Patent ID: 12257918

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT(S)

FIG.1schematically illustrates an exemplary storage and retrieval system100in accordance with the embodiments. Although the disclosed embodiments will be described with reference to the embodiments shown in the drawings, it should be understood that the disclosed embodiments can be embodied in many alternate forms. In addition, any suitable size, shape or type of elements or materials could be used.

In accordance with the embodiments the storage and retrieval system100may 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 or items stored in trays totes or on pallets). 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. In accordance with the embodiments, shipping cases or case units (e.g. cartons, barrels, boxes, crates, jugs, totes, pallets or any other suitable device for holding case units) 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, bundles or 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 items (e.g. each pallet may hold different types of items—a pallet holds a combination of soup and cereal). In the 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 system100may be configured for installation in, for example, existing warehouse structures or adapted to new warehouse structures. In the embodiments, the storage and retrieval system may include in-feed and out-feed transfer stations170,160, multilevel vertical conveyors150A,150B, autonomous transport vehicle or robot (referred to herein as “bots”) stations140A,140B, a storage structure130, and a number of bots110. Suitable examples of storage and retrieval systems may be found in U.S. patent application Ser. No. 12/757,220, entitled “STORAGE AND RETRIEVAL SYSTEM” and filed on Apr. 9, 2010 and U.S. patent application Ser. No. 12/757,381, entitled “STORAGE AND RETRIEVAL SYSTEM” and filed on Apr. 9, 2010, and U.S. Provisional Patent Application Ser. No. 61/423,340 entitled “Warehousing Scalable Storage Structure” filed on Dec. 15, 2010 (now U.S. patent application Ser. No. 13/326,674 filed on Dec. 15, 2011), the disclosures of which are incorporated by reference herein in their entireties. The in-feed transfer stations170and out-feed transfer stations160may operate together with their respective multilevel vertical conveyors150A,150B for bi-directionally transferring case units to and from one or more levels of the storage structure130. It is noted that while the multilevel vertical conveyors150are described herein as being dedicated inbound or in-feed conveyors150A and outbound or out-feed conveyors150B, each of the conveyors150A,150B may be used for both inbound and outbound transfer of case units/items from the storage and retrieval system. The multilevel vertical conveyors150may be any suitable lifting devices for transporting case units between levels of the storage and retrieval system. Some non-limiting suitable examples of multilevel vertical conveyors can be found in, for example, U.S. Provisional Patent Application No. 61/423,298, entitled “MULTILEVEL VERTICAL CONVEYOR PLATFORM GUIDES” filed on Dec. 15, 2010, and U.S. patent application Ser. No. 12/757,354, entitled “LIFT INTERFACE FOR STORAGE AND RETRIEVAL SYSTEMS” and filed on Apr. 9, 2010 (the disclosures of which are incorporated by reference herein in their entireties) and U.S. patent application Ser. No. 12/757,220, entitled “STORAGE AND RETRIEVAL SYSTEM,” (previously incorporated by reference). For example, the multilevel vertical conveyors150A,150B may have any suitable number of support shelves250(FIG.2) for transporting the case units to a predetermined level261-264(FIG.2) of the storage and retrieval system100. The support shelves250may have slatted supports configured to allow, for example, fingers of a transfer arm110A (FIGS.2A,2B) of the bots110to pass between the slats for transferring case units101(FIG.2) to and from the conveyor. In alternate embodiments, case units may be indirectly transferred between the bots110and the multilevel vertical conveyors150A,150B as described in, for example, U.S. patent application Ser. No. 12/757,220, entitled “STORAGE AND RETRIEVAL SYSTEM,” (previously incorporated by reference). It is noted that in the embodiments transfer of case units between the bots110and multilevel vertical conveyors may occur in any suitable manner.

As may be realized, the storage and retrieval system100may include multiple in-feed and out-feed multilevel vertical conveyors150A,150B that are accessible by, for example, bots110on each level of the storage and retrieval system100so that one or more case unit(s) can be transferred from a multilevel vertical conveyor150A,150B to each storage space on a respective level and from each storage space to any one of the multilevel vertical conveyors150A,150B on a respective level. The bots110may be configured to transfer the case units between the storage spaces on storage racks600(FIG.2B) and the multilevel vertical conveyors with one pick (e.g. substantially directly between the storage spaces and the multilevel vertical conveyors). By way of further example, the designated bot110picks the case unit(s) from a shelf of a multilevel vertical conveyor, transports the case unit(s) to a predetermined storage area of the storage structure130and places the case unit(s) in the predetermined storage area (and vice versa). It is noted that while multilevel vertical conveyors are described herein in other aspects the conveyors may be any suitable conveyors or transfer/picking devices having any suitable transport path orientation.

The bots110may be configured to place case units, such as the above described retail merchandise, into picking stock in the one or more levels of the storage structure130and then selectively retrieve ordered items for shipping the ordered items to, for example, a store or other suitable location. As described above, the bots110may interface in any suitable manner with the multilevel vertical conveyors150A,150B such as through, for example, extension of a transfer arm110A (FIG.2A) of the bot (which may have fingers for interfacing with slatted support shelves of the multi-level vertical conveyors) relative to a frame of the bot. In the embodiments the bot may also interface with the multilevel vertical conveyors indirectly in any other suitable manner. Suitable examples of bots are described in U.S. patent application Ser. No. 12/757,312, entitled “AUTONOMOUS TRANSPORTS FOR STORAGE AND RETRIEVAL SYSTEMS” and filed on Apr. 9, 2010, U.S. Provisional Patent Application Ser. No. 61/423,220 entitled “BOT PAYLOAD ALIGNMENT AND SENSING” filed on Dec. 15, 2010 (now U.S. patent application Ser. No. 13/327,040 filed on Dec. 15, 2011), U.S. Provisional Patent Application Ser. No. 61/423,365 entitled “AUTOMATED BOT WITH TRANSFER ARM” filed on Dec. 15, 2010 (now U.S. patent application Ser. No. 13/326,952 filed on Dec. 15, 2011), U.S. Provisional Patent Application Ser. No. 61/423,388 entitled “AUTOMATED BOT TRANSFER ARM DRIVE SYSTEM” filed on Dec. 15, 2010 (now U.S. patent application Ser. No. 13/326,993 filed on Dec. 15, 2011), U.S. Provisional Patent Application Ser. No. 61/423,359 entitled “BOT HAVING HIGH SPEED STABILITY” filed on Dec. 15, 2010 (now U.S. Pat. No. 8,965,619 issued on Feb. 24, 2015), and U.S. Provisional Patent Application Ser. No. 61/423,206 entitled “BOT POSITION SENSING” filed on Dec. 15, 2010 (now U.S. patent application Ser. No. 13/327,035 filed on Dec. 15, 2011), the disclosures of which are incorporated by reference herein in their entireties.

The storage structure130may include multiple levels of storage rack modules600(FIG.2B) where each level includes an array of storage spaces (arrayed on the multiple levels and in multiple rows on each level), picking aisles130A formed between the rows of storage spaces, and transfer decks130B. In the embodiments, the picking aisles130A and transfer decks130B may be arranged for allowing the bots110to traverse respective levels of the storage structure130for placing case units into picking stock and to retrieve the ordered case units. As may be realized, the storage and retrieval system may be configured to allow random accessibility to the storage spaces. For example, all storage spaces in the storage structure130may be treated substantially equally when determining which storage spaces are to be used when picking and placing case units from/to the storage structure130such that any storage space of sufficient size can be used to store items. The storage structure130may also be arranged such that there is no vertical or horizontal array partitioning of the storage structure. For example, each multilevel vertical conveyor150A,150B is common to all storage spaces (e.g. the array of storage spaces) in the storage structure130such that any bot110can access each storage space and any multilevel vertical conveyor150A,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). The multilevel vertical conveyors150A,150B can also receive case units from any storage space on any level of the storage structure130(e.g. no horizontal partitioning). It is noted that in the embodiments the storage and retrieval system may be configured so that each multilevel vertical conveyor serves a predetermined area of the array of storage spaces. Suitable exemplary configurations of storage and retrieval systems can be found in, for example, U.S. patent application Ser. No. 12/757,381, entitled “STORAGE AND RETRIEVAL SYSTEM” and filed on Apr. 9, 2010, the disclosure of which is incorporated by reference herein in its entirety.

The storage structure130may also include charging stations290for replenishing, for example, a battery pack, capacitor, ultra-capacitor or other electricity storage device of the bots110as will be described in greater detail below. The charging stations290may be located at, for example, bot stations140A,140B (generally140) of the transfer deck130B so that the bots110can substantially simultaneously transfer items, for example, to and from a multilevel vertical conveyor150A,150B while being charged. The bots110and other suitable features of the storage and retrieval system100may be controlled by, for example, one or more central system control computers (e.g. control server)120through, for example, any suitable network180. The network180may 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, the system control server120may be configured to manage and coordinate the overall operation of the storage and retrieval system100and interface with, for example, a warehouse management system125, which in turn manages the warehouse facility as a whole. The control server120may be substantially similar to that described in, for example, U.S. patent application Ser. No. 12/757,337, entitled “CONTROL SYSTEM FOR STORAGE AND RETRIEVAL SYSTEMS” and filed on Apr. 9, 2010, the disclosure of which is incorporated by reference herein in its entirety.

Referring now toFIGS.2A and2B, each of the bots110in the storage and retrieval system100include one or more suitable electricity storage devices for powering the bot110. In the embodiments the one or more electricity storage devices may be one or more suitable capacitors or ultra-capacitors (referred to herein generally as capacitor110C). While the embodiments are described with respect to capacitors it should be understood that the electrical storage devices, in alternate embodiments, may be any suitable solid state, chemical, or other electricity storage system. Still, the bots may be powered by fossil fuels the replenishing of which may be substantially similar to that described herein.

To enable substantially full (about 100%) bot utility during normal operation (e.g. when the bot is actively transferring items in the storage and retrieval system) or during extended idle time, the bots on each storage level261-264of the storage and retrieval system100may recharge or replenish their power supplies, such as the one or more capacitors110C, at charging locations or stations290at the multilevel vertical conveyor150exchange areas (e.g. bot/transfer stations140). The bots may access the bot stations140by, for example, following lines or other suitable guides, such as conveyor access guide lines130C1-130C3on the transfer deck130B. For example, the transfer deck130B may have any suitable number of travel guide lines130L1-130L4and any suitable number of shunt or bypass guide lines130S1-130S7that form one or more travel paths or lanes for the bots110to traverse. For example, guide lines130L1,130L2allow travel in a first direction and guide lines130L3,130L4allow travel in a second direction substantially opposite the first direction. The shunt guide lines130S1-130S7may be oriented substantially transverse to the travel guide lines130L1-130L4but in other aspects they may have any suitable orientation relative to the travel guide lines. The shunt guide lines130S1-130S7allow bidirectional travel of the bots110for switching between travel guide lines130L1-130L4so that the bots can access, for example, the picking aisles130A or the bot stations140without traversing an entire length of the travel guide lines130L1-130L4. In the embodiments, the shunt guide lines may be aligned with the picking aisles130A1-130A7or any other suitable ingress or egress location of the storage and retrieval system allowing the bot to turn down a corresponding picking aisle while travelling along any one of the travel guide lines130L1-130L4. The shunt guide lines130S1-130S7may also be located at ends of the transfer deck130B or at any other suitable locations of the transfer deck130B. As an example, a bot110travelling along a path corresponding to guide line130L1may be instructed to transfer an item to a storage location in picking aisle130A4. However, the bot110may have already passed the shunt guide line130S4corresponding to picking aisle130A4. The bot may continue to travel along guide line130L1until it encounters the next available shunt (e.g. a shunt not being used by another bot) such as shunt guide line130S5. The bot may turn onto shunt guide line130S5and then turn onto one of the guide lines130L3,130L4so that the bot110is travelling in substantially the opposite direction towards the picking aisle130A4. The bot may continue to travel along one of the guide lines130L3,130L4until it encounters shunt guide line130S4, corresponding to picking aisle130A4, where the bot turns onto shunt guide line130S4for transitioning into or otherwise entering the picking aisle130A4guide way (such as, for example, a rail guidance system). The conveyor access guide lines130C1-130C3may be substantially similar to the shunt guide lines130S1-130S2however, in the embodiments the conveyor access guide lines may only allow unidirectional travel of the bots110through the bot station140. For example, conveyor access guide line130C1may provide an entrance path into the bot station. Conveyor access guide line130C2may provide a pathway for charging the bots110and allowing the bots to interface with the multilevel vertical conveyor shelves250. Conveyor access guide line130C3may provide an exit path into the bot station. The conveyor access guide lines130C1-130C3may also provide bidirectional travel of the bots so that the bots110can enter and/or leave the bot station using either of guide lines130C1or130C3. The conveyor access guide lines130C1,130C3may extend across the transfer deck130B so that the bots can access the bot station140from any one of the travel guide lines130L1-130L4and exit onto any one of the travel guide lines130L1-130L4from the bot station140. It is noted that while the embodiments of the transfer deck130B and bot stations140are described herein with respect to line following, the transfer deck130B and bot stations140may be configured so that the bots are guided by any suitable rail system. In one example, the bots110may enter and exit the picking aisles130A and the bot stations140with either a front end of the bot leading the direction of travel or a back end of the bot leading the direction of travel as described in for example, U.S. Provisional Patent Application Ser. No. 61/423,409 entitled “AUTONOMOUS TRANSPORT VEHICLE” filed on Dec. 15, 2010 (now U.S. patent application Ser. No. 13/326,423 filed on Dec. 15, 2011), the disclosures of which are incorporated herein by reference in their entireties.

In the embodiments, the travel guide lines130L1-130L4and shunt guide lines130S1-130S7(including guide lines130C1,130C3) are arranged so that the bots110travel in a substantially counterclockwise direction but it should be realized that the guide lines may be arranged so that the bots travel in a substantially clockwise direction. When traversing the guide lines130L1-130L4,130S1-130S7collisions between the bots110may be avoided in any suitable manner such as through bot-to-bot communications or bot location tracking and management through, for example, control server120or other suitable bot controller. A suitable example, of bot collision avoidance may be found in, for example, U.S. patent application Ser. No. 12/257,337 entitled “CONTROL SYSTEM FOR STORAGE AND RETRIEVAL SYSTEMS” and filed on Apr. 9, 2010, the disclosure of which is incorporated by reference herein in its entirety.

In the embodiments the bot station140may be in the form of a vestibule130V that extends between the transfer deck130B and the multilevel vertical conveyor150. Each vestibule130V may be configured with more than one charging station290A,290B (each of which may also serve as a transfer location for accessing a respective portion of the multilevel vertical conveyor shelf250) arranged in, for example, a linear array, along guide line130C2. In this example, there are two charging stations290A,290B corresponding with two item holding locations on the multilevel vertical conveyor shelf250. It is noted that in the embodiments there may be any suitable number of charging stations, which may correspond with a respective number of item holding locations on the multilevel vertical conveyor storage shelf250.

The charging stations290A,290B of each vestibule130V may be connected to a common power supply290P as will be described in greater detail below. The common power supply290P may power the charging stations290of multiple bot stations140. For example, the bot stations140may be disposed one above the other in a vertical array or stack so that the bots110of each pick floor level261-264travel along substantially parallel paths while in the bot stations140. The storage and retrieval system may include one or more power supplies290P each of which may be connected to the charging stations290of one or more pick floor levels261-264. Bot110ingress and egress to/from the vestibule130V of the bot station140and to the charging stations290along, for example, the guide line130C2may be synchronized with other bots110destined for, leaving, or charging at the charging stations290by an access-charge-depart protocol, hosted in any suitable controller of the storage and retrieval system, to maximize substantially full utility of all charging stations290of a given vestibule130V (e.g. to substantially avoid a case where the charging of bots110interferes with the ingress/egress process or other bots110designated to travel to the same vestibule130V). Each multilevel vertical conveyor may have any suitable controller150C, such as a programmable logic controller, for controlling the operations of the respective multilevel vertical conveyor150as well as controlling the power supply or supplies of the charging stations290disposed on the vestibules130V providing access to the shelves250of the respective multilevel vertical conveyor150.

The ingress and egress of the bots110to the vestibules130V may be managed by, for example a level manager297a portion of which may include a vestibule manager296(FIG.10). The level manager297may have any suitable organization so as to, for example, manage bot operations on one or more pick floor levels, in one or more stacks of bot stations140(e.g. bot stations140located one above the other), or in geographical regions of the storage and retrieval system. The level manager297may be in communication with the bots110in any suitable manner using any suitable communication protocol. For example the communication between the bots110and the level manager297may be a wired or wireless bidirectional and/or unidirectional communications, Linux based communications, etc. In the embodiments each pick floor level261-264may have its own respective level manager297for controlling or otherwise managing movement of the bots110on the respective level and/or, one level manager may manage more than one pick floor level261-264. The level manager297may be configured such that it tracks the location of operative bot charging stations290and communicates with a gang manager290G (FIG.2B—described below) for obtaining access to the chargers and the status of bot110charges. The vestibule manager296may manage the areas in which the charging stations290are located for determining if access is available before, for example, the gang manager290G requests access to the charging stations. As will be described below, if one or more charging station290in a vestibule is inoperative the vestibule manager296may, in the embodiments, close the vestibule (e.g. deny access so that bots are directed to other vestibules) with the inoperative charging station(s)290.

Each bot110, through any suitable onboard controller or manager, may communicate with the level manager to effect a charge cycle on the bot110in combination with a case unit101exchange with a multilevel vertical conveyor150on the pick floor level261-264on which the bot110is located. Each charging station290A,290B includes contacts290C for interfacing with corresponding contacts110D (e.g. such as a charger pad) on the bot110for charging, for example, the bot's capacitor(s)110C. The contacts290C may be any suitable contacts such as spring loaded or other actuable contacts that are configured to engage the contacts110D of the bot110when the bot is positioned substantially over the charging station290A,290B. These charging station contacts290C may be positioned at the charging stations290A,290B such that they interface with the contacts110D of a bot110when the bot110is positioned for interface and exchange with one of the holding locations of the multilevel vertical conveyor shelf250. As described above the bots access the vestibules130V of the bot stations140through an access-charge-depart protocol that may include getting permission to travel on to the charger contacts290C (prior to item exchange with the multilevel vertical conveyor), initiating charge, and getting permission to leave (after item exchange with the multilevel vertical conveyor). The level manager297may be configured to manage the requests for access to the vestibules130V and charging stations290A,290B and make decisions on whether to allow bots110to enter, leave and initiate/terminate charging accordingly. A charge can be initiated once the bot110has gained access and stops on one of the charging stations290A,290B corresponding to a location on the shelf250the bot110is to pick/place an item. The charging of the bot110may occur during the time it takes to transfer an item between the bot110and the shelf250or after the transfer has completed. In addition, the bot110may charge at the nearest available (e.g. unallocated) vestibule130V without interfering with other transfers (non-determinative, opportunity charging).

In the embodiments, the bots110may perform a quick charge before leaving the multilevel vertical conveyor vestibule130V, at which point the multilevel vertical conveyor controller150C may inform a gang manager290G (FIG.2B) that a quick charge has been achieved. The quick charge of the bot110may be a charge that terminates (or signals ready for termination) at the point where the power supply290P switches from a constant current mode (e.g. the power supply is delivering maximum current output with variable voltage) to a constant voltage mode (e.g. where the power supply has reached the maximum voltage output set point with a variable current). It is noted that the bot110may remain at the charging station290A,290B and continue to charge (e.g. to achieve a top off or full charge) until, for example the control server120or other suitable controller of the storage and retrieval system deems necessary to move the bot110, such as to allow another bot110access to the charging stations290A,290B.

During a quick charge the capacitor110C of the bot110may be at a voltage that does not take into account losses from the power supply290P to the capacitor110C. During a top off or full charge the extended period for the capacitor to reach the applied voltage level (Tau=R*C, 5*Tau≈99.3% of final voltage, where R is the combined ESR of the capacitor and any resistance between the power supply sense lines (FIG.3) and the capacitor). The gang manager290G may be a collection of cooperating interfaces that manages gang charging of bots110(e.g. charging more than one bot at a time where a gang is a group of bots that are charged by the same power supply) on multiple pick floor levels261-264that share a power supply. In the embodiments there may be one gang manager290G per power supply290or each gang manager may serve multiple power supplies. In the embodiments, the bots110may not have access to a charging station290if the power supply290P is enabled and operational (e.g. power is being transferred to the charging station waiting to be accessed). In the embodiments, after charging and the power supply290P stops transmitting power to the charging station290the gang manager290G, for example, may cause the bot110to remain at the charging station290for a predetermined amount of time, which in one example, may be about 280 milliseconds. In other examples, the amount of time the bot110remains at the charging station290after the power is turned off may be any suitable time period.

Referring toFIGS.3and4, there may be, for example, four charging stations290A,290B,290A2,290B2per power supply290P. The charging stations290A,290B,290A2,290B2may be vertically placed within a single multilevel vertical conveyor150area and disposed in a rectangular configuration with two charging stations290A,290B on one pick floor level and two charging stations290A2,290B2on another different pick floor level, where the pick floor levels may be adjacent to one another. As an example, referring back toFIG.2A, in this power supply configuration the charging stations of pick floor levels261,262would share a power supply, the charging stations of pick floor levels263,264would share a power supply, etc. It is noted that in the embodiments there may be any suitable number of charging stations on each pick floor level that share a power supply with any suitable number of charging stations from one or more other pick floor levels. Each power supply290P may be located within a predetermined distance to the charging stations290that it serves. For example, power supply290P may be located less than about 18 feet from the charging stations290A,290B,290A2,290B2to, for example, reduce wiring loss and increase charging throughput. It is noted that in the embodiments, the power supplies290P may be located any suitable distance from their respective charging stations290.

As described above, each power supply may be controlled by, for example, a controller150C of a respective multilevel vertical conveyor150, or any other suitable controller. In the embodiments there can be up to about sixteen power supplies290and up to about sixty-four charging stations290associated with a single multilevel vertical conveyor150where the charging stations are located on different pick floor levels. In the embodiments, the controller150C may be configured such that when the multilevel vertical conveyor is stopped (e.g. power is shut off to the conveyor) the charging stations290will remain operational. Power to the charging stations290and the multilevel vertical conveyor may be individually disabled/enabled.

Referring toFIGS.2B and3, and with respect to pick floor level262for exemplary purposes, the bot charging process may initiated before the bot110enters the multilevel vertical conveyor area (e.g. the bot station140). The bot may initiate communication with the gang manager290G to request permission to drive on to a particular charging station290A,290B. In the embodiments, the decision on which charging station290A,290B the bot is to interface with may be dependent on which multilevel vertical conveyor shelf250is the intended target and in which location of the shelf250the item to be transferred is to be picked from or placed to.

The Bot may remain out of the charging station290A,290B area (e.g. the load/unload area of the multilevel vertical conveyor) until it receives permission from, for example, the control server120(or other suitable controller such as the vestibule manager of the level manager) that it is safe to enter the charging station290A,290B. In one example, the gang manager290G may have knowledge of any other bots110on the pick floor level (which in this example is pick floor262) that may access the charging station290A,290B and may command controller150C to turn off the power supply290P for allowing a bot110to enter the charging station290A,290B. In one example, the gang manager290G may have the discretion to decide when to turn off the power supply290P and when to allow the bot110on to the charging station290A,290B.

Once the Bot has permission to move in to the charging station290A,290B (e.g. the multilevel vertical conveyor load/unload area), the bot110may maneuver to the intended charging station290A,290B and report its position accordingly. Once the bot110is located at the intended charging station290A,290B, the gang manager290G may communicate to the controller150C to re-enable the power supply290P, at which point the bot110will begin charging. This charging of the bot110may overlap with charging of other bots110that are on the same shared charging system network (e.g. if bot110is charging at charging station290A, other bots110may be also be charging at one or more of charging stations290B,290A2,290B2). In the embodiments, the charging process is open ended and may not terminate until commanded to do so by, for example, the gang manager290G or other suitable controller of the storage and retrieval system100.

The controller150C may control the power supply290P and monitor a status of the power supply290P. The controller150may monitor the status of the power supply290P and report to, for example, the gang manager290G when the power supply290P has reached a constant voltage mode and measures a current output falling below about 75% of its maximum value. It is noted that in the embodiments, the controller150C may report to, for example, the gang manager290G at any suitable time such as when the current output is above or below about 75%. At this point, the bot110has been “Quick Charged” and can be ready to perform tasks as needed. The gang manager290G may send a command to terminate the charge cycle if the bot110is needed to transport items within the storage and retrieval system100. If the Bot is not needed, charging may continue and the charger supply may remain on indefinitely. It is noted that in the embodiments the power to the charging station being used may be shut off upon a predetermined condition such as when, for example, the bot reaches a “full charge.” A full charge may be accomplished if the Bot remains charging for about five R*C time constants. The time to reach a full charge may be dependent on, for example, such factors including the resistance between the charger station contact290C and the contacts110D of the bot110, the wiring on the bot110as well as the resistance inside the capacitor110C. In one example, a bot110may leave the charging station290A,290B any time after a quick charge.

In the embodiments there may be N number of gang managers290G controlling N number of power supplies290P. For example, the controller150C of each multilevel vertical conveyor150may have addressable ports unique to each power supply290P. The bot110when requesting a charge may communicate, through for example, level manager297(FIG.2B), with a gang manager290G controlling a power supply290P for a charging station to which the bot110will travel. As described above, the communication between the bots110and the level manager297as well as the gang manager290G, controller150C and power supply290P (and other suitable components of the storage and retrieval system) may be any suitable communication protocol and methods such as, for example, wired or wireless bidirectional and/or unidirectional communications, Linux based communications, or other suitable communications.

Referring toFIG.6, in the embodiments the level manager297may manage the bots110on a level (or more than one level) to which the level manager297is assigned. The level manager297may include a bot controller298for use by the bots110, and conversely each bot110may include a controller118for use by the bot controller298. There may be, for example, a one to one mapping between the bot controller298and each bot110(e.g. the level manager297includes one bot controller for each bot) or, one bot controller may be mapped to more than one bot. The level manager297may also include a charge manager299that may act as an intermediary between the bot controller298and the gang manager290G to manage charging.

Each bot controller298may communicate with the gang manager290G via the charge manager299to effect charging of the bot110. In the embodiments there may be, for example, ten multilevel vertical conveyors that intersect the pick floor levels261-264(e.g. with twenty charging stations290disposed at each pick floor level—e.g. two charging stations per multilevel vertical conveyor intersection). It is noted that in the embodiments there may be any suitable number of multilevel vertical conveyors and charging stations per pick floor level. The charge manager299may choose the appropriate charging station290to converse with for a given charge cycle. Since bot gangs (e.g. groups of bots charged using the same power supply) span adjacent levels, two level managers297may each establish communication connections with the charging stations290of their respective levels (which in this example, is twenty charging stations per level).

Conversely, each charge manager299may include a charging station status server299S for each charging station290, that the gang manager290G uses to relay power supply status information sent to it by a charging communication service620. It is noted that the charging communication service620may handle status requests from, for example, the controller150C, on/off requests for, as an example, controller150C, and requests to enter/leave a charging station290. Since each gang manager290G may manage two pick floor levels, it may have connections to, for exemplary purposes only, about four such charging station status server objects, e.g. two for each pick floor level. There may be as many named instances for requests to enter/leave a charging station290(e.g. a request instance) as there are charger stations290. In one example, each group of four request instances maps to a portion of the charging communication service that handles on/off requests, and hosts a portion of the charging communication service that handles charging station status requests.

In an exemplary operation, the bot controller298may issue tasks for the bot110. It is noted that when issuing tasks for the110, the bot controller298may allow for an efficient exchange of items between the bots110and the multilevel vertical conveyors. When issuing these tasks the bot controller298may do so such that bots110are not held up from entering the bot stations140(and charging areas290) for commencing item transfer with the multilevel vertical conveyor150. Also, when issuing tasks the bot controller may not prevent egress of bots from the charging areas290because of bots110that have not finished charging or have not received a minimum amount of charge. It is also noted that if a first bot110has not completed a case unit101transfer with the multilevel vertical conveyor150any bots located in charging stations290behind the first bot110may remain in their charging stations to continue receiving a charge.

Referring toFIG.7, when issuing tasks the bot controller may be aware of when the bot110needs to enter the charging station290, and when the bot110is at the charging station290. However, the bot controller298may not be aware of exactly when in time the bot110clears or leaves the charging station290. The bot controller298and the bot110may cooperate with each other to create a charging cycle. In an exemplary charging cycle, the bot controller may identify the appropriate charging station290to communicate with. The bot controller298may request (e.g. a “can bot enter” message) that the charge manager299send a “bot can enter” message to the charging station290. The gang manager290G may verify that the charging station290is turned off and waiting for a charger status to reflect the off status. The gang manager290G may send a charger status and “bot can enter” message to the charge manager299, which relays it to the bot controller298. The bot controller298may issue other tasks to the bot110via the controller118. When the bot110reaches the charging station290, the bot controller298may wait for a “bot is at charging station” message in order to read a simulated bot voltage and ask the charge manager299to send a “bot is at charging station” message to, for example the gang manager290G. The charge manager may send a “bot has quick charge” message when the bot110has received a quick charge. This allows the level manager297to mark the bot110as available for other tasks, when it finishes any current job, such as the transfer of items between the bot110and the multilevel vertical conveyor. When the bot controller298deems that the bot110should move out of the charging station290, it asks the charge manager to send a “can bot leave” message, to for example, the gang manager290G. The gang manager290G verifies that at least a quick charge has been delivered to the bot110, turns off the charging station290if necessary, and sends a “bot can leave” message, which gets relayed to the bot controller298and then to the controller118. This allows the simulated bot to update its voltage at the end of a charge cycle. It is noted that the simulate bot may exist in the any suitable memory of any suitable controller of the storage and retrieval system such that based on the tasks sent to the bot, the controller can determine how much of a charge remains in the bot. It is noted that in the embodiments, the bots110may periodically send a message to the controller indicating a charge status of the bots110or that the bots110need to be charged. The bot controller298may send the next set of tasks to the bot110. When the bot110deems that it is safely out of the charging area, the bot110may send a “bot has left” message, which causes the bot controller298to send a “bot has left” message via the charge manager299. The bot110need not wait for an acknowledgement or stop its motion to send this message. The power supply290P gets re-enabled by the gang manager290G if necessary for other bots remaining at the charger stations290.

In the embodiments, separately from any ongoing charge cycle interactions, the gang manager290G may relay power supply status information to, for example, the level manager297so that the level manager may route bots110away from unavailable chargers. It is noted that the level manager297may establish, through for example, the gang manager290G the operational status of each of the charging stations290and whether the charging stations290are available.

It is noted that each bot goes through the same charging sequence described above. In the embodiments, the gang manager290G may be configured to reconcile multiple pending charge requests by turning each of the charging stations on and off, individually or in groups, as needed. The gang manager may also be configured to collectively turn off the charging stations by, for example, turning off the power supply290P. This is done by keeping track of the number of bots110moving to/from the charging stations290, and the number of bots at the charging stations290. One non-limiting example, of keeping tracking of bots110is as follows:

RequestActionsCan Bot EnterIf necessary, the charger is turned OFFWhen the charger is confirmed to be OFF:iNumMoving++Send botCanEnterBot Is At ContactiNumMoving−iNumAt++if(!iNumMoving && iNumAt)turn_charger_on ( )Can Bot LeaveIf bot has not received one charge cycle,defer request until such charge is receivedor power supply fails or is disabled.Charger is turned OFF if necessaryWhen the charger is confirmed to be OFF:iNumMoving++Send botCanLeaveBot Has LeftiNumMoving−if(!iNumMoving && iNumAt) turnChargerOn ( )Charger StatusIf charger passed the quick charge mark, markall bots at charger to have received a quickcharge so they can leave if desired. Send thebot HasQuickCharge ( ) message.If charger turned off as a result of havingbeen turned off, update all bot states asoutlined previously so bots can enter orleave the charger contact.If the charger had an error, sendnotification on appropriateChargerContactStatus::isAvailable ( )interfaces.

The term “Comm Failure” may be used to indicate that the two sides of a communication connection get an “unbind” indication. Conversely, the “bind” indication indicates a (re)connection between the two sides. The following outlines non-limiting exemplary charging specific actions that may be done upon various failures.

ActivityValueRationaleComm messageAbout 1Expected worst case time fortransactionseconda comm message to reachtimedestinationMaximum powerAbout 46.3 VPower supply specificationsupply cutoffvoltagePower supplyAbout 2Hardware behaviourturn off timesecondsPower supplyAbout 110 APower supply field configurationmaximum currentHighest botAbout 181.5 F.The supercap used on the bots iscapacitancenominally about 165 F., allow 10%variationMaximum chargeAbout 305Largest voltage delta to quicktime for a botsecondscharge = MaxPowerSupplyCutoff −0 V = about 46.3 VSmallest current while charging =Power supply minimum current/MaxContactsPerSupply =111/4 = about 27.25 AWorst case time to charge =max_capacitance * max_delta_V/min_current = 181.5 * 46.3/27.25 = about 303 secondsAdditional about 2 seconds to turnoff supply at end.Time for bot toX secondsAllowance for botmove to contactafter havingreceivedpermissionto do soTime for bot toY secondsAllowance for botmove away fromcontact afterhaving receivedpermission todo soOverall marginAbout 10%,Additional margin for all timeoutminimum,calculationsabout 1second

The following are non-limiting exemplary timeout values that may be used to deem a transaction to be a failure.

Time outEntity usingTransaction(sec)timeoutRationalecanBotEnter −>About 7ChargeAbout 4 commbotCanEnterManagertransactions turnoff power supplybotCanEnter −>About 8Gang ManagerAbout 2 commbotIsAtConttransactionsactmove botbotIsAtCont act −>About 338ChargeAbout 2 commbotHasQuickManagertransactions toChargegang managerMax charge time =N secondscanBotLeave −>About 7ChargeAbout 4 commbotCanLeaveManagertransactions turncharger offbotCanLeave −>About 6Gang ManagerMove botbotHasLeftTime toAbout 5Gang Manageroff cycleturn off aAbout 1 each forbotcommTime toAbout 338Gang ManagerAbout 2 commcharge atransactions maxbotcharge time =N seconds

When there is a power supply failure a message may be relayed from the gang manager290G. During a power supply failure the bots110may be allowed to leave the charging stations290even if the bots have not received a minimum amount of charge. The charge manager299may use the information from the gang manager290G in conjunction with, for example, the state of the bot110or bot controller's298conversation with the gang manager290G to complete any pending charging cycles, and mark the charging station(s)290connected to the failed power supply as inoperable. In this case the gang manager290G and or charger manager299may find other available charging stations290and communicate with the level manager297for routing the bots110that did not receive the minimum amount of charge to these available charging stations290(e.g. without impeding ingress/egress to the respective multilevel vertical conveyors150at the locations of the available charging stations290.

With respect to other exemplary communications within the bot charging system, the bots110may communicate with a respective bot controller298to indicate a simulated bot's voltage and that the bot has left (or arrived at) a charging station290. The bot controller298may communicate with a respective bot110a post-charge voltage that may be valid only during a simulation. The charge manager299may communicate with the charging stations290to ensure the charging station is off so a bot110can enter or leave the charging station290. The charge manager299may also indicate when gang charging can start or resume, indicate that a bot has left a charging station and to resume charging and to enable/disable one or more charging stations. The gang manager290G may indicate the charging station is off so that the bot can move on to or off the charging station, that the bot has received a quick charge, and a state of the charging station290(e.g. whether the charging station is inoperable, off, in constant current mode, in constant voltage mode, etc.).

In the embodiments, the bot controller298may be configured to allocate the charging stations290using reservations (e.g. each bot that is to access a particular charging station “reserves” or allocates that charging station so no other bots are able to access it during the reservation period). When a bot110with a reservation accesses a charging station290it receives a charge and when complete the bot110requests to release (e.g. un-reserve) the charging station290so that the charging station290can be reserved for other bots110.FIG.8illustrates a transaction state diagram for a charging sequence in which a reservation is held. For example, before the bot enters the charging station290a request is made for the bot to enter the charging station. If there is no bot present at the charging station290the request may be granted and the bot enters the charging station290. If only a transfer of items to/from a multilevel vertical conveyor150is being made, the transfer may take place and a request for release of the charging station290may be sent by the bot110and after the release a notification that the bot110has left may be made. Where charging is to occur (in addition to or in lieu of a transfer of items to/from the multilevel vertical conveyor150) charging may occur when the bot110is in the charging station290. A check may be made as to whether the bot110has received a quick charge. If the bot110has received a quick charge the bot110is able to leave the charging station290and makes a request to release the charging station290. Once the charging station290is released the bot110exits the charging station290and an indication that the bot110has left is made.

FIG.9illustrates exemplary class hierarchies and dependencies with respect to communication between the charge manager299and the bots110.

In the embodiments the operational state of the charging station within a vestibule130V may be linked in any suitable manner to an operational state of a corresponding multilevel vertical conveyor150. Referring toFIG.10, for exemplary purposes only four vestibules130V1-130V4of a single pick floor level are shown where each vestibule130V1-130V4has two charging stations290. It is noted that in the embodiments the storage and retrieval system may have any suitable number of vestibules each having any suitable number of charging stations. Each vestibule is served by a respective multilevel vertical conveyor150-1,150-2,150-3,150-4. Each of these multilevel vertical conveyors also serves other vestibules vertically stacked above and/or below a respective one of the vestibules130V1-130V4.

Upon startup of the level manager297, with respect to charging operations of the bots110, the charge manager299knows the structural information about each charging station290(e.g. where they are located and which multilevel vertical conveyor is associated with the respective charging stations). The charge manager299may communicate with each charging station290to obtain, for example, an operational status of the charging stations290. The bot controller298of the level manager297may communicate with the bots110for issuing commands or jobs (e.g. to transfer case units101) to the bots110.

When a bot, such as bot110X, needs to be charged, whether in conjunction with the transfer of a case unit101to/from a multilevel vertical conveyor150-1,150-2,150-3,150-4or not, the bot may send a message to a vestibule manager296for determining which vestibule130V1-130V4the bot is to be directed to. In the embodiments the vestibule manager296may be part of the level manager297or, the vestibule manager296may be included in any suitable controller of the storage and retrieval system. If the charging of bot110X is not in connection with a case unit101transfer, the vestibule manager296may direct the bot110X to a vacant or unallocated operational charging station290in a nearest “online” or operational vestibule130V1-130V4. If the charge of the bot110X is in conjunction with a transfer of case units101to/from a multilevel vertical conveyor150-1,150-2,150-3,150-4, the vestibule manager296may communicate with the vestibule (which for exemplary purposes may be vestibule150-3) at which the bot110X is to transfer the case units101to verify that the charging stations290of that vestibule are operational. At least one of the charging stations at, for example, vestibule150-3may be reserved for the bot110X as described above. If however, one or more of the charging stations for the vestibule150-3is determined as being inoperable a suitable controller of the storage and retrieval system such as control server120may inform the level manager297and/or the vestibule manager296that the vestibule150-3is “offline” or inoperable such that no case units101can be transferred to the multilevel vertical conveyor150-3nor can bots110be charged at other operational charging stations290of offline vestibule130V3. The level manager297, with information provided by the vestibule manager296, may communicate with bot110X and direct the bot110X to an available charging station290of the next available vestibule130V1-130V4for transferring the item101while simultaneously charging the bot110X.

In the embodiments, vestibules vertically stacked above and/or below vestibule130V3may still be able to charge bots110and transfer case units101to the multilevel vertical conveyor150-3. In the embodiments, because the charging stations290of vestibule130V3may be powered by the same power supply290P (FIG.3) as charging stations of vestibules stacked above and/or below vestibule130V3, all of the vestibules associated with the power supply of vestibule130V3may be designated as offline for charging and item101transfers. Still, the vestibule130V3may remain “online” so that bots can charge and transfer case units101at the remaining operational charging station(s)290of the vestibule130V3. The vestibule130V3may also remain online with respect to item transfers such that, if bot110X has a sufficient charge, the bot110X can transfer items at a location of the inoperable charging station290and then move on to be charged at a next available charging station290at the same vestibule130V3or different vestibule130V1,130V2,130V4.

Referring toFIGS.11-13and also toFIGS.2B and6the bot controller298and charge manager299may interact with each other for reserving resources within the storage and retrieval system100. It is noted thatFIG.12illustrates a state chart diagram for bot controller298interaction for reserving resources of the storage and retrieval system andFIG.13illustrates a sequence diagram of how each reservation request for a charging station translates into a reservation of the charging station. As an example, bot110X may be designated by bot controller298for charging at charging station290B of vestibule130V. Travel of the bot110X may be defined by waypoints1101-1108within the storage and retrieval system100. As the bot travels the bot controller298of level manager297may look to each waypoint for reserving a resource of the storage and retrieval system to allow the bot110X to travel along a predetermined course. Prior to or during reservation of the resources by the bot controller298the charge manager may confirm that a desired charging resource and any intervening charging resources are available or will be available at the time they are needed by the bot110X. If the charging resources are available the bot controller298continues with planning the predetermined route, which in this example, is charging station290B. If one or more of the charging resources and intervening charging resources are not or will not be available the route of the bot110X may be re-routed to an available charging resource (and corresponding multilevel vertical conveyor). In this example, the bot110X may start in picking aisle130A7for picking a case unit101. Picking aisle103A7may be reserved by the bot110X while the bot110is located within the aisle130A7. As the bot is travelling out of the picking aisle130A7a request to reserve an entrance onto guide line or travel path130L4is made and granted. Once on the guide line130L4a reservation is requested for travelling along vestibule130V/multilevel vertical conveyor150entrance guide line or path130C1and is granted. The bot controller looks to the next waypoint1107and requests a reservation for the multilevel vertical conveyor transfer location290T1and if the availability of the transfer location290T1is verified the request is granted. The bot controller may check to see of the transfer location290T1is also a charging resource, which it is, and requests a reservation for charging station290A and if the charging station is available the request is granted. Even though the bot110X will not transfer case units101or charge at transfer location290T1/charging station290A, the bot110X passes through these areas on its way to charging station290B and reserves transfer location290T1/charging station290A to ensure passage to charging station290B. The bot controller also looks to waypoint1108to reserve multilevel vertical conveyor transfer location290T2and if the availability of the transfer location290T2is verified the request is granted. The bot controller298may check to see of the transfer location290T2is also a charging resource, which it is, and requests a reservation for charging station290B and if the charging station is available the request is granted. After the bot passes through transfer location290T1and charging station290A the bot controller releases transfer location290T1and charging station290A so these resources are available to other bots110. While the bot110X is at the transfer location290T2, the bot110X may transfer case units101between the bot110X and the conveyor shelf250while simultaneously receiving a charge from charging station290B. Upon reaching a quick charge level the bot110X the bot controller298is notified of the quick charge being substantially complete and requests that the bot110X leave the transfer location290T2and charging station290B. The bot110X verifies that it has left the transfer location290T2and charging station290B and the bot controller releases the transfer location290T2and charging station290B so they become available resources for other bots110.

Referring again toFIGS.6and10, as described above, when a charging station290becomes inoperable the storage and retrieval system is configured to re-route a bot110to another operable charging station290. In one exemplary embodiment when a charging station290becomes inoperable all affected bot controllers298are notified for taking appropriate action such as, for example, canceling jobs directed to the inoperable charging station. It is noted that in one exemplary embodiment the affected bot controller298may be bot controller for pick floor levels having charging stations powered by the same power supply as the inoperable charging station. Any bot jobs not yet scheduled (e.g. that have already been re-routed) may not be allocated to the inoperable charging stations290or their corresponding multilevel vertical conveyors150for at least the pick floor level on which the inoperable charging station290is located.

Referring again toFIG.2Bin the embodiments the controller150C may be used to initiate and monitor charging of the bots110. In one example the gang manager290G may start the power supply290P and the controller150C may enable the power supply output. The controller150C may monitor an operational status of the power supply and alert the gang manager290G if there is any inoperability of the power supply290P. The controller150C may wait a predetermined amount of time before monitoring the power supply290P (e.g. to avoid any inrush power spikes) and maintain a record of the current of the power supply and monitors the current for a condition where the current drops below a predetermined level. The gang manager290G may turn off the power supply for any suitable reason (such as e.g. when a bot wants to enter or leave a charging station) and the controller150C may turn off the power to the chargers and direct the bots110accordingly.

In a first aspect of the embodiments, a charging system for autonomous transport vehicles in a warehouse storage and retrieval system is provided. The charging system includes at least one charging contact disposed on each pick floor level of the storage and retrieval system, each of the at least one charging contact being located at a transfer station, at least one power supply configured to supply power to the at least one charging contact and a first controller in communication with the transfer station and being configured to communicate information relating to a transfer of items between the transfer station and a predetermined one of the autonomous transport vehicles and to apply power from the power supply to the at least one charging contact for charging the predetermined autonomous transport vehicle corresponding to the transfer and located at the multilevel vertical conveyor transfer station, wherein the first controller is configured to supply power to the charging contacts for charging the predetermined autonomous transport vehicle simultaneously with the predetermined autonomous transport vehicle exchanging items at the transfer station.

In accordance with a first sub-aspect of the first aspect of the embodiments, the charging system further comprising a capacitor disposed on the autonomous transport vehicle and a receptacle configured to interface with the at least one charging contact where the engagement is configured to transfer power to the capacitor.

In accordance with the first sub-aspect of the first aspect of the embodiments, the receptacle includes a contact pad and the at least one charging contact includes actuable members configured to engage the contact pad.

In accordance with the first aspect of the embodiments, each pick floor of the storage and retrieval system includes at least one vestibule extending from a transfer deck and located adjacent a respective multilevel vertical conveyor, wherein at least one charging contact is located in each of the at least one vestibule.

In accordance with the first aspect of the embodiments, the transfer station includes a multilevel vertical conveyors and the operation of the at least one charging contact and an associated multilevel vertical conveyor are linked such that when the at least one charging contact is inoperable the controller deems the multilevel vertical conveyor inoperable at least for the pick floor level on which the at least one charging contact is located.

In accordance with the first aspect of the embodiments, the first controller is configured to control operations of the power supply and the multilevel vertical conveyor.

In accordance with a second sub-aspect of the first aspect of the embodiments, the charging system further comprises a second controller configured to effect a charge cycle of each autonomous transport vehicle located on at least one pick floor level simultaneously with the exchange of items with the multilevel vertical conveyor.

In accordance with a second aspect of the embodiments, a storage and retrieval system is provided. The storage and retrieval system includes, at least one autonomous transport vehicle, at least one transfer station having an operable and inoperable state where in the operable state the at least one transfer station is configured to allow transfer of items from and to the at least one autonomous transport vehicle, at least one charging station disposed on each pick floor level of the storage and retrieval system, each of the at least one charging contact being located at a respective one of the at least one transfer station, at least one power supply configured to supply power to the at least one charging contact, and a controller in communication with the transfer station and being configured to communicate information relating to a transfer of items between the transfer station and a predetermined one of the autonomous transport vehicles and to apply power from the power supply to the at least one charging station for charging the at least one autonomous transport vehicle located at the transfer station, wherein the controller is configured to supply power to the charging station for charging a predetermined autonomous transport vehicle corresponding to the transfer of items simultaneously with the predetermined autonomous transport vehicle exchanging items related to the transfer at a predetermined transfer station when the predetermined transfer station is in the operative state and to supply power to the charging station for charging another of the at least one autonomous vehicles located at the predetermined transfer station when the predetermined transfer station is in the inoperative state.

In accordance with the second aspect of the embodiments, the storage and retrieval system further includes at least one multilevel conveyor and at least one pick floor level having storage locations, at least one vestibule and a transfer deck connecting the storage locations with the at least one vestibule, each of the at least one vestibules having at least one of the at least one transfer station configured to provide access to a respective one of the at least one multilevel vertical conveyor, wherein the controller is configured to control operations of at least one of the at least one multilevel vertical conveyors and operations of at least one charging station located in vestibules associated with the respective multilevel vertical conveyor.

In accordance with the second aspect of the embodiments, a level controller is connected to each pick floor level and configured to control storage and retrieval operations of the respective level, the level controller being further configured to link operations of the at least one multilevel vertical conveyors with associated charging stations such that access to the at least one multilevel vertical conveyor is prevented when one or more of the associated charging stations is inoperable.

In accordance with a first sub-aspect of the second aspect of the embodiments, the storage and retrieval system includes at least one power supply, the at least one power supply being commonly connected to charging stations of vertically adjacent ones of the at least one pick floor level.

In accordance with the first sub-aspect of the second aspect of the embodiments, the charging stations commonly connected to the at least one power supply comprising a two by two array of charging stations where a first two of the charging stations in the array are located on a first pick floor level and a second two of the charging stations in the array are located on a second pick floor level, the first two of the charging stations and the second two of the charging stations being vertically stacked one above the other.

In accordance with the first sub-aspect of the second aspect of the embodiments, each vestibule includes at least two charging stations arranged on a common linear path.

In accordance with the first sub-aspect of the second aspect of the embodiments, the transfer deck includes an array of autonomous transport vehicle travel paths, the array including longitudinal travel paths providing access to the storage locations and the at least one vestibule and transverse travel paths providing shunts between the longitudinal travel paths.

In accordance with the second sub-aspect of the second aspect of the embodiments, the controller is configured to reserve one or more of the charging stations for allowing an autonomous transport vehicle access to the one or more of the at least two charging stations.

In accordance with the second aspect of the embodiments, the controller is configured to re-route an autonomous transport vehicle destined for a charging station at a first vestibule to a charging station at another vestibule when the charging station at the first vestibule is inoperable.

In accordance with the second aspect of the embodiments, when in the unallocated state the transfer station is not configured to allow transfer of items from and to the at least one autonomous transport vehicle.

It should be understood that the embodiments disclosed herein can be used individually or in any suitable combination thereof. It should also be understood that the foregoing description is only illustrative of the embodiments. Various alternatives and modifications can be devised by those skilled in the art without departing from the embodiments. Accordingly, the present embodiments are intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.