, the adjustment of at least one photometric parameter continuously is controlled by pulse width modulation. According to another example of implementation of the method, the adjustment of at least one step photometric parameter is controlled. The invention also relates to a system for adapting at least one photometric parameter of a lighting or signaling light source of a motor vehicle, for the implementation of such a method, characterized in that said system comprises: at least one processing means for determining a value representative of the illumination to which said vehicle generated by at least part of the environment of the vehicle or a value of the illumination at the level of the vehicle generated by at least part of the environment, at least one processing means for determining a value of the luminance of said light source characteristic of a contrast greater than a predetermined threshold of contrast between said light source and the environment of said vehicle, to from said value representative of the determined illumination, and a control device of said light source connected to at least one trapping means. itement, comprising a transmitter of a control signal for adjusting the value of the luminance of said light source so as to reach said determined characteristic luminance value. The system may further comprise one or more of the following features, taken separately or in combination: said system comprises at least one processing means for reading speed information, and said control signal is configured to adapt to at least one photometric parameter of said light source as a function of said speed information; Said system comprises: at least one means for detecting the presence of a parameter disturbing the visibility of the environment of said vehicle, and at least one processing means for determining the visibility distance when a parameter disturbing the visibility has been detected, and said control signal is configured to control the ignition and / or adaptation of at least one photometric parameter of said light source as a function of the visibility distance; Said parameter disturbing the visibility of the environment of said vehicle may comprise at least one parameter of the group comprising: night, fog, snow, rain, smoke; said system is connected to a driver assistance system and / or a navigation system. Other features and advantages of the invention will emerge from the following description, given by way of example, without limitation, with reference to the accompanying drawings, in which: FIG. 1 schematically represents an adaptation system of FIG. At least one photometric parameter of at least one light source of a motor vehicle, FIG. 2 schematically represents the various steps of a method for adapting the luminance of the daytime running lights of the vehicle according to the ambient luminance of the vehicle. vehicle environment or level of illumination received at the vehicle, Figure 3 schematically illustrates the correspondence between ambient luminance levels or levels of illumination level at the vehicle and the luminance of the daylighting of the vehicle. FIG. 4 schematically represents the various steps of a method for adapting the luminance of the daytime lights by according to the required visibility distance, FIG. 5 is a graph showing schematically and simplified the steps of a method for adapting the luminance of the daytime running lights as a function of both the ambient luminance and / or the level of illumination. illumination on the vehicle, and the required viewing distance, FIG. 6 schematically illustrates correspondence between speed bearings and the luminance of the vehicle daytime lights, FIG. 7 is a graph showing diagrammatically and simplified the steps of a method for adjusting the light intensity of the fog lamps and the signaling lights in the event of fog, and FIG. 8 schematically and simplifies the steps of a method for adapting the luminance of the headlights to night mode. In these figures the substantially identical elements bear the same reference numbers. The invention relates to the possibility of modulating or adjusting at least one photometric parameter, such as the luminance or the luminous intensity of a light source of a motor vehicle, so that it can be seen and seen as required without use more resources than necessary and without dazzling other users. It may be as well to control a lighting device that a vehicle signaling device. As examples, for example, the headlights of the vehicle, or the daytime running lights or DRL for "Daytime Running Light" in English, these include diodes, or the front fog lamps, but also the rear fog lamps or turn signals or brake lights. With regard to the "to be seen" aspect, the principle used is the contrast sensitivity of the human eye, which defines the minimum contrast needed on an object in a background to be detected by the human eye. The contrast is defined by the ratio of the luminance difference between the object and the background, on the luminance of the background; it is the law (1) of Weber-Fechner which defines the contrast Cw as follows: (1) (where L = the luminance of the object, and Lfond = the luminance of the background). The invention relates to the possibility of modulating the luminance of a light source of a motor vehicle, so as to achieve a contrast sufficient to be VU. In the present, it is considered that to be visible the contrast must be greater than or equal to a predetermined threshold of 5% contrast. The invention also makes it possible, for example, to adapt the luminance of the light source as a function of the required visibility distance. The principle of the invention can also be applied to the loss of visibility due to fog or for example to the snow, or at nightfall.

An adaptation system 1 of the vehicle for controlling the modulation or adjustment of photometric parameter of a light source of the vehicle is now described. Adaptation system FIG. 1 schematically shows an adaptation system 1 making it possible to adapt at least one photometric parameter of a light source of the vehicle. In particular, this system 1 makes it possible to adapt the luminance of one or more light sources of the vehicle and comprises for this purpose at least one processing means. By way of example, the system 1 comprises data acquisition means 3, data processing means 5, and a control device 7 for the light sources of the vehicle. The data acquisition means 3 can comprise, for example, one or more cameras 9 for taking up images of the environment of the vehicle, or more precisely of a road scene. A camera 9 may in particular be configured to measure the ambient luminance of the vehicle environment (or the level of illumination of the vehicle), for example by calibrating it beforehand with the aid of a photometer.

Alternatively or additionally, the data acquisition means 3 may comprise a twilight sensor 11 otherwise known as a "twilight sensor" in English. This twilight sensor 11 may in particular be able to measure the ambient luminance of the vehicle environment or the level of illumination to which the vehicle is subjected, this illumination being generated by the vehicle environment.

These data acquisition means 3 may alternatively or additionally comprise one or more infrared sensors 13 capable in particular of measuring the ambient luminance of the vehicle environment or the level of illumination of the vehicle. The data acquisition means 3 may also comprise one or more speed sensors 15 of the vehicle for measuring the real speed of the vehicle or means 17 for detecting a speed limitation. These means 17 are for example connected to a system 19 for driver assistance or ADAS for "Advanced Driver Assistance System" in English, and / or navigation such as a GPS for "Global Positioning System" in English. The means 17 10 are then configured to read a speed information from the driver assistance system said ADAS and / or GPS navigation system. These means 17 may also possibly be configured to measure the relative speed of the vehicle relative to other road users using a vehicle detection system for example or a system of "forward collision warning" or still "headway monitoring" or so called "anticollision". Finally, the data acquisition means 3 may comprise at least one means for detecting the presence of a parameter that disturbs the visibility of the vehicle environment. By way of example, there may be mentioned a fog detection means 21, or a twilight sensor 11 capable of detecting a transition between day and night, or a means of detecting snow or rain, or more generally a measurement sensor of visibility distance. The data processing means 5 of the system may comprise at least one image processing means 23 to which a read image is transmitted, for example to read speed information by analyzing a transmitted image and identifying a limitation. speed on a speed limit sign. Alternatively or additionally, the data processing means 5 may comprise at least one means for determining a value of the luminance of the light source characteristic of a contrast greater than a predetermined threshold of contrast between the light source. and the environment of the vehicle, such as a computer or a reading means of a predefined graph such as an abacus or a table of correspondences. In the latter case, the system 1 comprises at least one graph storage means, or also predetermined correspondence tables. The data processing means 5 further comprise at least one calculation means 27 for the required visibility distance at which a speed information is transmitted. The data processing means 5 may also include at least one processing means 29 for determining the visibility distance when a visibility disturbing parameter has been detected, such as fog, snow, rain or night. Finally, the control device 7 of the light source is connected to at least one processing means of the system 1 and is configured to adjust a photometric parameter of a light source of the vehicle according to data transmitted by the processing means 5 such as required sight distance, or reduced visibility distance due to nightfall, or fog density. The control device 7 comprises one or more transmitters of control signals for the light sources to be modulated. A control signal can control the adjustment of the luminance value of the light source so as to achieve a determined luminance value characteristic of a minimum contrast with the vehicle environment. A control signal may alternatively or additionally control the adjustment of at least one photometric parameter of a light source according to a calculated required viewing distance. It is also possible that a control signal can control the switching on or off, and / or the luminance of a light source according to visibility thresholds on the visibility distance. According to an alternative embodiment, the control device 7 may comprise a means of inhibiting the driving of the high beam when fog is detected. An adaptation method is described, for example implemented by such an adaptation system 1, and for modulating at least one photometric parameter of one or more light sources of the vehicle. First Embodiment: Day In daytime conditions, the photometric parameter adaptation method comprises the following steps: in a step E 1, a value of the luminance of at least a part of the environment of the vehicle or the level of illumination to which the vehicle is subjected, from the determined value, for example of the luminance of at least a part of the environment or the level of illumination of the vehicle, it is determined at step E2, a value of the luminance of the light source characteristic of a contrast greater than a predetermined threshold of contrast between the light source and the environment of the vehicle, and in step E3 the value of the luminance of the vehicle is adjusted; light source so as to reach the value of the characteristic luminance determined. These steps are diagrammatically represented on the graph of FIG. 2. According to this first day-time embodiment, for example, the luminance of the so-called DRL daytime lights is adjusted. As used herein, ambient luminance means the luminance of the vehicle environment. The ambient luminance is for example measured by a twilight sensor 11 of the adaptation system 1 of the vehicle. The ambient luminance can also be determined by means of a camera 9. To do this, the camera 9 can be calibrated beforehand with the aid of a photometer capable of measuring at least one photometric quantity, in order to establish correspondences between a measurement made by the camera 9 of a luminous flux and the photometric quantity associated with the luminous flux measured by the photometer. As a variant, the ambient luminance may be measured by an infrared sensor 13, for example of the system 1. Alternatively or in addition, any other value representative of the illumination to which the vehicle is subjected may be taken into account in order to adjust the luminance of DRL daytime lights. By way of example, mention may be made of RLT (rain light tunnel) type rain sensors which incorporate a measure of ambient light, below a threshold corresponding to dawn or dusk. In this case it can be expected that the dipped beam are automatically switched on. In addition to this device, the device DRL can be controlled proportionally to the ambient brightness. The intensity of the DRL is defined at least for the light intensity corresponding to the detection threshold "day", and maximum for a light intensity corresponding to a significant amount of sunshine called "full sun". Based on the ambient luminance, the luminance of the DRLs needed for the vehicle to be seen can be calculated. This calculation can be done for example by a data processing means 25 of the system 1 such as a computer. To do this, starting from the formula (1) of the contrast defined above, Lambient of the vehicle; LDRL = the luminance of DRL; and Lambient = the ambient luminance of the vehicle environment), the value of the luminance of the object, here the DRL, is determined to obtain the desired contrast value according to formula (2): (2) L DRL = Laminate * (1+ C) The LDRL value obtained from the luminance of the DRL is therefore characteristic of a sufficient contrast to be visible, namely at least 5%. (1) C DRL = LDRL Lambient (where CDRL = contrast of the DRL compared to the environment -14- According to an alternative to the calculation, one can read a predefined graph of correspondences between values of the environmental luminance of the environment of the vehicle and luminance values of the light source characteristics of a 5% contrast according to the embodiment described.

According to this alternative, the method comprises a preliminary step in which a correspondence graph is established between values of the ambient luminance of the vehicle environment and the luminance values of the light source, here the DRL, which are characteristic of a contrast greater than the predetermined threshold of contrast, in this case 5%, between the light source and the environment of the vehicle.

This correspondence graph is for example made in the form of an abacus. This graph can be done by experiment or simulation. Thus, from the ambient luminance of the environment of the vehicle Lam bient determined, can be read on the graph such as an abacus, the value of the LDRL luminance of the DRL characteristic of a CDRL contrast of 5% between the DRL and the vehicle environment for the vehicle to be visible. The method can, in addition to the light emanating from the sky, also take into account the illumination of the road for example by the street lights and thus the luminance of the road, to determine the adequate luminance of the DRL. In this case, it is particularly possible to record a road scene, for example using a camera 9, and to define different areas of the image. For example, we can define a first part "horizon" and a second part "road" taking into account the lighting of the road and the sides of the road. Once the characteristic value of the luminance LoLL of the DRL read or calculated for example, a control signal for adjusting the luminance of the DRL can be emitted. This signal is for example transmitted by a transmitter of the control device 7 of the system 1. The luminance of the daytime running lights DRL is thus automatically adapted to the need of the vehicle to be seen without dazzling the other users, and by saving power consumption. This control of the adjustment of at least one photometric parameter, such as the luminance of the DRLs in this first embodiment, can be done continuously by pulse width modulation or PWM for "Pulse Width Modulation". English. The luminance of the DRLs can therefore be controlled by a pulse modulation that controls the voltage applied to the DRLs, which affects the electrical energy supplied and the effects of the brightness intensity. According to an alternative, the adjustment of at least one photometric parameter, such as luminance, in steps can be controlled. Indeed, it can be provided to define one or more thresholds of ambient luminance for delimiting steps; and for each step, a luminance characteristic value of the associated DRLs. In order to illustrate this stepwise control, there is shown diagrammatically and simplified in FIG. 3 an axis of the Lambient ambient luminance and an axis of the luminance of the corresponding LDRL DRLs. In particular, it is possible to provide a preliminary step in which, for example, a first threshold S1 of ambient luminance and a second threshold S2 of ambient luminance are defined, and for each stage a luminance value of the DRLs ipu, "__, DRL2 The luminance values of the LDRL1, LDRL2 and LDRL3 DRLs are of course determined so that the contrast is greater than 5% relative to the ambient luminance in the steps defined by the thresholds S1, S2. In this case, the method comprises a step of comparing the determined ambient luminance with the ambient luminance thresholds above the first threshold S1 of ambient luminance, that is to say when the determined ambient luminance is greater than the first threshold S1. , the associated luminance of the DRLs must be of the order of Leu, the luminance of the DRLs is compared with the value LnRLI, and if the values differ, the luminance of the DRLs is adjusted so as to reach the value IeRu. that the ambient luminance determined is lower than the first threshold S1 and greater than the second threshold S2, the luminance of the DRLs is compared with the value LDRI29 and if the values differ, the luminance of the DRLs is adjusted so as to reach the value LDRL2. And, below the second threshold S2 of ambient luminance, that is to say when the determined ambient luminance is lower than the second threshold S2, the luminance of the DRLs is compared with the value LoRL3, and if the values differ, the luminance is adjusted. DRLs to achieve the LDRL3 value. In addition, the luminance of the DRLs can be adjusted according to a required visibility distance Dg. Referring to FIG. 4, the method then comprises the following steps: at least one speed information V is ascertained in step E4. In step E5, a required visibility distance 12 is calculated as a function of the speed. In step V, at least one photometric parameter is determined in step E6, in this case the luminance of the light source, the DRL according to this embodiment, as a function of the calculated required visibility distance, and control is required. step E7 the adjustment of the luminance of the DRL, according to the required visibility distance l2g_calculated. The speed information V relates for example to a speed limitation. This speed limitation can be read by an acquisition means of the system 1 such as a camera 9, and then determined by a processing means 23 of the system 1 to identify, for example, the speed limitation written on a control panel. This speed limitation information may also come from a driver assistance system 19 or ADAS for "Advanced Driver Assistance System" in English. Again, this speed limitation information may come from a navigation system such as a GPS for Global Positioning System. The speed information V recorded can also relate to the actual speed of the vehicle, read with at least one speed sensor 15 of the vehicle. If the speed limit is not available, the required sight distance 211 is calculated from the actual vehicle speed information. When the speed limitation information and the actual vehicle speed information are both available, the two speed information is compared, and if the actual speed is greater than the speed limit, the required visibility distance is calculated. from the actual speed. This visibility distance necessary to be seen by the other road users can be fixed by the reaction time: 1 "i necessary to react to the detection of an obstacle on the road, typically two seconds (this reaction time varies nevertheless from one driver to the other), and the speed of the vehicle, which corresponds to the speed of the vehicle during the reaction time T. The distance traveled during the reaction time TR is generally multiplied by two for a vehicle coming from in the opposite direction, assuming that both vehicles drive at the speed limit of the road, so as to avoid the collision between the two vehicles.The reaction time III gives us the reaction distance of the driver ph 20 At this distance the braking distance during which the driver brakes effectively must be added, the addition of these two distances gives the stopping distance of the vehicle for a given initial speed and For example, the stopping distance of a vehicle on a national road with a speed of about 90km / h, a deceleration of 6m / s2 and a reaction time of 2 seconds is 77m. . If the system is equipped with a measuring device, for example called "Time to collision", measuring in particular speed and acceleration characteristics of the vehicles arriving in front, the stopping distance can be adjusted in real time taking into account 30 counts the speed and acceleration characteristics of other road users. In order to take into account the speed of the two vehicles, the speed of each vehicle, available directly in its own vehicle, calculated by a distance / speed measuring device for the other vehicle is required. It can also be used a communication device, called "car to car", to exchange this data: in this case each vehicle emits its position, its speed to make it available to other road users. In the opposite case, it is considered that all road users drive at the legal speeds permitted, and an abacus is applied to know in real time the minimum visibility distance required for safe driving. This visibility distance Dy is for example fixed such that the visibility distance is greater than twice the stopping distance of the vehicle, according to formula (3) below: (3) Dv> 2xDA (with DA = distance d stopping the vehicle). A control signal for adjusting the luminance of the DRLs can then be emitted. This signal is for example emitted by a transmitter of the control device 7. The luminance of the DRL is thus automatically adapted according to the required visibility distance 12h. The increase in the luminance of the DRL can be done according to a predefined correspondence table between the required visibility distance j and the luminance of the LDRL DRLs or by reading on a predefined graph such as an abacus, or a table of predefined matches. Thus, the brightness of the DRL can be adjusted at the same time according to the speed 25 V and according to the ambient luminance Lain of the environment of the vehicle. This is represented schematically by the graph of FIG. 5. In this case, the steps E 1 for determining the ambient luminance kambient of the vehicle environment, and the steps E4 and E5 for determining the required visibility distance DL can to be done in parallel or successively. The steps E2 and E6 for determining the luminance of the DRL are then one and the same step. Similarly, the adjustment in step E3 and E7 is the same step. FIG. 5 diagrammatically and simplifiedly illustrates a graph of visibility curves as a function of the ambient luminance of the vehicle environment, for example a curve (C1) of visibility in sunny weather, a curve 5 (C2) visibility in cloudy weather, and a visibility curve (C3) at sunrise. Thus, according to the ambient luminance of the dawn to the fully sunny day through the cloudy state, the corresponding visibility curve can be selected. In addition, the value of the luminance of the DRL also takes into account the required visibility distance depending on the type of road, for example between a first required visibility distance Dei for example in an urban environment, and a second required visibility distance. 1: _k for example on rural roads which is therefore more important than in urban areas because the speed limit is higher. The luminance of the DRLs is therefore adapted according to necessity, by reducing the electrical consumption, while keeping the security, and by avoiding the dazzle of the vehicles arriving in the opposite direction. As said before, the adjustment can be done by continuous control by modulation of pulse widths or alternatively stepwise. According to an alternative embodiment, the control of the adjustment of a photometric parameter of the DRL can be done directly from the speed information V recorded, whether it is the limitation of speed or the speed the vehicle if the speed limit is not available or is less than the actual speed of the vehicle. For this, the luminance of the DRLs is adapted according to the speed information V according to a predefined graph such as an abacus, or a predefined table of correspondences between the speed V and the luminance of the DRL LDRL. As mentioned above, the luminance adjustment of the DRLs can be done by continuous control by modulation of pulse widths or alternatively by steps. With regard to the stepwise control, it is possible in particular to define speed thresholds V1, V2 for example associated with the type of road, and for each level defined by these thresholds an associated luminance value LDRuo, LoRL, 20, LDRL30 (see Figure 6). In this case, the method comprises a preliminary step for defining these steps and the appropriate luminance values. This is for example done by experiment or simulation. By way of example, the first speed threshold V1 is of the order of 50 km / h. The first speed threshold V1 therefore makes it possible to define a first landing associated with an urban environment and for which the luminance of the DRLs must be of the order of LDRI, 10. This value is, for example, 50% of the power of the DRLs. The second speed threshold V2 makes it possible to define a second level between the first threshold V1 and the second threshold V2. For this second stage the luminance of the DRL must be of the order of LDRI, 20. This value is in our example greater than 50% of the power of the DRL. And, above the second speed threshold V2, for example 130 km / h, a third step is defined for which the luminance of the DRL must be of the order of Lon ". This value is for example 100% of the power of the DRLs. Of course, it is possible to define less or more speed thresholds to define steps respectively associated with a luminance value of the DRLs. As previously said, it is therefore possible to adjust the brightness of the DRLs at a time as a function of the speed and according to the ambient luminance of the vehicle environment, but according to this variant the step E5 to determine the required visibility distance. DI! no longer necessary. Furthermore, in addition to the adaptation of the luminance of the DRLs as a function of the ambient luminosity and advantageously of the speed, the principle of adapting a photometric parameter of one or more light sources of the vehicle may also be applied to the loss of visibility due to fog or even to the snow. Thus, the method comprises a step in which the presence of a parameter disturbing the visibility is detected. With reference to FIG. 7, the case of presence of fog is described. Of course, the method also applies in case of snow. In step E8, the presence of fog disturbing the visibility is thus detected.

This fog detection can be done in particular with the aid of a fog sensor 21 of the vehicle system 1, or with the aid of a camera 9. The fog sensor 21 can use the principle of feedback. diffusion of an infrared light on the droplets of fog. It is for example installed in a rear light of the vehicle.

Alternatively, the fog sensor 21 can measure the flight time of photons, used in particular in LIDAR type anti-collision systems for "Light Detection and Ranging" in English, to evaluate the transmission of the atmosphere and therefore to deduce the presence of fog. According to another alternative, a camera 9 can record an image of the environment of the vehicle, and the fog sensor 21 may comprise at least one processing means for determining an average contrast value of at least a portion of the image identified, and determine depending on the result the presence or absence of fog.

In the event of fog, the visibility is disturbed, and the visibility distance decreases because of the atmospheric disturbance. The objective is to turn on and off the fog lamps when necessary, and to adapt at least one photometric parameter of lights such as turn signals, brake lights, fog lights.

Thus, following the detection of the presence of fog, there may be a step in which it controls the automatic ignition of at least one fog light source, such as a front fog light and / or rear. This makes it possible to meet the current regulation which imposes a fixed luminance for the function of the fog lamps, and an automatic ignition mode fog lamps below a visibility distance of eg 50m. Alternatively, it can be provided to issue an alert signal to warn the driver of the presence of fog and encourage him to manually turn on the front and / or rear fog lights. To do this, the visibility distance Dv is evaluated in the step E9, and the visibility distance Dv evaluated at at least one predefined visibility threshold Dv1, Dv2 is compared with the step E10. The visibility distance Dv can in known manner be evaluated as a function of the luminance of at least a part of a road scene image taken in the driver's field of vision or alternatively by producing and analyzing a curve of brightness of a raised road scene image. The first visibility threshold Dvi is for example at 50m and the second visibility threshold Dv2 may for example be 200m. For example, it can be provided that when the visibility distance Dv is below the visibility threshold Dv2, the fog lamps are on and when the visibility distance Dy is greater than the visibility threshold Dv2, the fog lamps are not lit or are extinguished. A different visibility threshold can also be provided for the front fog lamps, for example the threshold Dv2, and the rear fog lamps, for example the threshold DV2 '. Moreover, the density of fog can be detected; the denser the fog, the lower the visibility distance. For this, the method may comprise a preliminary step in which at least one visibility threshold is associated with a fog density. According to the example described: for a visibility distance less than the first visibility threshold Dvi, for example at 50m, the fog is of high density, for a visibility distance between the first Dvi and the second threshold Dv2, for example at 200m, the fog is of medium density, and -23- for a visibility distance greater than the second visibility threshold Dy2 the fog is of low density. Depending on the thresholds defined on the visibility distance, corresponding to the density of fog, it can be decided to turn on or off the dipped headlamps, fog lights front and / or rear. Thus, in step Ell, the automatic lighting of a front and / or rear fog lamp is controlled, or a fog detection warning signal is emitted so as to induce the driver to manually turn on the front fog lamps and / or back. In case of fog detection, another objective is to avoid high beam, and therefore in fog mode, the method may include for this purpose a step of inhibiting the driving of high beam. Moreover, in order to adapt the lighting to the loss of visibility due to fog, it is possible in step E12 to determine the light intensity I of the headlights according to the fog. If the visibility distance is less than at least one predefined visibility threshold, controlling the adjustment of at least one photometric parameter, for example the luminous intensity I, of the light source as a function of the visibility distance Dv. As mentioned above, the fog density can be detected, and the light intensity I can be increased as a function of this fog density; the denser the fog, the lower the visibility distance, and the higher the luminous intensity I of the headlights. This is schematically represented by the graph of FIG. 7 at step E12. The luminous intensity of the lights I can be increased, according to a table of 25 predefined matches between the visibility distance Dv or the density of fog and the luminous intensity I. The luminous intensity I can be increased proportionally to the distance reduced visibility, by a given factor. It is therefore an option for intelligent lights, keeping a luminance proportional to the disturbance in order to keep a constant visibility distance for the other vehicles. A control signal to adapt the photometry of the fog lamps can then optionally be issued. This signal is for example emitted by a transmitter of the control device.

The photometry of the fog lamps is automatically adapted to the loss of visibility due to fog. Of course, the control signal may also make it possible to adapt the light intensity of the vehicle's signaling devices, such as turn signals or brake lights.

Of course, similarly to the first embodiment, the required visibility distance Dg is to be adapted according to the type of road, namely urban environment or country roads, and proportionally the light intensity of the lights. Thus, as shown schematically in FIG. 7, steps E4 for reading speed information V and E5 to calculate the required visibility distance DR can also be implemented in this second embodiment. Therefore, in step E12, the appropriate light intensity of the lights is determined according to the required visibility distance 12R calculated. This adjustment can be made according to a predefined correspondence table between the required visibility distance and the intensity of the lights or by reading on a predefined graph such as an abacus, or a predefined correspondence table. FIG. 7 schematically and simplified a graph of visibility curves as a function of the ambient luminance of the vehicle environment, for example a visibility curve (Cl ') for the day, and a curve (C2 ') of visibility for the night. Thus, depending on the ambient environment from night to day, and according to the required visibility distance 121, the corresponding visibility curve can be selected. As for the first embodiment, the adjustment can be by continuous control by modulation of pulse widths or alternatively stepwise. Moreover, the visibility distance of a light source is fixed by calculating its contrast with respect to the luminance of the background of the scene.

The contrast required to judge the visibility of a light source is called apparent contrast. This contrast is calculated according to the formula (1) recalled above and takes into account the transmission of the atmosphere. The visibility distance of a light source calculated in real time by the adaptation system can be exploited to determine the extinction coefficient of the atmosphere. The extinction coefficient makes it possible to measure the loss of light radiation. According to an alternative embodiment, the luminance of the light sources is therefore modified as a function of this extinction coefficient of the atmosphere to obtain a visibility distance Dv, in the sense: necessary to be seen, at least greater than twice the stopping distance DAdu vehicle. Furthermore, according to an alternative embodiment, the control of the fog lamps lighting and / or the adjustment of a photometric parameter of the lights can be done directly from the V speed information noted. For example, when the detected speed V is less than or equal to a speed threshold of the order of 50km / h for example, it is determined that it is an urban driving and the front fog lights and rear can be automatically turned off to avoid dazzling other users. Alternatively or additionally, in order to determine whether the vehicle is in town for example, one or more information other than the speed information may be taken into account. For example, a location data of the vehicle can be studied; this location data can be transmitted by a GPS system or an ADAS driving assistance system. It is also possible to define stages according to speed thresholds and adequate values of light intensity of the lights. This is for example done by experiment or simulation.

Furthermore, there may be a traffic jam detection step and the transmission of a control signal to extinguish the front fog lights, when a traffic jam is detected. One can also consider a function called "courtesy", according to which the passing lights at a stop, at a red light, are stopped. The "courtesy" feature on the rear fog lights can be safely achieved by adding a rear distance sensor, such as a camera, infra-red, ultra-sound or radar). When a vehicle follows, at a standstill or at low speed, the rear fog lamp may be extinguished.

Second embodiment: Night Another parameter disrupting visibility is especially at night. In this case, we detect a transition between day and night. This detection can be done using a twilight sensor 11 from system 1 to step E101 (cf FIG. 8) in which a value of the luminance ka nabient of at least a part of the environment is determined. of the vehicle. Other models of night detection can be considered. This detection can be based in particular on the position of the sun relative to the position of the vehicle, or on the hour and the season.

In night mode, the method aims to turn on or off the low beam or high beam according to a threshold on the ambient brightness. It can be expected to turn on the main beam and turn off the low beam when the ambient luminance is below the preset threshold, and conversely to turn off the main beam and switch on the low beam when the ambient luminance is greater than the predefined threshold. In addition, the method aims to adapt the lighting level of the headlights at a time so that the driver of the vehicle can see the road and that other users can see the vehicle as a reference, depending on the need real lighting so as to limit the consumption of electrical energy and without dazzling other users. For this purpose, the method comprises the following steps: starting from the determined value of the luminance of at least part of the environment of the vehicle, a value of the luminance of the characteristic light source is determined in step E102 a contrast higher than a predetermined threshold of contrast between the light source and the image raised, and the value of the luminance of the light source is adjusted in step E103 so as to reach the value of the characteristic luminance determined. Namely, the luminance of the headlights is calculated, with a minimum of contrast with the measured ambient light of 5%. Steps E101 to E103 are similar to steps E1 to E3 of the first embodiment. Once the characteristic value of the luminance of the headlight is determined for a minimum contrast of 5%, for example by calculation or reading of an abacus, a control signal for adjusting the luminance of the headlights can be emitted. This signal is for example transmitted by a transmitter of the control device 7 of the system 1. To control the luminance of the headlights necessary to see, the method thus comprises the steps of determining the required visibility distance required, namely the following steps. In step E1, at least one speed information V is read, and in step E105 a required visibility distance D is calculated as a function of the speed information V. Moreover, during the night, can take into account the lighting emanating from the street lights, such as streetlights, which are usually sufficient to see, the luminance of the headlights can be set to a minimum. For this purpose, the luminance of the illumination of the road k is measured at the step E106. The visibility distance Dv is evaluated at the step E107 and the estimated visibility distance Dv is compared. at least one predefined visibility threshold, and if the visibility distance Dv is less than at least one predefined visibility threshold, determining in step E108 the adjustment of at least one photometric parameter of the light source as a function of the visibility distance Dv, before controlling in step E103 the adjustment of the luminance L of the headlight. More precisely, if the visibility distance Dv is less than the expected visibility according to the type of road, the luminance of the headlamp L is increased until the required visibility distance or required visibility distance 211 is reached. Similarly to the first embodiment, the speed information V can be used directly for calculating the correct luminance of the headlights, without calculating the required visibility distance DR.

For example, when an information of speed V less than or equal to 50 km / h is recorded, a driving in the city is considered, and it is estimated that, with the city light, the luminance of the headlights L can be set to a preset value. This predefined value is estimated from experiments or simulations. Similarly, it is possible to define different speed thresholds respectively associated with a type of road, and therefore with ambient lighting or not. For example, on country roads at 90 km / h, there is almost no ambient lighting and the luminance value of L headlights estimated from experiments or simulations, is greater than the estimated value for the city.

Furthermore, similarly to the first embodiment, the method can in night mode detect the presence of fog, and adjust the luminance of the headlights also as a function of the fog density. It will thus be understood that an adaptation method according to the invention makes it possible to adjust a photometric parameter of the vehicle light sources sufficiently to be seen and to see when necessary, saving electricity consumption. and avoid dazzling other users.

Claims (26)

REVENDICATIONS1. Method for adapting at least one photometric parameter of at least one lighting or signaling light source of a motor vehicle, characterized in that it comprises the following steps: a value representative of the illumination to which said vehicle generated by at least part of the environment of said vehicle is subjected, - from said value representative of the determined illumination, a value of the luminance of said light source (L, DRL; L) is determined; said luminance value (LDRL) being characteristic of a contrast greater than a predetermined threshold of contrast between said light source and the environment of said vehicle, and - the luminance value of said light source is adjusted so as to attain said characteristic luminance value determined. 2. Method according to claim 1, characterized in that a value of the luminance (LniMent) of at least part of the environment of said vehicle is determined, and from said determined value of luminance (La mbient) d at least a part of the environment of said vehicle, a value of the luminance of said light source (Lon; 3. Method according to one of claims 1 or 2, characterized in that the predetermined threshold of contrast is of the order of 5%. 4. Method according to any one of claims 1 to 3, characterized in that calculates said characteristic value of the luminance of said light source (LoLL; L) from said value representative of the illumination, and from of said predetermined threshold of contrast. 5. Method according to any one of claims 1 to 3, characterized in that it comprises: a preliminary step in which is established a graph of correspondence between values representative of the illumination to which said vehicle is subjected and luminance values of said light source (L, DRL, characteristics of a contrast greater than said predetermined contrast threshold, and - a step of reading said correspondence graph so as to determine the characteristic value of the luminance of said light source (Lp_i_u L) according to said determined value representative of the illumination to which said vehicle is subjected. 6. Method according to any one of the preceding claims, characterized in that it comprises the following steps: - at least one velocity information (V) is recorded, and the adjustment of at least one photometric parameter of said light source as a function of said measured speed information (V). 7. Method according to claim 6, characterized in that it comprises the following steps: - the required visibility distance (DR) is calculated as a function of said at least one speed information (V), and - the control is controlled adjusting at least one photometric parameter of said light source according to said calculated required visibility distance 8. Method according to one of claims 6 or 7, characterized in that one notes a speed limit information. 9. Method according to any one of claims 6 to 8, characterized in that one notes a real speed information of said vehicle. 10. The method of claim 8 taken in combination with claim 9, characterized in that it comprises the following steps: - comparing said speed limit and said actual speed, and - if the actual speed is greater than said limit of speed, the required visibility distance (LW) is calculated from said actual speed. 11. Method according to any one of the preceding claims, characterized in that it comprises the following steps: the visibility distance (Di) is calculated, from said calculated visibility distance (Dm), determined the atmospheric extinction coefficient, and the luminance of said light source is adapted according to said determined extinction coefficient. 12. The method of claim 11, characterized in that the luminance of said light source is adapted so as to obtain a visibility distance required to be seen, at least greater than twice the stopping distance of the vehicle. 13. Method according to any one of the preceding claims, characterized in that it comprises the following steps: detecting the presence of at least one parameter disturbing the visibility, the visibility distance (2y) is evaluated, the control is controlled. adjusting at least one photometric parameter of said light source according to said visibility distance (D i j. 14. The method of claim 13, characterized in that increases the light intensity of said light source (I), according to a predefined correspondence table between the visibility distance and the light intensity (I). 15. Method according to one of claims 13 or 14, characterized in that it comprises a step in which a transition between day and night is detected. 16. Method according to any one of claims 13 to 15, characterized in that it comprises a step in which the presence of fog is detected. 17. The method of claim 16, characterized in that controls the automatic ignition of at least one light source said anti-fog. 18. Method according to one of claims 16 or 17, characterized in that it comprises a step in which the ignition of high beam is inhibited. 19. A method according to any one of claims 16 to 18, characterized in that it comprises a preliminary step in which matches are defined between at least one visibility threshold and a fog density. 20. Method according to any one of claims 1 to 19, characterized in that controls the adjustment of at least one photometric parameter continuously by pulse width modulation. 21. Method according to any one of claims 1 to 19, characterized in that controls the adjustment of at least one step photometric parameter. 22. A system for adapting at least one photometric parameter of a lighting or signaling light source of a motor vehicle, for carrying out a method according to any one of the preceding claims, characterized in that what said system comprises: at least one processing means (9, 11, 13) for determining a value representative of the illumination to which said vehicle generated by at least part of the environment of the vehicle is subjected, at least one means processing device (25) for determining a value of the luminance of said light source characteristic of a contrast greater than a predetermined threshold of contrast between said light source and the environment of said vehicle, from said value representative of the determined illumination and a control device (7) of said light source connected to at least one processing means (3,5) and comprising a transmitter of a control signal for r adapting the luminance value of said light source so as to reach said determined characteristic luminance value 23. System according to claim 22, characterized in that said system comprises at least one processing means (15, 17, 23) for detecting a speed information, and in that said control signal is configured to adapt at least one photometric parameter of said light source according to said velocity information (V). 24. System according to one of claims 22 or 23, characterized in that: said system comprises: - at least one detection means (11,21) of the presence of a parameter disturbing the visibility of the environment of said vehicle , and - at least one processing means (29) for determining the visibility distance (Dy) when a parameter disturbing the visibility has been detected, and in that - said control signal is configured to control the ignition and / or adapting at least one photometric parameter of said light source according to the visibility distance 02y). 25. System according to claim 24, characterized in that said parameter disturbing the visibility of the environment of said vehicle may comprise at least one parameter of the group comprising: night, fog, snow, rain, smoke. 26. System according to any one of claims 22 to 25, characterized in that it is connected to a driving assistance system and / or a navigation system (19).