Abstract:
A system for automated management of a high density storage facility which contains shelves having multiple containers containing products stored therein. The system uses an autonomous mobile robot and a lifting frame. The lifting frame includes several supports, members, and crossbars along with storage ledges. The lifting frame includes a gripping device and a lifting device, which provides motive power to the shelves.

Description:
Priority Claim 
       [0001]    This application claims priority to a U.S. Provisional Application Ser. No. 62/302,070, filed on Mar. 1, 2016, presently pending. This application also claims priority as a continuation in part of PCT application PCT/US2016/039010, filed on Jun. 23, 2016, presently pending, which in turn claimed priority to U.S. provisional application Ser. No. 62/231,092, filed on Jun. 24, 2015, presently expired, and U.S. provisional application Ser. No. 62/302,070, filed on Mar. 1, 2016, presently pending. The contents of each application are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention. 
         [0003]    The field of the invention is a system for automation of a warehouse employing a mobile robotic frame and a power transfer system. The combination comprises an improved automated storage and retrieval system. 
         [0004]    2. Background of the Invention. 
         [0005]    In various embodiments, the invention provides a solution for automating a storage location which includes non-powered shelves. The storage location can be any job site with an inventory, such as a fulfillment center, a warehouse, or a distribution center. 
         [0006]    In one embodiment, the invention comprises a mobile robot, which moves containers from one or more mobile frames. The frames include lifting devices and gripping devices to move containers to and from warehouse shelves. Each shelf includes a passive container movement system which is actuated by a robotic arm attached to the mobile frame. The robotic arm works in cooperation with a gripping device, also located on the mobile frame. 
         [0007]    Traditionally, warehouse automation systems required large mobile robotic components which could not be deployed even if the initial warehouse design or infrastructure did not account for robotic components. 
         [0008]    A need exists in the art for a system that allows for adding of a relatively low-cost robotic solution to a warehouse having passive shelving units. 
         [0009]    SUMMARY OF INVENTION 
         [0010]    An object of the invention is to create a system for automating a warehouse. A feature of the invention is that the lifting device from the moveable frames retrieves needed containers from warehouse shelves and makes them available to a mobile robot for processing. An advantage of the system is that it allows for automated deliveries within a warehouse setting without custom-built infrastructure within the warehouse. 
         [0011]    A further object of the invention is to automate a warehouse without adding powered movement mechanisms to each shelf. A feature of the invention is that the lifting device which is included on the moveable frame includes a shelf power transfer unit which actuates a shelf movement mechanism. An advantage of the invention is that it allows for automation of a warehouse without adding complexity and power systems to each shelf. A system for automated management of a high density warehouse comprising: warehouse shelves having multiple containers containing products stored thereon, wherein each shelf comprises a container movement mechanism; an autonomous mobile robot; and a lifting frame having one or more floor supports, vertical members, at least one horizontal crossbar, one or more storage ledges intermediate said floor supports and said at least one horizontal crossbar, further said lifting frame having a gripping device suspended from said at least one crossbar wherein said frame gripping device comprises a gantry arm wherein said gantry arm receives containers from the autonomous mobile robot to place on one or more frame ledges, wherein said gantry arm returns containers to the autonomous mobile robot from one or more frame ledges, and a lifting device attached to at least one vertical member, wherein said lifting device comprises an articulated arm having at least container placement tool wherein said lifting device transfers containers from one or more frame storage ledges to and from one or more warehouse shelves. 
     
    
     
       BRIEF DESCRIPTION OF DRAWING 
         [0012]    The invention together with the above and other objects and advantages will be best understood from the following detailed description of the preferred embodiment of the invention shown in the accompanying drawings, wherein: 
           [0013]      FIG. 1  depicts an overview of the system pursuant to one embodiment of the invention; 
           [0014]      FIG. 2  depicts an overview of an embodiment of an end of arm tool pursuant to one embodiment of the invention; 
           [0015]      FIG. 3  depicts an overview of a gripping device pursuant to an embodiment of the invention; 
           [0016]      FIG. 4  depicts a detailed view of an embodiment of the transmission point of an invention; 
           [0017]      FIG. 5  depicts an overview of a product loading point pursuant to one embodiment of the invention; 
           [0018]      FIGS. 6A-D  depict an overview of power transfer alternatives pursuant one embodiment of the invention; 
           [0019]      FIGS. 7A-B  depict alternative shelf embodiment pursuant to the invention; 
           [0020]      FIG. 8  depicts a schematic overview of an embodiment of the system as deployed in a facility; 
           [0021]      FIG. 9  depicts an overview of the primary elements of one embodiment of the system; 
           [0022]      FIG. 10  depicts an overview of a component of one embodiment of the system; 
           [0023]      FIG. 11  depicts a detailed view of joining of components in one embodiment of the system; 
           [0024]      FIG. 12  depicts another view of joining of components in one embodiment of the system; 
           [0025]      FIG. 13  depicts an overview of another component of one embodiment of the system; and 
           [0026]      FIG. 14  depicts an overview of another component of one embodiment of the system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. 
         [0028]    To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware circuitry. Thus, for example, one or more of the functional blocks (e.g. processors or memories) may be implemented in a single piece of hardware (e.g. a general purpose signal processor or a block of random access memory, hard disk or the like). Similarly, the programs may be stand-alone programs, may be incorporated as subroutines in an operating system, may be functions in an installed software package, and the like. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings. 
         [0029]    As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. 
         [0030]    Turning to the figures,  FIG. 1 , depicted therein is an overview  10  of the invented system. The system comprises a series of warehouse shelves  12 , each shelf having a shelf front  22 . Containers  18  of products are stored on each shelf. To access the containers  18 , a moveable frame  20  approaches the shelf fronts  22 . The moveable frame  20  includes a lifting device  14 , such as the robotic arm shown in  FIG. 1 . The moveable frame  20  also includes a gripping device  16 , capable of moving in any direction within the moveable frame  20 . The moveable frame  20  includes a storage ledge  26 . 
         [0031]    In use, the moveable frame  20  approaches a bank of shelves  12 . The ledge  26  moves into the required position to match the height of the shelf front  22 . The lifting device  14  retrieves containers from the ledge  26  and places them on the shelf  12 . While the lifting device  14  is placing containers, the gripping device  16  is arranging containers on the ledge  26  to allow the lifting device  14  to place containers  18 . Once all containers are placed or retrieved form the shelf  12 , the ledge  26  lowers and the containers  18  are retrieved by the mobile robot  24 . The moveable frame  20  thereafter moves to a different bank of shelves. 
         [0032]    As shown in  FIG. 2 , the lifting device  14  includes an end of arm tool (EOAT) which allows the lifting device  14  to interact with containers  18 . The end of arm tool in  FIG. 2  comprises forks  36  and suction cups  38 . The details of the operation of the gripping device  16  are shown in  FIG. 3 , while details of the top of the shelf rack are shown in  FIG. 4 .  FIG. 5  shows the exchange point  42  between the mobile robot  24  and the mobile frame  20 . 
         [0033]    Turning to the shelf power transfer options, as shown in  FIGS. 6A-D , containers  18  move along the shelf  12  using a mechanism. As shown in  FIG. 6A , the mechanism comprises a shelf sprocket  50  which is driven by a lifting device  14  end of arm tool sprocket  52 . The shelf  12  mechanism also includes a pulley  54 . By moving its sprocket  52 , the lifting device  14 , which includes an end of arm tool  15 , can move the containers  18  on the shelf  12 , even though the shelf does not include any autonomous power. Products from the end of arm tool belt  56  are transferred to the shelf  12 . The belt  56  is supported by the forks  36 . As can be seen in  FIG. 6A , the shelf  12  is substantially parallel to the floor of the warehouse. 
         [0034]    In the alternative design shown in  FIG. 6C , the lifting device  14  includes a moveable rod  70  which includes one or more fingers  74 . The rod  70  is rotated in place and fingers  74  are moved in place such that when the rod  70  is moved in the direction w product containers  18  move in the direction w. 
         [0035]    An alternative embodiment of the shelf  12  power transfer mechanism is shown in  FIG. 6B . The mechanism comprises a lifting device end of arm tool  15  which includes a powered rotating shank  62  having an irregular cross-section. The shank  62  is removably received by the shelf actuator  64 , such that rotational motion of the shank  62  is translated into lateral motion of the shelf  12  resulting in movement of the containers  18 . As shown in  FIG. 6D , the lifting device  14  product placement tool includes a rod controller  76  having selective appendage activator  78 . In one embodiment, the appendage activator  78  comprises gripper fingers. 
         [0036]    Several alternative shelf  12  concepts are shown in  FIGS. 7A-B . The embodiments shown in  FIGS. 7A-B  are designed to work with gravity-assisted flow racks. 
         [0037]    In the various depicted embodiments, a benefit of system which includes the moveable frame  20 , also referred to as the roboframe is that it can reliably process, place, and pick containers in a technically challenging environment. For example, the roboframe compensates for uneven floors, misaligned racks, and other environmental issues. The roboframe and devices attached to it include onboard sensors to adjust the operation of the devices. Therefore, the use of the roboframe does not require a retrofit of the warehouse, nor does it require extensive repairs to a warehouse. 
       System Overview 
       [0038]    Turning to  FIG. 8  depicted therein is a top-down schematic overview of a facility which uses an embodiment of the system. The facility  100  is shown as using a larger aisle  102  and a series of smaller aisles  104 . The larger aisle  102  facilitates movement in two directions by mobile robots  110 . As will be discussed in detail below, each mobile robot  110  is equipped with a platform for transporting of bins, trays, carts, racks, and other product payload containers. 
         [0039]    The larger aisle  102  acts a type of a mobile robot  110  thoroughfare with markings  103 , both visible and invisible, designed to guide the mobile robots  110  and to assist the mobile robot  110  sensors in determining each robot&#39;s location within the premises  100 . 
         [0040]    The narrower aisles  104  separate shelving units or racks  106 .  FIG. 8  depicts the shelving units  106  predominantly as empty, but that is only for purposes of clarity of the figure. One region  108  of the shelving spaces is shown as filled with containers  112  of various sizes. 
         [0041]    The narrower aisles  104  are used by roboframes  120 , which will be described in detail herein. Each roboframe  120  moves in an aisle  104  to reach a particular storage location within a rack  106 . Each roboframe includes an area  122  where a mobile robot  110  can deposit its payload. The roboframe, using components described below, interacts with individual racks  106  to facilitate movement of product from each rack  106  to a roboframe  120  which is then received by a mobile robot  110  for further delivery or processing. Analogously, the roboframe  120  allows for movement of product from a mobile robot  110  to a roboframe  120  and then to a specific location on a rack  106 . 
         [0042]    While in  FIG. 8 , each narrow aisle  104  is shown as occupied by a roboframe  120 , in one embodiment, a single roboframe  120  interacts with multiple aisles  104 . 
         [0043]    The facility  100  also includes a guard  109  to prevent unauthorized entry to the area occupied by roboframes  120  and mobile robots  110 . This guard  109  ensures that the autonomous systems can operate presuming that unauthorized persons will not enter the area. This increases the throughput of the system and allows the various components to eliminate sensors which would otherwise be needed to detect personnel and stop the autonomous components to prevent collisions. The guard  109  includes openings to allow mobile robots to pass through the perimeter, and one or more portals  111  to allow the roboframes  120  to enter the aisles  104 . 
         [0044]    As shown in  FIG. 8 , the mobile robots  110  transport product containers between roboframes  120  and with external product storage points. The products are stored in totes, as well as bins, and trays. Each container system employs computer-readable identifiers to allow for real-time tracking of product locations. In one embodiment, the mobile robots  110  include a scale which allows for cross-checking of whether or not the expected product weight has been met. 
         [0045]    As will be described fully below, the shelving or racks  106  used by the system are low cost, have few components (none of which are powered) and can be adjusted to various heights. The racks  106  can be expanded as needed and reconfigured to carry product containers  112  of various shapes and sizes. 
       Roboframe and Rack Details 
       [0046]    Turning to  FIG. 9 , shown therein are the details of the roboframe  120  and rack  106  and containers  112 , shown in  FIG. 8 . While a single rack  106  is shown in  FIG. 9 , as can be appreciated form the schematic overview of  FIG. 8 , the system is designed to operate with many racks connected together, and with the roboframe  120  surrounded on both sides by arrays of racks  106 . Also visible in  FIG. 9  is the mobile robot  110 , as it travels to the roboframe  120 . 
         [0047]    Turning first to the roboframe  120 , the roboframe  120  is built from several vertical members  124  and a pair of top horizontally extending members  126 . The vertical members  124  are attached to a mobile base  128 , which includes wheels  130  and sensors  132  at each corner of the base  128 , in one embodiment. The sensors include lidar, RF-tag readers, and the like. The sensors  132  also include a warning light, a buzzer, or other indicator, to warn of expected movement of the roboframe  120 . While the sensors are placed on corners of the roboframe  120 , as shown in  FIG. 9 , the roboframe base  128  is not exactly rectangular, with most corners having a rounded feature to facilitate turning of the roboframe  120 . In one embodiment, additional sensors are located in other components of the roboframe  120 , such as encoders in the wheels, which assist the roboframe in determining its relative location. 
         [0048]    The wheels  130  comprise an irregular shape with compressible features to prevent slippage of the roboframe  120  while it is loaded with product. The wheels  130  are designed for travel along a relatively flat surface, as may be found in a distribution center. In one embodiment, a mecanum all wheel drive mechanism is used, which allows the wheels to move in any direction. The wheels are highly precise and the location of the roboframe  120  is determined using steering accuracy, with no floor-based guidance systems required, in one embodiment. The wheels provide sufficient padding to prevent transferring force to the guide rail  138 . 
         [0049]    In one embodiment, the roboframe  120  is tethered to a power source, such as a buss bar or umbilical. Communications between the roboframe  120  and a central operations system is accomplished using wireless communications. 
         [0050]    The top horizontal members  126  of the roboframe also include guide stabilizers  136 , which engage with guiderails  138  found near or on the top of the rack  106 . The guide stabilizers  136  use a quick connect system to engage with the guide rails  138 . In one embodiment, the guide rails  138  further comprise a pair of conductors so as to provide power to the roboframe  120  components. The guide stabilizers  136  include corresponding conductors to make contact with the guide rail  138  energized conductors. The guide rail  138  in another embodiment includes an induction coil to transfer energy to the guide stabilizers  136  without direct physical connection between the two components. 
         [0051]    In operation, the roboframe  120  travels to a rack  106  location, the clamp guide stabilizers  136  engages with the guide rail  138 , the roboframe  120  performs its functions as described below, and the clamp guide stabilizers  136  release. The roboframe  120  then travels to the next location. In one embodiment, the rail  138  is mounted directly to a wall or other physical component. The design of the rail  138  is such that the roboframe  120  can be deployed even if there no racks for interaction, such as at the end of an aisle or in a stand-by area. The design is such that rails  138  may be daisy chained in order to get continuous support and power transfer down the length of the facility aisle. 
         [0052]    The mobile base  128  includes an area  122  dedicated to interactions with the mobile robot  110 . In the embodiment shown in  FIGS. 8 and 9  the area  122  comprises rollers where mobile robots  110  can retrieve or deposit payloads  112 . During the time a mobile robot  110  interacts with the area  122 , an engagement arm  142  holds the mobile robot  110  in place. When depositing payloads  112 , the mobile robot  110  engages its conveyor to move the payload from the mobile robot  110  to the area  122 . The area  122  includes multi-directional conveyors, such as rollers, balls, or the like. The area  122  conveyor shifts the payload to the left and clearing a portion of the area  122  for a different payload which is to ready to be picked up. When the mobile robot  110  is being provided the payload  112 , the area  122  conveyors move a payload stack to the mobile robot  110  held in place by the engagement arm  142 . 
         [0053]    A platform  140  moves along any vertical position of the vertical members  124 . 
         [0054]    Each corner of the platform  140  engages with a corresponding vertical member  124 . In one embodiment, the engagement mechanism comprises a rail with corresponding wheels to engage the rail. In another embodiment, each corner uses a pair of ratchet wheels which engage one another and are locked in place with a pawl. In yet another embodiment, a twisting type mechanism is used. 
         [0055]    While in one embodiment each corner includes a powered mechanism to support movement, in another embodiment, only a pair of opposing corners of the platform  140  include active movement mechanisms. In this embodiment, the remaining corners act to balance the platform  140 . 
         [0056]    In every embodiment, the platform  140  is maintained as substantially parallel to the top horizontal members  126 . 
         [0057]    The platform is divided into several logical areas. In one embodiment, the part of the platform closest to the mobile robot area  122  is the stack buffer  144 . Items in the stack buffer  144  are manipulated by the gantry  146 , which moves up and down within the moving platform  140 , picking payloads up from one end of the platform and moving the payloads to other parts of the platform, as well as stacking the payloads one on top of another. 
         [0058]    The gantry  146  includes a hook-based mechanism to engage with corners of the payload containers, in one embodiment. In another embodiment, the gantry  146  also includes an electromagnet. 
         [0059]    The gantry  146  moves the payload containers to the part  148  of the platform  140  which is furthest away from the mobile robot area  122 . That part  148  of the platform is where the robotic arm  150  interacts with the payloads. The robotic arm  150  retrieves containers from its area  148 , loads them to the robotic end of arm tool  152  and transfers them to or from the rack  106 . The end of arm tool  152  is discussed in detail below. 
         [0060]    The platform  140  moves with the robotic arm  150  and its primary responsibility is the creation of stacks to be loaded by the end of arm tool on the robotic arm  150 . Stacks of payloads are exchanged with the mobile robot while the platform  140  is lowered to the mobile base  128  and the mobile robot  110  is docked with the roboframe  120 . In one embodiment, the maximum weight per stack is 100 to 500 pounds. 
         [0061]    The robotic arm  150  includes two joints capable of rotational motion and a wrist joint which controls the end of arm tool  152 . 
         [0062]    In one embodiment, the robotic arm  150  is mounted at a fixed base  154  on the platform  140 . In another embodiment, the robotic arm  150  base  154  can move up and down the sides of the platform  140 . In this embodiment, the joints on the robotic arm do not require the same degree of freedom of movement as on the embodiment where the robotic arm  150  is fixed in place. 
         [0063]    A robotic arm  150  mounted on the platform  140  includes sensors, such as cameras mounted on its wrist and end of arm tool. The robotic arm  150  uses the sensors to determine when to transfer payloads from the platform  140  area  148  to the end of arm tool  152 . The robotic arm  150  has sufficient freedom of movement in its joints to reach up to four columns of product and process both sides of the narrow aisle  104  shown in  FIG. 8 . 
         [0064]    In one embodiment, the maximum weight of a payload, such as a tray or a bin is 50 pounds, which is dictated by the carrying capacity of the platform  140 , gantry  146 , and robotic arm  150 . As the robotic arm  150  must accommodate not only a payload, but also its sophisticated end of arm tool  152 , its carrying limit is the determining factor for total system capacity in most embodiments. 
         [0065]    Having access to both sides of an aisle, the robotic arm  150  can access up to  640  trays in one configuration. In operation, the payloads the robotic arm  150  requires are be arranged by the gantry  146  in the robotic arm area  148 . 90% of payload containers that are needed are found in the robotic arm area  148 . The few containers that are not in an expected location are moved to the area  148  by the gantry  146 . 
         [0066]    In many circumstances, when the robotic arm  150  is retrieving containers from the rack  106 , the items are found in the front of the rack  106 . However, the robotic arm will use a set down process and place item in its area  148  from the rack  106  when the robotic arm must retrieve an item from the back of the shelf on a rack  106 . In this set down process, the gantry moves items from the arm area  148  to the buffer area  144 , freeing up space for the robotic arm to transfer payloads from the rack  106 . 
         [0067]    In one embodiment, the cycle times for the system are as follows.  15  seconds to pick a tray from the stack found in the robotic arm area  148 , transfer the tray to the robotic arm  150  end of arm tool  152 , and transfer the item to the rack  106 . Similarly, the robotic arm  150  requires  15  seconds to pick a tray from the rack  106  transfer to the end of arm tool  152 , and move to the stack of items in the area  148 . 
       End of Arm Tool 
       [0068]    The interaction of the end of arm tool  152  and the rack  106  is shown in  FIG. 10 . The end of arm tool  152  is mounted to the wrist of the robot  150 . The end of arm tool comprises a cage like structure  155  with top  156  and bottom  158  substrates. While the top  156  and bottom  158  substrates are substantially identical in one embodiment, in another embodiment, the substrates  156 ,  158  have different configurations. Each substrate also includes weight saving openings  160 . However, the substrates  156 ,  158  contain sufficiently rigid materials to prevent deformation of the cage  155 . 
         [0069]    Similarly to the substrates  156 ,  158 , the cage  155  sides  162  comprise as little material as possible, while ensuring structural stability for the cage  155 . As is shown in detail in the remaining figures, the cage  155  encloses two conveyors  164 ,  166  which are independently operated, in one embodiment. The conveyors  164 ,  166  transfer payloads from the end of arm tool  152  back to the platform  140  described above, or to the rack  106 . 
         [0070]    The conveyors  164 ,  166  are powered by a mechanism  168 , such as a motor connected to a differential which in turn transfers motion to the wheels of each conveyor  164 ,  166 . 
         [0071]    Overall, the end of arm tool has a simple design with a minimal number of powered active components. In one embodiment, only the mechanism  168  for the conveyors  164 ,  166  is a powered component, the remaining elements being passive. 
         [0072]    The end of arm tool with wide conveyors and other features described below, provides a large tolerance for misalignment. Therefore, the robotic arm  150  does not need to move the end of arm tool  152  with extreme precision. 
         [0073]    The details of the interaction of the end of arm tool  152  and a rack  106  are shown in  FIG. 11 . The end of arm tool  152  includes hooks  170  which engage with apertures  172  on each shelf comprising the rack  106 . During alignment of the end of arm tool  152  with the rack  106 , the hooks  170  engage the sides of the apertures, which include profiles to guide the hooks  170  into proper alignment with the apertures  172 . 
         [0074]    In one embodiment, a low voltage continuity sensor determines once the hooks  170  have made contact with the rack  106  apertures  172 . In another embodiment, the end of arm tool  152  sensors, such as a camera, determine when the end of arm tool  152  has been aligned with the rack  106 . 
         [0075]    The end of arm tool  152  includes an array of six drive wheels  174 , which engage with a drive area  176  on an axle  178  of a shelf conveyor  180 . The wheels  174  transfer motion to the shelf moving the shelf conveyor  180  in either direction. The motion of the wheels  174  is created by a friction drive motor  182  mounted on the end of arm tool  152 . 
         [0076]    In as much as the power transfer mechanism uses an array of six wheels  174 , and the six wheels  174  engage a wide friction area  176 , the two components of the system do not need to be exactly aligned. Further, a space between the conveyor on the end of arm tool  152  and the shelf conveyor  180  is permissible, so long as the space is not large enough to allow a payload to become stuck between the two conveyors. 
         [0077]    Another view of the six wheel  174  assembly is depicted in  FIG. 12 . As shown in that embodiment, the six wheel assembly  174  includes a top motor  182  and a bottom motor  184 . In other embodiments, not all wheels a powered by a motor, with only a single source of movement used. 
         [0078]    As can be appreciated from  FIGS. 11 and 12 , the rack  106  includes no powered components. Instead, the shelf conveyor  180  is entirely passive with all motion of that shelf being the responsibility of the end of arm tool  152 . 
         [0079]    As shown in  FIG. 12 , one corner of the end of arm tool  152  includes a camera  186 . In other embodiments, not shown, additional sensors are mounted to the end of arm tool. The camera  186  is used to align the end of arm tool with the rack  106 . 
         [0080]    While the discussion above involved the interaction between the end of arm tool  152  and the rack  106 , analogous structures are found on the platform  140  and so the end of arm tool  152  engages with the platform  140  in a similar fashion. 
         [0081]    In one embodiment, the end of arm tool includes identical hooks  170  and wheel  174  assemblies on each side of the end of arm tool so as to allow interaction of the end of arm tool with either side of the rack  106  or moving platform  140 . 
         [0082]    In use, the end of arm tool can independently interact with up to two sets of containers at a time, as the end of arm tool has two independent conveyors  164 ,  166  (shown in  FIG. 10 ). An end of arm tool loaded with one payload, can travel to a shelf, pick up another container from a shelf, rotate the arm tool by 180 degrees, and then put the second container on the same shelf. In this way, the end of arm tool can replace containers with only one full motion of the robotic arm. 
         [0083]    Similarly, the robotic arm can swap containers and reverse their order on the shelf. In this process, the robotic arm starts with an empty end of arm tool, loads a first container, rotates by 180 degrees the tool to the empty side, loads a second container, rotates the tool again, then returns the first container to the shelf, followed by the second container. In this process the robotic arm can reverse the order of items on the rack without using any intermediate storage, such as the platform  140 . 
         [0084]    Further, the robotic arm can swap containers across aisles by picking a payload from one side and a second side of the aisle, then changing the container&#39;s positions. 
         [0085]    The benefits of the end of arm tool arrangement include a decrease in the stacking and de-stacking of product containers on buffer areas of the platform and a decrease in the operations required by the gantry tool. 
       Rack Overview 
       [0086]    An overview of the rack  106  pursuant to one embodiment of the invention is shown in  FIG. 13 . The rack  106  is designed with shelves for totes  190  and trays  192 . Each rack  106  shelf has a front  194  which is the only point at which the roboframe interacts with the rack  106 . The frame includes marks  196  to assist in alignment of the end of arm tool, which is equipped with a camera. 
         [0087]    Shelves which comprise the rack  106  are individually serviceable and replaceable. The shelves conveyors  180  do not have powered components, with all the motion being originated with the end of arm tool. The shelves are adjustable for different container heights, with the largest containers being reserved for the top-most shelf. 
         [0088]    Each shelf conveyor  180  includes a frictional engagement surface on the side facing the payloads to ensure that the payloads do not shift during storage. The reverse side of the conveyor  180  includes a low friction strip. This allows the conveyor  180  to move up to several hundred pounds of payloads that are located on the shelf. 
       Robotic Arm Operation 
       [0089]    The details of the operation of the robotic arm  150  are shown in  FIG. 14 . As described above, the robotic arm  150  is mounted on a platform  154 , attached to the roboframe  120 . 
         [0090]    As shown in the embodiment of  FIG. 14 , the robotic arm  150  comprises a stationary base  154  with a rotating base plate  200  installed thereon. The base plate  200  allows the robotic arm  150  to extend from one aisle to the other aisle without fully extending all the joints of the robotic arm. In a fully-extended configuration, the maximum weight which can be supported by the joints decreases. During movement of the roboframe, the robotic arm  150  is placed in an extended position substantially parallel with the roboframe. In this configuration, pressure on the arm joints is minimized. Further, the end of arm tool is aligned so as to not extend beyond the sides of the roboframe  120 . 
         [0091]    Attached to the rotating base plate  200  is the arm base  202  with counterweights  206 . On the opposing end of the arm base  202  is a revolute joint  204 , which controls the movement of the first link  208 . The revolute joint  204  allows the arm to move closer or away from the roboframe  120 . 
         [0092]    The first link  208  has a substantially rectangular profile, in one embodiment. In another embodiment, the first link  208  has an I-beam profile. 
         [0093]    The opposing end of the first link  208  is a second revolute joint  210 . The second revolute joint  210  connects the first link  208  to the second link  212 . 
         [0094]    The second link  212  is substantially cylindrical, in the depicted embodiment. The second link  212  includes a number of sensors. While the shapes of the first link and second link are depicted as rectangular and cylindrical respectively, a number of shapes for the links is envisioned in other embodiments, not shown. 
         [0095]    The end of the second link  212  which is opposite of the second revolute joint  210  ends in a wrist joint  214 . The wrist joint  214  allows for rotation of the end of arm mounting plate  216  in any direction. The end of arm tool  152  (shown only partially in  FIG. 14 ) is attached to the end of arm mounting plate  216 . 
         [0096]    This arrangement allows the robotic arm  150  to move in any number of directions, and reach either aisle  104 , as shown in  FIG. 8 . 
         [0097]    Although exemplary implementations of the invention have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims. 
         [0098]    It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the invention, they are by no means limiting, but are instead exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.