Abstract: A method for fulfilling requests in an inventory system includes receiving a request indicating an activity to be completed. The method also includes selecting a holder to fulfill the request and an inventory station at which to fulfill the request. The inventory station is associated with a queue that includes a plurality of queue spaces. The method further includes moving the selected holder from a first location to a second location remote from the selected inventory station. Additionally, the method also includes determining that a trigger event has occurred and, in response to determining that the trigger event has occurred, moving the selected holder from the second location to a queue space of a queue associated with the selected inventory station.

Abstract: A method for moving one or more mobile drive units within a workspace includes receiving, from a first mobile drive unit, a reservation request requesting use of a first path segment to move in a first direction. The method further includes determining that a second mobile drive unit is currently located on the first path segment and determining whether the second mobile drive unit is moving in the first direction. Additionally, the method includes transmitting a reservation response indicating that the reservation request is denied, in response to determining that the second mobile drive unit is not moving in the first direction. The method also includes transmitting a reservation response indicating that the reservation request is granted, in response to determining that the second mobile drive unit is moving in the first direction.

Abstract: A method of transporting inventory items includes receiving a route request from a mobile drive unit. The route request identifies a destination location within a workspace. The workspace includes at least one cell associated with a first cell attribute and at least one cell that is not associated with the first cell attribute. The method includes determining a state of the mobile drive unit. The method also includes generating a path to the destination location for the mobile drive unit that traverses cells associated with the first cell attribute, in response to determining that the mobile drive unit is associated with a first state. The method includes generating a path to the destination location for the mobile drive unit that does not traverse cells associated with the first cell attribute, in response to determining the mobile drive unit is not associated with the first state. The method further includes transmitting the path to the mobile drive unit.

Abstract: A method for transporting inventory items includes determining an assignment state of a mobile drive unit. The method also includes selecting a location for the mobile drive unit based on the assignment state of the mobile drive unit, in response to determining that the mobile drive unit is not currently completing a task. The method further includes transmitting information to the mobile drive unit identifying the selected location.

Abstract: A method for transporting inventory items includes moving a mobile drive unit to a first point within a workspace. The first point is a location of an inventory holder. The method further includes docking the mobile drive unit with the inventory holder and moving the mobile drive unit and the inventory holder to a second point within the workspace. The second point is associated with conveyance equipment. The method further includes moving the inventory holder to a third point within the workspace using the conveyance equipment.

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.

Abstract: A method for moving a mobile drive unit within a workspace includes receiving a path. The path includes at least an initial segment and one or more additional segments. The initial segment includes a portion of the path adjacent to the first point; and at least one of the additional segments includes a portion of the path adjacent to the second point. The method further includes storing the path, reserving the initial segment of the path, and moving away from the first point along the initial segment. After initiating movement along the initial segment, the method includes reserving each of the additional segments of the path and moving toward the second point along each of the additional segments while that segment is reserved.