Amazon.com has been granted a new patent for a delivery drone that can respond to human gestures.

The concept is part of Amazon's goal to develop a fleet of unmanned aerial vehicles that can swiftly send packages to customers in 30 minutes or less. Issued earlier this week, the patent by the US Patent and Trademark Office may help Amazon grapple with how flying robots might interact with human bystanders and customers waiting on their doorsteps.

Depending on a person's gestures - a welcoming thumbs up, shouting or frantic arm waving - the drone can adjust its behaviour, according to the patent. The machine could release the package it's carrying, alter its flight path to avoid crashing, ask humans a question or abort the delivery, the patent said.

Among several illustrations in the design, a person is shown outside his home, flapping his arms in what Amazon describes as an "unwelcoming manner," to showcase an example of someone shooing away a drone flying overhead. A voice bubble comes out of the man's mouth, depicting possible voice commands to the incoming machine. (Amazon.com chief executive Jeff Bezos owns The Washington Post.)

"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.