TwoPotatoe is a customer-built balancing robot that in its latest form uses an Arduino Mega to receive commands from a custom-made controller via XBees and a Wixel to wirelessly send telemetry to a PC. The robot uses feedback from a MinIMU-9 v3 IMU module’s accelerometer and gyro to maintain its balance, and it uses the MinIMU’s compass to navigate. The drive system consists of two 37D mm metal gearmotors with encoders controlled by a VNH3SP30 motor driver carrier.
You can see videos and read more about how TwoPotatoe works in the how it works section of its site.
10 December 2014 update: The old video of Twopotatoe has been replaced with a newer one. TwoPotatoe has also undergone a few changes: Arduino Due instead of the Arduino Mega, new motor controllers, new personality, etc. For more information about the changes and to see some new pictures, check out TwoPotatoe’s website.