Patent ID: 8700502

Claim:
A system for fulfilling inventory requests, comprising: a plurality of inventory holders operable to store inventory items; an order holder operable to store orders, wherein each order comprises one or more inventory items and is associated with a particular inventory request; a plurality of mobile drive units operable to move the inventory holders and order holder within a workspace; a management module operable to: receive an inventory request requesting an inventory item; instruct any one of the plurality of mobile drive units to move an inventory holder storing the requested inventory item to a first location; instruct any one of the plurality of mobile drive units to move the order holder to the first location, wherein the requested inventory item is transferred from the inventory holder to the order holder at the first location; instruct any one of the plurality of mobile drive units to move the order holder to a storage space within the workspace; detect a triggering event; and in response to detecting a triggering event, transmit a priority message to any one of the plurality of mobile drive units instructing it to adjust a priority level of a task assignment, wherein the mobile drive unit which received the transmitted priority message, in response to receiving the priority message, retrieves the order holder from the storage space.