3D Tire Surface Inspection Using B-Spline Deformation

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Solution Overview

Problem

Current methods for visual inspection of tires during production fail to accurately match the deformable tire surface with its reference surface due to the elastic nature of tire materials, leading to incorrect judgments in conformity assessment.

Innovation Solution

The method involves determining the three-dimensional profile of the tire surface, extracting contours, and using B-spline surfaces to deform the reference surface by modifying control points to minimize distance between contours, allowing for precise superposition and comparison with the inspected surface, including additional steps to refine the matching process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If rigid transformation methods are used to match reference surface with tire surface, then matching simplicity is improved, but matching accuracy deteriorates due to elastic deformation of tire materials

Engineering Contradiction:

Improvematching process complexityVSAvoidsurface matching accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies elastic transformation parameters to the reference surface, allowing it to deform flexibly and adapt to the actual tire surface geometry. This transforms the rigid matching approach into a flexible one that accounts for material elasticity, thereby improving matching accuracy without excessive complexity increase.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic adjustment capabilities by allowing the reference surface to undergo elastic deformation. Instead of fixed rigid transformations, the system dynamically adapts the reference surface shape to match the inspected tire surface, resolving the contradiction between simplicity and accuracy.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the reference surface is treated as a fixed rigid model, then processing speed is improved, but conformity assessment accuracy deteriorates due to ignoring elastic deformations

Engineering Contradiction:

Improveinspection processing speedVSAvoidconformity assessment reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent performs preliminary elastic deformation of the reference surface before comparison with the inspected tire surface. By pre-adapting the reference model to account for expected elastic deformations, the system maintains fast processing speed while improving the reliability of conformity assessment.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If local surface portions are divided for matching, then adaptability to deformations is improved, but processing complexity deteriorates

Engineering Contradiction:

Improveadaptation to tire deformationsVSAvoidprocessing algorithm complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the tire surface into multiple local portions and applies elastic transformations to each segment independently. This segmentation allows the system to adapt to local deformations more effectively while managing processing complexity through modular treatment of surface regions.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If affine transformations with coefficients different from 1 are applied to the reference surface, then shape variation coverage is improved, but matching precision deteriorates due to over-deformation

Engineering Contradiction:

Improveshape variation coverageVSAvoidcontour matching precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies different transformation characteristics to different regions of the reference surface. By making the transformation properties local rather than global, the system can cover various shape variations in different areas while maintaining precise contour matching in each specific region, avoiding the over-deformation problem of uniform affine transformations.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9123112B2Method for the pre-processing of a three-dimensional image of the surface of a tyre for use in the inspection of said surface

Publication Date: 2015.09.01 MICHELIN & CO (CIE GEN DES ESTAB MICHELIN)

AI summary

A method for inspecting a portion of a tire surface involves comparison with an image of a three-dimensional (“3D”) reference surface. The method includes: extracting contours of graphic elements of an image of a 3D profile of a surface to be inspected; transforming the reference surface by establishing a correspondence between the contours of the graphic elements of the surface to be inspected and contours of identical graphic elements of the reference surface using a series of transformations; associating a B-spline surface, which includes control points, with the graphic elements of the transformed reference surface; and deforming the contours of the graphic elements of the reference surface by modifying positions of the control points of the B- spline surface so as to minimize distances between the contours of the graphic elements of the reference surface and the contours of the graphic elements of the surface to be inspected corresponding thereto.