Automatic guided vehicle control system

• US 5,925,080 A
• Filed: 03/31/1997
• Issued: 07/20/1999
• Est. Priority Date: 03/29/1996
• Status: Expired due to Fees

• Current Assignee: Mazda Motor Corporation
• Original Assignee: Mazda Motor Corporation
• Inventors: Morimoto, Hiroyuki, Moriyama, Koichi, Shimbara, Yoshimi, Teramoto, Koji
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/834,824
• Time in Patent Office: 841 Days
• Field of Search: 701/23, 701/24, 701/25, 701/26, 701/41, 180/168, 180/167, 180/169, 318/587, 318/618, 318/652, 706/900, 706/905, 706/20, 706/23, 706/21
• US Class Current: 701/23
• CPC Class Codes: G05D 1/0244 using reflecting strips
• CPC Class Codes: G05D 1/0263 using magnetic strips

Abstract

A automatic guided vehicle travels on a prearranged travel path established by a path guide and detects lateral deviation of the vehicle from a path guide to control the direction of travel of the vehicle by steering the vehicle according to a prescribed relationship between steering angle and lateral deviation which is installed in the form of ruling maps in the vehicle.

Claims

1. A vehicle control system for controlling a motor driven vehicle having right and left drive wheels arranged transversely side by side which is guided by path guide means to travel on a prearranged path established by said path guide means, said vehicle control system comprising:

steering means installed on said motor driven vehicle for steering said motor driven vehicle with a controlled steering variable to change a travel direction of said motor drive vehicle, said steering means comprising a steering disk supported for rotation by said motor driven vehicle and wheel drive means installed on said steering disk for independently driving said right and left drive wheels;

guide monitoring means installed on said motor driven vehicle for monitoring a lateral deviation of said motor driven vehicle from said path guide means; and

control means for controlling said wheel drive means by a prescribed relationship between said controlled steering variable and said lateral deviation to drive said drive wheels at different travel speeds according to said controlled steering variable such that a speed difference between said different travel speed for a specific lateral deviation becomes smaller than an increase in said travel speed of said motor driven vehicle so as thereby to control said motor driven vehicle in travel direction.

2. The vehicle control system as defined in claim 1, wherein said control means includes a memory storing a map of said prescribed relationship.

3. The vehicle control system as defined in claim 1, wherein said control means controls said steering means by a plurality of said prescribed relationships used accordingly to travel speeds of said motor driven vehicle, respectively.

4. The vehicle control system as defined in claim 3, wherein said maps include at least one which is used during acceleration of said motor driven vehicle and another one which is used during deceleration of said motor driven vehicle.

5. The vehicle control system as defined in claim 3, wherein said maps include at least one which is used during forward travel of said motor driven vehicle and another one which is used during backward travel of said motor driven vehicle.

6. The vehicle control system as defined in claim 4, wherein said map used during acceleration of said motor driven vehicle sets said controlled steering variable to a larger value in a smallest range of said lateral deviations than in other ranges of said lateral deviations, and said map used during deceleration of said motor driven vehicle sets said controlled steering variable to a smaller value in said smallest range of said lateral deviations than in said other ranges of said lateral deviations.

7. The vehicle control system as defined in claim 1, wherein said control means includes a memory storing maps of said prescribed relationship differently established.

8. The vehicle control system as defined in claim 7, and further comprising travel instruction means disposed along said path guide means for providing travel instructions relating at least to travel speeds of said motor driven vehicle, and travel instruction monitoring means installed on said motor driven vehicle for monitoring said travel instructions by which a travel speed of said motor driven vehicle is controlled, wherein said control means selects one out of said maps of said prescribed relationships according to said travel speeds.

9. A vehicle control system for controlling a motor driven vehicle having right and left drive wheels arranged transversely side by side which is guided by path guide means to travel on a prearranged path established by said path guide means, said vehicle control system comprising:

steering means installed on said motor drive vehicle for steering said motor driven vehicle with a controlled steering variable to change a travel direction of said motor drive vehicle;

guide monitoring means installed on said motor drive vehicle for monitoring a lateral deviation of said motor driven vehicle from said path guide means;

wheel drive motors for driving said right and left drive wheels, respectively;

travel speed instruction means located along said prearranged path for providing travel speed instructions for said motor driven vehicle;

instruction monitoring means installed on said motor driven vehicle for monitoring said travel speed instructions on said speed instruction means; and

control means for controlling said steering means by a prescribed relationship between said controlled steering variable and said lateral deviation to steer said motor driven vehicle so as thereby to control said motor driven vehicle in travel direction and controlling said drive motor with a control parameter to drive said drive wheels, said control means changing said control parameter so as to gradually change a traveling speed of said motor driven vehicle according to said travel speed instruction.

10. The vehicle control system as defined in claim 9, wherein said control means comprises a speed control circuit for controlling said travel speed of said motor driven vehicle, a steering control circuit for controlling said steering means to control travel of said motor driven vehicle along said path guide means, a proportional control circuit for providing said controlled variable proportional to a target vehicle travel speed, a motor drive circuit for driving said drive motor, a feedback control circuit for detecting a rotational speed of said drive motor and providing a feedback signal for said proportional control circuit, and a feedforward control circuit disposed between an output end of said steering control circuit and a point between an output end of said proportional control circuit and an input end of said motor drive circuit for compensating disturbance.

11. The vehicle control system as defined in claim 9, wherein said control means changes said control parameter based on a change rate of said proportional controlled valuable.

12. The vehicle control system as defined in claim 9, wherein said control means includes a memory storing maps of a plurality steps of travel speeds into which said instructed travel speeds are divided.

13. The vehicle control system as defined in claim 9, wherein said steering means comprises said drive motors and said control means controls said drive motor so as to drive said drive wheels at different speeds according to said controlled steering variable, thereby steering said motor driven vehicle.

14. The vehicle control system as defined in claim 13, wherein said control means has a dead zone for a specified range of lateral deviations.

15. A vehicle control system for controlling a motor driven vehicle which is guided by path guide means to travel on a prearranged path established by said path guide means, said vehicle control system comprising:

steering means installed on said vehicle for steering said single drive wheel with a controlled steering variable to change a travel direction of said motor driven vehicle, said steering means comprising a steering disk supported for rotation by said motor driven vehicle, wheel drive means installed on said steering disk for driving a single drive wheel of said motor driven vehicle and steering disk drive means secured to said motor driven vehicle for driving said steering disk;

guide monitoring means installed on said motor driven vehicle for monitoring a lateral deviation of said motor driven vehicle from said path guide means; and

control means for controlling said steering disk drive means to drive said steering disk through an angle according to a prescribed relationship between said controlled steering variable and said lateral deviation so as to steer said motor driven vehicle, thereby controlling said motor driven vehicle in travel direction, said control means including a memory storing maps of said prescribed relationships differently established and selectively using said maps according to travel speeds of said motor driven vehicle to control travel of said motor driven vehicle.

16. A vehicle control system for controlling a motor driven vehicle having a right and left drive wheels arranged transversely side by side, respectively which is guided by path guide means to travel on a prearranged path established by said path guide means, said vehicle control system comprising:

steering means installed on said motor driven vehicle for steering said motor driven vehicle with a controlled steering variable to change a travel direction of said motor drive vehicle;

guide monitoring means installed on said motor driven vehicle for monitoring a lateral deviation of said motor driven vehicle from said path guide means;

wheel drive motors for driving said right and left drive wheels;

travel speed instruction means located along said prearranged path for providing travel speed instructions for said motor driven vehicle;

instruction monitoring means installed on said motor driven vehicle for monitoring said travel speed instructions on said speed instruction means; and

control means for controlling said wheel drive motors by a prescribed relationship between said controlled steering variable and said lateral deviation to steer said motor driven vehicle so as thereby to control said motor driven vehicle in travel direction and controlling said wheel drive motors with said travel speed instruction to drive said drive wheels.

17. The vehicle control system as defined in claim 16, wherein said steering means comprises a steering disk supported for rotation by said motor driven vehicle and wheel drive means installed on said steering disk for independently driving said right and left drive wheels, and said control means controls said wheel drive means to drive said drive wheels at different speeds according to said controlled steering variable so as thereby to steer said motor drive vehicle.

18. A vehicle control system for controlling a motor driven vehicle having a single drive wheel which is guided by path guide means to travel on a prearranged path established by said path guide means, said vehicle control system comprising:

steering means installed on said motor driven vehicle for steering said motor driven vehicle with a controlled steering variable to change a travel direction of said motor drive vehicle;

guide monitoring means installed on said motor driven vehicle for monitoring a lateral deviation of said motor driven vehicle from said path guide means;

a wheel drive motor for driving said drive wheel;

travel speed instruction means located along said prearranged path for providing travel speed instructions for said motor driven vehicle;

instruction monitoring means installed on said motor driven vehicle for monitoring said travel speed instructions on said speed instruction means; and

control means for controlling said steering means by a prescribed relationship between said controlled steering variable and said lateral deviation to steer said motor driven vehicle so as thereby to control said motor driven vehicle in travel direction and controlling said drive motor with said travel speed instruction to drive said drive wheels.

19. A vehicle control system as defined in claim 18, wherein said steering means comprises a steering disk supported for rotation by said motor driven vehicle and a steering disk drive means secured to said motor driven vehicle for driving said steering disk, and said control means controls said steering disk drive means to drive said steering disk through an angle according to said controlled steering variable.

20. A vehicle control system as defined in claim 18, wherein said control means includes a memory storing maps of said prescribed relationships differently established and selectively uses said maps according to travel steeds of said motor driven vehicle to control said steering means.