What does it do?
This is REG•E and he is my first obstacle avoiding robot.
He works off two Lego motors powered by 4 AA batteries and for a brain he has an Arduino Duemilanove. He uses an ultrasonic range finder to 'see' what's in front of him. Motor control is thanks to the TIP120 transistor and this tutorial here: http://www.instructables.com/id/Use-Arduino-with-TIP120-transistor-to-control-moto/