Abstract
A trailer angle determination system for a vehicle is provided. The trailer angle determination system has a sensing unit for sensing a trailer connected to the vehicle and an evaluation unit. The sensing unit is arranged outside of the center of the vehicle and toward the trailer, and the distance between the sensing unit and the center of the vehicle is known. The trailer has symmetrical feature pairs with respect to a longitudinal axis of symmetry of the trailer. The sensing unit is designed to sense the symmetrical feature pairs of the trailer. The evaluation unit is designed to determine the angle between the trailer and the vehicle based on the sensed symmetrical feature pairs of the trailer and the known distance between the sensing unit and the center of the vehicle.
Claims
1. A trailer angle determination system for a vehicle, the system comprising: a sensing unit sensing a trailer connected to the vehicle; and an evaluation unit, wherein the sensing unit is arranged outside of the center of the vehicle and toward the trailer, and wherein a distance between the sensing unit and the center of the vehicle is known, wherein the trailer has symmetrical feature pairs with respect to a longitudinal axis of symmetry of the trailer, wherein the sensing unit is designed to sense the symmetrical feature pairs of the trailer, wherein the evaluation unit is designed to determine the angle between the trailer and the vehicle on the basis of the sensed symmetrical feature pairs of the trailer and the known distance between the sensing unit and the center of the vehicle.
2. The trailer angel determination system according to claim 1, wherein the determined angle is used by a driver assistance system of the vehicle.
3. The trailer angle determination system according to claim 1, wherein the sensing unit is a mono-camera and senses image data of the trailer.
4. The trailer angle determination system according to claim 3, wherein the evaluation unit is designed to determine at least two feature pairs which are symmetrical to the longitudinal axis of symmetry of the trailer in the image data of the sensing unit and to determine the angle between the trailer and the vehicle on the basis of the sensed feature pairs.
5. The trailer angle determination system according to claim 3, wherein the evaluation unit is designed to determine the distance between the trailer and the vehicle on the basis of the distance between the sensing unit and the center of the vehicle and the positions of the at least two symmetrical feature pairs of the trailer in the image data.
6. The trailer angle determination system according to claim 5, wherein the distance between the vehicle and the trailer is calculated according to this formula: wherein x is the distance between the vehicle and the trailer, y.sub.c is the distance between the sensing unit and the center of the vehicle, and .sub.r and .sub.l are the angles of the features of the feature pair with respect to the main visual axis of the sensing unit.
7. The trailer angle determination system according to claim 5, wherein the evaluation unit is designed to determine the distance between the vehicle and the trailer by an initialization on the basis of a single image, in which the center of the vehicle and the longitudinal axis of symmetry of the trailer are in a line.
8. A vehicle having a trailer angle determination system, the trailer angle determination system comprising: a sensing unit sensing a trailer connected to the vehicle; and an evaluation unit, wherein the sensing unit is arranged outside of the center of the vehicle and toward the trailer, and wherein the distance between the sensing unit and the center of the vehicle is known, wherein the trailer has symmetrical feature pairs with respect to a longitudinal axis of symmetry of the trailer, wherein the sensing unit is designed to sense the symmetrical feature pairs of the trailer, wherein the evaluation unit is designed to determine the angle between the trailer and the vehicle on the basis of the sensed symmetrical feature pairs of the trailer and the known distance between the sensing unit and the center of the vehicle.
9. The vehicle according to claim 8, wherein the sensing unit is a mono-camera and senses image data of the trailer.
10. The vehicle according to claim 9, wherein the evaluation unit is designed to determine at least two feature pairs which are symmetrical to the longitudinal axis of symmetry of the trailer in the image data of the sensing unit and to determine the angle between the trailer and the vehicle on the basis of the sensed feature pairs.
11. The vehicle according to claim 9, wherein the evaluation unit is designed to determine the distance between the trailer and the vehicle on the basis of the distance between the sensing unit and the center of the vehicle and the positions of the at least two symmetrical feature pairs of the trailer in the image data.
12. The vehicle according to claim 11, wherein the distance between the vehicle and the trailer is calculated according to this formula: wherein x is the distance between the vehicle and the trailer, y.sub.c is the distance between the sensing unit and the center of the vehicle, and .sub.r and .sub.l are the angles of the features of the feature pair with respect to the main visual axis of the sensing unit.
13. The vehicle according to claim 11, wherein the evaluation unit is designed to determine the distance between the vehicle and the trailer by an initialization on the basis of a single image, in which the center of the vehicle and the longitudinal axis of symmetry of the trailer are in a line.
14. A method for determining the angle between a vehicle and a trailer connected to the vehicle, having the following steps: sensing the trailer by a sensing unit which is arranged outside of the center of the vehicle toward the trailer; determining the distance between the sensing unit and a center of the vehicle; sensing symmetrical feature pairs with respect to the longitudinal axis of symmetry of the trailer; determining the distance between the vehicle and the trailer if the longitudinal axis of symmetry of the trailer and the center of the vehicle are in a line; and determining the angle between the vehicle and the trailer on the basis of the symmetrical feature pairs of the trailer and the known distance between the sensing unit and the center of the vehicle for use by a driver assistance system of the vehicle.
15. A program item which, if it is executed by an evaluation unit of a trailer angle determination system, instructs the evaluation unit to perform the method according to claim 14.
16. A computer-readable medium, on which a program item is stored according to claim 12.
Description
DESCRIPTION OF DRAWINGS
[0028] FIG. 1 shows a block diagram of an exemplary trailer angle determination system.
[0029] FIG. 2 shows a schematic depiction of a vehicle having an exemplary trailer angle determination system and a trailer.
[0030] FIG. 3 shows a schematic depiction of the features of the trailer recognized by the exemplary trailer angle determination system.
[0031] FIG. 4 shows a schematic depiction of the exemplary calculation of the distance between the vehicle and the trailer.
[0032] FIG. 5 shows a schematic depiction of the possible positions of the features of the trailer from the viewpoint of the exemplary trailer angle determination system.
[0033] FIG. 6 shows the exemplary trailer angle determination system which has determined the angle between the vehicle and the trailer.
[0034] FIG. 7 shows a vehicle having an exemplary trailer angle determination system.
[0035] FIG. 8 shows a flow chart for an exemplary method for determining an angle between a vehicle and a trailer.
[0036] Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION
[0037] FIG. 1 shows a block diagram of a trailer angle determination system 1. The trailer angle determination system 1 has a sensing unit 20 and an evaluation unit 10. The sensing unit 20 is configured to sense image data of a trailer which is connected to the vehicle of the trailer angle determination system 1. Moreover, the trailer has symmetrical feature pairs with respect to a longitudinal axis of symmetry of the trailer. The sensing unit 20 is additionally arranged outside of the center of the vehicle and has a parallel alignment with respect to the center of the vehicle. The evaluation unit 10 can determine the angle between the vehicle and the trailer on the basis of the sensed image data of the sensing unit 20 and the known distance between the sensing unit 20 and the center of the vehicle. The sensing unit 20 can additionally determine the angle, along the line of sight of the sensing unit 20, at which angle an object or respectively a feature is located with respect to the sensing unit. For the calibration, the trailer angle determination system 1 merely needs an image or respectively a frame of the sensing unit 20, in the case of which the center of the vehicle and the longitudinal axis of symmetry of the trailer are in a line. As a result, the distance between the vehicle and the trailer or respectively the features of the feature pair of the trailer can be determined.
[0038] FIG. 2 shows a schematic depiction of the trailer angle determination system on a vehicle 2. To this end, a sensing unit 20, e.g. a camera, is arranged on the vehicle 2. The vehicle 2 has a center 21 (longitudinal axis of the vehicle) (depicted as a dashed line). The sensing unit is deliberately arranged outside of said center 21 of the vehicle 2 in the distance y.sub.c. A trailer 3 is additionally connected to the vehicle via a rotatable coupling 4. The trailer likewise has a longitudinal axis of symmetry 31 (depicted as a dashed line). The distance between the vehicle and the trailer is designated x. The trailer 3 has symmetrical features 35, 36, 37, 38 with respect to its longitudinal axis of symmetry 31. These features 35, 36, 37, 38 are, in each case, used in pairs 35, 38; 36, 37 in order to determine the angle between the vehicle 2 and the trailer 3. Moreover, the sensing unit 20 can sense the symmetrical features 35, 36, 37, 38 of the trailer 3 and the evaluation unit can evaluate these in such a way that the angle between the vehicle 2 and the trailer 3 can be determined. The angle is, in this connection, the angle between the longitudinal axis or respectively the center 21 of the vehicle 2 and the longitudinal axis of symmetry 31 of the trailer 3.
[0039] FIG. 3 likewise shows a schematic depiction of the trailer angle determination system. Unlike FIG. 2, the trailer and the coupling between the trailer and the vehicle 2 have been removed for reasons of clarity. Moreover, the distance y.sub.1 between the first feature pair 35, 38 and the distance y.sub.2 between the second feature pair 36, 37 are depicted. In this connection, it should be pointed out that the distance between the longitudinal axis of symmetry 31 of the trailer and the features of the first feature pair 35, 38 is the same and is 0.5*y.sub.1. The distance between the longitudinal axis of symmetry 31 of the trailer and the features of the second feature pair 36, 37 is additionally the same and is 0.5*y.sub.2.
[0040] FIG. 4 shows a schematic view of the determination of the distance between the vehicle and the trailer if the center 21 of the vehicle and the longitudinal axis of symmetry 31 of the trailer are the same. To this end, an image or respectively a frame having symmetrical feature pairs of the trailer is needed in this case. The sensing unit 20 is, in this connection, deliberately arranged outside of the center 21 of the vehicle, and the distance y.sub.c between the center 21 of the vehicle and the sensing unit 20 is known. Moreover, the angle l, r is known by the sensing unit 20, at which the image data of the respective symmetrical features of the feature pair are received. The sensing unit 20 senses at least one symmetrical feature pair 35, 38 of the trailer. In this connection, the distance y.sub.l, y.sub.r between the respective feature 35, 38 and the longitudinal axis of symmetry 31 of the trailer is identical and corresponds in each case to 0.5*y.sub.1. Two right triangles can now be formed from the viewpoint of the sensing unit 20. The first right triangle includes the first feature 35 of the first feature pair 35, 38 and the distance x between the vehicle and the trailer and the second right triangle includes the second feature 38 of the first feature pair 35, 38 and the distance x. Due to the arrangement of the sensing unit 20 at a distance y.sub.c from the center 21 of the vehicle, the length of the opposite side of the first right triangle can be described as y.sub.l+y.sub.c or respectively as 0.5*y.sub.l+y.sub.c and the length of the opposite side of the second right triangle can be described as y.sub.ry.sub.c or respectively as 0.5*y.sub.ly.sub.c. The length of the adjacent side of the first right triangle and the length of the adjacent side of the second right triangle are identical and correspond to the distance x between the vehicle and the trailer. Additionally, 0.5*y.sub.l+y.sub.c equals x*tan(.sub.l) and 0.5*y.sub.ly.sub.c equals x*tan(.sub.r). It is also true that, due to the symmetry of the features 35, 38, 0.5*y.sub.l is equal to x*tan(.sub.l)y.sub.c and is simultaneously equal to x*tan(.sub.r)+y.sub.c. Consequently, these two formulas can be equated to 0.5*y.sub.l and solved for x in such a way that
[00003]
applies. Consequently, the distance x between the vehicle and the trailer can be determined depending on the known distance y.sub.c between the sensing unit and the longitudinal axis of symmetry of the trailer and the known angles, at which the first feature pair 35, 38 has been sensed by the sensing unit 20.
[0041] FIG. 5 shows a schematic depiction of the correct distance determination of the individual feature pairs 35, 38; 36, 37. In this connection, the dotted circles symbolize the possible positions of the features from the viewpoint of the sensing unit 20 along the lines of sight of the sensing unit 20. These can be located at any position along the line of sight (dashed arrow starting from the sensing unit 20). The solid circles symbolize the actual positions of the features 35, 36, 37, 38 of the trailer 3. The actual position of the respective feature pairs 35, 38; 36, 37 can be determined by the method which has been described with reference to FIG. 4. The angle between the vehicle 2 and the trailer 3 can be subsequently determined during the operation of the trailer angle determination system with the determined positions of the symmetrical feature pairs 35, 38; 36, 37 during the initialization.
[0042] FIG. 6 shows the trailer angle determination system during operation. Here, the angle between the vehicle 2 and the trailer 3 is not equal to 0 or respectively 180, where the trailer 3 has rotated around the coupling 4. The symmetrical feature pairs 35, 38; 36, 37 change, due to the rotation, the angle of the line of sight between the respective feature 35, 36, 37, 38 and the sensing unit 20. Due to the change in the angle of the line of sight of the at least two symmetrical feature pairs 35, 38; 36, 37 and the previously known distance x between the vehicle 2 and the trailer 3, the angle a between the vehicle 2 and the trailer 3 can be extrapolated by the evaluation unit. In a further example, the position of the coupling 4 and, consequently, of the center of rotation can additionally be known, as a result of which the calculation of the angle a between the vehicle 2 and the trailer 3 can be simplified.
[0043] FIG. 7 shows a vehicle 2 having a trailer angle determination system 1 which is described above and below.
[0044] FIG. 8 shows a flow chart for a method for determining the angle between a vehicle and a trailer connected to the vehicle. In step S1, the trailer is sensed by the sensing unit, the sensing unit is, in this connection, arranged outside of the center toward the trailer. In step 2, the distance between the sensing unit and the center of the vehicle is determined. In step S3, symmetrical features of the trailer are sensed by the evaluation unit with respect to the longitudinal axis of symmetry of the trailer. In step S4, the distance between the vehicle and the trailer is determined if the center of the vehicle and the longitudinal axis of symmetry of the trailer are in a line. In step 5, the angle between the vehicle and the trailer is determined on the basis of the symmetrical features of the trailer and the known distance between the sensing unit and the center of the vehicle, as well as the determined distance between the vehicle and the trailer.
[0045] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.
