Granted Patent B2

US 9,975,629 · App. 15/599,195 · Granted May 22, 2018

Inventors: Gregory Mainland Horn (Mountain View, CA); Damon Vander Lind (Oakland, CA)

Assignee: Kitty Hawk Corporation

B64C27/24B64C27/26B64C27/82B64C29/0025G05B11/42B64C2027/8236

Abstract

Claims (74)

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.

Assignments (8)

Continuity (2)