Method and device for vehicle measurement

Abstract

A method for checking the correct positioning of a vehicle on a measuring station for vehicle measurement includes: a) taking images of at least two tires of the vehicle; b) identifying features, in the images taken, which describe at least one area of the respectively recorded tire; c) fitting a mathematical model to the identified features; d) determining the extent of the flattening of each tire from the fitted mathematical model; e) comparing the flattening of the at least two tires.

Claims

1. A method for checking a correct positioning of a vehicle on a measuring station for vehicle measurement, the method comprising: taking images of at least two tires of the vehicle; identifying features in the images taken, which describe at least one area of the respectively recorded tire; fitting a mathematical model to the identified features; determining the extent of the flattening of each tire from the fitted mathematical model; comparing the flattening of the at least two tires; taking at least one image of each tire of the vehicle while the vehicle is passing by; determining turning centers of the wheels from the mathematical model; and checking whether the turning centers of the wheels have moved in one plane while the vehicle was passing by.

2. The method of claim 1, further comprising: emitting a warning and/or blocking a planned vehicle measurement, if the difference in the flattening of the tires exceeds a specified boundary value.

3. The method of claim 1, wherein the tires are each illuminated by a projector.

4. The method of claim 1, wherein stereo images of the tires are taken using a stereo camera.

5. The method of claim 1, wherein the mathematical model is a two-dimensional model or a three-dimensional mathematical model.

6. A device for checking a correct positioning of a vehicle on a measuring station for the vehicle measurement, using at least two sensing devices, which are each configured to take images of a tire of the vehicle, comprising: an evaluation device configured to perform the following: identify features in the images taken, which describe at least one area of the respectively recorded tire; fit a mathematical model to the identified features; determine the extent of the flattening of each tire from the fitted mathematical model; and compare the flattening of at least two tires to one another; taking at least one image of each tire of the vehicle while the vehicle is passing by; determining turning centers of the wheels from the mathematical model; and checking whether the turning centers of the wheels have moved in one plane while the vehicle was passing by.

7. The device of claim 6, wherein the evaluation device is integrated into at least one of the sensing devices.

8. The device of claim 6, wherein the device has four sensing devices.

9. The device of claim 6, further comprising: an emitting arrangement to emit a warning and/or blocking a planned vehicle measurement, if the difference in the flattening of the tires exceeds a specified boundary value.

10. The device of claim 6, wherein the tires are each illuminated by a projector.

11. The device of claim 6, wherein stereo images of the tires are taken using a stereo camera.

12. The device of claim 6, wherein the mathematical model is a two-dimensional model or a three-dimensional mathematical model.

13. A device for vehicle measurement, comprising: an arrangement for checking a correct positioning of a vehicle on a measuring station for the vehicle measurement, using at least two sensing devices, which are each configured to take images of a tire of the vehicle, the arrangement including an evaluation device configured to perform the following: identify features in the images taken, which describe at least one area of the respectively recorded tire; fit a mathematical model to the identified features; determine the extent of the flattening of each tire from the fitted mathematical model; and compare the flattening of at least two tires to one another; taking at least one image of each tire of the vehicle while the vehicle is passing by; determining turning centers of the wheels from the mathematical model; and checking whether the turning centers of the wheels have moved in one plane while the vehicle was passing by.

14. The device of claim 13, further comprising: an emitting arrangement to emit a warning and/or blocking a planned vehicle measurement, if the difference in the flattening of the tires exceeds a specified boundary value.

15. The device of claim 13, wherein the tires are each illuminated by a projector.

16. The device of claim 13, wherein stereo images of the tires are taken using a stereo camera.

17. The device of claim 13, wherein the mathematical model is a two-dimensional model or a three-dimensional mathematical model.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a schematic top view of a measuring station for vehicle measurement.

(2) FIG. 2 shows an example of a 3D-point cloud, taken by a sensing device situated next to the left front wheel of a motor vehicle.

DETAILED DESCRIPTION

(3) FIG. 1 shows a schematic top view of a measuring station for vehicle measurement.

(4) The measuring station shows two rails 14 arranged in parallel to each other, which may be rails 14 of a car lift. Rails 14 may also be installed in a fixed manner on the floor of the measuring station, however. Alternatively, the method may also be carried out without rails 14 on the floor of the measuring station.

(5) In an area shown on the left in FIG. 1, each of the two rails 14 is equipped with a turntable 16, which makes it possible to turn in the steerable wheels of a vehicle situated on rails 14, when the vehicle is situated on the rails 14 in such a way that its steerable wheels are supported on turntables 16.

(6) In an area shown on the right-hand side in FIG. 1, rails 14 each have a sliding plate 18. Sliding plates 18 are slidable parallel to the longitudinal extension of rails 14, and may thus be situated at a variable distance from associated turntable 16. In this way, the measuring station is able to be adapted to various vehicles that have different distances between the front wheels and the rear wheels.

(7) In a rectangular set-up, four sensing devices 20 are situated about rails 14. Two (front) sensing devices 20 are situated level with turntables 16, and thus situated next to the usually steerable front wheels of a vehicle parked on rails 14. Two (rear) sensing devices 20 are able to be moved along rails 14, so that their position is able to be adapted in such a way to the wheelbase of the vehicle to be measured that rear sensing devices 20 are always positioned opposite the rear wheels of the vehicle parked on rails 14.

(8) Each of sensing devices 20 has an image-taking device (image sensor) 22 for recording measured values, which is configured as a (stereo) camera, for instance, and an integrated illuminating device 23, which is configured to illuminate the wheel to be measured that lies opposite respective sensing device 20.

(9) Each of sensing devices 20 may also have position lights 21 and an optical sensor 24 each, in order to be able to determine the position of the respective sensing device 20 with reference to at least two others of sensing devices 20.

(10) Sensing devices 20 are connected via data lines 12 to a central evaluation device 10. Alternatively, sensing devices 20 may be connected in a wireless manner to central evaluation device 10. Evaluation device 10 may also be situated in one or more of sensing devices 20.

(11) FIG. 2 shows an example of a 3D-point cloud, as it is recorded by a sensing device 20, which is situated at left front wheel 8 of a vehicle.

(12) The appertaining of the recorded points to wheel 8, to the car's body 2, for instance, wheelhouse 4 and to roadway 34, 36 is determined by the combination of intelligent image-processing algorithms. From the points assigned to tire 7 of wheel 8, those particular points 7a are identified which belong to the lower region of tire 7 which is flattened based on the curb weight of the vehicle.

(13) A mathematical model, particularly a so-called spline model, is fitted to the points representing tire 7, and in particular to points 7a of the lower, flattened region of tire 7. The flattening of tire 7 may then be determined from the parameters of the mathematical model.

(14) This process is carried out for at least two tires 7 of the vehicle, and the flattening incidences of tire 7 are compared to one another. If the differences of the extent of the flattenings between different tires 7 of a vehicle exceed a specified boundary value, a warning signal is emitted and/or a planned vehicle measurement is prevented, since upon the exceeding of the boundary value, the vehicle measurement is no longer able to be carried out at the accuracy required, but would lead to false results.

(15) In one broadened specific embodiment, one or more images are taken of each wheel 8, while the vehicle travels onto, or over the measuring station. From the at least one image taken, one may additionally determine the turning center Z of each wheel 8. A method suitable for this is described in DE 10 2006 048 725 A1 for example.

(16) In the following it may be established whether the turning centers Z of wheels 8 move in one plane during its travel onto the measuring station, i.e. whether the plane of the measuring station is really flat. In this case, too, a warning is emitted and/or the measurement is terminated if the unevenness of the measuring station exceeds a specified limit, so that an error-free measurement is no longer possible.

(17) Consequently, the present invention makes it possible conveniently and reliably to check the prerequisites for a successful vehicle measurement, particularly a horizontal orientation of the vehicle body.