I recently had to build an infrared close proximity sensor that could tell if something was dropped in a parcel delivery drop box. After some searching, I ended up using a microcontroller ... Here is ...

The robot uses a whopping 32 IR sensors to follow a black line across a concrete workshop floor, adjusting its path using a steering motor salvaged from a power wheelchair. An Arduino Mega Pro ...

In the real world, missile systems use advanced radars, infrared sensors ... targeting data for the launcher, an Arduino Uno uses an ultrasonic sensor pair mounted atop a servo.