Spotlight on Vision
In my previous life I spent about 30-40% of my time doing vision applications. Most of the jobs I did involved using “smart cameras” which are self-contained vision systems where the frame grabber circuitry, image processing and I/O are built into the camera body. For a general description of vision systems check out the Primer… A great deal of our work in vision involved gauging and dimensioning, absence/presence of components, color verification and analysis. We did work in the automotive, pharmaceutical and medical device, metalforming and ceramic casting fields as well as quite a few injection molding inspections. We used primarily DVT cameras and systems before they were bought out by Cognex. We also did a few PPT, Avalon, Cognex and Keyence applications.
Despite the different methods of programming and systemizing the cameras and the varying sizes of objects to be inspected, the techniques used for most of the applications were similar. Translation tools were almost always used to locate the part, the resolution of the camera vs. the target was always at least 10x what would be required, and lighting was of paramount importance. It almost always took twice as long to debug the systems as the time we had allotted also. There was generally more support required after the installation too. This simply serves to emphasize the point I would like to make here: If your firm is planning to use an integrator to implement your vision application, ensure that they have many years of practical experience. Get references from customers they have installed multiple systems for and ask them about the applications that didn’t go so well also, and there will always be some of those.
The picture above illustrates one of several technigues that can be used that don’t involve the camera or the lighting, in this case the use of mirrors. This can multiply the camera angles though the image will generally be smaller, in addition parallax issues can make measurement difficult. A previous post described the use of ultraviolet ink in an application as well as proper use of napkins and happy hour.
Don’t be afraid to think outside the box!