FOLLOWER VEHICLE CONTROL SYSTEM AND METHOD FOR FORWARD AND REVERSE CONVOY MOVEMENT

• US 20100049374A1
• Filed: 09/26/2008
• Published: 02/25/2010
• Est. Priority Date: 08/20/2008
• Status: Active Grant

• Current Assignee: Autonomous Solutions, Inc.
• Original Assignee: Autonomous Solutions, Inc.
• Inventors: Ferrin, Jeffrey L., Thayn, Brett, Hornberger, Michael
• Granted Patent: US 8,116,921 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• 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 vehicle control system for causing a follower vehicle to follow a leader may have a tether system mounted to the follower vehicle. The tether system may include a tether having an end adopted to be attached to the leader, a length sensor, and an angle sensor. A path tracking system operatively associated with the tether system determines a path traveled by the leader. A path control system operatively associated with the path tracking system and the follower vehicle causes the follower vehicle to follow the path traveled by the leader. A spacing control system operatively associated with the path tracking system and the follower vehicle causes the follower vehicle to maintain a predetermined spacing between the follower vehicle and the leader.

Claims

1. A vehicle control system for causing a follower vehicle to follow a leader, comprising:

a tether system mounted to the follower vehicle, said tether system comprising;

a tether having an end adopted to be attached to the leader;

a length sensor operatively associated with said tether, said length sensor sensing a length of said tether extending between the follower vehicle and the leader; and

an angle sensor operatively associated with said tether, said angle sensor sensing an angle between said tether and the follower vehicle;

a path tracking system operatively associated with said tether system, said path tracking system determining a path traveled by the leader;

a path control system operatively associated with said path tracking system and the follower vehicle, said path control system causing the follower vehicle to follow the path traveled by the leader; and

a spacing control system operatively associated with said path tracking system and the follower vehicle, said spacing control system causing the follower vehicle to maintain a predetermined spacing between the follower vehicle and the leader.

2. The system of claim 1, wherein said path control system provides a desired curvature to the follower vehicle, said desired curvature causing the follower vehicle to follow the path traveled by the leader.

3. The system of claim 1, wherein said spacing control system causes the follower vehicle to maintain a predetermined spacing between the follower vehicle and the leader, said predetermined spacing being measured along the path traveled by the leader.

4. The system of claim 3, wherein said spacing control system provides desired velocity to the follower vehicle, said desired velocity causing the follower vehicle to maintain the predetermined spacing.

5. The system of claim 1, further comprising a dead reckoning system operatively associated with the follower vehicle, said path tracking system, and said path control system, said dead reckoning system producing position and heading estimates of the follower vehicle.

6. The system of claim 5, wherein said dead reckoning system comprises an odometer and a steering angle sensor.

7. The system of claim 5, wherein said dead reckoning system comprises an odometer and a heading gyroscope.

8. The system of claim 1, further comprising a direction control system operatively associated with the follower vehicle and said tether system, said direction control system selecting between a forward travel direction and a reverse travel direction for the follower vehicle based on a change in length of said tether.

9. The system of claim 1, further comprising a damper operatively associated with said angle sensor.

10. The system of claim 1, wherein said tether system further comprises:

a spool mounted for rotation with respect to said tether system, said spool holding a length of said tether;

a motor operatively connected to said spool, said motor rotating said spool to pay-out and reel-in said tether; and

a tether guide operatively associated with said motor, said spool, and said tether.

11. A vehicle control system for causing a follower vehicle to follow a leader, comprising:

a tether mounted to the follower vehicle, said tether having an end adopted to be attached to the leader;

length sensing means operatively associated with said tether for sensing a length of said tether extending between the follower vehicle and the leader;

angle sensing means operatively associated with said tether for sensing an angle between said tether and the follower vehicle;

a path tracking system operatively associated with said length sensing means and said angle sensing means, said path tracking system determining a path traveled by the leader;

a path control system operatively associated with said path tracking system and the follower vehicle, said path control system causing the follower vehicle to follow the path traveled by the leader; and

a spacing control system operatively associated with said path tracking system and the follower vehicle, said spacing control system causing the follower vehicle to maintain a predetermined spacing between the follower vehicle and the leader.

12. The system of claim 11, further comprising a dead reckoning system operatively associated with the follower vehicle, said path tracking system, and said path control system, said dead reckoning system producing position and heading estimates of the follower vehicle.

13. The system of claim 11, further comprising tension control means operatively associated with said tether for controlling a tension in the tether.

14. The system of claim 13, wherein said tension control means varies the tension in the tether as a function of a velocity of the leader.

15. A method for causing a follower vehicle to follow a leader, comprising:

connecting the follower vehicle to the leader with a tether;

measuring a length of the tether connecting the follower vehicle to the leader;

measuring an angle between the tether and the follower vehicle;

determining a position of the leader based on the measured length and the measured angle;

determining a path traveled by the leader based on a plurality of determined leader positions;

steering the follower vehicle so that the follower vehicle substantially follows the path traveled by the leader; and

controlling a velocity of the follower vehicle so that the follower vehicle maintains a predetermined distance from the leader.

16. The method of claim 15, wherein steering the follower vehicle comprises:

determining an actual position of the follower vehicle;

comparing the actual position of the follower vehicle with a desired position of the follower vehicle to determine an off-path error;

using the off-path error to calculate a desired curvature; and

using the desired curvature to produce a steering command for the follower vehicle.

17. The method of claim 16, wherein using the off-path error to calculate a desired curvature comprises:

establishing a look-ahead length;

using the look-ahead length to identify a look-ahead point on the path traveled by the leader; and

using the look-ahead point to determine the off-path error.

18. The method of claim 17, wherein the look-ahead length is a function of the velocity of the follower vehicle.

19. The method of claim 15, wherein controlling a velocity of the follower vehicle comprises controlling a velocity of the follower vehicle so that the follower vehicle maintains a predetermined distance from the leader, the predetermined distance being measured along the path traveled by the leader.

20. The method of claim 19, wherein the predetermined distance is a function of the velocity of the leader.

21. The method of claim 15, wherein controlling the velocity of the follower vehicle comprises:

determining an actual length between the leader and the follower vehicle, the actual length being measured along the path traveled by the leader;

determining a desired length between the leader and the follower vehicle, the desired length being measured along the path traveled by the leader;

comparing the actual length and the desired length to determine a vehicle spacing error; and

using the vehicle spacing error to control the velocity of the follower vehicle.

22. The method of claim 15, further comprising:

operating the follower vehicle in a reverse travel direction; and

steering the follower vehicle in the reverse travel direction to follow in reverse at least a portion of the path traveled by the leader.

23. The method of claim 15, further comprising:

operating the follower vehicle in a reverse travel direction; and

steering the follower vehicle in the reverse travel direction based on the measured angle between the tether and the follower vehicle.

24. The method of claim 15, further comprising selecting to operate the follower vehicle in either a forward travel direction or a reverse travel direction for the follower vehicle based on a change in length of said tether.