Method and system for transporting inventory items

• US 8,170,711 B2
• Filed: 01/28/2011
• Issued: 05/01/2012
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Kiva Systems, Inc (Amazon.com, Inc.)
• Inventors: D'Andrea, Raffaello, Mansfield, Peter K., Mountz, Michael C., Polic, Dennis, Dingle, Patrick R.
• Primary Examiner(s): Crawford, Gene
• Assistant Examiner(s): CUMBESS, YOLANDA RENEE
• Application Number:
  US13/016,046
• Publication Number:
  US 20110125312A1
• Time in Patent Office: 459 Days
• Field of Search: None
• US Class Current: 700/214
• CPC Class Codes: B66F 9/063 Automatically guided
• CPC Class Codes: G05B 13/00 Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion G05B19/00 takes precedence
• CPC Class Codes: G05D 1/021 specially adapted to land vehicles
• CPC Class Codes: G05D 1/0234 using optical markers or beacons optical beacons per se G01S1/70

Abstract

A system for transporting inventory items includes an inventory holder capable of storing inventory items and a mobile drive unit. The mobile drive unit is capable of moving to a first point with the inventory holder at least one of coupled to and supported by the mobile drive unit. The mobile drive unit is additionally capable of determining a location of the inventory holder and calculating a difference between the location of the inventory holder and the first point. The mobile drive unit is then capable of determining whether the difference is greater than a predetermined tolerance. In response to determining that the difference is greater than the predetermined tolerance, the mobile drive unit is also capable of moving to a second point based on the location of the inventory holder, docking with the inventory holder, and moving the mobile drive unit and the inventory holder to the first point.

Claims

1. A method for transporting inventory items, comprising:

moving a mobile drive unit to a first point while the mobile drive unit is docked with an inventory holder;

determining a location of the inventory holder while the mobile drive unit is docked with the inventory holder;

calculating a difference between the location of the inventory holder and the first point;

determining whether the difference is greater than a predetermined tolerance;

in response to determining that the difference is less than the predetermined tolerance, undocking from the inventory holder; and

in response to determining that the difference is greater than the predetermined tolerance;

moving the mobile drive unit to a second point based on the location of the inventory holder; and

undocking the mobile drive unit with the inventory holder.

2. The method of claim 1, wherein the moving the mobile drive unit to a second point comprises:

determining an adjusted location based, at least in part, on the location of the inventory holder; and

moving the inventory holder to the adjusted location.

3. The method of claim 1, wherein determining the location of the inventory holder while the mobile drive unit is docked with the inventory holder comprises determining a location of the mobile drive unit and determining a position of at least part of the inventory holder relative to the location of the mobile drive unit.

4. The method of claim 3, wherein determining the location of the mobile drive unit comprises:

detecting a fixed object; and

determining the location of the mobile drive unit based on the fixed object.

5. The method of claim 1, wherein determining the location of the inventory holder while the mobile drive unit is docked with the inventory holder comprises:

detecting a holder identifier associated with the inventory holder; and

determining the location of the inventory holder based on a position of the holder identifier relative to a location of the mobile drive unit.

6. The method of claim 1, further comprising determining that the mobile drive unit has reached the first point based on detecting a fixed object associated with the first point.

7. An apparatus comprising:

a drive module operable to propel the apparatus towards a destination;

a docking actuator operable to facilitate docking with an inventory holder;

a control module operable to;

cause the apparatus to move to a first point while the apparatus is docked with an inventory holder;

determine a location of the inventory holder while the apparatus is docked with the inventory holder;

calculate a difference between the location of the inventory holder and the first point;

determine whether the difference is greater than a predetermined tolerance;

in response to determining that the difference is less than the predetermined tolerance, cause the apparatus to undock from the inventory holder; and

in response to determining that the difference is greater than the predetermined tolerance;

cause the apparatus to move to a second point based on the location of the inventory holder; and

cause the apparatus to undock with the inventory holder.

8. The apparatus of claim 7, wherein the control module is operable to cause the apparatus to move to the second point by:

determining an adjusted location based, at least in part, on the location of the inventory holder; and

causing the apparatus to move the inventory holder to the adjusted location.

9. The apparatus of claim 7, wherein the control module is operable to determine the location of the inventory holder while the apparatus is docked with the inventory holder by:

determining a location of the apparatus; and

determining a position of at least part of the inventory holder relative to the location of the apparatus.

10. The apparatus of claim 9, wherein the control module is operable to determine the location of the apparatus by:

detecting a fixed object; and

determining the location of the apparatus based on the fixed object.

11. The apparatus of claim 7, wherein the control module is operable to determine the location of the inventory holder while the apparatus is docked with the inventory holder by:

detecting a holder identifier associated with the inventory holder; and

determining the location of the inventory holder based on a position of the holder identifier relative to a location of the apparatus.

12. The apparatus of claim 7, the control module further operable to determine that the apparatus has reached the first point based on detecting a fixed object associated with the first point.

13. The apparatus of claim 7, further comprising means for determining a location of the apparatus.

14. A system for storing inventory items, comprising:

an inventory holder operable to store inventory items; and

a mobile drive unit operable to;

move to a first point while docked with an inventory holder;

determine a location of the inventory holder while docked with the inventory holder;

calculate a difference between the location of the inventory holder and the first point;

determine whether the difference is greater than a predetermined tolerance;

in response to determining that the difference is less than the predetermined tolerance, undock from the inventory holder; and

in response to determining that the difference is greater than the predetermined tolerance;

move to a second point based on the location of the inventory holder; and

undock with the inventory holder.

15. The system of claim 14, wherein the mobile drive unit is operable to move to the second point by:

determining an adjusted location based, at least in part, on the location of the inventory holder; and

moving the inventory holder to the adjusted location.

16. The system of claim 14, wherein the mobile drive unit is operable to determine the location of the inventory holder while docked with the inventory holder by:

determining a location of the mobile drive unit; and

determining a position of at least part of the inventory holder relative to the location of the mobile drive unit.

17. The system of claim 16, wherein the mobile drive unit is operable to determine the location of the mobile drive unit by:

detecting a fixed object; and

determining the location of the mobile drive unit based on the fixed object.

18. The system of claim 14, wherein the mobile drive unit is operable to determine the location of the inventory holder while docked with the inventory holder by:

detecting a holder identifier associated with the inventory holder; and

determining the location of the inventory holder based on a position of the holder identifier relative to a location of the mobile drive unit.

19. The system of claim 14, the mobile drive unit further operable to determine that the mobile drive unit has reached the first point based on detecting a fixed object associated with the first point.

20. The system of claim 14, further comprising means for determining the location of the mobile drive unit.