Use of Line-scan Cameras for Monitoring/Detection of Tire ...

Use of Line-scan Cameras forMonitoring/Detection of

Tire Fatigue Cracks

• Pietro Salvini – University of Rome Tor Vergata

• Alessandro Oliva – Bridgestone Technical Center Europe S.p.A

• Roberto Bocchini – University of Rome Tor Vergata

• Background: Indoor Testing in Tire Industry

• Testing and Inspecting Tire for Durability Performace

• Computer Vision techniques based on Linear Camera

• Software Development: Requirement Definition

Pre-processing

Automatic Crack Detection

Use and Distribution

• Results: Pre-processing

Automatic Crack Detection

• Conclusion and Forward Plan

Summary

Tire Testing is as old as Tire itself.

Since from its early stage, Tire Industry had the need to test its (experimental) product before release to the market.

Background: Indoor Testing in Tire Industry

source: http://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpapert318.pdf

Year Test Purpose Test Output External Input

1940s Endurance Mileage

1960sHigh Speed

EnduranceSpeed

1980sDynamic

Measurement

Force & Moment

metrics

2000s Noise & VibrationRide Comfort

metrics

today Tire labelling RR, noise

Evolution of Tire Testing

https://www.google.it/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiOxsDo_q7MAhUEWBQKHQFFA50QjRwIBw&url=https://thenounproject.com/term/factory/321903&bvm=bv.120551593,d.d24&psig=AFQjCNF590ZIYH-VCfiUklxte7iO4EjbEg&ust=1461852418512398













1960sHigh Speed

EnduranceSpeed

1980sDynamic

Measurement

Force & Moment

metrics


metrics


















1960sHigh Speed

EnduranceSpeed

1980sDynamic

Measurement

Force & Moment

metrics


metrics





source: http://www.nhtsa.gov/staticfiles/safercar/pdf/PneumaticTire_HS-810-561.pdf














1960sHigh Speed

EnduranceSpeed

1980sDynamic

Measurement

Force & Moment

metrics


metrics



source: http://www.nhtsa.gov/staticfiles/safercar/pdf/PneumaticTire_HS-810-561.pdf
















1960sHigh Speed

EnduranceSpeed

1980sDynamic

Measurement

Force & Moment

metrics


metrics



source: http://www.etrma.org/tyres/tyre-labelling













Despite new Testing Technologies, Endurance has kept a key role for:

- it is a safety-related item

- validating new Tire Compounds and Constructions

- enhances accuracy of FEM model

- …

Testing Tires for Durability Performance

Durability

Luminosity

Observable

Factors

Appearance

(dark area)

Feature

Crack Finding

Macro

Visual

Inspection

standard

Inspection Tools

Performance

Target

Judgement:

- Mileage

- Failure mode

Despite new Testing Technologies, Endurance has kept a key role for:

- it is a safety-related item

- validating new Tire Compounds and Constructions

- enhances accuracy of FEM model

- …

Inspecting Tires during Durability Test

Durability

Luminosity

Observable

Factors

Appearance

(dark area)

Feature

Crack Finding

Macro

Visual

Inspection

Performance

Target

Judgement:

- Mileage

- Failure mode

Visual

Inspection

Inspection Tools

Computer

Vision

new

Computer Vision techniques based on Linear Camera

1 picture

1 tire rev

Linear Camera

Database

Expected

Benefit

MATLAB has allowed to implement and manage items

Cost effective

solution

New approach to

Tire Inspection

Increased Frequency

of Inspection

Availability of collateral information: Crack Mechanism, Propagation Time, …

Computer Vision techniques based on Linear Camera

LED line light

Line-scan camera

Connection cable

Frame grabber

Software

• Real-time slow-motion on display

• Acquire images at regular time intervals

• Process images to obtain a consistent database

• Automatic crack detection

• Send alert

• Safety: avoiding risks related to the visual inspection.

• REQUIREMENT 1: show a continuous real-time slow-motion of both sidewalls on display,by the images received from cameras.

Software Development: Requirements Definition

Remote Visual Inspection

• Assistance for crack detection: collecting images for analysis.

• REQUIREMENT 2: acquire images of both sidewalls, saving samples at regular timeintervals.


Data Acquisition


• Assistance for crack detection: pre-processing of collected images.

• REQUIREMENT 3: process stored images to obtain a database of consistent images, withsame dimensions, edges and starting point.

Database Management

• Assistance for crack detection: automatic detection of cracks.

• REQUIREMENT 4: automatic detection of cracks, at the earliest possible stage, while thetest is running.


Continuous on-line Image Processing

• Assistance for crack detection: take prompt action.

• REQUIREMENT 5: send an alert e-mail.


Continuous Monitoring and Alert System

• Rotation

Software Development: Pre-processing

Main functions and tools

• imrotate

• detectHarrisFeatures

• Cut



• std

• corr

• findpeaks

• Indexing

• Resize



• imresize

• Brightness adjustment



• reshape

• hist

• Symbolic Math Toolbox


Rotation• imrotate


Cut

• std

• corr

• findpeaks

• Indexing

Resize • imresize

Brightness adjustment

• reshape

• hist

• Symbolic Math Toolbox


• Reference image

• Image with a crack

Results: Pre-processing

• Harris corners detection

Software Development: Automatic Crack Detection



• Indexing

• Selection by pixel intensities



• im2bw

• regionprops

• bwconncomp

• bwareaopen


Harris corners detection • detectHarrisFeatures

Suspicious areas selection • Indexing

Selection by pixel intensities

• im2bw

• regionprops

• bwconncomp

• bwareaopen



E-mail sending • sendmail

Custom Graphical User Interface• GUI Development Environment

• Programmatic workflow

Exe file creation • Deployment Tool

Software Development: Use and distribution

Results: Automatic Crack Detection

~15mm ~4mm

Crack at Advanced Stage Crack at Early Stage

Detection of Cracks and Alert email at early stage is under debugging

Item Dimension

Dimensions1993mm x

126.8mm

Major Axis

Length3.2mm

Minor Axis

Length0.65mm

Orientation

Angle-23.9°

Area 1.63 mm2

raw images

processed images

raw images

processed images

Final Target

Conclusion and Forward Plan

- A new tool has been implemented to assist Tire Inspection during Indoor Tire Testing.

- The new tool is based on Computer Vision Technology.

- In the above framework, using MATLAB has allowed to successfully:

a) handle sets of raw images;

b) manage a consistent database of images, w/ same dimensions, edges and starting point;

c) implement a user-friendly GUI for software set-up;

d) implement crack detection strategies by image processing and consecutive comparison;

e) implement alert system for notifying early cracks.

- The End-User is put in condition to:

1) remotely see a crack starting and developing w/o stop testing;

2) better plan daily activities;

3) decide wether stop testing durability performance and go for other non-destructive investigation

Forward PlanDebug and release new software for detecting and notifying cracks at early stage (~4mm length).

Use of Line-scan Cameras for Monitoring/Detection of Tire ...

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