We have used incremental in the past. We do have to zero them each time.
We use this one from USDigitial.
http://www.usdigital.com/products/en...tary/shaft/S4T
We mount them one stage up from our modules on a flexible shaft adapter. They are easy to change. We use to use 10 turn pots...that was a nightmare! They worked, but one short or loss of connection and they were toast.
I am very interested in the new embedded magnetic encoder in the vex planetary gearboxes. They have absolute, incremental, and index. That would be nice.