Program examples The robot drives untill it encounters an obstacle and makes a sound. The robot again drives untill it encounters an obstacle and then sounds an alarm. When it detects a substantial change in lightness of the ground, it makes a different sound and stops. Following a white line on dark ground - zigzag movements of robot to follow the edge of the white line. Following a line using a light-sensor that is attached to a constantly swaying arm, in order to avoid zigzag-movements while following the line.