METHOD FOR DETERMINING AT LEAST ONE TYRE-SPECIFIC CHARACTERISTIC, DRIVER ASSISTANCE SYSTEM AND MOTOR VEHICLE

Abstract

The invention relates to a method for determining at least one tyre-specific characteristic of a tyre (15) of a motor vehicle (1), in which an area of the tyre (15) of the motor vehicle (1) is captured by means of at least one vehicle-side camera (3, 6), wherein a tyre wall (16) of the tyre (15) with a tyre inscription (19) is captured as the area by means of the at least one camera (3, 6), and the tyre inscription (19) is identified by means of an evaluation device (13) and the at least one tyre-specific characteristic is determined on the basis of the tyre inscription (19). The invention also relates to a driver assistance system (2) and a motor vehicle (1).

Claims

1. A method for determining at least one tyre-specific characteristic of a tyre of a motor vehicle, comprising: capturing an area of the tyre of the motor vehicle by at least one vehicle-side camera; capturing a tyre wall of the tyre with a tyre inscription as the area by the at least one camera; identifying the tyre inscription by an evaluation device; and determining the at least one tyre-specific characteristic on the basis of the tyre inscription.

2. The method according to claim 1, wherein tyre manufacturer and/or at least a tyre size designation and/or an indicator of weather suitability is captured and identified as the tyre inscription.

3. The method according to claim 2, wherein characteristics are provided for predetermined tyre manufacturers and/or predetermined tyre size designations and the associated characteristic is selected on the basis of the captured and identified tyre manufacturer and/or the at least one captured and identified tyre size designation and is determined as the at least one tyre-specific characteristic.

4. The method according to claim 2, wherein a tyre-specific tread depth is determined as the at least one tyre-specific characteristic on the basis of the captured and identified tyre manufacturer and/or the captured and identified tyre size designation and/or on the basis of the captured and identified indicator of weather suitability.

5. The method according to claim 1, wherein a tread of the tyre of the motor vehicle is captured by the at least one camera at least partially and in addition a current tread depth of the tyre, for capturing a state of wear of the tyre, is captured and determined on the basis of the captured tread.

6. The method according to claim 2, wherein a tyre-specific water displacement capacity of the tyre is determined on the basis of the tyre manufacturer and/or at least the tyre size designation and/or the indicator of weather suitability, wherein the tyre-specific water displacement capacity describes a tyre-specific amount of water on a carriageway of the motor vehicle, above which the tyre floats on the carriageway.

7. The method according to claim 6, wherein current amount of water on the carriageway of the motor vehicle is determined and a current difference value between the tyre-specific and the current amount of water is formed, wherein warning levels for a floating of the tyre are provided for predetermined difference values and one of the warning levels is selected as a function of the current difference value.

8. The method according to claim 7, wherein an output device is provided in the motor vehicle, wherein the warning levels are output by the output device as warning signals to a driver of the motor vehicle.

9. The method according to claim 2, wherein at least one geometric characteristic of the tyre comprising, a track width and an offset of a rim of the tyre is determined as the tyre-specific characteristic on the basis of the captured and identified tyre size designation.

10. The method according to claim 9, wherein the at least one tyre-specific geometric characteristic is provided for calculating odometry parameters of the motor vehicle.

11. The method according to claim 10, wherein a course of movement of the motor vehicle is determined for a driver assistance system in a parking operation of the motor vehicle supported by the driver assistance system on the basis of the calculated odometry parameters.

12. The method according to claim 1, wherein the at least one camera is arranged on a side mirror of the motor vehicle, wherein a tyre of a front wheel of the motor vehicle (1) of a motor vehicle side associated with the side mirror and a tyre of a rear wheel of the motor vehicle of the motor vehicle side associated with the side mirror is at least partially in a capture range of the at least one camera.

13. The method according to claim 1, wherein a steering angle of the motor vehicle is captured and, on the basis of the steering angle, it is determined whether the tyre wall of the tyre is located in a capture range of the at least one camera, wherein the capture and identification of the tyre inscription is initiated as soon as the tyre wall of the tyre is within the capture range of the at least one camera.

14. A driver assistance system for a motor vehicle, comprising: at least one vehicle-side camera for detecting an area of a tyre of the motor vehicle, wherein the at least one camera is captures a tyre wall having a tyre inscription as the area of the tyre; and an evaluation device of the driver assistance system for identifying the tyre inscription and, on the basis of the tyre inscription, to determine at least one tyre-specific characteristic of the tyre of the motor vehicle.

15. A motor vehicle having a driver assistance system according to claim 14.

Description

[0028] In the following, the invention will be explained in more detail with reference to a preferred embodiment as well as with reference to the accompanying drawings, in which:

[0029] FIG. 1 shows a schematic representation of an embodiment of a motor vehicle according to the invention;

[0030] FIG. 2 shows a schematic representation of a tyre of a motor vehicle in a side view;

[0031] FIG. 3 shows a schematic representation of a tyre of a motor vehicle from the perspective of a camera of the motor vehicle; and

[0032] FIG. 4 shows a further schematic representation of a tyre of a motor vehicle from the perspective of a camera of the motor vehicle.

[0033] Identical and functionally identical elements are provided with the same reference numerals in the figures.

[0034] FIG. 1 shows a motor vehicle 1 with a driver assistance system 2. The driver assistance system 2 is configured in particular as a parking assistant or an aquaplaning assistant. The driver assistance system 2 comprises a first camera 3, which is arranged in a first side mirror 4 on a first side 5. In addition, the driver assistance system 2 comprises a second camera 6 which is arranged in a second side mirror 7 on a second side 8 of the motor vehicle 1 opposite the first side 5.

[0035] In a capture range of the first camera 3, there is a first front wheel 9 of the motor vehicle 1 and a first rear wheel 10 of the motor vehicle 1. In a capture range of the second camera 6, there is a second front wheel 11 of the motor vehicle 1 and a second rear wheel 12 of the motor vehicle 1. Each of the wheels 9, 10, 11, 12 has a tyre 15 via which the respective wheel 9, 10, 11, 12 can be rolled for locomotion of the motor vehicle 1 on a carriageway of the motor vehicle 1. The cameras 3, 6 are now designed to capture at least an area of the tyres 15 of the wheels 9, 10, 11, 12 in images.

[0036] FIG. 2 shows one of the wheels 9, 10, 11, 12 in a side view. The wheel 9, 10, 11, 12 has the tyre 15 and a rim 17 on which the tyre 15 bears. The tyre 15 comprises a tread 18 which, when the wheel 9, 10, 11, 12 rolls, touches the carriageway of the motor vehicle 1 at least in areas. Side walls, so-called tyre walls, adjoin the tread 18, of which an outer tyre wall 16 facing a surrounding area of the motor vehicle 1 is shown here. The tyre wall 16 of the tyre 15 is provided with a tyre inscription 19. The tyre inscription 19 comprises alphanumeric characters and/or symbols, by which tyre-specific characteristics are stored or described in coded form or directly.

[0037] In this case, the tyre inscription 19 may comprise a tyre manufacturer 20 in the form of a lettering, which in particular identifies a brand and a tyre type of the tyre 15. A tyre course of profile and/or a tyre tread depth of the tyre 15 can be determined through the tyre manufacturer 20, for example. In addition, tyre size designations 21 of the tyre 15 can be represented by means of the tyre inscription 19. These tyre size designations 21 may indicate geometrical characteristics and other characteristic numbers of the tyre 15, for example, in the form of combinations of code letters and code numbers. The corresponding tyre-specific, geometric parameters can be assigned to the code letters and code numbers, for example, in a table. Such tyre size designations 21 are, for example, a tyre width, a tyre diameter, a rim diameter, a tyre height-to-width ratio, a tyre cross-sectional width, a tyre contact area, an air pressure of the tyre 15, a track width, a tyre load capacity index 15, and a speed index. In addition, the tyre inscription 19 may include a manufacturer's date 22 in coded form as well as an indicator of weather suitability 23 which identifies the tyre 15 as a winter or all-season tyre.

[0038] The tyre wall 16 of the wheels 9, 10, 11, 12 having the tyre inscription 19 is captured in images in this case by the cameras 3, 6 of the driver assistance system 2 of the motor vehicle 1. For this purpose, an image 24 of the tyre wall 16 of the tyre 15 of the wheel 9 having the tyre inscription 19 captured by the camera 3 is shown by way of example in FIG. 3. It can be seen in this case that the tyre wall 16, and thus the tyre inscription 19, are in the capture range of the camera 3, in particular, when the wheel 9 has been turned in. In order to detect the turned-in state of the wheel 9, a steering angle of the motor vehicle 1 can be captured by means of a steering angle sensor (not shown here). Once it has been captured by the steering angle sensor that the wheel 9 is turned in in such a way that the tyre inscription 19 is located in the capture range of the camera 3, a capture process of the tyre inscription 19 is started.

[0039] For this purpose, the driver assistance system 2 comprises an evaluation device 13, which is designed to evaluate the captured images 24 of the cameras 3, 6. The evaluation device 13 includes, for example, an image processing device and extracts or identifies the tyre inscription 19 from the tyre wall 16 captured by the cameras 3, 6. On the basis of the tyre inscription 19, the evaluation device 13 determines at least one of the tyre-specific characteristics of the tyre 15. For this purpose, tyre-specific characteristics corresponding to predetermined tyre inscriptions can be stored, for example, in a vehicle-internal database and/or vehicle-external, for example Internet-based, database (not shown here). The evaluation device 13 is designed in this case to read this database and to detect or determine the associated tyre-specific characteristic based on the captured and identified tyre inscription 19.

[0040] The determined tyre-specific characteristics can be further processed by the driver assistance system 2. Thus, for example, a driver assistance system 2 configured as a parking assistance system can use the tyre-specific characteristics, in particular the track width and the tyre air pressure 15, to determine in more detail odometry parameters for the motor vehicle 1 during a parking operation of the motor vehicle 1 supported by the driver assistance system 2. So far, standard values for the tyres 15 have usually been specified, but these were too inaccurate for an exact determination of the odometry parameters of the motor vehicle 1.

[0041] In a driver assistance system 2 embodied as an aquaplaning assistant, the tyre-specific characteristics of the tyre 15, in particular the tread pattern course and/or the tread pattern depth, can be used to determine a tyre-specific water displacement capacity of the tyre 15. Through the tyre-specific water displacement capacity, a tyre-specific amount of water for the tyres 15 is determined, in the presence of which on the carriageway of the motor vehicle 1, the tyres 15 of the motor vehicle 1 float on the carriageway. In order to determine the tyre-specific water displacement capacity even more precisely, the cameras 3, 6 and the evaluation device 13 can also determine a current profile 26, in particular a current tread depth, of the tyre 15.

[0042] In FIG. 4, an image 25 of the wheel 9 captured by the camera 3 shows that the tread 18 of the tyre 15 of the wheel 9 with the current profile 26 is captured for this purpose. On the basis of the captured profile 26, the evaluation device 13 can determine the current tread depth of the tyre 15, which characterizes a wear of the tyre 15 of the wheel 9 and which in particular influences the floating time of the tyre 15 in aquaplaning.

[0043] The driver assistance system 2 can also have an output device 14, for example in the form of a display device or a loudspeaker. For example, a risk of aquaplaning can be signalled to a driver of the motor vehicle 1 by means of the output device 14. For this purpose, a current amount of water on the carriageway of the motor vehicle 1 can be determined, for example by a detection device (not shown here), and compared with the tyre-specific amount of water. The smaller a difference between the tyre-specific and the current amount of water, the greater the risk of aquaplaning. This can be communicated to the driver by means of the output device 14, for example by means of a signal tone or a warning light.