For more fun, if you have a second NXT brick, you can
make the Segway rider on this robot lean forwards and backwards via
Bluetooth remote control, which will cause the robot to start rolling
forward or backwards while staying balanced, just like a real Segway!
Many self-balancing robots (including the actual Segway
PT) use special gyroscopic or other sensors to detect the tilt angle
of the robot, but this robot uses only the NXT light sensor by aiming the sensor at the ground
and measuring reflected light, which will change slightly depending on
how close the sensor is to the ground.