Here’s an easy-to-build robot base that combines a custom Arduino development board with inexpensive motors and tank-style tracks. It even comes with its own lithium polymer power pack and self-charging circuit, so you don’t need to add batteries.
To construct the DFRobotShop Rover you have to first assemble the twin motor gearbox and rubber treads -— both are pre-packaged products from Tamiya. Then it’s just a handful of screws and plastic rivets. Total build time is about an hour. Tip from me: use only your fingers when assembling the rubber treads; sharp tools can tear the rubber.
The Rover’s electronics are essentially an Arduino with a motor driver circuit. I recommend adding a bare-bones Arduino prototyping shield, and with some velcro tape, the shield will also work as a slip-proof shelf for the LiPoly battery.
To make the robot truly autonomous you’ll want to add sensors, like a Ping ultrasonic distance ranger. Pre-drilled holes at the front of the Rover accept Lynxmotion Servo Erector Set parts, and RobotShop promises that on the next version (available Fall 2011), they’ll add a prototyping area on the front end.
A final word of advice: consider swapping out the 3V motors included with the Tamiya gearbox kit for more efficient 6V versions (RobotShop #RB-Sbo-50); they’re under $2 each.