System and method for mitigating an effect of an excitation of a structural flexible mode of an aircraft

Patent metadata

Field	Value
Publication number	US-11845537-B2
Application number	US-202117540615-A
Country	US
Kind code	B2
Filing date	Dec 2, 2021
Priority date	Oct 25, 2018
Publication date	Dec 19, 2023
Grant date	Dec 19, 2023

Abstract

Systems and methods for controlling a fixed-wing aircraft during flight are disclosed. The aircraft comprises first and second flight control surfaces of different types. The method comprises determining that a pilot command of the first flight control surface will excite a structural flexible mode of the aircraft and then executing the pilot command of the first flight control surface in conjunction with a command of the second flight control surface to mitigate the effect of the excitation of the structural flexible mode of the aircraft.

First claim

What is claimed is:

1. A method for mitigating an effect of an excitation of a structural flexible mode of an aircraft during flight, the aircraft comprising ailerons for causing movement of the aircraft about a roll axis and a rudder for causing movement of the aircraft about a yaw axis, the method comprising:
receiving a pilot command of the ailerons, the pilot command of the ailerons having a characteristic that will cause the pilot command of the ailerons to excite the structural flexible mode of the aircraft; and then
executing the pilot command of the ailerons in conjunction with a mitigating command of the rudder configured to mitigate the effect of the excitation of the structural flexible mode of the aircraft:
wherein:
the mitigating command is of zero magnitude and duration when the pilot command is not susceptible to excite the structural flexible mode of the aircraft;
the mitigating command is generated through an application of transfer functions for applying a criterion, the criterion comprising a predetermined frequency susceptible of exciting the structural flexible mode of the aircraft; and
the pilot command of the ailerons is oscillatory and the characteristic includes the predetermined frequency of the criterion for the pilot command of the ailerons.

2. The method as defined in claim 1 , wherein the structural flexible mode includes bending of a vertical stabilizer of the aircraft.

3. The method as defined in claim 1 , wherein the pilot command of the ailerons is oscillatory and the characteristic is a predetermined frequency of concern for the pilot command of the ailerons.

4. The method as defined in claim 1 , wherein the characteristic includes a magnitude of the pilot command of the ailerons corresponding to a predetermined magnitude susceptible of exciting the structural flexible mode of the aircraft included in the criterion.

5. The method as defined in claim 1 , wherein the pilot command of the ailerons causes downward movement of a right wing of the aircraft and the mitigating command of the rudder causes a left deflection of the rudder.

6. The method as defined in claim 1 , wherein:
when high-lift flight control surfaces of the aircraft are in a retracted configuration, the mitigating command of the rudder has a first magnitude; and
when the high-lift flight control surfaces of the aircraft are in a deployed configuration, the mitigating command of the rudder has a second magnitude different from the first magnitude.

7. The method as defined in claim 1 , wherein a magnitude of the mitigating command of the rudder is dependent on a magnitude of the pilot command of the ailerons.

8. The method as defined in claim 1 , wherein the characteristic is dependent on an altitude of the aircraft.

9. The method as defined in claim 1 , wherein the characteristic is dependent on a speed of the aircraft.

10. The method as defined in claim 1 , wherein the characteristic is dependent on a weight of the aircraft.

11. The method as defined in claim 1 , wherein the characteristic is dependent on a fuel quantity in the aircraft.

12. The method as defined in claim 1 , wherein the pilot command of the ailerons and the mitigating command of the rudder are executed simultaneously.

13. A method for mitigating an effect of an excitation of a structural flexible mode of an aircraft during flight, the aircraft comprising first and second flight control surfaces of different types, the method comprising:
receiving a pilot command of one or more first flight control surfaces, the pilot command of the one or more first flight control surfaces having a characteristic that will cause the pilot command of the one or more first flight control surfaces to excite the structural flexible mode of the aircraft; and then
executing the pilot command of the one or more first flight control surfaces in conjunction with a mitigating command of one or more second flight control surfaces configured to mitigate the effect of the excitation of the structural flexible mode of the aircraft;
wherein:
the mitigating command is of zero magnitude and duration when the pilot command is not susceptible to excite the structural flexible mode of the aircraft;
the mitigating command is generated through an application of transfer functions for applying a criterion, the criterion comprising a predetermined frequency susceptible of exciting the structural flexible mode of the aircraft; and
the pilot command of the one or more first flight control surfaces is oscillatory and the characteristic includes the predetermined frequency of the criterion for the pilot command of the one or more first flight control surfaces.

14. The method as defined in claim 13 , wherein the one or more first flight control surfaces comprise an aileron and the one or more second flight control surfaces comprise a rudder.

15. The method as defined in claim 13 , wherein the characteristic includes a magnitude of the pilot command of the one or more first flight control surfaces corresponding to a predetermined magnitude susceptible of exciting the structural flexible mode of the aircraft included in the criterion.

16. The method as defined in claim 13 , wherein:
when high-lift flight control surfaces of the aircraft are in a retracted configuration, the mitigating command of the one or more second flight control surfaces has a first magnitude; and
when the high-lift flight control surfaces of the aircraft are in a deployed configuration, the mitigating command of the one or more second flight control surfaces has a second magnitude different from the first magnitude.

17. The method as defined in claim 13 , wherein a magnitude of the mitigating command of the one or more second flight control surfaces is dependent on an active high-lift configuration of the aircraft.

18. The method as defined in claim 13 , wherein a magnitude of the mitigating command of the one or more second flight control surfaces is dependent on a magnitude of the pilot command of the one or more first flight control surfaces.

19. The method as defined in claim 13 , wherein the characteristic is dependent on an altitude of the aircraft.

20. The method as defined in claim 13 , wherein the characteristic is dependent on a speed of the aircraft.

21. The method as defined in claim 13 , wherein the characteristic is dependent on a weight of the aircraft.

22. The method as defined in claim 13 , wherein the characteristic is dependent on a fuel quantity in the aircraft.

23. The method as defined in claim 13 , wherein the pilot command of the one or more first flight control surfaces and the mitigating command of the one or more second flight control surfaces are executed simultaneously.

24. The method as defined in claim 13 , wherein the first and second flight control surfaces are associated with different rotation axes of the aircraft.

25. The method as defined in claim 13 , wherein the one or more first flight control surfaces comprise a rudder and the one or more second flight control surfaces comprise an aileron.

26. The method as defined in claim 13 , wherein the one or more first flight control surfaces comprise an elevator and the one or more second flight control surfaces comprise an aileron.

Assignees

• Bombardier Inc

Inventors

• Therien Sylvain
• Reist David

Classifications

• B64C13/503 Primary

  Fly-by-Wire · CPC title

• B64C9/12

  surfaces of different type or function being simultaneously adjusted · CPC title

• B64C13/0421

  control sticks for primary flight controls · CPC title

• B64C19/02

  Conjoint controls · CPC title

• B64C9/00 Primary

  Adjustable control surfaces or members, e.g. rudders (trimming stabilising surfaces B64C5/10) · CPC title