SYSTEM AND METHOD FOR MANEUVERING A MOBILE DRIVE UNIT

• US 20070290040A1
• Filed: 06/19/2006
• Published: 12/20/2007
• Est. Priority Date: 06/19/2006
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Wurman, Peter R., D'Andrea, Raffaello, Barbehenn, Michael T., Hoffman, Andrew E., Mountz, Michael C., Koehler, David C.
• Granted Patent: US 8,649,899 B2
• Time in Patent Office: Days
• US Class Current: 235/385
• CPC Class Codes: B65G 1/137 with arrangements or automatic control means for selecting which articles are to be removed
• CPC Class Codes: G05D 1/0289 with means for avoiding collisions between vehicles vehicle fittings for automatically controlling speed including means for detecting potential obstacles B60K31/0008; avoiding obstacles by action on the steering system B62D; radar, sonar, lidar systems designed for anti-collision purposes G01S13/93, G01S15/93, G01S17/93
• CPC Class Codes: G05D 2201/0216 Vehicle for transporting goods in a warehouse, factory or similar
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders

Abstract

A method of rotating an inventory holder includes moving an inventory holder towards a rotation area along a straight segment of a path with a first face of the inventory holder facing a first direction. The rotation area includes a portion of a workspace designated for rotation of inventory holders. The method further includes moving the inventory holder into the rotation area along a first arced segment with an orientation of the first face perpendicular to the first arced segment. The method additionally includes executing a rotation maneuver within the rotation area and moving the inventory holder out of the rotation area along a second arced segment with a second face facing the first direction.

Claims

1. A method of rotating an inventory holder, comprising:

moving an inventory holder towards a rotation area along a straight segment of a path with a first face of the inventory holder facing a first direction, wherein the rotation area comprises a portion of a workspace designated for rotation of inventory holders;

moving the inventory holder into the rotation area along a first arced segment with an orientation of the first face perpendicular to the first arced segment;

executing a rotation maneuver within the rotation area; and

moving the inventory holder out of the rotation area along a second arced segment with a second face facing the first direction.

2. The method of claim 1, further comprising selecting a rotation maneuver from a group comprising a ninety-degree rotation, a one-hundred-and-eighty-degree rotation, and a two-hundred-and-seventy-degree rotation, and wherein executing a rotation maneuver comprises executing the selected rotation maneuver.

3. The method of claim 1, wherein executing a rotation maneuver comprises:

receiving information identifying a face to be presented;

selecting a rotation maneuver based on the received information; and

executing the selected rotation maneuver within the rotation area.

4. The method of claim 3, further comprising, after executing the rotation maneuver, presenting a particular face of the inventory holder to an inventory station where inventory items are processed,

5. The method of claim 1, wherein executing a rotation maneuver comprises:

executing a rotation maneuver in which the mobile drive unit rotates without the inventory holder rotating; and

executing a rotation maneuver in which both the mobile drive unit and the inventory holder rotate.

6. The method of claim 1, further comprising:

moving a mobile drive unit to the inventory holder; and

docking the mobile drive unit with the inventory holder, and wherein moving the inventory holder towards the rotation area along the straight segment comprises transporting the inventory holder with the mobile drive unit after the mobile drive unit docks with the inventory holder.

7. The method of claim 6, wherein docking the mobile drive unit with the inventory holder comprises:

docking the mobile drive unit with the inventory holder;

moving the mobile drive unit and the inventory holder in a first preliminary direction;

rotating the mobile drive unit without rotating the inventory holder; and

moving the mobile drive unit and the inventory holder in a second preliminary direction.

8. The method of claim 1, further comprising:

transmitting a reservation request from the mobile drive unit to a management module identifying a portion of the workspace;

receiving, at the management module, the reservation request; and

in response to receiving the reservation request at the management module, designating the identified portion of the workspace as a rotation area.

9. The method of claim 8, wherein:

the workspace comprises a grid-based workspace that includes a plurality of cells; and

transmitting the reservation request comprises transmitting a reservation request from the mobile drive unit to the management module identifying a plurality of cells in the workspace.

10. The method of claim 8, further comprising determining based on a location of the mobile drive unit to terminate the designation of the identified portion as a rotation area.

11. The method of claim 8, further comprising reserving the identified portion of the workspace for the mobile drive unit, in response to receiving the reservation request at the management module.

12. The method of claim 11, further comprising deciding, based on a location of the mobile drive unit, to terminate a reservation of the identified portion of the workspace.

13. A system for transporting inventory items, comprising:

a plurality of inventory holders operable to store inventory items;

a workspace comprising a plurality of workspace cells and one or more rotation areas;

a plurality of mobile drive units, each mobile drive unit operable to transport an inventory holder without rotating the inventory holder while moving through one or more workspace cells and to selectively rotate the inventory holder while moving through one of the rotation areas.

14. The system of claim 13, wherein each mobile drive unit is operable to selectively rotate the inventory holder by at least one of:

executing a rotation maneuver in which the mobile drive unit rotates without the inventory holder rotating; and

executing a rotation maneuver in which both the mobile drive unit and the inventory holder rotate.

15. The system of claim 14, further comprising a management module operable to transmit a task assignment to one of the mobile drive units, the task assignment identifying a location associated with an inventory holder, and wherein each mobile drive unit is further operable to:

receive the task assignment from the management module;

move to the location identified by the task assignment; and

dock with an inventory holder at the identified location.

16. The system of claim 15, wherein the mobile drive units are each operable to transport an inventory holder without rotating the inventory holder while moving through one or more workspace cells by:

docking with the inventory holder;

moving the inventory holder in a first direction;

rotating the mobile drive unit without rotating the inventory holder; and

moving the inventory holder in a second direction.

17. The system of claim 13, wherein each mobile drive unit is further operable to receive information identifying a face to be presented and wherein each mobile drive unit is operable to selectively rotate the inventory holder by:

selecting a rotation maneuver based on the received information; and

executing the rotation maneuver while moving through one of the rotation areas.

18. The system of claim 17, further comprising one or more inventory stations where inventory items are processed, and wherein each mobile drive unit is operable to present a particular face of the inventory holder to the inventory station after executing a selected rotation maneuver.

19. The system of claim 13, wherein each mobile drive unit is operable to selectively rotate the inventory holder while moving through one of the rotation areas by:

moving the inventory holder towards the rotation area along a straight segment of a path with a first face of the inventory holder facing a first direction;

moving the inventory holder into the rotation area along a first arced segment with an orientation of the first face perpendicular to the first arced segment;

executing a selected rotation maneuver within the rotation area; and

moving the inventory holder out of the rotation area along a second arced segment with a second face facing the first direction.

20. The system of claim 13, wherein each mobile drive unit is operable to execute the selected rotation maneuver within the rotation area by:

selecting a rotation maneuver from a group comprising a ninety-degree rotation, a one-hundred-and-eighty-degree rotation, and a two-hundred-and-seventy-degree rotation; and

executing the selected rotation maneuver.

21. The system of claim 13, wherein at least one mobile drive unit is further operable to transmit a reservation request from that mobile drive unit to a management module identifying a portion of the workspace, and further comprising the management module operable to:

receive the reservation request; and

in response to receiving the reservation request, designate the identified portion of the workspace as a rotation area.

22. The system of claim 21, wherein the workspace comprises a grid-based workspace that includes a plurality of cells, and wherein the transmitting mobile drive unit is operable to transmit the reservation request by transmitting a reservation request from the transmitting mobile drive unit to the management module identifying a plurality of cells in the workspace.

23. The system of claim 21, wherein the management module is further operable to determine based on a location of the transmitting mobile drive unit to terminate the designation of the identified portion as a rotation area.

24. The system of claim 21, wherein the management module is further operable to reserve the identified portion of the workspace for the transmitting mobile drive unit, in response to receiving the reservation request at the management module.

25. The system of claim 24, wherein the management module is further operable to decide, based on a location of the transmitting mobile drive unit, to terminate a reservation of the identified portion of the workspace.

26. A mobile drive unit for transporting an inventory holder, operable to:

move an inventory holder towards a rotation area along a straight segment of a path with a first face of the inventory holder facing a first direction, wherein the rotation area comprises a portion of a workspace designated for rotation of inventory holders;

move the inventory holder into the rotation area along a first arced segment with an orientation of the first face perpendicular to the first arced segment;

execute a rotation maneuver within the rotation area; and

move the inventory holder out of the rotation area along a second arced segment with a second face facing the first direction.

27. A system for transporting inventory items, comprising:

means for moving an inventory holder towards a rotation area along a straight segment of a path with a first face of the inventory holder facing a first direction, wherein the rotation area comprises a portion of a workspace designated for rotation of inventory holders;

means for moving the inventory holder into the rotation area along a first arced segment with an orientation of the first face perpendicular to the first arced segment;

means for executing a rotation maneuver within the rotation area; and

means for moving the inventory holder out of the rotation area along a second arced segment with a second face facing the first direction.

28. A method for moving inventory items, comprising:

docking a mobile drive unit to an inventory holder;

moving the mobile drive unit and the inventory holder in a first direction;

while the mobile drive unit is docked with the inventory holder, rotating the mobile drive unit without rotating the inventory holder; and

moving the mobile drive unit and the inventory holder in a second direction.

29. The method of claim 28, wherein rotating the mobile drive unit without rotating the inventory holder comprises:

disengaging a rotation lock, wherein the rotation lock prevents the mobile drive unit from rotating independently from the inventory holder when engaged;

after disengaging the rotation lock, rotating the mobile drive without rotating the inventory holder.

30. The method of claim 29, further comprising:

engaging the rotation lock; and

after engaging the rotation lock, rotating the inventory holder by rotating the mobile drive unit.

31. The method of claim 28, wherein docking the mobile drive unit with the inventory holder comprises:

moving the mobile drive unit to a location of the inventory holder; and

docking the mobile drive unit with the inventory holder at the location of the inventory holder, and further comprising;

moving the mobile drive unit and the inventory holder to a destination;

undocking the mobile drive unit from the inventory holder at the destination; and

moving the mobile drive unit away from the inventory holder.

32. The method of claim 31, wherein docking the mobile drive unit with the inventory holder comprises:

positioning the mobile drive unit beneath the inventory holder; and

raising a docking head of the mobile drive unit towards the inventory holder.

33. A mobile drive unit for moving inventory items, the mobile drive unit operable to:

dock with an inventory holder;

move the inventory holder in a first direction;

while docked with the inventory holder, rotate the mobile drive unit without rotating the inventory holder; and

move the inventory holder in a second direction.

34. The mobile drive unit of claim 33, wherein the mobile drive unit comprises a rotation lock operable to prevent the mobile drive unit from rotating independently from the inventory holder when engaged, and the mobile drive unit is operable to rotate the mobile drive unit without rotating the inventory holder by:

disengaging the rotation lock; and

after disengaging the rotation lock, rotating the mobile drive without rotating the inventory holder.

35. The mobile drive unit of claim 34, further operable to:

engage the rotation lock; and

after engaging the rotation lock, rotate the inventory holder by rotating the mobile drive unit.

36. The mobile drive unit of claim 33, wherein the mobile drive unit is operable to dock with the inventory holder by:

moving the mobile drive unit to a location of the inventory holder; and

docking with the inventory holder at the location of the inventory holder, and the mobile drive unit is further operable to;

move the inventory holder to a destination;

undock from the inventory holder at the destination; and

move away from the inventory holder.

37. The mobile drive unit of claim 36, wherein the mobile drive unit further comprises a docking head operable to couple to the inventory holder, and wherein the mobile drive unit is operable to dock with the inventory holder by:

positioning the docking head beneath the inventory holder; and

raising the docking head towards the inventory holder.