NIWeek Vision Summit August 2-3, 2011 Austin, Texas

1. NIWeek Vision SummitAugust 2-3, 2011 Austin, Texas www.ni.com/niweek/summit_vision

2. NIWeek Vision SummitAugust 2–3, 2011 Austin, Texas Breaking New Ground with Vision Inspection Systems Dr. Dan Milkie Senior Developer Coleman Technologies, Inc.

3. What if there’s no existing solution? • Prototyping tips • Planning guide • Implementation • Imaging algorithms • Finding small defects • 3D laser triangulation • Final lessons

4. About us • 16 year National Instruments Alliance Partner • Basler Vision System Integrator • NI Certified Developers & NI Professional Instructors • Advanced engineering & science degrees

5. Vision Applications Industrial • Dinnerware defect detection system • Dinnerware color pattern inspection system • Robotic seed germination classifier • High-speed seed counting system • Laser drilling inspection • Thin film defect identification • Mirror defect detection • PCB contact pad inspection system • Color tablet tracking • Particle size analysis (powders) • Particle size analysis (liquid suspension) • Glass rod inspection • Well plate inspection system • Bio-sample thermal imaging • Wellplate imaging system • Crystal finder/classifier • Biaxial tissue tester • Two-photon microscopy Plate Inspection System Research

6. The Challenge Dinnerware Inspection • Many different dishes • 1 dish per second • Most difficult defect: • White bumps onwhite plates Defects

7. Can we image the defects? • Prototype with what you have (or loaners) • Area-scan camera (GigE) • Lighting • Directional : Desk lamp • Broad sources : Room lights, diffusers • NI Vision Development Module • Optimize lighting & camera placement • Tip : Replace camera with your eye

8. Okay, I see the defects, but can the computer? • Start with NI Vision Assistant • Fastest way to test processing functions • Estimate time using the “Performance Meter” • Quickly turn scripts into LabVIEW VIs

9. Okay, I see the defects, but can the computer? • Start with NI Vision Assistant • Fastest way to test processing functions • Estimate time using the “Performance Meter” • Quickly turn scripts into LabVIEW VIs

10. Proof of Principle • Are you confident in your plan yet? • If not, prototype in LabVIEW! • Combine acquisition and analysis • Tip : Use tester with fresh data or saved image sets • Practice good coding style • Prototypes Final version • Good code encourages trying new ideas • Documentation should be automatic

11. Going for it Ready to build your system? • Know your test set, criteria • Balance goals with sliding scales instead of all-or-nothing • Solve most pressing issues first • Example : Our 1st generation machine tested 1 plate type (their most popular) and only 4 defect types

12. Modular, Modular, Modular 1 2 3 Independent Stations • Bottom view • 3D imaging • Top view Lesson learned : • Needed to add baffles • Found interference between stations • Changed how plates cross gaps • Vibration issues PC NI PCIe-8235 4x GigE NI PCIe-1430 Dual CameraLink

13. Small defect imaging Glancing Angle • First version : • Next version: • Defects show up as dark spots: LED light Transmission Line scan Camera

14. Small Defects are Hard to Find! • Problems : • Defects are small, low contrast • Large gradients in image • Plate-to-plate variations • Image size (8MP!) • Must process in < 0.5 second • Solution: • A custom pixel-by-pixel threshold for each image. Defect!

15. Step 1 : Unwrap Image Problem : We just need rim pixels • Use image masks? • Longer process times • Still have large images Solution : IMAQ Unwrap • 8M pixel square -> 1.5M pixel strip • Aligns gradients, rim transitions in one direction

16. Step 2 : Create Custom Golden Master What should this image look like if it were perfect? • Remove defects using median smoothing • Tip : Use X Size >> Y Size to preserve gradients & edges • Performance Boost : Reduce image resolution , Smooth, then Resample back to original size. Median Smoothed “Golden Master” Unwrapped Original Defect Defect Removed!

17. Step 3 : Pixel-by-pixel Threshold Original Results “Golden Master” Threshold original image using IMAQ Compare Subtract a constant to set a “lower” threshold. Defect Found!

18. Benefits of Pixel-by-pixel Thresholds • Works with: • Gradients, edges, speckle, large dynamic contrasts • Every image checks against itself • Robust against image-image variations, changing lighting conditions • Fast (<100ms for 1.5MP) • Limited by smoothing performance

19. 3D Imaging • Simple inspection for geometric errors • Gouges, bulges, warp Warp examples

20. Laser Triangulation Laser Line Area Camera Original Threshold applied

21. Convert pixels to height Laser Line Area Camera Height = dy H WD q With a little more geometry, we can also correct for perspective :

22. 3D Laser Height Measurement • Each camera frame = 1 cross section (per laser line) • Tip : Add multiple laser lines for more cross sections • 250 um cross section resolution (100 FPS @ 1” per sec) • Tip : Reduce ROI for fastest frame rates • 100 um height resolution

23. Completed system • Fast development with NI tools: • Completed in < 3 months • Reliable • Inspected over 1 million dishes • Multiple follow-up systems

24. Conclusions • Invest in good prototyping practices • Prepare for unknown hurdles • Use modular, flexible architectures in hardware, layout, software • Defect finding algorithm • Pixel-by-pixel thresholds • Simple 3D laser scanner • Inexpensive, easy to setup

25. Questions?

26. NIWeek Vision SummitAugust 2–3, 2011 Austin, Texas