Selecting propellers for performance and noise shaping

• US 10,232,931 B2
• Filed: 12/18/2015
• Issued: 03/19/2019
• Est. Priority Date: 12/18/2015
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Huddleston, Jr., Howard Lee, Beckman, Brian C., Ko, Allan
• Primary Examiner(s): Kleinman, Lail A
• Application Number:
  US14/975,506
• Publication Number:
  US 20170174316A1
• Time in Patent Office: 1,187 Days
• Field of Search: None
• CPC Class Codes: B64C 11/00 Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
• CPC Class Codes: B64C 11/008 characterised by vibration absorbing or balancing means
• CPC Class Codes: B64C 27/32 Rotors
• CPC Class Codes: B64U 10/14 with four distinct rotor axes, e.g. quadcopters
• CPC Class Codes: B64U 2101/60 for transporting passengers; for transporting goods other than weapons
• CPC Class Codes: B64U 2201/10 autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS]
• CPC Class Codes: B64U 2201/20 Remote controls
• CPC Class Codes: G05D 1/101 specially adapted for aircraft
• CPC Class Codes: G05D 13/00 Control of linear speed; Control of angular speed; Control of acceleration or deceleration, e.g. of a prime mover

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.

Claims

1. An unmanned aerial vehicle comprising:

a frame;

a plurality of motors mounted to the frame, wherein the plurality of motors comprises a first set of motors and a second set of motors;

a first set of propellers, wherein each of the first set of propellers has a first critical speed, and wherein each of the first set of propellers is coupled to one of the first set of motors;

a second set of propellers, wherein each of the second set of propellers has a second critical speed, and wherein each of the second set of propellers is coupled to one of the second set of motors; 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 each of the first motors above the first critical speed at a first time; and

initiate a second operation of each of the second motors above the second critical speed at a second time,

wherein each of the first set of propellers is configured to emit a first sound at a first sound pressure level or a first frequency spectrum above the first critical speed,

wherein each of the second set of propellers is configured to emit a second sound at a second sound pressure level or a second frequency spectrum above the second critical speed,

wherein the second sound pressure level is different from the first sound pressure level, and

wherein the second frequency spectrum is different from the first frequency spectrum.

2. The unmanned aerial vehicle of claim 1,

wherein each of the first set of propellers has a first value of one of a radius, a mass, a number of blades, a thrust rating, a lift rating, a maneuverability rating or a speed rating, and

wherein each of the second set of propellers has a second value of the one of the radius, the mass, the number of blades, the thrust rating, the lift rating, the maneuverability rating or the speed rating.

3. The unmanned aerial vehicle of claim 1, further comprising a position sensor, and

wherein the computing device is further configured to at least:

determine a position of the aerial vehicle at a third time using the position sensor, wherein the third time follows the first time and precedes the second time;

determine that the position of the aerial vehicle at the third time corresponds to a noise limit; and

in response to determining that the position of the aerial vehicle at the third time corresponds to the noise limit,

initiate the second operation of each of the second motors above the second critical speed at the second time.

4. A method to operate an aerial vehicle having a first set of propellers and a second set of propellers, the method comprising:

initiating a first operation of each of a first set of motors at a first time, wherein each of the first set of motors is mounted to a frame of the aerial vehicle and coupled to one of the first set of propellers; and

initiating a second operation of each of a second set of motors at a second time, wherein each of the second set of motors is mounted to the frame of the aerial vehicle and coupled to one of the second set of propellers,

wherein each of the first set of propellers has a first sound rating,

wherein each of the second set of propellers has a second sound rating, and

wherein the first sound rating is different from the second sound rating.

5. The method of claim 4, further comprising:

stopping the first operation of each of the first set of motors at a third time,

wherein the third time is not prior to the second time.

6. The method of claim 4, wherein the first operation of each of the first set of motors at the first time is initiated at a first power level,

wherein the second operation of each of the second set of motors at the second time is initiated at a second power level, and

wherein the method further comprises:

initiating a third operation of each of the first set of motors at a third power level at the second time,

wherein the third power level is different from the first power level.

7. The method of claim 4, further comprising:

identifying a mission for the aerial vehicle;

determining a first attribute of the mission for the aerial vehicle;

selecting the first sound rating based at least in part on the first attribute of the mission for the aerial vehicle; and

coupling each of the first set of propellers having the first sound rating to one of the first set of motors prior to the first time.

8. The method of claim 7,

wherein the first attribute of the mission for the aerial vehicle comprises at least one of:

a location of an origin for the mission;

a location of a destination for the mission;

a dimension or a mass of a payload for the mission;

a course for the aerial vehicle during the mission;

a speed for the aerial vehicle during the mission;

an anticipated environmental condition to be encountered by the aerial vehicle during the mission;

an anticipated operational characteristic of the aerial vehicle during the mission;

or

an anticipated sound to be emitted by the aerial vehicle during the mission.

9. The method of claim 7, further comprising:

determining a second attribute of the mission for the aerial vehicle;

selecting the second sound rating based at least in part on the second attribute of the mission for the aerial vehicle; and

coupling each of the second set of propellers of the second sound rating to one of the second set of motors prior to the second time.

10. The method of claim 4, further comprising:

determining a position of the aerial vehicle at a third time using at least one sensor, wherein the third time is after the first time and prior to the second time; and

in response to determining the position of the aerial vehicle at the third time,

initiating the second operation of each of the second set of motors at the second time based at least in part on the position of the aerial vehicle at the third time.

11. The method of claim 4, further comprising:

determining an environmental condition in a vicinity of the aerial vehicle at a third time using at least one sensor, wherein the third time is after the first time and prior to the second time; and

in response to determining the environmental condition in the vicinity of the aerial vehicle at the third time,

initiating the second operation of each of the second set of motors at the second time based at least in part on the environmental condition in the vicinity of the aerial vehicle at the third time,

wherein the environmental condition in the vicinity of the aerial vehicle at the third time comprises at least one of;

a temperature;

a pressure;

a humidity;

a wind speed;

a wind direction;

a weather event;

a level of cloud coverage;

a level of sunshine;

or

a surface condition.

12. The method of claim 4, further comprising:

determining an operational characteristic of the aerial vehicle at a third time using at least one sensor, wherein the third time is after the first time and prior to the second time; and

in response to determining the operational characteristic of the aerial vehicle at the third time,

initiating the second operation of each of the second set of motors at the second time based at least in part on the operational characteristic of the aerial vehicle at the third time,

wherein the operational characteristic of the aerial vehicle at the third time comprises at least one of;

an altitude;

a course;

a speed;

a climb rate;

a descent rate;

a turn rate;

or

an acceleration.

13. The method of claim 4, further comprising:

determining information regarding at least one sound emitted by the aerial vehicle at a third time using at least one sensor, wherein the information regarding the at least one sound comprises at least one of a sound pressure level of the at least one sound or a frequency spectrum of the at least one sound; and

in response to determining information regarding the at least one sound emitted by the aerial vehicle at the third time,

initiating the second operation of each of the second set of motors at the second time.

14. The method of claim 4, wherein each of the first set of propellers has a first value of a parameter,

wherein each of the second set of propellers has a second value of the parameter, and

wherein the parameter comprises at least one of:

a diameter;

a mass;

a number of blades;

a critical speed;

a sound pressure level of a sound emitted at the critical speed;

a frequency spectrum of the sound emitted at the critical speed;

a rake angle;

a pitch angle;

a thrust rating;

a lift rating;

a speed rating;

or

a maneuverability rating.

15. The method of claim 4, further comprising:

identifying a transit plan for the aerial vehicle having at least one segment extending between an origin and at least one of a destination or at least one intervening waypoint;

selecting one of the first sound rating or the second sound rating based at least in part on the at least one segment;

coupling each of the first set of propellers of the first sound rating to one of the first set of motors prior to the first time; and

coupling each of the second set of propellers of the second sound rating to one of the second set of motors prior to the second time.

16. The method of claim 4, wherein the aerial vehicle is a quad-copter having two motors coupled to two propellers of the first sound rating and two motors coupled to two propellers of the second sound rating.

17. An unmanned aerial vehicle comprising:

a frame;

a first set of propellers, wherein each of the first set of propellers is of a first type, and wherein each of the first set of propellers is configured to emit a first sound at a first sound pressure level or a first frequency spectrum above a first critical speed;

a first set of motors, wherein each of the first set of motors is mounted to the frame and coupled to one of the first set of propellers;

a second set of propellers, wherein each of the second set of propellers is of a second type, and wherein each of the second set of propellers is configured to emit a second sound at a second sound pressure level or a second frequency spectrum above a second critical speed; and

a second set of motors, wherein each of the second set of motors is mounted to the frame and coupled to one of the second set of propellers,

wherein the first type is different from the second type,

wherein each of the first set of propellers is statically balanced and dynamically balanced, and

wherein at least one of the second set of propellers is at least one of statically imbalanced or dynamically imbalanced.

18. The unmanned aerial vehicle of claim 17, wherein each of the first set of propellers of the first type has a first value of a parameter,

wherein each of the second set of propellers of the second type has a second value of the parameter, and

wherein the parameter comprises at least one of:

a diameter;

a mass;

a number of blades;

a critical speed;

a sound pressure level of a sound emitted at the critical speed;

a frequency spectrum of the sound emitted at the critical speed;

a rake angle;

a pitch angle;

a thrust rating;

a lift rating;

a speed rating;

a maneuverability rating;

or

a sound rating.

19. The unmanned aerial vehicle of claim 17, wherein the first set of motors comprises a first motor and a second motor,

wherein the second set of motors comprises a third motor and a fourth motor,

wherein the first set of propellers comprises a first propeller coupled to the first motor and a second propeller coupled to the second motor, and

wherein the second set of propellers comprises a third propeller coupled to the third motor and a fourth propeller coupled to the fourth motor.

20. The unmanned aerial vehicle of claim 17, wherein the at least one of the second set of propellers comprises a first blade and a second blade, and

wherein at least one of a length, a width, a mass, a shape, a pitch angle, a blade angle, a rake angle or a material of the first blade is different from a corresponding one of a length, a width, a mass, a shape, a pitch angle, a blade angle, a rake angle or a material of the second blade.