Method for the Determination of the Wheel Geometry and/or Axle Geometry of Motor Vehicles

• US 20080319706A1
• Filed: 04/11/2006
• Published: 12/25/2008
• Est. Priority Date: 04/15/2005
• Status: Active Grant

• Current Assignee: Beissbarth Automotive Testing Solutions GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Uffenkamp, Volker, Nobis, Guenter
• Granted Patent: US 8,254,666 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G01B 11/275 for testing wheel alignment
• CPC Class Codes: G01B 2210/146 Two or more cameras imaging the same area
• CPC Class Codes: G01B 2210/20 Vehicle in a state of translatory motion
• CPC Class Codes: G01B 2210/286 Projecting a light pattern on the wheel or vehicle body

Abstract

The invention relates to a method for determining the wheel geometry and/or axle geometry of motor vehicles by means of an optical measuring apparatus. According to said method, at least two recording points are assigned to each other and are referenced in relation to the measuring space with the aid of an image recording system, optionally taking into account reference characteristics and vehicle body characteristics, an object segment (6) comprising the wheel (5) that is to be measured is detected from different perspectives, and the position of wheel characteristics in the measuring space is evaluated during the measurement. In order to create an advantageous procedure regarding the operation and the accuracy of the measurement, a plurality of individual 3D pixels representing the three-dimensional surface of the object segment that is detected by the at least two image recording devices (2) are determined from the object segment using image processing methods by correlating images, and the wheel characteristics and/or reference characteristics and/or vehicle body characteristics are obtained therefrom.

Claims

1. A method for determining the wheel geometry and/or axle geometry of motor vehicles using an optical measuring device, with which—

while optionally taking into account reference features and vehicle body features—

an image recording system that includes at least two image recording devices (2) for creating digital images is used to assign at least two recording points to each other and perform referencing relative to the measurement space, an object section (6) including the wheel to be measured is registered from different perspectives, and the position of wheel features in the three-dimensional measurement space is evaluated in the measurement,

wherein

a 3D group of points is ascertained from the object section registered two-dimensionally by the at least two image recording devices (2) from different perspectives using image processing methods with correlation of images—

the 3D group of points representing the three-dimensional surface with several individual 3D image points—

and the wheel features and/or reference features and/or vehicle body features are ascertained therefrom as a point, a 2D function, a 3D function, or a 3D surface.

2. The method as recited in claim 1,

wherein

the information provided by the 3D group of points is used directly to extract the wheel features, or an intermediate step is carried out to derive a surface model from the 3D group of points, then the wheel features are extracted from the surface model in a subsequent, second step.

3. The method as recited in claim 2,

wherein,

based on the 3D group of points, a three-dimensional surface model is ascertained, as a contour model, a regular grid, or via triangulation.

4. The method as recited in claim 1,

wherein,

in addition to the wheel features, at least one key vehicle body feature is obtained in the same manner.

5. The method as recited in claim 4,

wherein

the determination of the wheel geometry and/or axle geometry is carried out when the motor vehicle drives past the image recording devices (2);

the motion of the motor vehicle relative to the image recording devices is determined based on the at least one vehicle body feature, and at least one wheel feature of the wheel (5) to be measured is extracted from the surface structure of the detected object section (6) at several or all image recording instants as the vehicle passes by.

6. The method as recited in claim 1,

wherein

the wheel (5) to be measured is checked in the evaluation device for rim runout with reference to at least one extracted, significant wheel feature and with reference to at least two further wheel features, and the rim runout is taken into account in the future evaluation, if necessary.

7. The method as recited in claim 1,

wherein

the assignment of the recording locations to each other and the referencing are carried out based on an additional reference feature assignment carried out in the measurement space, and/or based on reference features ascertained from key structures present anyway in the measurement space, using the methods stated in claim 1.

8. The method as recited in claim 1,

wherein

patterns are projected onto the wheel (5), the vehicle body, and/or in the measurement space using at least one projector.

9. The method as recited in claim 1,

wherein

a partially different density and/or a partially different grid is produced in the 3D group of points and/or in the three-dimensional surface model before the wheel and/or vehicle body features are extracted.

10. The method as recited in claim 1,

wherein

the amount of data taken into account in the evaluation is reduced by eliminating the image points of uninteresting image regions that were recorded, either before the 3D group of points is ascertained from the 2D image points, or after the 3D group of points is ascertained from the 3D image points.

11. The method as recited in claim 1,

wherein

preliminary information about the vehicle body and/or wheel to be measured, e.g., the tire diameter and/or rim diameter and/or rim shape, is supplied to the image processing device.