Warehouse with a storage and retrieval system

BACKGROUND

1. Field

0001The invention relates to the field of warehouse storage and retrieval systems according to the preamble of claim 1.

2. Brief Description of Related Developments

0002Warehouses for storing case units may generally comprise a series of storage racks that are accessible by transport devices such as, for example, fork lifts, carts and elevators that are movable within aisles between or along the storage racks or by other lifting and transporting devices. These transport devices may be automated or manually driven. Generally the case units stored on the storage racks are contained in carriers, for example storage containers such as trays, totes or shipping cases, or on pallets. Generally, incoming pallets to the warehouse (such as from manufacturers) contain shipping containers (e.g. cases) of the same type of goods. Outgoing pallets leaving the warehouse, for example, to retailers have increasingly been made of what may be referred to as mixed pallets. As may be realized, such mixed pallets are made of shipping containers (e.g. totes or cases such as cartons, etc.) containing different types of goods. For example, one case on the mixed pallet may hold grocery products (soup can, soda cans, etc.) and another case on the same pallet may hold cosmetic or household cleaning or electronic products. Indeed some cases may hold different types of products within a single case. Conventional warehousing systems, including conventional automated warehousing systems do not lend themselves to efficient generation of mixed goods pallets. In addition, storing case units in, for example carriers or on pallets generally does not allow for the retrieval of individual case units within those carriers or pallets without transporting the carriers or pallets to a workstation for manual or automated removal of the individual case units. <patcit id="pcit0001" dnum="EP1627830A1"><text>EP1627830A1</text></patcit> discloses a system according to the preamble of claim 1.

0003It would be advantageous to have a storage and retrieval system for efficiently storing and retrieving individual case units without containing those case units in a carrier or on a pallet.

0004The invention is defined by the features of claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

0005The foregoing aspects and other features of the disclosed embodiments are explained in the following description, taken in connection with the accompanying drawings, wherein: <ul id="ul0001" list-style="none"><li><figref idref="f0001">Fig. 1</figref> schematically illustrates an exemplary storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0002 f0003 f0004">Figs. 2-4</figref> illustrate schematic plan views of storage and retrieval systems having different configurations in accordance with the exemplary embodiments;</li><li><figref idref="f0005">Fig. 5</figref> illustrates a structural portion of a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0006">Figs. 6A</figref> and <figref idref="f0007">6B</figref> illustrate storage shelves in accordance with an exemplary embodiment;</li><li><figref idref="f0008">Figs. 7A and 7B</figref> illustrate schematic views of a conveyor system in accordance with an exemplary embodiment;</li><li><figref idref="f0009">Fig. 8</figref> illustrates a schematic view of a conveyor shelf in accordance with an exemplary embodiment;</li><li><figref idref="f0010 f0011">Figs. 9A-9D</figref> schematically illustrate a transfer station in accordance with an exemplary embodiment;</li><li><figref idref="f0012">Figs. 10</figref>, <figref idref="f0013">11A</figref>, <figref idref="f0013">11B</figref> and <figref idref="f0014">11C</figref> illustrate a transport robot in accordance with an exemplary embodiment;</li><li><figref idref="f0015">Figs. 12A</figref> and <figref idref="f0016">12B</figref> illustrate partial schematic views of the transport robot of <figref idref="f0012">Figs. 10</figref>, <figref idref="f0013">11A and 11B</figref> in accordance with an exemplary embodiment;</li><li><figref idref="f0017">Fig. 13</figref> schematically illustrates a control system of the transport robot of <figref idref="f0012">Figs. 10</figref>, <figref idref="f0013">11A and 11B</figref> in accordance with an exemplary embodiment;</li><li><figref idref="f0018">Fig. 14</figref> schematically illustrates exemplary operational paths of a transport robot in accordance with the exemplary embodiments;</li><li><figref idref="f0019">Fig. 15A</figref> illustrates a conventional organization of item storage in a storage bay;</li><li><figref idref="f0019">Fig. 15B</figref> illustrates an organization of case units in a storage bay in accordance with an exemplary embodiment;</li><li><figref idref="f0019">Fig. 15C</figref> illustrates a comparison of unused storage space between the item storage of <figref idref="f0019">Fig. 15A</figref> and the item storage of <figref idref="f0019">Fig. 15B</figref>;</li><li><figref idref="f0020">Fig. 16</figref> schematically illustrates a control system of a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0021">Fig. 17</figref> illustrates a portion of the control system of <figref idref="f0020">Fig. 16</figref> in accordance with an exemplary embodiment;</li><li><figref idref="f0022">Fig. 18</figref> illustrates a control schematic for a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0023">Fig. 18A</figref> schematically illustrates a portion of the control system of <figref idref="f0020">Fig. 16</figref> in accordance with an exemplary embodiment;</li><li><figref idref="f0024">Fig. 18B</figref> illustrates a resource reservation queue in accordance with an exemplary embodiment;</li><li><figref idref="f0025">Fig. 19</figref> schematically illustrates a portion of the control system of <figref idref="f0020">Fig. 16</figref> in accordance with an exemplary embodiment;</li><li><figref idref="f0026">Fig. 20</figref> is a schematic illustration of a portion of a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0027">Fig. 21</figref> schematically illustrates a portion of the control system of <figref idref="f0020">Fig. 16</figref> in accordance with an exemplary embodiment;</li><li><figref idref="f0028">Fig. 22</figref> is a schematic illustration of a portion of a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0029">Fig. 23</figref> is a schematic diagram illustrating traffic management in a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0030">Figs. 24A and 24B</figref> are schematic diagrams illustrating transport robot communications in accordance with an exemplary embodiment;</li><li><figref idref="f0031">Fig. 25</figref> is a schematic illustration of bot traffic management in accordance with an exemplary embodiment;</li><li><figref idref="f0032">Fig. 26</figref> is a schematic illustration of a simplified floor plan of an order picking facility in accordance with an exemplary embodiment;</li><li><figref idref="f0033">Fig. 27</figref> is a schematic diagram of an exemplary flow of case units through a storage and retrieval system in accordance with an exemplary embodiment;</li><li><figref idref="f0034">Fig. 28</figref> is a schematic illustration of a method in accordance with an exemplary embodiment; and</li><li><figref idref="f0035">Figs. 29</figref> and <figref idref="f0036">30</figref> are flow diagrams of exemplary methods in accordance with the exemplary embodiments.</li></ul>

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT(S)

0006<figref idref="f0001">Fig. 1</figref> generally schematically illustrates a storage and retrieval system 100 in accordance with an exemplary embodiment. Although the embodiments disclosed will be described with reference to the embodiments shown in the drawings, it should be understood that the embodiments disclosed can be embodied in many alternate forms. In addition, any suitable size, shape or type of elements or materials could be used.

0007In accordance with one exemplary embodiment the storage and retrieval system 100 may operate in a retail distribution center or warehouse to, for example, fulfill orders received from retail stores for case units (where case units as used herein means items not stored in trays, on totes or on pallets, e.g. uncontained). It is noted that the case units may include cases of items (e.g. case of soup cans, boxes of cereal, etc.) or individual items that are adapted to be taken off of or placed on a pallet. It is also noted that the term "freely arranged items" will be referred to herein as "items" for explanatory purposes. In accordance with the exemplary embodiments, shipping cases or case units (e.g. cartons, barrels, boxes, crates, jugs, or any other suitable device for holding items) may have variable sizes and may be used to hold items in shipping and may be configured so they are capable of being palletized for shipping. It is noted that when, for example, pallets of case units arrive at the storage and retrieval system the content of each pallet may be uniform (e.g. each pallet holds a predetermined number of the same item - one pallet holds soup and another pallet holds cereal) and as pallets leave the storage and retrieval system the pallets may contain any suitable number and combination of different case units (e.g. each pallet may hold different types of case units - a pallet holds a combination of soup and cereal). In alternate embodiments the storage and retrieval system described herein may be applied to any environment in which case units are stored and retrieved. The storage and retrieval system 100 may be configured for installation in, for example, existing warehouse structures or adapted to new warehouse structures. In one exemplary embodiment, the storage and retrieval system may include in-feed and out-feed transfer stations 170, 160, multilevel vertical conveyors 150A, 150B, a storage structure 130, and a number of autonomous vehicular transport robots 110 (referred to herein as "bots"). In alternate embodiments, the storage and retrieval system may also include robot or bot transfer stations 140 (<figref idref="f0010 f0011">Figs. 9A-9D</figref>), which may be located in transfer areas 295 of the storage and retrieval system. The in-feed transfer stations 170 and out-feed transfer stations 160 may operate together with their respective multilevel vertical conveyors 150A, 150B for transferring case units to and from one or more levels of the storage structure 130. It is noted that while the multilevel vertical conveyors are described herein as being dedicated inbound conveyors 150A and outbound conveyors 150B, in alternate embodiments each of the conveyors 150A, 150B may be used for both inbound and outbound transfer of case units/items from the storage and retrieval system. In one exemplary embodiment, the bots 110 may interface directly with the multilevel vertical conveyors 150A, 150B as will be described below while in alternate embodiments the bots 110 may interface indirectly with the multilevel vertical conveyors 150A, 150B through, for example, respective bot transfer stations 140 (which may have extendable fingers for interfacing with slatted support shelves of the multilevel vertical conveyors which may be substantially similar to those described herein with respect to the bots 110).

0008The storage structure 130 may include multiple levels of storage rack modules where each level includes an array of storage spaces (arrayed on the multiple levels and in multiple rows on each level), picking aisles 130A formed between the rows of storage spaces, and transfer decks 130B. In alternate embodiments each level of the storage rack modules may also include respective bot transfer stations 140. The picking aisles 130A and transfer decks 130B being arranged for transferring case units between any of the storage areas of the storage structure 130 and any shelf of any multilevel vertical conveyor 150A, 150B for placing case units into picking stock and to retrieve the ordered case units. The bots 110 may be configured to place items, such as the above-described retail merchandise, into picking stock in the one or more levels of the storage structure 130 and then selectively retrieve ordered items for shipping the ordered items to, for example, a store or other suitable location. As may be realized, the storage and retrieval system may be configured to allow random accessibility to the storage spaces as will be described in greater detail below. For example, all storage spaces in the storage structure 130 may be treated substantially equally when determining which storage spaces are to be used when picking and placing case units from/to the storage structure 130 such that any storage space of sufficient size can be used to store case units. The storage structure 130 of the exemplary embodiments may also be arranged such that there is no vertical or horizontal array partitioning of the storage structure. For example, each multilevel vertical conveyor 150A, 150B may be common to all or substantially all storage spaces (e.g. the array of storage spaces) in the storage structure 130 such that any bot 110 can access each storage space and any multilevel vertical conveyor 150A, 150B can receive case units from any storage space on any level so that the multiple levels in the array of storage spaces substantially act as a single level (e.g. no vertical partitioning). Conversely case units from any shelf of each multilevel vertical conveyor 150A, 150B can be transferred to any or each storage space throughout the storage structure or to each storage space of any level of the storage structure. The multilevel vertical conveyors 150A, 150B can also receive case units from any storage space on any level of the storage structure 130 (e.g. no horizontal partitioning).

0009The storage structure 130 may also include charging stations 130C for replenishing, for example, a battery pack of the bots 110. In one exemplary embodiment, the charging stations 130C may be located at, for example, a transfer area 295 so that the bot can substantially simultaneously transfer case units between, for example, the bot and a multilevel vertical conveyor 150A, 150B while simultaneously being charged.

0010The bots 110 and other suitable features of the storage and retrieval system 100 may be controlled by, for example, one or more central system control computers (e.g. control server) 120 through, for example, any suitable network 180. The network 180 may be a wired network, a wireless network or a combination of a wireless and wired network using any suitable type and/or number of communication protocols. It is noted that, in one exemplary embodiment, the system control server 120 may be configured to manage and coordinate the overall operation of the storage and retrieval system 100 and interface with, for example, a warehouse management system, which in turn manages the warehouse facility as a whole.

0011As an exemplary operation of an order fulfillment process of the storage and retrieval system 100, case units for replenishing the picking stock are input at, for example, depalletizing workstations 210 (<figref idref="f0002">Fig. 2</figref>) so that case units bundled together on pallets (or other suitable container-like transport supports) are separated and individually carried on, for example, conveyors 240 (<figref idref="f0002">Fig. 2</figref>) or other suitable transfer mechanisms (e.g. manned or automated carts, etc.) to the in-feed transfer stations 170 (<figref idref="f0035">Fig. 29</figref>, Block 2200). The in-feed transfer stations 170 load the case units onto respective multilevel vertical conveyors 150A, which carry the case units to a predetermined level of the storage structure 130 (<figref idref="f0035">Fig. 29</figref>, Block 2210). Bots 110 located on the predetermined level of the storage structure 130 interface with the multilevel vertical conveyor 150A for removing the case units from the multilevel vertical conveyor 150A and transport the case units to predetermined storage areas within the storage structure 130. In alternate embodiments, the bots 110 assigned to the predetermined level interface with the bot transfer stations 140 for transferring the case units from the bot transfer stations 140 to a predetermined storage module of the storage structure 130. It is noted that each multilevel vertical conveyor 150A is capable of providing case units to any storage area within the storage structure 130. For example, a shelf 730 (<figref idref="f0008">Fig. 7A</figref>) of any one of the multilevel vertical conveyors 150A of the storage and retrieval system 100 may be moved to any one of the storage levels of the storage structure 130 (<figref idref="f0035">Fig. 29</figref>, Block 2220). Any bot 110 on a desired storage level may pick one or more case units (e.g. a pickface) from the shelf 730 of the multilevel vertical conveyor 150A (<figref idref="f0035">Fig. 29</figref>, Block 2230). The bot 110 may traverse the transfer deck 130B (<figref idref="f0001 f0002 f0003 f0004">Figs. 1-4</figref>) for accessing any one of the picking aisles 130A on a respective level of the storage structure 130 (<figref idref="f0035">Fig. 29</figref>, Block 2240). In a desired one of the picking aisles the bot can access any one of the storage areas of that picking aisle for placing the case units in any desired storage area regardless of the position of the storage area relative to the multilevel vertical conveyor 150A used to place the case units in the storage structure 130 (<figref idref="f0035">Fig. 29</figref>, Block 2250). Thus, any desired multilevel vertical conveyor 150A is capable of providing cases to a storage space located anywhere in the storage and retrieval system, regardless of the storage level or placement of the storage area on that level.

0012As may be realized, case units of the same type may be stored in different locations within the storage structure so that at least one of that type of item within the case unit may be retrieved when other ones of that type of item are inaccessible. The storage and retrieval system may also be configured to provide multiple access paths or routes to each storage location (e.g. pickface) so that bots may reach each storage location using, for example, a secondary path if a primary path to the storage location is obstructed. It is noted that the control server 120 and one or more sensors on the bots 110 may allow for the assignment and reservation of a pickface for putting away an inbound item such as during replenishment of the storage and retrieval system 100. In one exemplary embodiment, when a storage slot/place becomes available in the storage structure 130, the control server 120 may assign a fictitious item (e.g. an empty case) to the empty storage slot. If there are adjacent empty slots in the storage structure the empty cases of the adjacent storage slots may be combined to fill the empty space on the storage shelf. As may be realized, the size of the slots may be variable such as when dynamically allocating shelf space. For example, referring also to <figref idref="f0019">Figs. 15A-15C</figref>, instead of placing case units 5011 and 5012 in predetermined storage areas on the storage shelf 5001, the storage slots may be dynamically allocated such that the cases 5011, 5012 are replaced by three cases having the size of case unit 5010. For example, <figref idref="f0019">Fig. 15A</figref> illustrates a storage bay 5000 divided into storage slots S1-S4 as is done in conventional storage systems. The size of the storage slots S1-S4 may be a fixed size dependent on a size of the largest item (e.g. item 5011) to be stored on the shelf 600 of the storage bay 5000. As can be seen in <figref idref="f0019">Figure 15A</figref>, when case units 5010, 5012, 5013 of varying dimensions, which are smaller than item 5011, are placed in a respective storage slot S1, S2, S4 a significant portion of the storage bay capacity, as indicated by the shaded boxes, remains unused.

0013In accordance with an exemplary embodiment, <figref idref="f0019">Fig. 15B</figref> illustrates a storage bay 5001 having dimensions substantially similar to storage bay 5000. In <figref idref="f0019">Fig. 15B</figref> the case units 5010-5016 are placed on the shelf 600 using dynamic allocation such that the empty storage slots are substantially continuously resized as uncontained case units are placed on the storage shelves (e.g. the storage slots do not have a predetermined size and/or location on the storage shelves). As can be seen in <figref idref="f0019">Fig. 15B</figref>, dynamically allocating the storage space allows placement of case units 5014-5016 on shelf 600 in addition to case units 5010-5013 (which are the same case units placed in storage bay 5000 described above) such that the unused storage space, as indicated by the hatched boxed, is less than the unused storage space using the fixed sizes slots of <figref idref="f0019">Fig. 15A</figref>.

0014<figref idref="f0019">Fig. 15C</figref> illustrates a side by side comparison of the unused storage space for the fixed slots and dynamic allocation storage described above. It is noted that the unused storage space of bay 5001 using dynamic allocation may be decreased even further by decreasing the amount of space between the case units 5010-5016 which may allow for placement of additional case units on the shelf 600. As may be realized, as case units are placed within the storage structure the open storage spaces may be analyzed, by for example the control server 120, after each item placement and dynamically re-allocated according to a changed size of the open storage space so that additional case units having a size corresponding to (or less than) a size of the reallocated storage space may be placed in the re-allocated storage space. In alternate embodiments, the storage slots may also be allocated so that case units that are frequently picked together are located next to each other. When a predetermined pickface is reserved for an item that is being delivered, at least a portion of the empty case sitting in the location where the item is to be placed is replaced by a fictitious item having the features (e.g. size, etc.) of the item being delivered to prevent other inbound case units from being assigned to the predetermined pickface. If the item is smaller than the empty case that it is replacing, the empty case may be resized or replaced with a smaller empty case to fill the unused portion of the storage shelf. Another item may then be placed within the storage slot corresponding to the resized smaller empty case and so on.

0015When an order for case units is made any bots 110 on the storage level of the requested case units retrieves the corresponding case units (e.g. pickfaces) from a designated storage area of the storage structure 130 (<figref idref="f0036">Fig. 30</figref>, Block 2300). The bot 110 traverses the picking aisle 130A in which the case units were stored and the transfer aisle 130B for accessing any desired shelf 730 (<figref idref="f0008">Fig. 7B</figref>) of any one of the multilevel vertical conveyors 150B (<figref idref="f0036">Fig. 30</figref>, Block 2310). It is noted that the case units that comprise the order may be picked by the bots in any order. For example, a first bot 110 may traverse, for example, the transfer deck 130B for any suitable amount of time to, for example, allow other bots to pick respective case units of the order and deliver those case units to the multilevel vertical conveyor 150B if the case units of the other bots are to be delivered to the multilevel vertical conveyor before the case units of the first bot 110. As described herein, the case units may be delivered to the multilevel vertical conveyor at a predetermined time according to, for example, a predetermined sequence in a first sortation of the case units (<figref idref="f0036">Fig. 30</figref>, Block 2320). The bot 110 transfers the case units to the desired shelf of the multilevel vertical conveyor as described above (<figref idref="f0036">Fig. 30</figref>, Block 2330). In alternate embodiments, the bots may provide the case units to bot transfer stations 140 located on a level of the storage structure 130 from which the ordered case units were picked. The multilevel vertical conveyor 150B transports the ordered case units to the out-feed transfer stations 160 at a predetermined time according to, for example, a predetermined sequence in a second sortation of the case units (<figref idref="f0036">Fig. 30</figref>, Block 2340). It is noted that the multilevel vertical conveyors 150B are configured to allow the case units to continuously revolve around the conveyor loop so that the case units can be moved to, for example, an out-feed transfer station at any suitable time for fulfilling an order. For example, a first case unit is placed on a first shelf of the multilevel vertical conveyor 150B and a second case unit is placed on a second shelf of the multilevel vertical conveyor 150B where the first shelf is located in front of the second shelf in a sequence of shelves of the multilevel vertical conveyor 150B and the second case unit is to be provided to the out-feed transfer station 160 before the first case unit. The first shelf (holding the first case unit) may be allowed to pass the out-feed transfer station without unloading the first case unit to allow the second case unit to be removed from the second shelf. Thus, the case units may be placed on the shelves of the multilevel vertical conveyor 150B in any order. The out-feed transfer station 160 removes the case units from a desired shelf of the multilevel vertical conveyor at a desired time (<figref idref="f0036">Fig. 30</figref>, Block 2350) so that the individual case units are transported to palletizing workstations 220 (<figref idref="f0002">Fig. 2</figref>) by conveyors 230 (<figref idref="f0002">Fig. 2</figref>) where the individual case units are placed on outbound pallets (or other suitable container-like transport supports) in, for example, a predetermined sequence (as described above) to form mixed pallets 9002 (<figref idref="f0034">Fig. 28</figref>) for shipping to a customer. The out-feed transfer stations 160 and the palletizing workstations 220 may be referred to collectively as an order assembly station. Other examples, of material handling systems in which case units are transferred to an outbound container can be found in <patcit id="pcit0002" dnum="US92828904" dnum-type="L"><text>United States Patent Application No. 10/928,289 filed on August 28, 2004</text></patcit>, and <patcit id="pcit0003" dnum="US00230907" dnum-type="L"><text>United States Patent Application No. 12/002,309 filed on December 14, 2007</text></patcit>. As may be realized, the storage and retrieval system allows for ordering mixed case units of any suitable quantity without having to pick and transport, for example, entire trays, totes or pallets of case units to and from the storage structure 130.

0016Referring now to <figref idref="f0002 f0003 f0004">Figs. 2-4</figref>, exemplary configurations of the storage and retrieval system 100 are shown. As can be seen in <figref idref="f0002">Fig. 2</figref>, the storage and retrieval system 200 is configured as a single-ended picking structure in which only one side of the system 200 has a transfer section or deck 130B. The single-ended picking structure may be used in, for example, a building or other structure having loading docks disposed only on one side of the building. As can be seen in <figref idref="f0002">Fig. 2</figref>, the transfer deck 130B and picking aisles 130A allow bots 110 to traverse an entirety of a level of the storage structure 130 on which that bot 110 is located for transporting case units between any suitable storage locations/picking aisles 130A and any suitable multilevel vertical conveyors 150A, 150B. In this exemplary embodiment, the storage and retrieval system 200 includes a first and second storage section 230A, 230B located side by side so that the picking aisles of each section are substantially parallel with each other and facing the same direction (e.g. towards transfer deck 130B).

0017<figref idref="f0003">Fig. 3</figref> illustrates a storage and retrieval system 300 having a double sided picking structure for use in, for example, buildings or other structures having loading docks on two sides of the building. In <figref idref="f0003">Fig. 3</figref> the storage and retrieval system 300 includes two storage sections 340A, 340B that are arranged so that the picking aisles 130A in each of the storage sections 340A, 340B are parallel with each other but facing opposing directions such that substantially continuous picking aisles are formed between the opposing transfer decks 330A, 330B. As may be realized, an express travel lane 335 may be located between the opposing transfer decks 330A, 330B for allowing bots 110 to transit between the transfer decks 330A, 330B at greater speeds than those allowed within the picking aisles 130A. As may also be realized the bots 110 on each level of the picking structure of <figref idref="f0003">Fig. 3</figref> may traverse the entirety of its respective level such that the bot 110 may serve to transport case units throughout the two storage sections 340A, 340B and to and from respective input and output workstations.

0018<figref idref="f0004">Fig. 4</figref> illustrates a storage and retrieval system 400 substantially similar to storage and retrieval system 300. However, the storage and retrieval system 400 illustrates maintenance access gateways 410A, 410B, 410C for allowing, as an example, humans and/or service equipment to enter the storage and retrieval system for performing maintenance and/or repairs to the storage and retrieval system 400. As will be described in greater detail below, the storage and retrieval systems described herein may be configured with suitable features for disabling one or more bots 110, conveyors or any other suitable features of the storage and retrieval systems in one or more areas of the storage and retrieval system 100 when maintenance is being performed within the storage and retrieval system 100. In one example, the control server 120 may be configured to disable/enable features of the storage and retrieval system.

0019The storage and retrieval system, such as those described above with respect to <figref idref="f0002 f0003 f0004">Figs. 2-4</figref>, may be configured to allow substantially unimpeded access to substantially all areas of the storage and retrieval system in the event of, for example, a stoppage in the system so that the system continues operation with substantially no or minimized loss in throughput. A stoppage in the system may include, but is not limited to, a disabled bot 110 within a picking aisle or on a transfer deck, a disabled multilevel vertical conveyor 150A, 150B and/or a disabled in-feed or out-feed transfer station 160, 170. As may be realized, the storage and retrieval system 200, 300, 400 may be configured to allow substantially redundant access to each of the storage locations within the picking aisles. For example, a loss of an input multilevel vertical conveyor 150A may result in substantially no loss of storage space or throughput as there are multiple input multilevel vertical conveyors 150A that can transport case units to each level/storage space within the storage structure 130. As another example, the loss of a bot out of a picking aisle may result in substantially no loss of storage space or throughput as there are multiple bots 110 on each level capable of transferring case units between any one of the storage spaces and any one of the multilevel vertical conveyors 150A, 150B. In still another example, the loss of a bot 110 within a picking aisle may result in substantially no loss of storage space or throughput as only a portion of a picking aisle is blocked and the storage and retrieval system may be configured to provide multiple paths of travel to each of the storage spaces or types of case units within the storage spaces. In yet another example, a loss of an output multilevel vertical conveyor 150B may result in substantially no loss of storage space or throughput as there are multiple output multilevel vertical conveyors 150B that can transport case units from each level/storage space within the storage structure 130. In the exemplary embodiments, transport of the case units (e.g. via the multilevel vertical conveyors and bots) is substantially independent of storage capacity and case unit distribution and vice versa (e.g. the storage capacity and case unit distribution is substantially independent of transport of the case units) such that there is substantially no single point of failure in either storage capacity or throughput of case units through the storage and retrieval system.

0020The control server 120 may be configured to communicate with the bots 110, multilevel vertical conveyors 150A, 150B, in-feed or out-feed transfer stations 160, 170 and other suitable features/components of the storage and retrieval system in any suitable manner. The bots 110, multilevel vertical conveyors 150A, 150B and transfer stations 160, 170 may each have respective controllers that communicate with the control server 120 for conveying and/or receiving, for example, a respective operational status, location (in the case of the bots 110) or any other suitable information. The control server may record the information sent by the bots 110, multilevel vertical conveyors 150A, 150B and transfer stations 160, 170 for use in, for example, planning order fulfillment or replenishment tasks.

0021As may be realized, any suitable controller of the storage and retrieval system such as for example, control server 120, may be configured to create any suitable number of alternative pathways for retrieving one or more case units from their respective storage locations when a pathway providing access to those case units is restricted or otherwise blocked. For example, the control server 120 may include suitable programming, memory and other structure for analyzing the information sent by the bots 110, multilevel vertical conveyors 150A, 150B and transfer stations 160, 170 for planning a bot's 110 primary or preferred route to a predetermined item within the storage structure. The preferred route may be the fastest and/or most direct route that the bot 110 can take to retrieve the item. In alternate embodiments the preferred route may be any suitable route. The control server 120 may also be configured to analyze the information sent by the bots 110, multilevel vertical conveyor 150A, 150B and transfer stations 160, 170 for determining if there are any obstructions along the preferred route. If there are obstructions along the preferred route the control server 120 may determine one or more secondary or alternate routes for retrieving the item so that the obstruction is avoided and the item can be retrieved without any substantial delay in, for example, fulfilling an order. It should be realized that the bot route planning may also occur on the bot 110 itself by, for example, any suitable control system, such as control system 1220 (<figref idref="f0001">Figs. 1</figref> and <figref idref="f0017">13</figref>) onboard the bot 110. As an example, the bot control system 1220 may be configured to communicate with the control server 120 for accessing the information from other bots 110, the multilevel vertical conveyors 150A, 150B and the transfer stations 160, 170 for determining the preferred and/or alternate routes for accessing an item in a manner substantially similar to that described above. It is noted that the bot control system 1220 may include any suitable programming, memory and/or other structure to effect the determination of the preferred and/or alternate routes.

0022Referring to <figref idref="f0004">Fig. 4</figref>, as a non-limiting example, in an order fulfillment process the bot 110A, which is traversing transfer deck 330A, may be instructed to retrieve an item 499 from picking aisle 131. However, there may be a disabled bot 110B blocking aisle 131 such that the bot 110A cannot take a preferred (e.g. the most direct and/or fastest) path to the item 499. In this example, the control server may instruct the bot 110A to traverse an alternate route such as through any unreserved picking aisle (e.g. an aisle without a bot in it or an aisle that is otherwise unobstructed) so that the bot 110A can travel along, for example, transfer deck 330B. The bot 110A can enter the end of the picking aisle 131 opposite the blockage from transfer deck 330B so as to avoid the disabled bot 110B for accessing the item 499. In another exemplary embodiment, as can be seen in <figref idref="f0003">Fig. 3</figref>, the storage and retrieval system may include one or more bypass aisles 132 that run substantially transverse to the picking aisles to allow the bots 110 to move between picking aisles 130A in lieu of traversing the transfer decks 330A, 330B. The bypass aisles 132 may be substantially similar to travel lanes of the transfer decks 330A, 330B, as described herein, and may allow bidirectional or unidirectional travel of the bots through the bypass aisle. The bypass aisle 132 may provide one or more lanes of bot travel where each lane has a floor and suitable guides for guiding the bot along the bypass aisle in a manner similar to that described herein with respect to the transfer decks 330A, 330B. In alternate embodiments, the bypass aisles may have any suitable configuration for allowing the bots 110 to traverse between the picking aisles 130A. It is noted that while the bypass aisle 132 is shown with respect to a storage and retrieval system having transfer decks 330A, 330B disposed on opposite ends of the storage structure, in other exemplary embodiments, storage and retrieval systems having only one transfer deck, such as shown in <figref idref="f0002">Fig. 2</figref>, may also include one or more bypass aisles 132. As may also be realized, if one of the in-feed or out-feed transfer stations 160, 170 or multilevel vertical conveyors 150A, 150B become disabled order fulfillment or replenishment tasks may be directed, by for example, control server 120, to other ones of the in-feed and out-feed transfer stations 160, 170 and/or multilevel vertical conveyors 150A, 150B without substantial disruption of the storage and retrieval system.

0023The storage and retrieval systems shown in <figref idref="f0002 f0003 f0004">Figs. 2-4</figref> have exemplary configurations only and in alternate embodiments the storage and retrieval systems may have any suitable configuration and components for storing and retrieving case units as described herein. For example, in alternate embodiments the storage and retrieval system may have any suitable number of storage sections, any suitable number of transfer decks and corresponding input and output workstations. As an example, a storage and retrieval system in accordance with the exemplary embodiments may include transfer decks and corresponding input and output stations located on three or four sides of the storage sections for serving, for example, loading docks disposed on various sides of a building.

0024Referring also to <figref idref="f0005">Figs. 5</figref>, <figref idref="f0006">6A</figref> and <figref idref="f0007">6B</figref>, the storage structure 130 will be described in greater detail. In accordance with an exemplary embodiment, the storage structure 130 includes, for example, any suitable number of vertical supports 612 and any suitable number of horizontal supports 610, 611, 613. It is noted that the terms vertical and horizontal are used for exemplary purposes only and that the supports of the storage structure 130 may have any suitable spatial orientation. In this exemplary embodiment, the vertical supports 612 and horizontal supports 610, 611, 613 may form an array of storage modules 501, 502, 503 having storage bays 510, 511. The horizontal supports 610, 611, 613 may be configured to support the storage shelves 600 (described below) as well as the floors 130F for the aisle spaces 130A, which may include tracks for the bots 110. The horizontal supports 610, 611, 613 may be configured to minimize the number of splices between horizontal supports 610, 611, 613 and thus, the number of splices that, for example, tires of the bots 110 will encounter. For exemplary purposes only, the aisle floor 130F may be a solid floor constructed of plymetal panels having, for example, a wood core sandwiched between sheets of sheet metal. In alternate embodiments the floors 130F may have any suitable layered, laminated, solid or other construction and be constructed of any suitable material(s), including, but not limited to plastics, metals and composites. In yet other alternate embodiments the aisle floors 130F may be constructed of a honeycomb structure or other suitable lightweight yet substantially rigid structure. The aisle floors 130F may be coated or treated with wear resistant materials or include replaceable sheets or panels that may be replaced when worn. The tracks 1300 (<figref idref="f0013">Fig. 11B</figref>) for the bots 110 may be incorporated into or otherwise affixed to the aisle floors 130F for guiding the bots 110 in substantially straight lines or paths of travel while the bots 110 are traveling within the storage structure 130. The floors 130F may be attached to, for example, one or more of the vertical and horizontal supports (or any other suitable support structure) in any suitable manner such as with any suitable fasteners including, but not limited to bolts and welds. In one exemplary embodiment, as can be seen in, for example, <figref idref="f0014">Fig. 11C</figref>, the tracks 1300 may be fixed to one or more vertical supports of the storage structure in any suitable manner such that the bot straddles adjacent tracks 1300 for traversing a picking aisle. As can be seen in <figref idref="f0014">Fig. 11C</figref> one or more of the picking aisles may be substantially vertical unobstructed by floors (e.g. the picking aisles do not have floors). The absence of floors on each picking level may allow maintenance personnel to walk down the picking aisles where the height between each storage level would otherwise substantially prevent the maintenance personnel from traversing the picking aisles.

0025Each of the storage bays 510, 511 may hold the picking stock on storage shelves 600 that are separated by aisle spaces 130A. It is noted that in one exemplary embodiment the vertical supports 612 and/or horizontal supports 610, 611, 613 may be configured to allow for adjusting the height or elevation of the storage shelves and/or aisle floors 130F relative to, for example, each other and a floor of the facility in which the storage and retrieval system is located. In alternate embodiments the storage shelves and floors may be fixed in elevation. As can be seen in <figref idref="f0005">Fig. 5</figref>, storage module 501 is configured as an end module having, for example, about half the width of the other storage modules 502, 503. As an example, the end module 501 may have a wall located on one side and the aisle space 130A located on the opposite side. The depth DI of end module 501 may be such that access to the storage shelves 600 on module 501 is achieved by the aisle space 130A located on but one side of the storage module 501, whereas the storage shelves 600 of modules 502, 503 may be accessed by storage aisles 130A located on both sides of the modules 502, 503 allowing for, as an example, the storage modules 502, 503 having a depth substantially twice that of the depth DI of storage module 501.

0026The storage shelves 600 may include one or more support legs 620L1, 620L2 extending from, for example, the horizontal supports 610, 611, 613. The support legs 620L1, 620L2 may have any suitable configuration and may be part of, for example, a substantially U-shaped channel 620 such that the legs are connected to each other through channel portion 620B. The channel portion 620B may provide an attachment point between the channel 620 and one or more horizontal supports 610, 611, 613. In alternate embodiments, each support leg 620L1, 620L2 may be configured to individually mount to the horizontal supports 610, 611, 613. In this exemplary embodiment, each support leg 620L1, 620L2 includes a bent portion 620H1, 620H2 having a suitable surface area configured to support case units stored on the shelves 600. The bent portions 620H1, 620H2 may be configured to substantially prevent deformation of the case units stored on the shelves. In alternate embodiments the leg portions 620H1, 620H2 may have a suitable thickness or have any other suitable shape and/or configuration for supporting case units stored on the shelves. As can be seen in <figref idref="f0006">Figs. 6A</figref> and <figref idref="f0007">6B</figref>, the support legs 620L1, 620L2 or channels 620 may form a slatted or corrugated shelf structure where spaces 620S between, for example, the support legs 620L1, 620L2 allow for arms or fingers of the bots 110 to reach into the shelving for transferring case units to and from the shelves as will be described in greater detail below. It is noted that the support legs 620L1, 620L2 of the shelves 600 may be configured for storing case units, where adjacent case units are spaced any suitable distance from each other. For example, a pitch or spacing between the support legs 620L1, 620L2 in the direction of arrow 698 may be such that the case units are placed on the shelves 600 with a distance of about one pitch between the case units to, for example, minimize contact between case units as the case units are placed and removed from the shelves by the bots 110. For exemplary purposes only, case units located adjacent one another may be spaced apart, for example, in direction 698 a distance of about 2.54 cm. In alternate embodiments, the spacing between the case units on the shelves may be any suitable spacing. It is also noted that transfer of case units to and from the multilevel vertical conveyors 150A, 150B (whether the transfer is made directly or indirectly by the bot 110) may occur in a substantially similar manner to that described above with respect to storage shelves 600.

0027Referring again to <figref idref="f0002 f0003 f0004">Figs. 2-4</figref>, at the end of each aisle in the storage structure 130 there may be a transition bay 290 (<figref idref="f0002">Fig. 2</figref>) that allows the bots 110 to transition onto the transfer decks 130B. As described above, the transfer decks 130B may be located at one or more ends of the aisles 130A. In one example, the transition bay 290 may be configured to allow the bots 110 to transition from travel along a rail(s) within the aisles 130A to travel that is free from being constrained by rails within the transfer decks 130B and to merge with bot traffic on the transfer decks 130B. The transfer decks 130B may include a stacked or vertical array of, for example, substantially looped decks, where each level of the storage structure 130 includes one or more respective transfer decks 130. In alternate embodiments the transfer decks may have any suitable shape and configuration. The transfer decks 130B may be unidirectional decks (i.e. the bots 110 travel in a single predetermined direction around the transfer deck 130B) configured to connect all of the picking aisles 130A on a respective level to corresponding input and output multilevel vertical conveyors 150A, 150B on the respective level. In alternate embodiments, the transfer decks may be bidirectional for allowing the bots to travel in substantially opposite directions around the transfer decks. To allow the bots 110 to access the multilevel vertical conveyors 150A, 150B without obstructing the travel lanes of the transfer decks 130B, each transfer deck 130B may be configured with spurs or transfer areas 295 which may extend from the transfer decks 130B. In one exemplary embodiment the spurs 295 may include tracks substantially similar to tracks 1300 (<figref idref="f0013">Fig. 11B</figref>) for guiding the bots 110 to the multilevel vertical conveyors 150A, 150B or, in alternate embodiments, the bot transfer stations 140. In alternate embodiments, the bots may travel and be guided within the spurs 295 in a manner substantially similar to that described herein with respect to the transfer decks.

0028The travel lanes of the transfer decks 130B may be wider than the travel lanes within the aisles of the storage structure 130. For exemplary purposes only, travel lanes of the transfer decks 130B may be configured to allow the bots 110 to make different types of turns, as will be described in greater detail below, when, for example, transitioning onto or off of the transfer decks 130B. The floor 330F of the transfer decks may have any suitable construction configured to support the bots 110 as they traverse their respective transfer deck(s) 130B. For exemplary purposes only, the transfer deck floors 330F may be substantially similar to the aisle floors 130F described above. In alternate embodiments the transfer deck floors 330F may have any suitable configuration and/or construction. The transfer deck floors 330F may be supported by a lattice of frames and columns that may be connected to, for example, one or more of the vertical supports 612 and horizontal supports 610, 611, 613 in any suitable manner. For example, in one exemplary embodiment the transfer decks may include cantilevered arms that may be driven or otherwise inserted into corresponding slots, recesses or other openings in one or more of the vertical supports 612 and horizontal supports 610, 611, 613. In alternate embodiments the transfer deck floors 330F may be supported by a structure substantially similar to that described above with respect to <figref idref="f0005">Figs. 5</figref>, <figref idref="f0006">6A</figref> and <figref idref="f0007">6B</figref>. As may be realized, the pitch of the transfer deck floors 330F may be substantially similar to the pitch of the respective aisle floors 130F.

0029In one exemplary embodiment, the storage structure 130 may include personnel floors 280 (which may include the maintenance access gateways 410A-410C) associated with each level of the storage structure. The personnel floors may be located, for example, within or adjacent to the aisles of the storage structure and/or the transfer decks 130B. In alternate embodiments, the personnel floors 280 may be suitably located to provided reach in access to one side of the transfer decks 130B from within the storage structure where the other opposite side of the transfer decks 130B is accessed through work platforms/scaffolding adjacent the workstations 210, 220 and/or multilevel vertical conveyors. In one exemplary embodiment, the personnel floors 280 may run the full length of each aisle 130A or transfer deck 130B. In alternate embodiments the personnel floors 280 may have any suitable length. The personnel floors 280 may be vertically spaced from each other at predetermined intervals where the space between the personnel floors 280 provides a personnel work zone for resolving problems with, as non-limiting examples, the bots 110, case units stored in the storage structure 130 and the storage structure 130 itself. The personnel floors 280 may be configured to provide walking surfaces for, as an example, maintenance technicians or other personnel where the walking zones are distinct from travel lanes of the bots 110. Access to the personnel floors may be provided through the maintenance access gateways 410A-410C or any other suitable access point. Movable barriers or other suitable structures may be provided along the aisles 130A and transfer decks 130B to further separate unintentional interaction between, for example the bots 110 and personnel. In one exemplary embodiment, in normal operation the movable barriers may be in a stowed or retracted position to allow, for example, the bot 110 to pass and access the storage shelves 600. The movable barriers may be placed in an extended position when personnel are located in a predetermined zone or location of the storage structure 130 to block bot 110 access to the aisle(s) or portions of the transfer decks where personnel are located. In one exemplary operation of storage structure maintenance for a predetermined zone of the storage structure 130, all active bots 110 may be removed from the predetermined zone. Bots 110 that require maintenance may be disabled and de-energized within the predetermined zone. The movable barriers may be extended to prevent active bots 110 from entering the predetermined zone and any locks preventing access to the personnel floors may be unlocked or removed. The extension and retraction of the movable barriers, disabling of the bots 110 and removal of bots 110 from the predetermined zone may be controlled in any suitable manner such as by, for example, any suitable control system such as a central controller server 120 and mechanical and/or electromechanical interlocks. It is noted that in alternate embodiments, the storage and retrieval system may include any suitable personnel access not limited to that described above.

0030The structure, such as structure 130, of the storage and retrieval systems described herein may be configured to sustain predetermined loads placed on the structure by normal service and events such as, for exemplary purposes only, earthquakes as defined by local and federal codes. As an example, these loads may include the dead weight of the structure, inventory stored in and transferred throughout the structure, the bots 110, seismic loads, thermal expansion and sufficient stiffness for bot control and positioning. The structure of the storage and retrieval systems 100 may also be configured for ease of assembly, maintenance access, modularity and efficient and economical material use. Non-limiting examples, of the codes to which the structure may be configured to comply include ASCE7, AISC Manual of Steel Construction, AISC Code of Standard Practice for Steel Buildings and Bridges, RMI (Rack Manufacturers Institute) and Materials Handling Industry of America. The structural components (e.g. vertical/horizontal supports, floors, etc.) of the storage and retrieval systems described herein may also include wear and/or corrosion resistant coatings including surface treatments such as, for example, paints and galvanization. In one example, the coating may include a base coat and a contrasting top coat such that any wearing of the top coat will be readily visible. In alternate embodiments the coatings and surface treatments may have any suitable configurations and colors so that wear is easily identifiable.

0031The storage structure 130 may be configured to be rapidly assembled and installed in the field in a "bottom up construction" (e.g. each level is constructed sequentially such that lower levels in the sequence are substantially completed before the upper levels in the sequence). For example, the vertical supports 612 and/or horizontal supports 610, 611, 613 (and/or any other components of the storage structure 130) may be predrilled, punched or otherwise preformed with assembly holes. Base plates for supporting each of the vertical supports 612 and for securing the vertical supports 612 to a floor may be preinstalled on the respective vertical supports 612. Templates may be provided for locating anchor bolts in the floor for securing the base plates. The vertical supports 612 may be configured with brackets for receiving and at least partially securing the horizontal supports 610, 611, 613. Preformed holes in the horizontal supports may also be used to, for example, bolt or otherwise fasten the horizontal supports to the vertical supports. The shelves 600 may be field assembled from prefinished components and affixed to, for example, the horizontal supports 610, 611, 613 in any suitable manner. Separate braces such as ties may be also provided for securing the horizontal supports 610, 611, 613. The transfer decks 130B may be installed in a manner substantially similar to that described above. The floors and decking of the storage structure 130 may be affixed to the horizontal supports in any suitable manner, such as for example through fasteners. The floors and decking may be preformed with installation holes to allow for securing the floors and decking to the horizontal supports. The tracking 1300 (<figref idref="f0013">Fig. 11B</figref>) for the bots 110 may be preinstalled on or within the aisle flooring or installed in the field using for example, preformed holes or other installation guides such as templates. It is noted that in alternate embodiments, the storage structure 130 may be constructed and assembled in any suitable manner.

0032Referring now to <figref idref="f0010 f0011">Figs. 9A-9D</figref>, the multilevel vertical conveyors 150A transfer pickfaces 750-753 from, for example, the in-feed transfer stations 170 (or any other suitable device or loading system) directly to, for example, the bots 110. In alternate embodiments the multilevel vertical conveyors 150A transfer pickfaces 750-753 from, for example, the in-feed transfer stations 170 indirectly to the bots 110 through the bot transfer stations 140 associated with each of the levels in the storage structure 130. As may be realized, the bot transfer stations 140 are disposed on respective levels of the storage structure adjacent the path of travel of the shelves 730 of a respective multilevel vertical conveyor 150A. In one exemplary embodiment, there may be a bot transfer station 140 corresponding to each of the positions A-D on the shelves 730. For example, a first bot transfer station 140 may remove load 750 from position A on shelf 730 while another bot transfer station 140 may remove load 752 from position C on shelf 730 and so on. In other exemplary embodiments, one bot transfer station 140 may serve to remove or place case units in more than one position A-D on the shelves 730. For example, one bot transfer station 140 may be configured for removing loads 750, 752 from positions A, C on the first side of the shelf 730 while another bot transfer station 140 may be configured to remove loads 751, 753 from positions B, D on the second side 1051 of the shelf. In alternate embodiments the bot transfer stations 140 may have any suitable configuration for accessing any suitable number of positions A-D of the shelves 730.

0033In an alternate embodiments, each bot transfer station 140 may include a frame 1100, one or more drive motors 1110 and a carriage system 1130. The frame 1100 may have any suitable configuration for coupling the bot transfer station 140 to, for example, any suitable supporting feature of the storage structure 130, such as one or more of the horizontal supports 610, 611 and vertical supports 612 (<figref idref="f0005">Fig. 5</figref>). The carriage system 1130 may be movably mounted to the frame 1100 through, for example, rails 1120 that are configured to allow the carriage system 1130 to move between retracted and extended positions as shown in <figref idref="f0010">Figs. 9A and 9B</figref>. The carriage system 1130 may include a carriage base 1132 and fingers 1135. The fingers 1135 may be mounted to the carriage base 1132 in a spaced apart arrangement so that the fingers 1135 extend from the carriage base 1132 in a cantilevered fashion. It is noted that each finger 1135 may be removably mounted to the carriage base 1132 for facilitating replacement or repair of individual fingers 1135. In alternate embodiments the fingers and carriage base may be of unitary one-piece construction. The fingers 1135 of the bot transfer stations 140 may be configured to pass between the fingers 910 (<figref idref="f0009">Fig.8</figref>) of the shelves 730 of the multilevel vertical conveyors 150A for removing loads such as load 1150 (which may be substantially similar to loads 750-753) from the shelves 730. The bot transfer station 140 may also include a load 1150 positioning device 1140 that retractably extends between, for example, the spaced apart fingers 1135 for effecting positioning of the load 1150 in a predetermined orientation relative to the bot transfer station 140. In still other alternate embodiments the carriage system 1130 may have any suitable configuration and/or components. The one or more drive motors 1110 may be any suitable motors mounted to the frame 1100 for causing the extension/retraction of the carriage system 1130 and the extension/retraction of the positioning device 1140 in any suitable manner such as by, for exemplary purposes only, drive belts or chains. In alternate embodiments, the carriage system and positioning device may be extended and retracted in any suitable manner.

0034Referring to <figref idref="f0012">Figs. 10</figref>, <figref idref="f0013 f0014">11A-11C</figref>, <figref idref="f0015">12A</figref> and <figref idref="f0016">12B</figref>, the bots 110 that transfer loads between, for example, the bot transfer stations and the storage shelves will be described in greater detail. It is noted that in one exemplary embodiment the bots 110 may transfer loads directly to and/or from the multilevel vertical conveyors 150A, 150B as will be described below. It is noted that in one exemplary embodiment the bots 110 may transfer loads directly to and/or from the multilevel vertical conveyors 150A, 150B in a manner substantially similar to that described with respect to the bot transfer stations 140. In one example, the bots 110 may be configured for substantially continuous operation. For exemplary purposes only, the bots 110 may have a duty cycle of about ninety-five (95) percent. In alternate embodiments the bots may have any suitable duty cycle and operation periods.

0035As can be seen in <figref idref="f0012">Fig. 10</figref>, the bots 110 generally include a frame 1200, a drive system 1210, a control system 1220, and a payload area 1230. The drive system 1210 and control system 1220 may be mounted to the frame in any suitable manner. The frame may form the payload area 1230 and be configured for movably mounting a transfer arm or effector 1235 to the bot 110.

0036In one exemplary embodiment, the drive system 1210 may include two drive wheels 1211, 1212 disposed at a drive end 1298 of the bot 110 and two idler wheels 1213, 1214 disposed at a driven end 1299 of the bot 110. The wheels 1211-1214 may be mounted to the frame 1200 in any suitable manner and be constructed of any suitable material, such as for example, low-rolling-resistance polyurethane. In alternate embodiments the bot 110 may have any suitable number of drive and idler wheels. In one exemplary embodiment, the wheels 1211-1214 may be substantially fixed relative to the a longitudinal axis 1470 (<figref idref="f0015">Fig. 12A</figref>) of the bot 110 (e.g. the rotational plane of the wheels is fixed in a substantially parallel orientation relative to the longitudinal axis 1470 of the bot) to allow the bot to move in substantially straight lines such as when, for example, the bot is travelling on a transfer deck 130B (<figref idref="f0002">Fig. 2</figref>) or within a picking aisle 130A (<figref idref="f0002">Fig. 2</figref>). In alternate embodiments, the rotational plane of one or more of the drive wheels and idler wheels may be pivotal (e.g. steerable) relative to the longitudinal axis 1470 of the bot for providing steering capabilities to the bot 110 by turning the rotational planes of one or more of the idler or drive wheels relative to the longitudinal axis 1470. The wheels 1211-1214 may be substantially rigidly mounted to the frame 1200 such that the axis of rotation of each wheel is substantially stationary relative to the frame 1200. In alternate embodiments the wheels 1211-1214 may be movably mounted to the frame by, for example, any suitable suspension device, such that the axis of rotation of the wheels 1211-1214 is movable relative to the frame 1200. Movably mounting the wheels 1211-1214 to the frame 1200 may allow the bot 110 to substantially level itself on uneven surfaces while keeping the wheels 1211-1214 in contact with the surface.

0037Each of the drive wheels 1211, 1212 may be individually driven by a respective motor 1211M, 1212M. The drive motors 1211M, 1212M may be any suitable motors such as, for exemplary purposes only, direct current electric motors. The motors 1211M, 1212M may be powered by any suitable power source such as by, for example, a capacitor 1400 (<figref idref="f0015">Fig. 12A</figref>) mounted to the frame 1200. In alternate embodiments the power source may be any suitable power source such as, for example, a battery or fuel cell. In still other alternate embodiments the motors may be alternating current electric motors or internal combustion motors. In yet another alternate embodiment, the motors may be a single motor with dual independently operable drive trains/transmissions for independently driving each drive wheel. The drive motors 1211M, 1212M may be configured for bi-directional operation and may be individually operable under, for example, control of the control system 1220 for effecting steering of the bot 110 as will be described below. The motors 1211M, 1212M may be configured for driving the bot 110 at any suitable speed with any suitable acceleration when the bot is in either a forward orientation (e.g. drive end 1299 trailing the direction of travel) or a reverse orientation (e.g. drive end 1298 leading the direction of travel). In this exemplary embodiment, the motors 1211M, 1212M are configured for direct driving of their respective drive wheel 1211, 1212. In alternate embodiments, the motors 1211M, 1212M may be indirectly coupled to their respective wheels 1211, 1212 through any suitable transmission such as, for example, a drive shaft, belts and pulleys and/or a gearbox. The drive system 1210 of the bot 110 may include an electrical braking system such as for example, a regenerative braking system (e.g. to charge the capacitor 1400 under braking). In alternate embodiments, the bot 110 may include any suitable mechanical braking system. The drive motors may be configured to provide any suitable acceleration/deceleration rates and any suitable bot travel speeds. For exemplary purposes only the motors 1211M, 1212M may be configured to provide the bot (while the bot is loaded at full capacity) a rate of acceleration/deceleration of about 3.048 m/sec², a transfer deck 130B cornering speed of about 1.524 m/sec and a transfer deck straightaway speed of about 9.144 m/sec.

0038As noted above drive wheels 1211, 1212 and idler wheels 1213, 1214 are substantially fixed relative to the frame 1200 for guiding the bot 110 along substantially straight paths while the bot is travelling on, for example, the transfer decks 130B, 330A, 330B (e.g. <figref idref="f0002">Figs. 2</figref>, <figref idref="f0003">3</figref> and <figref idref="f0004">4</figref>). Corrections in the straight line paths may be made through differential rotation of the drive wheels 1211, 1212 as described herein. In alternate embodiments, guide rollers 1250, 1251 mounted to the frame may also aid in guiding the bot 110 on the transfer deck 130B such as through contact with a wall 1801, 2100 (<figref idref="f0018">Fig. 14</figref>) of the transfer deck 130. However, in this exemplary embodiment the fixed drive and idler wheels 1211-1214 may not provide agile steering of the bot such as when, for example, the bot 110 is transitioning between the picking aisles 130A, transfer decks 130B or bot transfer areas 295. In one exemplary embodiment, the bot 110 may be provided with one or more retractable casters 1260, 1261 for allowing the bot 110 to make, for example, substantially right angle turns when transitioning between the picking aisles 130A, transfer decks 130B and bot transfer areas 295. It is noted that while two casters 1260, 1261 are shown and described, in alternate embodiments the bot 110 may have more or less than two retractable casters. The retractable casters 1260, 1261 may be mounted to the frame 1200 in any suitable manner such that when the casters 1260, 1261 are in a retracted position the idler wheels 1213, 1214 are in contact with a flooring surface, such as surface 1300S of the rails 1300 or a transfer deck 130B of the storage structure 130. As the casters 1260, 1261 are extended or lowered the idler wheels 1213, 1214 are lifted off of the flooring surface so that the driven end 1299 of the bot 110 can be pivoted about a point P (<figref idref="f0015">Fig. 12A</figref>) of the bot. For example, the motors 1211M, 1212M may be individually and differentially operated for causing the bot 110 to pivot about point P which is located, for example, midway between the wheels 1211, 1212 while the driven end 1299 of the bot swings about point P accordingly via the casters 1260, 1261.

0039In other exemplary embodiments, the idler wheels 12313, 1214 may be replaced by non-retractable casters 1260', 1261' (<figref idref="f0016">Fig. 12B</figref>) where the straight line motion of the bot 110 is controlled by differing rotational speeds of each of the drive wheels 1211, 1212 as described herein. The non-retractable casters 1260', 1261' may be releasably lockable casters such that casters 1260', 1261' may be selectively locked in predetermined rotational orientations to, for example, assist in guiding the bot 110 along a travel path. For example, during straight line motion of the bot 110 on the transfer deck 130B or within the picking aisles 130A the non-retractable casters 1260', 1261' may be locked in an orientation such that the wheels of the casters 1260', 1261' are substantially in-line with a respective one of the drive wheels 1213, 1214 (e.g. the rotational plane of the wheels of the casters is fixed in a substantially parallel orientation relative to the longitudinal axis 1470 of the bot). The rotational plane of the wheels of the non-retractable casters 1260', 1261' may be locked and released relative to the longitudinal axis 1470 of the bot 110 in any suitable manner. For example, a controller of the bot 110 may be configured to effect the locking and releasing of the casters 1260', 1261' by for example, controlling any suitable actuator and/or locking mechanism. In alternate embodiments any other suitable controller disposed on or remotely from the bot 110 may be configured to effect the locking and releasing of the casters 1260', 1261'.

0040The bot 110 may also be provided with guide wheels 1250-1253. As can be best seen in <figref idref="f0013">Fig. 11B</figref>, while the bot 110 is travelling in, for example, the picking aisles 130A and/or transfer areas 295 the movement of the bot 110 may be guided by a tracked or rail guidance system. The rail guidance system may include rails 1300 disposed on either side of the bot 110. The rails 1300 and guide wheels 1250-1253 may allow for high-speed travel of the bot 110 without complex steering and navigation control subsystems. The rails 1300 may be configured with a recessed portion 1300R shaped to receive the guide wheels 1250-1253 of the bot 110. In alternate embodiments the rails may have any suitable configuration such as, for example, without recessed portion 1300R. The rails 1300 may be integrally formed with or otherwise fixed to, for example, one or more of the horizontal and vertical supports 398, 399 of the storage rack structure 130. As can be seen in <figref idref="f0014">Fig. 11C</figref> the picking aisles may be substantially floor-less such that bot wheel supports 1300S of the guide rails 1300 extend away from the storage areas a predetermined distance to allow a sufficient surface area for the wheels 1211-1214 (or in the case of lockable casters, wheels 1260', 1261') of the bot 110 to ride along the rails 1300. In alternate embodiments the picking aisles may have any suitable floor that extends between adjacent storage areas on either side of the picking aisle. In one exemplary embodiment, the rails 1300 may include a friction member 1300F for providing traction to the drive wheels 1211, 1212 of the bot 110. The friction member 1300F may be any suitable member such as for example, a coating, an adhesive backed strip, or any other suitable member that substantially creates a friction surface for interacting with the wheels of the bot 110.

0041While four guide wheels 1250-1253 are shown and described it should be understood that in alternate embodiments the bot 110 may have any suitable number of guide wheels. The guide wheels 1250-1253 may be mounted to, for example, the frame 1200 of the bot in any suitable manner. In one exemplary embodiment, the guide wheels 1250-1253 may be mounted to the frame 1200, through for example, spring and damper devices so as to provide relative movement between the guide wheels 1250-1253 and the frame 1200. The relative movement between the guide wheels 1250-1253 and the frame may be a dampening movement configured to, for example, cushion the bot 110 and its payload against any change in direction or irregularities (e.g. misaligned joints between track segments, etc.) in the track 1300. In alternate embodiments, the guide wheels 1250-1253 may be rigidly mounted to the frame 1200. The fitment between the guide wheels 1250-1253 and the recessed portion 1300R of the track 1300 may be configured to provide stability (e.g. anti-tipping) to the bot during, for example, cornering and/or extension of the transfer arm 1235 (e.g. to counteract any tipping moments created by a cantilevered load on the transfer arm). In alternate embodiments, the bot may be stabilized in any suitable manner during cornering and/or extension of the transfer arm 1235. For example, the bot 110 may include a suitable counterweight system for counteracting any moment that is created on the bot 110 through the extension of the transfer arm 1235.

0042The transfer arm 1235 may be movably mounted to the frame 1200 within, for example, the payload area 1230. It is noted that the payload area 1230 and transfer arm 1235 may be suitably sized for transporting cases in the storage and retrieval system 100. For example, the width W of the payload area 1230 and transfer arm 1235 may be substantially the same as or larger than a depth D (<figref idref="f0007">Fig. 6B</figref>) of the storage shelves 600. In another example, the length L of the payload area 1230 and transfer arm 1235 may be substantially the same as or larger than the largest item length transferred through the system 100 with the item length being oriented along the longitudinal axis 1470 of the bot 110.

0043Referring now to <figref idref="f0017">Fig. 13</figref>, the control system 1220 of the bot will be described. The control system 1220 may be configured to provide communications, supervisory control, bot localization, bot navigation and motion control, case sensing, case transfer and bot power management. In alternate embodiments the control system 1220 may be configured to provide any suitable services to the bot 110. The control system 1220 may include any suitable programs or firmware configured for performing the bot operations described herein. The control system 1220 may be configured to allow for remote (e.g. over a network) debugging of the bot. In one example, the firmware of the bot may support a firmware version number that can be communicated over, for example, the network 180 so the firmware may be suitably updated. The control system 1220 may allow for assigning a unique bot identification number to a respective bot 110 where the identification number is communicated over the network 180 to, for example, track a status, position or any other suitable information pertaining to the bot 110. In one example, the bot identification number may be stored in a location of the control system 1220 such that the bot identification number is persistent across a power failure but is also changeable.

0044In one exemplary embodiment, the control system 1220 may be divided into a front and back end having any suitable subsystems 1702, 1705. The control system 1220 may include an on-board computer 1701 having, for example, a processor, volatile and non-volatile memory, communication ports and hardware interface ports for communicating with the on-board control subsystems 1702, 1705. The subsystems may include a motion control subsystem 1705 and an input/output subsystem 1702. In alternate embodiments, the bot control system 1220 may include any suitable number of portions/subsystems.

0045The front end 1220F may be configured for any suitable communications (e.g. synchronous or asynchronous communications regarding bot commands, status reports, etc.) with the control server 120. The communications between the bot 110 and the control server 120 may, in one exemplary embodiment, provide for a substantially automatic bootstrap from, for example, initial installation of the bot 110, operational failure of the bot 110 and/or bot replacement. For example, when a bot 110 is initialized, the bot may obtain an identification number and subscribe to a bot proxy 2680 (Fig. 27A) via communication with the front end 1220F. This allows the bot to become available for receiving tasks. The front end 1220F may receive and decompose tasks assigned to the bot 110 and reduce the task into primitives (e.g. individual commands) that the back end 1220B can understand. In one example, the front end 1220F may consult any suitable resources such as, for example, a map of the storage structure 130 to decompose a task into the primitives and to determine the various movement related parameters (e.g. velocity, acceleration, deceleration, etc.) for each portion of the task. The front end 1220F may pass the primitives and movement related parameters to the back end 1220B for execution by the bot 110. The bot front end 1220F may be configured as a pair of state machines where a first one of the state machines handles communication between the front end 1220F and the control server 120 and a second one of the state machines handles communication between the front end 1220F and the back end 1220B. In alternate embodiments the front end 1220F may have any suitable configuration. The first and second state machines may interact with each other by generating events for each other. The state machines may include a timer for handling timeouts such as during, transfer deck 130B access. In one example, when a bot 110 is entering a transfer deck 130B, the bot proxy 2680 may inform the front end 1220F of a predetermined entrance time that the bot is to enter the transfer deck 130B. The front end 1220F may start the timer of the state machines according to a time the bot is to wait (based on the predetermined entrance time) before entering the deck. It is noted that the timers (e.g. clocks) of the state machines and the bot proxy 2680 may be synchronized clocks so as to substantially avoid collisions between bots travelling on the transfer deck 130B and bots entering the transfer deck 130B.

0046The back end 1220B may be configured to effect the functions of the bot described above (e.g. lowering the casters, extending the fingers, driving the motors, etc.) based on, for example, the primitives received from the front end 1220F. In one example, the back end 122B may monitor and update bot parameters including, but not limited to, bot position and velocity and send those parameters to the bot front end 122OF. The front end 1220F may use the parameters (and/or any other suitable information) to track the bot's 110 movements and determine the progress of the bot task(s). The front end 1220F may send updates to, for example, the bot proxy 2680 so that the control server 120 can track the bot movements and task progress and/or any other suitable bot activities.

0047The motion control subsystem 1705 may be part of the back end 1220B and configured to effect operation of, for example, the drive motors 1211M, 1212M, 1235L, 1495, 1490, 1610 of the bot 110 as described herein. The motion control subsystem 1705 may be operatively connected to the computer 1701 for receiving control instructions for the operation of, for example, servo drives (or any other suitable motor controller) resident in the motion control subsystem 1705 and subsequently their respective drive motors 1211M, 1212M, 1235L, 1495, 1490, 1610. The motion control subsystem 1705 may also include suitable feedback devices, such as for example, encoders, for gathering information pertaining to the drive motor operation for monitoring, for example, movement the transfer arm 1235 and its components (e.g. when the fingers 1235A are latched to the pusher bar, a location of the pusher bar, extension of the fence, etc.) or the bot 110 itself. For example, an encoder for the drive motors 1211M, 1212M may provide wheel odometry information, and encoders for lift motor 1235L and extension motor 1495 may provide information pertaining to a height of the transfer arm 1235 and a distance of extension of the fingers 1235A. The motion control subsystem 1705 may be configured to communicate the drive motor information to the computer 1701 for any suitable purpose including but not limited to adjusting a power level provided to a motor.

0048The input/output subsystem 1702 may also be part of the back end 1220B and configured to provide an interface between the computer 1701 and one or more sensors 1710-1716 of the bot 110. The sensors may be configured to provide the bot with, for example, awareness of its environment and external objects, as well as the monitor and control of internal subsystems. For example, the sensors may provide guidance information, payload information or any other suitable information for use in operation of the bot 110. For exemplary purposes only, the sensors may include a bar code scanner 1710, slat sensors 1711, lines sensors 1712, case overhang sensors 1713, arm proximity sensors 1714, laser sensors 1715 and ultrasonic sensors 1716.

0049The bar code scanner (s) 1710 may be mounted on the bot 110 in any suitable location. The bar code scanners(s) 1710 may be configured to provide an absolute location of the bot 110 within the storage structure 130. The bar code scanner(s) 1710 may be configured to verify aisles references and locations on the transfer decks by, for example, reading bar codes located on, for example the transfer decks, picking aisles and transfer station floors to verify a location of the bot 110. The bar code scanner(s) 1710 may also be configured to read bar codes located on case units stored in the shelves 600.

0050The slat sensors 1711 may be mounted to the bot 110 at any suitable location. The slat sensors 1711 may be configured to count the slats or legs 620L1, 620L2 of the storage shelves 600 (<figref idref="f0007">Fig. 6B</figref>) for determining a location of the bot 110 with respect to the shelving of, for example, the picking aisles 130A. The slat information may be used by the computer 1701 to, for example, correct the bot's odometry and allow the bot 110 to stop with its fingers 1235A positioned for insertion into the spaces between the legs 620L1, 620L2. In one exemplary embodiment, the bot may include slat sensors 1711 on the drive end 1298 and the driven end 1299 of the bot to allow for slat counting regardless of which end of the bot is facing the direction the bot is travelling. The slat sensors 1711 may be any suitable sensors such as, for example, close range triangulation or "background suppression" sensors. The slat sensors 1711 may be oriented on the bot 110 so that the sensors see down into the slats and ignore, for example, the thin edges of the legs 620L1, 620L2. For exemplary purposes only, in one exemplary embodiment the slat sensors 1711 may be mounted at about a 15 degree angle from perpendicular (relative to the longitudinal axis 1470 (<figref idref="f0015">Fig. 12A</figref>) of the bot 110). In alternate embodiments the slat sensors 1711 may be mounted on the bot in any suitable manner.

0051The line sensors 1712 may be any suitable sensors mounted to the bot in any suitable location, such as for exemplary purposes only, on bumpers 1273 (<figref idref="f0012">Fig. 10</figref>) disposed on the drive and driven ends of the bot 110. For exemplary purposes only, the line sensors may be diffuse infrared sensors. The line sensors 1712 may be configured to detect guidance lines provided on, for example, the floor of the transfer decks 130B as will be described in greater detail below. The bot 110 may be configured to follow the guidance lines when travelling on the transfer decks 130B and defining ends of turns when the bot is transitioning on or off the transfer decks 130B. The line sensors 1712 may also allow the bot 110 to detect index references for determining absolute localization where the index references are generated by crossed guidance lines. In this exemplary embodiment the bot 110 may have about six line sensors 1712 but in alternate embodiments the bot 110 may have any suitable number of line sensors.

0052The case overhang sensors 1713 may be any suitable sensors that are positioned on the bot to span the payload area 1230 adjacent the top surface of the fingers 1235A. The case overhang sensors 1713 may be disposed at the edge of the payload area 1230 to detect any loads that are at least partially extending outside of the payload area 1230. In one exemplary embodiment, the case overhang sensors 1713 may provide a signal to the computer 1701 (when there is no load or other case units obstructing the sensor) indicating that the fence 1235F may be raised for securing the load(s) within the payload area 1230. In other exemplary embodiments, the case overhang sensors 1713 may also confirm a retraction of the fence 1235F before, for example, the fingers 1235A are extended and/or a height of the transfer arm 1235 is changed.

0053The arm proximity sensors 1714 may be mounted to the bot 110 in any suitable location, such as for example, on the transfer arm 1235. The arm proximity sensors 1714 may be configured to sense objects around the transfer arm 1235 and/or fingers 1235A of the transfer arm 1235 as the transfer arm 1235 is raised/lowered and/or as the fingers 1235A are extended/retracted. Sensing objects around the transfer arm 1235 may, for exemplary purposes only, substantially prevent collisions between the transfer arm 1235 and objects located on, for example, shelves 600 or the horizontal and/or vertical supports of the storage structure 130.

0054The laser sensors 1715 and ultrasonic sensors 1716 (collectively referred to as case sensors) may be configured to allow the bot 110 to locate itself relative to each item forming the load carried by the bot 110 before the case units are picked from, for example, the storage shelves 600 and/or bot transfer station (or any other location suitable for retrieving payload). The case sensors may also allow the bot to locate itself relative to empty storage location for placing case units in those empty storage locations. This location of the bot relative to the case units to be picked and/or empty storage locations for placing an item may be referred to as bot localization, which will be described in greater detail below. The case sensors may also allow the bot 110 to confirm that a storage slot (or other load depositing location) is empty before the payload carried by the bot is deposited in, for example, the storage slot. In one example, the laser sensor 1715 may be mounted to the bot at a suitable location for detecting edges of case units to be transferred to (or from) the bot 110. The laser sensor 1715 may work in conjunction with, for example, retro-reflective tape (or other suitable reflective surface, coating or material) located at, for example, the back of the shelves 600 to enable the sensor to "see" all the way to the back of the storage shelves 600. The reflective tape located at the back of the storage shelves allows the laser sensor 1715 to be substantially unaffected by the color, reflectiveness, roundness or other suitable characteristics of the case units located on the shelves 600. The ultrasonic sensor 1716 may be configured to measure a distance from the bot 110 to the first item in a predetermined storage area of the shelves 600 to allow the bot 110 to determine the picking depth (e.g. the distance the fingers 1235A travel into the shelves 600 for picking the item(s) off of the shelves 600). One or more of the case sensors may allow for detection of case orientation (e.g. skewing of cases within the storage shelves 600) by, for example, measuring the distance between the bot 110 and a front surface of the case units to be picked as the bot 110 comes to a stop adjacent the case units to be picked. The case sensors may allow verification of placement of an item on, for example, a storage shelf 600 by, for example, scanning the item after it is placed on the shelf.

0055It is noted that the computer 1701 and its subsystems 1702, 1705 may be connected to a power bus for obtaining power from, for example, the capacitor 1400 through any suitable power supply controller 1706. It is noted that the computer 1701 may be configured to monitor the voltage of the capacitor 1400 to determine its state of charge (e.g. its energy content). In one exemplary embodiment, the capacitor may be charged through charging stations located at, for example, one or more transfer areas 295 or at any other suitable location of the storage structure 130 so that the bot is recharged when transferring payloads and remains in substantially continuous use. The charging stations may be configured to charge the capacitor 1400 within the time it takes to transfer the payload of the bot 110. For exemplary purposes only, charging of the capacitor 1400 may take about fifteen (15) seconds. In alternate embodiments, charging the capacitor may take more or less than about fifteen (15) seconds. During charging of the capacitor 1400 the voltage measurement may be used by the computer 1701 to determine when the capacitor is full and to terminate the charging process. The computer 1701 may be configured to monitor a temperature of the capacitor 1400 for detecting fault conditions of the capacitor 1400.

0056The computer 1701 may also be connected to a safety module 1707 which includes, for example, an emergency stop device 1311 (<figref idref="f0013">Fig. 11A</figref>) which when activated effects a disconnection of power to, for example, the motion control subsystem 1705 (or any other suitable subsystem(s) of the bot) for immobilizing or otherwise disabling the bot 110. It is noted that the computer 1701 may remain powered during and after activation of the emergency stop device 1311. The safety module 1707 may also be configured to monitor the servo drives of the motion control subsystem 1705 such that when a loss of communication between the computer and one or more of the servo drives is detected, the safety module 1707 causes the bot to be immobilized in any suitable manner. For example, upon detection of a loss of communication between the computer 1701 and one or more servo drives the safety module 1707 may set the velocity of the drives motors 1211M, 1212M to zero for stopping movement of the bot 110.

0057The communication ports of the control system 1220 may be configured for any suitable communications devices such as, for example, a wireless radio frequency communication device 1703 (including one or more antennae 1310) and any suitable optical communication device 1704 such as, for example, an infrared communication device. The wireless radio frequency communication device 1703 may be configured to allow communication between the bot 110 and, for example, the control server 120 and/or other different bots 110 over any suitable wireless protocol. For exemplary purposes only, the wireless protocol for communicating with the control server 120 may be the wireless 802.11 network protocol (or any other suitable wireless protocol). Communications within the bot control system 1220 may be through any suitable communication bus such as, for example, a control network area bus. It is noted that the control server 120 and the bot control system 1220 may be configured to anticipate momentary network communication disruptions. For example, the bot may be configured to maintain operation as long as, for example, the bot 110 can communicate with the control server 120 when the bot 110 transits a predetermined track segment and/or other suitable way point. The optical communication device 1704 may be configured to communicate with, for example, the bot transfer stations for allowing initiation and termination of charging the capacitor 1400. The bot 110 may be configured to communicate with other bots 110 in the storage and retrieval system 100 to form a peer-to-peer collision avoidance system so that bots can travel throughout the storage and retrieval system 100 at predetermined distances from each other as will be described below.

0058Referring again to <figref idref="f0017">Fig. 13</figref>, the bot 110 can determine its position within the storage and retrieval system 100 for transitioning through the storage structure 130 as described above through, for example, bot localization. In one exemplary embodiment bot localization may be derived through one or more of bot odometry, slat counting, index counting and bar code reading. As described above, the bot odometry may be provided from encoders associated with, for example, wheels 1211-1214 (<figref idref="f0012">Fig. 10</figref>). It is noted that encoder information from each wheel 1211-1214 may be averaged and scaled in any suitable manner to provide a distance traveled by the bot. In alternate embodiment, the distance traveled by the bot may be obtained from the wheel encoder information in any suitable manner. The slat counting may be provided by, for example, the slat sensors 1711 as the bot travels through the picking aisles. The slat counting may supplement the odometry information when the bot is within the picking aisles. The index counting may be provided, by for example, the line sensors 1712 as the bot passes over crossed sections of the guidance lines 1810-1817 (<figref idref="f0018">Fig. 14</figref>). The index counting may supplement the bot odometry when the bot is traveling on the transfer deck 130B. Bar code reading may be provided by bar code scanner 1710. The bar code reading may be configured to allow the bot 110 to determine an initial position of the bot such as when the bot is powered up from an off or dormant state. The bar codes may be located at transfer areas 295 or any other suitable location within the storage structure 130 for initializing the bot 110. Bar codes may also be located within the picking aisles and on the transfer deck to, for example, confirm bot location and correct for missed slats or indexes. The on-board computer 1701 of the bot 110 may be configured to use any suitable combination of bot odometry, slat counting, index counting and bar code reading to determine the bot's 110 position within the storage structure 130. In alternate embodiments, the computer 1701 may be configured to determine the location of the bot using only one or any suitable combination of bot odometry, slat counting, index counting and bar code reading. In still other alternate embodiments, the location of the bot may be determined in any suitable manner such as through, for example, an indoor spatial positioning system. The indoor spatial positioning system may be substantially similar to a global positioning system and use any suitable technique for determining the position of an object such as, for example, acoustic, optical, or radio frequency signaling.

0059In one exemplary embodiment, one or more of the sensors 1710-1716 described above may allow for dynamic positioning of bots 110 within the picking aisles 130A in any suitable manner. The position at which the bot 110 is stopped for dynamically allocating case units may be determined by, for example, the control server 120, the control system 1220 of the bot or by a combination thereof. For example, dynamic allocation of the storage space may be determined by, for example, the control server 120 in any suitable manner such that any open storage spaces in the storage structure 130 are filled with case units having a size capable of fitting within those open storage spaces. The control server may communicate to the appropriate components of the storage and retrieval system 100, for example, a location of a predetermined storage location and an appropriately sized item or case units for placement in the predetermined storage location. That item may be transferred into the storage and retrieval system 100 where a bot 110 delivers the item to the predetermined storage location. As a non-limiting example, the sensors 1710-1716 of the bots 110 may count slats 620L1, 620L2 (<figref idref="f0007">Fig. 6B</figref>) and/or detect edges of case units on the storage shelves for dynamically positioning the bots for placing the item in the predetermined storage location. Dynamically positioning the bots 110 and/or the dynamic allocation of shelf storage space may allow for the positioning of case units having varying lengths in each storage bay 510, 511 (<figref idref="f0005">Fig. 5</figref>) such that the use of the storage space is maximized. For example, <figref idref="f0019">Fig. 15A</figref> illustrates a storage bay 5000 divided into storage slots S1-S4 as is done in conventional storage systems. The size of the storage slots S1-S4 may be a fixed size dependent on a size of the largest item (e.g. item 5011) to be stored on the shelf 600 of the storage bay 5000. As can be seen in <figref idref="f0019">Figure 15A</figref>, when case units 5010, 5012, 5013 of varying dimensions, which are smaller than item 5011, are placed in a respective storage slot S1, S2, S4 a significant portion of the storage bay capacity, as indicated by the shaded boxes, remains unused. In accordance with an exemplary embodiment, <figref idref="f0019">Fig. 15B</figref> illustrates a storage bay 5001 having dimensions substantially similar to storage bay 5000. In <figref idref="f0019">Figure 15B</figref> the case units 5010-5016 are placed on the shelf 600 using dynamic allocation. As can be seen in <figref idref="f0019">Figure 15B</figref>, dynamically allocating the storage space allows placement of case units 5014-5016 on shelf 600 in addition to case units 5010-5013 (which are the same case units placed in storage bay 5000 described above) such that the unused storage space, as indicated by the hatched boxes, is less than the unused storage space using the fixed sized slots of <figref idref="f0019">Fig. 15A. Fig. 15C</figref> illustrates a side by side comparison of the unused storage space for the fixed slots and dynamic allocation storage described above. It is noted that the unused storage space of bay 5001 using dynamic allocation may be decreased even further by decreasing the amount of space between the case units 5010-5016 which may allow for placement of additional case units on the shelf 600. As may be realized, as case units are placed within the storage structure the open storage spaces may be analyzed, by for example the control server 120, after each item placement and dynamically re-allocated according to a changed size of the open storage space so that additional case units having a size corresponding to (or less than) a size of the reallocated storage space may be placed in the re-allocated storage space.

0060As described above, the components of the storage and retrieval system described herein are in communication with and/or controlled by control server 120 as shown in <figref idref="f0020">Figs. 16</figref> and <figref idref="f0021">17</figref>. The control server 120 may include a collection of substantially concurrently running programs that are configured to manage the storage and retrieval system 100 including, for exemplary purposes only, controlling, scheduling and monitoring the activities of all active system components, managing inventory and pickfaces, and interfacing with the warehouse management system 2500. It is noted that a pickface as used herein may be one or more merchandise case units placed one behind the other in a storage space or area of a storage shelf to be used in pick transactions for filling customer orders. In one example, all case units forming a given pickface are of the same stock keeping unit (SKU) and originally from the same pallet. In alternate embodiments, each pickface may include any suitable case units. Each pickface may correspond to all or part of a bot load 750-753 (<figref idref="f0008">Fig. 7B</figref>). Conversely, the bot load may be established based on a pickface determination. As may be realized the determination of the pickfaces may be variable within the storage and retrieval system such that the size and locations of the pickface are dynamically changeable. It is also noted that interfacing with the warehouse management system allows the control server 120 to receive and execute pallet orders and to submit and execute replenishment orders as will be described below. The active system components may be the physical entities that act upon the case units to be stored and retrieved. The active system components may include, as a non-limiting example, items such as bots, in-feed and out-feed stations, multilevel vertical conveyors, the network and user interface terminals. In alternate embodiments, the active system components may also include bot transfer stations. The control server 120 may be configured to order the removal of case units from the storage and retrieval system for any suitable purpose, in addition to order fulfillment, such as, for example, when case units are damaged, recalled or an expiration date of the case units has expired. In one exemplary embodiment, the control server 120 may be configured to give preference to case units that are closer to their expiration date when fulfilling orders so those case units are removed from the storage and retrieval system before similar case units (e.g. with the same SKU) having later expiration dates. In the exemplary embodiments, the distribution (e.g. sortation) of case units in the storage and retrieval system is such that the case units can be provided for delivery to a palletizing station in any suitable order at any desired rate using only two sortation sequences. The control server 120 may be configured to fulfill orders so that the cases are provided by the bots 110 to respective multilevel vertical conveyors 150B in a first predetermined sequence (e.g. a first sortation of case units) and then removed from the respective multilevel vertical conveyors 150B in a second predetermined sequence (e.g. a second sortation of case units) so that the case units may be placed on pallets (or other suitable shipping containers/devices) in a predetermined order for building mixed pallets 9002 (<figref idref="f0034">Fig. 28</figref>). For example, in the first sortation of case units the bots 110 may pick respective case units (e.g. case unit) in any order. The bots 110 may traverse the picking aisles and transfer deck (e.g. circulate around the transfer deck) with the picked item until a predetermined time when the item is to be delivered to a predetermined multilevel vertical conveyor 150B. In the second sortation of case units, once the case units are on the multilevel vertical conveyor 150B the case units may circulate around the conveyor until a predetermined time when the item are to be delivered to the out-feed transfer station 160. Referring to <figref idref="f0034">Fig. 28</figref>, it is noted that the order of case units delivered to the pallets may correspond to, for example, store plan rules 9000. The store plan rules 9000 may incorporate, for example, an aisle layout in the customer's store or a family group of case units corresponding to, for example, a particular location in the store where the pallet will be unloaded or a type of goods. The order of case units delivered to the pallets may also correspond to characteristics 9001 of the case units such as, for example, compatibility with other case units, dimensions, weight and durability of the case units. For example, crushable case units may be delivered to the pallet after heavier more durable case units are delivered to the pallet. The first and second sortations of the case units allows for the building of mixed pallets 9002 as described herein.

0061The control server 120 in combination with the structural/mechanical architecture of the storage and retrieval system enables maximum load balancing. As described above, the storage spaces/storage locations are decoupled from the transport of the case units through the storage and retrieval system. For example, the storage volume (e.g. the distribution of case units in storage) is independent of and does not affect throughput of the case units through the storage and retrieval system. The storage array space may be substantially uniformly distributed with respect to output. The horizontal sortation (at each level) and high speed bots 110 and the vertical sortation by the multilevel vertical conveyors 150B substantially creates a storage array space that is substantially uniformly distributed relative to an output location from the storage array (e.g. an out-feed transfer station 160 of a multilevel vertical conveyor 150B). The substantially uniformly distributed storage space array also allows case units to be output at a desired substantially constant rate from each out-feed transfer station 160 such that the case units are provided in any desired order. To effect the maximum load balancing, the control architecture of the control server 120 may be such that the control server 120 does not relate the storage spaces within the storage structure 130 (e.g. the storage array) to the multilevel vertical conveyors 150B based on a geographical location of the storage spaces (which would result in a virtual partitioning of the storage spaces) relative to the multilevel vertical conveyors 150B (e.g. the closest storage spaces to the multilevel vertical conveyor are not allocated to cases moving from/to that multilevel vertical conveyor). Rather, the control server 120 may map the storage spaces uniformly to each multilevel vertical conveyor 150B and then select bots 110, storage locations and output multilevel vertical conveyor 150B shelf placement so that case units from any location in the storage structure come out from any desired multilevel vertical conveyor output (e.g. at the out-feed transfer stations) at a predetermined substantially constant rate in a desired order for building the mixed pallets 9002 (<figref idref="f0034">Fig. 28</figref>).

0062The control server 120 may include one or more server computers 120A, 120B and a storage system or memory 2400. In alternate embodiments the control server 120 may have any suitable configuration. In one exemplary embodiment, the server computers 120A, 120B may be configured substantially identically to each other where one server computer 120A is designated as a primary server and the other server computer 120B is designated as a secondary server. In normal operation the storage and retrieval system, such as storage and retrieval system 100, is substantially controlled by the primary server computer 120A. In the event of a failure of the primary server computer 120A, the secondary server computer 120B may be configured to assume operation of the storage and retrieval system 100 in any suitable manner. For example, the secondary server computer 120B may be configured to initialize itself with operating information stored in databases 2401 (<figref idref="f0021">Fig. 17</figref>) of, for example the storage system 2400. In alternate embodiments the secondary server computer 120B may be configured to reconstruct the operational databases based on, for example, database snapshots or log files, reboot and then initialize itself from the restored databases. While only two server computers 120A, 120B are shown, in alternate embodiments there may be any suitable number of server computers connected to each other so that there are any suitable number of levels of redundancy. In one exemplary embodiment, the control server 120 may include or be coupled to any suitable number of host computers, where each of the host computers is configured to operate one or more levels of the storage structure 130. In the event of a host computer failure, the control server 120 may be configured to assign operation of the one or more levels of the failed host computer to another host computer so that the storage and retrieval system operates substantially uninterrupted. In alternate embodiments, the control server 120 may be configured to assume operational control over the one or more levels of the failed host computer.

0063The storage system 2400 of the control server 120 may be physically separated from the server computers 120A, 120B. In one exemplary embodiment, the storage system 2400 may be located in the same facility as the control server 120 while in other alternate embodiments the storage system 2400 may be located off-site from the facility in which the control servers 120A, 120B are located. In still other alternate embodiments, the storage system may be integral to one or more of the server computers 120A, 120B. The storage system 2400 may be configured with any suitable number of storage locations for providing data redundancy for holding operational databases and other runtime data. The control server 120 may be configured to access, update or otherwise manage the operational databases 2401 and other runtime data (such as for example, event logs 2402 (<figref idref="f0021">Fig. 17</figref>) or other suitable data) in any suitable manner and for any suitable purposes. The control server 120 may also be configured to record a maintenance history for each component (e.g. bots, transfer stations, conveyors, etc.) of the storage and retrieval system. In the case of the bots 110, each bot may be configured to send the control server 120 information pertaining to the maintenance of the bot (e.g. when the bot is charged, the distance traveled by the bot, repair information or any other suitable information) at any suitable time intervals. In other exemplary embodiments, the control server 120 may request maintenance information from the bots 110.

0064The control server 120 may be configured to communicate with the active system components of the storage and retrieval system 100 through the network 180. As described above, the network 180 may be a wired network, a wireless network, or a combination of wired and wireless networks. In one exemplary embodiment, all fixedly located components of the storage and retrieval system 100 may be connected to the control server 120 through a wired portion of network 180 while the movably located components of the storage and retrieval system (such as e.g. the bots 110) may be connected to the control server through a wireless portion of the network 180. In alternate embodiments fixed elements may be connected to the control server 120 through wireless communication. In still other alternate embodiments the movable elements may be connected to the control server 120 through any suitable wired communications.

0065The network 180 may be a single physical network or be divided into separate physical networks. For example, in one exemplary embodiment, each level of the storage structure 130 may have its own individual communication network, which in turn communicates with the control server 120. Each individual communication network may operate on, for example, a different communication frequency than other different ones of the individual communication networks. In other exemplary embodiments, groups of levels (e.g. one or more levels) of the storage structure 130 may share individual networks, which are in turn in communication with the control server 120. It is noted that the control server 120 may be configured to communicate with the one or more communication networks using a shared network or one or more private networks.

0066In one exemplary embodiment, as can be seen in <figref idref="f0021">Fig. 17</figref>, the control server 120 includes a front end 2510 and an activity controller 2520. It is noted that while the control server 120 is described as having the configuration shown in <figref idref="f0021">Fig. 17</figref>, in alternate embodiments the control server 120 may have any suitable configuration. In this exemplary embodiment, the front end 2510 may include any suitable programs or modules for carrying out the activities of the storage and retrieval system. As a non-limiting example, the front end 2510 may include an order manager 2511, an inventory manager 2512 and a management server 2513. The order manager 2511 may be configured to process orders submitted by the warehouse management system 2500.

0067The inventory manager 2512 may be configured to provide inventory services to any suitable components of the storage and retrieval system 100 and/or the warehouse management system 2500. The management server 2513 may be configured to monitor the processes of the storage and retrieval system 100. The activity controller 2520 may include any suitable programs or modules for controlling the activities of the storage and retrieval system 100. For example, the activity controller 2520 may include a bot management subsystem 2521, a resource manager 2522, a controller monitor 2523 and an event processor 2524. The bot management subsystem 2521 may be configured to manage bot movement and transport activity. The resource manager 2522 may be configured to manage the activities of the active and passive (e.g. bot charging stations, etc.) components of the storage and retrieval system (which in alternate embodiments may include bot activity). The controller monitor 2523 may be configured to monitor various external controllers 2550 for operating one or more active components such as, for example, components 140, 150A, 150B, 160A, 160B, 210, 220, 2501, 2503 of the storage and retrieval system 100. The event processor 2524 may be configured to monitor events such as picking or placing of case units within the storage structure 130, available storage locations, active bots, or any other suitable events and update one or more databases 2401 and/or event logs 2402 accordingly.

0068In one exemplary embodiment one or more user interface terminals or operator consoles 2410 may be connected to the control server 120 in any suitable manner, such as through, for example, network 180. In one exemplary embodiment, the user interface terminals 2410 may be substantially similar to computer workstations 700 (<figref idref="f0008">Fig. 7A</figref>). The one or more user interface terminals 2410 may be configured to allow an operator of the storage and retrieval system 100 to control one or more aspects of the storage and retrieval system 100. In one exemplary embodiment, one or more of the user interface terminals 2410 may allow for manual entry/modification/cancellation of customer orders and replenishment orders. In another example, the user interface terminals 2410 may allow for inspection, modification or otherwise accessing/entering data within the databases of the system 100 such as, for example, the databases maintained by the inventory manager 2512. One or more of the user interface terminals 2410 may allow an operator to graphically view inventory tables and provide a mechanism for specifying criteria for which case units to display (e.g. showing information for case units with a specified SKU, information about a SKU, how full a specified storage level is, the status of pick or replenishment orders, or any other suitable information) to the user of the user interface terminal 2410. One or more of the user interface terminals 2410 may be configured to allow for the display of current order, historical order and/or resource data. For example, the historical data may include the origins of a specified item in storage, fulfilled orders or other suitable historical data (which may include historical data pertaining to the storage and retrieval system components). Current order data may include, for example, current order status, order placement dates, item SKUs and quantities or any other suitable information pertaining to current orders. The resource data may include, for example, any suitable information about the active or passive resources within the storage and retrieval system. The user interface terminals 2410 may be configured to allow generation of any suitable reports 2699 (<figref idref="f0022">Fig. 18</figref>) pertaining to the operation of the storage and retrieval system 100. The user interface terminals 2410 may provide a "real time" or up to date representation of the picking structure. In one example, the picking structure representation may be a graphical representation presented on, for example, a display of the user interface terminal 2410 indicating for example, a status of one or more components of the storage and retrieval system. For example, a graphical layout of the entire storage and retrieval system 100 may be displayed such that a location of the bots 110 for each level is shown, the case units in each storage slot are shown, the position of case units being transported within the storage structure are shown or any other suitable graphical information pertaining to the operation of the storage and retrieval system 100 may be shown. One or more of the user interface terminals 2400 may be configured such that an operator can change a status of the storage and retrieval system resources, such as, for exemplary purposes only, take an aisle, conveyor and/or bot (and/or any other suitable system resource) out of service or place a system resource back in service as well as add new resources to (and/or remove resources from) the system 100.

0069Referring also to <figref idref="f0022">Fig. 18</figref>, an exemplary operation of the storage and retrieval system will be described in accordance with an exemplary embodiment. The warehouse management system 2500 receives a customer order and examines the order to determine which case units in the order can be fulfilled by the storage and retrieval system 100. Any suitable portion of the order that can be fulfilled by the storage and retrieval system 100 is forwarded to the control server 120 by the warehouse management system 2500. It is noted that portions of the order that are not filled by the storage and retrieval system may be fulfilled manually such that the storage and retrieval system is capable of partial pallet builds. For exemplary purposes only, an order where case units are requested to be picked from the storage and retrieval system 100 and placed onto one or more pallets may be called a "pallet order". Conversely, orders issued by the storage and retrieval system 100 to replenish case units into the storage and retrieval system 100 may be called, for exemplary purposes "replenishment orders". The orders may be broken down into tasks for the bots 110 to execute. For exemplary purposes only, a bot task which is part of a pallet order may be called a picking task and a bot task that is part of a replenishment order may be called a put away task.

0070When an order is to be fulfilled the warehouse management system 2500 issues an execute order message (<figref idref="f0025">Fig. 19</figref>) to, for example, the order manager 2511. The execute order message refers to a pallet identification specified at the time of order entry and it specifies an out-feed station 2860A, 2860B and/or palletizing station 2820A, 2820B. As can be seen in <figref idref="f0021">Figs. 17</figref> and <figref idref="f0022">18</figref>, the order manager 2 511 may be configured to receive the orders from the warehouse management system 2500. The order manager 2511 may issue tasks to individual level managers 2608 to pick up and/or put away case units. It is noted that communication between, for example, the order manager 2511 and the level managers 2608 may be over any suitable communication channel/protocol including, but not limited to, a three-phase commit protocol configured to substantially ensure that the communications are not duplicated in the event of, for example, a system outage or interruption. The level managers 2608 may be configured to control a respective level of the storage structure 130. In one exemplary embodiment, there may be one level manager 2608 per storage structure level. In alternate embodiments, there may be more than one level associated with each level manager 2608. In still other alternate embodiments, there may more than one level manager 2608 associated with each level in the storage structure 130. Each level manager 2608 may be configured to receive tasks to be completed by the respective level and issue tasks for the respective bots 110A, 110B, 110N to execute. In this example, bots 110A correspond to bots of, for example, level 1 of the storage structure 130, bots 110B correspond to bots of, for example, level 2 of the storage structure and bots 110N correspond to, for example bots of level "n" of the storage structure, where the storage structure has any suitable number of levels.

0071Referring also to <figref idref="f0023">Fig. 18A</figref>, each level manager 2608 may be split into, for example, two services such as a front end service 2650 and a backend or bot service 2651. The front end service 2650 may include, for example, a control service 2653 and an idle bot manager 2652. The back end 2651 may include traffic managers 2654 and bot proxy 2680. A structure manager 2656 and a reservation manager 2608A may be shared by the front end service 2650 and the back end service 2651. In alternate embodiments the level managers 2608 may have any suitable configuration for controlling one or more respective levels of the storage and retrieval system 100. In one example, pick and put requests may enter a control service 2653 through the front end 2650. For example, the front end 2650 may receive requests from, for example, the order manager 2511 and/or inventory manager 2512 and dispatch those requests to idle bots 110 in the form of bot jobs or tasks. In alternate embodiments the front end may receive requests from the back end 2651. The front end may be configured to convert the request to a job and assign that job a unique identification. The job may be placed in one or more queues 2655 (e.g. a high priority queue or a low priority queue) that are shared between an idle bot manager 2652 and the control service 2653. Jobs may be classified as high priority when, for exemplary purposes only, the jobs are needed or processing a current order. Jobs may be classified as low priority, for exemplary purposes, when the jobs are needed for processing orders to be fulfilled at a later time (e.g. after the current order). It is noted that the status of jobs may change from low to high priority as other jobs are completed. In alternate embodiments the jobs may have any suitable classification for prioritizing the jobs. If there are no idle bots 110 to perform a job (as determined by e.g. the idle bot manager 2652 as described below) the front end relinquishes control to an event loop which will notify the front end when one or more bots register as idle so that one of the one or more idle bots can be assigned the job.

0072The idle bot manager 2652 may be configured to maintain a list of, for example, bot proxies representing idle bots 110 (e.g. bots not actively transporting, picking or putting case units within the storage and retrieval system 100). The bot proxy list may be actively updated to reflect changes in bot status from, for example, idle to active and vice versa. The idle bot manager 2652 may be configured to determine, in any suitable manner, the best bot 110 for executing a task and inform the associated bot proxy 2680 for executing the task. In one exemplary embodiment and for exemplary purposes only, when determining which bot should be assigned a given job, the idle bot manager 2652 may analyze one or more of whether a bot is already in a desired picking aisle and directionally oriented for picking an item (if the job is a pick), if there is a bot 110 blocking an aisle needed for fulfilling an order so that the bot can be moved to grant access to the aisle, and whether there are any outstanding high priority jobs to be fulfilled before low priority jobs are considered.

0073When jobs are assigned to a bot, the idle bot manager 2652 may be configured to determine a travel route for fulfilling the job. The idle bot manager 2652 may be in communication with any suitable components of the storage and retrieval system, such as the structure manager 2656, which provide any suitable information such as, for example, information for analyzing load balancing of the transfer decks, disabled areas of the storage structure 130 (e.g. places where maintenance is being performed), a position of the bot relative to a pick or put position for the job, the distance to be traveled by the bot for completing the job or any other suitable characteristics of the storage and retrieval system 100 when determining a route for the bot. It is noted that the structure manager 2656 may also be configured to monitor and track any suitable changes to the storage structure, such as for example, bad or broken storage slats or legs 620, 620L1, 620L2 (<figref idref="f0006">Figs. 6A</figref> and <figref idref="f0007">6B</figref>), undetectable index markers, added storage, travel and/or transfer areas and disabled or removed areas and convey the changes in the storage structure 130 to, for example, the idle bot manager 2652 and/or bot proxies 2680 for the determination of the bot travel routes.

0074The bot proxy 2680 (<figref idref="f0023">Fig. 18A</figref>) receives the jobs for a respective bot 110 from, for example, the idle bot manager 2652 and takes control of the task until, for example, a completion of the task or an unrecoverable bot failure. The bot proxy 2680 may be a "stand in" for a respective bot 110 on the control server 120 and be configured to, for example, manage the detailed execution of tasks by a respective bot and track the task's execution. The bot proxy 2680 may be configured to receive any suitable information from, for example, the idle bot manager 2652. In one example, a bot proxy owner 2680A may be configured to receive a list of bots expected to perform respective tasks and any other suitable information (e.g. storage structure map, pointers to level manager interfaces and objects, etc.) for the operation of the bot proxy owner 2680A. The bot proxy owner 2680A may pass information to one or more bot proxies 2680 for each bot selected to perform a job. The bot proxy 2680 may be configured to provide a status of the bot to any suitable entity (e.g. idle bot manager 2652, operator workstations, etc.) of the storage and retrieval system 100. In one example, if the bot proxy 2680 determines a bot 110 cannot perform a task assigned to the bot 100, the bot proxy 2680 may be configured to notify the control service 2653 and reregister the bot as idle with the idle bot manager 2652. The bot proxy 2680 may communicate with, for example, a traffic manager 2654 and the reservation manager 2608A to gain access to one or more of the transfer deck 130B, transfer areas 295 and picking aisles 130A (or in alternate embodiments bot transfer stations 140). Upon completion of a task, the bot proxy 2680 registers as idle with the idle bot manager 2652 and indicates an identification of the task completed by the bot 110. If the task failed, the bot proxy 2680 registers as idle, indicates an identification of the task and indicates why the task failed.

0075Referring again to <figref idref="f0022">Fig. 18</figref>, the order manager 2511 may be configured to send requests for reservation to one or more multilevel vertical conveyor controllers 2609, which may include multilevel vertical conveyor managers 2609M. Referring also to <figref idref="f0024">Fig. 18B</figref> it is noted that reservations as described herein may be organized in a queue 2690 having for example, an active slot (e.g. the current job) associated with an active reserver and queued slots 2692-2694 associated with waiting reservers 2692A-2694A, where a reserver is for example, a bot, multilevel vertical conveyor, a transfer station, or any other suitable component of the storage and retrieval system 100. In alternate embodiments the reservations may be handled in any suitable manner. There may be one or more multilevel vertical conveyor managers 2609M associated with each multilevel vertical conveyor 150. In alternate embodiments, there may be one or more multilevel vertical conveyors 150 associated with each multilevel vertical conveyor managers 2609M. The multilevel vertical conveyor managers 2609M may be configured to, for example, keep track of the operation of respective multilevel vertical conveyors 150 and respond to requests for reservations of the multilevel vertical conveyors 150 for transporting case units to and from each level of the storage structure 130. Each multilevel vertical conveyor manager 2609M may be configured to coordinate with its respective multilevel vertical conveyor(s) 150 in any suitable manner such as by, for example, using synchronized time kept using a network time protocol.

0076The inventory manager 2512 is configured to receive the replenishment orders from the warehouse management system. The inventory manager 2512 may be configured to access and/or maintain one or more suitable databases of the storage system 2400 for tracking inventory and/or issuing or aiding in the issuance of bot tasks. In one example the inventory manager 2512 may be in communication with one or more of an item master database 2601, an inventory database 2602 and a storage and retrieval system map database 2603 (and any other suitable databases). The item master database 2601 may include a description of the stock keeping units (SKUs) that are handled by or otherwise located in the storage and retrieval system 100. The inventory database 2602 may include, for example, the location of each item inventoried in the storage and retrieval system 100. The storage and retrieval system map database 2603 may include a substantially complete description of the physical structure of the storage and retrieval system 100 including, but not limited to, each storage level, aisles, decks, shelves, transfer stations, conveyors and any other suitable structures within the storage and retrieval system. In alternate embodiments the storage system 2400 may include any suitable databases for providing operational information to, for example, the order manager 2511 and/or the inventory manager 2512. In one exemplary embodiment, the inventory manager 2512 may be configured to provide any suitable inventory information to other suitable components of the storage and retrieval system such as, for exemplary purposes only, the order manager 2511 as described herein to allow the order manager 2511 to reserve case units against an order. The reservation of case units substantially prevents more than one bot 110 from attempting to retrieve the same item from storage. The inventory manager 2512 also allows for the assignment and reservation of a pickface for putting away an inbound item such as during replenishment of the storage and retrieval system 100. In one exemplary embodiment, when a storage slot/space becomes available in the storage structure 130, the inventory manager 1512 may assign a fictitious item (e.g. an empty case) to the empty storage slot. If there are adjacent empty slots in the storage structure the empty cases of the adjacent storage slots may be combined to fill the empty space on the storage shelf. As may be realized, the size of the slots may be variable such as when dynamically allocating shelf space. For example, referring to <figref idref="f0019">Fig. 15B</figref>, instead of placing case units 5011 and 5012 on the storage shelf 5001, the storage slots may be dynamically allocated such that the cases 5011, 5012 are replaced by three cases having the size of case unit 5010. In alternate embodiments, the storage slots may also be allocated so that case units that are frequently picked together are located next to each other. When a predetermined pickface is reserved for an item that is being delivered, at least a portion of the empty case sitting in the location where the item is to be placed is replaced by a fictitious item having the features (e.g. size, etc.) of the item being delivered to prevent other inbound case units from being assigned to the predetermined pickface. If the item is smaller than the empty case that it is replacing the empty case may be resized or replaced with a smaller empty case to fill the unused portion of the storage shelf.

0077In this example, the control server 120 includes an executive module 2606, which may be configured to provide an interface between, for example, the control server 120 and an operator. The executive module 2606 may allow monitoring and/or control of the storage and retrieval system operations in any suitable manner such as, for example, through one or more user interface terminals 2410. The executive module 2606 may be configured to provide any suitable reports and allow operator access to an aisle maintenance manager 2607. The aisle maintenance manager 2607 may be configured to allow personnel access into any suitable portion of the storage and retrieval system such that interaction between the personnel and moving components of the storage and retrieval system is substantially eliminated.

0078Referring again to <figref idref="f0020">Figs. 16</figref>, <figref idref="f0021">17</figref> and <figref idref="f0025">19</figref> an exemplary pallet order entry and replenishment process will be described. A portion of, for example, a predetermined time period's (e.g. hour, day, week, or other suitable time period) pallet orders are submitted to the order manager 2511. The order manager records the orders into, for example, an order database 2511B and forwards the information to an inventory planner module 2512B (which may be a subsystem of the inventory manager 2512). It is noted that the inventory planner 2512B may be configured to generate a schedule of replenishment orders based on the pallet orders that will maintain a sufficient quantity and composition of picking stock to, for example, substantially prevent an unavailability of case units throughout the order fulfillment process for the predetermined time period and to prepare the storage and retrieval system for, for example, the start of the next predetermined order fulfillment time period. In one exemplary embodiment, the inventory planner 2512B may be configured to sort the orders by time and using, for example, a current inventory as a beginning balance, the inventory planner 2512B may compute an inventory level that would result at the end of each predetermined order fulfillment time period. Based on, for example, per-SKU preorder thresholds, per-SKU economic order quantity, target end of predetermined time period balances, and an inventory calculated after each order, the inventory planner 2512B computes a schedule of planned replenishment orders and submits the replenishment orders to the warehouse management system 2500. As new pallet orders are submitted to the order manager 2511, the above computations are repeated, which may result in a modification of the replenishment orders. In alternate embodiments the inventory storage and retrieval system 100 may be maintained in any suitable manner.

0079Referring also to <figref idref="f0026">Fig. 20</figref>, as each order is fulfilled, bots 110 for their respective storage levels 2801, 2802 deliver the picked case units to output transfer areas 2840A, 2840B. The output transfer areas 2840A, 2840B may be substantially similar to transfer area 295 described above. Bots 110 at the output transfer areas 2840A, 2840B transfer the case units to the multilevel vertical conveyor for transport to one or more out-feed transfer stations 2860A, 2860B. In alternate embodiments the bots 110 may deliver the picked case units indirectly to the multilevel vertical conveyor 150B through, for example, bot transfer stations 140. The out-feed transfer stations 2860A, 2860B may be substantially similar to out-feed transfer stations 160 described above with respect to, for example <figref idref="f0001">Fig. 1</figref>. The case units are transported from out-feed transfer stations 2860A, 2860B to a respective one of the palletizing stations 2820A, 2820B by one or more suitable conveyors. In this example, there are two accumulation conveyors feeding each palletizing station 2820A, 2820B. In alternate embodiments there may be more or less than two conveyors feeding each palletizing station 2820A, 2820B. Each set of accumulation conveyors 2870, 2871 may be managed by, for example, the order manager 2511 or any other suitable subsystem of the control server 120 for providing a buffer system to each of the respective palletizing stations 2820A, 2820B. For example, out-feed transfer station 2860A can be filling conveyor 1 of the set of conveyors 2870 while the palletizing station 2820A is emptying conveyor 2 of the set of conveyors 2870 so that the rate of transferring case units to the out-feed stations does not have to be matched to the rate at which the palletizing station 2820A places the case units on a pallet. In alternate embodiments, any suitable buffer system may be provided for supplying case units to the palletizing stations 2820A, 2820B. In still other alternate embodiments, the rates of supplying case units to the out-feed stations 2860A, 2860B may be matched to the rates at which case units are palletized by the palletizing stations 2820A, 2820B.

0080In one exemplary embodiment, the above-described exemplary order fulfillment process may be processed by the order manager 2511 in, for example, any suitable number of phases. For exemplary purposes only, in this exemplary embodiment the order manager 2511 may process the pallet order in a transaction planning phase and a transaction execution phase. In the transaction planning phase the order manager 2511 may reserve the multilevel vertical conveyor and pickface resources for delivering a predetermined number of case units of each ordered SKU to the palletizing station in a predetermined sequence. The order manager 2511 may generate a series of pick transactions that will fulfill the pallet order. The transaction planning phase may be performed for an entire pallet order, as a batch, before the first pick transaction is released for execution. In alternate embodiments the pick transactions may be generated and executed in any suitable manner.

0081The pick transactions may be generated by the order manager 2511 in any suitable manner. In one exemplary embodiment, the pick transactions may be generated by choosing a multilevel vertical conveyor, choosing an output transfer station/storage level and choosing a pickface. In one exemplary embodiment, the next unreserved shelf 730 on an outbound multilevel vertical conveyor 150B that feeds a designated palletizing station 2820A, 2820B is reserved for picked case units. In alternate embodiments, any suitable shelf 730 of any suitable outbound multilevel vertical conveyor may be reserved in any suitable manner.

0082The output transfer station/storage level is chosen such that the output transfer station 2840A, 2840B is located on a level including a pickface for the SKU. To be selected, the output transfer station 2840A, 2840B must not be scheduled as busy at the time the target multilevel vertical conveyor platform or shelf 730 arrives, and the target shelf 730 must not be scheduled to arrive at the output transfer station for at least X seconds, where X is the time in seconds that is estimated as required for a bot 110 to pick the ordered item(s) and travel to the output transfer station 2840A, 2840B. In alternate embodiments, where there is no output transfer station that satisfies the above criteria on a storage level including the pickface for the SKU, the target multilevel vertical conveyor shelf 730 is left empty and the next platform is reserved in its place. The output transfer station 2840A, 2840B selection process may be repeated until at least one candidate output transfer station meets the criteria.

0083The order manager 2511 may request from, for example, the inventory database 2602 a list of all available pickfaces for the specified SKU along with, for example, their attributes such as number of cases, locations, induction and expiration dates. In alternate embodiments the order manager 2511 may request any suitable information regarding the case units being picked. The order manager 2511 may request from the associated multilevel vertical conveyor manager 2609M the availability of all output transfer stations 2840A, 2840B that feed the designated palletizing station 2820A, 2820B. The order manager 2511 may determine which output transfer stations 2840A, 2840B are eligible for the pick transaction according to the above-noted criteria, and select the highest ranked candidate from the eligible output transfer stations 2840A, 2840B based on, for example, one or more of the following factors:

0084Scarcity of levels on which the SKU for the case units to be picked are located. For example, if the SKU for a particular order Line exists on more than P (plentiful) number of levels, then order manager 2511 looks ahead N order lines. If an order line within these N order lines is for a SKU that exists on fewer than S (scarce) number levels, then the output transfer station/level receives a negative ranking for this factor, reducing the likelihood that it will be used for the current order line and thereby potentially block use of this level for a scarce SKU. It is noted that P is a value that indicates that a SKU exists on a "plentiful" number of levels, S is a value that indicates that a SKU exists on a "scarce" number of levels and N is a value that specifies the number of multilevel vertical platforms that will be inaccessible by the output transfer station after it makes a transfer.

0085Bot utilization for a given storage level 2801, 2802. For example, the lower the bot utilization is on a given level, the higher the ranking for the transfer station/level. This ranking factor may provide load-balancing for evenly distributing the load of picking tasks throughout the storage structure 130.

0086Opportunity for pick-down. For example, if there is an opportunity to pick-down a pickface, where picking from that pickface causes the pickface to become empty, it is given a higher ranking.

0087Pickface abundance. For example, the greater the number of pickfaces on a given level, the higher the ranking that the level will receive.

0088Maximum delivery window. For example, the delivery window for any given transfer station 2840A, 2840B may be the difference between the arrival time of the target multilevel vertical conveyor shelf 730 at the transfer station 2840A, 2840B and the time of departure of the last bot 110 to drop off at the transfer Station 2840A, 2840B. The larger this time window the less likely it is that a delay in bot 110 travel will result in a delivery that misses the window.

0089Expiration dates. For example, if the SKU requires attention to expiration dates, levels with pickfaces having earlier expiration dates will be given higher scores than those with later expiration dates. In one exemplary embodiment, the weighting of this factor may be inversely proportional to the number of days remaining before expiration, so that it can override certain other criteria if necessary to avoid shipping merchandise too close to its expiration.

0090Minimum picks for an order line. For example, if an order line cannot be filled by a single pick, it must be broken into multiple picks requiring more than one multilevel vertical conveyor shelf 730 and multiple bots 110. Output transfer stations on levels containing a single pickface that would completely fill the order line are given priority over levels that would require splitting an order line into multiple picks.

0091This ranking algorithm produces a value for each factor (the higher the value the more desirable the candidate transfer station for the transaction), and the values for all the factors are then weighted and summed to form a total score for each output transfer station/level. The order manager 2511 selects the output transfer station/level with the highest total score and places a reservation with the multilevel vertical conveyor manager 2609M for that output station for the transaction. It is noted that in alternate embodiments the order manager 2511 may determine which output transfer stations 2840A, 2840B are eligible for the pick transaction in any suitable manner.

0092In one exemplary embodiment, choosing the pickface may include a ranking system that may prioritize the pickfaces based on predetermined factors. In alternate embodiments, the pickface may be chosen in any suitable manner. For exemplary purposes only, the factors used in choosing the pickface may include:

0093Pickfaces on the selected level that would pick-down without depleting all the pickfaces for this SKU on the level are scored higher.

0094Pickfaces that minimize the number of picks for the Order Line are rated higher.

0095Pickfaces with earlier expiration dates, if applicable, or earlier induction dates otherwise, will be given higher priority over those with later expiration or induction dates.

0096Pickfaces located in aisles where no potentially conflicting picks are planned will be given higher priority over pickfaces in aisles where such conflicts might cause bot delays. It in noted that in one exemplary embodiment, once a pickface is selected for a pick transaction, the estimated pick-time is recorded for use in this ranking parameter.

0097Once the pickface has been selected, a reservation for these case units is placed with the inventory manager.

0098The above procedure for transaction planning may generate at least one pick transaction for each order line specifying one or more of the number of cases to be picked, the pickface from which they are to be picked, an output transfer station to which they are to be delivered, the MVC platform on which they are to be placed, and the delivery time-window within which a bot can safely deliver the cases. The at least one pick transaction may be stored in any suitable location, such as in a transaction record in, for example, the storage system 2400.

0099It is noted that some order lines within the pallet order may not be able to be fulfilled by a single pick transaction, either because the ordered quantity of case units is greater than the maximum number of case units per pickface for that SKU, or because it is necessary or advantageous for some other reason to pick from two or more partially-full pickfaces. In this event, successive pick transactions are created using the above noted transaction planning procedure until either the order line is satisfied or an out-of-stock condition occurs.

0100The execution of each transaction, as determined above, generally includes transferring an item(s) from a pickface to a transfer station 2840A, 2840B with a bot 110, transferring the item(s) from the transfer station 2840A, 2840B to one or more out-feed transfer stations 2860A, 2860B with the multilevel vertical conveyor and from the out-feed transfer stations 2860A, 2860B to respective palletizing stations 2820A, 2820B with the accumulation conveyors 2870, 2871 where all or part of the item is transferred to an outbound container. Transfer of item(s) to the transfer station 2840A, 2840B generally involves a bot 110 traversing its respective storage level 2801, 2802 to a designated pickface where the bot 110 picks the specified number of cases for transport to a predetermined output transfer station 2840A, 2840B. At the output transfer station 2840A, 2840B, the item(s) wait for the predetermined multilevel vertical conveyor shelf 730 to arrive for transferring the item(s) onto the shelf 730. As noted above, management of these bot activities may be performed by one or more level managers 2806. In alternate embodiments, the bots may be managed in any suitable manner by any suitable component of the storage and retrieval system 100.

0101In one exemplary embodiment, there may be a separate level manager 2806 for each level within the structure. Each level manager 2806 may be configured to manage all bot activities on a respective level for the performance of pick and put-away tasks. The order manager 2511 may distribute each pick transaction for the pallet order to the appropriate level manager 2608 for the level designated in, for example, the transaction record and awaits notice from the level manager 2608 of completion of transferring the item(s) to the output transfer station 2840A, 2840B.

0102For each pick transaction, the level manager 2608 may provide delivery of the predetermined case units (as indicated in the picking order) to the predetermined transfer station 2840A, 2840B within a predetermined delivery window. The level manager 2608 may assign a bot 110 to perform the task, determine the timing for launching the bot 110 on this task, and instruct a bot proxy 2680 (<figref idref="f0023">Fig. 18A</figref>) to manage the actual movement of the designated bot. It is noted that the bot proxy 2680 may manage the bot's travel by creating a travel route, reserving resources and clearing the bot onto the transfer deck. The bot proxy 2680 may be resident in, for exemplary purposes only, a level manager 2608 (<figref idref="f0023">Fig. 18A</figref>) as described above. In alternate embodiments the bot proxy may be located at any other location of the storage and retrieval system 100. When the bot 110 removes the specified number of case units from the predetermined pickface(s), the level manager 2608 may send a message to the inventory manager 2512 to update the status of the picked case units from "reserved" to "picked". If the picked case units are the last remaining case units in the predetermined pickface, then their removal either creates a new storage slot or enlarges at least one adjacent slot such that the inventory manager 2512 updates a storage slot database 2910 (<figref idref="f0027">Fig. 21</figref>) accordingly.

0103The bot 110 may be configured to notify the level manager 2608 that it has arrived at an output transfer station 2840A, 2840B. The level manager 2608 may confirm with, for example, the multilevel vertical conveyor manager 2609M that the multilevel vertical conveyor 150B is on time and that the predetermined shelf 730 is empty. The level manager 2608 may instruct the bot 110 to place its load (e.g. the picked case units) onto the predetermined multilevel vertical conveyor shelf 730 (<figref idref="f0008">Figs. 7A</figref> and <figref idref="f0026">20</figref>) which has been previously reserved as described above. The transfer of case units from the bot 110 to the multilevel vertical conveyor 150B may be a direct transfer or it may occur through an intermediate transfer arm (as described with respect to <figref idref="f0010 f0011">Figs. 9A-9D</figref>) of the output transfer station 2840A, 2840B. The bot 110 may be configured to inform the level manager 2608 that the case units have been transferred to the multilevel vertical conveyor 150B. The level manager 2608 may inform the order manager 2511 that this stage of the pick transaction has been completed. The multilevel vertical conveyor 150B carries the case units over to an out-feed transfer station 2860A, 2860B (<figref idref="f0026">Fig. 20</figref>). In alternate embodiments, the transfer of case units to the multilevel vertical conveyor may occur in any suitable manner. In still other alternate embodiments, the order manager 2511 may be informed of the transfer of the item(s) to the multilevel vertical conveyor in any suitable manner. It is noted that in one exemplary embodiment, if the bot 110 fails to arrive at the predetermined output transfer station 2840A, 2840B on time, or if the multilevel vertical conveyor managers 2609M inform the level manager 2608 that the multilevel vertical conveyor 150B is not on schedule or that the designated shelf 730 is not empty, the level manager 2608 may be configured to inform the order manager 2511 of the same. The order manager 2511 may be configured to revise the delivery plan for the pallet order and send one or more messages to the level manager 2608 informing the level manager 2608 of the revised picking schedule. The level manager 2608 may be configured to revise the task plans depending on the message (s) and inform the bots 110 of the revised picking schedule. In alternate embodiments, the picking schedule may be revised in any suitable manner if there is a delay in transferring case units to the multilevel vertical conveyor 150B.

0104The multilevel vertical conveyor manager 2609M may be configured to send a message to the out-feed transfer station 2860A, 2860B that services the predetermined palletizing station 2820A, 2820B instructing the out-feed transfer station 2860A, 2860B to extract the item(s) from the predetermined multilevel vertical conveyor shelf and place the item(s) onto the respective accumulator conveyor(s) 2870, 2871 feeding the palletizing station 2820A, 2820B. The out-feed transfer station 2860A, 2860B may be configured to send a message to the multilevel vertical conveyor manager 2609M that the item(s) has been removed from the multilevel vertical conveyor 150B indicating completion of the pick transaction. Once all of the pick transactions for a given pallet order have been completed in a manner substantially similar to that described above, order Execution is complete for the pallet order. In another exemplary embodiment, in an item-level order-fulfillment center using the present invention, the order picking process is very similar to the case-level process described above. However, with the item-level order-fulfillment there are differences: the addition of the removal of the case unit at the palletizing station top to expose individual item units for picking, and cases units are returned to the storage structure after each item pick unless empty. Referring now to <figref idref="f0032">Figs. 26</figref> and <figref idref="f0033">27</figref>, the order picking process begins at depalletization workstations 351001 with the removal of case units from single-product pallets received from suppliers (<figref idref="f0033">Fig. 27</figref>, Block 371200), either immediately upon arrival or after having been placed into temporary storage. At each workstation, the singulated case units immediately have their tops removed (<figref idref="f0033">Fig. 27</figref>, Block 371202). Automated top-removal machines are commercially available that remove the top from, for example, a cardboard case while it travels down a conveyor by first passing it through a light-curtain to measure the case's dimensions and then passing it through cutting blades precisely positioned based on the measured dimensions to cut the case material along all four sides of the box, after which a suction mechanism adheres to the top and pulls it away. With their tops off to expose individual item units for picking, the case's units are then transported to the storage shelves in a manner substantially similar to that described above. The output of each depalletizing workstation 351001, then, is a stream of carrier trays, each holding a single open-top case of merchandise. For example, the case units are transferred to a multi-level vertical conveyor 150A (<figref idref="f0001">Fig. 1</figref>) (<figref idref="f0033">Fig. 27</figref>, Block 371201) and then transferred by bot 110 (<figref idref="f0033">Fig. 27</figref>, Block 371203) to a predetermined storage location (<figref idref="f0033">Fig. 27</figref>, Block 371204). Also in a manner substantially similar to that described above, the bots 110 remove predetermined case units from predetermined storage locations (<figref idref="f0033">Fig. 27</figref>, Block 371205) so that the picked case units can be transferred to multi-level vertical conveyor 150B (<figref idref="f0033">Fig. 27</figref>, Block 371206) and subsequently to a specified order-assembly workstations 351002 (<figref idref="f0033">Fig. 27</figref>, Block 371208) which may be, for example, integral with or adjacent to the palletizing stations 2820A, 2820B (<figref idref="f0026">Fig. 20</figref>). In an item-level order-fulfillment center, order assembly involves a pick-and-pack process in which a specified number of case units are removed from the case units and placed in an outbound shipping container such as a pallet, box or tote. If there are any case units remaining in the case unit after the pick is complete the case unit is returned to a specified location in the storage structure (usually but not necessarily the original location).

0105The present invention, then, makes possible a new operating model for a retail store far different than the conventional self-service store: the automated full-service store, in which customers shop by ordering case units with an electronic shopping terminal instead of collecting them in shopping carts, and the orders are then picked in real time and delivered to pick-up bays for the customers to pick up as they leave the store.

0106Referring now to <figref idref="f0022">Figs. 18</figref>, <figref idref="f0027">21</figref> and <figref idref="f0028">22</figref> an exemplary inventory replenishment will be described in accordance with an exemplary embodiment. In this example, the inventory manager 2512 may be configured to submit a schedule of requested replenishment orders to the warehouse management system 2500. The replenishment orders may be generated based on the inventory removed from the storage and retrieval system 100 during the above-note picking process. In accordance with the replenishment orders, the warehouse management system 2500 may be configured to stage the replenishment orders for the storage and retrieval system 100 substantially at predetermined replenish times indicated by the inventory manager 2512. In alternate embodiments, the replenishment orders may be staged in any suitable manner by any suitable warehouse entity. The warehouse management system 2500 may be configured to send a replenishment order ready message to, for example, the order manager 2511 close to or substantially at the predetermined replenish times. In alternate embodiments, the order manager 2511 may be alerted start a replenishment order in any suitable manner. In one exemplary embodiment, the replenishment order ready message may be received by a replenishment order executor 2511K of the order manager 2511. In another exemplary embodiment, the replenishment order ready message may be received by the inventory manager 2512 through, for example, communications with the order manager 2511. In alternate embodiments the inventory manager 2512 may receive the replenishment order ready message directly from the warehouse management system 2500. In one exemplary embodiment, the replenishment order ready message may indicate that a pallet of case units has been staged at, for example, depalletizing station 200 and that the depalletizer is ready for transferring the case units into the storage and retrieval system. The replenishment order ready message may also include any suitable information pertaining to the case units being staged for replenishment into the storage and retrieval system 100. For exemplary purposes only, in one exemplary embodiment the replenishment order ready message may include the SKU, quantity of case units to be depalletized and a depalletizing station identification. The inventory manager 2512 may be configured to validate the information supplied in the replenishment order ready message and may verify that the in-feed transfer station 170 corresponding to the identified depalletizing station is available. The inventory manager 2512 may be configured to send a message to the warehouse management system 2500 if, upon validation, it is determined that the SKU being replenished is different than the SKU specified in the replenishment order, that there are too many or too few case units being replenished, that the replenishment is being staged earlier or beyond an expected replenishment time specified in the replenishment order, that there is no space available in the storage structure 130, or that there are no resources available (e.g. the in-feed transfer station 210 and/or the multilevel vertical conveyor 150A is not available). In alternate embodiments, a message may be sent to the warehouse management system 2500 upon finding any suitable discrepancy between the case units being staged and the item requested in the replenishment order. In the absence of any discrepancies, the inventory manager 2512 may send a prepare to replenish message to the warehouse management system 2500 indicating replenishment is to begin.

0107In accordance with the exemplary embodiments, the execution of a replenishment order may be substantially similar to the pallet order described above unless otherwise noted. It is noted however, that the flow of case units (e.g. inflow of case units) for the replenishment order is substantially opposite that of the pallet order (e.g. outflow of case units). In one exemplary embodiment, there may be mixed SKUs on a pallet for a replenishment order. In another exemplary embodiment the pallet may include case units having the same SKU. In yet another exemplary embodiment, the case units in a replenishment order may be offloaded from the pallet in any suitable manner. For example, in one exemplary embodiment, the case units may be offloaded in no particular order while in alternate embodiments the case units may be offloaded in a particular sequence.

0108In a manner similar to that described above for the pallet order, the inventory manager 2512 may process the replenishment order in one or more phases. For exemplary purposes only, in one exemplary embodiment, the inventory manager 2512 may process the replenishment order in a transaction planning phase and a transaction execution phase. Transaction planning may include, for example, reserving storage slots on shelves 600 for the replenishment case units, reserving inbound multilevel vertical conveyor resources for transferring the replenishment case units to a predetermined storage structure level and generating one or more put away transactions for transferring the replenishment case units to the storage shelves 600. In one exemplary embodiment, the transaction planning may be performed for the entire replenishment order, as a batch, before the first put away transaction is released for execution. In alternate embodiments, at least a portion of the transaction planning and transaction execution may occur simultaneously.

0109The number of planned transactions in a replenishment order may be calculated in any suitable manner, by for example, any suitable subsystem of the control server 120 such as the inventory manager 2512. In one exemplary embodiment, the number of transactions may be calculated by dividing the number of case units to be depalletized by a standard (e.g. maximum) number of case units per pickface for the specified SKU. The standard number of case units per pickface may depend on the SKU-specific item dimensions, which determines how many case units can fit depth-wise on the storage shelves 600. This division will produce the number of transactions with full pickfaces, plus, if there is a remainder, one additional transaction with the remainder number of cases in a less-than-full pickface.

0110For each planned transaction in a replenishment order, the inventory manager 2512 may submit a batch request to reserve storage slots for all of the pickfaces to be created by put-away transactions involved in the replenishment order. Based on the SKU's dimensions, the inventory manager first determines which levels can store the incoming case units (e.g., levels for which the maximum allowable item height is greater than or substantially equal to the SKU's height). The inventory manager 2512 may obtain, from an available slots database located in, for example, the storage system 2400, a list of the available storage slots on eligible storage levels, along with the attributes for each slot such as slot length and location. The inventory manager 2512 may select and reserve one or more storage slots from the list of available slots to assign to the pickfaces that are created from the replenishment order. The allocation of shelf space (slots) to the storage of case units (pickfaces), such as the dynamic allocation described above with respect to <figref idref="f0019">Figs. 15A-15C</figref>, may provide one or more of spatial diversity of pickface locations, storage capacity utilization and optimized bot picking throughput. As described above, the size, number and location of the storage slots, may be variable. For example, the spatial diversity may maximize the dispersion of pickfaces of a given SKU throughout the structure, both vertically in order to minimize scheduling conflicts at output transfer areas 295 on picking transactions, and horizontally in order to preserve pickface availability in the presence of exceptions (e.g. maintenance, closures, etc.) that prevent access to certain picking lanes. The storage capacity utilization may maximize storage density, i.e. the number of cases that can be stored within the picking structure, by minimizing wasted shelf-space as described above (<figref idref="f0019">Figs. 15A-15C</figref>). Optimization of bot picking throughput may minimize bot travel time when executing picking tasks by storing faster moving SKUs closer to the transfer decks than slower moving SKUs.

0111The inventory manager 2512 may allocate storage slots to pickfaces by scoring each candidate storage slot on one or more of the following factors:

0112Vertical dispersion - For a given slot, the smaller the number of existing pickfaces for the specified SKU on the same level (any aisle) , the higher the score for this factor;

0113Horizontal dispersion - A given slot receives a much higher score on this factor if there are fewer pickfaces for the specified SKU on the same aisle (at any level), than if there are many pickfaces on the same aisle at any level;

0114Space utilization - For a given slot, the smaller the amount of available shelf area that will be wasted as a result of using the slot to store one of the planned pickfaces, the higher the score for this factor; and

0115Bot travel time - The distance of a slot from the nearest transfer deck is used to calculate a score that is inversely proportional to SKU velocity of movement. That is, the nearer the slot is to the transfer deck, the higher its score for a fast-moving SKU and the lower its score for slow-movers. Conversely, the farther the slot is from the transfer deck, the higher its score for a slow-moving SKU and the lower its score for fast-movers.

0116Allocation of the storage slots based on one or more of the above factors produces a value for each factor (the higher the value the more desirable the candidate shelf/slot for the transaction), and the values for all the factors are then weighted and summed to form a total score for each slot that is a candidate for use in storing a pickface in the replenishment order. The inventory manager 2512 may sort the scores to produce a relative ranking of the slots for selecting the required number of slots with the highest total scores and assigning each slot to a specific pickface. In alternate embodiments the allocation of storage slots may be performed in any suitable manner by any suitable subsystem(s) of, for example, the control server 120.

0117The inventory manager 2512, or any other suitable subsystem of the control server 120 may determine the relative sequence in which the case units are to be delivered by a respective multilevel vertical conveyor 150A to respective levels of the storage structure 130. The inventory manager 2512 may maximize the time intervals between successive transactions at each respective in-feed transfer station 170 so that the bot 110 pick-up window for each item is maximized. It is noted that the in-feed transfer stations fed by a given multilevel vertical conveyor 150A are always dedicated to a single replenishment order such that particular sequencing of case units to the conveyors 150A is not needed.

0118The replenishment order process may generate a set of replenishment transactions, each transaction corresponding to a respective pickface, where the transactions indicate a unique pickface identification assigned by the inventory manager 2512 as part of the slot allocation process; the number of case units that are to form the pickface and a corresponding set of unique item identifications, each of which is to be assigned to one of the case units; the slot identification, location (e.g. level, aisle, shelf number, and reference slat number), and dimensions (e.g. length and depth); and the planned execution sequence number of the transaction. In alternate embodiments, the replenishment transactions may include any suitable information for identifying the case units and the locations in which the case units are to be stored.

0119The inventory manager 2512 (or other suitable subsystem of the control server 120) may be configured to perform the transaction execution in any suitable manner. It is noted that resource reservations, such as for the multilevel vertical conveyor shelves 730 and/or the in-feed transfer stations 170, may not be needed for transaction execution because each multilevel vertical conveyor 150A may be dedicated to servicing, for example, a single depalletizing station. In alternate embodiments, the multilevel vertical conveyors may serve more than one depalletizing station such that, for example, the inventory manager reserves system resources in a manner substantially similar to that described above for the fulfillment of pallet orders.

0120In one exemplary embodiment, one or more inspection stations 3010 may be located along the conveyor transferring case units from the depalletizing station 210 to the in-feed transfer station 170. The inspection stations 3010 may be configured to receive inspection parameters including, but not limited to, predetermined item attributes (e.g. item dimensions, weight, SKUs, etc.). The inspection stations 3010 may be configured to sense, for example, the item attributes in any suitable manner as each item passes along the conveyor and compare them to the predetermined item attributes for a given SKU. The inspection station 3010 diverts case units (e.g. rejected case units) that do not meet the inspection parameters to a run-off area for manual inspection and resolution. The inspection station 3010 may be in communication with the control server 120 so the control server is informed of any rejected case units. The inventory manager 2512 of the control server 120 in turn may notify the warehouse management system 2500 of any rejected case units, reduce the number of case units expected to be replenished in the storage and retrieval system 100, and modify the replenishment transaction to account for the rejected item(s).

0121In one example, where a rejected item is determined to satisfy a pick order to a predetermined SKU, but has different dimensions than those specified for the SKU, the inventory manager 2512, for example, may record the new dimensions for that particular item. The rejected item may be released back into the storage and retrieval system and the replenishment transactions may be updated accordingly to account for the newly determined case dimensions.

0122The inspection station 3010 may be configured to notify, for example, the inventory manager 2512 of each item that passes inspection as the case units are transported to the in-feed transfer stations 170. The inventory manager 2512 assigns a unique identification number to each of the case units, which is used to track the respective item within the storage and retrieval system.

0123The case units are transferred from the in-feed transfer stations 170 to a bot 110, or in alternate embodiments a input bot transfer station 140, of a respective predetermined level 3000 of the storage structure 130 in a manner substantially opposite to that described above with respect to the pallet orders. The case units may be transferred from the multilevel vertical conveyor 150A to the respective predetermined storage location by the bots 110 in a manner substantially opposite to that described above with respect to the pallet orders.

0124Referring to <figref idref="f0002">Figs. 2</figref>, <figref idref="f0022">18</figref> and <figref idref="f0029 f0030 f0031">23-25</figref> bot traffic management for bot 110 movement through, for example, the transfer deck 130B, picking aisles 130A and at the transfer areas 295 will be described. In one exemplary embodiment, the bot traffic may be managed on each storage level by, for example, a respective one of the level managers 2608 and/or bot proxies 2680 (<figref idref="f0023">Fig. 18A</figref>). In alternate embodiments the bot traffic may be managed in any suitable manner by any suitable components of the storage and retrieval system 100. Each of the level managers 2608 may include a reservation manager 2608A that is configured to reserve picking aisles 130A and/or transfer areas 295 (or any other suitable resource available to the bot 110). Each of the level managers 2608 may also include a traffic controller 2608B. Any bot tasks that call for the bot 110 traversing, for example, the transfer deck 130B (or other suitable location) of a respective level are cleared for execution by the traffic controller 2608B. The bots 110 are configured to move autonomously on, for example, the transfer deck 130B such that a predetermined speed and separation distance from other bots 110 on the transfer deck 130B are maintained.

0125In operation, when a bot 110 is to enter a picking aisle 130A, the bot acquires a reservation for the picking aisle 130A. In one exemplary embodiment, a reservation for a picking aisle by one bot 110 (e.g. the reserving bot) may exclude other bots from operating in that picking aisle during the time reserving bot is traversing the reserved aisle. In another exemplary embodiment, multiple bots 110 may be allowed to reserve at least a portion of the same an aisle so that multiple bots operate within the same aisle simultaneously. Reservations for bot travel in aisles of the transfer areas 295 may be substantially similar to those for the picking aisles 130A. It is noted that the reservations may be granted based on a time an item to be picked is due at, for example, a respective multilevel vertical conveyor such that bots picking case units with an earlier delivery time are given priority when reservations are granted.

0126In accordance with an exemplary embodiment, conflicts between reservations are substantially avoided in any suitable manner. For exemplary purposes only, bot traffic and corresponding reservations may be managed on a level by level basis so that operations on one level do not interfere with operations on another different level of the storage structure 130. Travel time on the transfer deck 130B by bots 110 may be restricted to a predetermined time period (e.g. the time it takes the bot to travel from an entrance point to the reserved exit point) to avoid excess travel and congestion of the transfer deck 130B. Conflicts between reservations for transfer area 295 aisles and picking aisles 130A may be substantially avoided by having a greater number of picking aisles 130A and transfer area aisles on a level than a number of bots 110 on that level. Bots that cannot reserve a desired aisle may be provided with a different picking or replenishing job where if there are no other jobs available the bot may be sent to a vacant aisle so that it does not occupy an aisle reserved by another different bot or the transfer deck 130B.

0127Travel by bots 110 on the transfer deck may be organized so that bots 110 substantially do not enter a transfer deck 130B without having a reservation for a picking or transfer aisle where the bot 110 will exit the deck (e.g. so bots do not get trapped on the transfer deck without an exit point). Travel on the transfer deck may also be organized so that bots travel in the same direction while on the transfer deck 130B in a manner substantially similar to that of a revolving door. For example, the bots 110 traversing each segment of the transfer deck 130B travel around that segment at a predetermined speed and once a bot has an exit reservation the bot is assigned the next available corresponding segment of the transfer deck 130B for fulfilling that exit reservation.

0128In accordance with an exemplary embodiment, after a bot 110 picks an item(s) from a storage shelf 600, the bot 110 travels to the end of the picking aisle 130A and waits for clearance to enter the transfer deck 130B. The bot 110 may send a message to, for example the control server 120 requesting access to the transfer deck 130B. The control server 120, may be configured to track the location of the bots 110 on each respective level, through for example, wireless communications from the bots 110 as the bots 110 track their respective locations as described above with respect to, for example, <figref idref="f0017">Fig. 13</figref>. The bots 110 location may be, for example continuously updated in any suitable database, such as for example, the mapping database 2603. In alternate embodiments, the position of each bot 110 may be tracked and recorded in any suitable manner. The control server 120 may use the bot location to determine a time slot for allowing the bot 110 to enter the transfer deck 130B while allowing the bots 110 previously traveling on the transfer deck 110 to operate at a predetermined speed without substantial slowing. The control server 120 may send a message to the bot 110 indicating the time slot for entering the transfer deck 130B.

0129As seen in <figref idref="f0030">Figs. 24A and 24B</figref>, bots 110 entering the transfer deck 130B establish any suitable communications with one or more other bots 110 traveling on the transfer deck 130B. For example, bot 3210 may be travelling in front of bot 3200 on the transfer deck 130B. A communications link 3250 may be established between bots 3210, 3200 so that as the bots travel along the transfer deck 130B, bot 3210 substantially continuously sends, for example, its current position, speed, acceleration (or deceleration) and/or any other suitable information to the bot traveling behind it (e.g. bot 3200). Bot 3200 may use the information received from bot 3210 to adjust the speed of bot 3200 so that, for example, a predetermined travel distance is maintained between the bots 3210, 3200. A third bot, bot 3220 may be waiting to enter the transfer deck 130B in a predetermined time slot as described above. In this example, the bot 3220 enters the transfer deck 130B between bots 3200, 3210. Upon entering the transfer deck 130B, bot 3220 establishes communications with the bot 3200 directly behind it. The bots 3210, 3200 alter their communications so account for the entrance of bot 3220 onto the transfer deck 130B. In one example, when granting access to bot 3220 for entering the transfer deck 130B, the control server 120 may send messages to the bots 3210, 3200 already travelling on the transfer deck 130B that are affected by the entrance of bot 3220 for assigning the bots 3210, 3200 new communication endpoints (e.g. a message to bot 3210 to disconnect from bot 3200 and connect to bot 3220). In alternate embodiments, bot to bot communication may be performed in any suitable manner for allowing the bots to travel with each other on the transfer deck 130B.

0130<figref idref="f0031">Fig. 25</figref> is another example illustrating two bots 3301, 3302 in picking aisles 3310, 3311 requesting access to the transfer deck 130B, two bots 3303, 3305 travelling around the transfer deck 130B and one bot 3304 on transfer aisle 3320 waiting to enter the transfer deck 130B. In this example, bot 3302 has performed a pick and is waiting to enter the transfer deck 130B. Bot 3301 is about to perform a pick, after which it will got to point G and wait to enter the transfer deck 130B. The control server 120 may allow bot 3302 to enter the transfer deck 130B before bot 3301 because, for example, bot 3305 may be to close to bot 3301 to allow bot 3301 to enter the transfer deck 130B without disrupting the flow of bots already on the transfer deck. The control server 120 may allow bot 3301 to enter the transfer deck after bot 3305 passes position G. Similarly the control server 120 may allow bot 3304 to enter the transfer deck 130B behind bot 3305. It is noted that the control server 120 may be configured for simultaneous communication with each bot 3301-3305 to allow bots to substantially simultaneously enter and exit the transfer deck 130B. In alternate embodiments, the control server may be configured to communicate with each bot in a sequential manner. For example, the control server 120 may communicate with each bot in an order in which communications from the bots 3301-3305 are received by the control server 120.

0131In one exemplary embodiment the control server 120 may include a storage and retrieval system emulator 100A (<figref idref="f0022">Fig. 18</figref>). In one exemplary embodiment, the system emulator 100A may be accessed through, for example, a user interface terminal 2410 for any suitable purpose. In another exemplary embodiment, the system emulator 100A may be used by the control server 120 to, for exemplary purposes only, plan for the execution of any suitable stage of the order fulfillment/replenishment processes described herein. The system emulator 100A may be configured to emulate the operations of any suitable component or combination of components (e.g. bots, multilevel vertical conveyor, bot transfer stations, in-feed/out-feed transfer stations, inspection stations, etc.) of the storage and retrieval system 100.

0132In one example, the system emulator 100A may include bot emulators that emulate the actions of one or more respective bots 110. The software of the bot emulator may be substantially the same as that found in, for example, the bot control system 1220 (<figref idref="f0012">Fig. 10</figref>). There may be stub implementations to mimic bot movement in response to bot instructions (e.g. without actual movement of the respective bot) . The bot emulators may run in a placeholder bot environment and not on the actual bot. The placeholder bot environment may include a same host environment or a predefined host environment. In the same host environment, the control server 120 may initiate a predefined number of bot emulator processes on the same computers 120A, 120B (<figref idref="f0020">Fig. 16</figref>) the control server 120 is run on. In the predefined host environment the control server 120 may be configured to run the emulations on predetermined computers that act as one or more components of the control system 1220 of the bot 110 such as, for example, the on-board computer 1701 (<figref idref="f0017">Fig. 13</figref>). The predetermined computers may be connected to the control server 120 in any suitable manner such as through, for example, wired or wireless connections. The control server 120 may perform substantially the same startup sequence and network communication protocols within the emulated bot environment as it would in a real bot environment. The emulated bot setup may expose deployment issues with the bots so that the issues may be fixed before the respective physical bots 110 are deployed. Similarly, the control system 120 may include, for example, multilevel vertical conveyor emulators, bot transfer station emulators, in-feed and out-feed transfer station emulators and incoming inspection station emulators. These emulators may be configured to exercise application program interfaces with the control server, emulate time latency of respective components of the storage and retrieval system and offer a way to inject random or controlled failures into the storage and retrieval system to exercise exception handling and their effects on system throughput. In alternate embodiments, the control server 120 may be configured to emulate any portion of the storage and retrieval system 100 in any suitable manner and for any suitable purpose.