I recently saw
a tutorial involving the cheap (~$20) digital calipers one can buy on one's shopping site of choice. While the calipers themselves have a few important limitations, the principle upon which they function is very interesting.
Essentially, they place a row of small, insulated pads on the main PCB next to a similar, but more widely-spaced, row on a PCB that's glued to the body of the calipers. As the two slide past each other, the capacitance of each pad on the first row changes in a predictable manner. A little math and you have a simple, precise linear encoder.
This got me thinking. PCBs are quite cheap, and these calipers can read down to ten microns (!) with a fairly simple setup. What if we used something like this the way some people here are using optical encoder strips? The optical strips are not easy to come by -- all of those I've seen have been salvaged from inkjet printers.
In addition, we could use this technique to create simple, precise rotary encoders. For example, the Mechaduino project has made amazing advances in low-price closed-loop stepper control, but they're still limited by the magnetic encoders they use. Replacing the encoder wheel with a PCB, and building the other half of the encoder into the Mechaduino PCB itself, could cut costs and increase accuracy.
Thoughts? Experiences?
Edited 1 time(s). Last edit at 06/16/2016 06:43PM by epicepee.
