Just thought I'd post this here since it uses an ArduIMU module as its brain.
This is just a standard balancing robot, using a kalman filter on the y axis to calculate absolute angle and then just a simple PID controller to send values to a Pololu Qik serial motor controller.
I am trying to make it more stable, etc. and am considering possible adding rotary encoders to the motor shafts for closed-loop control.
The main purpose of this project is to increase my knowledge of angle estimation and PID tuning so that I can implement auto-leveling on a quadrocopter. This balancing robot platform is much easier to test than a flying platform.
I have a better quality video that I will try to post soon. If anyone has any interest in better pictures or code, let me know.