System and method for managing mobile drive units

• US 8,265,873 B2
• Filed: 10/26/2011
• Issued: 09/11/2012
• Est. Priority Date: 06/19/2006
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Kiva Systems, Inc (Amazon.com, Inc.)
• Inventors: D'Andrea, Raffaello, Wurman, Peter R., Barbehenn, Michael T., Hoffman, Andrew E., Mountz, Michael C.
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US13/281,611
• Publication Number:
  US 20120041677A1
• Time in Patent Office: 321 Days
• Field of Search: 701/400, 701/410, 701/412, 701/414, 701/500, 701/527, 340/995.19
• US Class Current: 701/527
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means

Abstract

A method for moving a mobile drive unit within a workspace includes receiving a path. The path includes at least an initial segment and one or more additional segments. The initial segment includes a portion of the path adjacent to the first point; and at least one of the additional segments includes a portion of the path adjacent to the second point. The method further includes storing the path, reserving the initial segment of the path, and moving away from the first point along the initial segment. After initiating movement along the initial segment, the method includes reserving each of the additional segments of the path and moving toward the second point along each of the additional segments while that segment is reserved.

Claims

1. A mobile drive unit for moving inventory items, comprising:

a processor operable to;

generate a first path between a first point and a second point, wherein the first path comprises a plurality of segments;

determine an initial segment of the first path;

reserve the initial segment of the first path; and

a drive module coupled to the processor and operable to move the mobile drive unit away from the first point along the initial segment of the first path;

after movement is initiated along the initial segment of the first path, the processor is further operable to determine whether to generate a new path for the mobile drive unit;

if it is determined not to generate a new path, the processor is further operable to determine a second segment of the first path; and

if it is determined to generate a new path, the processor is further operable to;

generate a second path between a current location and the second point; and

determine a first segment of the second path.

2. The mobile drive unit of claim 1, further comprising a memory operable to store the first path.

3. The mobile drive unit of claim 2, wherein if it is determined to generate a new path, the processor is further operable to generate the second path based on an algorithm that uses the stored first path as an input.

4. The mobile drive unit of claim 1, wherein the processor is further operable to:

determine at least a remainder of the first path; and

if it is determined to generate a new path, generate a second path based on an algorithm that uses at least the remainder of the first path as an input.

5. The mobile drive unit of claim 1, wherein the processor is further operable to:

detect a change in a state of an inventory system associated with the mobile drive unit; and

determine whether to generate a new path for the mobile drive unit based on the detected change.

6. The mobile drive unit of claim 5, wherein the processor is operable to detect a change in the state of the inventory system by detecting a change in a traffic level associated with the inventory system.

7. The mobile drive unit of claim 5, wherein the processor is operable to detect a change in the state of the inventory system by receiving information indicating a location of an obstacle in a workspace associated with the inventory system.

8. A method for moving inventory items, comprising:

generating a first path between a first point and a second point, wherein the first path comprises a plurality of segments;

determining an initial segment of the first path;

reserving the initial segment of the first path; and

moving a mobile drive unit away from the first point along the initial segment of the first path;

after movement is initiated along the initial segment of the first path, determining whether to generate a new path for the mobile drive unit;

if it is determined not to generate a new path, determining a second segment of the first path; and

if it is determined to generate a new path;

generating a second path between a current location and the second point; and

determining a first segment of the second path.

9. The method of claim 8, further comprising storing the first path.

10. The method of claim 9, wherein generating the second path comprises generating the second path based on an algorithm that uses the stored first path as an input.

11. The method of claim 8, further comprising determining at least a remainder of the first path, wherein generating the second path comprises generating the second path based on an algorithm that uses at least the remainder of the first path as an input.

12. The method of claim 8, further comprising:

detecting a change in a state of an inventory system associated with the mobile drive unit; and

determining whether to generate a new path for the mobile drive unit based on the detected change.

13. The method of claim 12, wherein detecting a change in the state of the inventory system comprises detecting a change in a traffic level associated with the inventory system.

14. The method of claim 12, wherein detecting a change in the state of the inventory system comprises receiving information indicating a location of an obstacle in a workspace associated with the inventory system.

15. A mobile drive unit for moving inventory items, comprising:

a processor operable to generate a path between a first point and a second point, wherein;

the path comprises an initial segment and one or more additional segments;

the initial segment includes a portion of the path adjacent to the first point; and

at least one of the additional segments includes a portion of the path adjacent to the second point;

a memory coupled to the processor and operable to store the path; and

the processor is further operable to;

determine whether to generate an additional segment of the path;

if it is determined to generate the additional segment, generate the additional segment of the path.

16. The mobile drive unit of claim 15, wherein the processor is further operable to reserve the additional segment while traversing the path.

17. The mobile drive unit of claim 15, wherein the additional segment comprises a second segment, and the processor is further operable to reserve the second segment while moving along the initial segment.

18. The mobile drive unit of claim 15, wherein the first point comprises a current location of an inventory pod and the second point comprises a destination for the inventory pod, further comprising:

a docking head coupled to the processor and operable to dock with the inventory pod; and

a drive module coupled to the processor and operable to move the inventory pod along the first segment after the docking head docks with the inventory pod.

19. The mobile drive unit of claim 15, further comprising:

a drive module coupled to the processor and operable to;

move the mobile drive unit along a final segment of the one or more additional segments;

moving an inventory pod along the final segment to the second point; and

a docking head coupled to the processor and operable to undock from the inventory pod substantially near to the second point; and

the drive module is further operable to move the mobile drive unit away from the inventory pod.

20. The mobile drive unit of claim 15, wherein the processor is further operable to release the reservation of the initial segment after moving across the initial segment.

21. The mobile drive unit of claim 15, wherein the mobile drive unit is further operable to release a portion of the initial segment after moving across the portion, wherein the portion is less than an entirety of the initial segment.