Amazon patents drone propellers that can say "watch out"

Spotted by The Register:

Amazon has filed a fascinating patent for automated aerial vehicle (AAV) technology.

The invention has two aspects, the first of which is the use of multiple propellors rotating in different directions to reduce noise. Amazon imagines one propellor rotating in one direction to provide lift. “While the second propeller may cause lift of the AAV,” the patent suggests, it “may also be operable to produce sound that cancels noise generated by the first propeller.”

“In some cases, an audio sensor (e.g., a microphone) located near the first propeller may detect the noise generated by the first propeller. A controller may be in direct or indirect communication with the audio sensor. The controller may be configured to receive a signal representing the noise detected by the audio sensor. The controller may also be in direct or indirect communication with the second propeller, and may cause the second propeller to produce anti-noise sound that cancels the noise generated by the first propeller.”

The second aspect of the patent suggests using propellors to communicate with people on the ground, in two ways.

The first is using propellors to make sound. Here's the explanation:

Suppose, for instance, that the AAV were delivering an inventory item to a location. Upon approaching the location, the AAV determines (e.g., based on a video signal fed as an input parameter to the controller via a camera) that a person is situated at or near an intended or a suitable landing area corresponding to the delivery location. Such an input parameter may satisfy a flight condition corresponding to an audible communication, such as a “Watch out!” warning message. Accordingly, the controller may determine and cause to implement modulations of the rotational speed of a propeller, thereby causing the propeller to produce a series of sounds that are audibly perceptible as “Watch out!”

A second method would see the drones figure out they need to alert humans to their presence. In such cases “light sources [e.g., light-emitting diodes (LEDs)] coupled to one or multiple propellers may be caused to intermittently emit light in a synchronized manner while the propellers are rotating to generate patterns that are visibly perceptible as 'HELLO'.”

Noise is major issue for the aviation industry: airport operators and aircraft manufacturers alike want planes to be as quiet as possible, so as not to get nearby residents grumpy. Amazon clearly gets this is researching ways to make its drones as quiet as can be.

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Comment by Rob_Lefebvre on March 31, 2016 at 3:44pm

What the hell?  The light thing has been done before!

Comment by Alpo Hassinen on March 31, 2016 at 9:49pm

Similar light system has been used in paramotors. At the end of this page there are some pictures: http://parinapojanjorinoita.blogspot.fi/2011_03_01_archive.html

Comment by Damian on April 1, 2016 at 4:24am

NASA is already working on noise reduction with multiple propellers - as part of their LEAPTech program. Instead of typical low frequency brum of piston engine it will sound like an UFO ... 

https://www.youtube.com/watch?v=RrRj04QFl8I

 

Comment by Damian on April 1, 2016 at 4:37am

Guy

I read in their PDF papers that they will be slightly reducing RPMs of individual propellers (what does not make any difference on the forward flight) to generate different harmonics for each propeller to reduce the total noise (superposition cancellation???) as much as feasible. Not sure if they have static or dynamic algorithm. Perhaps dynamic with external microphone would be more robust and generic ??

Comment by Damian on April 1, 2016 at 4:37am

As they have plenty of propellers they can really play with it ... 

Comment by Damian on April 1, 2016 at 4:40am

From the PDF: By instead having the same amount of power going through 12 propellers, each at slightly different rpm, it’s possible to dramatically decrease each blade passage harmonic (by a factor of 12) and shift the blade passage harmonic down into the broadband noise. This electric acoustic integration strategy has the potential to greatly reduce overall community noise, a detailed analysis effort is currently under way by Langley acousticians to quantify this benefit as well as develop auralizations of this considerably different noise signature due to its higher frequency content to insure human perception issues are captured comparative to a single propeller signature.

Comment by Kelly Schrock on April 1, 2016 at 12:51pm

Just to be clear: This isn't an April Fool's joke?

Comment by Kelly Schrock on April 1, 2016 at 8:12pm

Ironically, April 1 is the day people are apt to regard what they read on the internet with more than the normal amount of skepticism, including me. So I thought I would at least bring it up.

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