Apparatus and method for providing accurate boundaries of predicted areas of danger for collision avoidance

• US 6,408,248 B1
• Filed: 07/11/2000
• Issued: 06/18/2002
• Est. Priority Date: 07/11/2000
• Status: Expired due to Term

• Current Assignee: Litton Marine Systems Inc., Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Wood, Thomas E., Yancey, John F. Jr.
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/613,641
• Time in Patent Office: 707 Days
• Field of Search: 701/301, 701/300, 701/302, 342/104, 342/126, 342/107, 342/41, 342/455, 342/452, 342/453, 342/458, 340/903, 340/435, 340/556, 340/961, 340/436
• US Class Current: 701/301
• CPC Class Codes: B60Q 9/008 for anti-collision purposes
• CPC Class Codes: G01S 13/937 of marine craft
• CPC Class Codes: G08G 3/02 Anti-collision systems

Abstract

A true predicted area of danger providing a preselected miss distance between an intruding vehicle and own ship is provided. A miss distance circle, having a radius equal to the desired miss distance, is generated about the initial position of the intruding vehicle and the relative coordinates and distances from own vehicle of selected points on this miss distance circle are determined. Points of own vehicle intercept of these selected points are established and a smooth curve is drawn through these points to provide the boundary of the predicted area of danger.

Claims

1. A method for predicting an area of danger for a first vehicle in the vicinity of a second vehicle, the first vehicle having a velocity and the second vehicle having a velocity and initial relative position to said first vehicle comprising the steps of:

establishing a miss distance circle having a radius equal to a desired miss distance about an initial position of said second vehicle;

projecting said miss distance circle to establish a boundary for a predicted area of danger, which avoided assures that said first vehicle will pass said second vehicle no closer than said miss distance.

2. The method of claim 1 wherein said projecting step includes the steps of:

selecting points on said miss distance circle, thereby providing selected points;

projecting said selected points to locations of intercept with said first vehicle; and

smoothly connecting said locations to establish said boundary.

3. The method of claim 2 wherein said projecting step includes the steps of:

establishing coordinates of said selected points relative to said first vehicle, thereby providing selected points coordinates;

imparting said second vehicle velocity to said selected points; and

utilizing said second vehicle velocity imparted to said selected points, said first vehicle velocity, and said selected points coordinates to determine said intercept locations.

4. The method of claim 3 wherein said utilizing step includes the steps of:

determining intercept time between said first vehicle and each selected point;

multiplying components of said second vehicle velocity by said intercept time for each selected point to provide respective coordinate changes for each selected point due to distance traversed over said intercept time; and

a adding said respective coordinate changes to corresponding coordinates of said selected points, thereby establishing said intercept locations.

5. The method of claim 4 wherein points selected in said selecting points step are equally spaced on said miss distance circle.

6. The method of claim 4 further including the steps of:

analyzing said intercept time to determine boundaries of feasible region within said miss distance circle; and

wherein said selecting points step selects points on said miss distance circle only within said feasible region.

7. The method of claim 6 wherein said selecting points step includes the steps of:

determining the feasibility angular range subtended from said first vehicle by said feasibility region;

dividing solid angular region into equal angle segments; and

projecting edges of said angle segments to crossing points with said miss distance circle, said crossing points being said selected points.

8. The method of claim 6 wherein points selected in said selecting points step are equally spaced within said feasibility region on said miss distance circle.

9. The method of claim I further including the steps of:

determining relative velocity of said second vehicle to said first vehicle;

analyzing said relative velocity to determine boundaries of feasible region within said miss distance circle; and

selecting points on said miss distance circle only within said feasible region.

10. The method of claim 9 wherein said selecting points step includes the steps of:

determining feasibility angular range subtended from said first vehicle by said feasibility region;

dividing said angular range into equal angle segments; and

projecting edges of said angle segments to crossing points with said miss distance circle, said crossing points being said selected points.

11. The method of claim 9 wherein points selected in said selecting points step are equally spaced within said feasibility range on said miss distance circle.

12. An apparatus for predicting an area of danger for a first vehicle in the vicinity of a second vehicle, the first vehicle having a velocity and the second vehicle having a velocity and an initial relative position to the first vehicle comprising:

a miss distance circle generator for providing signals representative of a desired miss distance circle about said initial relative position of said second vehicle; and

a mapper coupled to receive said miss distance circle representative signals for providing signals representative of a boundary of a predicted area of danger, which avoided assures that said first vehicle will pass said second vehicle no closer than said miss distance.

13. An apparatus in accordance with claim 12 wherein said mapper includes:

a point selector for selecting points on said miss distance circle and supplying signals representative of selected points;

a locator coupled to said point selector and to receive signals representative of said first and second vehicle velocities for providing signals representative of locations of intercept between said first vehicle and said selected points; and

a boundary generator coupled to receive said location representative signals for providing signals representative of a smooth boundary through said intercept locations.

14. The apparatus of claim 13 wherein said locator includes:

a velocity applier coupled to receive signals representative of said second vehicle velocity for applying said second vehicle velocity representative signals to each of said selected points; and

an intercept locator coupled to said coordinate determinator, said velocity applier, and to receive said first vehicle velocity representative signals for providing signals representative of said intercept locations.

15. The apparatus of claim 14 wherein said intercept locator includes:

a time calculator coupled to said velocity applier, said point selector, and to receive said first vehicle velocity representative signals for determining intercept time between said first vehicle and each selected point and providing signals representative thereof;

a multiplier coupled to said time calculator and said velocity applier for multiplying coordinates of said second vehicle velocity by said intercept time for each selected point to determine coordinate changes for each selected point due to distance traversed over said intercept time and provide signals representative thereof; and

an adder coupled to said multiplier and said coordinate determinator to establish an intercept location with said first vehicle for each selected point and provide signals representative thereof.

16. The apparatus of claim 15 wherein points are positioned on said miss distance circle, by said point selector, with equal spacing therebetween.

17. The apparatus of claim 15 further including a feasibility region analyzer coupled to said point selector and to receive said first and second vehicle velocities and said relative position of said second vehicle for determining feasible region boundaries on said miss distance circle and causing said point selector to select points on said miss distance circle only within said feasible region.

18. The apparatus of claim 17 wherein said point selector includes;

a feasibility angular range determinator coupled to said feasibility region analyzer for determining angular range subtended from said first vehicle by said feasibility region;

an angle divider coupled to said feasibility angular range determinator for dividing said angular range into equal angle segments; and

an angle edge projector coupled to said angle divider for projecting edges of said angle segments to crossing points with said miss distance circle, said crossing points chosen as said selected points.

19. The apparatus of claim 18 wherein said point selector includes means for selecting points on said miss distance circle that are equally spaced.

20. The apparatus of claim 12 wherein said projector includes:

a relative velocity determinator coupled to receive said signals representative of said first and second vehicle velocities for determining relative velocity of said second vehicle to said first vehicle;

a relative velocity analyzer coupled to receive said signals representative of said relative velocity for determining boundaries of feasibility region within said miss distance circle and providing signals representative of said boundaries; and

a point selector coupled to said relative velocity analyzer for selecting points on said miss distance circle within said feasible region and providing signals representative of said selected points.