Sensor for Line Following Robots

One of the traditional ‘disciplines’ in which robots are supposed to compete is the Line Follower Competition. Robots go along a predrawn black line (usually duct tape) on a white-ish surface (usually paper, cardboard or plastic).

This discipline requires special sensors. Usually, these are made out of reflective optosensors (such as CNY70, LTH-209). This sensor contains a phototransistor and an infrared LED. These sensors are pointed at the surface on which the robot is supposed to show off its speed and agility. The LED emits infrared light on the surface and the phototransistor acts as a receiver. The black coloured line to follow reflects far less light than the white surface it is affixed on.