Line / Wall Follower The line/wall follower IR/Ultrasonic sensor Robot is capable of following a black line on a white surface/wall autonomously and with no external control. The IR sensor is made up of an infrared LED and a phototransistor placed next to each other. The LED acts as a transmitter, and the phototransistor acts as a receiver. The Ultrasonic Sensor is a Transceiver Module (Transmitter + Receiver). It transmits High Frequency Ultrasonic Waves of frequency greater than 20 KHz. Intercepts the waves reflected by an obstacle. Electrical Signals ↔ Ultrasonic Signals ↔ Electrical Signals IR Sensor TCRT5000 Ultrasonic sensor HC-SR04 DC motor 9-12v motor driver l298n Microcontroller Arduino uno