Device and method for a quality test of a body

• US 7,088,442 B2
• Filed: 12/13/2001
• Issued: 08/08/2006
• Est. Priority Date: 12/14/2000
• Status: Expired due to Term

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Kostka, Guenther, Schmitt, Peter, Hassler, Ulf
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Assistant Examiner(s): Nguyen, Sang H.
• Application Number:
  US10/433,994
• Publication Number:
  US 20040071334A1
• Time in Patent Office: 1,699 Days
• Field of Search: 3562371-2373, 356600-601, 356/394, 731/46, 731/462, 731/463, 731/465, 731/468, 250/559.29, 250/559.31, 250/559.4
• US Class Current: 356/237.1
• CPC Class Codes: G01B 11/2522 the position of the object changing and being recorded
• CPC Class Codes: G01B 21/20 for measuring contours or curvatures, e.g. determining profile
• CPC Class Codes: G01M 17/02 Tyres
• CPC Class Codes: G01M 17/027 using light, e.g. infrared, ultraviolet or holographic techniques
• CPC Class Codes: G01N 21/8851 Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/0006 using a design-rule based approach

Abstract

A device for quality testing of a body comprising a surface comprising a structuring bounded by edges and a substantially edge-free unevenness, wherein the structuring illustrates a quality impairment and wherein the unevenness illustrates a potential quality impairment, includes a means for generating a height representation, wherein the height representation of the surface includes the structuring and the unevenness. A means for calculating a variation representation calculates the variation associated to the point for every point of the height representation, so that at a boundary of the structuring a high variation is obtained, while at a boundary of the unevenness a low variation is obtained. A means for detecting regions which are potentially quality affecting detects regions as potentially quality-affecting which comprise a variation which is smaller than a predetermined variation threshold value regarding its magnitude. These potentially quality-affecting regions may then be further examined for different criteria to exclude the uncritical regions and to find out only the actually quality-affecting regions from the number of potentially quality-affecting regions. Thus, a safe quality control of vehicle tires on which a writing is attached as a structuring and which comprises bulges or constrictions as substantially edge-free unevennesses may be obtained.

Claims

1. An apparatus for quality testing a body having a surface comprising a structure bounded by eases and a substantially edge-tree unevenness, wherein the structure does not constitute a quality impairment, and wherein the unevenness constitutes a potential quality impairment, comprising:

a generator for generating a height representation of the surface, wherein the height representation of the surface includes the structure and the unevenness;

a calculator for calculating a variation representation from the height representation, wherein the variation representation includes variations of a height representation, so that at a boundary of the structure a high variation is obtained, wherein at a boundary of the unevenness a low variation is obtained; and

a detector for detecting regions of the height representation comprising a variation whose magnitude is smaller than a predetermined variation threshold value, wherein the variation threshold value is lower than the high variation and greater than the low variation, so that potentially quality-affecting regions are obtained.

2. The apparatus according to claim 1, wherein the detector is arranged to obtain only such regions as potentially quality-affecting whose height is larger than a predetermined detection threshold value.

3. The apparatus according to claim 1, further comprising:

an examiner for examining the potentially quality-affecting regions of the height representation regarding a height or depth and/or area in order to detect a quality-affecting unevenness.

4. The apparatus according to claim 3, wherein the examiner comprises:

a filter for non-linear two-dimensional filtering of the potentially quality-affecting regions to detect artifacts or small regions as not being quality-affecting.

5. The apparatus according to claim 3, wherein the examiner is arranged to determine the areas of the potentially quality-affecting regions and to compare the determined areas to at least one predetermined area threshold, to classify the potentially quality-affecting ranges as not being quality-affecting, whose areas are smaller than the predetermined area threshold.

6. The apparatus according to claim 5, in which a predetermined area threshold for elevations and a predetermined area threshold for depressions is provided.

7. The apparatus according to claim 3, wherein the examiner is arranged to determine a proportional part of adjacent pixels for a potentially quality-affecting range, which comprises a variation which is in its magnitude larger or equal to the predetermined variation threshold value, and wherein the examiner is further arranged to compare the proportional part to a predetermined edge threshold value, wherein potentially quality-affecting regions with a proportional part larger than the edge threshold value are classified as not being quality-affecting.

8. The apparatus according to claim 3, wherein the examiner is further arranged to compare potentially quality-affecting regions to a predetermined height threshold value to classify the regions whose height is smaller than the predetermined height threshold value as not being quality-affecting regions.

9. The apparatus according to claim 3, wherein the examiner is arranged to calculate the areas of potentially quality-affecting regions and to classify the potentially quality-affecting regions as quality-affecting regions whose area is larger than a predetermined area threshold value.

10. The apparatus according to claim 1, wherein the surface is torus-shaped and comprises a doming and, if applicable, a side wobble, wherein the generator comprises;

a three-dimensional generator for generating a three-dimensional representation of the surface;

a provider for providing a reference representation of the surface, wherein the reference representation reflects the surface without the structure and the unevenness; and

a subtracter for subtracting the reference representation from the three-dimensional representation to obtain a planar height representation of the surface of the body.

11. The apparatus according to claim 4, wherein the provider is arranged to perform a long-range non-linear filtering of a three-dimensional representation of the body.

12. The apparatus according to claim 11, wherein the provider is arranged to eliminate, in an iteration, the potentially quality-affecting regions detected, by the detector, from the three-dimensional representation of the object, to obtain an incomplete three-dimensional representation and to interpolate the incomplete three-dimensional representation or to fit the same by an analytical function to obtain the reference representation of the surface.

13. The apparatus according to claim 1, wherein the height representation is a planar height representation.

14. The apparatus according to claim 1, wherein the height representation is a contour line of a track on the surface and wherein a potentially quality-affecting region is a section of the contour line.

15. The apparatus according to claim 1, therein the body is a vehicle tire, the structure comprises an inscription on the tire and the substantially edge-free unevenness includes a bulge or a constriction.

16. The apparatus according to claim 1, wherein the generator is further arranged to eliminate generated pixel artifacts in an image of the surface.

17. A method for quality testing a body having a surface comprising a structure bounded by edges and a substantially edge-free unevenness, wherein the structure does not constitute any quality impairment, and wherein the unevenness constitutes a potential quality impairment, comprising the following steps:

generating a height representation of the surface, wherein the height representation of the surface includes the structure and the unevenness;

calculating a variation representation from the height representation, wherein the variation representation includes variations of the height representation, so that at a boundary of the structure a high variation is obtained, wherein at a boundary of the unevenness a low variation is obtained; and

detecting regions of the height representation comprising a variation whose magnitude is smaller than a predetermined variation threshold value, wherein the variation threshold value is lower than the high variation and greater than the low variation, so that potentially quality-affecting regions are obtained.