US Patent 9008830 Inventory system with connectable inventory holders

A system includes a station and a management module. The station includes a queue having a first row and a second row. The management module is operable to instruct a first mobile drive unit to move a first group of connected item holders from the second row to the first row, instruct the first mobile drive unit to move the first group of connected item holders along the station such that one or more items stored by the first group of connected item holders are processed at the station, and after the one or more items from the first group of items are processed, instruct a second mobile drive unit to move a second group of connected item holders from the second row to the first row.