The Studica Robotics Cobra Line Follower Sensor consists of 4 IR LED/phototransistor pairs, making it a great detector for a line-following robot. The Line Sensor Board allows the robot to tell objects or surfaces apart based on how dark or light they are. It shines a beam of infrared light out onto the object, and measures how much light is reflected back.
Each sensor provides a separate analog voltage output. The sensor board is an infrared emitter/receiver that is able to differentiate between a dark surface (with low IR reflectivity – 3.3V to 5V) and a light surface (with high IR reflectivity – 0V to 0.5V). However, this range can vary depended on the installed height of the sensor board.
The optimum height distance is 3-5 mm; however, the reflectivity values will change depending on distance. A daylight filter is built into the sensor.