System and method for gimbal lock avoidance in an aircraft

Patent metadata

Field	Value
Publication number	US-11536565-B2
Application number	US-201916448772-A
Country	US
Kind code	B2
Filing date	Jun 21, 2019
Priority date	Jun 21, 2019
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

A rotorcraft is described and includes an inertial measurement unit (“IMU”) sensor mounted to the rotorcraft, the IMU sensor oriented relative to the rotorcraft such that a roll attitude of the rotorcraft occurs about a Z-axis and has a range of ±90 degrees, a pitch attitude of the rotorcraft occurs about an X-axis and has a range of ±180 degrees, and a yaw attitude of the rotorcraft occurs about a Y-axis and has a range of ±180 degrees.

First claim

What is claimed is:

1. A rotorcraft comprising:
an integrated fuselage and wing comprising first and second ends;
propulsion assemblies connected proximate the first and second wing ends; and
an inertial measurement unit (“IMU”) sensor mounted to the integrated wing and fuselage and defining a roll attitude, a pitch attitude, and a yaw attitude of the rotorcraft, the IMU sensor oriented relative to the rotorcraft such that a roll attitude of the rotorcraft is defined by the IMU sensor to occur about a Z-axis of the rotorcraft and has a range of ±90 degrees, a pitch attitude of the rotorcraft is defined by the IMU sensor to occur about an X-axis of the rotorcraft and has a range of ±180 degrees thereby to prevent a gimbal lock situation that occurs when the pitch attitude of the rotorcraft is outside a range of approximately ±90 degrees, and a yaw attitude of the rotorcraft is defined by the IMU sensor to occur about a Y-axis of the rotorcraft and has a range of ±180 degrees;
wherein the Z-axis of the rotorcraft extends normal to the integrated fuselage and wing, the X-axis of the rotorcraft extends parallel to a longitudinal axis of the integrated fuselage and wing, and the Y-axis of the rotorcraft extends perpendicular to the X-axis of the rotorcraft and the Z-axis of the rotorcraft.

2. The rotorcraft of claim 1 , wherein the IMU is mounted to a side of the integrated fuselage and wing.

3. The rotorcraft of claim 1 , wherein each of the propulsion assemblies comprises a pylon having a rotor system disposed at a first end thereof and a tail boom disposed at a second end thereof.

4. The rotorcraft of claim 1 comprising a tail sitter aircraft.

5. A method comprising:
mounting an inertial measurement unit (“IMU”) sensor to an aircraft; and
updating the IMU sensor by:
setting an updated pitch attitude of the IMU sensor to a previous positive roll attitude of the IMU sensor;
setting an updated roll attitude of the IMU sensor to a previous negative pitch attitude of the IMU sensor; and
setting an updated yaw attitude of the IMU sensor to a previous positive yaw attitude of the IMU sensor minus 90 degrees;

such that the updated roll attitude of the rotorcraft is defined by the IMU sensor to occur about a Z-axis of the rotorcraft and has a range of ±90 degrees, the updated pitch attitude of the rotorcraft is defined by the IMU sensor to occur about an X-axis of the rotorcraft and has a range of ±180 degrees thereby to prevent a gimbal lock situation that occurs when an actual pitch attitude of the rotorcraft is outside a range of approximately ±90 degrees, and the updated yaw attitude of the rotorcraft is defined by the IMU sensor to occur about a Y-axis of the rotorcraft and has a range of ±180 degrees.

6. The method of claim 5 , wherein the updating further comprises:
updating the IMU sensor by:
setting an updated pitch rate of the IMU sensor to a previous positive roll rate of the IMU sensor;
setting an updated roll rate of the IMU sensor to a previous negative pitch rate of the IMU sensor; and
setting an updated yaw rate of the IMU sensor to a positive yaw rate of the IMU sensor.

7. The method of claim 5 , wherein the aircraft comprises a tail sitter aircraft.

8. The method of claim 5 , wherein the mounting comprises mounting the IMU sensor to a fuselage of the aircraft.

9. The method of claim 5 , wherein the mounting comprises mounting the IMU sensor to a wing of the aircraft.

10. The method of claim 5 , wherein the updating further comprises:
updating the IMU sensor by:
setting an updated pitch attitude of the IMU sensor to a previous negative roll attitude of the IMU sensor;
setting an updated roll attitude of the IMU sensor to a previous positive pitch attitude of the IMU sensor; and
setting an updated yaw attitude of the IMU sensor to a previous positive yaw attitude of the IMU sensor plus 90 degrees.

Assignees

• Bell Textron Inc
• Textron Innovations Inc

Inventors

• Kim Sung Kyun

Classifications

• G01C21/18 Primary

  Stabilised platforms, e.g. by gyroscope · CPC title

• B64U2201/104

  using satellite radio beacon positioning systems, e.g. GPS · CPC title

• B64C13/16

  actuated automatically, e.g. responsive to gust detectors · CPC title

• B64C29/02

  having its flight directional axis vertical when grounded · CPC title

• G01C9/005 Primary

  specially adapted for use in aircraft · CPC title