MACHINE VISION

David Bilodeau13 October 2010

What is Machine Vision?

the use of some form of optical sensor and signal processing to make decisions in an automated work cell.

the most common uses are in quality control (rejection vs. acceptance) and sorting

What is Machine Vision?

What is Machine Vision?

Typical Components

sensor to trigger camera camera (color, B&W) camera interface processor machine vision software output hardware specialized light source (LEDs, large lamps,

IR…)A ‘frame grabber’ converts analog camera input into digital output.

Typical Components

Typical Components

Typical Components

Capabilities/Limitations

won’t talk about specifics since it varies so widely by type of system and application

camera resolution lighting speeds camera can capture or frame

grabber can capture processor and algorithm output response

Review of Technical Paper

Problem - “Currently, most systems perform weld seam inspection after completing the welding process because they are not capable of online inspection. As a result, finished weldments with defects have to be gas cut and welded again, reducing productivity. Moreover, it is challenging to control the weld bead quality without online weld bead profile monitoring, further degrading the weld system’s performance.”

discusses how they set things up, math behind the imaging

discusses the algorithms a little gives examples of what the machine vision ‘saw’

Review of Technical Paper

Standards

“GigE Vision - True Plug and Play Connectivity GigE Vision® is a camera interface standard developed using the Gigabit

Ethernet communication protocol.GigE Vision GigE Vision allows for fast image transfer using low cost standard cables over very long lengths. With GigE Vision, hardware and software from different vendors can interoperate seamlessly over GigE connections.

 GigE Vision is a widely adopted interface, with dozens of leading companies

currently offering hundreds of GigE Vision compliant products. GigE Vision offers many benefits including:

FAST High bandwidth (1000 Mbps) transfers large images quickly in real time

ABUNDANT Uncompromised data transfer up to 100 meters in lengthSTANDARD Low cost CAT5e or CAT6 cables and standard connectorsSCALABLE Highly scalable to the fast growth of EthernetLOW COST Standard hardware and cables allow easy, low cost

integration”(2010 Automated Imaging Association)

Standards

“Camera Link – The Only Real-Time Machine Vision Network Protocol GigE VisionCamera Link®, currently in Version 1.2, is a robust communications link using a

dedicated cable connection and a standardized communications protocol. Camera Link was built for real time, high bandwidth (maximum 6.1 Gbps) parallel communication. It is a well established and proven industry standard, there are hundreds of Camera Link products on the market today. These compliant products are interoperable, providing users with the flexibility to choose the best product for their needs without worrying about compatibility between different manufacturers. Camera Link now has GenICam support for plug and play interoperability

 Camera Link offers many benefits, including: Real-time, high-speed: High bandwidth assures fast transfer of large files with no latency

issues. Easy product interoperability: Camera Link products use the same cable connection.

Compliant cameras and frame grabbers can easily be interchanged using the same cable.

 Lower Cable Prices: Because Camera Link is a widely adopted standard, cables are readily available and competitively priced. Mini Camera Link provides a very small footprint when space is an issue.

 Single Cable Power: Power over Camera Link, PoCL®, allows the camera to be powered by the frame grabber through the single Camera Link cable, which saves space and money.

 Camera Link Lite: Smaller connector supporting base configurations for low cost solutions.”(2010 Automated Imaging Association)

Standards

“EMVA 12881288 defines a unified method to measure, compute and

present specification parameters for cameras and image sensors used for machine vision applications. Application of this standard will benefit users of vision components by avoiding misunderstanding and reducing pre- and post-support cycles.

 The standard is elaborated by a consortium of the industry

leading sensor and camera manufacturers, distributers and component customers and is hosted by the European Machine Vision Association (EMVA). For more information please visit www.standard1288.org.”

(2010 Automated Imaging Association)

Standards

“GenICamTMThe goal of GenICamTM is to provide a generic programming interface for

all kinds of cameras. No matter what interface technology (GigE Vision, Camera Link, 1394 DCAM, USB, etc.) they are using or what features they are implementing, the application programming interface (API) should be always the same.

The GenICam standard consists of multiple modules according to the main tasks to be solved:

  * GenApi: configuring the camera * Standard Feature Naming Convention (SFNC): recommended names

and types for common features * GenTL: transport layer interface, grabbing images The GenICam standard group is hosted by the European Machine Vision

Association (EMVA). For more information please visit www.genicam.org.”

(2010 Automated Imaging Association)

Standards

“Lens Mount Standards by JIIA Lens Mounts for Machine Vision Cameras – Lens Mount SizesLE-002-2008This standard provides the lens mount sizes matched to image sizes

for industrial cameras. Lens Mounts for Machine Vision Cameras – Classification of Images

SizesLE-001-2007This standard provides the classification of image size of lens mounts

industrial cameras. The standards are hosted by the Japan Industrial Imaging Association

(JIIA). Visit www.jiia.org for more information.”(2010 Automated Imaging Association)

Costs

While you could make your own knowing the components… not advised.

sensor to trigger camera – what kind and how? camera (color vs. B&W, continuous or stop motion, high

enough resolution, durability for environmental situation) camera interface (purchase a card for the machine, design

your own?) processor (part of a standard PC but the big issue comes

with the software) machine vision software (which? Some are best for certain

machines, writing one would be nuts!) output hardware (I/O interface to control something) specialized light source (LEDs, large lamps, IR…) frame grabber? (encoder or software based?)

Costs

Full systems usually run around $5000-$20000

IR scanners $89-$1500 based on speed, features, etc.

Can also purchase support packages. Depends on number supported and length of time.

Application Example

Application Example

Vendors

Found over 100 vendors of Machine visions systems, some are general, some specialized.

Cognex – big into barcode scanning Keyence National Instruments Retina Systems Omron AccuSentry Dark Field Technologies Advanced Inspection & Measurement

Vendors – Choosing

http://www.machinevisiononline.org/vision-resources-details.cfm?content_id=1229

References

http://www.cognex.com/Main.aspxhttp://www.keyence.com/products/vision/machine/machine.phphttp://www.ni.com/vision/http://www.machinevisiononline.org/ - central location that

refers to products, standards…http://www.youtube.com/watch?v=O0Tr430zHXohttp://www.youtube.com/watch?v=RhPD_EqSwCcYuan Li; You Fu Li; Qing Lin Wang; De Xu; Min Tan; ,

"Measurement and Defect Detection of the Weld Bead Based on Online Vision Inspection," Instrumentation and Measurement, IEEE Transactions on , vol.59, no.7, pp.1841-1849, July 2010 doi: 10.1109/TIM.2009.2028222 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5288594&isnumber=5482403

Images References

http://www.high-techdigital.com/integration/index.htmhttp://www.cybervolume.com/machine-vision-systems.htmlhttp://zone.ni.com/cms/images/devzone/tut/circuitboard.JPGhttp://zone.ni.com/cms/images/devzone/tut/clamps.JPGhttp://sine.ni.com/cms/images/casestudies/naturenaha.jpg

http://sine.ni.com/cms/images/casestudies/naturenbeng.jpg

http://www.keyence.com/products/vision/machine/cv3000/cv3000_topimage.jpghttp://www.cognex.com/uploadedImages/Products_and_Services/Vision_Systems/In-Sight/In-Sight_without_Sidebar/InSight_Models_Micro.jpg