Rotorcraft control mode transition smoothing

Patent metadata

Field	Value
Publication number	US-10691140-B2
Application number	US-201816108479-A
Country	US
Kind code	B2
Filing date	Aug 22, 2018
Priority date	Mar 1, 2017
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

In accordance with an embodiment, a method of operating a rotorcraft includes transitioning from a first mode to a second mode when a velocity of the rotorcraft exceeds a first velocity threshold. Transitioning between the first and second modes includes fading out a gain of a dynamic controller over a first period of time, and decreasing a value of an integrator of the dynamic controller over a second period of time.

First claim

What is claimed is:

1. A method of operating a rotorcraft, the method comprising:
operating the rotorcraft in a first mode comprising
determining an attitude based on a pilot stick signal generated by a pilot stick assembly,
determining an actuator command based on the determined attitude, determining the actuator command comprising using a first dynamic controller having an integrator, and
providing an output of the first dynamic controller to an actuator, wherein a translational speed or the attitude of the rotorcraft is proportional to an amplitude of the pilot stick signal in the first mode;

transitioning from the first mode to a second mode when a velocity of the rotorcraft exceeds a first velocity threshold, transitioning comprising
fading out a gain of the first dynamic controller over a first period of time, and
decreasing a value of the integrator over a second period of time; and

operating the rotorcraft in the second mode comprising providing an output of a rate controller to the actuator, wherein the output of the rate controller is proportional to the amplitude of the pilot stick signal.

2. The method of claim 1 , wherein determining the attitude based on the pilot stick signal comprises
determining the translational speed based on the pilot stick signal by determining a forward speed component based on a cyclic longitude stick control portion of the pilot stick signal and determining a lateral speed component based on a cyclic latitude stick control portion of the pilot stick signal; and
determining a pitch attitude based on the determined forward speed component and a roll attitude based on the determined lateral speed component.

3. The method of claim 1 , wherein determining the attitude based on the pilot stick signal comprises determining a pitch attitude based on a cyclic longitude stick control portion of the pilot stick signal and determining a roll attitude based on a cyclic latitude stick control portion of the pilot stick signal.

4. The method of claim 1 , further comprising transitioning from the second mode to the first mode when the velocity of the rotorcraft decreases below a second velocity threshold, transitioning from the second mode to the first mode comprising:
fading in the gain of the first dynamic controller over a third period of time, and
reactivating the integrator.

5. The method of claim 4 , further comprising:
fading in a gain of the pilot stick signal in the rate controller over a fourth period of time when a pilot stick of the pilot stick assembly is out of detent; and
fading out the gain of the pilot stick signal in the rate controller over a fifth period of time when the pilot stick of the pilot stick assembly is in detent.

6. The method of claim 4 , wherein the first velocity threshold is greater than the second velocity threshold.

7. The method of claim 1 , wherein decreasing the value of the integrator comprises coupling the output of the integrator to an input of the integrator via a first feedback path.

8. The method of claim 7 , wherein the first feedback path comprises a limiter.

9. The method of claim 1 , wherein the first mode comprises a translational rate command, wherein a speed of the rotorcraft is proportional to the pilot stick signal.

10. The method of claim 1 , wherein the first mode comprises an attitude command, wherein the attitude of the rotorcraft is proportional to the pilot stick signal.

11. The method of claim 1 , wherein:
the first mode comprises one of
a transitional rate command (TRC) mode,
an attitude command return to trim speed (ACRTT) mode,
an attitude command speed hold (ACSH) mode,
an attitude command attitude hold (ACAH) mode,
a rate command return to trim speed (RCRTT) mode, or
a rate command speed hold (RCSH) mode; and

the second mode comprises one of
the attitude command return to trim speed (ACRTT) mode,
the attitude command speed hold (ACSH) mode,
the rate command return to trim speed (RCRTT) mode,
a rate command speed hold (RCSH) mode, or
a rate command attitude hold (RCAH) mode.

12. A flight control system for a rotorcraft comprising:
a processor and a non-transitory computer readable storage medium with an executable program stored thereon, the executable program including instructions to:
receive a pilot control signal via a first interface of the processor;
in a first mode
determine an attitude based on the received pilot control signal,
determine an actuator command based on the determined attitude, determining the actuator command comprising executing a first dynamic controller that has an integrator, and
providing an output of the first dynamic controller to an actuator via a second interface of the processor, wherein a state of the rotorcraft corresponding to the attitude is configured to be proportional to the received pilot control signal; and

transitioning from the first mode to a second mode when a first condition of the rotorcraft crosses a first predetermined threshold, transitioning comprising
fading out a gain of the first dynamic controller over a first period of time, and
decreasing a value of the integrator over a second period of time; and

in the second mode, providing an output of a second dynamic controller to the actuator via the second interface of the processor, wherein the output of the second dynamic controller is proportional to the received pilot control signal.

13. The flight control system of claim 12 , wherein in the first mode, the received pilot control signal represents a translational speed command, the determined attitude is based on the translational speed command, and the first condition of the rotorcraft is a velocity of the rotorcraft.

14. The flight control system of claim 12 , wherein in the first mode, the received pilot control signal represents an attitude command, the determined attitude is based on the attitude command, and the first condition of the rotorcraft is a velocity of the rotorcraft.

15. The flight control system of claim 12 , wherein:
the determined attitude comprises a pitch attitude and a roll attitude;
executing the first dynamic controller comprises executing a first pitch dynamic controller having a pitch integrator and executing a first roll dynamic controller having a roll integrator; and
providing the output of the first dynamic controller to the actuator via the second interface of the processor comprises providing an output of the first pitch dynamic controller to a pitch actuator and providing an output of the first roll dynamic controller to a roll actuator.

16. The flight control system of claim 12 , wherein the executable program further includes instructions to
fade in a gain of the pilot control signal in the second dynamic controller when a pilot control stick is out of detent; and
fade out the gain of the pilot control signal in the second dynamic controller when the pilot control stick is in detent.

17. The flight control system of claim 12 , wherein the executable program further includes instructions to transition from the second mode to the first mode when the first condition of the rotorcraft decreases below a second predetermined threshold, wherein transitioning from the second mode to the first mode comprises:
fading in the gain of the first dynamic controller over a third period of time, and reactivating the integrator.

18. The flight control system of claim 17 , wherein the first predetermined threshold is greater than the second predetermined threshold.

19. The flight control system of claim 12 ,

Assignees

• Textron Innovations Inc

Inventors

• Kim Sung Kyun

Classifications

• G05D1/102

  specially adapted for vertical take-off of aircraft · CPC title

• G05D1/0858 Primary

  specially adapted for vertical take-off of aircraft · CPC title

• B64C13/507

  with artificial feel · CPC title

• B64C13/503

  Fly-by-Wire · CPC title

• B64C13/506

  overriding of personal controls; with automatic return to inoperative position · CPC title