System and conveying device therefor

Abstract

A system having a first transport apparatus (2) with one of the guide means (16, 18, 34) or the drive means (26) connected to a surface of a second transport apparatus having the other of the guide means (16, 18, 34) or the drive means (26), the drive means being configured to interact with the guide means to effect movement of one of the first or second transport apparatus relative to the other of the first or second transport apparatus, the guide means being configured to change between an active state in which it is securely engaged with the drive means to effect movement of one of the first or second transport apparatus, and a passive state in which the drive means is not engaged and allows the first and second transport apparatus to be separated.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of robotic storage systems, and more specifically to transport and storage devices arranged to form clusters having reconfigurable physical topologies. [Background technology]

[0002] Certain commercial and industrial activities require systems that allow for the storage and retrieval of a large number of items that may be stored in containers. Methods for handling containers stacked in rows have been known for decades. In some such systems, as disclosed, for example, in U.S. Patent No. 2,701,065 (Bertel), a freestanding stack of containers is arranged in rows to reduce the amount of storage associated with storing the containers while still providing access to a particular container when needed, as disclosed, for example, in U.S. Patent No. 2,701,065 (Bertel). Access to a given container is made possible by providing a relatively complex hoisting mechanism that can be used to stack and remove a given container from the stack. However, the cost of such systems makes them impractical in many situations, and they have been primarily commercialized for the storage and handling of large shipping containers.

[0003] The concept of using a freestanding stack of containers and providing a mechanism for removing and storing a particular container has been further developed, for example as disclosed in EP 0767113 (Cimcorp). In this document a mechanism for removing a stack of containers is disclosed using a robotic material handling handler in the form of a rectangular tube that is lowered around the stack of containers and configured to be able to grab a container at any height in the stack. In this way several containers can be lifted from the stack at once. The rectangular tube can be used to move several containers from the top of one stack to the top of another stack, or to move containers from a stack to an external location and vice versa. Such a system can be particularly useful where all containers in a single stack contain the same product. Such a stack is known as a single product stack. In the system disclosed in EP 0767113 the height of the tube must be at least as high as the height of the largest stack of containers so that the highest stack of containers can be extracted in a single operation. Thus, when used in enclosed spaces such as warehouses, the maximum height of the stack is limited by the need to accommodate the tubes of the robotic material handler above the stack.

[0004] One known type of system for storing and retrieving multiple product line items involves arranging storage bins or containers in stacks arranged in rows, one above the other, such that the storage bins are removed from the stack and accessed from above by a robotic material handling device, eliminating the need for aisles between the rows and allowing more containers to be stored in a given space.

[0005] European Patent No. 1037828 (Autostore) discloses a system in which a stack of containers is arranged within a frame structure. A robotic handling device can be controllably moved around the stack on a track system on the top surface of the stack. Further forms of robotic handling device are disclosed, for example, in Norwegian Patent No. 317366.

[0006] UK Patent Publication No. 2520104 (Ocado Innovation Limited) discloses a robotic load handling apparatus in which each robotic load handler covers only one grid space, allowing a higher density of robotic load handlers and therefore a higher throughput for a system of a given size, although any suitable form of load handling apparatus may be used.

[0007] However, each of the known robotic storage systems described above suffers from one or more of the following drawbacks: In all instances, a perimeter frame structure is required above / around the stack of storage bins. The frame structure supports a robotic material handling handler that traverses the top of the frame structure above the stack of storage bins. The use of such a frame structure reduces the density at which the storage bins can be stored because of the space consumed by the frame structure. Furthermore, such a frame structure is not dynamically scalable because it must be built to accommodate the maximum anticipated capacity, even if that capacity is uncertain or in the distant future.

[0008] Additionally, the robotic material handler must "dig" down through the stack of storage bins to retrieve a selected storage bin, which represents a time and energy overhead when retrieving a storage bin. Also, the above-described system requires a robotic material handler, which represents an added cost to the system.

[0009] Furthermore, when such systems are coordinated, the actual progression of a robotic load handler from a start location to a destination location typically requires the robotic load handler to take many unnecessary, unproductive and / or costly steps, such as using route planning and / or collision avoidance to avoid other robotic load handlers. Also, when a storage bin becomes stuck in a stack of storage bins, it is difficult to retrieve the storage bins below the stuck storage bin. Similarly, when a robotic load handler breaks down, access to the storage bins below the robotic load handler is limited until the robotic load handler is removed from its location above the stack of storage bins. Furthermore, when a robotic load handler breaks down, it can be difficult to recover.

[0010] It is against this background that the present invention was conceived. Summary of the Invention

[0011] Thus, in a first aspect, there is provided a system comprising one or more transport devices arranged in a cluster, the system comprising one of a guide means or a drive means connected to a surface, i.e. associated with the surface, and a first transport device adjacent to the surface and comprising the other of the guide means or drive means, the drive means being configured to interact with the guide means to effect movement of one of the first transport devices or surfaces relative to the other of the first transport devices or surfaces, the guide means being configured to change between an active state in which it is securely engaged with the drive means to effect movement of the first transport device or surface, and a passive state in which the drive means is not engaged and allows the first transport device and the surface to be separated.

[0012] Optionally, the first transport apparatus comprises the drive means and the surface comprises the guide means, the surface forming part of the second transport apparatus.

[0013] Optionally, the first transport apparatus further comprises guide means configured to interact with drive means of an adjacent transport apparatus to direct movement of the first transport apparatus or an adjacent transport apparatus within the cluster.

[0014] Optionally, the second transport apparatus further comprises a drive means for moving the second transport apparatus or an adjacent transport apparatus within the cluster.

[0015] Optionally, each conveying device of the plurality of conveying devices has a rectangular parallelepiped shape, the drive means being provided on two adjacent sides and the guide means being provided on the remaining two adjacent sides.

[0016] Optionally, each transport device of the plurality of transport devices is positioned in the cluster in the same orientation such that at least one side associated with the drive means of any one transport device having at least one proximal transport device faces a side associated with the guide means of the proximal transport device.

[0017] Optionally, the guide means comprises a retaining means for maintaining engagement between the guide means and the drive means while the guide means is in the active state.

[0018] Optionally, the guide means is configured to be held in at least one of a first position or a second position when in an active state, the first position and the second position being arranged to direct movement of the first transport device or surface across the cluster in a first direction and a second direction respectively.

[0019] Optionally, the first direction is substantially orthogonal to the second direction.

[0020] Optionally, the drive means of the first transport apparatus is arranged to rotatably engage with the guide means of the second transport apparatus.

[0021] Optionally, the guide means comprises a rack and the drive means comprises a pinion configured to engage the rack.

[0022] Optionally, the rack is movable to move the guide means between the active and passive states.

[0023] Optionally, the rack is rotatable about an axis of rotation parallel to the axis about which the pinion rotates.

[0024] Optionally, the axes of rotation of the rack and pinion are offset relative to one another.

[0025] Optionally, the axis of rotation of the rack lies at the vertices of a notional square circumscribing the circumference of the pinion.

[0026] Optionally, the rack further comprises a fixed portion extending in the first direction and in the second direction.

[0027] Optionally, the retaining means comprises two walls positioned on either side of the rack defining a channel in which the pinion is received when the guide means is in the active state.

[0028] Optionally, each transport device of the plurality of transport devices comprises vertical alignment means for aligning it with adjacent transport devices within its vertical vicinity.

[0029] Optionally, the vertical alignment means comprises a recessed area formed in the top surface and a retractable post extending from the bottom surface, the recessed area of ​​any one transport device being configured to receive the retractable post of an upper adjacent transport device to ensure vertical alignment of the transport devices.

[0030] Optionally, at least one transport device comprises a larger or smaller volume compared to other transport devices.

[0031] Optionally, each transport device is individually addressable via one or more communication units.

[0032] Optionally, each transport of the plurality of transports comprises a receiving space for holding inventory.

[0033] Optionally, the surface is fixed, for example forming part of a wall or floor.

[0034] In a second aspect, there is provided a transport apparatus for use in a system according to the first aspect.

[0035] In a third aspect, a plurality of transport devices arranged in a cluster is provided, the transport devices comprising a first transport device having a drive means and a second transport device having a guide means, the second transport device being adjacent to the first transport device, the drive means of the first transport device being configured to interact with the guide means of the second transport device to effect movement of one of the first transport device or the second transport device relative to the other of the first transport device or the second transport device, the guide means being configured to change between an active state in which it is securely engaged with the drive means of the first transport device to effect movement of the first transport device or the second transport device within the cluster, and a passive state in which the drive means of the first transport device is not engaged and allows the first transport device and the second transport device to be separated.

[0036] These and other aspects will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0037] [Figure 1] 1 is a schematic perspective view of a storage system including a plurality of transport devices arranged in a cluster according to an embodiment of the present invention; [Figure 2a] 2A-2C show schematic perspective views of a transport device in different rotational positions for use in the cluster of FIG. 1; [Figure 2b] 2A-2C show schematic perspective views of a transport device in different rotational positions for use in the cluster of FIG. 1; [Figure 2c]2A-2C show schematic perspective views of a transport device in different rotational positions for use in the cluster of FIG. 1; [Figure 2d] 2A-2C show schematic perspective views of a transport device in different rotational positions for use in the cluster of FIG. 1; [Figure 3a] 3A-3D show schematic elevational views of the drive means and guide means used in the conveying device of FIG. 2, the guide means being held in different rotational positions; [Figure 3b] 3A-3D show schematic elevational views of the drive means and guide means used in the conveying device of FIG. 2, the guide means being held in different rotational positions; [Figure 3c] 3A-3D show schematic elevational views of the drive means and guide means used in the conveying device of FIG. 2, the guide means being held in different rotational positions; [Figure 4a] FIG. 4 is a schematic diagram showing the drive means and the guide means in an engaged position; [Figure 4b] FIG. 4 is a schematic diagram showing the drive means and the guide means in an engaged position; [Figure 4c] 1 shows the drive means and the guide means in the disengaged position. [Figure 5a] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5b] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5c] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5d] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5e] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5f]3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5g] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 5h] 3 shows a series of schematic perspective views illustrating some steps involved in an example of repositioning the transport device of FIG. 2 within a cluster of transport devices; [Figure 6a] 3A-3D show a series of schematic side views of a cluster of transport devices illustrating several steps involved in moving the transport device of FIG. 2 horizontally across the cluster. [Figure 6b] 3A-3D show a series of schematic side views of a cluster of transport devices illustrating several steps involved in moving the transport device of FIG. 2 horizontally across the cluster. [Figure 6c] 3A-3D show a series of schematic side views of a cluster of transport devices illustrating several steps involved in moving the transport device of FIG. 2 horizontally across the cluster. [Figure 6d] 3A-3D show a series of schematic side views of a cluster of transport devices illustrating several steps involved in moving the transport device of FIG. 2 horizontally across the cluster. [Figure 6e] 3A-3D show a series of schematic side views of a cluster of transport devices illustrating several steps involved in moving the transport device of FIG. 2 horizontally across the cluster. [Figure 6f] 3A-3D show a series of schematic side views of a cluster of transport devices illustrating several steps involved in moving the transport device of FIG. 2 horizontally across the cluster. [Figure 7] FIG. 11 is a schematic perspective view of a storage system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In the figures, like features are designated with like reference numerals where appropriate.

[0039] The following detailed description refers to the accompanying drawings which show specific details and examples of how the invention can be practiced. These examples are described in sufficient detail to enable one skilled in the art to practice the invention. Other examples may be utilized and structural changes may be made without departing from the scope of the invention as defined in the appended claims. Additionally, directional references (including upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, side, above, below, front, middle, back, vertical, horizontal, height, depth, width, and any other term with an implied orientation) are provided as examples to aid the reader in understanding the specific examples described herein. They should not be construed as requirements or limitations on the specific position, orientation, or use of the invention unless specifically recited in the appended claims. Similarly, connection references (e.g., attached, coupled, connected, joined, fixed, etc.) should be interpreted broadly and may include intermediate members between connections of elements and relative movement between elements. Thus, a connection reference does not necessarily imply that two elements are directly connected and in fixed relation to each other, unless specifically recited in the appended claims.

[0040] FIG. 1 is a perspective view of a cluster 4 of transport devices 2 arranged in a three-dimensional physical topology according to an embodiment of the present invention. In this embodiment, the cluster 4 forms part of a storage and retrieval system 5, with the transport devices 2 tessellated to form a dense cluster 4, each comprising a receiving space 3 configured as a void for receiving an item. For example, the receiving space 3 may be arranged to hold products until they are packaged and shipped as part of a customer order. Alternatively, the receiving space 3 may be arranged to hold items for an inventory system. In this regard, it is envisaged that the cluster 4 comprises two or more transport devices 2 arranged to cooperate in a physical topology in which one transport device 2 may be rearranged by moving or being moved by interaction with another transport device 2 in the cluster 4. It is noted that in this embodiment, the cluster 4 does not comprise external means for facilitating the movement or relocation of the transport devices 2. Instead, advantageously, each transport device 2 comprises a mechanism that allows it to move within the cluster 4 and change the topology of the cluster 4 by cooperation with at least one other transport device 2. The cluster 4 may comprise an empty portion without a transport device 2, which is used to provide a place for the transport device 2 to move to during the repositioning of the cluster 4, and the empty portion is moved to the position vacated by the moved transport device 2. However, such an empty space may not be necessary if the cluster 4 does not occupy the entire space in which the cluster 4 is operating. For example, the cluster 4 comprises a stack of transport devices 2. Each stack is located adjacent to another stack. The transport devices 2 in each stack may cooperate with each other to cause the movement of a particular transport device 2 within and through the cluster 4. As shown in FIG. 1, the stack of transport devices 2 has a variable height, and even the number of stacks and the number of transport devices 2 in a stack may be variable and is not limited to a specific number. Furthermore, the cluster 4 may extend by any number of stacks and / or transport devices 2 in any of the x-, y-, and / or z-directions. In the cluster 4 shown in FIG. 1, an empty space is available for the movement of the transport devices 2.For example, if a cluster 4 is in a location that can hold the maximum height of four transport devices 2, it is clear that there will be free space since not all stacks will have four transport devices 2. In this example, four of the 16 stacks will have three transport devices 2, one less than the possible four transport devices 2. Furthermore, one stack will have two transport devices 2. Thus, free space is available to accommodate the movement of a transport device 2.

[0041] It is envisioned that the cluster 4 may be of any size or shape and / or may be used in any type of environment. Additionally, the conveyors 2 forming the cluster 4 may be of various sizes. For example, conveyors 2 of different widths, lengths, and / or heights are multiples of the width, length, and / or height (respectively) of the smallest conveyor 2 in the cluster 4. Such a configuration may, for example, allow for the storage and / or transport of items that are otherwise too large or heavy for smaller conveyors 2 or for reasons of energy or space efficiency.

[0042] As mentioned above, the cluster 4 has a reconfigurable topology, with each transport device 2 arranged to interact with at least one other transport device 2 to provide a mechanism for achieving reconfiguration of the cluster 4. Specifically, in this embodiment, each transport device 2 comprises a drive means (generally indicated at 6) for propelling the transport device 2 or a nearby transport device 2 within its horizontal vicinity. In this embodiment, the transport devices 2 are illustrated as rectangular parallelepipeds, each having four side surfaces 8, a top surface 10 and a bottom surface 12. Thus, in this particular arrangement, each transport device 2 can have up to four directly adjacent nearby transport devices 2 within its horizontal vicinity (hereinafter referred to as "horizontal nearby transport devices 2") and up to two nearby nearby transport devices 2 within its vertical vicinity (hereinafter referred to as "vertical nearby transport devices 2"). It will be appreciated that a transport device 2 located at a corner of the cluster 4 can have up to two horizontal nearby transport devices 2, and up to one vertical nearby transport device 2 if located in the top or bottom row of the cluster 4. However, it should be understood that the transport device 2 need not have a rectangular parallelepiped shape, and other embodiments are envisioned in which the transport device 2 is differently shaped, such as hexagonal, and / or differently sized.

[0043] In addition to the drive means 6, each transport device 2 further comprises a guide means 14 configured to interact with the drive means 6 of the horizontal proximity transport device 2 to direct the movement of the transport device 2 or the horizontal proximity transport device 2 within the cluster 4. The movement of the transport device 2 is thus performed without the use of an external or surrounding framework or an external loading robot. The guide means 14 is configured to move between an active state and a passive state. When in the active state, the guide means 14 is locked or fixedly engaged with the drive means 6 of the horizontal proximity transport device 2 to effect the movement of the transport device 2 or the horizontal proximity transport device 2 within the cluster 4, and when in the passive state, the guide means 14 is prevented from engaging with the drive means 6 of the horizontal proximity transport device 2, allowing the transport device 2 and the horizontal proximity transport device 2 to be separated, for example to move one transport device 2 away from the other in the cluster 4 for removal from the cluster 4, or to allow two transport devices 2 starting apart to move together and then to an engaged position.

[0044] Each transport device 2 further comprises one or more communication units (not shown) through which it is individually addressable. The addressability of each transport device 2 is different from physically addressing the transport device 2. Addressability is intended to refer to having an addressing scheme that can be used to send one or more commands, e.g., motion control commands, to an individual transport device 2 or a group of transport devices 2 to achieve a translation of one or more transport devices 2 to move one or more transport devices 2 from place to place. In other words, the addressability of each transport device 2 (intended for communication with each transport device 2) is independent of the location of the transport device 2 in the cluster 4. To this end, the one or more communication units are arranged to receive control signals for controlling its corresponding transport device 2. For example, one communication unit of the one or more communication units may receive a signal indicating that the transport device 2 should be started or stopped. Additionally or alternatively, the signal may indicate the direction in the cluster 4 in which the transport device 2 should move and / or the position in the cluster 4 in which the transport device 2 should be moved. Additionally or alternatively, the signal may indicate that the movement of the transport device 2 should be performed by a specific distance in a specific direction, for example, a fraction of the height / width / depth of the transport device or a multiple of the height / width / depth of the transport device 2. Thus, one or more communication units may command their corresponding transport devices 2 to move in the direction indicated by the signal to move the transport device 2 in the cluster 4 by interacting with its horizontally proximate transport device 2. Additionally or alternatively, one or more communication units may command the movement of the proximate transport device 2 such that the horizontally proximate transport device 2 may be displaced. In this way, the individual transport devices 2 may be displaced in the cluster 4 based on the signal received by the one or more communication units. Additionally or alternatively, one or more communication units may receive higher level commands, for example reset or self-test commands, which may be converted into one or more actuations, movements, communications, or any other actions. One or more communication units may further be arranged to send signals to a controller of the storage and retrieval system 5.The signal may indicate the state of operation of its corresponding transport device 2, i.e. whether the operation is completed or is about to start, its progress, additional information regarding the specific progress of the movement, or other information. Furthermore, the communication unit or units may indicate technical defects of its associated transport device 2 so that appropriate corrective measures can be taken.

[0045] With regard to control of individual transport apparatus 2 within a cluster 4, a transport apparatus 2 interacts or cooperates with at least one of its horizontally proximate transport apparatus 2 to effect relocation of the transport apparatus 2 or a horizontally proximate transport apparatus 2 to an alternative position within the cluster 4, or for example to facilitate separation of the transport apparatus 2 from the cluster 4. Such a control strategy is described in WO2019 / 068778A1 (in the name of Ocado Innovation Limited), the contents of which are incorporated herein by reference.

[0046] In particular, the controller is arranged to determine a path from a start location in the cluster 4 of at least one of the transport devices 2 to a destination location. The controller may further be arranged to determine a control signal based on the determined path and transmit it to one or more communication units to move their associated transport devices 2 according to the determined path. In this way, the controller may firstly determine a path of the transport devices 2 and secondly move the transport devices 2 along the determined path. Additionally or alternatively, the complete path from the start location of the transport devices 2 to the destination location may not be determined in advance, instead only one or more maneuvers may be determined at the start of the location transfer or the path may be recalculated after the start of the location transfer.

[0047] A route may be preferred for a number of reasons, including, but not limited to, shortest travel distance, low probability of encountering congestion, low total travel time, low probability of collision, low power usage, ease of switching to an alternative route, and ability to avoid obstacles, such as damaged transport devices 2, damaged routes, and / or route sections under repair. The controller may use various algorithms to identify, design, and / or control the movement of various connected transport devices 2. The controller may be configured to optimize the movement of the transport devices 2 by applying various algorithms to determine potentially advantageous routes from one location to another. Potential advantages may include shorter travel distances, less probability of encountering congestion, shorter travel time, lower power consumption, coordination with the movement of other transport devices 2, bypassing obstacles such as damaged transport devices 2 or damaged surface areas, or coordination with various workstation operations.

[0048] In addition to the above, the controller may also be configured to evaluate how to improve work assignments within cluster 4, product movements, and product placement, or to schedule when certain types of movements should occur and in what order they should occur, for example, depending on the application of various business rules and / or priorities. The controller may be configured to determine both inbound and outbound factors, for example, when making decisions regarding product placement. For example, the controller may estimate a delivery location for a product supply, estimate an outbound delivery of the product, and move the conveyor 2 accordingly.

[0049] The controller can determine which of one or more transport devices 2 should be involved in fulfilling an order or for any other purpose. The action of one or more transport devices 2 may typically require the transport device 2 to traverse the cluster 4 and / or to support adjacent transport devices 2 and / or to perform actions such as propelling a given transport device 2. Given a set of constraints and conditions, the controller can be configured to analyze various routes within the cluster 4 to determine one or more routes that are potentially preferred over other routes. These preferred routes can be provided to the transport devices 2 once, periodically, and / or dynamically to control the movement of the transport devices 2 throughout the cluster 4 and / or the role the transport devices 2 play within the cluster 4.

[0050] In some embodiments, the controller may be implemented using one or more servers, each including one or more processors configured to execute one or more sets of instructions stored on one or more non-transitory computer-readable media. Potential advantages of computer implementation include, but are not limited to, scalability, ability to handle large amounts of processing and computational complexity, increased reaction speed, ability to make quick decisions, ability to perform complex statistical analysis, and ability to perform machine learning, among others. The controller may be implemented in any number of ways, for example, the controller may be implemented as a distributed computing system. For example, some or all of the functions of the controller may be distributed on the transport device 2 itself. Given their respective destinations, one or more transport devices 2 may communicate with nearby transport devices 2 in the cluster 4 to coordinate their movements to each of them to achieve their objectives.

[0051] 2a-d are a series of perspective views of the transport device 2 in different rotational positions for use in the cluster 4 of FIG. 1. FIG. 2a shows a first vertical side edge 20 of the transport device 2 formed between adjacent first and second side surfaces 22, 24. Each of the sides 22, 24 carries a drive means 6, which in this embodiment comprises a set of four pinions 26 arranged in a square formation, each pinion 26 being located at an apex of the square formation. Each pinion 26 is operatively connected to an electric motor via a rotatable shaft and is arranged to rotatably engage a guide means 14 of the horizontal proximity transport device 2. The electric motor is controlled by one or more communication units such that each pinion 26 is rotatable about a respective rotation axis 28 extending at right angles to the side surface 22, 24 with which it is associated. An example of the guide means 14 is shown in FIG. 2b, showing the second vertical side edge 30. In this example, the second vertical edge 30 is formed between the second side 24 and a third side 32 that is positioned adjacent to the second side 24 and carries the guide means 14. In this example, the guide means 14, like the pinions 26, comprises a set of four racks 34 arranged in a square arrangement, with the center point of each rack 34 positioned at the apex of the square arrangement so as to be engageable with the respective pinions 26 of the horizontal proximity transport device 2. Each rack 34 is operatively connected to an electric motor via a rotatable shaft. The electric motor is controlled by the communication unit such that each rack 34 is rotatable about a respective rotation axis 36 extending perpendicular to the third side 32 between an engaged position in which the racks 34 are locked and engaged with the respective pinions 26 of the horizontal proximity transport device 2 to effect movement of the transport device 2 or the horizontal proximity transport device 2 within the cluster 4, and a disengaged position. In this way, the axis of rotation 36 about which the rack 34 can rotate is parallel to the axis of rotation 28 of the pinion 26 on the horizontal proximity transport device 2 .In this example, and in the example illustrated in FIG. 2c, which shows a third vertical side edge 37 formed between the third side 32 and a fourth side 38 also carrying a set of four racks 34, the racks 34 are held in a vertical engagement position and combine with the vertical fixed rack portion 16 to form a vertical rack for directing the vertical movement of the transport device 2 or the horizontal proximity transport device 2 within the cluster 4. The racks 34 can also be rotated and held in a horizontal engagement position, where the racks 34, together with the horizontal fixed rack portion 18, form a horizontal rack for engaging with the pinion 26 of the horizontal proximity transport device 2 for directing the horizontal movement of the transport device 2 or the proximity transport device 2 across the cluster 4. Finally, FIG. 2d shows a fourth vertical side edge 40 formed between the first side 22 and the fourth side 38. Thus, in this embodiment, the transport devices 2 comprise drive means 6 comprising two sets of four pinions 26, each set being provided on two adjacent sides 22, 24, and guide means 14 comprising two sets of four racks 34, each set being provided on the remaining two adjacent sides 32, 38. In this particular arrangement, each transport device 2 is positioned in the cluster 4 with the same orientation such that at least one side 22, 24 associated with the drive means 6 of any one transport device 2 always faces the side 32, 38 associated with the guide means 14 of the horizontal proximity transport device 2, such that any one transport device 2 can propel or be propelled by the horizontal proximity transport device 2 within the cluster 4.

[0052] As mentioned above, generally the guide means 14 of the transport apparatus 2 is configured to move between an engaged position in which it is locked engaged with the drive means 6 of the horizontal proximity transport apparatus 2 to effect movement of the transport apparatus 2 or horizontal proximity transport apparatus 2 within the cluster 4, and a disengaged position in which engagement with the drive means 6 is prevented and allows the transport apparatus 2 and the proximity transport apparatus 2 to be separated such that the transport apparatus 2 or horizontal proximity transport apparatus 2 may be removed from the cluster 4 or separated from each other within the cluster 4. In this embodiment of the transport apparatus 2 the engaged positions comprise a first engaged position which effects vertical movement of the transport apparatus 2 or proximity transport apparatus 2 and a second engaged position which effects horizontal movement of the transport apparatus 2 or proximity transport apparatus 2.

[0053] 3a-3c show the positional or spatial relationship between the guide means 14 of the transport device 2, i.e. the rack 34, and the drive means 6 of the horizontal proximity transport device 2, i.e. the pinion 26. In these figures, it can be seen that the axis of rotation 36 of the rack 34 and the axis of rotation of the pinion 26 are offset relative to each other, providing the necessary distance to allow the rack 34 to move between the engaged and disengaged positions. In this embodiment, the axis of rotation 36 of the rack 34 is located at the apex of a notional square 42 circumscribing the circumference of the pinion 26. Referring to each figure in turn, FIG. 3a shows the rack 34 on the third side 32 of the transport device 2 in a first engaged position and in locking engagement with the pinion 26 on the first side 22 of the horizontal proximity transport device 2. When the rack 34 is in this position, the rotation of the pinion 26 about its axis of rotation 28 causes either the transport device 2 with which the rack 34 is associated, or the horizontal proximity transport device 2 with which the pinion 26 is associated, to move vertically either upwards or downwards, depending on whether the pinion 26 is driven clockwise or counterclockwise. To effect a horizontal or lateral movement of the transport device 2 or the horizontal proximity transport device 2 within the cluster 4, the rack 34 is rotated about its axis of rotation 36 from a first engagement position to a second engagement position, as shown in FIG. 3b. From here, the pinion 26 is driven about its axis of rotation 28 to cause either the transport device 2 with which the rack 34 is associated, or the horizontal proximity transport device 2 with which the pinion 26 is associated, to move laterally either to the left or right, or forwards or backwards, depending on the viewpoint, depending on whether the pinion 26 is driven clockwise or counterclockwise. In addition to the two engaged positions, the rack 34 can also be driven about its axis of rotation 36 to a disengaged position, as shown in Figure 3c. In this embodiment, the disengaged position is approximately midway between the first and second engaged positions, where the distance between the respective pinions 26 and the rack 34 is at a maximum.

[0054] As mentioned above, when in the engaged position, the guide means 14 of one transport device 2 is locked into engagement with the drive means 6 of the horizontal proximity transport device 2. This means that the transport device 2 and the horizontal proximity transport device 2 cannot be separated by pulling one away from the other in the direction of the rotation axes 28, 36. To achieve this locked engagement, the guide means 14 comprises a retaining means 44 for maintaining the engagement between the guide means 14 and the drive means 6 while the guide means 14 is in the engaged position. With reference to Figures 4a and 4b, in this embodiment in which the guide means 14 comprises a rack 34, the retaining means 44 comprises two walls 46 extending along the longitudinal edges of the rack 34 so as to define a channel 47 in which the pinion 26 is received when the rack 34 is in one of the first or second engaged positions. When the rack 34 is in one of these positions, lateral movement of the pinion 26 is limited by the inner surface of the wall 46 acting against the plane of the pinion 26, preventing separation of the associated conveying device 2. When the rack 34 is moved to the disengaged or disengaged position, the channel 47 moves away from the pinion 26, as shown in Figure 4c, and the associated conveying device 2 can be laterally separated.

[0055] 5a-5h are a sequence of diagrams illustrating some steps involved in an example of repositioning a target transport device 52 within a cluster 4. With reference to FIG. 5a, the target transport device 52 is oriented within the cluster 4 in the same position as shown in FIG. 2b, with only the second side 24 carrying the drive means 6 and the third side 32 carrying the guide means 14 visible. All of the other transport devices 2 forming the cluster 4 are oriented in a similar manner. In this example, the starting location 54 of the target transport device 52 is at the bottom corner of the cluster 4, the destination location 56 is at the top of the central row of transport devices 2, and a single free space is provided immediately above the target transport device 52 within the cluster 4.

[0056] 5b, in a first step, the target transport apparatus 52 is moved upward to occupy free space within the cluster 4, resulting in new free space at the bottom corner of the cluster 4 at a start location 54. This movement of the target transport apparatus 52 is accomplished by moving the racks 34 on the third side 32 (not shown) of the first horizontal proximity transport apparatus 58 and the immediately above it transport apparatus 60 to a first engaged position to form a substantially continuous rack extending vertically along the combined height of the transport apparatuses 58, 60, and the set of pinions 26 on the first side 22 (not shown) of the target transport apparatus 52 is rotatably driven to move the target transport apparatus 52 upward. At the same time, the rack 34 on the fourth side 38 (not shown) of the target transport apparatus 52 is also held in the first engagement position, and the set of pinions 26 on the second side 24 of the second horizontal proximity transport apparatus 62 and the transport apparatus 64 immediately above it are rotatably driven to move the target transport apparatus 52 upwardly.

[0057] From here, the transport device 62, previously the horizontal neighbour of the target transport device 52, is moved laterally to occupy the free space, due to the interaction between the set of pinions 26 on its first side 22 (not shown) and the racks 34 on the third side 32 (not shown) of the horizontal neighbour transport device, and during the transition of the transport device 62 to the free space, the transport device 58 becomes one of the horizontal neighbour transport devices (see FIG. 5c). Prior to this movement, the set of racks 34 on the fourth side 38 of the transport device 62 is moved to a disengaged or disengaged position, preventing engagement with the set of pinions 26 on the second side 24 of the transport device 63, thereby allowing the separation of the transport devices 62, 63. The transport device 64 is then driven downwards, due to the interaction between the set of pinions 26 and the racks 34 on its adjacent side, to create a free space adjacent to the target transport device 52. First, a set of pinions 26 on the second side 24 (not shown) of the transport device 64 and a set of racks 34 held in a first engagement position on the fourth side 38 (not shown) of the target transport device 52 and the transport device 62 (see FIG. 5d) are used for this downward movement. At the same time, the set of racks 34 on the fourth side 38 of the transport device 64 is also held in a first engagement position and engages with the set of pinions 26 on the second side 24 of the transport devices 63, 65, which are then appropriately driven. Together with this, the set of pinions 26 on the first side 22 of the transport device 64 is appropriately driven along the set of racks 34 held in a first engagement position on the third side 32 of the centrally located transport device (not shown).

[0058] From here, the target transport device 52 is driven laterally to occupy the free space, as shown in FIG. 5e. This is done by interaction between the set of pinions 26 on the first side 22 (not shown) of the target transport device 52 and the racks 34 on the third side 32 (not shown) of the horizontal proximity transport device of which the transport device 60 is one. Specifically, the set of racks 34 is held in the second engaged position, forming together with the horizontal fixed rack portion 18 a substantially continuous horizontal rack 34 extending along the combined length of the horizontal proximity transport device, and the pinions 26 on the first side 22 (not shown) of the target transport device 52 are rotatably driven to move the target transport device 52 laterally into the free space. Additionally, prior to arriving at the new position adjacent the transport device 65, the racks on the fourth side 38 of the target transport device 52 are moved to a disengaged or unengaged position. Once in the correct position, the rack on the fourth side 38 of the target transport apparatus 52 is then moved to either the first or second engagement position.

[0059] In a next step, as shown in Fig. 5f, the transport apparatus 66 is moved downwards to occupy the free space made available by the lateral movement of the target transport apparatus 52. This movement is achieved by interaction between a set of pinions 26 on the first side 22 (not shown) of the transport apparatus 66 and a set of racks 34 held in a first engaged position on the third side 32 (not shown) of the transport apparatus 60, 68, and between a set of racks 34 on the fourth side 38 (not shown) of the transport apparatus 66 and a set of pinions 26 on the second side 24 of the target transport apparatus 52 and the transport apparatus 70 immediately above it.

[0060] The transport device 70 is then moved laterally to occupy the free space left by the downward movement of the transport device 66, due to the interaction between the set of pinions 26 on the first side 22 of the transport device 70 and the set of racks 34 on the third side 32 of the transport devices 68, 72, which are held in the second engagement position to form a substantially continuous rack 34 along most of the combined length of the transport devices 68, 72 (see FIG. 5g) with the horizontal fixed rack portion 18. Following this, in a final step, the target transport device 52 is moved upward to the destination location 56, as shown in FIG. 5h. In this example, the target transport device 52 has adjacent transport devices on its first, second and fourth sides 22, 24, 38, all of which interact with each other to complete its upward movement to the destination location 56. Specifically, the set of racks 34 on the fourth side 38 of the transport apparatus 66, 70 is held in a first engagement position, and the set of pinions 26 on the second side 24 of the target transport apparatus 52 is rotatably driven to move the target transport apparatus 52 upward. Meanwhile, the set of racks 34 on the other side, i.e., the fourth side 38, of the target transport apparatus 52 is also held in a first engagement position and interacts with the set of pinions 26 on the second side 24 of the transport apparatus 65, 74, which are rotatably driven to move the target transport apparatus 52 to the destination location. Finally, the set of racks 34 on the transport apparatus 72 and the third side 32 of the transport apparatus immediately below it are also held in a first engagement position for interacting with the set of pinions 26 on the first side 22 of the target transport apparatus 52 to drive the target transport apparatus 52 to the destination location 56. Although the above describes an exemplary movement of an individual transport device 2 across the cluster 4, it will be appreciated that one or more other transport devices 2 can move simultaneously throughout the cluster 4. It is also possible for two or more adjacent transport devices 2 to be linked by interaction between their drive means 6 and guide means 14 held in the first or second engagement position to form a chain of transport devices 2 that can be moved across the cluster 4 as a group.Through interaction between the appropriate sets of pinions and racks 26, 34, such a chain of transport devices 2 can move longitudinally or transversely across the cluster 4. Shaping a chain of transport devices 2 is particularly useful for accessing a transport device 2 in a cluster 4 that has broken down and can no longer contribute to propulsion across the cluster 4.

[0061] Although not described in relation to the aforementioned figures for the sake of brevity, vertical gaps are necessary between the rows of transport devices 2 to allow horizontal movement across the cluster 4 of transport devices 2. To this end, the transport device 2 generally comprises one or more recessed areas 86 formed in its top surface 10 and a corresponding number of retractable posts 88 extendable from its bottom surface 12. Specifically, the transport devices 2 of this embodiment having a rectangular parallelepiped shape each comprise four recessed areas 86 and four corresponding retractable posts 88 (see Figures 2a-d). The recessed areas 86 and the retractable posts 88 are spatially arranged to cooperate, in that the recessed areas 86 of a first transport device 2 are configured to receive the retractable posts 88 of a second transport device 2 positioned thereon to support the second transport device 2 above the first transport device 2 and define a gap therebetween. The recessed area 86 and the retractable post 88 therefore support the transport devices 2 arranged in a stack, as shown in FIG. 6a, and ensure their vertical alignment. In order to allow the target transport devices 52 to be moved horizontally to the destination location, the row of transport devices 2 extending above the horizontal path along which the target transport devices 52 move is held in a predetermined position above the horizontal path. This is done by holding their guide means 14 and / or the guide means 14 of their horizontal proximity transport devices 2 in a first or second engaged position. In fact, some of the guide means 14 of the transport devices and / or their horizontal proximity transport devices 2 may be held in a disengaged or disengaged position, provided that the row of transport devices 2 extending above the horizontal path is properly supported. In this way, the row of transport devices 2 is supported by their horizontal proximity transport devices 2. The retractable post 88 can then be retracted by suitable actuators controlled by the controller via one or more communication units, not necessarily simultaneously, so as not to interfere with the target transport devices 52 as they move along the horizontal path.Similarly, the target transport device 52 is supported by its horizontal proximity transport device 2 by moving its guide means 14 and the guide means 14 of its horizontal proximity transport device 2 to the second engagement position when crossing the horizontal path, and then its retractable post 88 is retracted so as not to impede the movement along the horizontal path, as shown in FIG. 6b. The target transport device 52 is then driven along the horizontal path to a destination location by the operation of its drive means 6 and the drive means 6 of its horizontal proximity transport device 2 when crossing the horizontal path, as shown in FIG. 6c-6e. Once at the destination location, the retractable post 88 of the transport device 2 forming the stack including the target transport device 52 can be extended to support the transport device 2, as shown in FIG. 6f. In some examples, the retractable post 88 can be used, for example, to transmit control signals and / or power between one or more communication units of different transport devices 2 and / or to power motors, actuators, etc.

[0062] FIG. 7 shows another system according to a second embodiment of the invention. Unlike the previous embodiment, in which the transport devices 2 cooperate to propel one or more transport devices 2 in the cluster 4, this embodiment comprises at least one transport device 2 located adjacent to a surface 80, which cooperate with each other to move one of the transport devices 2 or the surface 80 relative to the other of the transport devices 2 or the surface 80. In this particular example, it is the transport device 2 that moves relative to the surface 80, which is illustrated as a wall. In essence, the surface 80 reproduces the function of the horizontally adjacent transport device 2 in the previous embodiment. To this end, in this embodiment, the surface 80 comprises a guide means 14 and the transport device 2 comprises a drive means 6 associated with the face of the transport device 2 facing the surface 80, i.e. the first side 22. However, a person skilled in the art will understand that the surface 80 may alternatively comprise a drive means 6 or a combination of the drive means 6 and the guide means 14. The drive means 6 is configured to interact with the guide means 14 to effect movement of the transport device 2 relative to the surface 80. The drive means 6 and the guide means 14 of this embodiment are the same as in the previous embodiment in that they respectively comprise a set of pinions 26 and racks 34 which interact with each other to move one of the transport devices 2 or the surface 80 relative to each other. The set of racks 34 is movable between an active state in which it is positively engaged with the respective set of pinions 26 to effect the movement of the transport device 2 or the surface 80, and a passive state in which the drive means is not engaged and allows the transport device 2 and the surface 80 to be separated. The surface 80 may comprise individual cells 84a, 84b, 84c, where the transport device 2 always cooperates with at least one cell. In this way, the transport device 2 may move from cell to cell across the surface 80. For example, the transport device 2 may be moved from cell 84a to cell 84b in order to reconfigure the physical topology of a cluster 4 comprising a plurality of transport devices 2. In this way, a transport device 2 may be added to or removed from the cluster 4.Surface 80 is shown as adjacent to conveying apparatus 2, but may instead be arranged as a floor below the surface, provided that any surface of conveying apparatus 2 carries one of drive means 6 or guide means 14 to complement the other of drive means or guide means 14 on surface 80. Surface 80 may alternatively be positioned above conveying apparatus 2. Furthermore, more than one surface 80 may be used to move conveying apparatus 2 in more than one dimension. For example, one surface may be arranged below conveying apparatus 2 and another surface may be arranged as a wall on one side of conveying apparatus 2, allowing conveying apparatus 2 to move in any orthogonal direction to change the position of conveying apparatus 2.

[0063] This disclosure describes examples of how the invention can be practiced, and it will be understood by those skilled in the art that various approaches can be adopted without departing from the scope of the invention as defined by the appended claims.

[0064] For example, in some alternative embodiments, all faces of the transport device 2 may be solid such that the transport device 2 does not include a receiving space 3. A system using this type of transport device 2 may be reconfigurable to lift or support objects. Furthermore, the exemplary drive means 6 and guide means 14 given in this disclosure comprise a set of four pinions 26 and racks 34, respectively. Examples are envisaged in which the drive means 6 and guide means 14 include sets with different numbers of pinions 26 and racks 34. In some of these examples, each set of pinions 26 may include more pinions 26 compared to the number of racks 34 in the set of racks 34. In this case, the racks 34 will be sized and positioned to form a gap, allowing one or more of the pinions 26 to pass between the racks 34 during relative movement between the transport devices 2. The pinions 26 may not be associated with their own motors, the motors may be interconnected, or one skilled in the art may understand that not all pinion wheels of a face need to be driven, but may instead be passive wheels. Furthermore, each rack in the set of racks 34 may have its own independent motor and control system, which may be required to facilitate changing the direction of movement of the transport device. For example, when moving a transport device 2 supported on only one of its sides and changing from vertical to horizontal, the transport device 2 may move the upper rack of the set of racks 34 first. Alternatively, only one rack may be moved at a time to adequately constrain the position and orientation of the transport device 2 relative to the adjacent transport device 2 in the horizontal direction. Peripheral devices may also be used with the cluster 4 to facilitate adding or removing the transport device 2 to or from the cluster 4. A transport mechanism may be used on which the transport device 2 may be located to add or remove it from the cluster 4. Furthermore, the cluster 4 may be located in different locations for specific functions. For example, a first cluster may be located in a refrigerated environment and a second cluster may be located in an ambient environment. The first and second clusters may form first and second levels of a larger cluster.In this manner, a first cluster 4 may comprise conveyors 2 storing food items that do not require refrigeration (such as dry goods) and a second cluster 4 may comprise conveyors 2 storing food items that do require refrigeration (such as fresh produce). A customer order may be fulfilled by picking conveyors 2 comprising the food items that require refrigeration and the food items that do not require refrigeration ordered by the customer from the first and second clusters 4. It will be understood that this description is provided by way of example only and that food items that may be refrigerated or that may be stored at ambient temperature may equally be stored in either the first or second cluster 4. The invention as originally claimed in the present application is set forth below. [1] A system comprising one or more conveying devices, one of a guide means or a drive means connected to the surface; a first conveying device adjacent to the surface and comprising the other of the guide means or the drive means; wherein the drive means is configured to interact with the guide means to effect movement of one of the first transport device or the surface relative to the other of the first transport device or the surface; The system, wherein the guide means is configured to change between an active state in which it is securely engaged with the drive means to effect movement of the first transport device or the surface, and a passive state in which the drive means is not engaged and allows the first transport device and the surface to be separated. [2] The system of [1], wherein the first conveying device comprises the drive means and the surface comprises the guide means, and the surface forms part of a second conveying device. [3] The system described in [2], wherein the first transport device further comprises a guide means configured to interact with a drive means of the adjacent transport device to direct movement of the first transport device or an adjacent transport device within the cluster. [4] The system described in [2] or [3], wherein the second transport device further comprises a drive means for moving the second transport device or an adjacent transport device within the cluster. [5] The system described in [4] when dependent on [3], wherein each of the plurality of conveying devices has a rectangular parallelepiped shape, driving means are provided on two adjacent sides, and guide means are provided on the remaining two adjacent sides. [6] The system described in [5], wherein each transport device of the plurality of transport devices is positioned within the cluster in the same orientation such that at least one side associated with the drive means of any one transport device having at least one adjacent transport device faces a side associated with the guide means of the adjacent transport device. [7] The system described in any one of [1] to [6], wherein the guide means is provided with a retaining means for maintaining engagement between the guide means and the drive means while the guide means is in the active state. [8] A system described in any one of [1] to [7], wherein the guide means is configured to be held in at least one of a first position or a second position when in the active state, the first position and the second position being arranged to direct movement of the first conveying device or the surface across the cluster in a first direction and a second direction, respectively. [9] The system described in [8], wherein the first direction is substantially perpendicular to the second direction.

[10] A system described in any one of [2] to [9], wherein the drive means of the first conveying device is arranged to rotatably engage with the guide means of the second conveying device.

[11] The system of

[10] , wherein the guide means comprises a rack and the drive means comprises a pinion configured to engage the rack.

[12] The system described in

[11] , wherein the rack is movable to move the guide means between the active state and the passive state.

[13] The system described in

[12] , wherein the rack is rotatable about an axis of rotation parallel to an axis about which the pinion rotates.

[14] The system described in

[13] , wherein the rotation axes of the rack and pinion are offset relative to each other.

[15] The system described in

[14] , wherein the rotation axis of the rack is located at a vertex of a notional square circumscribing the circumference of the pinion.

[16] The system described in any one of

[12] to

[15] when dependent on [8] or any claim dependent thereon, wherein the rack further comprises a fixed portion extending in the first direction and the second direction.

[17] A system described in any one of

[11] to

[16] when dependent on [7] or any claim dependent thereon, wherein the retaining means comprises two walls positioned on either side of the rack defining a channel in which the pinion is received when the guide means is in the active state.

[18] The system described in any one of [1] to

[17] , wherein each conveying device of the plurality of conveying devices is provided with vertical alignment means for aligning with adjacent conveying devices within its vertical vicinity.

[19] The system described in

[18] when dependent on [5] or any claim dependent thereon, wherein the vertical alignment means comprises a recessed area formed in the top surface and a retractable post extending from the bottom surface, the recessed area of ​​any one transport device configured to receive the retractable post of an upper adjacent transport device to ensure vertical alignment of the transport devices.

[20] The system described in any one of [1] to

[19] , wherein at least one of the plurality of conveying devices has a larger or smaller volume compared to the other conveying devices.

[21] The system described in any one of [1] to

[20] , wherein each of the plurality of transport devices is individually addressable.

[22] A system described in any one of [1] to

[21] , wherein each of the plurality of conveying devices has a receiving space for holding inventory.

[23] The system of [1], wherein the surface is fixed.

[24] A conveying device for use in the system described in any one of [1] to

[23] .

Claims

1. 1. A system comprising one or more conveying devices, one of a guide means or a drive means connected to the surface; a first conveying device adjacent to said surface and comprising the other of said guide means or said drive means; wherein the drive means is configured to interact with the guide means to effect movement of one of the first transport device or the surface relative to the other of the first transport device or the surface; the guide means is configured to change between an active state in which it is positively engaged with the drive means to effect movement of the first transport device or the surface, and a passive state in which the drive means is not engaged and allows the first transport device and the surface to be separated; The system wherein the first transport apparatus comprises the drive means and the surface comprises the guide means, the surface forming part of a second transport apparatus.

2. The system of claim 1 , wherein the first transport apparatus further comprises a guide means configured to interact with a drive means of the adjacent transport apparatus to direct movement of the first transport apparatus or an adjacent transport apparatus within the cluster.

3. 3. The system of claim 2, wherein the second transport apparatus further comprises a drive means for moving the second transport apparatus or an adjacent transport apparatus within a cluster.

4. 4. The system of claim 3, wherein each conveying device of the plurality of conveying devices has a rectangular parallelepiped shape, the drive means being provided on two adjacent sides and the guide means being provided on the remaining two adjacent sides.

5. The system of claim 4, wherein each transport device of the plurality of transport devices is positioned in the cluster in the same orientation such that at least one side associated with a drive means of any one transport device having at least one proximal transport device faces a side associated with a guide means of the proximal transport device.

6. 6. The system of claim 5, wherein said guide means comprises a retaining means for maintaining engagement between said guide means and said drive means while said guide means is in said active state.

7. 7. The system of claim 6, wherein the guide means is configured to be held in at least one of a first position or a second position when in the active state, the first position and the second position being arranged to direct movement of the first transport device or the surface across the cluster in a first direction and a second direction, respectively.

8. The system of claim 7 , wherein the first direction is substantially orthogonal to the second direction.

9. 9. The system of claim 8, wherein said drive means of said first transport apparatus is arranged to rotatably engage said guide means of said second transport apparatus.

10. 10. The system of claim 9, wherein the guide means comprises a rack and the drive means comprises a pinion configured to engage the rack.

11. The system of claim 10 , wherein the rack is movable to move the guide means between the active state and the passive state.

12. The system of claim 11 , wherein the rack is rotatable about an axis of rotation parallel to an axis about which the pinion rotates.

13. The system of claim 12 , wherein the axes of rotation of the rack and pinion are offset relative to one another.

14. The system of claim 13 , wherein the axis of rotation of the rack is at a vertex of a notional square circumscribing a circumference of the pinion.

15. The system of claim 11 , wherein the rack further comprises a fixed portion extending in the first direction and in the second direction.

16. The system of claim 10 , wherein the retaining means comprises two walls positioned on either side of the rack that define a channel in which the pinion is received when the guide means is in the active state.

17. 5. The system of claim 4, wherein each transport of said plurality of transports comprises vertical alignment means for aligning with adjacent transports within its vertical vicinity.

18. 18. The system of claim 17, wherein the vertical alignment means comprises a recessed area formed in a top surface and a retractable post extending from a bottom surface, the recessed area of ​​any one of the transport devices being configured to receive the retractable post of an upper adjacent transport device to ensure vertical alignment of the transport devices.

19. The system of claim 1 , wherein at least one of the plurality of transport devices comprises a larger or smaller volume compared to other transport devices.

20. The system of claim 1 , wherein each transport device of the plurality of transport devices is individually addressable.

21. The system of claim 1 , wherein each of the plurality of transport devices comprises a receiving space for holding inventory.

22. The system of claim 1 , wherein the surface is stationary.

23. A transport device for use in a system according to any preceding claim.

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