How do the ultrasonic and infrared sensors work?

Ultrasonic sensors — These sensors are used to detect an object or obstacle. These are based on sound waves. It means that the presence of an object is detected through transmission and reflection of sound waves. These sensors help robots to navigate from one location to another.

Infrared sensors — IR sensors use infrared rays that help in detecting the presence of an object. These sensors emit infrared light and observe its reflection to detect the obstacle or follow a particular path.