# US 11,111,009 B1 · Operating multirotor aircraft with enhanced yaw control

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- Number: US 11,111,009 B1
- Document ID: US11111009B1
- Status: Granted
- Kind: B1
- Application number: 15/592,866
- Filed: 2017-05-11
- Granted: 2021-09-07
- Earliest claimed: 2015-06-09
- Assignees: Amazon Technologies, Inc.
- Applicants: Amazon Technologies, Inc.
- Inventors: Brian C. Beckman; Michael John Elzinga; Scott Raymond Harris; Louis Leroi LeGrand, III; Frederik Schaffalitzky
- Web page: https://patentgrep.com/patent/US11111009B1

## CPC

- B64C 27/22: Compound rotorcraft, i.e. aircraft using in flight the features of both aeroplane and rotorcraft
- B64C 15/14: the jets being other than main propulsion jets (jet flaps B64C9/38)
- B64C 27/12: Rotor drives
- B64C 27/52: Tilting of rotor bodily relative to fuselage (of see-saw type construction B64C27/43)
- B64C 29/0033: {the propellers being tiltable relative to the fuselage}
- B64U 10/13: Flying platforms
- B64U 30/12: Variable or detachable wings, e.g. wings with adjustable sweep
- B64U 30/29: Constructional aspects of rotors or rotor supports; Arrangements thereof
- B64U 40/20: for in-flight adjustment of the base configuration
- B64U 50/13: using external fans or propellers
- B64U 50/19: using electrically powered motors
- B64U 50/30: Supply or distribution of electrical power
- B64U 20/60: UAVs characterised by the material
- B64U 2101/64: for parcel delivery or retrieval
- B64U 2201/10: autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS]
- B64C: AEROPLANES; HELICOPTERS
- B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR

## Abstract

This disclosure describes a configuration of a multirotor aircraft that will facilitate enhanced yaw control. The multirotor aircraft includes one or more adjustable members that will twist the frame of the multirotor aircraft, thereby adjusting the orientation of the motors and propellers and enhance the yaw control of the multirotor aircraft. In some implementations, the adjustable member(s) are passive and twist in response to differential thrusts generated by the propellers. In other implementations, the adjustable members are active and twist in response to a yaw command from the multirotor aircraft control system.

## Claims

### Claim 1

A method of operating a multirotor aircraft, comprising:
generating a first differential thrust between a first motor and a second motor, the first motor coupled to a first end of a first motor arm and the second motor coupled to a second end of the first motor arm, the first motor arm coupled to a front frame of the multirotor aircraft;
generating a second differential thrust between a third motor and a fourth motor, the third motor coupled to a first end of a second motor arm and the fourth motor coupled to a second end of the second motor arm, the second motor arm coupled to a rear frame of the multirotor aircraft, the front frame coupled to the rear frame via an adjustable member, and the front frame, the adjustable member, and the rear frame extending along an axis;
generating a first rotation of the front frame in a first direction about the axis in response to the first differential thrust; and
generating a second rotation of the rear frame in a second direction about the axis in response to the second differential thrust;
wherein the axis is transverse to axes of rotation of the first, second, third, and fourth motors.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
altering a first orientation of the first motor and a second orientation of the second motor due to the first rotation; and
altering a third orientation of the third motor and a fourth orientation of the fourth motor due to the second rotation.

### Claim 3 (depends on 1)

The method of claim 1, further comprising generating a yaw moment of the multirotor aircraft in response to the first rotation and the second rotation.

### Claim 4 (depends on 1)

The method of claim 1, wherein the adjustable member comprises at least one of a spring, a leadscrew, a gear, a bearing, a swivel, a joint, metal, fiberglass, carbon fiber, plastic, or an elastomeric material.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
twisting the adjustable member about the axis via a motor coupled to the adjustable member in response to a yaw command.

### Claim 6

A method of operating a multirotor aircraft, comprising:
generating a first differential thrust between a first motor and a second motor, the first motor coupled to a first portion of a frame of the multirotor aircraft, the frame extending along an axis and comprising the first portion and a second portion connected by an adjustable member; and
causing the multirotor aircraft to yaw by altering an orientation of the first portion of the frame with respect to the second portion of the frame about the axis via the adjustable member, the axis being transverse to axes of rotation of the first and second motors.

### Claim 7 (depends on 6)

The method of claim 6, wherein the first differential thrust is generated by rotating the first motor at a different speed than the second motor.

### Claim 8 (depends on 6)

The method of claim 6, wherein the orientation is altered in response to the first differential thrust generated between the first motor and the second motor of the first portion of the frame relative to a second differential thrust generated between a third motor and a fourth motor of the second portion of the frame.

### Claim 9 (depends on 8)

The method of claim 8, further comprising:
rotating the first motor and the third motor in a first direction; and
rotating the second motor and the fourth motor in a second direction.

### Claim 10 (depends on 8)

The method of claim 8, further comprising:
rotating each of the first motor, the second motor, the third motor, and the fourth motor in a first direction.

### Claim 11 (depends on 8)

The method of claim 8, wherein the orientation is altered by:
causing the first portion of the frame to rotate in a first direction about the axis; and
causing the second portion of the frame to rotate in a second direction about the axis.

### Claim 12 (depends on 6)

The method of claim 6, wherein the orientation of the first portion of the frame with respect to the second portion of the frame is altered via an actuator associated with the adjustable member.

### Claim 13 (depends on 12)

The method of claim 12, wherein the orientation is altered via the actuator in response to a yaw command.

### Claim 14 (depends on 6)

The method of claim 6, further comprising varying a stiffness of the adjustable member via a controller.

### Claim 15 (depends on 6)

The method of claim 6, wherein the orientation is altered by causing a wing of the multirotor aircraft to rotate with respect to the frame.

### Claim 16

A method of operating an aircraft, comprising:
generating a first differential thrust between a first motor and a second motor of the aircraft;
causing a first rotation of a first portion of a frame of the aircraft in a first direction about an axis via an adjustable member at least partially in response to the first differential thrust; and
causing a second rotation of a second portion of the frame of the aircraft in a second direction about the axis via the adjustable member;
wherein the first portion of the frame, the adjustable member, and the second portion of the frame extend along the axis;
wherein the first portion is coupled to the second portion via the adjustable member; and
wherein the axis is transverse to axes of rotation of the first and second motors.

### Claim 17 (depends on 16)

The method of claim 16, further comprising:
generating a second differential thrust between a third motor and a fourth motor of the aircraft;
wherein the second rotation is caused at least partially in response to the second differential thrust.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first motor and the second motor are coupled to opposing ends of a first motor arm coupled to the first portion of the frame; and
wherein the third motor and the fourth motor are coupled to opposing ends of a second motor arm coupled to the second portion of the frame.

### Claim 19 (depends on 16)

The method of claim 16, wherein the adjustable member comprises at least one of a spring, a leadscrew, a gear, a bearing, a swivel, a joint, metal, fiberglass, carbon fiber, plastic, an elastomeric material, or an actuator.

### Claim 20 (depends on 16)

The method of claim 16, further comprising:
twisting the adjustable member about the axis via an actuator coupled to the adjustable member in response to a yaw command.