The tracking sensor is actually an infrared sensor. Its working principle is to use the different reflectivity of infrared light to the color, then convert the strength of the reflected signal into a current signal. Welcome to the World of Sensors and Modules with Arduino! The Line Tracking Sensor Module gives our robotics projects the ability to track and follow lines or paths accurately. Built around the TCRT5000-style reflective pair (IR LED + phototransistor) and an LM393 comparator, it is commonly used in line-follower robots and. This tutorial is a comprehensive, practical guide to the TCRT5000 Infrared Line Tracking & Tracing Sensor Module (Leobot Product #251).