Obstacle sensor, based on TCRT5000, uses infrared diode and photo-receiver to detect obstacle in front of it - emitted light just reflects back to the sensor. Onboard, you'll find voltage comparator, ...

A DIY Robot comprised of two microcontrollers, namely the ESP32 and Arduino Nano; integrated with multiple sensors. An IR Sensor Array [TCRT5000] for Line Following, Ultrasonic Sensor for Obstacle ...