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Originally Posted by Jeff Waegelin
How has your experience with the Banner sensors been? Do you have any advice on how to make them work most effectively? They seem like a pretty cheap and simple solution, especially considering the massive quantities we have from past kits. Given the cost differential compared to encoders (free, vs. $40-$50 apiece), would you recommend I try the Banner sensors for my summer project?
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The Banner sensors worked great, however there were some reasons we abandoned them. First, setting up an encoder based on Banner sensors takes up a lot of space (if you need to be able to measure direction as well as rotation, then you'll need 2 sensors per wheel). It's also important to note that different versions of the Banner sensors were included in the kit each year. There's 2 types: one that is designed for detecting retro-reflective tape, and the other which works for things like line following (looking at white tape, much closer to the sensor). To be honest though I don't think we had much trouble using either model with our wheel encoders. If you're using 2 sensors per wheel (to be able to determine direction), then you need to mount them carefully as the square waves generated by each encoder need to be 90 degrees out of phase. We used a pinwheel of alternating black and aluminum "pie slices" with the Banner sensor mounted about an inch away. Here's the best picture I could find that shows our Banner sensor wheel from 2003 and 2004:
