COMBINED PITCH AND FORWARD THRUST CONTROL FOR UNMANNED AIRCRAFT SYSTEMS

• US 20170300067A1
• Filed: 04/18/2016
• Published: 10/19/2017
• Est. Priority Date: 04/18/2016
• Status: Active Grant

• Current Assignee: L3 Technologies, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Latitude Engineering LLC (L3Harris Technologies, Inc.)
• Inventors: Douglas, Jason Michael K., Armer, Justin, Murphy, Carlos
• Granted Patent: US 10,162,367 B2
• Time in Patent Office: Days
• CPC Class Codes: B64C 29/0025 the propellers being fixed relative to the fuselage
• CPC Class Codes: B64U 10/13 Flying platforms
• CPC Class Codes: B64U 10/20 Vertical take-off and landing [VTOL] aircraft flying platforms B64U10/13; helicopters B64U10/17
• CPC Class Codes: B64U 2201/00 UAVs characterised by their flight controls
• CPC Class Codes: B64U 2201/20 Remote controls
• CPC Class Codes: B64U 30/10 Wings
• CPC Class Codes: B64U 30/20 Rotors; Rotor supports
• CPC Class Codes: B64U 30/29 Constructional aspects of rotors or rotor supports; Arrangements thereof
• CPC Class Codes: B64U 50/11 using internal combustion piston engines
• CPC Class Codes: B64U 50/18 Thrust vectoring
• CPC Class Codes: B64U 70/80 Vertical take-off or landing, e.g. using rockets rotorcrafts B64U10/10; VTOL aircraft B64U10/20
• CPC Class Codes: G05D 1/0011 associated with a remote control arrangement
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

An unmanned aircraft includes a forward propulsion system comprising one or more forward thrust engines and one or more corresponding rotors coupled to the forward thrust engines; a vertical propulsion system comprising one or more vertical thrust engines and one or more corresponding rotors coupled to the vertical thrust engines; and a pitch angle and throttle control system, comprising a processor configured to receive a first pitch angle command; and generate a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the aircraft.

Claims

1. An unmanned aircraft, comprising:

a forward propulsion system comprising a forward thrust engine and a first rotor coupled to the forward thrust engine;

a vertical propulsion system comprising a vertical thrust engine and a second rotor coupled to the vertical thrust engine;

a pitch angle and throttle control system, comprising;

a controller comprising an input coupled to receive a velocity signal indicating a determined amount of forward velocity and being configured to generate a pitch angle command associated with the determined amount of forward velocity;

a splitting block comprising an input to receive the pitch angle command and being configured to generate a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the aircraft;

an output coupled to provide the second pitch angle command to the vertical propulsion system and the forward thrust engine throttle command to the forward propulsion system.

2. The unmanned aircraft of claim 1, wherein the splitting block comprises a processor configured to perform the operations comprising:

comparing a determined bounded pitch angle for the aircraft to the pitch angle corresponding to the pitch angle command;

generating a reduced pitch angle command so the resultant aircraft pitch angle does not exceed the bounded pitch angle; and

generating the forward thrust engine throttle command based on the reduced pitch angle command.

3. The unmanned aircraft of claim 1, wherein generating the forward thrust engine throttle command based on the reduced pitch angle command comprises:

determining a forward velocity generated by the limited pitch angle command;

determining a difference in forward velocity between forward velocity generated by the limited pitch angle and the determined amount of forward velocity;

generating a residual pitch angle command based on the determined difference in forward velocity; and

converting the residual pitch angle command to the forward thrust engine throttle command.

4. The unmanned aircraft of claim 3, wherein the residual pitch angle command is of a magnitude estimated to provide sufficient forward thrust to account for the determined difference in forward velocity.

5. The unmanned aircraft of claim 1, wherein the determined amount of forward velocity comprises a velocity error between a desired aircraft velocity and an actual aircraft velocity.

6. The unmanned aircraft of claim 1, wherein the velocity signal comprises a velocity error signal.

7. The unmanned aircraft of claim 1, wherein forward thrust engine comprises an internal combustion engine or a motor.

8. The unmanned aircraft of claim 1, wherein the controller comprises proportional-integral-derivative (PID) controller to provide the forward thrust pseudo-control in the time domain.

9. The unmanned aircraft of claim 8, wherein the forward thrust pitch angle command is given by:

10. The unmanned aircraft of claim 1, wherein providing the second pitch angle command to the vertical propulsion system comprises converting the second pitch angle command to a VTOL rotor command and providing the VTOL rotor command to the vertical propulsion system.

11. The unmanned aircraft of claim 1, wherein the unmanned aircraft is a multirotor aircraft and the vertical propulsion system comprises a plurality of vertical thrust engines and corresponding rotors.

12. The unmanned aircraft of claim 1, wherein the unmanned aircraft is a hybrid multirotor aircraft.

13. The unmanned aircraft of claim 1, wherein the bounded pitch angle comprises a maximum pitch angle.

14. The unmanned aircraft of claim 1, wherein the bounded pitch angle comprises a range of pitch angles between a minimum pitch angle and a maximum pitch angle.

15. An unmanned aircraft system, comprising:

an unmanned aircraft, comprising;

a forward propulsion system comprising a forward thrust engine and a first rotor coupled to the forward thrust engine;

a vertical propulsion system comprising a vertical thrust engine and a second rotor coupled to the vertical thrust engine;

an onboard aircraft controller comprising a first output coupled to the forward propulsion system and a second output coupled to the vertical propulsion system; and

a first communication transceiver coupled to the aircraft controller configured to communicate with a remote control system;

the remote control system, comprising;

a second communication transceiver configured to communicate with the unmanned aircraft; and

an aircraft control system communicatively coupled to the second communication transceiver; and

a pitch angle and throttle control system, comprising a processor configured to;

receive a velocity signal indicating a determined amount of forward velocity and being configured to generate a pitch angle command associated with the determined amount of forward velocity;

receive the pitch angle command and being configured to generate a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the aircraft;

provide the second pitch angle command to the vertical propulsion system and the forward thrust engine throttle command to the forward propulsion system.

16. The unmanned aircraft system of claim 15, wherein the pitch angle and throttle control system is part of the onboard aircraft controller.

17. The unmanned aircraft system of claim 15, wherein the pitch angle and throttle control system is part of the aircraft control system of the remote control system.

18. The unmanned aircraft system of claim 17, wherein the second pitch angle command and the forward thrust engine throttle command are sent to the vertical propulsion system and the forward propulsion system, respectively, via the first and second communication transceivers.

19. The unmanned aircraft system of claim 15, wherein the pitch angle and throttle control system is part of both the onboard aircraft controller the aircraft control system of the remote control system.

20. The unmanned aircraft system of claim 15, wherein the unmanned aircraft is a multirotor aircraft and the vertical propulsion system comprises a plurality of vertical thrust engines and corresponding rotors.

21. The unmanned aircraft system of claim 15, wherein the unmanned aircraft is a hybrid multirotor aircraft.

22. The unmanned aircraft system of claim 15, wherein the bounded pitch angle comprises a maximum pitch angle.

23. The unmanned aircraft system of claim 15, wherein the bounded pitch angle comprises a range of pitch angles between a minimum pitch angle and a maximum pitch angle.

24. An unmanned aircraft, comprising:

a forward propulsion system comprising a forward thrust engine and a first rotor coupled to the forward thrust engine;

a vertical propulsion system comprising a vertical thrust engine and a second rotor coupled to the vertical thrust engine; and

a pitch angle and throttle control system, comprising a processor configured to receive a first pitch angle command; and

generate a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the aircraft.

25. The unmanned aircraft of claim 24, wherein the processor further performs the operations comprising:

comparing a determined bounded pitch angle for the aircraft to the pitch angle corresponding to the first pitch angle command;

generating a reduced pitch angle command so the resultant aircraft pitch angle does not exceed the bounded pitch angle; and

generating the forward thrust engine throttle command based on the reduced pitch angle command.

26. The unmanned aircraft of claim 25, wherein generating the forward thrust engine throttle command based on the reduced pitch angle command comprises determining a residual amount of forward thrust needed to compensate for the reduced pitch angle command and generating the forward thrust engine throttle command to at least partially provide the residual amount of forward thrust needed.

27. The unmanned aircraft of claim 25, wherein generating the forward thrust engine throttle command based on the reduced pitch angle command comprises:

determining a forward velocity generated by the limited pitch angle command;

determining a difference in forward velocity between forward velocity generated by the limited pitch angle and the determined amount of forward velocity;

generating a residual pitch angle command based on the determined difference in forward velocity; and

converting the residual pitch angle command to the forward thrust engine throttle command.

28. The unmanned aircraft of claim 27, wherein the residual pitch angle command is of a magnitude estimated to provide sufficient forward thrust to account for the determined difference in forward velocity.

29. The unmanned aircraft of claim 24, wherein the processor further performs the operations comprising:

comparing a determined bounded pitch angle for the aircraft to the pitch angle corresponding to the first pitch angle command;

generating a reduced pitch angle command so the resultant aircraft pitch angle does not exceed the bounded pitch angle;

generating a residual pitch angle command based on a difference between the first pitch angle command and the reduced pitch angle command; and

converting the residual pitch angle command into a forward thrust throttle command.

30. The unmanned aircraft of claim 24, wherein the processor further performs the operations comprising:

receiving a velocity signal indicating a determined amount of forward velocity and generating the pitch angle command to provide the determined amount of forward velocity.

31. The unmanned aircraft of claim 30, wherein the determined amount of forward velocity comprises a velocity error between a desired aircraft velocity and an actual aircraft velocity.

32. The unmanned aircraft of claim 30, wherein the velocity signal comprises a velocity error signal.

33. The unmanned aircraft of claim 24, wherein forward thrust engine comprises an internal combustion engine or a motor.

34. The unmanned aircraft of claim 24, wherein vertical thrust engine comprises an internal combustion engine or a motor.

35. The unmanned aircraft of claim 24, wherein the processor further performs the operations comprising converting the second pitch angle command to a VTOL rotor command and providing the VTOL rotor command to the vertical propulsion system.

36. The unmanned aircraft system of claim 24, wherein the unmanned aircraft is a multirotor aircraft and the vertical propulsion system comprises a plurality of vertical thrust engines and corresponding rotors.

37. The unmanned aircraft system of claim 24, wherein the unmanned aircraft is a hybrid multirotor aircraft.

38. The unmanned aircraft system of claim 24, wherein the bounded pitch angle comprises a maximum pitch angle.

39. The unmanned aircraft system of claim 24, wherein the bounded pitch angle comprises a range of pitch angles between a minimum pitch angle and a maximum pitch angle.

40. A method of controlling forward thrust an aircraft comprising, receiving a first pitch angle command;

and generating a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the aircraft.

41. The method of claim 40, further comprising:

comparing a determined bounded pitch angle for the aircraft to the pitch angle corresponding to the first pitch angle command;

generating a reduced pitch angle command so the resultant aircraft pitch angle does not exceed the bounded pitch angle; and

generating the forward thrust engine throttle command based on the reduced pitch angle command.

42. The method of claim 41, wherein generating the forward thrust engine throttle command based on the reduced pitch angle command comprises determining a residual amount of forward thrust needed to compensate for the reduced pitch angle command and generating the forward thrust engine throttle command to at least partially provide the residual amount of forward thrust needed.

43. The method of claim 41, wherein generating the forward thrust engine throttle command based on the reduced pitch angle command comprises:

determining a forward velocity generated by the limited pitch angle command;

determining a difference in forward velocity between forward velocity generated by the limited pitch angle and the determined amount of forward velocity;

generating a residual pitch angle command based on the determined difference in forward velocity; and

converting the residual pitch angle command to the forward thrust engine throttle command.

44. The method of claim 43, wherein the residual pitch angle command is of a magnitude estimated to provide sufficient forward thrust to account for the determined difference in forward velocity.

45. The method of claim 40, further comprising:

comparing a determined bounded pitch angle for the aircraft to the pitch angle corresponding to the first pitch angle command;

generating a reduced pitch angle command so the resultant aircraft pitch angle does not exceed the bounded pitch angle;

generating a residual pitch angle command based on a difference between the first pitch angle command and the reduced pitch angle command; and

converting the residual pitch angle command into a forward thrust throttle command.

46. The method of claim 40, further comprising receiving a velocity signal indicating a determined amount of forward velocity and generating the pitch angle command to provide the determined amount of forward velocity.

47. The method of claim 46, wherein the determined amount of forward velocity comprises a velocity error between a desired aircraft velocity and an actual aircraft velocity.

48. The method of claim 46, wherein the velocity signal comprises a velocity error signal.

49. The method of claim 40, wherein forward thrust engine comprises an internal combustion engine or a motor.

50. The method of claim 40, wherein vertical thrust engine comprises an internal combustion engine or a motor.

51. The method of claim 40, further comprising converting the second pitch angle command to a VTOL rotor command and providing the VTOL rotor command to the vertical propulsion system.