AUTOMATIC FLIGHT ENVELOPE PROTECTION FOR UNINHABITED AIR VEHICLES: METHOD FOR DETERMINING POINT IN FLIGHT ENVELOPE

• US 20040044444A1
• Filed: 08/29/2002
• Published: 03/04/2004
• Est. Priority Date: 08/29/2002
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Kaliski, Martin E., Johnson, Timothy L.
• Granted Patent: US 6,711,477 B1
• Time in Patent Office: Days
• US Class Current: 701/3
• CPC Class Codes: G05D 1/0055 with safety arrangements
• CPC Class Codes: G05D 1/101 specially adapted for aircraft

Abstract

A system and method for detecting if a UAV is operating within its flight envelope. The invention includes defining the flight envelope of the UAV. The operating state of the UAV is identified from a present time to a future elapsed time. The invention determines if the UAV will be within its flight envelope at the end of the elapsed time in the future. It can then command the UAV to maintain operation within the flight envelope if the operating state determined is outside the flight envelope.

Claims

1. A method of detecting if a UAV is operating within its flight envelope, the method comprising:

(a) define the flight envelope of the UAV;

(b) identify the operating state of the UAV from a present time to a future elapsed time; and

(c) determine if the operating state of the UAV will be within the flight envelope at the end of the elapsed time in the future.

2. The method according to claim 1, wherein step (a) comprises:

(i) define the flight envelope as an n-dimensional polytope, where n is at least one of twelve (12) Position or Velocity dimensions of the UAV.

3. The method according to claim 1, wherein step (b) comprises:

(i) measure or approximate the Position or Velocity of the UAV; and

(ii) transform the Position or Velocity of step (i) into the coordinate system of the flight envelope.

4. The method according to claim 1, wherein step (c) comprises performing a computational geometric calculation.

5. The method according to claim 4, wherein the flight envelope is projected onto no more than three dimensions before the computational geometric calculation is performed.

6. The method according to claim 4, wherein the flight envelope is projected onto no more than two dimensions before the computational geometric calculation is performed.

7. The method according to claim 4 wherein step (c) further comprises determining the nearest boundary of the flight envelope to the operating state of the UAV.

8. The method according to claim 4, wherein step (c) further comprises determining the distance in flight envelope coordinates between the operating state of the UAV and the nearest boundary of the flight envelope.

9. The method according to claim 1, wherein the elapsed time in the future is greater than an inner loop time constant of a UAV control system.

10. The method according to claim 1, wherein the elapsed time in the future is shorter than a UAV mission planning time scale.

11. A system for detecting if a UAV is operating within its flight envelope, the system comprising:

means for defining the flight envelope of the UAV;

means for identifying the operating state of the UAV from a present time to a future elapsed time;

means for determining if the UAV will be within its flight envelope at the end of the elapsed time in the future.

12. The system according to claim 11, wherein means for determining if the UAV will be within its flight envelope at the end of the elapsed time in the future comprises means for performing a computational geometric calculation.

13. The system according to claim 11, wherein means for determining if the UAV will be within its flight envelope at the end of the elapsed time in the future comprises means for determining the nearest boundary of the flight envelope to the operating state of the UAV.

14. The system according to claim 11, wherein means for determining if the UAV will be within its flight envelope at the end of the elapsed time in the future comprises means for determining the distance in flight envelope coordinates between the operating state of the UAV and the nearest boundary of the flight envelope.

15. A method of automatic flight envelope protection in a UAV, the method comprising:

(a) define the flight envelope of the UAV;

(b) identify the operating state of the UAV from a present time to a future elapsed time;

(c) determine if the operating state of the UAV will be within the flight envelope at the end of the elapsed time in the future; and

(d) if the operating state determined in step (c) is outside the flight envelope, then command the UAV to maintain operation within the flight envelope.

16. The method according to claim 15, wherein step (c) comprises performing a computational geometric calculation.

17. The method according to claim 16, wherein step (c) further comprises determining the distance in flight envelope coordinates between the operating state of the UAV and the nearest boundary of the flight envelope.

18. The method of claim 17, wherein step (c) further comprises comparing the velocity of the operating state of the UAV to the distance from the nearest boundary.

19. The method according to claim 15, wherein step (d) further comprises limiting the progress of the UAV in at least one dimension of Position or Velocity.

20. The method according to claim 15, further comprising:

(e) determine if the velocity of the operating state of the UAV will intersect the flight envelope; and

(f) if it is determined in step (e) that the velocity of the operating state will not intersect the flight envelope, then step (d) further comprises commanding the UAV to operate so as to reverse the direction of the velocity of the operating state.