This is as far as I've gotten on a resurrected VEX tank I made a few years ago. I'm trying to find what I did with the RC transmitter, as someone out on the net has found the pattern for the RC receiver, which should be easy enough to incorporate to the design.
In these photos, the AVR is a ATMEGA328, running just the positioning servo, and the stock VEX Ultrasonic range finder. (Yes, the PING))) example code will work with the VEX USRF.. Simply set one digital pin as the output (the USRF's Input) and one as Input (the USRF's output.), the code works the same. ;D )
I'm trying to also add a simple line-follower (the three sensors on the front) to follow the white line around a running track, but might have problems.. (the rest of the track is a brick red.) so this might be scrapped form the idea. Otherwise, yes, that is a 7805 voltage regulator being used to power the servo off the 9V.. Still looking at a 7.2V battery from the old project. (already made the adapter.) Simply plug into the Arduino, hit reset, and let it run!