Method and system for transporting inventory items
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.
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.