Here’s a vid of a hamster, in a hamster ball, controlling a iRobot Create.

The hamster controls the robot by running in the ball in whatever direction he/she likes. The ball is supported on three rollers and an optical sensor measures which way and how fast the ball is spinning. Those values are fed into a microprocessor that controls the drive wheels to make the robot mimic the motion of the ball.

iRobot YouTube Channel