DE102011081362A1 - Method for determining surface quality of track for passing vehicle, involves outputting surface state signal indicating surface condition of the track when the comparison signal satisfies predetermined relationship - Google Patents

Abstract

The method involves reading (210) a reflection signal (150) representing an intensity of light or color of light, from the environment (120) of the vehicle (100). The environment of the vehicle is illuminated using headlamp (130) of the vehicle. The reflection signal is compared (220) with reference signal (155) and/or value (167) stored in memory (165), for outputting a comparison signal. The surface state signal (175) indicating surface condition of the track (125) is outputted (230) when the comparison signal satisfies predetermined relationship. Independent claims are included for the following: (1) device for determining surface quality of track for passing vehicle; and (2) computer program product for determining surface quality of track for passing vehicle.

Description

State of the art

The present invention relates to a method for determining a surface condition of a road used by a vehicle or to be driven, to a corresponding device and to a corresponding computer program.

Many driver assistance systems adapt their behavior to the current weather situation or road situation. For example, it is advantageous if the intervention of an ESP system can be selected depending on the coefficient of friction of the road. This coefficient of friction may in turn depend on the wetness of the road. This coefficient of friction is detected by means of a traction monitoring unit in an anti-lock braking system, it is for example in the DE 10 2010 033 007 A1 is disclosed.

Disclosure of the invention

Against this background, the present invention proposes a method for determining a surface condition of a roadway traveled or driven by a vehicle, an apparatus which uses this method, and finally a corresponding computer program product according to the main claims. Advantageous embodiments emerge from the respective subclaims and the following description.

• – Einlesen eines Reflexionssignals, das eine Lichtintensität und/oder eine Lichtfarbe repräsentiert, die von einer Position im Umfeld des Fahrzeugs reflektiert wird, wobei die Position von zumindest einem Scheinwerfer des Fahrzeugs angestrahlt wird;
• – Vergleichen des Reflexionssignals mit einem aus einem Speicher ausgelesenen Wert und/oder einem Vergleichssignal, wobei der Wert eine vorbestimmte Lichtintensität und/oder eine vorbestimmte Lichtfarbe und/oder das Vergleichssignal eine Lichtintensität und/oder eine Lichtfarbe an einer zur Position benachbarten Vergleichsposition repräsentiert; und
• – Ausgeben eines Oberflächenzustandssignals, das die Oberflächenzustand der von dem Fahrzeug befahrenen und/oder zu befahrenden Fahrbahn repräsentiert, wenn das Reflexionssignal in einer vorbestimmten Beziehung zu dem aus dem Speicher ausgelesenen Wert und/oder zu dem Vergleichssignal steht.

The present invention provides a method for determining a surface condition of a roadway traveled or driven by a vehicle, the method comprising the following steps:

• - reading a reflection signal representing a light intensity and / or a light color, which is reflected from a position in the vicinity of the vehicle, wherein the position is illuminated by at least one headlight of the vehicle;
• Comparing the reflection signal with a value read from a memory and / or a comparison signal, the value representing a predetermined light intensity and / or a predetermined light color and / or the comparison signal representing a light intensity and / or a light color at a comparison position adjacent to the position; and
• Outputting a surface condition signal representing the surface condition of the road traveled and / or driven by the vehicle when the reflection signal is in a predetermined relationship to the value read from the memory and / or to the comparison signal.

• – eine Schnittstelle zum Einlesen eines Reflexionssignals, das eine Lichtintensität und/oder eine Lichtfarbe repräsentiert, die von einer Position im Umfeld des Fahrzeugs reflektiert wird, wobei die Position von zumindest einem Scheinwerfer des Fahrzeugs angestrahlt wird;
• – eine Einheit zum Vergleichen des Reflexionssignals mit einem aus einem Speicher ausgelesenen Wert und/oder einem Vergleichssignal, wobei der Wert eine vorbestimmte Lichtintensität und/oder eine vorbestimmte Lichtfarbe und/oder das Vergleichssignal eine Lichtintensität und/oder eine Lichtfarbe an einer zur Position benachbarten Vergleichsposition repräsentiert; und
• – eine Schnittstelle zum Ausgeben eines Oberflächenzustandssignals, das den Oberflächenzustand der von dem Fahrzeug befahrenen und/oder zu befahrenden Fahrbahn repräsentiert, wenn das Reflexionssignal in einer vorbestimmten Beziehung zu dem aus dem Speicher ausgelesenen Wert und/oder zu dem Vergleichssignal steht.

Furthermore, the present invention provides a device for determining a surface condition of a roadway traveled or driven by a vehicle, the device having the following features:

• An interface for reading in a reflection signal representing a light intensity and / or a light color which is reflected from a position in the vicinity of the vehicle, the position being illuminated by at least one headlight of the vehicle;
• A unit for comparing the reflection signal with a value read from a memory and / or a comparison signal, the value having a predetermined light intensity and / or a predetermined light color and / or the comparison signal a light intensity and / or a light color at a comparison position adjacent to the position represents; and
• An interface for outputting a surface condition signal representing the surface condition of the road traveled and / or driven by the vehicle when the reflection signal is in a predetermined relationship to the value read from the memory and / or the comparison signal.

The present invention thus provides a device which is designed to carry out or implement the steps of the method according to the invention in corresponding devices. Also by this embodiment of the invention in the form of a device, the object underlying the invention can be solved quickly and efficiently.

A computer program product with program code which can be stored on a machine-readable carrier such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out the method according to one of the embodiments described above if the program is installed on a computer or a device is also of advantage is performed.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control signals in dependence thereon. The device may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based configuration, the interfaces can be part of a so-called system ASIC, for example, which can be used for a variety of functions of the device includes. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

Under a road used by or driven by a vehicle is a lane or road to understand on which the vehicle has already traveled a distance or will cover a distance in the immediate future. A surface condition is understood to mean a physical property of the surface of the roadway that is relevant to the driving dynamics of the vehicle on the road. For example, the surface condition may be represented by moisture, wetness, icing of the roadway, a covering of the roadway with snow, grit or the like, so that when driving over the roadway with this surface condition, the vehicle has a different dynamics of movement than with a dry roadway. A reflection signal is understood to mean a signal (or its value) detected by an optical sensor, such as a camera, which represents an intensity of reflected light and / or a color of reflected light from a position in the vicinity of the vehicle. The position in the vicinity of the vehicle may be, for example, an area of the roadway on which the vehicle is driven or will drive. Alternatively or additionally, the position of the surroundings of the vehicle can also be an area next to the roadway, for example an area of a stand-off strip or a sand strip next to the roadway. This position or the area around the vehicle is illuminated by at least one headlight of the vehicle, this headlight of the vehicle may be, for example, one of the headlights of the vehicle or a specially designed to illuminate the position or area around the vehicle headlights , By a value that is read out from a memory, for example, a threshold value can be understood, which is used to determine whether the reflection signal has a light intensity that exceeds a predetermined threshold and / or has a light color, for example, within a spectral range or Color tolerance range is located in order to allow a conclusion on the surface condition of the road in the area of the position of the environment of the vehicle. A comparison position can be understood to mean a further area in the surroundings of the vehicle which differs from the position or the area in the surroundings of the vehicle which serves as the basis for the determination of the reflection signal. A surface condition signal may be understood as a signal containing information on a predetermined surface condition in the vicinity of the vehicle.

The present invention is based on the recognition that in modern vehicles often already an optical sensor for detecting the environment or the environment of the vehicle is present, which can be used for additional functionality of the detection of the surface condition of the roadway in the vicinity of the vehicle. In this case, it can be exploited that in certain scenarios, such as a rain-dampened roadway or a snow-covered roadway and an illumination of this roadway with a light from at least one headlight of the vehicle, a reflection behavior results, which differs from a reflection behavior in a dry road. For example, in a wet pavement scenario, a greater proportion of light is reflected off the roadway or a portion of the roadway than would occur on a dry roadway. The same applies to a scenario in which the road surface is covered with snow. If there are also markings on a roadway, for example, the reflection behavior of light in this area of the markings can be compared with a reflection behavior of light in the area of the roadway without markings, so that a conclusion on the surface condition of the roadway is possible. In this case, for example, by the mirror effect of the wet on the road, the contrast between a mark on the road and an area without marking will not be as strong as if the road was dry. Alternatively or additionally, it can be utilized that in a wet or snow-covered roadway certain spectral components are reflected more strongly than other spectral components of the light emitted by the headlight of the vehicle, so that an indication of the surface condition of the roadway is also possible.

The present invention offers the advantage of opening an additional benefit by already available technical facilities in modern vehicles. On the one hand, this makes it possible, on the one hand, to inexpensively verify a surface condition which has been detected by another system or, on the other hand, omit a special sensor or a special sensor function of this other system, if, for example, it should be very laborious or very unreliable.

It is favorable if, according to an embodiment of the present invention, in the step of outputting, a surface condition signal is output which represents a wet, wet or snow-covered roadway, if in step the comparison has been recognized that the reflection signal has a value which is greater than the value read from the memory and / or which corresponds to a value of the comparison signal within a tolerance range. Such an embodiment of the present invention offers the advantage of a technically very easy to determine surface condition of the road, which can then be used for another component of a driver assistance system.

According to another embodiment of the present invention, in the reading-in step, the reading-in of the reflection signal may be performed when no other vehicle or infrastructure is detected in a detection area of a reflection signal detection means. An infrastructure device can be understood, for example, as a structural measure such as a street lamp or a self-illuminating traffic sign, for example on a motorway. Such an embodiment of the present invention has the advantage that disturbances in the detection of the surface condition by light, which was not emitted by the relevant headlight of the vehicle, can be largely avoided.

Furthermore, according to a further embodiment of the present invention, in the step of reading in, the reading of the reflection signal can take place when the brightness in an environment of the vehicle is lower than a predetermined brightness threshold value. Such an embodiment of the present invention has the advantage that the surface condition of the roadway is detected, in particular in the dark or at night, so that a disturbance by light from others in sources other than the relevant headlight of the vehicle can be largely avoided.

It is furthermore particularly advantageous if, furthermore, a step of providing the reflection signal is provided, in which averaging of a plurality of detected brightness values takes place at different positions in the surroundings of the vehicle to form the reflection signal and / or in which the reflection signal is used using at least one camera a rear area of the vehicle is provided and / or in which the reflection signal is provided using a camera that is associated with a parking assistant of the vehicle. Such an embodiment of the present invention, for example, offers the advantage of a particularly robust provision of the reflection signal when the reflection signal is determined using averaging of a plurality of brightness values. Faults or errors in the detection of a single brightness value are then no longer significant. Alternatively or additionally, technical equipment of the vehicle can be used, which are usually present in modern vehicles, but are usually not used to determine a surface condition. In this way, an additional benefit of already available components of a vehicle can be achieved.

• – die Schritte wie sie in einem der vorstehend vorgestellten Verfahren ausgeführt werden; und
• – Verändern der Ausstrahlung von Licht aus einem Scheinwerfer des Fahrzeugs in Abhängigkeit von dem Oberflächenzustandssignal, um die Anpassung der Ausstrahlung von Licht aus dem Scheinwerfer des Fahrzeugs oder einem weiteren Scheinwerfer des Fahrzeugs vorzunehmen.

It is particularly advantageous if the recognized surface condition of the roadway is also used, for example, to avoid blinding the driver of his own vehicle or dazzling other road users. In this case, for example, a light emission by the headlight or another headlight of the vehicle can be adjusted in such a way that the reflection behavior of the roadway that is changed by the recognized surface state is also taken into account. A favorable embodiment of the present invention is therefore a method for adapting a radiation of light from a headlight of the vehicle, the method comprising the following steps:

• The steps carried out in one of the methods presented above; and
• - Changing the emission of light from a headlight of the vehicle in response to the surface condition signal to make the adjustment of the radiation of light from the headlight of the vehicle or another headlight of the vehicle.

The invention will now be described by way of example with reference to the accompanying drawings. Show it:

1 a block diagram of a vehicle in which an embodiment of the present invention is used;

2 a flowchart of an embodiment of the present invention; and

3 a block diagram of a vehicle, in which at least one embodiment of the present invention is used.

In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similarly acting, wherein a repeated description of these elements is omitted.

1 shows a block diagram of a vehicle 100 in which an embodiment of the present invention is used. This includes the vehicle 100 a camera 110 , by means of which a detection area 115 an environment 120 of vehicle 100 is observed. A roadway 125 that from the vehicle 100 during a movement of the vehicle 100 in a direction of travel 127 is in the future, is within the scope 115 the camera 110 , Furthermore, the vehicle includes 100 at least one headlight 130 , in the present example 1 are in particular two headlights 130 as the headlight of the vehicle 100 represented by the light in an illumination area 135 in the environment 120 the vehicle is broadcast. This is done by an area 140 the roadway 125 a reflection of light from the headlamp 130 to the camera 110 of which one or more parameters are evaluated in a manner described in more detail below. A reflection behavior of the headlight 130 output light in the area 140 (which can also be referred to as a position) is in this case of a surface condition of the roadway 125 dependent. For example, a wet roadway reflects in the area 140 a higher amount of light from the headlight 130 output light to the camera 110 back than this on a dry lane 125 would be done. Even on a snow-covered road 125 will be in the area 140 much more light from the headlamp 130 to the camera 110 reflected than this on a dry road surface 125 would be done. The camera 110 therefore gives a reflection signal 150 out, which via an interface 157 from a unit to compare 160 is read. The reflection signal 150 For example, it represents a light intensity that depends on the position 140 in the environment 120 of the vehicle 100 which is reflected by at least one headlight 130 of the vehicle 100 is illuminated.

In the unit for comparison 160 then, for example, the reflection signal 150 , in particular a value of the reflection signal 150 with an example from a memory 165 read value 167 compared. This value 167 For example, it may form a threshold that indicates that the area or position 140 the roadway 125 must be wet or damp to get a light intensity of light from the headlight 130 Reflect as seen from the camera 110 was received and in the reflection signal 150 was coded. The result of this comparison, in the unit 160 was performed for comparing, is subsequently in an interface 170 in which the surface condition signal 175 determined and to other vehicle components, for example, a lighting control unit 180 is issued. In this way, the lighting control unit is located 180 which transmit the light through the headlights 130 controls or influences information about the surface condition of the roadway 125 before that when driving the headlights 130 can be used for light emission. For example, an angle of light emission by the headlights 130 be changed if at least one other, in particular oncoming vehicle (for example, by the camera 110 ) is detected to dazzle a driver of this vehicle by a reflection of light from the headlamp 130 on a wet or snow covered roadway 125 to avoid.

Alternatively or additionally, also the reflection signal 150 represent a light color or a color spectrum, where the value 167 coming out of the store 165 is read out, also representing a color or a color spectrum. This can be exploited that certain states of the surface of a roadway 125 different reflection characteristics of different spectral components of the headlight 130 have emitted light. In the unit 160 For comparison, it can then be determined to what degree a match between the light color or the color spectrum from the reflection signal 150 and the color or the color spectrum from the value 167 consists. If a high degree of match is found (for example, a match of the color or color spectrum encoded in the reflection signal with the color encoded in the value from memory or the color spectrum encoded in the value from memory), it can be concluded that in the area or the position 140 a surface condition of the roadway 120 which is also the value 167 is assigned in the memory.

Alternatively or additionally, a comparison signal can also be used 155 from the camera 110 to the unit 160 provided for comparison, wherein the comparison signal 155 according to the reflection signal 150 a light intensity and / or a light color or a light spectrum from one to the area 140 adjacent comparison area 145 represents. In the unit 160 to compare will replace the value 167 the comparison signal 155 used. Such an approach is based on the knowledge that, for example, a difference between reflected light intensities at different positions in the environment 120 of the vehicle 100 , especially on a roadway 125 from a (uniform) surface condition of the roadway 125 is dependent.

For example, in a wet or wet pavement by light reflection significantly more light from dark areas of this roadway (that is, for example, areas without lane markings) are reflected, as in a dry lane 125 is possible. In this case, for example, in the unit 160 be recognized for comparing that the light intensity corresponding to the reflection signal 150 around less than a certain tolerance range from the light intensity corresponding to the comparison signal 155 makes a difference, which then results in a wet or damp road surface 125 can be closed.

To ensure that the evaluation of the area 140 or from the wider area 145 Reflected light is possible without interference, an evaluation of this reflected light can be limited to periods in which darkness or night prevails. Such a period can be recognized, for example, by the fact that the camera 110 in an environment 120 of the vehicle 100 a (background) brightness is detected that is below a certain brightness threshold. Alternatively or additionally, an evaluation of the surface condition of the roadway 125 then take place, if no further light-emitting object in the detection area 115 the camera 110 is recognized. Such a light-emitting object can be, for example, a vehicle of oncoming traffic, a rear light of the vehicle and / or a street lamp as an infrastructure measure on the edge of the road 125 be. In this way, even in the dark using the camera usually already installed as standard in modern vehicles 110 a detection of the surface condition of the roadway 125 done without resorting to sensor signals such as an ABS or ESP system.

2 shows a flowchart of an embodiment of the present invention as a method 200 for determining a surface condition of a road used by or driven on a vehicle. The procedure 200 includes a step of reading 210 a reflection signal representing a light intensity and / or a light color reflected from a position around the vehicle, the position being illuminated by at least one headlight of the vehicle. Furthermore, the method comprises a step of comparing 220 the reflection signal having a value read from a memory and / or a comparison signal, the value representing a predetermined light intensity and / or a predetermined light color and the comparison signal representing a light intensity and / or a light color at a comparison position adjacent to the position. Finally, the process includes 200 a step of spending 230 a surface condition signal representing the surface condition of the roadway traveled and / or driven by the vehicle when the reflection signal is in a predetermined relationship to the value read from the memory and / or to the comparison signal.

3 shows a block diagram of another vehicle 300 in which at least one embodiment of the present invention is used. It is from the 3 you can see that not just a camera 100 as they are in the 1 is shown, can be used. It is alternatively or additionally, for example, a camera 310 to implement the approach presented here, in a page mirror 320 of the vehicle is arranged. Additionally or alternatively, instead of in the 1 shown headlights 130 used a light source, which is also in the side mirror 320 is arranged. The approach presented here also works if instead of looking in the direction of travel camera 110 (or directly down the road 125 looking camera in a side mirror) a rear view camera 330 used, for example, associated with a parking assistant. It is in the in 3 shown alternative options for the embodiment of the invention is not mandatory that the headlights 130 according to the 1 provide the light that is reflected to the respective camera.

In summary, it should be noted in connection with the approach presented here according to an exemplary embodiment that the coefficient of friction, which is often directly related to the surface condition of the road, can be measured with the aid of a camera which measures the reflection behavior of the road. At night, the determination can be made by measuring the reflection of light from his or her own headlamps. For example, the areas in the image that are illuminated by the headlamps are analyzed. If there are particularly bright areas in the picture, so you can make the assumption that it is a wet road. Alternatively or additionally, further ratios of the pixel values within the expected headlight areas in the image can be evaluated. For example, the mean value can be used for the detection of snow-covered road. To avoid the influence of other vehicles or infrastructure lights, such a measurement can only be performed if none of these objects are visible in the image.

An important aspect of the present invention is that an approach or system is proposed, which compares the existing light distribution with an expected light distribution and then allows conclusions on the road events. When it rains or snow can still be closed on the current road surface, if it does not rain or snow directly.

The advantage of the system is that other driver assistance systems use these To be able to use information about the surface condition of the road to adapt their parameterization accordingly. Thus, the light distribution can be selected depending on the road surface to avoid glare from the strong reflection of the road for your own vehicle or for other vehicles.

In addition to the use of a forward-looking camera, multi-camera system, as used in parking systems, can be very well used to solve the problem, since such cameras have a direct view of the road, they can change the spectral examine the light source installed on the vehicle and thus draw conclusions about the condition of the road.

The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined together or in relation to individual features. Also, an embodiment can be supplemented by features of another embodiment.

Furthermore, method steps according to the invention can be repeated as well as carried out in a sequence other than that described.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010033007 A1 [0002]

Claims (8)

Procedure ( 200 ) for determining a surface condition of a vehicle ( 100 . 300 ) traveled or to be driven roadway ( 125 ), the process ( 200 ) comprises the following steps: - reading in ( 210 ) of a reflection signal ( 150 ), which represents a light intensity and / or a light color, which is from a position ( 140 ) in the environment ( 120 ) of the vehicle ( 100 . 300 ), the position ( 140 ) of at least one headlight ( 130 ) of the vehicle ( 100 . 300 ) is irradiated; - To compare ( 220 ) of the reflection signal ( 150 ) with a value read from a memory ( 167 ) and / or a comparison signal ( 155 ), where the value ( 167 ) a predetermined light intensity and / or a predetermined light color and / or the comparison signal ( 155 ) a light intensity and / or a light color at one of the position ( 140 ) adjacent comparison position ( 145 represents; and - spend ( 230 ) a surface condition signal ( 175 ), which determines the surface condition of the vehicle ( 100 . 300 ) traveled and / or to be driven lane ( 125 ), when the reflection signal ( 150 ) in a predetermined relation to the value read from the memory ( 167 ) and / or to the comparison signal ( 155 ) stands. Procedure ( 200 ) according to claim 1, characterized in that in the step of outputting ( 230 ) a surface condition signal is output which indicates a wet, wet or snow-covered roadway ( 125 ), when in the step of comparing ( 220 ) was detected that the reflection signal ( 150 ) greater than the value read from the memory ( 167 ) and / or greater than the comparison signal ( 155 ). Procedure ( 200 ) according to one of the preceding claims, characterized in that in the step of reading ( 210 ) the reading of the reflection signal ( 150 ) takes place when no other vehicle or infrastructure in a coverage area ( 115 ) a detection device ( 110 ) for providing the reflection signal ( 150 ) is detected. Procedure ( 200 ) according to one of the preceding claims, characterized in that in the step of reading ( 210 ) the reading of the reflection signal ( 150 ) then takes place when the brightness in an environment ( 120 ) of the vehicle ( 100 ) is lower than a brightness threshold. Procedure ( 200 ) according to one of the preceding claims, characterized in that further comprises a step of providing the reflection signal ( 150 ) in which averaging of a plurality of detected brightness values at different positions ( 140 . 145 ) in the environment ( 120 ) of the vehicle ( 100 ) for forming the reflection signal ( 150 ) and / or in which the reflection signal ( 150 ) using at least one camera ( 310 ) in a side mirror ( 320 ) of the vehicle ( 300 ) and / or in which the reflection signal ( 150 ) using a camera ( 330 ), which is associated with a parking assistant of the vehicle, in particular, in a rear area of the vehicle ( 100 ) is arranged. Method for adapting a radiation of light from a headlight ( 100 ) of the vehicle ( 100 . 300 ), the method comprising the following steps: - the steps ( 210 . 220 . 230 ) according to one of the preceding claims; and - changing the emission of light from a headlight ( 130 ) of the vehicle ( 100 . 300 ) in dependence on the surface condition signal ( 175 ) to adjust the emission of light from the headlamp ( 130 ) of the vehicle ( 100 . 300 ). Contraption ( 157 . 160 . 170 ) for determining a surface condition of a vehicle ( 100 . 300 ) traveled or to be driven roadway ( 125 ), the device ( 157 . 160 . 170 ) has the following features: an interface ( 157 ) for reading a reflection signal ( 150 ), which represents a light intensity or a light color coming from a position ( 140 ) in the environment ( 120 ) of the vehicle ( 100 . 300 ), the position ( 140 ) of at least one headlight ( 130 ) of the vehicle ( 100 . 300 ) is irradiated; - one unity ( 160 ) for comparing the reflection signal ( 150 ) with one from a memory ( 165 ) read value ( 167 ) or a comparison signal ( 155 ), where the value ( 167 ) a predetermined light intensity and / or a predetermined light color and / or the comparison signal ( 155 ) a light intensity and / or a light color at one of the position ( 140 ) adjacent comparison position ( 145 represents; and - an interface ( 170 ) for outputting a surface condition signal ( 175 ), which determines the surface condition of the vehicle ( 100 . 300 ) traveled and / or to be driven lane ( 125 ), when the reflection signal ( 150 ) in a predetermined relationship to that from the memory ( 165 ) read value ( 167 ) or to the comparison signal. Computer program product with program code for carrying out the method ( 200 ) to one of claims 1 to 6, when the program is stored on a device ( 157 . 160 . 170 ) is performed.

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