Method for checking tyres for vehicle wheels

Patent metadata

Field	Value
Publication number	US-10900774-B2
Application number	US-201716320465-A
Country	US
Kind code	B2
Filing date	Jul 25, 2017
Priority date	Jul 26, 2016
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

A method for checking a tyre for vehicle wheels in a checking station. The checking station includes a background with a support surface lying on a plane perpendicular to a reference axis, an image acquisition apparatus to acquire an image of the tyre arranged with a first outer lateral surface in contact with the support surface and a second outer lateral surface facing the image acquisition apparatus, an illumination system and a computer for generating a working image from the acquired image. The image acquisition apparatus, the illumination system and of the background are arranged to generate a contrast, in the working image, between the entire second outer lateral surface of the tyre and an area circumferentially surrounding the tyre.

First claim

The invention claimed is:

1. A method for checking a tyre for vehicle wheels in a checking station, the checking station comprising a background with a support surface lying on a plane perpendicular to a reference axis, an image acquisition apparatus to acquire at least one image of the tyre arranged with a first outer lateral surface in contact with the support surface and a second outer lateral surface facing the image acquisition apparatus, an illumination system and a computer adapted to generate a working image from the at least one acquired image of the tyre, the method comprising:
arranging the image acquisition apparatus, the illumination system and the background to generate a contrast, in the working image, between at least an entire second outer lateral surface of the tyre and an area circumferentially surrounding the tyre, the circumferentially surrounding area corresponding to at least one part of the background, including at least one part of the support surface;
supplying the tyre to the checking station with the first outer lateral surface in contact with the support surface, in a predefined position on the support surface;
acquiring, with the image acquisition apparatus, the at least one image of the tyre;
during the acquisition, illuminating the tyre with the illumination system, illuminating at least the second outer lateral surface of the tyre and the circumferentially surrounding area;
generating from the at least one acquired image of the tyre, with the computer, the working image comprising the second outer lateral surface of the tyre and the circumferentially surrounding area; and
processing, with the computer, the working image, to perform at least one checking procedure of the tyre wherein the second outer lateral surface of the tyre is distinguished from the circumferentially surrounding area by means of the contrast,
wherein
the illumination of the tyre is carried out by illuminating, in a single step or in multiple successive illumination steps, at least the entire second outer lateral surface of the tyre according to an angularly uniform illumination with respect to the reference axis,
the acquisition of the at least one image of the tyre and the illumination of the tyre are carried out with the tyre in a stationary condition, and
the contrast is obtained in terms of color or grey level, among pixels in the working image that correspond to the at least the entire second outer lateral surface of the tyre and among pixels in the working image that correspond to the circumferentially surrounding area.

2. The method according to claim 1 , wherein, in case of color contrast, the image acquisition apparatus is arranged with a color camera.

3. The method according to claim 2 , wherein, the at least one part of background to which the circumferentially surrounding area corresponds is arranged in at least one color different from black and grey.

4. The method according to claim 1 , wherein, in case of grey level contrast, the image acquisition apparatus is arranged with a black and white camera.

5. The method according to claim 4 , wherein, the illumination system is arranged with a first illumination assembly, adapted to illuminate the at least the second outer lateral surface of the tyre according to an angularly uniform illumination, and a second illumination assembly adapted to illuminate the circumferentially surrounding area.

6. The method according to claim 5 , wherein, the illumination of the tyre with the illumination system comprises the illumination of at least the second outer lateral surface of the tyre with the first illumination assembly and the illumination of the circumferentially surrounding area with the second illumination assembly, the illumination of at least the second outer lateral surface of the tyre and the illumination of the circumferentially surrounding area being carried out in sequence, one after the other.

7. The method according to claim 6 , wherein, the acquisition, with the image acquisition apparatus, of the at least one image of the tyre, comprises the acquisition of at least one image during the illumination of the at least second outer lateral surface of the tyre and the acquisition of at least one image during the illumination of the circumferentially surrounding area.

8. The method according to claim 7 , wherein, in the generation of the working image, the at least one image acquired during the illumination of the circumferentially surrounding area is subjected to a filtering operation adapted to increase and make uniform the grey level of the pixels of the at least one image that are related to the circumferentially surrounding area.

9. The method according to claim 8 , wherein the first illumination assembly comprises a plurality of illumination devices, the illumination of at least the second outer lateral surface of the tyre being carried out by activating all the illumination devices of the plurality, or subgroups thereof, in sequence.

10. The method according to claim 9 , wherein the acquisition, with the image acquisition apparatus, of the at least one image of the tyre, comprises the acquisition of at least one image during each activation of the illumination devices of the first illumination assembly.

11. The method according to claim 10 , wherein the generation of the working image comprises combination of the images acquired during sequential illumination of at least the second outer lateral surface of the tyre and of the circumferentially surrounding area.

12. The method according to claim 11 , wherein the at least one procedure for checking the tyre comprises an identification procedure for identifying a rotation axis of the tyre.

13. The method according to claim 12 , wherein the at least one procedure for checking the tyre comprises a centering operation adapted to align the rotation axis of the tyre, identified with the identification procedure, with the reference axis.

14. The method according to claim 13 , wherein the centering operation comprises detection of a deviation, on a plane of the support surface, between the reference axis and the rotation axis of the tyre and, in presence of the deviation, movement of the tyre on the plane, with respect to the reference axis, until substantially aligning the rotation axis of the tyre with the reference axis.

15. The method according to claim 14 , wherein, supplying the tyre in the predefined position on the support surface comprises a pre-centering operation, along a predetermined direction in the plane of the support surface, adapted to guarantee a deviation, along the predetermined direction, between the rotation axis of the tyre and the reference axis, less than or equal to a predetermined threshold.

16. The method according to claim 15 , wherein, the support surface defines the support surface of a rotating table having a rotation axis substantially coinciding with the reference axis.

17. The method according to claim 16 , wherein the at least one procedure for checking the tyre comprises a centering operation adapted to align the rotation axis of the tyre with the rotation axis of the rotating table.

18. The method according to claim 17 , wherein the centering operation is carried out with a stationary rotating table and, after the centering operation, the rotating table is rotated together with the tyre around the rotation axis of the rotating table, and further checking procedures are carried out on the tyre while the rotating table and the tyre are in rotation.

Assignees

• Pirelli

Inventors

• Boffa Vincenzo
• Tersi Luca
• Ballardini Valeriano

Classifications

• G01M17/02 Primary

  Tyres · CPC title

• G01B11/24

  for measuring contours or curvatures · CPC title

• G01M17/027 Primary

  using light, e.g. infrared, ultraviolet or holographic techniques · CPC title

• G01B11/2408 Primary

  for measuring roundness · CPC title