Maintaining attitude control of unmanned aerial vehicles by varying centers of gravity

Patent metadata

Field	Value
Publication number	US-10745115-B2
Application number	US-201715435044-A
Country	US
Kind code	B2
Filing date	Feb 16, 2017
Priority date	Feb 16, 2017
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

Aerial vehicles may be configured to control their attitudes by changing one or more physical attributes. For example, an aerial vehicle may be outfitted with propulsion motors having repositionable mounts by which the motors may be rotated about one or more axes, in order to redirect forces generated by the motors during operation. An aerial vehicle may also be outfitted with one or more other movable objects such as landing gear, antenna and/or engaged payloads, and one or more of such objects may be translated in one or more directions in order to adjust a center of gravity of the aerial vehicle. By varying angles by which forces are supplied to the aerial vehicle, or locations of the center of gravity of the aerial vehicle, a desired attitude of the aerial vehicle may be maintained irrespective of velocity, altitude and/or forces of thrust, lift, weight or drag acting upon the aerial vehicle.

First claim

What is claimed is:

1. An unmanned aerial vehicle comprising:
an airframe;
a first propulsion motor mounted to the airframe;
a second propulsion motor mounted to the airframe;
a first landing skid rotatably mounted to the airframe, wherein the first landing skid is configured to rotate within a first range between a position corresponding to landing or takeoff operations and a position corresponding to forward flight operations;
a second landing skid rotatably mounted to the airframe, wherein the second landing skid is configured to rotate within a second range between a position corresponding to landing or takeoff operations and a position corresponding to forward flight operations; and
a control unit having at least one computer processor configured to at least:
determine a desired orientation of the aerial vehicle;
calculate a location of a center of gravity of the aerial vehicle corresponding to the desired orientation of the aerial vehicle;
cause the aerial vehicle to operate in flight with the first propulsion motor rotating at a first rotational speed and the second propulsion motor rotating at a second rotational speed prior to a first time;
determine that the first propulsion motor is not generating a desired level of force at the first time;
in response to determining that the first propulsion motor is not generating a desired level of force at the first time,
select a first position of the first landing skid and a second position of the second landing skid for causing the center of gravity of the aerial vehicle to be in the location corresponding to the desired orientation of the aerial vehicle based at least in part on the rotation of the second propulsion motor at the second rotational speed, wherein the first position is within the first range and the second position is within the second range;
cause the first landing skid to be rotated to the first position; and
cause the second landing skid to be rotated to the second position.

2. The unmanned aerial vehicle of claim 1 , further comprising an angle sensor, and
wherein the at least one computer processor is further configured to at least:
with the first landing skid in the first position and the second landing skid in the second position,
determine at least one of a first yaw angle, a first pitch angle or a first roll angle of the aerial vehicle by the angle sensor;
determine that the aerial vehicle is not in the desired orientation based at least in part on the at least one of the first yaw angle, the first pitch angle or the first roll angle;
select a third position of the first landing skid and a fourth position of the second landing skid based at least in part on the at least one of the first yaw angle, the first pitch angle or the first roll angle, wherein the third position is within the first range and the fourth position is within the second range;
cause the first landing skid to be rotated to the third position; and
cause the second landing skid to be rotated to the fourth position.

3. The unmanned aerial vehicle of claim 2 , wherein the at least one computer processor is further configured to at least:
with the first landing skid in the third position and the second landing skid in the fourth position,
determine at least one of a second yaw angle, a second pitch angle or a second roll angle of the aerial vehicle by the angle sensor;
determine that the aerial vehicle is in the desired orientation based at least in part on the at least one of the second yaw angle, the second pitch angle or the second roll angle; and
in response to determining that the aerial vehicle is in the desired orientation,
cause the first landing skid to be rotated to the first position; and
cause the second landing skid to be rotated to the second position.

4. The unmanned aerial vehicle of claim 1 , further comprising an engagement system having at least one payload engaged thereby,
wherein the engagement system is configured to translate the at least one payload in at least one direction,
wherein the location of the center of gravity is calculated based at least in part on a first position of the at least one payload, and
wherein the at least one computer processor is further configured to at least:
in response to determining that the first propulsion motor is not generating a desired level of force at the first time,
select a second position of the at least one payload corresponding to the location of the center of gravity based at least in part on the rotation of the first propulsion motor at the first rotational speed, the rotation of the second propulsion motor at the second rotational speed, the first position of the first landing skid and the second position of the second landing skid; and
cause the at least one payload to be translated from the first position of the at least one payload to the second position of the at least one payload.

5. A method for operating an aerial vehicle in flight, wherein the aerial vehicle comprises at least a first propulsion motor, a second propulsion motor and at least one movable object movably mounted thereto, and
wherein the method comprises:
identifying a first course, a first speed and a first orientation for the aerial vehicle;
selecting a first operating speed for the first propulsion motor based at least in part on the first course and the first speed;
selecting a second operating speed for the second propulsion motor based at least in part on the first course and the first speed;
determining a first location of a center of gravity of the aerial vehicle with the at least one movable object in the first position;
selecting a second location of the center of gravity of the aerial vehicle corresponding to the first orientation based at least in part on the first operating speed and the second operating speed;
determining a second position of the at least one movable object for causing the center of gravity of the aerial vehicle to be in the second location;
moving the at least one movable object from the first position to the second position; and
operating the first propulsion motor at the first operating speed;
operating the second propulsion motor at the second operating speed;
determining that the second propulsion motor is ineffective at a first time;
in response to determining that the second propulsion motor is ineffective at the first time,
selecting a third location of the center of gravity of the aerial vehicle based at least in part on the first orientation and ineffectiveness of the second propulsion motor;
determining a third position of the at least one movable object based at least in part on the third location of the center of gravity; and
moving the at least one movable object from the second position to the third position.

6. The method of claim 5 , wherein the at least one movable object comprises a first landing gear component rotatably joined to an airframe of the aerial vehicle by a first motorized hinge configured to pivot the first landing gear component about a first hinge axis, and
wherein the first position of the at least one movable object is associated with a first angular orientation of the first landing gear component about the first hinge axis,
wherein the second position of the at least one movable object is associated with a second angular orientation of the first gear component about the first hinge axis, and
wherein moving the at least one movable object from the first position to the second position comprises:
rotating the first landing gear component from the first angular orientation about the first hinge axis to the second angular orientation about the first hinge axis.

7. The method of claim 6 , wherein determining the second position of the at least one movable

Assignees

• Amazon Tech Inc

Inventors

• Kimchi Gur
• Shiosaki Dominic Timothy
• Welsh Ricky Dean

Classifications

• B64D31/06

  actuated automatically · CPC title

• B64U50/19

  using electrically powered motors · CPC title

• B64U50/30

  Supply or distribution of electrical power · CPC title

• B64U10/13

  Flying platforms · CPC title

• B64C25/10

  retractable, foldable, or the like · CPC title