Gear Tooth Sensors versus Encoders?

[Dave Flowerday]

Originally Posted by Danny Diaz

I completely understand why we're using gear tooth sensors, but have other teams experimented with other mechanisms for reliably measuring wheel rotation that doesn't break the bank?

Last year, we built our own encoders by using a pair of QRB1134 (http://www.fairchildsemi.com/pf/QR/QRB1134.html) sensors and a black/white disc attached to our wheel. We did it mainly because it's easier to mount for us than to try to attach an off-the-shelf encoder to our wheel module. The significant cost savings were a nice side benefit (the encoders we used to use were $50 a piece, the QRB1134s are $3/pair. You need to add a resistor or two to use the QRBs, but if you search for them on Google you'll find several websites of others who have used them in robotics applications (both for line following and making home-grown encoders).

It worked great and we're probably going to use those sensors again this year.