Aircraft autonomous pushback

Patent metadata

Field	Value
Publication number	US-9849972-B2
Application number	US-201414912692-A
Country	US
Kind code	B2
Filing date	Jul 21, 2014
Priority date	Aug 22, 2013
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

The invention provides methods and systems for controlling speed of an aircraft during an autonomous pushback maneuver, i.e. under the aircraft's own power without a pushback tractor. The method includes applying a torque to at least one landing gear wheel of the aircraft, the torque being in a direction opposite to the backwards rolling direction of rotation of the landing gear wheel. The torque applied does not exceed a limit for ensuring aircraft longitudinal stability. For longitudinal stability the torque applied should not cause the aircraft to risk a tip-over event.

First claim

The invention claimed is:

1. A method of controlling speed of an aircraft during backwards motion of the aircraft when in contact with the ground, the method comprising:
applying a torque to at least one landing gear wheel of the aircraft, the torque is in a direction opposite to the backwards rolling direction of rotation of the landing gear wheel,
wherein the torque applied does not exceed a limit for ensuring aircraft longitudinal stability,
wherein the torque applied does not exceed a limit at which aircraft longitudinal stability is ensured such that the aircraft cannot tip back onto the aircraft tail,
wherein the torque applied does not exceed a limit at which aircraft longitudinal stability is ensured such that a nose landing gear of the aircraft does not part contact with the ground, and
wherein the torque applied does not exceed a limit at which aircraft longitudinal stability is ensured such that a substantially vertical load through a nose landing gear wheel does not fall below a threshold at which a steering centring device maintains the wheel of the nose landing gear straight.

2. The method according to claim 1 , wherein the torque limit is based upon one or more of the following instantaneous aircraft parameters when the torque is applied: a slope angle of the ground over which the aircraft is moving; the centre of gravity of the aircraft; the mass of the aircraft; an aircraft inertia moment around the aircraft lateral (y) axis; the backwards speed of the aircraft.

3. The method according to claim 1 , wherein the backwards motion of the aircraft is effected by a wheel actuator carried by the aircraft for driving one or more of the aircraft's landing gear wheels in rotation.

4. The method according to claim 1 , wherein the backwards motion of the aircraft is effected autonomously in the absence of an external tractor unit.

5. The method according to claim 1 , wherein the backwards motion of the aircraft is effected by gravity due to a slope angle of the ground over which the aircraft is moving.

6. The method according to claim 1 , wherein the step of applying torque to the landing gear wheel comprises applying a braking torque to the wheel using a friction brake assembly.

7. The method according to claim 6 wherein the aircraft speed is measured and if this speed exceeds a predetermined limit at which the aircraft longitudinal stability cannot be ensured then an indication is displayed in the aircraft cockpit.

8. The method according to claim 6 , wherein the braking torque is initiated by a pilot input.

9. The method according to claim 6 , where the braking torque is effected by a braking control system.

10. The method according to claim 6 , wherein the braking torque is effected by a park brake system.

11. The method according to claim 9 , wherein the aircraft has N braking wheels and the braking control system sends a braking command to a number n of the braking wheels where n<N.

12. The method according to claim 9 , wherein the braking control system limits the maximum braking clamping pressure applicable to the friction brake assemblies to no more than a limit at which the aircraft longitudinal stability is ensured.

13. The method according to claim 12 , wherein the maximum braking clamping pressure is variable depending on the mass and longitudinal centre of gravity position of the aircraft.

14. The method according to claim 9 , wherein the braking control system implements a braking law that commands initially a low brake pressure which rises with increasing time.

15. The method according to claim 3 , wherein the braking torque is applied whilst the wheel actuator is driving the aircraft backwards.

16. The method according to claim 15 , wherein the wheel actuator torque and the braking torque are controlled by a common controller.

17. The method according to claim 16 , wherein the controller receives input of the aircraft speed and controls the wheel actuator torque and the braking torque towards a target speed.

18. The method according to claim 1 , wherein the step of applying torque to the landing gear wheel comprises applying a braking torque to the wheel using a generator.

19. The method according to claim 18 , wherein the generator is coupled either to an electrical network of the aircraft or to a resistor for dissipating the electrical energy generated by the generator.

20. The method according to claim 18 , wherein the generator is a motor/generator used to drive one or more of the aircraft's landing gear wheels in rotation to effect the backwards motion of the aircraft.

21. The method according to claim 20 , wherein the motor/generator is selectively coupled to the landing gear wheel(s) by a drive path.

22. The method according to claim 21 , wherein the drive path includes a gear mounted to the wheel rim and a pinion, wherein the pinion is moveable between an engaged position in which the pinion is in driving engagement with the wheel gear and a disengaged position in which the pinion is physically separated from the wheel gear.

23. An autonomous pushback braking system for an aircraft having a wheel drive system for driving one or more of the aircraft's landing gear wheels in rotation, wherein the wheel drive system is operable to drive the wheel in rotation to effect backwards motion of the aircraft when in contact with the ground, and a means for applying a torque to at least one landing gear wheel of the aircraft, the torque is in a direction opposite to the backwards rolling direction of rotation of the landing gear wheel, wherein the torque applied does not exceed a limit for ensuring aircraft longitudinal stability,
wherein the torque applied does not exceed a limit at which aircraft longitudinal stability is ensured such that the aircraft cannot tip back onto the aircraft tail,
wherein the torque applied does not exceed a limit at which aircraft longitudinal stability is ensured such that a nose landing gear of the aircraft does not part contact with the ground, and
wherein the torque applied does not exceed a limit at which aircraft longitudinal stability is ensured such that a substantially vertical load through a nose landing gear wheel does not fall below a threshold at which a steering centring device maintains the wheel of the nose landing gear straight.

24. The system according to claim 23 , further comprising a friction brake assembly for applying a braking torque to the wheel.

25. The system according to claim 23 , further comprising a sensor for determining the aircraft speed relative to the ground.

26. The system according to claim 25 , further comprising a cockpit indicator for indicating to a pilot when the aircraft speed exceeds a predetermined limit at which the aircraft longitudinal stability cannot be ensured.

27. The system according to claim 24 , further comprising a braking control system for sending a braking command to the friction brake assembly.

28. The system according to claim 27 , wherein the braking control system is adapted to receive a pilot braking input.

29. The system according to claim 24 , further comprising a park brake system for sending a braking command to the friction brake assembly.

30. The system according to claim 27 , wherein the aircraft has N braking wheels and the braking control system is adapted to send a braking command to a number n of

Assignees

• Airbus Operations Ltd

Inventors

• Morris James
• Colosimo Antonio

Classifications

• B64C25/405 Primary

  Powered wheels, e.g. for taxing · CPC title

• B60T8/00 Primary

  Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force (by changing number of effective brake cylinders in power brake systems B60T17/10) · CPC title

• B60T8/1703

  for aircrafts · CPC title

• B64C25/34

  wheeled type, e.g. multi-wheeled bogies · CPC title

• B60T8/32

  responsive to a speed condition, e.g. acceleration or deceleration ({using electrical circuitry or regulation means B60T8/17} ; B60T8/28 takes precedence; electric devices on electrically propelled vehicles indicating the wheel slip B60L3/10; measuring linear or angular speed per se G01P3/00) · CPC title