Method for automatic headlight calibration of a motor vehicle

Abstract

Method for automatic headlight calibration of a motor vehicle (1) wherein the following steps are performed in the motor vehicle (1): - a light distribution (LV) generated by a number of headlights (4) of the motor vehicle (1) on the ground in the vicinity of the motor vehicle (1) is captured by a camera (2) of the motor vehicle (1) at one or more times, thereby obtaining a number of camera images (KB); - in the number of camera images (KB) one or more camera images (KB') are identified by a computer means (3) of the motor vehicle (1) for which a number of conditions (BE) are fulfilled at the time of the acquisition of the respective camera image (KB'), wherein the number of conditions (BE) includes one or more driving conditions (FB) that each characterize a driving state of the motor vehicle (1) at the time of the acquisition of the respective camera image (KB'); - using the computer (3) one or more parameters (Δα) are determined which describe a difference between the current position of the number of headlights (4) relative to the motor vehicle (1), resulting from the identified camera image(s) (KB'), and the corresponding position according to a reference image (RB), wherein the reference image (RB) represents a target light distribution which is to be generated by the number of headlights (4) when the number of conditions (BE) are met, wherein, to determine the parameter(s) (Δα), one or more characteristics (CR) of the light distribution (LV) of the identified camera image(s) (KB') are compared with the respective characteristics of the target light distribution of the reference image (RB); - with the computer means (3) an actuator (5) of the motor vehicle (1) is controlled based on the parameter(s) (Δα) such that the actuator (5) positions the number of headlights (4) in the position according to the reference image (RB); characterized in that the number of conditions (BE) in addition to the driving conditions (FB) further includes one or more of the following conditions: - there are no external light sources and / or other road users in at least one part of the area surrounding the motor vehicle (1); - the inclination and / or surface condition of the ground on which the motor vehicle (1) is located remains unchanged within the range of the number of headlights (4).

Description

[0001] The invention relates to a method for the automatic headlight calibration of a motor vehicle and to a corresponding motor vehicle.

[0002] After a vehicle has been in operation for an extended period, the headlights often become misaligned, so that they no longer illuminate the vehicle's surroundings ideally, which can lead to glare for oncoming traffic. Traditionally, such misalignments are corrected manually during vehicle maintenance by measuring the light distribution of the headlight beam, for example, on a vertical wall in front of the headlights, and manually adjusting the headlights if there is a deviation from a reference light distribution.

[0003] Manually adjusting the headlights is time-consuming and has the disadvantage that misalignments are only detected during vehicle maintenance, which can lead to the vehicle being operated with misaligned headlights for a longer period of time.

[0004] Document DE 10 2011 109 440 A1 discloses a method according to the preamble of claim 1.

[0005] German patent application DE 10 2014 003 585 A1 discloses a method for adjusting the headlight of a vehicle traveling on a roadway. In the case of a level roadway in front of the vehicle, a pattern with a sharp light-dark boundary is projected onto a vertically oriented projection surface by means of the headlight. Image data is acquired from the generated pattern, from which a vertical distance between the horizon and the light-dark boundary of the generated pattern is determined. The headlight is then adjusted based on this determined vertical distance.

[0006] The publication DE 10 2012 110 377 A1 discloses a method for adaptive light-dark boundary detection for controlling the setting of a vehicle's headlight, in which image data of the light-dark boundary are captured and compared with a predefined data set, which is adapted based on state data of the vehicle's environment, which are determined with an environment sensor.

[0007] German patent application DE 10 2012 007 908 A1 describes a method for compensating for misalignment errors of a vehicle headlight. In this method, a light marking is projected onto an object outside the vehicle using the headlight, and an image of the light marking is captured by a camera. The same camera captures an image of the surroundings, and a target illumination level based on these surroundings is determined, taking illumination rules into account. Based on this target illumination level based on the surroundings and the captured image of the light marking, a target illumination level specific to the light marking is determined, which then serves as the basis for adjusting the headlight's beam pattern.

[0008] The object of the invention is to provide a method which enables automatic headlight calibration of a motor vehicle during operation.

[0009] This problem is solved by the method according to claim 1 or the motor vehicle according to claim 12. Further developments of the invention are defined in the dependent claims.

[0010] The method according to the invention serves for the automatic headlight calibration of a motor vehicle. The motor vehicle is preferably a passenger car, but it can also be a truck or another type of motor vehicle (e.g., a motorcycle). The following steps are carried out within the framework of the method according to the invention.

[0011] A light distribution (in particular a low-beam distribution) generated on the ground in the vicinity of the vehicle by a number of headlights of the motor vehicle (i.e., at least one headlight) is captured by a camera of the motor vehicle at one or more points in time, thereby obtaining a number of camera images. In other words, the corresponding camera images represent the light distribution of the headlight(s) on the ground. The number of headlights is preferably one or more, and in particular two, front headlights of the motor vehicle.

[0012] Within the number of camera images, one or more camera images are identified by a computer system within the vehicle, for which a number of conditions are met at the time the respective camera image is captured. These conditions include one or more driving conditions. Each driving condition characterizes a driving state of the vehicle at the time the respective camera image is captured. The term "computer system" is to be interpreted broadly. Specifically, it can refer to a single computer unit within the vehicle or, if applicable, to several computer units distributed throughout the vehicle.

[0013] According to the invention, one or more parameters are determined using computer means. These parameters describe the difference between the current position of the number of headlights relative to the vehicle, as determined by the identified camera image(s), and the corresponding position according to a reference image. The reference image represents a target light distribution, which is to be generated by the number of headlights when a number of conditions are met. In this sense, the target light distribution is a light distribution that represents the desired light distribution for the operation of the vehicle. To determine the parameter(s) mentioned above, the inventive method compares one or more characteristics of the light distribution of the identified camera image(s) with the respective characteristics of the target light distribution of the reference image.The characteristics can include any properties of the light distribution with regard to its brightness, position, or shape.

[0014] Finally, using the computer, an actuator of the motor vehicle is controlled based on the previously determined parameter(s) in such a way that the actuator positions the number of headlights in the position according to the reference image, i.e. the difference between the current position and the position according to the reference image is compensated for by appropriate control of the actuator.

[0015] The reference image processed in the inventive method can be determined in various ways. For example, the reference image can be determined experimentally beforehand using a camera in a motor vehicle, where the target light distribution is generated by the number of headlights and the required number of conditions are met. Alternatively, the reference image can be calculated appropriately. This calculation can incorporate, among other things, the bidirectional reflectance distribution function, which is known per se and describes the reflection behavior of a surface. To determine the reference image, a bidirectional reflectance distribution function for a common road surface material can be used to calculate the corresponding light distribution.This calculation also incorporates further parameters relating to the lighting characteristics of the headlights installed in the vehicle. By using a bidirectional reflectance distribution function and corresponding lighting characteristics of the vehicle headlights, reference images can be easily calculated for various vehicle types. Furthermore, it is possible to generate reference images for different scenarios, such as varying surface properties of the ground in the vicinity of the vehicle.

[0016] According to the invention, the number of conditions includes, in addition to the driving conditions, one or more and in particular all of the following conditions: - there are no external light sources and / or other road users in at least one area of ​​the vehicle's surroundings; - the inclination and / or surface condition of the ground on which the motor vehicle is located remains unchanged within the range of the number of headlights.

[0017] Preferably, the number of conditions also includes the following condition: - The ambient brightness around the vehicle is below a predetermined threshold.

[0018] The above term "surface texture" can refer to any characteristics of the ground surface. In particular, a change in surface texture also occurs when the ground's reflective properties change, for example, due to markings on the ground. The additional conditions defined above ensure particularly good comparability of the identified camera images with the reference image, thereby improving the reliability of determining the parameters for describing the difference in the headlight positions.

[0019] The method according to the invention has the advantage that the headlight alignment can be easily determined using a camera installed in the vehicle, and based on this, the headlight(s) can be automatically returned to their correct position. In this way, it can be ensured that the vehicle's headlights are permanently correctly adjusted. Furthermore, no manual adjustment of the headlights is required during vehicle maintenance.

[0020] In a preferred embodiment of the method according to the invention, the driving condition or conditions comprise one or more, and in particular all, of the following driving conditions: - the acceleration of the motor vehicle in its longitudinal direction is below a predetermined threshold; - the rotational speed of the motor vehicle around a transverse axis of the motor vehicle (so-called pitch rate) is below a predetermined threshold; - the rotational speed of the motor vehicle around a vertical axis of the motor vehicle (so-called yaw rate) is below a predetermined threshold.

[0021] The above conditions ensure that when the correspondingly identified camera image is captured, the vehicle is traveling at a constant speed or stationary and is not performing any yaw or pitch movements. This ensures good comparability of the light distributions in the identified camera images with the reference image.

[0022] In a further embodiment of the method according to the invention, the number of conditions is verified, at least partially, based on measurement data from one or more sensors in the motor vehicle. In particular, the above driving condition concerning the acceleration of the motor vehicle in its longitudinal direction can be verified using wheel speed sensors. Similarly, the above conditions concerning the rotational speed of the motor vehicle about a transverse axis or a vertical axis can be verified using corresponding yaw rate sensors in the motor vehicle.

[0023] In a further embodiment of the method according to the invention, the measurement data from the corresponding sensors contain one or more camera images captured by the camera. In other words, a sensor in the motor vehicle used to verify the number of conditions is the corresponding camera whose camera images are processed in the method according to the invention. For example, the camera images can be used to verify the condition that there are no external light sources or other road users in at least part of the motor vehicle's surroundings. Object recognition can optionally be used to identify the other road users.

[0024] In another variant, at least some of the above measurement data was recorded at one or more points in time that occurred after the time the respective camera image was captured. In particular, subsequent camera images can be used to analyze whether the slope or surface condition of the ground changes within the range of the number of spotlights.

[0025] In a further embodiment of the method according to the invention, the number of conditions is checked at least partially based on information from one or more external sources and / or based on information from a navigation system of the vehicle. An external source can be, for example, a backend system communicating with the vehicle or another road user in the vicinity of the vehicle that communicates with the vehicle.

[0026] In a further embodiment of the method according to the invention, the current position of the number of headlights relative to the vehicle is determined from several identified camera images, wherein this current position is determined by averaging the individual camera images of the several identified camera images. Preferably, the mean of the corresponding characteristics used for comparison with the reference image is used for averaging. Depending on the embodiment, the averaging can be carried out in different ways. In particular, it can be a weighted or unweighted averaging. The mean can also be defined differently. In particular, it can be the arithmetic mean or the median.

[0027] In a further embodiment of the method according to the invention, the parameter(s) comprise a difference in the rotation angle about a transverse axis of the motor vehicle and / or a difference in the rotation angle about a vertical axis of the motor vehicle. These parameters describe very well the adjustment of the headlights in a motor vehicle.

[0028] In a preferred embodiment of the invention, the light distribution is a low-beam distribution, and as a characteristic of the light distribution of the identified camera image(s), the position of a boundary of the low-beam distribution located remotely from the vehicle is determined. Preferably, this boundary corresponds to the illumination range of the low-beam distribution. The boundary can be defined by a suitable brightness threshold, as explained in more detail in the detailed description.

[0029] In a further embodiment, the light distribution detected in the method according to the invention is captured using a stereo camera. In other words, the captured camera images represent three-dimensional image information. The reference images are also stored as three-dimensional image information. This variant improves the reliability of comparing the characteristics between the identified camera images and the reference image.

[0030] In addition to the method described above, the invention relates to a motor vehicle comprising a camera, a number of headlights, a computer, and an actuator. In this motor vehicle, the camera is configured to capture a light distribution generated on the ground in the vicinity of the motor vehicle by the number of headlights at one or more points in time, thereby obtaining a number of camera images. Furthermore, the computer is configured to identify, among the number of captured camera images, one or more camera images for which a number of conditions are met at the time of capture of the respective camera image, wherein the number of conditions comprises one or more driving conditions, each of which characterizes a driving state of the motor vehicle at the time of capture of the respective camera image.Furthermore, the number of conditions includes, in addition to the driving conditions, one or more and in particular all of the following conditions: - there are no external light sources and / or other road users in at least one area of ​​the vehicle's surroundings; - the inclination and / or surface condition of the ground on which the motor vehicle is located remains unchanged within the range of the number of headlights.

[0031] Furthermore, the computer is configured to determine one or more parameters that describe a difference between the current position of the number of headlights relative to the vehicle, as determined by the identified camera image(s), and the corresponding position according to a reference image, wherein the reference image represents a target light distribution to be generated by the number of headlights when the number of conditions are met, and wherein, to determine the parameter(s), one or more characteristics of the light distribution of the identified camera image(s) are compared with the respective characteristics of the target light distribution of the reference image.

[0032] The computer is further configured to control the motor vehicle's actuators based on the parameter(s) in such a way that the actuators position the number of headlights according to the reference image.

[0033] The motor vehicle according to the invention is preferably equipped to carry out one or more preferred variants of the method according to the invention.

[0034] An embodiment of the invention is described in detail below with reference to the accompanying figures.

[0035] They show: Fig. 1 a schematic representation of a motor vehicle in which a variant of the method according to the invention is carried out; and Fig. 2. A flowchart illustrating the steps of the variant of the procedure, which is used in the motor vehicle of the Fig. 1 is carried out.

[0036] An embodiment of the method according to the invention is described below with reference to the one in Fig. The passenger car 1 shown in section 1 is explained. The passenger car 1 includes a camera 2 behind the windshield, which serves to capture the light distribution generated by the vehicle's headlights. Depending on the design, the camera can be a 2D camera or a stereo camera. Two headlights 4 are provided to generate the headlight beam, from which Fig. 1 only one is visible. When carrying out the method according to the invention, the headlights 4 generate low beam, which results in the light distribution LV on the ground in front of the vehicle. This light distribution is only schematically indicated by a dashed line. The rear edge E of the light distribution, which corresponds to the illumination range of the low beam, is designated by reference numeral E.

[0037] To implement the embodiment described here, a control unit 3, shown only schematically, is installed in the motor vehicle 1. The function of the control unit can optionally be distributed across several different components in the motor vehicle. The control unit represents an embodiment of a computing device as defined in the claims. An actuator 5 is controlled via the control unit 3, which adjusts the headlights 4, thereby changing their position relative to the motor vehicle. In the embodiment described here, calibration of the headlight position is performed solely with respect to an adjustment of the pitch angle of the motor vehicle. The pitch angle describes the rotation about a transverse axis Q of the motor vehicle. This transverse axis, which is located in Fig. The line 1, indicated by a dot, runs perpendicular to the plane of the sheet. The pitch angle itself is denoted by the reference symbol α.

[0038] The steps performed to calibrate the headlights of motor vehicle 1 are described below using the following examples: Fig. Section 2 explains. Headlight calibration can be initiated by the vehicle user or, if applicable, automatically. According to step S1, the light distribution LV of the vehicle is recorded at regular intervals during operation with the low beams switched on using camera 2. In this way, a large number of camera images KB are obtained at different times.

[0039] According to step S2, a camera image KB' is identified from the camera images KB for which conditions BE, comprising driving conditions FB, are fulfilled. The driving conditions describe the driving state of the motor vehicle at the time the camera image KB' is captured. In the embodiment described here, the driving conditions FB relate to the following three conditions: - the acceleration of the motor vehicle in its longitudinal direction is below a predetermined threshold; - the pitch rate of the motor vehicle about the transverse axis Q is below a predetermined threshold; - the yaw rate of the vehicle about a vertical axis is below a predetermined threshold.

[0040] These conditions can be verified in any way using suitable sensors in the vehicle. To verify the condition relating to the vehicle's longitudinal acceleration, wheel speed sensors installed in the vehicle are preferably used. To verify the condition relating to the pitch rate and yaw rate, yaw rate sensors installed in the vehicle are preferably used.

[0041] In addition to the aforementioned driving conditions FB, further conditions are checked that must be met when the camera image KB' is captured. The following additional conditions are taken into account in the embodiment described here: - there are no external light sources and / or other road users in the direction of travel in front of the vehicle; - the ambient brightness around the vehicle is below a predetermined threshold; - the slope and surface condition of the ground on which the motor vehicle is driving remains unchanged within the range of the headlight beam (given by edge E).

[0042] These conditions can then be verified using suitable sensors in the vehicle. In a preferred configuration, the camera images captured by camera 2 are used. This allows, for example, the determination of whether external light sources or road users are in front of the vehicle. The presence of road users can be determined using suitable object detection in the vehicle. Furthermore, to determine the slope or surface texture of the ground, camera images acquired after the image for which the conditions are currently being verified can be used. The slope or surface texture can then be deduced from the changes in light distribution in successive camera images.If the incline increases in an uphill direction, for example, this leads to a change in the camera images such that the edge E of the light distribution in the camera images moves upwards.

[0043] After identifying a corresponding camera image KB' for which the conditions BE are met, step S3 of the Fig. 2. Determining a pitch angle deviation Δα, taking into account a reference image RB stored in the vehicle. The reference image RB corresponds to a camera image representing a target light distribution of the headlight beam under the conditions BE described above. The target light distribution represents the ideal low beam light distribution specified for the respective vehicle. The corresponding reference image RB can be determined in various ways. In particular, it can be obtained experimentally beforehand by taking a camera image under the predetermined conditions. Alternatively, the reference image can also be calculated in a suitable manner, e.g., using the bidirectional reflectance distribution function for a common asphalt surface described above.

[0044] To compare the camera image KB' with the reference image RB, the position of the edge E, and thus the illumination range of the low beam distribution, is determined in both the camera image and the reference image as a characteristic CR of the light distributions of the respective images. The determination of the edge E in the corresponding images is preferably achieved by defining a brightness threshold, as the edge is characterized by a significant drop in light intensity. In other words, the edge is detected at a position where the light distribution in the vertical direction of the image falls below the brightness threshold. Should the illumination ranges differ between camera image KB' and reference image RB, it can be concluded that the headlights are not ideally adjusted according to the target light distribution of the reference image RB.

[0045] In the event of a difference in the illumination ranges, the pitch angle deviation Δα is then determined using known calculation methods; that is, the difference between the pitch angle corresponding to the reference image RB and the actual pitch angle corresponding to the camera image KB'. Based on this pitch angle deviation, the following then occurs in step S4 of the Fig. 2 the actuator 5 is controlled in such a way that the pitch angle deviation is compensated, thereby automatically positioning the headlights into the ideal position in a simple manner and thus achieving headlight calibration.

[0046] The invention was previously described based on headlight calibration using a single identified camera image. However, multiple such camera images, which meet the relevant conditions, can also be used for headlight calibration. For example, to determine the pitch angle deviation, an average is calculated across the multiple identified camera images. During this averaging process, the mean range of the light output in the identified camera images is determined and compared with the corresponding range in the reference image. As mentioned above, the averaging can be performed differently depending on the specific implementation of the method. In particular, it can be an unweighted or, if necessary, a weighted average. The mean value can be, for example, the median or, if necessary, the arithmetic mean.

[0047] The embodiment of the invention described above has a number of advantages. In particular, it provides, for the first time, automatic headlight calibration during the operation of a motor vehicle by evaluating camera images. In this way, the headlight beam can always be ideally adjusted without the need for manual checking and adjustment of the headlight position. Reference symbol list 1 motor vehicle 2 cameras 3 Control unit 4 headlights 5 Actuators LV light distribution E Edge of the light distribution Q transverse axis of the motor vehicle α Pitch angle KB camera image KB' identified camera image BE conditions FB Driving Conditions RB Reference Image CR characteristic Δα Pitch angle deviation

Claims

[1] Method for automatic headlight calibration of a motor vehicle (1) wherein the following steps are carried out in the motor vehicle (1): - a light distribution (LV) generated by a number of headlights (4) of the motor vehicle (1) on the ground in the vicinity of the motor vehicle (1) is captured by a camera (2) of the motor vehicle (1) at one or more times, thereby obtaining a number of camera images (KB); - in the number of camera images (KB) one or more camera images (KB') are identified by a computer means (3) of the motor vehicle (1) for which a number of conditions (BE) are fulfilled at the time of the acquisition of the respective camera image (KB'), wherein the number of conditions (BE) includes one or more driving conditions (FB) that each characterize a driving state of the motor vehicle (1) at the time of the acquisition of the respective camera image (KB'); - using the computer (3) one or more parameters (Δα) are determined which describe a difference between the current position of the number of headlights (4) relative to the motor vehicle (1), resulting from the identified camera image(s) (KB'), and the corresponding position according to a reference image (RB), wherein the reference image (RB) represents a target light distribution which is to be generated by the number of headlights (4) when the number of conditions (BE) are met, wherein, to determine the parameter(s) (Δα), one or more characteristics (CR) of the light distribution (LV) of the identified camera image(s) (KB') are compared with the respective characteristics of the target light distribution of the reference image (RB); - using the computer means (3) based on the parameter(s) (Δα) an actuator (5) of the motor vehicle (1) is controlled such that the actuator (5) positions the number of headlights (4) in the position according to the reference image (RB); characterized by , that the number of conditions (BE) in addition to the driving conditions (FB) also includes one or more of the following conditions: - there are no external light sources and / or other road users in at least one part of the area surrounding the motor vehicle (1); - the inclination and / or surface condition of the ground on which the motor vehicle (1) is located remains unchanged within the range of the number of headlights (4). [2] Method according to claim 1, characterized by , that the driving condition or driving conditions (DC) include one or more and in particular all of the following driving conditions: - the acceleration of the motor vehicle (1) in its longitudinal direction is below a predetermined threshold; - the rotational speed of the motor vehicle (1) about a transverse axis (Q) of the motor vehicle (1) is below a predetermined threshold; - the rotational speed of the motor vehicle (1) about a vertical axis of the motor vehicle (1) is below a predetermined threshold. [3] Method according to claim 1 or 2, characterized by , that the number of conditions (BE) further includes the following condition: - the ambient brightness around the motor vehicle (1) is below a predetermined threshold. [4] Method according to any one of the preceding claims, characterized by , that the number of conditions (BE) is verified at least partially based on measurement data from one or more sensors in the motor vehicle (1). [5] Method according to claim 4, characterized bythat the measurement data includes one or more camera images (KB) captured by the camera (2). [6] Method according to claim 4 or 5, characterized by , that at least some of the measurement data was recorded at one or more times that are later than the time of recording of the respective camera image (KB). [7] Method according to any one of the preceding claims, characterized by , that the number of conditions (BE) is checked at least partially based on information from one or more sources outside the vehicle and / or based on information from a navigation system of the motor vehicle (1). [8] Method according to any one of the preceding claims, characterized by, that the current position of the number of headlights (4) relative to the motor vehicle (1) results from several identified camera images (KB) and that this current position is determined by averaging the individual camera images (KB') of the several identified camera images (KB'). [9] Method according to any one of the preceding claims, characterized by , that the parameter(s) (Δα) include a difference in the rotation angle about a transverse axis (Q) of the motor vehicle (1) and / or a difference in the rotation angle about a vertical axis of the motor vehicle (1). [10] Method according to any one of the preceding claims, characterized by , that the light distribution (LV) is a low beam distribution and as a characteristic (CR) of the light distribution (LV) of the identified camera images (KB') the position of a boundary (E) of the low beam distribution located away from the motor vehicle is determined. [11] Method according to any one of the preceding claims, characterized by that the light distribution (LV) is captured using a stereo camera. [12] Motor vehicle comprising a camera (2), a number of headlights (4), a computing device (3) and an actuator (5), wherein - the camera (2) is configured to capture a light distribution (LV) generated by the number of headlights (4) of the motor vehicle (1) on the ground in the vicinity of the motor vehicle (1) at one or more times, thereby obtaining a number of camera images (KB); - the computing means (3) is configured to identify one or more camera images (KB') in the number of camera images (KB) for which a number of conditions (BE) are met at the time of acquisition of the respective camera image (KB'), wherein the number of conditions (BE) includes one or more driving conditions (FB) that each characterize a driving state of the motor vehicle (1) at the time of acquisition of the respective camera image (KB'); - the computing means (3) is configured to determine one or more parameters (Δα) which describe a difference between the current position of the number of headlights (4) relative to the motor vehicle (1), resulting from the identified camera image(s) (KB'), and the corresponding position according to a reference image (RB), wherein the reference image (RB) represents a target light distribution which is to be generated by the number of headlights (4) when the number of conditions (BE) are met, wherein, to determine the parameter(s) (Δα), one or more characteristics (CR) of the light distribution (LV) of the identified camera image(s) (KB') are compared with the respective characteristics of the target light distribution of the reference image (RB); - the computer means (3) is set up to control the actuator (5) of the motor vehicle (1) based on the parameter(s) (Δα) such that the actuator (5) positions the number of headlights (4) in the position according to the reference image (RB): characterized by , that the number of conditions (BE) in addition to the driving conditions (FB) further includes one or more and in particular all of the following conditions: - there are no external light sources and / or other road users in at least one part of the area surrounding the motor vehicle (1); - the inclination and / or surface condition of the ground on which the motor vehicle (1) is located remains unchanged within the range of the number of headlights (4). [13] Motor vehicle according to claim 12, characterized by , that the motor vehicle (1) is equipped to carry out a method according to one of claims 2 to 11.

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