Aircraft collision sense and avoidance system and method

• US 7,876,258 B2
• Filed: 03/13/2006
• Issued: 01/25/2011
• Est. Priority Date: 03/13/2006
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Witt, Christian C., Abraham, Michael R., Musial, Christopher J., Yelton, Dennis J., Sanders-Reed, John N.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US11/374,807
• Publication Number:
  US 20070210953A1
• Time in Patent Office: 1,779 Days
• Field of Search: 342/29, 342/179, 342/159, 342/140
• US Class Current: 342/29
• CPC Class Codes: G08G 5/0069 specially adapted for an unmanned aircraft
• CPC Class Codes: G08G 5/045 Navigation or guidance aids, e.g. determination of anti-collision manoeuvers radar or analogous systems specially adapted for anti-collision between aircraft G01S13/933

Abstract

A collision sense and avoidance system and method and an aircraft, such as an Unmanned Air Vehicle (UAV) and/or Remotely Piloted Vehicle (RPV), including the collision sense and avoidance system. The collision sense and avoidance system includes an image interrogator identifies potential collision threats to the aircraft and provides maneuvers to avoid any identified threat. Motion sensors (e.g., imaging and/or infrared sensors) provide image frames of the surroundings to a clutter suppression and target detection unit that detects local targets moving in the frames. A Line Of Sight (LOS), multi-target tracking unit, tracks detected local targets and maintains a track history in LOS coordinates for each detected local target. A threat assessment unit determines whether any tracked local target poses a collision threat. An avoidance maneuver unit provides flight control and guidance with a maneuver to avoid any identified said collision threat.

Claims

1. An image interrogator identifying and avoiding potential collision threats, said image interrogator comprising:

a clutter suppression and target detection unit detecting moving targets from local images;

a Line Of Sight (LOS), multi-target tracking unit tracking detected said targets from each target'"'"'s focal plane track and from attitude;

a threat assessment unit correlating a LOS track for said targets to construct a three-dimensional (3D) relative trajectory for each of said targets and determining from said 3D relative trajectories whether any tracked target poses a collision threat; and

an avoidance maneuver unit determining a maneuver to avoid any identified said collision threat, wherein said image interrogator is vehicle mountable, and when mounted on an unmanned vehicle guiding said unmanned vehicle in unchaperoned travel in 3D space.

2. An image interrogator as in claim 1, wherein said image interrogator further comprises a target track history, said LOS, multi-target tracking unit maintaining a track history in each target'"'"'s focal plane for each said tracked target in said target track history.

3. An image interrogator as in claim 1, wherein said threat assessment unit determines whether each said tracked target poses a collision threat based on a respective track history in each respective target'"'"'s focal plane.

4. An image interrogator as in claim 1, wherein said threat assessment unit categorizes each said tracked target as either not on a collision course or on a possible collision course without determining the range to each said tracked target.

5. An image interrogator as in claim 4, wherein said each tracked target categorized as on a collision course maintains a track at a constant angle to a host aircraft containing said image interrogator.

6. An image interrogator as in claim 4, wherein said threat assessment unit further categorizes each said tracked target categorized as on a possible collision course as either a likely collision threat or not a likely collision threat.

7. An image interrogator as in claim 6, wherein waxing said targets on a possible collision are categorized as likely collision threats and waning said targets on a possible collision are categorized as not likely collision threats.

8. An image interrogator as in claim 1, wherein said image interrogator is contained in a host aircraft, and said avoidance maneuver unit selects a maneuver to avoid a collision for said host aircraft, said maneuver being selected based on trajectories of all said targets and avoiding collision with said all targets, said host aircraft being guided in pilotless unchaperoned flight in air space.

9. An image interrogator as in claim 1, wherein said image interrogator comprises at least one Field Programmable Gate Array (FPGA) processor in an aircraft and containing said image interrogator.

10. An aircraft comprising:

a plurality of motion sensors sensing local images;

an image interrogator guiding said aircraft in unchaperoned pilotless flight, said image interrogator comprising;

a clutter suppression and target detection unit detecting moving targets from said local images,

a Line Of Sight (LOS), multi-target tracking unit, tracking detected said targets from each target'"'"'s focal plane track and from the aircraft attitude,

a target track history, said LOS, multi-target tracking unit maintaining a track history in LOS coordinates for each detected target in said target track history;

a threat assessment unit correlating a LOS track for said targets to construct a three-dimensional (3D) relative trajectory for each of said targets and determining from said 3D relative trajectories whether any tracked target poses a collision threat, and

an avoidance maneuver unit determining a maneuver to avoid any identified said collision threat; and

a flight control and guidance unit receiving avoidance maneuvers from said avoidance maneuver unit and selectively executing said received avoidance maneuvers.

11. An aircraft as in claim 10, wherein said threat assessment unit determines whether each said tracked target poses a collision threat based on a respective target track history without determining the range to each said tracked target.

12. An aircraft as in claim 11, wherein said threat assessment unit categorizes each said tracked target as either not on a collision course or on a possible collision course with said aircraft, and each said tracked target categorized as on a collision course maintains a track at a constant angle to said aircraft.

13. An aircraft as in claim 11, wherein said threat assessment unit categorizes each said tracked target as either not on a collision course or on a possible collision course with said aircraft, each said tracked target categorized as on a possible collision further categorized as either a likely collision threat or not a likely collision threat to said aircraft.

14. An aircraft as in claim 13, wherein waxing said targets are categorized as likely collision threats and waning said targets are categorized as not likely collision threats.

15. An aircraft as in claim 10, wherein said image interrogator is implemented in at least one Field Programmable Gate Array processor fixed to said aircraft.

16. An aircraft as in claim 10, wherein said avoidance maneuver unit selects a maneuver for said aircraft based on trajectories of all said targets and avoiding collision with said all targets.

17. An aircraft as in claim 10, wherein said plurality of sensors comprises a plurality of imaging sensors.

18. An aircraft as in claim 10, wherein said plurality of sensors comprises a plurality of infrared sensors.

19. An aircraft as in claim 10, wherein said aircraft is an Unmanned Air Vehicle (UAV) flying unchaperoned.

20. A method of detecting and tracking targets by an airborne vehicle, the vehicle having a plurality of imaging sensors, said method comprising:

providing a module for angles only imaging, said module receiving inputs from the plurality of imaging sensors on the vehicle, the module having logic for processing a plurality of images from the plurality of imaging sensors;

processing the plurality of images to detect targets against cluttered backgrounds; and

creating time histories in the module from each target'"'"'s focal plane track and from the vehicle attitude, the time histories being of the relative motion of the targets in Line Of Sight (LOS) coordinates;

wherein the module comprises a field programmable gate array processor and guides said vehicle in, unchaperoned, unmanned flight.

21. The method of claim 20, wherein the module is provided on an unmanned air vehicle, providing a threat assessment by correlating a LOS track for said targets to construct a three-dimensional (3D) relative trajectory for each of said targets and determining from said 3D relative trajectories whether any tracked target poses a collision threat to guide said unmanned vehicle in pilotless unchaperoned flight.

22. The method of claim 20, wherein the module is provided on a manned vehicle, providing a threat assessment by correlating a LOS track for said targets to construct a three-dimensional (3D) relative trajectory for each of said targets and determining from said 3D relative trajectories whether any tracked target poses a collision threat to said manned vehicle.

23. The method of claim 20, wherein processing the plurality of images comprises using single frame processing and a convolution with an Optical Point Spread Function.

24. The method of claim 20, wherein processing the plurality of images comprises using a multi-frame moving target detection algorithm.

25. A method of detecting and avoiding target collision by an airborne vehicle, the vehicle having a plurality of imaging sensors, said method comprising:

providing a module for angles only imaging, said module receiving inputs from the plurality of imaging sensors on the vehicle, the module having logic for processing a plurality of images from the plurality of imaging sensors, the module comprising a field programmable gate array processor;

processing the plurality of images to detect targets against cluttered backgrounds;

creating from each target'"'"'s focal plane track and from the aircraft attitude time histories of the relative motion of the targets in Line Of Sight (LOS) coordinates;

assessing a level of collision threat with one or more of the targets by correlating a LOS track for said targets to construct a three-dimensional (3D) relative trajectory for each of said targets and determining from said 3D relative trajectories whether any tracked target poses a collision threat; and

commanding the vehicle to avoid collision with the one or more targets, the vehicle flying unchaperoned in air space.

26. The method of claim 25, wherein assessing the level of collision threat comprises:

selecting a target from said detected targets;

determining a 3D trajectory for said selected target from the selected target'"'"'s focal plane track in LOS coordinates;

determining whether said 3D trajectory passes said airborne vehicle by more than a selected minimum safe distance;

selecting another target from said detected targets; and

returning to the step of determining a 3D trajectory for said selected target.

27. The method of claim 26, wherein whenever said 3D trajectory for said selected target is determined to be passing said airborne vehicle by less than said selected minimum safe distance, said target is identified as a collision threat.

28. The method of claim 26, wherein determining said 3D trajectory comprises

determining a line of sight (LOS) trajectory from said selected target'"'"'s focal plane track for said selected target to said airborne vehicle;

and

determining an apparent range change between said selected target and said airborne vehicle.

29. The method of claim 27 providing detect and avoid capability to said airborne vehicle and, wherein a target speed-to-size ratio is determined from said 3D trajectory and determining whether said trajectory for said selected target is passing said airborne vehicle by less than said selected minimum safe distance comprises comparing determined said target speed-to-size ratio results with speed-to-size ratios and probabilities of known real collision threats.

30. The method of claim 25, wherein commanding the vehicle to avoid collision comprises:

retrieving trajectories for all detected said targets;

determining a minimum safe distance for said airborne vehicle from each target identified as collision threat; and

determining a maneuver for said airborne vehicle to avoid all detected said targets.

31. The method of claim 30 providing said airborne vehicle with a capability of pilotless unchaperoned flight and wherein a trajectory for said airborne vehicle is determined before determining said minimum safe distance.

32. The method of claim 31 wherein determining said maneuver comprises:

determining maneuvering constraints for said airborne vehicle, said maneuvering constraints constraining said airborne vehicle from executing maneuvers exceeding defined vehicle operating limits; and

determining an evasive maneuver to avoid each said collision threat for said airborne vehicle within said maneuvering constraints.