electronic imaging fundamentals: pressure die castings

Electronic Imaging

Fundamentals:

Pressure Die Castings

“..any sufficiently advanced technology is indistinguishable from magic.” Arthur C. Clark

August 2008

Background: Quality control is of major importance in the pressure die casting industry. Inspection of the item by human inspectors prone to short and long term variations.

An automated casting inspection system using cameras is proposed.

Requirement: Provide image analysis technology linked to a camera to measure size / thickness / angle / shape and other parameters as required.

REJECT when measurement obtained is outside SPEC, allowing casting to be rejected.

Why do Image Analysis?

Better Definition of Contrasting Areas Improved Precision/Accuracy in Measurements Reproducibility of Results Higher Throughput than Manual Methods

A Word About Our Eyes

Eyes are very good contrast adjusters, but not good for distinguishing subtle variations in color

Eyes can discern about 30 continuous levels of gray or color in a field of view

Eyes are not good judges of distance Eyes cannot accurately reproduce

measurements

Which is BIGGER / LONGER???

Electronic Imaging Fundamentals

Acquire

Process

Identify

Analyze

Report

Arguably, the most important aspect of all Proper setup of imaging apparatus is vital Obtain maximum contrast and dynamic range Reduce “noise” and other unwanted artifacts Uniform lighting (light) Product presentation (right way up) Resolution (CCTV VS DIGITAL)

Acquiring the Image

Slide 9

www.I-Cube.co.za

Lens

Image sensor Digitizing

Pre-processing

Timing Interface

PLC

Cat-5e Ethernet cable up to 100 m

Local I/Os:- Trigger input- Results output

Illumination control

Image ProcessingIn PC

Illumination

(Lens Iris Video)

Power

Acquire

Calibration

Thresholding an Image Select appropriate morphometric characteristics

Identify regions of interest to analyse

Mask regions

ColourSizeShape Intensity

DATA

Recorded Rejected

20080814_18-25- 0.514 20080814_18-25- 0.514 20080814_18-25- 0.523 20080814_18-24- 0.862 20080814_18-24- 0.504 20080814_18-24- 0.407 20080814_18-24- 0.162 20080814_18-23- 1.17 20080814_18-21- 0.281 20080814_18-21- 1.806 20080814_18-21- 0.169 20080814_18-20- 0.626 20080814_18-20- 0.969 20080814_18-19- 1.121 20080814_18-18- 0.957

NEXT STEP: Consulting @ R 7 500.00 to explore:

- CCTV vs DIGITAL (accuracy)

- Measurement process (11 measurements)

- Image setup

- Equipment required

- Input Trigger / rejection

- Image / data storage