Method for operating at least one surroundings detection sensor of a vehicle

Abstract

According to the present invention, a vehicle (1) is positioned in a digital map, objects (O) are stored in the digital map in a manner associated with geography, an object (O) farthest from the environment detection sensor (2) is identified from a group of objects (O) currently detected by an environment detection sensor (2) and stored in the digital map in a manner associated with geography, and a current sensor effective range of the environment detection sensor (2) is determined based on the distance between the environment detection sensor (2) and the object (O).

Description

Technical Field

[0001] The invention relates to a method for operating at least one surroundings detection sensor of a vehicle. Background Art

[0002] In general, methods for operating surroundings detection sensors of a vehicle are known from the prior art.

[0003] DE 102018127059.3 describes a method for checking at least one environment detection sensor of a vehicle. In the method, the vehicle is located in a digital map and stored features of stationary objects in the vehicle environment that are expected to be detected by the environment detection sensor are identified in the digital map. The environment of the vehicle is detected with the aid of the environment detection sensor. If the environment detection sensor does not detect the features expected to be detected or if the features actually detected by the environment detection sensor deviate greatly from the features expected to be detected, degradation of the environment detection sensor is inferred. Summary of the invention

[0004] The object of the present invention is to specify a method for operating at least one surroundings detection sensor of a vehicle which is improved compared to the prior art.

[0005] According to the invention, the object is achieved by a method according to the invention for operating at least one environment detection sensor of a vehicle. According to the method according to the invention, the vehicle is located in a digital map, objects are stored in the digital map in a geographically linked manner, and the object farthest from the environment detection sensor is identified from a group of objects currently detected by the environment detection sensor and stored in the digital map in a geographically linked manner, and the current sensor range of the environment detection sensor is determined based on the distance between the environment detection sensor and the object, and object information respectively associated with the objects is stored in the digital map, the object information of the respective object indicating at least for the environment detection sensor for a plurality of different detection conditions a respective distance from the environment detection sensor to the object, from which the environment detection sensor can detect the object, wherein the object information of the object farthest from the environment detection sensor is retrieved from the digital map and a detection condition is determined based thereon, the distance assigned to the environment detection sensor being most relevant to the determined current sensor range of the environment detection sensor. The detection conditions determined by a plurality of environment detection sensors of the vehicle are compared with one another.

[0006] In a method according to the invention for operating at least one environment detection sensor of a vehicle, in particular a road vehicle, the vehicle is positioned in a digital map, objects, in particular stationary objects, are stored in the digital map in a geographically linked manner, and from a group of these objects stored in the digital map in a geographically linked manner and currently detected by the environment detection sensor, an object farthest from the environment detection sensor is identified and a current sensor range of the environment detection sensor is determined based on the distance between the environment detection sensor and the object.

[0007] The environment detection sensor is, for example, a lidar sensor, a radar sensor, an ultrasonic sensor and / or an optical sensor. The optical sensor is in particular an image detection sensor, in particular a video sensor, for example a camera, such as a stereo camera or a monocular camera. The lidar sensor can also be regarded as an optical sensor.

[0008] The current sensor range of the environment detection sensor can be determined at least indirectly by means of the method according to the invention. The actual sensor range can be greater than, but not less than, the current sensor range determined by means of the method according to the invention, because the current sensor range is related to, and in particular corresponds to, the distance of the furthest object that can still be detected by the environment detection sensor. The actual sensor range can be greater if there are no objects farther away that can be detected by the environment detection sensor within the actual sensor range.

[0009] With the aid of the method, for example, the current sensor range which is reduced due to atmospheric influences and the resulting functional limitations can be determined, in particular in a rapid manner and without the need for additional sensors and other services. Such atmospheric influences include, for example, rain, fog, snow and / or resulting artifacts on the road surface, such as moisture, hoarfrost and / or snowflakes. As a result, for example, a corresponding system response of at least one vehicle system of the vehicle that uses the environmental detection sensor or a plurality of such vehicle systems can be initiated, thereby achieving improved safety. The method is suitable, for example, for automated and / or self-driving vehicles that use one or more such environmental detection sensors to detect the vehicle's environment for driving operations.

[0010] For example, the distance from the environment detection sensor to the identified object farthest from the environment detection sensor is determined as the current sensor effective range of the environment detection sensor. This is particularly applicable to a detection range that extends around the environment detection sensor in a circular or spherical shape or at least in a circular segment or spherical segment shape, so that the boundary of the detection range, that is, the current sensor effective range of the environment detection sensor, is the same for all detection directions within the detection range.

[0011] Especially if the environment detection sensor has a detection range of different shapes, for example, configured as an ellipse or ellipsoid or at least configured as a detection range of a section of the ellipse or ellipsoid, it is advantageous to assume that the object farthest from the environment detection sensor identified is located on the boundary of the detection range, so that the current detection range of the environment detection sensor, especially the boundary of the current detection range, can be determined for all angular positions, i.e., for all detection directions by the distance to the object (especially in combination with the determined angular position of the object relative to the environment detection sensor) and by the known shape of the detection range, so that the current sensor effective range of the environment detection sensor can be determined for all detection directions in the detection range. Advantageously, the sensor effective range includes an effective range description for each angular position, i.e., for each detection direction. Therefore, the determined current sensor effective range corresponds to / equals the current distance from the boundary of the current detection range of the environment detection sensor to the environment detection sensor. This scheme of determining the current sensor effective range can certainly also be used for other detection range shapes, especially for detection ranges that are also circular or spherical or at least circular segment or spherical segment extending around the environment detection sensor.

[0012] According to the invention, object information respectively associated with the objects is stored in a digital map, the object information of the respective object giving at least for the environment detection sensor for a plurality of different detection conditions a respective distance from the environment detection sensor to the object, from which the environment detection sensor can detect the object, the object information of the object currently detected by the environment detection sensor and farthest from the environment detection sensor is called from the digital map and a detection condition is determined based on this, the distance assigned to this detection condition being most relevant to the current sensor effective range determined for the environment detection sensor, i.e., in particular, having the smallest deviation from the current sensor effective range determined for the environment detection sensor. Thus, not only the current sensor effective range can be determined, but also the cause of this current sensor effective range can be determined, in particular if the current sensor effective range is limited compared to the sensor effective range under the best detection conditions. In particular, atmospheric influences can be determined as the cause of the corresponding, in particular limited, current sensor effective range. Based on this, for example, the probability of a change in the friction coefficient characteristics of the road surface (for example, due to moisture, snow and / or ice) can be determined. Thus, a corresponding system response of at least one or more vehicle systems can be subsequently performed, for example, reducing the vehicle speed and / or increasing the safety distance to another traffic participant traveling ahead.

[0013] Advantageously, the object information of the corresponding object gives, for a plurality of different types of environmental detection sensors (such as lidar sensors, radar sensors, ultrasonic sensors and / or optical sensors, in particular image detection sensors, in particular cameras, such as stereo cameras and / or monocular cameras), a corresponding distance from the environmental detection sensor to the object for a plurality of different detection conditions, from which the environmental detection sensor of the corresponding type of environmental detection sensor can detect the object. Thus, the described processing method can be performed for different types of environmental detection sensors of a vehicle and thus, for example, the detection conditions can be determined respectively by means of a plurality of environmental detection sensors of a vehicle.

[0014] In one embodiment of the method, the object information of the corresponding object is determined by detecting the corresponding object with the help of the environment detection sensor and / or with the help of the same type of environment detection sensors and fusing and evaluating with the corresponding existing detection conditions, especially weather conditions, especially on a server outside the vehicle, which at least for the environment detection sensor, for a plurality of different detection conditions, gives the corresponding distance from the environment detection sensor to the object, from which the environment detection sensor can detect the object. As a result, the information can be learned with the help of the environment detection sensors of the vehicle, especially the same type of environment detection sensors of a plurality of vehicles, thereby avoiding the additional cost of separately creating the information by other means.

[0015] In one embodiment of the method, detection conditions determined by a plurality of environment detection sensors of the vehicle and / or detection conditions determined based on a plurality of objects are compared with one another. This makes it possible, for example, to ensure that a determined reduction in the effective range of a sensor is not based on hardware degradation of the corresponding environment detection sensor, but is actually based on atmospheric influences, in particular if the same detection conditions are determined by a plurality of environment detection sensors.

[0016] Instead of the above-mentioned solution according to the invention and / or one or more of the above-mentioned embodiments or in addition thereto, it can be provided, for example, that the current effective road surface detection range of the environmental detection sensor is determined by means of an environmental detection sensor constructed as an optical sensor, i.e., an environmental detection sensor constructed as a lidar sensor or an image detection sensor, and the current road surface conditions are determined based on the road surface conditions stored in a table and the assigned effective road surface detection range. Therefore, this can be a component of the above-mentioned method for operating at least one environmental detection sensor of a vehicle or, for example, can also be performed as an alternative to it, i.e., in an alternative method for operating at least one environmental detection sensor of a vehicle. The optical sensor, in particular the image detection sensor, is, for example, a camera, such as a stereo camera or a monocular camera, in particular a video sensor. As an alternative, as described above, the optical sensor can also be, for example, a lidar sensor.

[0017] If there is water on the road surface, that is, if the road surface is covered with water, the effective road surface detection range will be reduced compared to a dry road surface, because the water coverage on the road surface, for example, reduces the backscatter intensity of the laser radar signal of the environment detection sensor configured as a laser radar sensor. Even if an environment detection sensor configured as an image detection sensor is used, if there is water on the road surface, that is, when the road surface is covered with water, especially when there is a water film, especially in combination with solar radiation, the effective road surface detection range will be reduced compared to a dry road surface, because the water coverage on the road surface, especially in combination with solar radiation, can cause reflections, which "blind" the image detection sensor, especially the video sensor.

[0018] The type of change in the road condition that is present can thus be inferred. For example, a corresponding system response of at least one vehicle system or a plurality of such vehicle systems of the vehicle can thereby also be initiated, so that improved safety can be achieved, for example, by adapting the vehicle's speed and / or the distance to another road user traveling ahead to the determined road condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The accompanying drawings are as follows:

[0020] Figure 1 A vehicle with at least one surroundings detection sensor is schematically shown on a lane. DETAILED DESCRIPTION

[0021] Figure 1 An exemplary situation, in particular a traffic situation, is schematically shown, which has a vehicle 1, in particular a road vehicle, on a lane F, which has at least one environment detection sensor 2. The environment detection sensor 2 is, for example, a lidar sensor, a radar sensor, an ultrasonic sensor and / or an optical sensor, in particular an image detection sensor, for example a camera such as a stereo or monocular camera, in particular a video sensor. A lidar sensor can also be regarded as an optical sensor. Advantageously, the vehicle 1 has a plurality of different types of environment detection sensors 2.

[0022] The environment of the vehicle 1 is detected by means of the at least one or corresponding environment detection sensor 2 of the vehicle 1. This is used, for example, to determine the position of the vehicle 1 based on, in particular, stationary objects O in the environment of the vehicle 1 and / or to operate at least one vehicle system or a plurality of vehicle systems, in particular vehicle systems that assist the vehicle driver when driving the vehicle 1 and / or vehicle systems that perform automation, in particular partially or fully automated or autonomous driving operation of the vehicle 1. The vehicle 1 is therefore, for example, an automated or autonomous driving vehicle 1.

[0023] In the following Figure 1In a method for operating such an environment detection sensor 2, which is described in more detail, the vehicle 1 is located in a digital map, in which in particular stationary objects O are stored in a geographically linked manner, which objects can be detected or should be detected by means of the environment detection sensor 2. From a group of these objects O which are stored in a geographically linked manner in the digital map and are currently detected by the environment detection sensor 2, the object O which is farthest from the environment detection sensor 2 is identified and the current sensor range of the environment detection sensor 2 is determined based on the distance between the environment detection sensor 2 and the object O.

[0024] For example, the distance between the environment detection sensor 2 and the object O is determined as the current sensor effective range of the environment detection sensor 2. This is particularly applicable to a detection range that extends around the environment detection sensor 2 in a circular or spherical shape or at least in a circular segment or spherical segment shape, so that the boundary of the detection range, that is, the current sensor effective range of the environment detection sensor 2, is the same for all detection directions within the detection range.

[0025] In particular, if the surroundings detection sensor has a detection range of a different shape, for example, as an ellipse or ellipsoid or at least as a detection range of a segment thereof, such as Figure 1 As shown, it is advantageous to assume that the object O that is the farthest from the environment detection sensor 2 is located on the boundary of the detection range, so that the current detection range of the environment detection sensor 2, especially the boundary of the current detection range, can be determined for all angular positions, that is, for all detection directions by the distance to the object O (especially in combination with the determined angular position of the object O relative to the environment detection sensor 2) and the known shape of the detection range, so that the current sensor effective range of the environment detection sensor 2 can be determined for all detection directions in the detection range. Advantageously, the sensor effective range includes a range description for each angular position, that is, for each detection direction. Therefore, the determined current sensor effective range corresponds to the current distance from the boundary of the current detection range of the environment detection sensor 2 to the environment detection sensor 2. This scheme for determining the current sensor effective range can certainly also be used for other detection range shapes, especially for detection ranges that are circular or spherical or at least circular arc or spherical segment extending around the environment detection sensor 2.

[0026] Such an object O, which is in particular stationary, is, for example, a guardrail, a building and / or, as in the example shown here, a pole, in particular a guide post.

[0027] Therefore, the method can determine the current sensor effective range of the environment detection sensor 2 and therefore especially at least one sensor technology of an automated or self-driving vehicle in a simple and fast manner and in particular without any additional equipment costs. The environment detection sensor 2, in particular the sensor technology of the corresponding environment detection sensor 2, may be functionally limited, for example, due to atmospheric influences. This is identified with the help of the method described in this article, whereby a corresponding system response of at least one vehicle system or multiple vehicle systems can be achieved, for example. For example, in the case where the current determined sensor effective range is reduced compared to the sensor effective range under optimal detection conditions, the speed of the vehicle 1 can be reduced and / or the distance to another traffic participant traveling in front can be increased. Atmospheric influences that can lead to a reduction in the sensor effective range are, for example, rain, fog, snow and / or artifacts on the road surface caused thereby, such as moisture, hoarfrost and / or snowflakes.

[0028] Until now, atmospheric influences have been reported, for example, by a remote control service, in particular in the form of weather information, and can therefore be taken into account accordingly. However, such weather information has a high degree of uncertainty with respect to the actual situation in the correspondingly very limited local environment of the vehicle 1. With the method described here, such processing methods are no longer necessary, because the current sensor range, which is limited, in particular due to atmospheric influences, is determined by means of the environment detection sensor 2 itself.

[0029] Advantageously, the method can also be used to infer the atmospheric causes of a possibly limited sensor range. For example, the probability of a change in the road surface friction coefficient conditions can be determined, and the driving behavior of the vehicle 1 can then be adjusted accordingly, for example by reducing the speed and / or increasing the distance to other road users driving ahead, thereby increasing safety.

[0030] In order to achieve this, it is advantageous to store object information respectively related to the object O in a digital map, the object information of the corresponding object O giving the corresponding distance from the environment detection sensor 2 to the object O for the environment detection sensor 2 and therefore also for the same type of environment detection sensors 2 for a plurality of different detection conditions, from which the environment detection sensor 2 can detect the object O. Then, the object information of the object O currently detected by the environment detection sensor 2 and farthest from the environment detection sensor 2 is called from the digital map and a detection condition is determined based on it, the distance assigned to the environment detection sensor 2 being most relevant to the determined current sensor effective range of the environment detection sensor 2. Therefore, it is advantageous to determine such a detection condition, the distance assigned from the environment detection sensor 2 to the object O, i.e. to the object O currently detected by the environment detection sensor 2 and farthest from the environment detection sensor 2, being closest to the determined current sensor effective range.

[0031] In accordance with Figure 1 In the example of FIG. 1 , an object O stored in a geographically associated manner in the digital map is, for example, constructed as a rod, such as a guide post. A large sensor range SR1, such as the maximum sensor range under good, especially optimal atmospheric conditions, especially weather conditions, and a smaller current sensor range SR2 generated due to atmospheric influences are also shown. It can be seen that under good, especially optimal atmospheric conditions, especially weather conditions, objects O that are far away from the vehicle 1, i.e., the object O farthest from the vehicle 1 shown here, can be detected with the help of the surrounding detection sensor 2 based on the large sensor range SR1 generated thereby. Under the smaller current sensor range SR2, these objects O that are far away from the vehicle 1, i.e., the object O farthest from the vehicle 1 shown here, can no longer be detected by the surrounding detection sensor 2, but only those objects O that are at a short distance from the surrounding detection sensor 2 and are therefore located within the smaller current sensor range SR2 can be detected. As described above, the information "how far away from the vehicle 1 the environmental detection sensor 2 can detect the corresponding object O under the corresponding detection conditions" is stored in the digital map, so that the corresponding detection conditions can be inferred based on the determined sensor effective range and the object O currently detected by the environmental detection sensor 2 that is farthest from the environmental detection sensor 2, and thus the corresponding atmospheric reasons for the smaller current sensor effective range SR2 can be inferred.

[0032] Advantageously, the object information of the corresponding object O provides the corresponding distances from the environment detection sensor 2 to the object O for or for different types of environment detection sensors 2 (such as lidar sensors, radar sensors, ultrasonic sensors and / or optical sensors, in particular image detection sensors, such as cameras, such as stereo cameras and / or monocular cameras, in particular video sensors) for a plurality of different detection conditions, from which the environment detection sensor 2 of the corresponding environment detection sensor type can detect the object O. In other words, a plurality of different detection conditions and the assigned distances to the corresponding object O are stored for each type of environment detection sensor 2, from which the object O can be detected under the corresponding detection conditions by means of the environment detection sensor 2 of the corresponding type. As a result, the described processing method can be performed for different types of environment detection sensors 2 of the vehicle 1 and thus, for example, the detection conditions can be determined respectively by means of a plurality of environment detection sensors 2 of the vehicle 1.

[0033] Thus, for example, detection conditions determined by a plurality of environmental detection sensors 2 of the vehicle 1, i.e., detection conditions determined respectively by means of a plurality of environmental detection sensors 2, can be compared with one another. In this way, it can be ensured, for example, that a determined reduction in the effective range of the sensor is not based on a hardware degradation of the corresponding environmental detection sensor 2, but is actually based on atmospheric influences, in particular if the same detection conditions are determined by means of a plurality of environmental detection sensors 2. Alternatively or additionally, the detection conditions determined by means of the same environmental detection sensor 2 can also be compared with one another based on a plurality of objects O in order to exclude that a determined reduction in the effective range of the sensor is based on a hardware degradation of the environmental detection sensor 2.

[0034] For example, by fusing and evaluating these objects O with the additional detection conditions that exist respectively, especially in the form of weather information, the effective detection range of the object O can be learned from each position or at least from multiple positions. Advantageously, this is performed on a vehicle-external server, also referred to as the back end. That is, the object information of the corresponding object O is determined by detecting the corresponding object O with the help of the environment detection sensor 2 and / or with the help of the same type of environment detection sensor 2 and fusing and evaluating with the corresponding existing detection conditions, especially weather conditions, especially on the vehicle-external server, which gives the corresponding distance from the environment detection sensor 2 to the object O for the or the corresponding environment detection sensor 2 for multiple different detection conditions, from which the environment detection sensor 2 can detect the object O. As a result, this information can be learned with the help of the environment detection sensor 2 of the vehicle 1, especially with the help of the same type of environment detection sensors 2 of multiple vehicles 1, thereby avoiding the additional cost of creating this information separately by other means.

[0035] Instead of the above processing method or advantageously in addition thereto, it can be provided, for example, that the current effective road surface detection range of the environment detection sensor 2 is determined by means of the environment detection sensor 2 configured as an optical sensor, that is, in particular, by means of the environment detection sensor 2 configured as a lidar sensor or by means of the environment detection sensor 2 configured as an image detection sensor, in particular, a video sensor, such as a camera, such as a stereo camera or a monocular camera, and the current road surface condition is determined based on the road surface condition and the assigned road surface detection effective range stored in a table, for example. In the case where the environment detection sensor 2 is configured as a lidar sensor, the current road surface detection effective range is determined in particular by the corresponding propagation time of the backscattered signal of the lidar sensor.

[0036] In accordance with Figure 1 In the example shown, the road surface is detected by means of an environment detection sensor 2 constructed as a lidar sensor, for example, by means of a dedicated lidar system. When the road surface is dry, for example, up to Figure 1As the road surface deteriorates, especially due to increased water coverage, the backscatter intensity of the lidar sensor signal decreases, so that the road surface can only be detected at a smaller distance - in Figure 1 1 is shown by the second line L2 which is closer to the vehicle 1. Based on the reduction of the road surface range, the corresponding type of road surface change can be inferred by the road surface conditions stored in a table and the assigned road surface detection effective range. As a result, for example, corresponding system responses of at least one vehicle system or a plurality of such vehicle systems of the vehicle 1 can also be initiated, so that improved safety can be achieved, for example, by adapting the speed of the vehicle 1 and / or the distance to another road participant traveling ahead to the determined road surface conditions.

[0037] As already mentioned, instead of configuring the environment detection sensor 2 as a lidar sensor, the environment detection sensor 2 can also be configured as another optical sensor, in particular an image detection sensor, in particular a video sensor, such as a camera, such as a stereo camera or a monocular camera. With the aid of this optical sensor, the road surface can be detected. When the road surface is dry, for example, it can be detected until Figure 1 Due to deteriorating road conditions, in particular due to increasing water coverage, in particular in combination with solar radiation and the resulting reflections, which would reflect light to the optical sensor and thus only detect the road surface at a smaller distance, Figure 1 1 is shown by the second line L2 which is closer to the vehicle 1. Here, too, the corresponding type of road surface change can be inferred based on the reduction of the road surface range, for example, by the road surface conditions stored in a table and the assigned road surface detection effective range. As a result, for example, corresponding system responses of at least one vehicle system or a plurality of such vehicle systems of the vehicle 1 can also be initiated, so that, for example, improved safety can be achieved by adapting the speed of the vehicle 1 and / or the distance to another road participant traveling ahead to the determined road surface conditions.

[0038] Reference numerals list

[0039] 1 Vehicle

[0040] 2 Environmental Detection Sensors

[0041] F Lane

[0042] L1 first line

[0043] L2 Second Line

[0044] OObject

[0045] SR1 Large sensor effective range

[0046] SR2 has a smaller current sensor range

Claims

1. A method for operating at least one environment detection sensor (2) of a vehicle (1), characterized in that: The vehicle (1) is positioned in a digital map, an object (O) is stored in the digital map in a geographically associated manner, and an object (O) farthest from the environment detection sensor (2) is identified from a group of objects (O) stored in the digital map in a geographically associated manner and currently detected by the environment detection sensor (2), and a current sensor effective range of the environment detection sensor (2) is determined based on the distance between the environment detection sensor (2) and the object (O), and Object information respectively related to the object (O) is stored in a digital map, the object information of the corresponding object (O) at least giving a corresponding distance from the environment detection sensor (2) to the object (O) for the environment detection sensor (2) for a plurality of different detection conditions, from which the environment detection sensor (2) can detect the object (O), wherein the object information of the object (O) farthest from the environment detection sensor (2) is called from the digital map and the detection condition is determined accordingly, the distance assigned to the environment detection sensor (2) by the detection condition being most relevant to the current sensor effective range determined for the environment detection sensor (2), Detection conditions determined by a plurality of environment detection sensors (2) of a vehicle (1) are compared with each other.

2. The method according to claim 1, characterized in that The distance from the environment detection sensor (2) to the object (O) is determined as the current sensor effective range of the environment detection sensor (2).

3. The method according to claim 1 or 2, characterized in that: The object information of the corresponding object (O) is determined by detecting the corresponding object (O) with the aid of the environment detection sensor (2) and / or with the aid of an environment detection sensor (2) of the same type and fusing and evaluating the corresponding existing detection conditions. The object information at least gives the corresponding distance from the environment detection sensor (2) to the object (O) for the environment detection sensor (2) under a plurality of different detection conditions, and from which distance the environment detection sensor (2) can detect the object (O).

4. The method according to claim 1 or 2, characterized in that: The detection conditions determined based on the plurality of objects (O) are compared with each other.

5. The method according to claim 1 or 2, characterized in that: The current effective road surface detection range of the environment detection sensor (2) is determined by means of an environment detection sensor (2) constructed as an optical sensor, and the current road surface condition is determined based on the stored road surface condition and the assigned road surface detection effective range.

6. The method according to claim 3, characterized in that: The correspondingly existing detection conditions are weather conditions.

7. The method according to claim 1 or 2, characterized in that: The current road surface detection effective range of the environment detection sensor (2) is determined by means of an environment detection sensor (2) constructed as a laser radar sensor or an image detection sensor, and the current road surface condition is determined based on the stored road surface condition and the assigned road surface detection effective range.

8. The method according to claim 1 or 2, characterized in that: The current road surface detection effective range of the environment detection sensor (2) is determined by means of an environment detection sensor (2) constructed as a video sensor, and the current road surface condition is determined based on the stored road surface condition and the assigned road surface detection effective range.

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