Selecting propellers for performance and noise shaping

Patent metadata

Field	Value
Publication number	US-9745050-B2
Application number	US-201514975563-A
Country	US
Kind code	B2
Filing date	Dec 18, 2015
Priority date	Dec 18, 2015
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

Aerial vehicles may be operated with discrete sets of propellers, which may be selected for a specific purpose or on a specific basis. The discrete sets of propellers may be operated separately or in tandem with one another, and at varying power levels. For example, a set of propellers may be selected to optimize the thrust, lift, maneuverability or efficiency of an aerial vehicle based on a position or other operational characteristic of the aerial vehicle, or an environmental condition encountered by the aerial vehicle. At least one of the propellers may be statically or dynamically imbalanced, such that the propeller emits a predetermined sound during operation. A balanced propeller may be specifically modified to cause the aerial vehicle to emit the predetermined sound by changing one or more parameters of the balanced propeller and causing the balanced propeller to be statically or dynamically imbalanced.

First claim

What is claimed is:

1. An unmanned aerial vehicle comprising:
a frame;
a sound sensor;
a first motor mounted to the frame;
a second motor mounted to the frame;
a first propeller coupled to the first motor, wherein the first propeller is statically balanced and dynamically balanced;
a second propeller coupled to the second motor, wherein the second propeller is at least one of statically imbalanced or dynamically imbalanced, and wherein the second propeller is configured to emit a first sound having a first sound pressure level and within a first frequency spectrum when rotated at a critical speed; and
a computing device having a memory and one or more computer processors,
wherein the computing device is configured to at least:
initiate a first operation of the first motor at a first time;
determine information regarding at least a second sound emitted by the unmanned aerial vehicle at a second time using the at least one sound sensor, wherein the information regarding at least the second sound comprises at least a second sound pressure level and at least a second frequency spectrum, and wherein the second time follows the first time; and
initiate a second operation of the second motor at a third time based at least in part on the information regarding at least the second sound emitted by the unmanned aerial vehicle at the second time, wherein the third time follows the second time.

2. An unmanned aerial vehicle comprising:
a frame;
at least one position sensor;
a first motor mounted to the frame;
a second motor mounted to the frame;
a first propeller coupled to the first motor, wherein the first propeller is statically balanced and dynamically balanced;
a second propeller coupled to the second motor, wherein the second propeller is at least one of statically imbalanced or dynamically imbalanced, and wherein the second propeller is configured to emit a first sound having a first sound pressure level and within a first frequency spectrum when rotated at a critical speed; and
a computing device having a memory and one or more computer processors,
wherein the computing device is configured to at least:
initiate a first operation of the first motor at a first time;
determine a position of the aerial vehicle at a second time using the at least one position sensor, wherein the second time follows the first time;
initiate a second operation of the second motor at a third time based at least in part on the position of the aerial vehicle at the second time.

3. A method to operate an aerial vehicle having a first set of motors, a second set of motors, a first set of propellers and a second set of propellers, the method comprising:
identifying a preferred sound to be emitted by the aerial vehicle in flight;
determining at least one of a sound pressure level or a frequency spectrum of the preferred sound using at least one computer processor;
selecting a propeller based at least in part on the sound pressure level or the frequency spectrum of the preferred sound;
outfitting one of the first set of motors with the selected propeller prior to a first time, wherein the selected propeller is the at least one of the first set of propellers, and wherein the selected propeller is one of not statically balanced or not dynamically balanced;
initiating a first operation of each of the first set of motors at the first time, wherein each of the first set of motors is coupled to one of the first set of propellers; and
initiating a second operation of each of the second set of motors at a second time, wherein each of the second set of motors is coupled to one of the second set of propellers, and wherein the second time follows the first time.

4. The method of claim 3 , wherein the selected propeller comprises a first blade and a second blade, and
wherein a mass of the first blade is not equal to a mass of the second blade.

5. The method of claim 3 , wherein a center of mass of the selected propeller is not aligned with an axis of rotation of the selected propeller.

6. A method to operate an aerial vehicle having a first set of motors, a second set of motors, a first set of propellers and a second set of propellers, the method comprising:
initiating a first operation of each of the first set of motors at a first time, wherein each of the first set of motors is coupled to one of the first set of propellers;
identifying a sound emitted by a first propeller during the first operation using at least one computer processor, wherein the first propeller is one of the first set of propellers;
determining at least one of a sound pressure level or a frequency spectrum of the sound emitted by the first propeller during the first operation using the at least one computer processor;
determining at least one of a sound pressure level or a frequency spectrum of a preferred sound to be emitted by the first propeller in flight using the at least one computer processor;
identifying at least one of a first difference between the sound pressure level of the sound emitted by the first propeller during the first operation and the sound pressure level of the preferred sound to be emitted by the first propeller in flight or a second difference between the frequency spectrum of the sound emitted by the first propeller during the first operation and the frequency spectrum of the preferred sound to be emitted by the first propeller in flight using the at least one computer processor;
determining a modification to at least one parameter of the first propeller based at least in part on at least one of the first difference or the second difference using the at least one computer processor;
causing the modification to the at least one parameter of the first propeller prior to a second time, wherein the modification causes the first propeller to be at least one of not statically balanced or not dynamically balanced, and wherein the second time follows the first time;
initiating a second operation of each of the first set of motors at the second time; and
initiating a third operation of each of a second set of motors at a third time.

7. The method of claim 6 , wherein the at least one parameter of the first propeller is at least one of:
a mass of at least a first blade of the first propeller;
a shape of at least the first blade of the first propeller;
a lift profile of the first propeller; or
a drag profile of the first propeller.

8. The method of claim 7 , wherein causing the modification to the at least one parameter of the first propeller prior to the first time comprises at least one of:
forming a hole in the first blade;
reducing a width of the first blade;
reducing a length of the first blade;
removing a core from the first blade;
inserting a slug into the first blade;
exposing an opening in the first blade;
changing a blade angle of the first blade;
changing a rake angle of the first blade; or
changing a thickness of the first blade.

9. A method to operate an aerial vehicle having a first set of propellers and a second set of propellers, the method comprising:
determining a position of the aerial vehicle at a first time using at least one sensor; and
in response to determining the position of the aerial vehicle at the first time,
initiating a first operation of each of a first set of motors at a second time based at least in part on the position of the aerial vehicle at the first time, wherein the first time is not later than the second time, wherein each of the first set of motors is coupled to one of the first set of propellers, and wherein at least one of the first set of propellers is not statically balanced or is not dynamically balanced, and
initiating a second operation of each of a second set of motors a

Assignees

• Amazon Tech Inc

Inventors

• Beckman Brian C
• Ko Allan

Classifications

• B64U2201/10

  autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS] · CPC title

• G01C21/00

  Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 (measuring distance traversed on the ground by a vehicle G01C22/00; control of position, course, altitude or attitude of vehicles G05D1/00; traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968) · CPC title

• B64C11/00 Primary

  Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft · CPC title

• B64C2201/108

  Operations & Transport · mapped topic

• G05D1/101

  specially adapted for aircraft · CPC title