My client wanted a device that could inspect the interior of metal pipe sections and detect scratches, for quality assurance purposes. Endoscopic cameras are too expensive and so are industrial scanline cameras. So I looked into different methods of imaging the innards of a cylindrical bore.
A periscope works, and so does a dismantled webcam, but both suffer from a very limited field of view. I’d require to move the camera multiple times and stitch the images together, which would waste time. Finally, I came upon the idea of using a desktop scanner to make a scanline camera. A desktop scanner is essentially a camera with a very high resolution, more than what any off-the-shelf digital camera can offer. To take a picture of the insides of a pipe, we just have to insert it and rotate the pipe!
After hacking (and breaking) two scanners, I figured out how to convert a flatbed scanner into a scanline camera. Then I built the rest of the device – a control system, a graphical user interface (GUI) to the device and the automatic inspection software.
The operation of the device is simple, place the pipe section (job) to be inspected in the receptacle and click a button on the GUI, The control system (AVR micro-controller based) inserts the probe into the pipe, signals the PC (GNU/Linux based) to start scanning and rotates the job at the proper speed that provides a sharp image.
Image processing software takes over from this point on (I built this using a few OpenCV filters and an algorithm I made myself) and while the controller brings the probe back to `home position’, the result is displayed on the screen. Although it was first designed to detect linear scratches, I later incorporated most defects that go into making the job, like the tool mark shown in the picture.
Here is a video of the device at work.
I can build such customised inspection devices or simply the software, for different products (flat plates, solid parts, cylindrical parts) and a variety of manufacturing defects. Here is a product brief.
Next on the list, among other things, is an improved version of the defect detection and recognition software, with photo-metrography (measurement) capabilities.
I happen to be one of those lucky people whose business involves them doing what they find fun. It’s a lot of fun to build stuff.
Those who have experienced first hand, know the nice feeling that one gets when a project is done. You press a button, and the thing works!
And later when one reflects on the whole process of building it, one cannot help but notice how much more fun the process was.
There are so many problems that come up while going from thought to thing, and the flashes of insight that accompany their solutions.
It would be a shame if these experiences were not shared. As such I intend to share some of these experiences, here on this blog.
Watch this space. Here’s to starting a new journey!