This is LEX, my largest, fastest robot. He's got a base made out of Lexan, two 10" lawn-mower wheels, and geared motors with built-in encoder feedback. A third wheel, a caster, is mounted on the front. Near the back are two 12V gel-cell batteries, to supply 24 volts to the motors. One of the batteries will eventually provide the 12 volts needed for the video camera and wireless video transmitter unit. LEX is currently on hold, because he is in Deep Storage in the U.S. while I am in Italy.
Above is a picture of Lex's brain, which is a Microchip 16F877 microcontroller, coupled to two LM629 PID motor control chips, and two LMD-18200 H-Bridge motor driver chips. This was done on a PIC project board sold by Microchip, and was intended to be temporary. Before I had a chance to make a real PCB out of it, we moved to Italy.
Once we return to the U.S., my plan is to add several GP2D02 ranging sensors, a video camera and wireless transmitter.
Source Code: Sorry for those of you who have asked about source code for interfacing the LM629, but I left it in storage with all my other stuff in the U.S., so unfortunately I don't have the code here to post. If you are having trouble with the handshaking, etc, I will be glad to help you if I can. Just drop me a line.