Method for tire tread depth modeling and image annotation

Patent metadata

Field	Value
Publication number	US-9805697-B1
Application number	US-201313835241-A
Country	US
Kind code	B1
Filing date	Mar 15, 2013
Priority date	Jun 1, 2012
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

A vehicle service system having a means for acquiring images of a three-dimensional region of a vehicle wheel assembly tire tread surface. The vehicle service system is configured to process the acquired images to produce a collection of data points corresponding to the spatial position of surface points in the region from which tire tread wear characteristics are identified. The acquired images are further utilized to provide both a graphical and a numerical display to an operator, with the numerical display linked to specifically annotated or indexed points or windows within the graphical display, thereby enabling an operator to quickly identify specific focus points or regions on the tire surface which have been measured at the numerically identified tread depths.

First claim

The invention claimed is:

1. A machine vision vehicle service system having a processing unit configured with a set of software instructions, and at least one imaging system operatively coupled to the processing unit, the improvement comprising:
wherein said imaging system is disposed to view a surface region of a vehicle wheel assembly, said surface region including a three-dimensional portion of a tire tread surface on an associated vehicle wheel assembly;
wherein the processing unit is further configured to determine at least one vehicle wheel parameter for said vehicle wheel assembly from a generated point cloud of data points representative of at least the three-dimensional portion of the tire tread surface developed by the processing unit from images of said surface region acquired by said imaging system; and
wherein said at least one vehicle wheel parameter includes a measure of tire tread depth determined from a comparison between said point cloud data points fitted to a tire tread cross-section curve representative of a tire tread outer surface within said surface region and a tire tread cross-section curve representative of a tire tread valley floor surface within said surface region.

2. The machine vision vehicle service system of claim 1 wherein said generated point cloud of data points of said tire tread surface is represented in a cylindrical coordinate system with an axis of said cylindrical coordinate system representative of an estimated wheel axis.

3. The machine vision vehicle service system of claim 2 wherein said processing unit is configured to estimate a tire tread depth measurement over said three-dimensional portion of tire tread surface by processing said data points in said cylindrical coordinate system to collapse said points into a single plane of the cylindrical coordinate system which is longitudinally perpendicular to said estimated wheel axis.

4. The machine vision vehicle service system of claim 3 further including the step of filtering said collapsed data points by generating a histogram of point coordinates collapsed into said single plane of said cylindrical coordinate system;
wherein a radial direction maximum peak in said generated histogram is representative of data points on a tire tread outer surface, said outer surface data points within said single plane defining said curve representative of a contour of the tire tread outermost surfaces; and
wherein a radial direction minimum peak in said generated histogram is representative of data points on a tire tread recessed surface, said recessed surface data points within said single plane defining said curve representative of said tire tread valley floor surfaces.

5. The machine vision vehicle service system of claim 1 further including a rotating shaft upon which said vehicle wheel assembly is mounted for controlled rotation about an axis; and
wherein said surface region extends circumferentially about said vehicle wheel assembly.

6. The machine vision vehicle service system of claim 1 wherein said measure of tire tread depth is associated with a tire shoulder region of said vehicle wheel assembly.

7. A method for measuring a tread depth within a region on the surface of a wheel assembly tire, said region having an axial width and an arcuate length along a circumference of the wheel assembly, comprising:
acquiring image data representative of at least a portion of the tire surface including said region;
processing said acquired image data to generate a two-dimensional representation of said region, said two-dimensional representation denoting both an outer surface of the tire tread and a lower surface of the tire tread over an axial width equal to the axial width of said region; and
wherein a measure of tread depth at a selected location within said region on said surface of said wheel assembly tire is determined by a comparison of said denoted outer surface within said two-dimensional representation at an axial position of said selected location along said axial width of said region with said denoted lower surface within said two-dimensional representation at said axial position of said selected location along said axial width of said region.

8. The method of claim 7 wherein said step of processing further includes:
generating a point cloud of discrete data points in a three-dimensional coordinate system about an axis of rotation for the wheel assembly, said point cloud representative of points in said region on said surface of said wheel assembly tire;
processing said point cloud of discrete data points to individually rotate each of said data points about said axis of rotation into a common plane; and
evaluating histogram peaks of radial distances of said data points from said axis of rotation within said common plane to establish said representation denoting said outer surface and said lower surface of the tire tread within said common plane.

9. The method of claim 7 further including the step of utilizing said two-dimensional representation to compare said denoted outer surface of the tire tread within said region on said surface of said wheel assembly tire with the denoted lower surface of the tire tread within said region on said surface of said wheel assembly tire to evaluate a symmetry of the tire across said axial width of said region on said surface of said wheel assembly tire.

10. The method of claim 7 wherein said selected location within said region on said surface of said wheel assembly tire is associated with a shoulder region of said wheel assembly tire.

11. A method for presenting a visual display of tire tread depth information associated with a vehicle wheel assembly, comprising:
acquiring tire tread depth measurement data from a plurality of points within a tire surface region;
processing said acquired tire tread depth measurement data to generate at least a two-dimensional image of said tire surface region which is representative of tire tread depth at said plurality of points within said tire surface region for display to an operator;
displaying a plurality of numerical values representative of tire tread depth measurements in association with said two-dimensional image; and
visually indicating an association between each of said displayed numerical values and associated tire tread depth measurement points at locations within said two-dimensional image.

12. The method of claim 11 wherein said two-dimensional image of said tire surface region represents said tire tread depth at said plurality of points with an array of colors, wherein each color within said array of colors corresponds to a unique measure of tire tread depth.

13. The method of claim 11 wherein said at least one numerical value is representative of a tire tread depth measurement at a specific point within said two dimensional image; and
wherein said step of visually indicating said association includes providing a visual connection between said displayed numerical value and said specific point.

14. The method of claim 13 further including the step of selectively positioning said specific point within said two dimensional image.

15. The method of claim 11 wherein said at least one numerical value is representative of an average tire tread depth over measurement points within a window denoting a selected region within said two dimensional image; and
wherein said step of visually indicating said association includes providing a visual connection between said displayed numerical value and said window within said two-dimensional image.

16. The method of claim 15 further including the step of visually i

Assignees

• Hunter Eng Co

Inventors

• Dorrance Daniel R
• Colarelli Iii Nicholas J
• Strege Timothy A

Classifications

• G09G5/40 Primary

  characterised by the way in which both a pattern determined by character code and another pattern are displayed simultaneously, or either pattern is displayed selectively, e.g. with character code memory and APA, i.e. all-points-addressable, memory · CPC title

• B60C99/006 Primary

  Computer aided tyre design or simulation · CPC title

• G06V10/44

  Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components · CPC title

• H04N13/0203

  Electricity · mapped topic

• G06V20/647

  by matching two-dimensional images to three-dimensional objects · CPC title