Tyre Inspection System Using Laser Triangulation Shift Compensation

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Solution Overview

Problem

In the field of tyre quality control, there is a need for efficient and cost-effective methods to inspect the inner and outer surfaces of tyres for defects using optical acquisition and processing of digital images, particularly in a production line setting where time and resource constraints are significant.

Innovation Solution

Combining 2D and 3D image acquisition systems in a single device mounted on a robotized arm, utilizing a linear camera for 2D imaging and a matrix camera with laser triangulation for 3D imaging, and dynamically calculating the shift of the acquisition point to identify and process only the sub-portion of the image containing the reflected laser line, optimizing processing time and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If 2D and 3D image acquisition systems are combined in a single device mounted on a robotized arm, then measurement precision and detection accuracy are improved, but device complexity increases

Engineering Contradiction:
Improvedetection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines 2D linear camera and 3D matrix camera with laser triangulation into a single inspection device mounted on a robotized arm. This merging of multiple acquisition systems allows simultaneous capture of both 2D and 3D images of the tyre surface, improving measurement precision and detection accuracy while sharing common mechanical support and control infrastructure

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single inspection device performs multiple functions by integrating both 2D image acquisition (for surface defect detection) and 3D image acquisition (for elevation and shape analysis). The robotized arm provides universal positioning capability, allowing the device to inspect different areas of the tyre by moving to various coordinates, making the system multi-functional rather than requiring separate dedicated devices

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If the entire matrix image is processed to identify the reflected laser line, then measurement precision is improved, but processing time increases

Engineering Contradiction:
Improveposition accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent divides the matrix image processing into segments by first identifying only the region containing the reflected laser line, then processing only that specific sub-portion. This segmentation approach avoids processing the entire matrix image, significantly reducing processing time while maintaining measurement precision through focused analysis of the relevant area

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the reflected laser line from the entire matrix image by using the known geometry of the laser projection and camera position to calculate where the laser line should appear. Once extracted or identified, only this specific line and its surrounding area are processed for elevation measurement, separating the essential information from the redundant parts of the image

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If high-resolution imaging is maintained throughout the entire image, then measurement precision is improved, but processing time and computational resources increase

Engineering Contradiction:
ImproveresolutionVSAvoidprocessing speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies high-resolution processing only locally to the sub-portion of the matrix image containing the reflected laser line, rather than processing the entire image at full resolution. This local quality approach maintains measurement precision where it is needed (at the laser line location for elevation measurement) while reducing overall processing time and computational resource requirements for the rest of the image

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables rapid and accurate detection of defects on tyre surfaces, including material lacks or excesses, bubbles, cuts, and other features, while minimizing processing time and maintaining high resolution, thus facilitating direct implementation in production lines.

Implementation Method 1

a laser source (13) able to emit a linear laser beam (14)

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

containing a reflected laser line (61)

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

a first acquisition system (2) for acquiring two-dimensional images of a surface of a tyre (3)

Methodology Applied
Scientific EffectOptical imaging: Lens

Implementation Method 4

a second acquisition system (10) for acquiring three-dimensional images of a surface of the tyre (3)

Methodology Applied
Scientific EffectOptical triangulation: Parallax

Data Source

PatentEP3639002B1Method for checking tyres
Publication Date: 2022.08.03 PIRELLI TYRE SPA
  • EP3639002B1 patent drawingFigure 1
  • EP3639002B1 patent drawingFigure 2~3
  • EP3639002B1 patent drawingFigure 4

AI summary

It is described a method for checking tyres, wherein it is provided : predisposing a tyre (3) to be checked having a rotation axis (20) and a surface; determining a shift (S) along an acquisition direction (5, 32) between an acquisition point (51) on the surface lying on a first radial plane and a position (42) occupied by the acquisition point (51) following a rotation of the tyre about the rotation axis (20), the position (42) lying on a second plane parallel to the first radial plane; projecting a linear laser beam on a linear portion of surface of the tyre (3), where the linear laser beam propagates on the second plane with a propagation direction (14) that is parallel to the acquisition direction (32); acquiring a matrix image (60) of a matrix portion of surface of the tyre (3) containing the linear portion of surface, where the matrix image contains a laser line reflected by the linear portion of surface; determining a sub-portion (63) of the matrix image (60) as a function of the determined shift (S), where the sub-portion of the matrix image contains the reflected laser line; processing the sub-portion (63) of the matrix image (60) for determining an elevation profile of the linear portion of surface.