Spatial avoidance method and apparatus

• US 20030014165A1
• Filed: 06/20/2002
• Published: 01/16/2003
• Est. Priority Date: 12/21/1999
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Baker, Brian C, Paynter, Scott J
• Granted Patent: US 6,785,610 B2
• Time in Patent Office: Days
• US Class Current: 701/3
• CPC Class Codes: G05D 1/104 involving a plurality of aircrafts, e.g. formation flying traffic control systems for aircraft G08G5/00
• CPC Class Codes: G05D 1/107 specially adapted for missiles

Abstract

An obstacle avoidance system, apparatus, and method is described suitable for use on autonomously guided or man-in-the-loop guided vehicles such as aircraft, missiles, cars, and other types of vehicles. The system provides guidance instructions in the situation where the vehicle encounters an obstacle either directly or indirectly in its path while traveling to a desired destination or where vehicles are traveling in formation. The system can be applied not only to obstacle avoidance but also to trajectory shaping by defining obstacles, operational boundaries and/or threats which influence the trajectory of the vehicle.

Claims

1. A method of maneuvering a vehicle towards a destination in the presence of at least one obstacle, comprising the steps of:

establishing a nominal guidance direction for said vehicle;

establishing a nominal obstacle avoidance direction based on said obstacle;

determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction.

2. A method in accordance with claim 1, wherein said nominal obstacle avoidance direction is a geometric based avoidance vector determined based on a defined geometric boundary surrounding said obstacle.

3. A method in accordance with claim 1, further comprising the steps of:

defining a geometric boundary surrounding said obstacle; and

determining whether said vehicle is outside of said geometric boundary or inside of said geometric boundary.

4. A method in accordance with claim 3, wherein, in the case that said vehicle is outside of said geometric boundary, said nominal guidance direction for said vehicle is a direction substantially towards said destination.

5. A method in accordance with claim 2, wherein, in the case that said vehicle is inside of said geometric boundary, said nominal guidance direction for said vehicle is an anti-intercept direction between said vehicle and said obstacle.

6. A method in accordance with claim 2, further comprising the step of determining a distance between said vehicle and said obstacle.

7. A method in accordance with claim 6, wherein said step of determining a vehicle steering direction is further based on said distance.

8. A method in accordance with claim 7, wherein said vehicle steering direction is further based on a distance-based field element.

9. A method in accordance with claim 7, further comprising the step of determining a range of influence of said obstacle and wherein, in the case where said vehicle is beyond the range of influence of said obstacle, said vehicle steering direction is determined without regard to the presence of said obstacle.

10. A method in accordance with claim 7, further comprising the step of determining a range of influence of said obstacle and wherein, in the case where said vehicle is within the range of influence of said obstacle, said vehicle steering direction is determined based on the presence of said obstacle.

11. A method in accordance with claim 1, wherein said steering direction is determined by blending together said nominal guidance direction and said obstacle avoidance direction based on a blending ratio.

12. A method in accordance with claim 11, wherein said blending ratio is a function.

13. A method in accordance with claim 12, wherein said blending ratio is a function of a distance separating said vehicle and said obstacle.

14. A method in accordance with claim 11, wherein said steering direction is determined in accordance with a function of the form:

D_STEERING=F1*D_GUIDANCE+F2*D_AVOIDANCE;

where;

D_GUIDANCE is a vector with a direction in said nominal guidance direction;

D_AVOIDANCE is a vector with a direction in said nominal obstacle avoidance direction;

D_STEERING is said vehicle steering direction;

F1 is a first continuous function; and

F2 is a second continuous function.

15. A method in accordance with claim 14, wherein F2≈

1−

F1.

16. A method in accordance with claim 14, further comprising the step of steering said vehicle towards said steering direction;

and

wherein said nominal obstacle avoidance direction is based on a relative position of said vehicle to said obstacle, and wherein said steps of establishing a nominal guidance direction towards said destination, establishing a nominal obstacle avoidance direction based on said obstacle, determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction, and steering said vehicle towards said steering direction are repeated a plurality of times as said vehicle travels.

17. A method in accordance with claim 1, wherein:

said vehicle travels towards said destination in the presence of a plurality of obstacles;

said step of establishing a nominal obstacle avoidance direction includes establishing a nominal obstacle avoidance direction for each of said obstacles; and

said step of determining a vehicle steering direction includes determining a vehicle steering direction based on said guidance direction and each of said obstacle avoidance directions.

18. A method in accordance with claim 2, further comprising the step of determining whether said vehicle is approaching said obstacle or whether said vehicle is receding from said obstacle.

19. A method in accordance with claim 18, wherein said step of determining a vehicle steering direction includes determining a vehicle steering direction based on a result of said step of determining whether said vehicle is approaching said obstacle or whether said vehicle is receding from said obstacle.

20. A method in accordance with claim 1, further comprising the step outputting a steering control signal effective to steer said vehicle in accordance with said steering direction.

21. A method in accordance with claim 1, further comprising the step of displaying a steering command in accordance with said steering direction.

22. A method of maneuvering a vehicle towards a destination in the presence of at least one obstacle, comprising the steps of:

establishing a nominal guidance direction for said vehicle;

establishing a geometric boundary surrounding said obstacle;

determining a distance between said vehicle and said obstacle;

determining whether said vehicle is inside of said geometric boundary or outside of said geometric boundary;

based on said step of determining whether said vehicle is inside of said geometric boundary or outside of said geometric boundary, establishing;

in the case where said vehicle is inside of said geometric boundary, said nominal guidance direction for said vehicle is a direction substantially towards the destination, and

in the case where said vehicle is inside of said geometric boundary, said nominal guidance direction for said vehicle is an anti intercept direction between said vehicle and said obstacle; and

determining a vehicle steering direction based on said guidance direction, an applicable one of said nominal guidance direction based on a direction substantially towards said destination and said nominal guidance direction based on an anti-intercept direction, said distance, and any distance-based field element.

24. An apparatus of claim 23, further comprising:

an autopilot for receiving said vehicle steering direction and steering said vehicle toward said vehicle steering direction.

28. A guidance processor in accordance with claim 27, wherein said nominal obstacle avoidance direction is a geometric based avoidance vector determined based on a defined geometric boundary surrounding said obstacle.

29. A guidance processor in accordance with claim 27, further comprising:

a device for defining a geometric boundary surrounding said obstacle; and

a device for determining whether said vehicle is outside of said geometric boundary or inside of said geometric boundary.

30. A guidance processor in accordance with claim 29, wherein, in the case that said vehicle is outside of said geometric boundary, said nominal guidance direction for said vehicle is a direction substantially towards said destination.

31. A guidance processor in accordance with claim 29, wherein, in the case that said vehicle is inside of said geometric boundary, said nominal guidance direction for said vehicle is an anti-intercept direction between said vehicle and said obstacle.

32. A guidance processor in accordance with claim 28, further comprising:

a device for determining a distance between said vehicle and said obstacle.

33. A guidance processor in accordance with claim 32, wherein said device for determining a vehicle steering direction further determines said vehicle steering direction based on said distance.

34. A guidance processor in accordance with claim 33, wherein said device for determining a vehicle steering direction further determines said vehicle steering direction based on a distance-based field element.

35. A guidance processor in accordance with claim 33, further comprising:

a device for determining a range of influence of said obstacle and wherein, in the case where said vehicle is beyond the range of influence of said obstacle, said device for determining a vehicle steering direction further determines said vehicle steering direction without regard to the presence of said obstacle.

36. A guidance processor in accordance with claim 33, further comprising:

a device for determining a range of influence of said obstacle and wherein, in the case where said vehicle is within the range of influence of said obstacle, said device for determining a vehicle steering direction further determines said vehicle steering direction based on the presence of said obstacle.

37. A guidance processor in accordance with claim 27, wherein said device for determining a vehicle steering direction determines said steering direction by blending together said nominal guidance direction and said obstacle avoidance direction based on a blending ratio.

38. A guidance processor in accordance with claim 37, wherein said blending ratio is a function.

39. A guidance processor in accordance with claim 38, wherein said blending ratio is a function of a distance separating said vehicle and said obstacle.

40. A guidance processor in accordance with claim 37, wherein said device for determining a vehicle steering direction determines said steering direction in accordance with a function of the form:

D_STEERING=F1*D_GUIDANCE+F2*D_AVOIDANCE;

where;

D_GUIDANCE is a vector with a direction in said nominal guidance direction;

D_AVOIDANCE is a vector with a direction in said nominal obstacle avoidance direction;

D_STEERING is said vehicle steering direction;

F1 is a first continuous function; and

F2 is a second continuous function.

41. A guidance processor in accordance with claim 40, wherein F2≈

1−

F1.

42. A guidance processor in accordance with claim 40, further comprising:

a device for steering said vehicle towards said steering direction; and

wherein said device for determining a nominal guidance direction for said vehicle determines said nominal obstacle avoidance direction based on a relative position of said vehicle to said obstacle, and wherein device for determining a nominal guidance direction for said vehicle, said device for determining a nominal obstacle avoidance direction based on said obstacle, and said device for determining a vehicle steering direction each continually update its corresponding direction as said vehicle travels.

43. A guidance processor in accordance with claim 27, wherein:

said vehicle travels towards said destination in the presence of a plurality of obstacles;

said device for determining a nominal obstacle avoidance direction includes establishing a nominal obstacle avoidance direction determines a nominal obstacle avoidance direction for each of said obstacles; and

said device for determining a vehicle steering direction determines a vehicle steering direction based on said guidance direction and each of said obstacle avoidance directions.

44. A guidance processor in accordance with claim 28, further comprising:

a device for determining whether said vehicle is approaching said obstacle or whether said vehicle is receding from said obstacle.

45. A guidance processor in accordance with claim 44, wherein said device for determining a vehicle steering direction determines a vehicle steering direction based on an output from said device for determining whether said vehicle is approaching said obstacle or whether said vehicle is receding from said obstacle.

46. A guidance processor in accordance with claim 27, further comprising:

a device for outputting a steering control signal to steer said vehicle in accordance with said steering direction.

47. A guidance processor in accordance with claim 27, further comprising:

a device for displaying a steering command in accordance with said steering direction.

49. A memory device in accordance with claim 48, wherein said nominal obstacle avoidance direction is a geometric based avoidance vector determined based on a defined geometric boundary surrounding said obstacle.

50. A memory device in accordance with claim 48, further comprising encoded instructions executable by the autopilot controller for:

defining a geometric boundary surrounding said obstacle; and

determining whether said vehicle is outside of said geometric boundary or inside of said geometric boundary.

51. A memory device in accordance with claim 50, wherein, in the case that said vehicle is outside of said geometric boundary, said nominal guidance direction for said vehicle is a direction substantially towards said destination.

52. A memory device in accordance with claim 50, wherein, in the case that said vehicle is inside of said geometric boundary, said nominal guidance direction for said vehicle is an anti-intercept direction between said vehicle and said obstacle.

53. A memory device in accordance with claim 49, further comprising encoded instructions executable by the guidance processor for:

receiving information indicative of a distance between said vehicle and said obstacle.

54. A memory device in accordance with claim 53, wherein said encoded instructions for determining a vehicle steering direction further determine said steering direction based on said distance.

55. A memory device in accordance with claim 54, wherein said encoded instructions for determining a vehicle steering direction further determine said vehicle steering direction based on a distance-based field element.

56. A memory device in accordance with claim 54, further comprising encoded instructions executable by the guidance processor for:

determining a range of influence of said obstacle; and

wherein, in the case where said vehicle is beyond the range of influence of said obstacle, said encoded instructions for determining a vehicle steering direction further determine said vehicle steering direction without regard to the presence of said obstacle.

57. A memory device in accordance with claim 54, further comprising encoded instructions executable by the guidance processor for:

determining a range of influence of said obstacle and wherein, in the case where said vehicle is within the range of influence of said obstacle, said encoded instructions for determining a vehicle steering direction further determine said vehicle steering direction based on the presence of said obstacle.

58. A memory device in accordance with claim 48, wherein said encoded instructions for determining a vehicle steering direction determine said steering direction by blending together said nominal guidance direction and said obstacle avoidance direction based on a blending ratio.

59. A memory device in accordance with claim 58, wherein said blending ratio is a function.

60. A memory device in accordance with claim 59, wherein said blending ratio is a function of a distance separating said vehicle and said obstacle.

61. A memory device in accordance with claim 58, wherein said steering direction is determined in accordance with a function of the form:

D_STEERING=F1*D_GUIDANCE+F2*D_AVOIDANCE;

where;

D_GUIDANCE is a vector with a direction in said nominal guidance direction;

D_AVOIDANCE is a vector with a direction in said nominal obstacle avoidance direction;

D_STEERING is said vehicle steering direction;

F1 is a first continuous function; and

F2 is a second continuous function.

62. A memory device in accordance with claim 61, wherein F2≈

1−

F1.

63. A memory device in accordance with claim 61, further comprising encoded instructions executable by the guidance processor for:

outputting a steering signal for steering said vehicle towards said steering direction; and

wherein said encoded instructions for determining a nominal obstacle avoidance direction determine said nominal obstacle avoidance direction based on a relative position of said vehicle to said obstacle, and wherein said memory further comprises encoded instructions to execute said instructions for establishing a nominal guidance direction towards said destination, establishing a nominal obstacle avoidance direction based on said obstacle, determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction, and outputting a steering signal for steering said vehicle towards said steering direction a plurality of times as said vehicle travels.

64. A memory device in accordance with claim 48, wherein:

said vehicle travels towards said destination in the presence of a plurality of obstacles;

said encoded instructions for establishing a nominal obstacle avoidance direction include encoded instructions for establishing a nominal obstacle avoidance direction for each of said obstacles; and

said encoded instructions for determining a vehicle steering direction includes encoded instructions for determining a vehicle steering direction based on said guidance direction and each of said obstacle avoidance directions.

65. A memory device in accordance with claim 49, further comprising encoded instructions executable by the guidance processor for:

determining whether said vehicle is approaching said obstacle or whether said vehicle is receding from said obstacle.

66. A memory device in accordance with claim 65, wherein said encoded instructions for determining a vehicle steering direction includes encoded instructions for determining a vehicle steering direction based on an output of said encoded instructions for determining whether said vehicle is approaching said obstacle or whether said vehicle is receding from said obstacle.

67. A memory device in accordance with claim 48, further comprising encoded instructions executable by the guidance processor for:

outputting a steering control signal effective to steer said vehicle in accordance with said steering direction.

68. A memory device in accordance with claim 48, further comprising encoded instructions executable by the guidance processor for:

outputting a steering display command in accordance with said steering direction for indicating a direction for steering said vehicle.

23. An apparatus for maneuvering a vehicle towards a destination in the presence of at least one obstacle, comprising:

a controller having a memory;

a means for inputting a nominal guidance direction for said vehicle into said memory;

a computer for computing a nominal obstacle avoidance direction based on said obstacle, and for computing a vehicle steering direction based on said guidance direction and said obstacle avoidance direction.

25. A method for maneuvering a first vehicle in the presence of a second vehicle, comprising the steps of:

establishing a nominal guidance direction for each of said first and said second vehicles;

establishing a nominal obstacle avoidance direction for said first vehicle with respect to said second vehicle;

determining a steering direction for said first vehicle based on said guidance direction of said first vehicle and said obstacle avoidance direction.

26. A method for maneuvering a first vehicle in relation to a second vehicle, comprising the steps of:

establishing a first repulsive boundary around said second vehicle;

establishing a first attractive boundary around said first repulsive boundary, said first repulsive boundary and said first attractive boundary defining an interactive region therebetween;

computing a steering direction for said first vehicle such that

when said first vehicle is outside said first attractive boundary, said first vehicle is directed toward said second vehicle,

when said first vehicle is within said first repulsive boundary, said first vehicle is directed away from said second vehicle, and

when said first vehicle is within said interactive region, said first vehicle is directed either toward or away from said second vehicle based on a weighted function.

27. A guidance processor for maneuvering a vehicle towards a destination in the presence of at least one obstacle, comprising:

a device for determining a nominal guidance direction for said vehicle;

a device for determining a nominal obstacle avoidance direction based on said obstacle;

a device for determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction.

48. A memory device for use with a guidance processor for maneuvering a vehicle towards a destination in the presence of at least one obstacle, said memory device comprising encoded instructions executable by the guidance processor for:

establishing a nominal guidance direction for said vehicle;

establishing a nominal obstacle avoidance direction based on said obstacle;

determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction.

69. Computer executable software for use with a guidance processor for maneuvering a vehicle towards a destination in the presence of at least one obstacle, comprising:

means for determining a nominal guidance direction for said vehicle;

means for determining a nominal obstacle avoidance direction based on said obstacle;

means for determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction.

70. An autopilot controller for maneuvering a vehicle towards a destination in the presence of at least one obstacle, comprising:

a device for determining a nominal guidance direction for said vehicle;

a device for determining a nominal obstacle avoidance direction based on said obstacle;

a device for determining a vehicle steering direction based on said guidance direction and said obstacle avoidance direction.

71. An autopilot controller in accordance with claim 70, wherein said nominal obstacle avoidance direction is a geometric based avoidance vector determined based on a defined geometric boundary surrounding said obstacle.

72. An autopilot controller in accordance with claim 70, wherein said device for determining a vehicle steering direction determines said steering direction by blending together said nominal guidance direction and said obstacle avoidance direction based on a blending ratio.

73. An autopilot controller in accordance with claim 72, wherein said blending ratio is a function.

74. An autopilot controller in accordance with claim 73, wherein said blending ratio is a function of a distance separating said vehicle and said obstacle.

75. An autopilot controller in accordance with claim 72, wherein said device for determining a vehicle steering direction determines said steering direction in accordance with a function of the form:

D_STEERING=F1*D_GUIDANCE+F2*D_AVOIDANCE;

where;

D_GUIDANCE is a vector with a direction in said nominal guidance direction;

D_AVOIDANCE is a vector with a direction in said nominal obstacle avoidance direction;

D_STEERING is said vehicle steering direction;

F1 is a first continuous function; and

F2 is a second continuous function.

76. An autopilot controller in accordance with claim 75, wherein F2≈

1−

F1.

77. An autopilot controller in accordance with claim 75, further comprising:

a device for steering said vehicle towards said steering direction; and

wherein said device for determining a nominal guidance direction for said vehicle determines said nominal obstacle avoidance direction based on a relative position of said vehicle to said obstacle, and wherein device for determining a nominal guidance direction for said vehicle, said device for determining a nominal obstacle avoidance direction based on said obstacle, and said device for determining a vehicle steering direction each continually update its corresponding direction as said vehicle travels.