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Photographer Chase Jarvis with a drone at Gas Works Park in Seattle.

What happens if a child or a dog wanders into range while a drone is dipping down to make a delivery? Amazon has an answer: a “virtual safety shroud” that the drone creates, potentially based on readings picked up by its propellers.

The detect-and-avoid system is described in a patent application published today. Among the inventors is Gur Kimchi, the vice president and co-founder of Amazon Prime Air’s drone delivery operation, so you know it’s serious.

Amazon traditionally doesn’t comment on its patent applications, but here’s how the safety shroud would work, based on the description in the application, which was filed in February:

“When an approaching object is detected by an object detection component, a safety profile may be executed to reduce or avoid any potential harm to the object and/or the aerial vehicle. For example, if the object is detected entering a safety perimeter of the aerial vehicle, the rotation of a propeller closest to the object may be stopped to avoid harming the object and rotations of remaining propellers may be modified to maintain control and flight of the aerial vehicle.”

One way to sense the object would be to mount a rangefinder on the drone, which would look out for objects entering a specified safety perimeter. The drone would be programmed either to stop its propellers, maneuver away from the object, or issue a warning signal.

Another technique would be to pick up readings from the propellers themselves. For example, if your dog sticks its nose into a drone’s business, the propeller could pick up on the intrusion by detecting a change in electrical current, a shift in vibrations or even a difference in the sound of the spinning blades.

If the propeller senses contact, or imminent contact, it would shut itself down.

Keeping the proper distance from children, dogs and even curious squirrels will be a big challenge when autonomous drones start making backyard deliveries. Seattle-based Amazon is already testing drone delivery services on a highly limited basis, and so are other companies such as Nevada-based Flirtey.

The Federal Aviation Administration is still considering regulations for situations where drones fly over people – and a sense-and-avoid system like the one proposed by Kimchi and his fellow Amazon inventors may well be one of the requirements.

Will the FAA’s requirements make the world safer for our furry friends as well as people? Let’s hope so. Backyard roadkill is probably the last thing you’d want to see when you go out to pick up a drone-delivered package.

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