ROBOTIC CART PULLING VEHICLE

• US 20090030569A1
• Filed: 10/02/2008
• Published: 01/29/2009
• Est. Priority Date: 08/30/2002
• Status: Active Grant

• Current Assignee: St Engineering Aethon Incorporated
• Original Assignee: Aethon
• Inventors: THORNE, Henry F.
• Granted Patent: US 8,041,455 B2
• Time in Patent Office: Days
• US Class Current: 701/25
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• 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 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

A robotic cart pulling vehicle includes a positioning error reducing system for reducing accumulated error in the ded-reckoning navigational system. The positioning error reducing system including at least one of a low load transfer point of the cart attaching mechanism, a floor variation compliance structure whereby the drive wheels maintain a substantially even distribution of load over minor surface variations, a minimal wheel contact surface structure, a calibration structure using at least one proximity sensor mounted on the robot body, and a common electrical and mechanical connection between the cart and the robot vehicle formed by a cart attaching post.

Claims

1. A robotic cart pulling vehicle, comprising:

a body;

a first drive wheel connected to the body;

a second drive wheel connected to the body, wherein a center of the first drive wheel and a center of the second drive wheel define an axis therebetween; and

a cart attachment mechanism defined at least in part by the body, wherein;

the cart attachment mechanism is centered between the first and second drive wheels; and

at least a portion of the cart attachment mechanism is below the axis.

2. The robotic cart pulling vehicle of claim 1, wherein at least one of the first and second drive wheels comprises:

a hardened annular disk; and

a coating formed over the hardened annular disk.

3. The robotic cart pulling vehicle of claim 2, wherein the coating comprises a urethane.

4. The robotic cart pulling vehicle of claim 1, wherein a width of a contact patch of the first drive wheel is less than 1.5% of a distance from the first drive wheel to the second drive wheel.

5. The robotic cart pulling vehicle of claim 1, wherein a width of a contact patch of the first drive wheel is less than 1% of a distance from the first drive wheel to the second drive wheel.

6. The robotic cart pulling vehicle of claim 1, wherein the cart attachment mechanism is configured for receiving a cart attaching post.

7. The robotic cart pulling vehicle of claim 1, wherein the cart attachment mechanism comprises a bushing.

8. The robotic cart pulling vehicle of claim 1, further comprising a housing connected to the body.

9. The robotic cart pulling vehicle of claim 8, wherein the cart attachment mechanism is defined at least in part by the housing.

10. The robotic cart pulling vehicle of claim 8, further comprising a sensor positioned within the housing.

11. The robotic cart pulling vehicle of claim 10, wherein the sensor is an infrared sensor.

12. A system, comprising:

a robotic cart pulling vehicle, wherein the robotic cart pulling vehicle comprises;

a body;

a first drive wheel connected to the body;

a second drive wheel connected to the body, wherein a center of the first drive wheel and a center of the second drive wheel define an axis therebetween; and

a cart attachment mechanism defined at least in part by the body, wherein;

the cart attachment mechanism is centered between the first and second drive wheels; and

at least a portion of the cart attachment mechanism is below the axis; and

a cart attaching post positioned within the cart attachment mechanism.

13. The system of claim 12, wherein the robotic cart pulling vehicle is rotatably connected to the cart attaching post.

14. The system of claim 12, wherein at least one of the first and second drive wheels is movable relative to the cart attaching post such that the axis is not perpendicular to the cart attaching post.

15. The system of claim 12, wherein the cart attaching post forms the following between a cart and the robotic cart pulling vehicle:

a mechanical connection; and

an electrical connection.

16. The system of claim 12, wherein the cart attaching post comprises:

a tube;

at least one conductive ring which surrounds the tube; and

a contact electrically connected to at least one of the following;

the tube; and

the at least one conductive ring.

17. A method for navigating with a robotic cart pulling vehicle, the robotic cart pulling vehicle storing a map representative of a space to be navigated, the map having virtual checkpoints associated with a wall of the space, the method comprising:

measuring a distance from the robotic cart pulling vehicle to the wall, wherein the measuring occurs while the robotic cart pulling vehicle is navigating along the wall;

forwarding a signal representative of the measured distance to a controller of the robotic cart pulling vehicle;

calculating a distance from the robotic cart pulling vehicle to the one of the walls based on the forwarded signal;

determining an orientation of the wall relative to the robotic cart pulling vehicle;

comparing the determined orientation to an expected orientation; and

adjusting a position and orientation of the robotic cart pulling vehicle within the map when the determined orientation is different from the expected orientation.

18. The method of claim 17, wherein measuring the distance comprises measuring with an infrared sensor.

19. The method of claim 17, wherein determining the orientation of the wall comprises determining the orientation based on a plurality of measured distances from the robotic cart pulling vehicle to the wall.

20. The method of claim 17, wherein comparing the determined orientation to the expected orientation comprises comparing the determined orientation to the orientation of the wall within the map.

21. The method of claim 17, further comprising determining an offset to the wall based on at least one of the following:

a sensed beginning of the wall; and

a sensed ending of the wall.