The wheels are not syncro drive wheels, but more independent since each wheel has two RC-servos, one for direction and one to power to wheel. The robot has six RC-servos for three wheels. Its easy to add a nother wheel, or change the robots diameter 190 - 250 mm. I use litium hydride batteries, that last over 1,5 houres with 2 KG payload. To control it I use the PIC and the Transputer, the software I use is a cross C compiler for PC. Its open and expandable system that is hard to outgrow.
You can see it in action at http://www.ite.his.se/ite/~a94leesa
It was the book Minimalist mobile robotics that inspired its design. By Jonthan H.Connell, MIT Ph D Work, ISBN: 0-12-185230-X