TCRT5000 IR Infrared Line Follower Sensor Obstacle Avoidance Sensor is a carrier board for TCRT5000 reflective optical sensor. Although it is designed for use with line-following robots, it can be used in mini-sumo robots for line control. The board has a digital output. The concept of working of line follower sensor is related to light. We use here the behavior of light at the black and white surface. When light fall on a white surface it is almost fully reflected and in case of black surface light is completely absorbed. This behavior of light is used in building a line follower sensor.