This awesome robot can stay upright like a Segway, but without using any gyroscopes. The secret to this design is a light sensor on the front that faces the floor. The robot detects when its distance to the ground increases or decreases and the wheels rotate to get it back to the right height. This is happening constantly while the robot is running. If you start it balanced, it stays balanced. If you start it off leaning forward or backwards it will stay at that angle and end up rolling forward or backward, in a controlled fall. Pretty clever!
Originally posted on March 17, 2012.