Control system for a stopped rotor aircraft

• US 9,975,629 B2
• Filed: 05/18/2017
• Issued: 05/22/2018
• Est. Priority Date: 05/24/2016
• Status: Active Grant

• Current Assignee: Kitty Hawk Corporation
• Original Assignee: Kitty Hawk Corporation
• Inventors: Horn, Gregory Mainland, Vander Lind, Damon
• Primary Examiner(s): Davis, Richard G
• Application Number:
  US15/599,195
• Publication Number:
  US 20170341741A1
• Time in Patent Office: 369 Days
• CPC Class Codes: B64C 2027/8236 including pusher propellers
• CPC Class Codes: B64C 27/14 Direct drive between power plant and rotor hub
• CPC Class Codes: B64C 27/24 with rotor blades fixed in flight to act as lifting surfaces
• CPC Class Codes: B64C 27/26 characterised by provision of fixed wings
• CPC Class Codes: B64C 27/30 with provision for reducing drag of inoperative rotor
• CPC Class Codes: B64C 27/467 Aerodynamic features
• CPC Class Codes: B64C 27/615 including flaps mounted on blades
• CPC Class Codes: B64C 27/82 characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft
• CPC Class Codes: B64C 29/0025 the propellers being fixed relative to the fuselage
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: Y02T 50/30 Wing lift efficiency

Abstract

While an aircraft is mid-flight, a braking start point associated with a stoppable rotor is calculated where the stoppable rotor includes a first and second blade and the stoppable rotor is configured to rotate about a substantially vertical axis. A process to stop the stoppable rotor is started, while the aircraft is mid-flight, when the stoppable rotor reaches the braking start point, where the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward.

Claims

1. A system, comprising:

a processor; and

a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to;

calculate, while an aircraft which includes a stoppable rotor is mid-flight, a braking start point associated with the stoppable rotor, wherein the stoppable rotor includes a first blade and a second blade and the stoppable rotor is configured to rotate about a substantially vertical axis;

start a process to stop the stoppable rotor, while the aircraft which includes the stoppable rotor is mid-flight, when the stoppable rotor reaches the braking start point, wherein the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward;

determine if the stoppable rotor is in an unstable position once the stoppable rotor has stopped; and

in the event it is determined that the stoppable rotor is in an unstable position;

rotate the stoppable rotor at least one more rotation in a regular direction of rotation; and

begin the stopping process to stop the stoppable rotor when the stoppable rotor reaches a second braking start point.

2. The system recited in claim 1, wherein the stopping process includes:

applying an initial amount of torque to the stoppable rotor, wherein the magnitude of the initial amount of torque is strictly less than the magnitude of a maximum amount of torque; and

adjusting an amount of torque applied to the stoppable rotor using feedback.

3. The system recited in claim 1, wherein the stopping process includes:

applying an initial amount of torque to the stoppable rotor, wherein the magnitude of the initial amount of torque is strictly less than the magnitude of a maximum amount of torque; and

adjusting an amount of torque applied to the stoppable rotor using feedback, including by using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor.

4. The system recited in claim 1, wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:

while the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward, adjust a nominal torque of zero applied to the stoppable rotor using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor.

5. The system recited in claim 1, wherein:

the stopping process includes;

applying an initial amount of torque to the stoppable rotor, wherein the magnitude of the initial amount of torque is strictly less than the magnitude of a maximum amount of torque; and

adjusting an amount of torque applied to the stoppable rotor using feedback, including by using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor; and

the memory is further configured to provide the processor with instructions which when executed cause the processor to;

while the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward, adjust a nominal torque of zero applied to the stoppable rotor using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor.

6. The system recited in claim 1, wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:

begin to search for the braking start point once the stoppable rotor has reached a searching start point.

7. The system recited in claim 1, wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:

begin to search for the braking start point once the stoppable rotor has reached a searching start point, wherein a difference between the searching start point and the braking start point is a pre-defined amount.

8. A system comprising:

a processor; and

a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to;

calculate, while an aircraft which includes a stoppable rotor is mid-flight, a braking start point associated with the stoppable rotor, wherein the stoppable rotor includes a first blade and a second blade and the stoppable rotor is configured to rotate about a substantially vertical axis; and

start a process to stop the stoppable rotor, while the aircraft which includes the stoppable rotor is mid-flight, when the stoppable rotor reaches the braking start point, wherein the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward;

determine if the stoppable rotor is in an unstable position before the stoppable rotor comes to a stop; and

in the event it is determined that the stoppable rotor is in an unstable position;

rotate the stoppable rotor at least one more rotation in a regular direction of rotation; and

begin the stopping process to stop the stoppable rotor when the stoppable rotor reaches a second braking start point.

9. A method, comprising:

calculating, while an aircraft which includes a stoppable rotor is mid-flight, a braking start point associated with the stoppable rotor, wherein the stoppable rotor includes a first blade and a second blade and the stoppable rotor is configured to rotate about a substantially vertical axis;

starting a process to stop the stoppable rotor, while the aircraft which includes the stoppable rotor is mid-flight, when the stoppable rotor reaches the braking start point, wherein the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward;

determining if the stoppable rotor is in an unstable position once the stoppable rotor has stopped; and

in the event it is determined that the stoppable rotor is in an unstable position;

rotating the stoppable rotor at least one more rotation in a regular direction of rotation; and

beginning the stopping process to stop the stoppable rotor when the stoppable rotor reaches a second braking start point.

10. The method recited in claim 9, wherein the stopping process includes:

applying an initial amount of torque to the stoppable rotor, wherein the magnitude of the initial amount of torque is strictly less than the magnitude of a maximum amount of torque; and

adjusting an amount of torque applied to the stoppable rotor using feedback.

11. The method recited in claim 9, wherein the stopping process includes:

applying an initial amount of torque to the stoppable rotor, wherein the magnitude of the initial amount of torque is strictly less than the magnitude of a maximum amount of torque; and

adjusting an amount of torque applied to the stoppable rotor using feedback, including by using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor.

12. The method recited in claim 9 further comprising:

while the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward, adjusting a nominal torque of zero applied to the stoppable rotor using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor.

13. The method recited in claim 9, wherein:

the stopping process includes;

applying an initial amount of torque to the stoppable rotor, wherein the magnitude of the initial amount of torque is strictly less than the magnitude of a maximum amount of torque; and

adjusting an amount of torque applied to the stoppable rotor using feedback, including by using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor; and

the method further includes;

while the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward, adjusting a nominal torque of zero applied to the stoppable rotor using a proportional-integral-derivative (PID) controller which uses a rotational angle associated with the stoppable rotor and an angular rate associated with the stoppable rotor.

14. The method recited in claim 9 further comprising:

beginning to search for the braking start point once the stoppable rotor has reached a searching start point.

15. The method recited in claim 9 further comprising:

begin to search for the braking start point once the stoppable rotor has reached a searching start point, wherein a difference between the searching start point and the braking start point is a pre-defined amount.

16. A method comprising:

calculating, while an aircraft which includes a stoppable rotor is mid-flight, a braking start point associated with the stoppable rotor, wherein the stoppable rotor includes a first blade and a second blade and the stoppable rotor is configured to rotate about a substantially vertical axis;

starting a process to stop the stoppable rotor, while the aircraft which includes the stoppable rotor is mid-flight, when the stoppable rotor reaches the braking start point, wherein the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward;

determining if the stoppable rotor is in an unstable position before the stoppable rotor comes to a stop; and

in the event it is determined that the stoppable rotor is in an unstable position;

rotating the stoppable rotor at least one more rotation in a regular direction of rotation; and

beginning the stopping process to stop the stoppable rotor when the stoppable rotor reaches a second braking start point.

17. A computer program product, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:

calculating, while an aircraft which includes a stoppable rotor is mid-flight, a braking start point associated with the stoppable rotor, wherein the stoppable rotor includes a first blade and a second blade and the stoppable rotor is configured to rotate about a substantially vertical axis;

starting a process to stop the stoppable rotor, while the aircraft which includes the stoppable rotor is mid-flight, when the stoppable rotor reaches the braking start point, wherein the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward;

determining if the stoppable rotor is in an unstable position once the stoppable rotor has stopped; and

in the event it is determined that the stoppable rotor is in an unstable position;

rotating the stoppable rotor at least one more rotation in a regular direction of rotation; and

beginning the stopping process to stop the stoppable rotor when the stoppable rotor reaches a second braking start point.

18. A computer program product, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:

calculating, while an aircraft which includes a stoppable rotor is mid-flight, a braking start point associated with the stoppable rotor, wherein the stoppable rotor includes a first blade and a second blade and the stoppable rotor is configured to rotate about a substantially vertical axis;

starting a process to stop the stoppable rotor, while the aircraft which includes the stoppable rotor is mid-flight, when the stoppable rotor reaches the braking start point, wherein the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward;

determining if the stoppable rotor is in an unstable position before the stoppable rotor comes to a stop; and

in the event it is determined that the stoppable rotor is in an unstable position;

rotating the stoppable rotor at least one more rotation in a regular direction of rotation; and

beginning the stopping process to stop the stoppable rotor when the stoppable rotor reaches a second braking start point.