Waypoint splining for autonomous vehicle following

• US 8,510,029 B2
• Filed: 10/07/2011
• Issued: 08/13/2013
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: Southwest Research Institute
• Original Assignee: Southwest Research Institute
• Inventors: Curtis, Joshua J., McWilliams, George T., Kozak, Kristopher C.
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): GOLDMAN, RICHARD A
• Application Number:
  US13/269,039
• Publication Number:
  US 20130090802A1
• Time in Patent Office: 676 Days
• Field of Search: None
• US Class Current: 701/301
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS
• CPC Class Codes: G05D 1/0295 by at least one leading vehicle of the fleet

Abstract

A method for defining a following path for a following vehicle to autonomously follow a leader, the method including acquiring waypoints associated with a path that the leader traverses; filtering the acquired waypoints, wherein the filtering removes waypoints located outside an area of interest; generating intermediate waypoints by interpolating between adjacent pairs of the filtered waypoints if the adjacent pairs of the filtered waypoints are separated by a distance that exceeds a threshold distance; and defining a following path through the filtered waypoints and the intermediate waypoints using a least-squares spline fit to calculate the following path.

Claims

1. A method for defining a following path for a following vehicle to autonomously follow a leader, comprising:

acquiring waypoints, said waypoints associated with a path that said leader traverses;

filtering said acquired waypoints, wherein said filtering comprises identifying a preceding waypoint and a subsequent waypoint and removing waypoints that exceed a threshold number of degrees outside of a course heading defined by said preceding waypoint and subsequent waypoint, wherein said threshold number of degrees is in the range of one to ten degrees and is selected based on a speed of said leader and a waypoint acquisition sampling rate;

generating intermediate waypoints by interpolating between adjacent pairs of said filtered waypoints if said adjacent pairs of said filtered waypoints are separated by a distance that exceeds a threshold distance;

removing a previously acquired waypoint as a new waypoint is acquired, if said removal generates a course change exceeding five degrees; and

defining a following path through said filtered waypoints and said intermediate waypoints using a least-squares spline fit to calculate said following path,

wherein said following vehicle traverses said following path.

2. The method of claim 1, wherein said acquiring waypoints further comprises receiving said waypoints from said leader over a wireless communication link, said waypoints generated by a global positioning sensor (GPS) located with said leader.

3. The method of claim 1, wherein said acquiring waypoints further comprises:

determining a position for said following vehicle using a GPS located with said following vehicle;

determining an offset distance and a direction from said following vehicle to said leader using a laser incident distance and ranging (LiDAR) sensor; and

translating said position for said following vehicle by said offset distance in said direction, wherein said translating generates a waypoint.

4. The method of claim 1, further comprising removing previously acquired waypoints as new waypoints are acquired such that said spline fitting is based on a desired number of waypoints.

5. The method of claim 1, further comprising determining a remaining path length along said following path between a current position of said following vehicle and a current position of said leader, such that a desired speed and following distance are maintained.

6. The method of claim 1, further comprising identifying said leader.

7. The method of claim 1, wherein said leader is one of a vehicle or a pedestrian.

8. The method of claim 1, wherein said threshold distance is one to 500 feet.

9. A following vehicle configured to autonomously follow a leader, said following vehicle comprising:

an acquisition module configured to acquire waypoints associated with a path that said leader traverses;

a filtering module configured to filter said acquired waypoints, wherein said filtering comprises identifying a preceding waypoint and a subsequent waypoint and removing waypoints that exceed a threshold number of degrees outside of a course heading defined by said preceding waypoint and subsequent waypoint, wherein said threshold number of degrees is in the range of one to ten degrees and is selected based on a speed of said leader and a waypoint acquisition sampling rate;

an interpolating module configured to generate intermediate waypoints by interpolating between adjacent pairs of said filtered waypoints if said adjacent pairs of said filtered waypoints are separated by a distance that exceeds a threshold distance;

said acquisition module further configured to remove a previously acquired waypoint as a new waypoint is acquired, if said removal generates a course change exceeding five degrees; and

a curve fitting module configured to define a following path through said filtered waypoints and said intermediate waypoints using a least-squares spline fit to calculate said following path.

10. The following vehicle of claim 9, further comprising a wireless communication link configured to receive said waypoints from said leader, said waypoints generated by a GPS located with said leader.

11. The following vehicle of claim 9, further comprising:

a GPS configured to determine a position for said following vehicle;

a LiDAR configured to determine an offset distance and a direction from said following vehicle to said leader; and

a translating module configured to translate said position for said following vehicle by said offset distance in said direction, wherein said translating generates a waypoint.

12. The following vehicle of claim 9, wherein said acquisition module further removes previously acquired waypoints as new waypoints are acquired such that said curve fitting is based on a desired number of waypoints.

13. The following vehicle of claim 9, further comprising a speed control module configured to determine a remaining path length along said following path between a current position of said following vehicle and a current position of said leader, and maintain a desired speed and following distance to said leader based on said remaining path length.

14. The following vehicle of claim 9, further comprising an identification module configured to identify said leader.

15. The following vehicle of claim 9, wherein said threshold distance is one to 500 feet.

16. An article comprising a non-transitory storage medium having stored thereon instruction that when executed by a machine result in the following operations for defining a following path for a following vehicle to autonomously follow a leader:

acquiring waypoints, said waypoints associated with a path that a leader traverses;

filtering said acquired waypoints, wherein said filtering comprises identifying a preceding waypoint and a subsequent waypoint and removing waypoints that exceed a threshold number of degrees outside of a course heading defined by said preceding waypoint and subsequent waypoint, wherein said threshold number of degrees is in the range of one to ten degrees and is selected based on a speed of said leader and a waypoint acquisition sampling rate;

generating intermediate waypoints by interpolating between adjacent pairs of said filtered waypoints if said adjacent pairs of said filtered waypoints are separated by a distance that exceeds a threshold distance;

removing a previously acquired waypoint as a new waypoint is acquired, if said removal generates a course change exceeding five degrees; and

defining a following path through said filtered waypoints and said intermediate waypoints using a least-squares spline fit to calculate said following path.

17. The article of claim 16 wherein said acquiring waypoints further comprises receiving said waypoints from said leader over a wireless communication link, said waypoints generated by a GPS located with said leader.

18. The article of claim 16 wherein said acquiring waypoints further comprises:

determining a position for said following vehicle using a GPS located with said following vehicle;

determining an offset distance and a direction from said following vehicle to said leader using a LiDAR sensor; and

translating said position for said following vehicle by said offset distance in said direction, wherein said translating generates a waypoint.

19. The article of claim 16, further comprising determining a remaining path length along said following path between a current position of said following vehicle and a current position of said leader, such that a desired speed and following distance are maintained.

20. The article of claim 16, wherein said threshold distance is one to 500 feet.