Device for retrieving unit from storage system

Abstract

To provide a handling device for a storage system that can achieve miniaturization of the machine.SOLUTION: The storage system includes multiple rails or tracks arranged in a grid pattern above stacks of containers. The grid pattern is provided with multiple grid spaces, and each stack is positioned within the installation area of a single grid space. A stack handling device 100 is configured to move laterally over the rails or tracks above the stacks, and during use, a container receiving space 114 positioned above the rails or tracks is located beneath a vehicle module 112 that houses components such as electric power components, control components, drive components, and lifting components. During use, the stack handling device occupies an installation area corresponding to only a single grid space in the storage system.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an apparatus for retrieving units from a storage system, particularly, but not exclusively, to a robotic device for handling storage containers or bins in a storehouse comprising a grid of stacked units. [Background technology]

[0002] Some commercial and industrial activities require systems that allow for the storage and retrieval of numerous different products. One known system for the storage and retrieval of items from multiple product lines involves arranging storage bins or containers on rows of shelves arranged in aisles. Each bin or container holds multiple products of one product type. The aisles provide access between the rows of shelves so that the required products can be retrieved by a worker or robot patrolling the aisles. However, it is understood that the need for aisle space to access the products means that the storage density of such systems is relatively low. In other words, the amount of space actually used for product storage is relatively small compared to the amount of space required for the storage system as a whole.

[0003] Another approach that provides significant improvements in storage density is to stack containers on top of each other and arrange the stacks in rows, where the containers are accessed from above, eliminating the need for aisles between rows and allowing more containers to be stored in a given space.

[0004] Methods for handling containers stacked in rows have been well known for decades. In some such systems, free-standing stacks of containers are arranged in rows to reduce the storage volume associated with storing such containers while providing access to specific containers when needed, as described, for example, in U.S. Pat. No. 2,701,065. Access to a given container is made possible by providing a relatively complex lifting mechanism that can be used to stack the containers and to remove a given container from the stack. However, the cost of such systems makes them impractical in many situations and they are primarily commercialized for storing and handling large shipping containers.

[0005] The concept of using free-standing stacks of containers and providing a mechanism for retrieving and storing specific containers has been further developed, as described, for example, in EP 0 767 113 B (Cimcorp). Cimcorp discloses a mechanism for retrieving stacked containers using a robotic load handler in the form of a rectangular tube that is lowered around the stack and configured to grasp containers at any height in the stack. In this manner, several containers can be lifted from the stack at once. The movable tube can be used to move several containers from the top of one stack to the top of another, or to move containers from a stack to an external location or from an external location to a stack. Such a system can be particularly useful when all containers in a single stack contain the same product (understood as a single-product stack). The load handler can be used to move containers between single-product stacks, for example, to add multiple containers containing a single type of product to a storehouse, and to retrieve one or more containers from two or more single-product stacks to create a multi-product shipping stack. An example of this is acquiring crates of vegetables at a central warehouse to create multi-product orders for distribution to retail stores.

[0006] In the system described by Cimcorp, the height of the tube must be at least as high as the height of the highest stack of containers so that the highest stacked container can be extracted in only one run. Thus, when used in an enclosed space such as a warehouse, the maximum stack height is constrained by the need to accommodate the tubes of the load handling machine. Furthermore, the system is not well adapted for the selection of a single container from a multi-product stack.

[0007] Online retail businesses that sell multiple product lines, such as online grocers and supermarkets, need systems that can store tens or hundreds of thousands of different product lines. The use of single-product stacks in these cases is impractical because a significant amount of floor space would be required to accommodate all of the required stacks. Furthermore, it may be desirable to store only small amounts of some items, such as perishable or infrequently ordered items, making single-product stacks an inefficient solution.

[0008] Therefore, for some applications, the use of multi-product stacks, where the containers making up each stack may hold different products, is preferred to maximize the storage density of the system. The stored items must remain reasonably quickly and easily accessible so that multiple different items needed to fulfill a customer order can be retrieved from the storage system in an efficient manner, even if some of the required items are stored below some other containers at a lower height in the stack.

[0009] International Patent Application WO 98 / 049075 A (Autostore), the contents of which are incorporated herein by reference, describes a system in which a multi-product stack of containers is arranged inside a framework. A system of this type is shown diagrammatically in Figures 1 to 4 of the accompanying drawings.

[0010] As shown in Figures 1 and 2, stackable containers, also known as boxes 10, are stacked on top of each other to form stacks 12. Stacks 12 are arranged on a lattice frame structure 14 in a warehouse or manufacturing environment. Figure 1 is a schematic perspective view of frame structure 14, and Figure 2 is a top-down view of stack 12 of boxes 10 arranged within frame structure 14. Each box 10 typically holds multiple product items (not shown), which may be the same or may be of different product types depending on the application.

[0011] The frame structure 14 includes a plurality of upright members 16 supporting horizontal members 18, 20. A first set of parallel horizontal members 18 are vertically arranged with a second set of parallel horizontal members 20 to form a plurality of horizontal lattice structures supported by the upright members 16. The members 16, 18, 20 are typically fabricated from metal. The boxes 10 are stacked between the members 16, 18, 20 of the frame structure 14 such that the frame structure 14 protects the stack 12 of boxes 10 from horizontal movement and guides the vertical movement of the boxes 10.

[0012] The top elevation of the frame structure 14 includes rails 22 arranged in a grid pattern across the top of the stacks 12. With additional reference to Figures 3 and 4, the rails 22 support a plurality of robotic load handling devices 30. A first set 22a of parallel rails 22 guides movement of the load handling devices 30 in a first direction (X) across the top of the frame structure 14, and a second set 22b of parallel rails 22 arranged perpendicular to the first set 22a guides movement of the load handling devices 30 in a second direction (Y) perpendicular to the first direction. In this manner, the rails 22 enable movement of the load handling devices 30 laterally in two dimensions in the horizontal XY plane so that the load handling devices 30 can be moved to positions above any of the stacks 12.

[0013] Load handling device 30 is further described in Norwegian Patent No. 317366, the contents of which are incorporated herein by reference. Figures 3(a) and 3(b) are schematic perspective views of load handling device 30 from the rear and front, respectively, and Figure 3(c) is a schematic perspective front view of load handling device 30 lifting box 10.

[0014] Each load handling device 30 includes vehicles 32 positioned to travel in the X and Y directions on the rails 22 of the frame structure 14 above the stack 12. A first set of wheels 34, consisting of a pair of wheels 34 on the front side of the vehicles 32 and a pair of wheels 34 on the rear side of the vehicles 32, are positioned to engage two adjacent rails of the first set 22a of rails 22. Similarly, a second set of wheels 36, consisting of a pair of wheels 36 on each side of the vehicles 32, are positioned to engage two adjacent rails of the second set 22b of rails 22. Each set of wheels 34, 36 can be raised and lowered so that either the first set of wheels 34 or the second set of wheels 36 is engaged with the respective set of rails 22a, 22b at any given time.

[0015] When the first set of wheels 34 is engaged with the first set of rails 22a and the second set of wheels 36 is lifted off the rails 22, the wheels 34 can be driven using a drive mechanism (not shown) housed on the vehicle 32 to move the load handling device 30 in the X direction. To move the load handling device 30 in the Y direction, the first set of wheels 34 is lifted off the rails 22 and the second set of wheels 36 is lowered into engagement with the second set of rails 22b. A drive mechanism can then be used to drive the second set of wheels 36 to achieve movement in the Y direction.

[0016] The load handling device 30 is equipped with a crane device 40. The crane device 40 includes a cantilever arm 42 that extends laterally from the top of the vehicle 32. A gripping plate 44 is suspended from the cantilever arm 42 by four cables 46. The cables 46 are connected to a reeling mechanism (not shown) housed within the vehicle 32. The cables 46 may be reeled in or out from the cantilever arm 42 so that the position of the gripping plate 44 relative to the vehicle 32 can be adjusted in the Z direction.

[0017] Gripping plate 44 is adapted to engage the top of box 10. For example, gripping plate 44 may include pins (not shown) that mate with corresponding holes (not shown) in the edges forming the top surface of box 10, and sliding clips (not shown) that can engage the edges to grip box 10. The clips are driven into engagement with box 10 by a suitable drive mechanism housed within gripping plate 44, which is powered and controlled by signals sent through cable 46 itself or through a separate control cable (not shown).

[0018] To remove a box 10 from the top of the stack 12, the load handling device 30 is moved in the X and Y directions as needed so that the gripping plate 44 is positioned above the stack 12. The gripping plate 44 is then lowered vertically in the Z direction to engage the box 10 at the top of the stack 12, as shown in FIG. 3(c). The gripping plate 44 grasps the box 10 and is then pulled upward by the cable 46 with the box 10 attached. At the top of its vertical travel, the box 10 is housed under the cantilever arm 42 and held above the level of the rail 22. In this manner, the load handling device 30 can be moved to different positions in the XY plane, carrying the box 10 along with it for transporting the box 10 to another location. The cable 46 is long enough to allow the load handling device 30 to retrieve and place boxes from any height in the stack 12, including floor level. The vehicle 32 is heavy enough to counterbalance the weight of the box 10 and to remain stable during the lifting process. The weight of the vehicle 32 may be made up in part of the batteries used to power the drive mechanism for the wheels 34, 36.

[0019] As shown in FIG. 4, multiple identical load handling devices 30 are provided so that each load handling device 30 can operate simultaneously to increase the system's throughput. The system shown in FIG. 4 includes two specific locations, understood to be ports 24, where boxes 10 can be transported into and out of the system. An additional conveyor system (not shown) is associated with each port 24, so that boxes 10 transported to a port 24 by a load handling device 30 can be transported by the conveyor system to another location, such as a pick-up station (not shown). Similarly, boxes 10 may be moved by the conveyor system from an external location, such as a box filling station (not shown), to a port 24 and transported by a load handling device 30 to a stack 12 to replenish inventory in the system.

[0020] Each load handling device 30 can lift and move one box 10 at a time. If it is necessary to retrieve a box 10 that is not located at the top of the stack 12 (the "target box"), the box 10 that is resting on top (the "non-target box") must be moved first to allow access to the target box 10.

[0021] Each of the load handling devices 30 is under the control of a central computer. Each individual box 10 in the system is tracked so that the appropriate box 10 can be retrieved, transported, and replaced as needed.

[0022] The system described with reference to Figures 1-4 has many advantages and is suitable for a wide range of storage and retrieval operations. In particular, the system allows for very dense storage of products and provides a very economical way to store a wide range of different items in bins 10, while still allowing reasonably economical access to all bins 10 when retrieval is required.

[0023] For high capacity systems where speed of operation is important, it is important to maximize the performance of each of the load handling devices in terms of speed of operation, battery life, reliability, lifting capacity, stability, etc. Therefore, it would be desirable to provide a load handling device that offers improved performance in one or more of these areas.

[0024] It may also be desirable to increase the number of load handling devices in use at any one time to allow for an increase in the rate at which items can be retrieved from the storage system. For example, applicant's co-pending International Patent Application No. PCT / GB2013 / 051215, the contents of which are incorporated herein by reference, describes a storage system provided with a plurality of each of two different types of load handling devices. One type of load handling device is adapted to lift multiple boxes from a stack in a single run and allow a target box in the stack to be accessed by a second type of single-box load handling device. In such cases, it may be desirable to reduce the size of the load handling devices to minimize instances where the optimal travel path for one device is obstructed by the presence of the other device.

[0025] It is against this background that the present invention was conceived. [Prior art documents] [Patent documents]

[0026] [Patent Document 1] U.S. Patent No. 2,701,065 [Patent Document 2] EP0767113B [Patent Document 3] International Patent Application WO98 / 049075A [Patent Document 4] Norwegian Patent No. 317366 [Patent Document 5] International Patent Application No. PCT / GB2013 / 051215 Summary of the Invention

[0027] In one aspect, the present invention relates to a load handling device for use in a storage system comprising a grid frame accommodating multiple stacks of containers. The load handling device is positioned above the stacks of containers and is capable of lifting the containers from the stacks and laterally moving the containers to another location. Advantageously, each load handling device occupies substantially only a single grid space in the storage system.

[0028] Accordingly, the present invention provides a load handling device for lifting and moving stacked containers in a storage system comprising a plurality of rails or tracks arranged in a grid pattern above a stack of containers, the grid pattern comprising a plurality of grid spaces, with each stack positioned within a footprint of substantially only a single grid space, the load handling device configured to move laterally on the rails or tracks above the stacks, the load handling device comprising: a container receiving space positioned above the rails or tracks in use; and a lifting device arranged to lift a container from the stack into the container receiving space, wherein the load handling device has a footprint that, in use, occupies substantially only a single grid space in the storage system.

[0029] A load handling device according to an embodiment of the present invention includes a container-receiving space in which a container can be lifted, the container-receiving space being located below a vehicle module in which components such as power, control, drive, and lifting components are housed.

[0030] In a preferred embodiment of the present invention, the load handling device has an outer housing that substantially encloses the container receiving space, the outer housing preferably having a cuboid shape.

[0031] Locating the bulky components of the load handling device above the container-receiving space reduces the footprint of the load handling device compared to the cantilevered design shown in Figures 3(a)-3(c) described in Norwegian Patent No. 317366, in which the bulky components are housed in a vehicle module located to one side of the container-receiving space. Advantageously, the load handling device of the present invention occupies the space above only one stack of containers in the frame, in contrast to the cantilevered design shown in Figures 3(a)-3(c), which occupies the space above two stacks. This means that thanks to the present invention, the reduced footprint can accommodate more load handling devices, reducing the chance of one load handling device interfering with the optimal path of another, which can improve the efficiency of storage system operation.

[0032] The load handling device preferably includes a set of wheels for supporting the load handling device above the stack. For example, lateral movement of the load handling device may be guided by rails arranged above the frame. The rails may be arranged in a grid pattern to allow two-dimensional movement of the load handling device in a horizontal plane. The wheels may engage with the rails. Two sets of wheels may be provided, one set arranged to engage with a first set of rails to guide movement of the load handling device in a first direction, and the other set arranged to engage with a second set of rails to guide movement of the load handling device in a second direction.

[0033] In an embodiment of the invention, wheels are arranged around the container-receiving space. The wheels may be driven by one or more motors housed in the vehicle module. Drive may be transmitted from the motors of the vehicle module to the wheels by drive transmission means arranged around the container-receiving space. For example, the drive transmission means may comprise a suitable arrangement of pulleys and drive belts.

[0034] Alternatively, the wheels may be equipped with built-in motors, for example motors built into the wheel hubs. In this way, each wheel is its own container drive unit and no drive belt is required. This configuration is advantageous as it reduces the size of the load handling device and makes after-sales service easier.

[0035] One or both sets of wheels may be configured to be raised and lowered relative to the other set of wheels. One or more wheel lifting motors or other wheel lifting devices may be housed in the vehicle module for this purpose.

[0036] The vehicle module can house a hoist or crane device for lifting the container into the container-receiving space. The crane device can include one or more motors for lifting the container, and the or each motor of the crane device can be housed in the vehicle module.

[0037] The crane device may include a gripping device configured to grip the container from above. The gripping device may be suspended from a cable that may extend and retract from the vehicle to move the gripping device vertically.

[0038] In another embodiment, the load handling device is provided with a lifting device arranged to lift a single container from the stack into the container-receiving space. The lifting device may comprise a pair of lifting arms arranged on either side of the container-receiving space, in which case the lifting device may comprise a gripping device mounted between the ends of the arms and arranged to grip the container from above.

[0039] The load handling device preferably has a center of mass that is located substantially directly above the gripping device when the gripping device is lowered below the container-receiving space.

[0040] In another embodiment, the lifting device comprises a rod or cable arranged to engage a vertical passage formed in the side wall of the container. The passage may be accessed by an opening in the top surface of each container. In such a configuration, no vertical space is required in the storage system.

[0041] The rod or cable may carry a securing mechanism arranged to releasably engage the container. For example, the securing mechanism may include one or more laterally extendable arms for engaging a surface of the container. The securing mechanism may be remotely operated, for example, by a wire extending through a tubular bore in the rod or cable.

[0042] A load handling device according to another embodiment of the present invention comprises an upper portion, a lower portion including a container-receiving space, and hoisting means for lifting containers into the container-receiving space. The hoisting means preferably comprises a hoist motor housed in the upper portion above the container-receiving space. The lower portion preferably comprises a wheel assembly for facilitating lateral movement of the load handling device relative to the frame, and the upper portion also comprises at least one motor for driving one or more wheels of the wheel assembly.

[0043] The lower portion may include a frame structure for supporting the wheels of the wheel assembly. The frame structure may be disposed around the container-receiving space. For example, the container-receiving space may be bounded on four sides by the frame structure. One or more elements of the frame structure may be movable to raise and lower the first set of wheels relative to the second set of wheels, thereby facilitating engagement of either the first set of wheels or the second set of wheels with the first or second set of rails or tracks, respectively. The movable elements of the frame structure may be driven by a motor housed in the upper portion of the load handling device.

[0044] The load handling device of the present invention is preferably a self-propelled robotic vehicle.

[0045] From another aspect, the invention resides in a storage system comprising a frame housing a plurality of stacks of containers and one or more of the aforementioned load handling devices, each of which occupies substantially a single grid space corresponding to the area occupied by only one stack of containers.

[0046] Accordingly, the present invention provides a storage system comprising: a first set of parallel rails or tracks; and a second set of parallel rails or tracks extending across the first set in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces; a plurality of stacks of containers positioned below the rails, each arranged to occupy substantially the footprint of a single grid space; a load handling device as described above arranged to move laterally on the rails above the stacks; the load handling device comprising a container receiving space positioned above the rails and a lifting device arranged to lift a single container from the stack into the container receiving space, wherein the load handling device has a footprint that occupies substantially only a single grid space in the storage system.

[0047] In another aspect, the invention provides a storage system including a frame for housing multiple stacks of containers, a first handling device capable of lifting the multiple containers from the stack in a single operation, and a second handling device capable of lifting a single container and moving the container laterally. The first and second handling devices are positioned above the frame and are independently movable to access different stacks. The second handling device is of the type described above and occupies a space substantially corresponding to only one stack of the multiple containers.

[0048] In this embodiment, the provision of a first handling device capable of lifting multiple containers from a stack in a single operation, along with a second handling device capable of lifting a single container and moving the container laterally, provides an optimal solution when attempting to retrieve a container located in the middle or bottom of a stack. In such cases, only two lifting operations need be performed to retrieve the target container, which greatly improves the speed and efficiency of the retrieval process compared to prior art configurations in which only one container could be lifted at a time.

[0049] The storage system may further include one or more port locations where containers may be removed from and / or added to the storage system. The cargo handling device of the present invention may be capable of transporting target containers from the stack to the port locations. The containers may comprise topless boxes. The containers may be arranged to interlock or engage with each other vertically when formed in a stack.

[0050] In a typical application, multiple handling devices may be used so that multiple containers can be lifted and moved simultaneously. The handling devices may be of different types and may be selected to balance system cost and energy consumption with speed and flexibility of operation. One benefit of the present invention is that because the load handling devices occupy the space above only one stack, the efficiency of multiple-device systems may be improved compared to prior art load handling device designs that occupy the space of two or more stacks. Gains in efficiency may result from being able to fit more load handling devices into a given system, from optimizing device routing using the space gained by the reduced device footprint, or from a combination of these factors.

[0051] Preferred and / or optional features of each aspect of the invention may be used alone or in appropriate combination in other aspects of the invention.

[0052] Embodiments of the present invention will now be described, by way of example only, with reference to the remaining accompanying drawings in which like reference numerals are used for like features and in which: [Brief explanation of the drawings]

[0053] [Figure 1] FIG. 1 is a schematic perspective view of a frame structure for accommodating multiple stacks of boxes in a known storage system. [Figure 2] 2 is a schematic plan view of a portion of the frame structure of FIG. 1; [Figure 3] Figure 3(a) is a schematic perspective view from the rear of a known load handling device for use with the frame structure of Figures 1 and 2. Figure 3(b) is a schematic perspective view from the front of a known load handling device for use with the frame structure of Figures 1 and 2. Figure 3(c) is a schematic perspective view of the known load handling device in use lifting a box. [Figure 4] FIG. 4 is a schematic perspective view of a known storage system comprising a plurality of load handling devices of the type shown in FIGS. 3(a), 3(b), and 3(c) mounted on the frame structure of FIGS. 1 and 2. [Figure 5] FIG. 5 is a schematic perspective view of a load handling device according to an embodiment of the present invention. [Figure 6] Figure 6(a) is a schematic perspective view of the load handling device of Figure 5 with a portion of the load handling device cut away to show the interior of the device, Figure 6(b) is a schematic perspective view of the load handling device of Figure 5 with a portion of the load handling device cut away to show the interior of the device, and Figure 6(c) is a diagram of one possible system configuration of the device. [Figure 7] 7 is a schematic perspective view of a storage system including a plurality of known load handling devices of the type shown in FIGS. 3(a), 3(b), and 3(c) and a plurality of load handling devices of the type shown in FIG. 5, mounted on the frame structure of FIGS. 1 and 2; [Figure 8] FIG. 8 is a schematic side view of a load handling device according to another embodiment of the present invention, with the outer housing omitted. [Figure 9] FIG. 9 is a schematic perspective view of a load handling device according to another embodiment of the present invention, with the outer housing omitted. [Figure 10] FIG. 10 is a schematic top view of a load handling device according to another embodiment of the present invention, with the outer housing omitted. [Figure 11] FIG. 11 is a schematic perspective view of the load handling device of FIGS. 8-10 with the outer housing omitted. [Figure 12] FIG. 12 is a side view of the load handling device of FIGS. 8-11. [Figure 13] FIG. 13 is a schematic perspective view of a wheel suitable for use in the load handling device of FIGS. 8-12. [Figure 14] FIG. 14 is a schematic perspective view of a portion of a load handling device according to another embodiment of the present invention. [Figure 15] 15 is a schematic perspective view of the internal components of the load handling device of FIG. 14. [Figure 16] 16 is a schematic side view of the internal components of the load handling device of FIG. 14. [Figure 17] FIG. 17 is a perspective view of a load handling device according to a further embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0054] Figure 5 shows a load handling device 100 according to an embodiment of the present invention. The load handling device 100 includes a vehicle 102 having a hoist or crane mechanism 104 mounted thereon for lifting a storage container or box 106, also known as a returnable box, from above. The crane mechanism 104 includes a hoist cable 108 and a gripping plate 110. The gripping plate 110 is configured to grip the top of the container 106 to lift the container 106 from a stack of containers 106 in a storage system of the type shown in Figures 1 and 2.

[0055] Referring also to FIGS. 6( a ) and 6 ( b ), the vehicle 102 includes an upper portion 112 and a lower portion 114 .

[0056] The lower section 114 is fitted with two sets of wheels 116, 118 that run on rails mounted on the top of the storage system's frame. At least one wheel of each set 116, 118 is driven to enable movement of the vehicle 102 in the X and Y directions, respectively, along the rails. As will be explained later, one or both sets of wheels 116, 118 can be moved vertically to lift the wheels of each set off their respective rails, thereby allowing the vehicle 102 to move in a desired direction.

[0057] The wheels 116, 118 are arranged in the lower portion 114 around the periphery of a cavity or recess 120 known as a container-receiving recess. The recess 120 is sized to accommodate the box 106 when it is lifted by the crane mechanism 104, as shown in FIG. 6(a). When in the recess 120, the box 106 is lifted off the underlying rails to allow the vehicle 102 to move laterally to a different location. Upon reaching a destination location, such as another stack, an access point in a storage system, or a conveyor belt, the box 106 can be lowered from the recess 120 (as shown in FIG. 6(b)) and released from the gripper plate 110.

[0058] The upper section 112 of the vehicle 102 houses all of the critical and bulky components of the load handling device, as shown in Figure 6(c). The upper section 112 houses the batteries and associated electronics, controls and communication devices, motors for driving the wheels 116, 118, motors for driving the crane mechanism 104, and other sensors and systems.

[0059] In this manner, the footprint of the vehicle 102 is larger than the dimensions of the box 106 by enough to accommodate the wheels 116, 118 on either side of the recess 120. Stated another way, the vehicle 102 occupies a single grid space in the storage system. Therefore, in this manner, the vehicle 102 takes up the smallest possible amount of space in the XY plane, having a footprint roughly half that of the prior art cantilevered design shown in FIG. 3. For comparison, FIG. 7 shows a load handling device 100 according to the present invention in use in a storage system of the type shown in FIGS. 1 and 2, along with a prior art cantilevered load handling device 30 of the type shown in FIG. 3. It can be seen that the prior art device 30, while shorter in height, occupies the space of two stacks compared to the taller but smaller footprint device 100 of the present invention.

[0060] Because the container load is suspended between a pair of wheels on each side of the vehicle, the load handling device 100 of the present invention can also provide increased stability, increased load handling capacity, and reduced weight compared to the cantilevered prior art load handling device 30. In contrast, the prior art device 30 must have a relatively heavy vehicle module to counterbalance the load in a cantilevered configuration.

[0061] 8-12 illustrate one embodiment of the present invention. The upper section 112 of the vehicle 102 houses three main motors: a Z-axis drive motor 150 used to raise and lower a hoisting cable 108 wound around a spool 109 mounted on a drive shaft mounted on the opposite side of the vehicle 102; an X-axis drive motor 152 that drives a first set of wheels 116; and a Y-axis drive motor 154 that drives a second set of wheels 118. The vehicle upper section 112 also houses a battery 156 for powering the motors, controls, sensors, and other components, as described above with reference to FIG. 6(c).

[0062] Drive is transmitted from the X-axis drive motor 152 and the Y-axis drive motor 154 to the respective sets of wheels 116, 118 using belt drives. The X-axis drive motor 152 drives a pulley 160 connected to a short drive shaft 162 that extends across the vehicle body. Drive is transmitted from the short drive shaft 162 to each wheel in the first set of wheels 116 by an X-axis drive belt 164. The Y-axis drive motor 154 drives a pulley 170 connected to a long drive shaft 172 that extends across the vehicle body in a direction perpendicular to the short drive shaft 162. Drive is transmitted from the long drive shaft 172 to each wheel in the second set of wheels 118 by a Y-axis drive belt 174.

[0063] Belt drive wheels 116, 118 are mounted to the bottom of the lower section 114 of the vehicle 102. The motors 152, 154 can be mounted to the upper section 112 of the vehicle using drive belts 164, 174 to transfer drive from the motors to the wheels.

[0064] In this embodiment, the first set of wheels 116 can be raised off the rails or lowered onto the rails using a wheel positioning mechanism, as shown most clearly in Figures 9, 11, and 12. Each wheel 116 is mounted to an arm 180 that is pivotally mounted at its outer end. The inner end of each arm 180 is connected to the lower end of a respective linkage 182. The upper ends of both linkages 182 are connected to the lower end of a common linkage 184. In addition, the upper end of the common linkage 184 is connected to a lever arm 186 that is moved by a motor 188. By operating the motor 188 to pull the common linkage 184 upward, the first set of wheels 116 can be raised so that only the second set of wheels 118 are engaged with the rails, allowing movement of the vehicle 102 in the Y direction. Operating the motor 188 to push the common linkage 184 downward causes the first set of wheels 116 to move downward to engage the rails and lift the vehicle such that the second set of wheels 118 is lifted off the rails as shown in Figures 9, 11, and 12. Thus, the vehicle 102 can move in the X direction.

[0065] The second set of wheels 118 are mounted on fixed tees 190 located at either end of the lower section 114 of the vehicle 102 .

[0066] Figures 8, 9 and 12 show the load handling device 100 with a box 106 lifted into the recess 120. Figure 11 shows the load handling device 100 with a box 106 underneath the device 100 and the gripper plate 110 about to engage the box 106. The wheels 116, 118 and associated support pieces, linkages and drive belts 164, 174 are positioned around the edge of the recess 120 so that the upper part 112 of the vehicle 102 is firmly supported.

[0067] 13 shows a wheel 200 suitable for use as one of the wheels 116, 118 of the load handling device 100. The wheel 200 has a toothed center path 202 that forms a pulley for cooperation with the drive belts 164, 174. The path 202 is bounded by two rubber tires 204 that bear against a rail during use. The wheel 200 may be mounted to the arm 180 using an axle (not shown) that extends through an axle hole 206 in the wheel 200. The wheel design is compact and balanced to minimize wear, and the tires 204 align the drive belts 164, 174 during use.

[0068] Figure 14 shows two wheels 200 mounted on a frame structure 210 of a load handling device according to another embodiment of the invention. As in the previous embodiment, in this embodiment the load handling device comprises a vehicle with an upper part 112 housing the main components of the device and a lower part having a recess 120 for housing a box, with wheels 200 located on four sides of the recess (wheels on only one side are shown in Figure 14).

[0069] In this case, the frame structure 210 comprises two parallel panels between which the wheels 200 are housed. A drive belt 212 is provided to transmit drive from a motor housed in the upper part 112 of the vehicle to the wheels 200.

[0070] 15 and 16, the wheels 200 in this embodiment can be raised and lowered by moving the frame structure 210 relative to the vehicle upper section 112. The frame structure 210 is mounted to a body 230 of the vehicle upper section 112 using rails 232. The rails 232 are fixed to the body 230 in a vertical orientation, and the frame structure 210 is slidably mounted on the rails 232.

[0071] The frame structure 210 is held together by a pair of linkages 240 that extend between the panels. The bottom ends of the linkages 240 are attached to respective shafts 242 that span the gaps between the panels. The top ends of the linkages 240 are rotatably attached to threaded bosses 246 that are mounted on threaded horizontal drive shafts 244. The bosses 246 are slidably attached to horizontal rails 248.

[0072] The drive shaft 244 is driven by a motor 250 using a drive belt (not shown). When the drive shaft 244 is rotated in a first direction, the upper ends of the linkages 240 move apart to push the frame structure 210 downward, thereby lowering the wheels 200 onto the rails. When the drive shaft 244 is rotated in a second, opposite direction, the upper ends of the linkages 240 move together to pull the frame structure 210 upward, lifting the wheels 200.

[0073] Although only one frame structure 210 with two wheels 200 is shown in Figures 14-16, it will be understood that an identical frame structure 210 is provided on the opposite side of the vehicle. Both frame structures 210 are raised and lowered by a common motor so that this first set of wheels 200 can be raised and lowered in unison to control engagement of the four wheels 200 with rails extending in a first direction across the frame. Although not shown in Figures 14-16, the vehicle includes another set of wheels positioned to engage rails extending in a second, perpendicular direction across the frame when the first set of wheels is raised.

[0074] It will be appreciated that many different variations and modifications are possible. For example, both sets of wheels may be powered by a single motor, with an appropriate transmission arrangement to direct power to the appropriate set of wheels. In other embodiments, one or more of the wheels may include an internal motor or a motor positioned adjacent to the wheel. An example of this is shown in FIG. 17.

[0075] Referring to Figure 17, this shows a load handling device 252 according to a further embodiment of the present invention. The device 252 has a cuboid shaped outer housing 254 with a plurality of wheels 256 mounted near a lower edge 258 of the housing 254. The wheels 256 are motorized hub wheels, with each wheel 256 having a motor housed within the hub 260 of the wheel 256. The motors are used to directly drive each wheel 256, so this embodiment does not require a drive belt connected between the wheel and the drive motor.

[0076] In this example, the motor is powered by a battery located within sidewall 262 of lower portion 264 of housing 254, adjacent container-receiving space 266 of device 252. Locating the battery low in this manner has the advantageous effect of lowering the center of gravity of device 252, thereby improving the stability of device 252 and allowing for greater acceleration and deceleration. Device 252 is otherwise similar to the previous embodiment, containing a similar mechanism for raising and lowering wheels 256 and a similar lifting device for lifting a container into container-receiving space 266. The battery located in sidewall 262 is also used to power these components.

[0077] In any of the previously described embodiments, the mechanism used to lift the container into the container-receiving space can take any suitable form. For maximum stability and load capacity, it is desirable to provide four lifting cables, one cable near each corner of the device, although a different configuration, for example with fewer cables, may be used if desired. Conveniently, all cables are wound and unwound using a single motor, although two or more motors may be used if desired.

[0078] Instead of motors, the mechanism used to lift the wheels may use linear actuators such as linear motors or hydraulic rams. Other means of powering load handling devices instead of using battery power will be apparent to those skilled in the art, such as using overhead power or by supplying power via the rails on which the device runs.

[0079] It is understood that features described in connection with one particular embodiment may be interchanged with features described in connection with other embodiments. For example, the motor-mounted hub wheels described in connection with FIG. 17 may be used in any of the other embodiments, and / or the battery may be positioned lower adjacent to the container-receiving space in any of the embodiments to improve stability and enhance acceleration / deceleration. Other modifications and improvements not expressly described above will be apparent to the skilled reader.

Claims

1. 1. A storage system comprising a plurality of rails or tracks arranged in a grid pattern above a stack of a plurality of containers, comprising a load handling device for lifting and moving the stacked plurality of containers, the grid pattern comprising a plurality of grid spaces, each stack being positioned within the footprint of only a single grid space, the load handling device configured to move laterally on the rails or tracks above the stacks, the load handling device comprising:

1. A load handling device comprising: a container-receiving space located above said rail or track in use; and a lifting device arranged to lift a container from a stack into said container-receiving space, A load handling device characterized in that the load handling device has a footprint that, in use, occupies substantially only a single grid space in the storage system.

2. 2. The load handling device of claim 1, comprising an upper portion housing components such as power components, control components, drive components, and / or lifting components, and a lower portion including the container receiving space, wherein the lower portion is positioned directly below the upper portion.

3. 3. The load handling device of claim 1 or 2, further comprising an outer housing substantially enclosing the container-receiving space.

4. The load handling device of claim 3 , wherein the outer housing is shaped substantially as a cube.

5. 5. The load handling device of claim 1, wherein the load handling device is configured to move in a first direction along a first set of rails or tracks and in a second direction along a second set of rails or tracks, wherein the second direction is transverse to the first direction.

6. 6. A load handling device as described in any one of claims 1 to 5, wherein the load handling device comprises a wheel assembly comprising a first set of wheels for engaging with the first set of rails or tracks to guide movement of the device in a first direction, and a second set of wheels for engaging with the second set of rails or tracks to guide movement of the device in a second direction.

7. The load handling device of claim 6 , wherein the wheels are disposed around a periphery of the container-receiving space.

8. 8. A load handling device according to claim 6 or 7, further comprising a frame structure for supporting the wheels of the wheel assemblies.

9. The load handling device of claim 8 , wherein the frame structure is part of an outer housing of the load handling device.

10. 10. A load handling device according to claim 8 or 9, wherein the frame structure is arranged around the container receiving space.

11. A load handling device according to any one of claims 8 to 10, wherein the container-receiving space is defined within the frame structure.

12. A load handling device according to any one of claims 8 to 11, wherein the container-receiving space is bounded on four sides by the frame structure.

13. 13. A load handling device according to any one of claims 6 to 12, wherein one or more of the wheels are driven by a motor integrated into or positioned substantially adjacent to the wheel.

14. A load handling device according to any one of claims 6 to 13, wherein one or more of the wheels are provided with a wheel hub motor.

15. 15. A load handling device according to any one of claims 6 to 14, wherein one or more of the wheels are driven by one or more motors positioned above the container-receiving space.

16. 16. A load handling device according to claim 15, further comprising drive transmission means disposed about the container receiving space for transmitting drive from the motor to the wheels.

17. 17. A load handling device according to claim 16, wherein the drive transmission means comprises a pulley and drive belt arrangement.

18. 18. A load handling device according to any one of claims 6 to 17, wherein one or more of the wheels are provided with a path for cooperating with a drive belt for driving the wheel.

19. 20. A load handling device according to claim 18, wherein the path comprises a series of teeth for engaging corresponding formations on the drive belt.

20. 20. A load handling device according to claim 18 or 19, wherein the path is bounded by a pair of tires.

21. 21. A load handling device according to any one of claims 6 to 20, further comprising means for selectively engaging and disengaging the first set of wheels from the first set of rails, and means for selectively engaging and disengaging the second set of wheels from the second set of rails.

22. 22. A load handling device according to any one of claims 6 to 21, wherein one or both sets of wheels are arranged to be raised and lowered relative to the other set of wheels.

23. 23. The load handling device of claim 22, further comprising one or more wheel lifting devices positioned above the container receiving space and arranged to lift the wheels.

24. 24. The load handling device of claim 23, wherein the or each wheel-lifting device is configured to lift the wheels via a linkage located on a lower portion of the load handling device adjacent the container-receiving space.

25. 25. A load handling device according to any one of claims 1 to 24, wherein the lifting device comprises a gripping device configured to grip a container from above.

26. 26. The load handling device of claim 25, further comprising a lifting mechanism configured to raise and lower the gripping device relative to the container-receiving space.

27. 27. The load handling device of claim 26, wherein the lifting mechanism is positioned above the container receiving space.

28. 28. A load handling device according to claim 27, wherein the lifting mechanism comprises a motor.

29. 29. A load handling device according to claim 28, wherein the lifting mechanism further comprises a hoist arranged to be driven by the motor.

30. 30. A load handling device according to any one of claims 25 to 29, wherein the gripping device is suspended from a cable that can be extended and retracted from the load handling device to move the gripping device vertically.

31. 29. A cargo handling device as described in any one of claims 25 to 28, wherein the lifting device comprises a pair of lifting arms positioned on either side of the container receiving space, the gripping device mounted on the ends of the arms, and the arms configured to extend and retract to move the gripping device vertically.

32. 32. A load handling device according to any one of claims 25 to 31, wherein the load handling device has a centre of mass that is positioned directly above the gripping device when the gripping device is lowered below the container receiving space.

33. 33. The load handling device of any one of claims 1 to 32, wherein the load handling device is a self-propelled robotic vehicle.

34. 34. A cargo handling device according to any one of claims 1 to 33, further comprising one or more batteries for powering components of the device, wherein the batteries are located in a lower portion of the device adjacent the container receiving space.

35. 35. The load handling device of claim 34, wherein the battery is located within a sidewall of the device.

36. a first set of parallel rails or tracks and a second set of parallel rails or tracks extending across said first set in a substantially horizontal plane to form a grid pattern having a plurality of grid spaces; a plurality of stacks of containers positioned below the rails, each stack arranged to occupy the footprint of a single grid space; 36. A load handling device according to any one of claims 1 to 35, arranged to move laterally above the stack on the rail, the load handling device comprising a container-receiving space positioned above the rail and a lifting device arranged to lift a single container from the stack into the container-receiving space; A storage system comprising: A storage system, wherein the load handling device has a footprint that occupies substantially only a single grid space in the storage system.

37. 37. A storage system according to claim 36, wherein the storage system comprises a plurality of cargo handling devices according to any one of claims 1 to 35.

38. 38. The storage system of claim 36 or 37, further comprising one or more load handling devices capable of lifting multiple containers from a stack in a single operation.

39. 39. A storage system according to any one of claims 36 to 38, further comprising one or more port locations at which multiple containers may be removed from and / or added to the storage system.

40. 40. The storage system of claim 39, wherein the cargo handling device is configured to transport target containers from a stack to a port location.

41. 41. The storage system of any one of claims 36 to 40, wherein the container comprises an open-topped box.

42. 42. A storage system according to any one of claims 36 to 41, wherein the containers, when formed in a stack, are arranged to interlock or engage with one another in a vertical direction.

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