https://www.cnbc.com/2018/03/22/amazons-has-an-idea-for-a-delivery-drone-that-understands-when-you-shout-at-it.html

Amazon has filed a patent for a delivery drone that responds when you call or wave at it. The patent was spotted by GeekWire and the concept drone is designed to recognize human gestures, and then respond accordingly. Gestures the drone would recognize include, for example, waving arms, pointing, the flashing of lights, and speech. (The illustration shows a man wildly waving his arms and with a speech bubble next to his mouth).

The patent was initially filed in July 2016 and published this week. "The human recipient and / or the other humans can communicate with the vehicle using human gestures to aid the vehicle along its path to the delivery location," the patent states. The patent gives an example of a "shooing" motion, which the drone would recognize and stop moving closer. The drone would also then adjust its speed and the direction it's moving in. If a person waves their arms in a welcoming manner, the drone can interpret the gesture as an instruction to deliver the package.