This robot is still undergoing construction.
Challenger is a tracked sumo bot, it will (when finished) use 38Khz opponent detectors (IR). The tracks were bought from Solarbotics and are made to pair with their GM motor range.
They are easy to put together and should be great. The only issue with the tracks is that they are molded plastic and as such have no grip. To solve this problem I have glued rubber from an old bike
innertube onto each tread.
Parts and resources list for Challenger: