2018 intro machine_vision-webinar (1)

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INTRODUCTION TO MACHINE VISION
Thibaut van Baer | February 2018

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Agenda
▪ What is machine vision?
▪ Why use machine vision?
▪ Machine vision applications
▪ Types of machine vision systems
▪ Vision system components
▪ Machine vision terms
▪ Improving vision system performance
▪ Summary
▪ Q&A

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What is machine vision?
The camera lens and sensor
capture images…
Cognex advanced vision tools
interpret what’s being seen

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Proprietary Box
Embedded
Boards
Modular
Vision
Barcode
Readers
PC Vision
Vision
Sensors
1982 Today
3D Displacement
Sensors
Evolution of machine
vision

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Machine vision systems:
1. Analyze images
2. Makes decisions and returns results about each image
Simple examples
The center tab on this bracket is
37.255 mm wide
Good Oil Filter:
All holes are
open
Bad Oil Filter:
Some holes
are blocked

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Image analysis
The primary purpose of machine vision is image analysis
Image
Decision
Answer
Location

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Where is machine vision used?
Automotive
Industry
Graphic Arts/
Packaging
Consumer
Products
Semiconductor
Industry
Shipping
Transportation
Electronics
Medical
Pharmaceutical
Food Packaging
Industry

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▪ Automate manufacturing
processes
▪ Improve product quality
▪ Protect brand image
▪ Reduce operational costs
Why is machine vision used?
▪ Overcome inefficient manual
inspection processes
▪ Increase manufacturing throughput
▪ Reduce material waste
▪ Minimize the risk of recalls

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Critical for achieving strategic goals
▪ High speed production lines
▪ Clean room environments
▪ Hazardous environments
▪ Microscopic inspection
▪ Closed-loop process control
▪ Robot guidance
▪ Precise non-contact
measurement

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Manufacturing Goal Machine Vision Applications
Improved product quality Inspection, measurement, gauging, and
assembly verification
Increased productivity Repetitive tasks done manually are
automated with machine vision
Production flexibility and
less machine downtime
Automatic product changeovers
Increased manufacturing
throughput
High-speed inspection keeps up with the
fastest production lines
Reduce manufacturing
waste
Detecting defects earlier in the process
prevents adding value to defective
products
Benefits of machine vision

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MACHINE VISION APPLICATIONS

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What does machine vision do?
GUIDE INSPECT GAUGE IDENTIFY
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Determines part position (x, y, and angle)
Automates handling of parts for machines:
▪Alignment & Placement
▪2D & 3D Picking
▪Eliminates need for fixturing &
improves robot flexibility
Vision tool alignment, fixturing
▪Locate at least one feature on a part for
the purpose of calculating the (x, y)
position and rotation of the part to
position other vision tools precisely
Guidance

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Trained Image Out of focus
Uneven Lighting
Occlusions
Confusing Background
Rotation and Scale Changes
Geometric pattern matching

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Appearance Changes
Part location challenges

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Part location challenges
Variation in part appearance
1

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Correct location
▪Orientation
▪Skew
Quality
▪Defect Detection
▪Surface Inspection
▪Contaminants
Completeness
▪Fill Level
▪Feature Presence
▪Counting
▪Assembly Verification
Inspection

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Precise dimensioning
▪ Automated metrology and
data recording
Ensures tolerances
▪ Diameters
▪ Gaps
▪ Bushings
▪ Threads, etc.
Gauging

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Read Codes
▪ Printed 1-D Barcodes & 2-D Matrix
▪ Direct Part Mark
Read Characters
▪ OCR / OCV
Recognize Objects
▪ Based on color, shape, or size
Identification

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MACHINE VISION PRINCIPLE

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1D machine vision
▪ 100% continuous web
inspection and classification
▪ Uses line-scan cameras
▪ Materials inspected include:
Metals, non-wovens
Plastics, Paper

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1. Unwrap cylindrical objects for
inspection
2. Add vision to space-constrained
environments
3. Meet high-resolution inspection
requirements
4. Inspect objects in continuous
motion
Four reasons to use line scan

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2D machine vision – area scan

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3D Machine Vision

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Profiler principle of operation

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Displacement sensor

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VISION SYSTEMS AND SENSORS

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COGNEX VISION SENSOR
Compact, modular
body design fits into
tight spaces
Field changeable, high power,
diffuse illumination
Powerful, proven In-Sight®
vision tools for reliable
inspection performance
Field changeable
lenses and filters
for optimal image
quality
Step-by-step setup
with EasyBuilder®

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▪ Industry-leading image acquisition and optical character
recognition
▪ Powerful and precise pattern matching algorithms
▪ Most reliable and flexible inspection systems
Cognex 2D Vision

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Cognex 3D Vision
▪ 3D laser displacement sensors provide three dimensional inspection of
products to optimize quality
▪ Measure height, volume or tilt with cross section and plane fitting tools –
regardless of contrast or light variations
▪ Expanded range of 3D sensors, factory calibrated to deliver real-world values

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SYSTEM COMPONENTS

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Key parts of a vision system
Light Source
Vision System
Vision Software
I/O Comm.
Camera
Lens
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Inputs/Outputs: switches, PLCs, robots, lights
Communication

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Putting it all together
Camera
Monitor
Operator Pointing Device
(Trackball, Mouse, Touchscreen)
Parts
Light Source
Vision System
Output:
•Serial
•Parallel
•ISA, PCI, VME bus
Input:
•Serial
•Parallel
•ISA, PCI, VME busa
Lens

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How the system works
1. Part arrives at inspection station
5. Software algorithms running on vision system
performs image processing and/or image analysis
on acquired image
6. Vision system sends signal along a discrete output
line which activates a diverter if the part is bad
7. Operator can view rejected parts and ongoing statistics on display,
and can take system off-line if necessary
2. Sensor detects part and sends a trigger to the vision system
3. Strobe is flashed to
illuminate part 4. Vision System acquires the image from the sensor.
FAIL

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Machine vision algorithms
All within just one to tens of milliseconds!
Algorithms used by Vision Tools transform raw numbers into
useful higher level features …
- Raw numbers turned into edges, colors, characters, and
other characteristics
… then makes decisions
- Returns answers such as position, similarity, distance,
presence, quality

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TERMINOLOGY

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Vision definitions
Field of View (FOV)
▪ The part which can be
seen by the machine
vision system at one
moment.
▪ The field of view
depends on the lens of
the system and the
working distance
between object and
camera.
5” x 7”

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Field of view
What is my field of view?
3”
4”
8”
15”

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Working distance and resolution
Working Distance (WD)
▪Distance between the
FRONT of the lens and the
target
Resolution
▪The minimum feature size of
the object under inspection.
10”

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Correlation working distance/FOV


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Depth of field
Depth of Field (DOF)
▪ The distance in front of and
behind the object which
appears to be in focus
3”
More DOF with a small aperture
(high f/number) than with a large
aperture (low f/number)

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SYSTEM COMPONENTS

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Different lens … same image?
▪ Lighting
▪ Depth of field
▪ Working distance
▪ Line speed
▪ Exposure time
▪ Aperture
▪ Budget

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Lighting techniques
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Bright Field
Dark Field
Back Lighting
Diffuse Dome
Axial Diffuse
Light can be structured in different ways. Angle and direction of the
light determine how the mark and space is seen by the camera.
Structured

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Optics
To learn more about choosing the right optics go to
Cognex.com > Resources > On-Demand Webinars

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Filtering techniques
▪ Control quality and quantity of
light
▪ Block all unwanted
ambient lighting
▪ Pass only the output of
lighting used for inspection
▪ Increase contrast
and resolution
For more on optical filters, go to Cognex.com >
Resources > On-Demand Webinars

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Image pre-processing tools
To learn more about image pre-processing,
go to Cognex.com > Resources > On-Demand
Webinars

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Summary
▪ Make products better, faster, and less expensively
▪ Gauging, Inspection, Guidance, and Identification are
the key applications
▪ Key components are the lens, camera, lighting, vision
software and communications
▪ Learn more about optics, lighting, filters and image pre-
processing to improve system performance
▪ Don’t go it alone…get help from experts!

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QUESTIONS?
Contact.eu@Cognex.com | www.Cognex.com