https://phys.org/news/2018-07-drones-facial-gestures.html

"Most commercial drones today come with controllers which work really well, but sometimes you may find yourself in a situation where your hands are busy," notes computing science professor Richard Vaughan, who leads this research.

"Or maybe you weren't expecting to interact with a drone today so you don't have special equipment with you. We'd like to be able to command drones in these situations and make the interaction natural and intuitive."