System and Method for Maneuvering a Mobile Drive Unit

Abstract

A mobile drive unit is provided for transporting an inventory holder. The mobile drive unit is operable to dock with the inventory holder, move the inventory holder in a first translational direction, and while docked with the inventory holder, selectively rotate the inventory holder while continuing to move in the first translational direction.

What is claimed is: 
     
         1 . A mobile drive unit for transporting an inventory holder, the mobile drive unit operable to:
 dock with the inventory holder;   move the inventory holder in a first translational direction;   while docked with the inventory holder, selectively rotate the inventory holder while continuing to move in the first translational direction.   
     
     
         2 . The mobile drive unit of  claim 1 , the mobile drive unit further operable to rotate in a first rotational direction while selectively rotating the inventory holder in a second rotational direction. 
     
     
         3 . The mobile drive unit of  claim 2 , the mobile drive unit further operable to rotate in the first rotational direction by an amount calculated to cause the mobile drive unit to change from the first translational direction to a second translational direction. 
     
     
         4 . The mobile drive unit of  claim 2 , wherein the first and second rotational directions are different. 
     
     
         5 . The mobile drive unit of  claim 1 , the mobile drive unit further operable to rotate in a first rotational direction at a first rate of movement while selectively rotating the inventory holder in a second rotational direction at a second rate of movement, wherein the first rate of movement and the second rate of movement are different. 
     
     
         6 . The mobile drive unit of  claim 1 , wherein the inventory holder comprises a first face that is orthogonal to the first translational direction and the mobile drive unit is further operable to:
 while continuing translational movement, rotate to a second translational direction while the first face of the inventory holder remains orthogonal to the first translational direction.   
     
     
         7 . The mobile drive unit of  claim 1 , the mobile drive unit further operable to reserve a space for rotation along a path of the mobile drive unit, wherein the space for rotation is reserved based on a physical dimension of the inventory holder. 
     
     
         8 . The mobile drive unit of  claim 7 , the mobile drive unit further operable to selectively rotate the inventory holder while continuing to move in the first translational direction while moving through the reserved space for rotation. 
     
     
         9 . The mobile drive unit of  claim 1 , the mobile drive unit further operable to:
 receive a request to present a selected face of the inventory holder to an inventory station; and   while moving, selectively rotate the inventory holder by an amount calculated to present the selected face to the inventory station.   
     
     
         10 . The mobile drive unit of  claim 1 , the mobile drive unit further operable to:
 move to a location of the inventory holder;   dock with the inventory holder at the location;   move the inventory holder to a destination;   undock with the inventory holder at the destination; and   move away from the inventory holder.   
     
     
         11 . The mobile drive unit of  claim 1 , the mobile drive unit comprising a docking head; and
 the mobile drive unit is further operable to selectively rotate the inventory holder while moving in the first translational direction by independently rotating the docking head, the docking head coupling the inventory holder to the mobile drive unit.   
     
     
         12 . A method for maneuvering a mobile drive unit, comprising:
 docking a mobile drive unit with an inventory holder;   moving the inventory holder in a first translational direction;   while the mobile drive unit is docked with the inventory holder, selectively rotating the inventory holder while continuing to move in the first translational direction.   
     
     
         13 . The method of  claim 12 , further comprising rotating the mobile drive unit in a first rotational direction while selectively rotating the inventory holder in a second rotational direction. 
     
     
         14 . The method of  claim 13 , further comprising rotating in the first rotational direction by an amount calculated to cause the mobile drive unit to change from the first translational direction to a second translational direction. 
     
     
         15 . The method of  claim 13 , wherein the first and second rotational directions are different. 
     
     
         16 . The method of  claim 12 , further comprising rotating the mobile drive unit in a first rotational direction at a first rate of movement while selectively rotating the inventory holder in a second rotational direction at a second rate of movement, wherein the first rate of movement and the second rate of movement are different. 
     
     
         17 . The method of  claim 12 , wherein the inventory holder comprises a first face that is orthogonal to the first translational direction, and the method further comprises:
 while continuing translational movement, rotating the mobile drive unit to a second translational direction while the first face of the inventory holder remains orthogonal to the first translational direction.   
     
     
         18 . The method of  claim 12 , further comprising reserving a space for rotation along a path of the mobile drive unit, wherein the space for rotation is reserved based on the physical dimension of the inventory holder. 
     
     
         19 . The method of  claim 18 , further comprising selectively rotating the inventory holder while continuing to move in the first translational direction while moving through the reserved space for rotation. 
     
     
         20 . The method of  claim 12 , further comprising
 receiving a request to present a selected face of the inventory holder to an inventory station; and   while moving, selectively rotating the inventory holder by an amount calculated to present the selected face to the inventory station.   
     
     
         21 . The method of  claim 12 , further comprising:
 moving the mobile drive unit to a location of the inventory holder;   docking the mobile drive unit with the inventory holder at the location;   moving the inventory holder to a destination;   undocking the mobile drive unit from the inventory holder at the destination; and   moving the mobile drive unit away from the inventory holder.   
     
     
         22 . The method of  claim 12 , the mobile drive unit comprising a docking head and the method further comprises selectively rotating the inventory holder while moving in the first translational direction by independently rotating the docking head, the docking head coupling the inventory holder to the mobile drive unit.