Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots. You can watch the clock in action in the video embedded below just under the ...

Given its significant loiter time, wide-range sensors ... for beyond line-of-sight operations. The Predator carries the Multi-Spectral Targeting System, which integrates an infrared sensor ...

(InfraRed remote control) A handheld, wireless device used to operate audio, video and other electronic equipment within a room using light signals in the infrared (IR) range. Infrared light ...