Device for removing a storage container from a storage and retrieval system

Abstract

A load handling apparatus for lifting and moving one or more stackable containers in a storage and retrieval system, the apparatus comprising a plurality of modular sections (132a), (134a), (136a), (138a) arranged in a vertical stack, the plurality of modular sections comprising a container lifting mechanism, a wheel assembly, a wheel positioning mechanism, and electrical components, each of the plurality of modular sections (132a), (134a), (136a), (138a) further comprising at least four connection blocks (140), each of the at least four connection blocks (140) comprising: The connection blocks (140) are connected to two other connection blocks (140) in a single modular section by one or more substantially horizontal connection elements (184) to form a rectangular frame (186), and at least four connection blocks (140) of vertically adjacent modular sections can be connected in a vertical stack by one or more substantially vertical connection elements (188) to form an open frame structure comprising a plurality of rectangular frames, the open frame structure being configured to support a container lifting mechanism, a wheel assembly, a wheel positioning mechanism and electrical components.

Description

Technical Field

[0001] The present invention relates to an apparatus for removing a storage container from a storage and retrieval system. Without limitation, in particular, the present invention relates to a robotic payload handling apparatus for handling storage containers in a storage and retrieval system having a grid framework structure.

Background Art

[0002] A storage and retrieval system 1 having a three-dimensional storage grid framework structure in which storage containers / bins are stacked on top of each other is well known. PCT Publication No. WO2015 / 185628A (Ocado) describes a known storage and fulfillment or logistics system in which a stack of containers or bins is arranged within a grid framework structure. The containers or bins are accessed by a remotely operable payload handling apparatus located on a track at the top of the grid framework structure. This type of system is schematically illustrated in FIGS. 1 to 3 of the accompanying drawings.

[0003] As shown in FIGS. 1 and 2, stackable containers known as storage containers or containers 10 are stacked on top of each other to form a stack 12. The stack 12 is disposed in a three-dimensional grid framework structure 14 in a warehouse storage environment or a manufacturing environment. The grid framework structure is composed of a plurality of storage columns or grid columns. Each grid in the grid framework structure has at least one grid column for storing a stack of containers. FIG. 1 is a schematic perspective view of the grid framework structure 14, and FIG. 2 is a top view showing a stack 12 of containers 10 disposed within the framework structure 14. Each container 10 typically holds a plurality of product items (not shown), and the merchandise items within the container 10 can be of different product types or of the same type depending on the application. The container 10 can be referred to as a storage container or container, or as a storage container or tote.

[0004] Specifically, the three-dimensional grid framework structure 14 includes a plurality of vertical uprights or upright members or upright columns 16 that support the horizontal grid members 18, 20. A first set of parallel horizontal grid members 18 is arranged perpendicularly to a second set of parallel horizontal grid members 20 to form a grid structure or grid 15 that includes a plurality of grid cells 17. The grid cells have openings to enable a load handling device to lift a container or storage vessel through the grid cells. In the grid structure, the first set of parallel horizontal grid members 18 intersect the second set of parallel horizontal grid members at nodes. The grid structure is supported by the upright members 16 at each of the nodes, or at the points where the grid members intersect, such that these upright members are interconnected at their upper ends by the intersecting grid members. The grid members 16, 18, 20 are typically manufactured from metal and are typically either welded together, bolted together, or a combination of both. The storage vessels or containers 10 are stacked between the upright members 16 of the grid framework structure 14, whereby the upright members 16 prevent horizontal movement of the stack 12 of containers 10 and guide vertical movement of the storage vessels 10.

[0005] The top level of the grid framework structure 14 includes rails 22 arranged in a grid pattern across the top of the stack 12. Referring further to FIG. 3, the rails 22 support a plurality of load handling devices 30. A first set 22a of parallel rails 22 guides movement of the robotic load handling devices 30 in a first direction (e.g., the X direction) across the top of the grid framework structure 14, and a second set 22b of parallel rails 22 arranged perpendicularly to the first set 22a guides movement of the load handling devices 30 in a second direction (e.g., the Y direction) perpendicular to the first direction. In this way, the rails 22 enable lateral movement of the robotic load handling devices 30 in two dimensions in the horizontal X-Y plane, such that the load handling devices 30 can be moved to any position above the stack 12.

[0006] A known load handling device or robotic load handling device, also known as the bot 30 shown in FIGS. 4 and 5 and comprising a vehicle body 32, is described in PCT Patent Publication No. WO2015 / 019055 (Ocado), which is incorporated herein by reference, where each load handling device 30 covers only a single grid space or grid cell of the grid framework structure 14. Here, the load handling device 30 comprises a pair of wheels at the front of the vehicle body 32 for engaging with a first set of rails or tracks for guiding the movement of the device in a first direction, and a pair of wheels 34 at the rear of the vehicle 32, a first set of wheels 34 comprising a pair of wheels 36 on both sides of the vehicle 32 for engaging with a second set of rails or tracks for guiding the movement of the device in a second direction, and a wheel assembly comprising a second set of wheels 36. Each of the sets of wheels is driven to enable movement of the vehicle in the X and Y directions respectively along the rails. One or both sets of wheels can be vertically moved to lift each set of wheels away from their respective rails, thereby enabling the vehicle to move in a desired direction, for example, the X or Y direction, on the grid structure.

[0007] WO2017 / 153583 (Ocado Innovation Limited) teaches a load handling device comprising a wheel positioning mechanism or steering mechanism for enabling lateral movement of the device in one of two transverse directions by enabling either the first set of wheels or the second set of wheels to selectively engage with the first or second set of rails or tracks (22a or 22b). This wheel positioning mechanism comprises a complex configuration of linkages driven by a linear actuator or motor for selectively lowering or raising either the first set of wheels or the second set of wheels to engage or disengage with the first set of rails or tracks or the second set of rails or tracks.

[0008] The load handling device 30 is equipped with a lifting mechanism or a container lifting mechanism or a crane mechanism for lifting the storage container from above. The crane mechanism includes a winch tether or cable 38 wound around a spool or reel (not shown), and a grappling device 39 in the form of a lifting frame. The lifting device includes a set of lifting tethers 38 (one tether near each of the four corners of the grappling device) connected near or at the four corners of the lifting frame 39, which is also known as a grappling device for releasable connection to the storage container 10 and extending in the vertical direction. The grappling device 39 is configured to releasably grip the upper part of the storage container 10 in order to lift the storage container 10 from a stack of containers in a storage system of the type shown in FIGS. 1 and 2.

[0009] The wheels 34, 36 are arranged at the lower part around a cavity or recess known as a container receiving recess 41. The recess is sized to accommodate the container 10 when the container 10 is lifted by the crane mechanism as shown in FIGS. 5(a and b). When within the recess, the container is lifted away from the lower rails, and as a result, the vehicle can move laterally to different locations. When reaching the target location, such as another stack, an access point within the storage system, or a conveyor belt, the container or storage container can be lowered from the container receiving portion and released from the grappling device. The container receiving space can comprise a cavity or recess arranged within the vehicle body, for example, as described in WO2015 / 019055 (Ocado Innovation Limited). Alternatively, the vehicle body of the load handling device can comprise a cantilever as taught in WO2019 / 238702 (Autostore Technology AS), in which case the container receiving space is located below the cantilever of the load handling device. In this case, the grappling device is hoisted by the cantilever, whereby the grappling device can engage with the container and lift the container from the stack into the container receiving space below the cantilever.

[0010] Typically, the load handling device comprises one or more electrical components such as a rechargeable power source and a control unit for supplying power to a drive unit for operating the lifting mechanism and the wheel positioning mechanism. For example, one or more load handling devices that are remotely operable on a grid structure are configured to receive instructions from a main control device to retrieve a storage container from a specific storage location within the grid frame structure. Wireless communication and networks can be used to provide a communication infrastructure from the main control device to one or more load handling devices operable on the grid structure via one or more base stations. The control device in the load handling device is configured to control various drive mechanisms to control the movement of the load handling device in response to receiving an instruction. For example, the load handling device can be instructed to retrieve a container from a storage column at a specific location on the grid structure. The instruction can include various movements in the X-Y directions on the grid structure. Upon reaching the storage column, the lifting mechanism is then operated to grasp the storage container and lift it into the container receiving space in the body of the load handling device, where it is then transported to another location on the grid structure, generally known as a drop-off port. The container is lowered to a suitable picking station to enable the retrieval of items from the storage container. The movement of the load handling device on the grid structure also involves the load handling device being instructed to move to a charging station, which is typically located around the grid structure. The electrical components of the load handling device are typically housed within the body of the load handling device.

[0011] Considering the number of components, including the various motors, pulleys, and electrical components such as batteries and control boards that are required for the payload handling device to operate on the grid framework structure, assembling the individual components together is one of the largest costs in the manufacture of the payload handling device. Considering that there are hundreds of payload handling devices that can operate on the grid framework structure, the cumulative cost of multiple payload handling devices that can operate on the grid structure represents a significant proportion of the cost of a typical storage and retrieval system. Not only does the cost of manufacturing the payload handling device represent a significant proportion of the cost of the storage and retrieval system, but the weight of the payload handling device, which can exceed 150 kg, can also lead to additional costs. For example, due to the weight of the payload handling device, the grid framework structure needs to have sufficient structural integrity to support the weight of multiple payload handling devices that can operate on the grid framework structure. Various bracing elements are used to increase the strength of the grid framework structure, which ultimately increases the cost of the grid framework structure and thus the overall cost of the storage and retrieval system. As the weight of the payload handling device increases, more power is also required to drive the wheel motors to move the payload handling device on the track at a sufficient speed, which in turn, in other words, means a larger and more powerful electric motor and a larger battery to supply the power required to drive this electric motor.

[0012] Therefore, there is a need for a payload handling device that is easy to assemble, lightweight, and has a lower manufacturing cost. SUMMARY OF THE INVENTION

[0013] The present invention alleviates the above problems by providing a load handling device or a robotic load handling device comprising a plurality of modules that can be connected to each other in a vertical stack, where each of the modules provides respective functional characteristics of the load handling device, such as a wheel assembly, a wheel positioning mechanism, a container lifting mechanism, and electrical components. The individual modules are connectable, enabling modules providing different functions of the load handling device to be stacked vertically. To connect the individual modules together, the individual modules comprise a plurality of connection blocks that provide connection points for stacking the modules. More specifically, the present invention provides a load handling device for lifting and moving one or more stackable containers in a storage and retrieval system, the storage and retrieval system comprising a grid structure comprising a plurality of grid members including a first set of grid members and a second set of grid members, the second set of grid members being substantially perpendicular to the first set of grid members, whereby the plurality of grid members are arranged in a grid pattern for guiding the movement of the load handling device on the grid structure, the load handling device comprising a plurality of modular sections arranged in a vertical stack, the plurality of modular sections a) a container lifting mechanism comprising a container gripping portion assembly configured to releasably grip a container and a drive mechanism configured to raise and lower the container gripping portion assembly; b) a wheel assembly comprising a first set of wheels for engaging a first set of grid members for guiding movement of the load handling device in a first direction and a second set of wheels for engaging a second set of grid members for guiding movement of the load handling device in a second direction, where the second direction intersects the first direction; c) a wheel positioning mechanism configured to selectively lower or raise the first set of wheels or the second set of wheels so as to engage or disengage from the first set of grid members or the second set of grid members; and comprising Here, each of the plurality of modular sections further comprises at least four connection blocks, and each of the four connection blocks is connected to two other connection blocks in a single modular section by one or more horizontal connection elements to form a rectangular frame, and at least four connection blocks of vertically adjacent modular sections can be connected in a vertical stack by one or more vertical connection elements to form an open frame structure with a plurality of rectangular frames, and the open frame structure is configured to support a container lifting mechanism, a wheel assembly, and a wheel positioning mechanism.

[0014] For the purposes of the present invention, each of the first and second sets of grid members may optionally comprise an orbit support to which an orbit system is attached, the orbit system comprising a first set of orbits attached to the first set of grid members and a second set of orbits attached to the second set of grid members. The orbit system can be a separate component from the grid members or, alternatively, the orbit system can be integrated into the grid members as a single unit, i.e., form part of the grid members. The load handling device is operable to move along the grid's orbits.

[0015] Optionally, the load handling device comprises one or more electrical components, for example, the one or more electrical components comprise a processor and / or a power source for controlling the container lifting mechanism and the wheel positioning mechanism.

[0016] Preferably, the open frame structure is a three-dimensional open frame structure that defines a volume for accommodating at least a part of the lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism, and / or the electrical components. For the purposes of the present invention, the term "open frame structure" is defined as a structure through which the operating parts inside the load handling device, for example, any one of the spools for carrying the lifting tether of the container lifting mechanism, and / or the power supply, and / or the control unit, can be seen from outside the load handling device. Preferably, the open frame structure defines a plurality of modular sections, and the plurality of modular sections include a lifting mechanism, a wheel assembly, a wheel positioning mechanism, and electrical components. The term "open frame structure" is construed to cover the load handling device without external cladding, whereby the internal components providing the functional features of the load handling device are visible from the outside.

[0017] Preferably, the rectangular frames vertically adjacent to the open frame structure define the volume region of the load handling device. For example, the open frame structure is a three-dimensional open frame structure.

[0018] At least four connection blocks not only enable different modular sections to be easily connectable in a vertical stack, but each of the at least four connection blocks can also be connected to two other connection blocks in a single modular section by one or more horizontal connection elements to form a rectangular frame. The connection between the connection blocks to two other corner connection blocks in a single modular frame can be made directly to two adjacent connection blocks or indirectly via another connection block.

[0019] Accordingly, a plurality of rectangular frames can be interconnected in a vertical stack by one or more vertical connecting elements to form an open frame structure. Different functions of the load handling device, such as a container lifting mechanism, a wheel assembly, a wheel positioning mechanism, and / or electrical components, are supported by the open frame structure. The term "supported" is broadly interpreted to include being physically supported by the open frame structure and / or forming part of the open frame structure.

[0020] To facilitate the assembly of the open frame structure, optionally, one or more horizontal and / or vertical connecting elements comprise connecting rods or tubes. The connecting rods can be easily gripped and assembled to the blocks in different rotational orientations. Thus, the assembly of the load handling device is made easier using the connecting blocks and connecting rods. Optionally, to assist in reducing the weight of the load handling device, the connecting rods comprise carbon fibers in a polymer matrix. To increase the structural integrity of the open frame structure, optionally, the rectangular frames in one or more of the plurality of modular hierarchical sections are braced by one or more bracing elements extending between one or more of the opposing horizontal connecting elements. Preferably, the one or more bracing elements comprise crossed bracing elements. In addition to the horizontal and vertical connecting elements providing structural support to the open frame structure, one or more bracing elements extend across the horizontal and / or vertical connecting elements. The one or more bracing elements can also provide additional support for securing one or more components of the lifting mechanism and / or the wheel assembly and / or the wheel positioning mechanism and / or the electrical components.

[0021] Optionally, at least four connecting blocks comprise four corner brackets, each corner bracket of the four corner brackets being connected to two other corner brackets in a single modular frame to form a rectangular frame.

[0022] To increase the ease with which rectangular frames can be connected together in a vertical stack, optionally, one or more vertical connecting elements extend vertically through one or more of at least four connection blocks of vertically adjacent rectangular frames in the vertical stack. In other words, the vertical element is common to one or more connection blocks of vertically adjacent rectangular frames. This allows an open frame structure to be constructed by individually attaching the rectangular frames to one or more vertical connecting elements. The number of modular sections, and thus the functional requirements of the load handling device, can be tailored by increasing the number of rectangular frames attached to one or more vertical connecting elements.

[0023] Preferably, one or more of at least four connection blocks of one or more of the plurality of modular sections are connected by joints to one or more horizontal and / or vertical connection elements. The connection between the horizontal connection element and the bracket by the joint optionally comprises a continuous glue channel. To increase the functionality of one or more of the four corner blocks, the continuous glue channel is integrated into one or more of the at least four connection blocks. Preferably, one or more of the at least four connection blocks comprise one or more injection points in fluid communication with the continuous glue channel for injecting an adhesive into the continuous glue channel. Optionally, one or more of the connection blocks comprise sockets for receiving the ends of connection rods or tubes. Preferably, the sockets are integrally formed within the connection blocks. To fix the connection rod or tube to the connection block, preferably, the socket has a substantially cylindrical inner wall, and the cylindrical inner wall has a groove that extends continuously around at least a portion of the cylindrical inner wall of the socket for axially distributing an adhesive along the receiving side end of the rod. The groove is configured to form a glue channel when the receiving side end of the connection rod is inserted into the socket. Preferably, one or more of the at least four connection blocks comprise one or more injection points in fluid communication with the groove for injecting an adhesive into the glue channel. This helps simplify connecting one or more blocks of one or more of the plurality of modular sections to horizontal and / or vertical connection elements.

[0024] Preferably, the open frame structure defines a volume for accommodating a container receiving space such that the installation area of the load handling device substantially occupies only the installation area of a single grid space or cell. The container receiving space is a space for accommodating a container in the open frame structure of the load handling device so that the load handling device can move on an orbit or a grid structure. The three-dimensional open frame structure defines a volume having an upper part and a lower part. The upper part accommodates auxiliary components of the load handling device, namely, a power supply, a control unit, and a wheel positioning mechanism, and the lower part accommodates the container receiving space.

[0025] One of the advantages of the load handling device being constructed from a plurality of connection blocks that are connected together to form a plurality of rectangular frames and stacked vertically to form an open frame structure is that the connection blocks provide not only structural components but also functional components to the load handling device. In other words, each of at least four connection blocks of each of the plurality of modular sections is a separate connection block that provides both structural and functional components of the load handling device. Since one or more of the connection blocks can combine both the structural and functional aspects of the load handling device, this eliminates the need for separate structural components that provide the structural integrity of the load handling device and separate functional components for the operation of the load handling device on the grid structure. Making one or more of the connection blocks of the open frame structure include both structural and functional components of the load handling device also reduces the number of parts when constructing the load handling device of the present invention, thus reducing the weight of the load handling device.

[0026] In an aspect of the present invention, one or more of at least four connection blocks in one or more of the modular sections provide at least a part of the function of the load handling device, and this function is any one of a container lifting mechanism, a wheel assembly, a wheel positioning mechanism, and / or an electrical component. Optionally, one or more of at least four connection blocks in one or more of the plurality of modular sections include one or more mounting bases for pulleys. Optionally, one or more of at least four connection blocks in one or more of the plurality of modular sections include one or more mounting bases for motors.

[0027] Optionally, at least a part of the lifting mechanism and / or the wheel assembly and / or the wheel positioning mechanism and / or the electrical component is integrally formed from one or more of at least four connection blocks in one or more of the plurality of modular sections that include at least a part of the lifting mechanism and / or the wheel assembly and / or the wheel positioning mechanism and / or the electrical component.

[0028] One or more of the connection blocks in one or more of the plurality of modular sections, that is, at least a part of the open frame structure, is integrally formed with at least a part of the lifting mechanism and / or the wheel assembly and / or the wheel positioning mechanism and / or the electrical component. For example, the mounting base for attaching each of the wheels of the wheel assembly can be integrally formed with one or more of at least four connection blocks.

[0029] Preferably, each wheel of the wheel assembly is attached to a wheel mounting base. Optionally, the wheel mounting base is integrally formed from a connection block of a predetermined modular section. In an aspect of the present invention, the connection block of the predetermined modular section comprises a first wheel mounting base for a wheel of a first set of wheels and a second wheel mounting base for a wheel of a second set of wheels, the first wheel mounting base and the second wheel mounting base comprising a plurality of bosses along the edges of the first wheel mounting base and the second wheel mounting base, each of the plurality of bosses of the first wheel mounting base and the second wheel mounting base comprising an axially aligned opening along a wheel positioning axis (the wheel positioning axis being a substantially vertical axis), the plurality of bosses of the first wheel mounting base and the second wheel mounting base being spaced apart such that the plurality of bosses of the first wheel mounting base and the second wheel mounting base engage with each other and the openings in each of the engaged bosses of the first wheel mounting base and the second wheel mounting base are axially aligned along the wheel positioning axis to receive a vertical connection element through their respective bosses. The spacing between the bosses of the first wheel mounting base and the second wheel mounting base is sufficiently large to allow the first wheel mounting base to move independently of the second wheel mounting base along the wheel positioning axis. A wheel mounting base having a first wheel mounting base for a wheel of a first set of wheels and a second wheel mounting base for a wheel of a second set of wheels allows the wheels attached to their respective first and second wheel mounting bases to move independently of each other along a vertical axis so as to engage with and disengage from a grid structure. The wheel mounting base operates in conjunction with a wheel positioning mechanism to redirect a load handling device on the grid structure.

[0030] Optionally, the wheel positioning mechanism comprises a cam mechanism and at least one of the at least four connection blocks comprises at least a portion of the cam mechanism. Optionally, at least a portion of the cam mechanism is integral with at least one of the at least four connection blocks.

[0031] In a further aspect of the present invention, the open frame structure provides a physical support for at least a portion of any one of the container lifting mechanism, the wheel assembly, the wheel positioning mechanism, and / or the electrical components. For example, a horizontal connecting element extending between opposing connection blocks can be used to physically attach one or more functional components of the load handling device. Optionally, the container lifting mechanism is a) a first set of spools and a second set of spools, wherein each spool of the first set of spools and the second set of spools carries a lifting tether having a first end fixed to the container gripping assembly and a second end fixed to the spool, b) a rotatable shaft, wherein the first set of spools and / or the second set of spools are attached to the rotatable shaft such that the rotatable shaft is common to the first set of spools and / or the second set of spools, c) a drive mechanism comprising a drive pulley attached to the common rotatable shaft of the first set of spools and / or the second set of spools such that rotation of the rotatable shaft by the drive pulley drives the rotation of the first set of spools and / or the second set of spools, and comprises.

[0032] Preferably, the rotatable shaft is attached to one or more horizontal connecting elements connecting two adjacent connection blocks. Preferably, the rotatable shaft extends between opposing horizontal connecting elements connected to the connection blocks.

[0033] Optionally, any one of the lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism, and / or the electrical components can be shared between two or more of the plurality of modular sections. For example, the wheel positioning mechanism includes a cam having a cam profile with a raised portion and a valley portion, a cam follower, and a traveler for moving the cam follower along the cam profile so as to convert the movement of the cam along the cam profile into vertical movement. The cooperation between the cam, the cam follower, and the traveler can be shared between two or more of the plurality of modular sections. Optionally, a plurality of vertically adjacent rectangular frames define a volume for accommodating at least a portion of the container lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism, and / or the electrical components. Optionally, one or more of the plurality of rectangular frames of the open frame structure, one or more of at least four connection blocks are 3D printed. Optionally, at least four connection blocks of each of the plurality of rectangular frames are 3D printed (e.g., formed by additive manufacturing).

[0034] The number of modular sections in a vertical stack can be provided according to the function of the load handling device. By having modular sections, the functional characteristics of the load handling device can be changed by changing the number of modular sections in the stack. In an aspect of the present invention, a plurality of modular hierarchical sections in ascending order of the height of the load handling device include first, second, third, and fourth modular hierarchical sections, the first modular hierarchical section being at the bottom of the load handling device, and the fourth modular hierarchical section being at the top of the load handling device. Preferably, the first modular section includes a wheel assembly for the load handling device to move on a grid structure. Preferably, the fourth modular section includes one or more cradles for supporting electrical components in order for the open frame structure of the load handling device to provide a container receiving space. Optionally, one or more cradles are attached to one or more of the horizontal connecting elements connecting two adjacent connection blocks of the fourth modular section.

[0035] A further aspect of the present invention provides a method of constructing a load handling device, the method comprising i) forming a rectangular frame by connecting together at least four connection blocks by one or more horizontal connecting elements; ii) connecting together a plurality of rectangular frames in a vertical stack by connecting connection blocks of vertically adjacent rectangular frames by one or more vertical connecting elements to form an open frame structure; comprising, the open frame structure a) a container lifting mechanism comprising a grappling device configured to releasably grip a container and a drive mechanism configured to raise and lower the grappling device; b) a wheel assembly arranged to support the vehicle body, wherein the wheel assembly comprises a first set of wheels for engaging a first set of grid members for guiding the movement of the load handling device in a first direction, and a second set of wheels for engaging a second set of grid members for guiding the movement of the load handling device in a second direction, the second direction being transverse to the first direction, and each wheel of the first set of wheels and the second set of wheels is mounted on a wheel mounting base, c) a wheel positioning mechanism configured to selectively lower or raise the first set of wheels or the second set of wheels so as to engage or disengage with the first set of tracks or rails or the second set of tracks or rails, supports.

[0036] Optionally, the open frame structure further supports one or more electrical components, and the one or more electrical components comprise a processor and / or a power source for controlling the container lifting mechanism and the wheel positioning mechanism.

[0037] Optionally, the open frame structure is formed by inserting one or more of a plurality of horizontal connecting elements and / or vertical connecting elements into openings in one or more of at least four connecting blocks. Optionally, the method further comprises attaching to the open frame structure at least a part of a lifting mechanism, and / or a wheel assembly, and / or a wheel positioning mechanism, and / or an electrical component.

[0038] According to the present invention, in order to reduce the weight of the load handling device and thus facilitate the construction of the load handling device, the method further comprises the step of integrally forming at least a part of the container lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism from one or more of at least four connection blocks of the open frame structure. By integrally forming at least a part of the functional components of the load handling device from the open frame structure, more specifically, from one or more of the connection blocks of the open frame structure, the number of components required to construct a load handling device having the desired functional characteristics of the load handling device operable on the grid frame work structure is reduced. Optionally, one or more of the connection blocks of at least four connection blocks of one or more of the plurality of rectangular frames are formed by 3D printing or additive manufacturing in order to capture the different complex shapes of at least a part of the container lifting mechanism, the wheel assembly, and the wheel positioning mechanism.

[0039] Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments made with reference to the drawings.

Brief Description of the Drawings

[0040]

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[0041] The present invention has been devised with respect to known features of storage systems such as the grid framework structure and the load handling device described above with reference to FIGS. 1 to 5. FIG. 6 is a schematic view of an example of the load handling device 130 according to the present invention. A typical load handling device in the art comprises a separate rigid framework or chassis, and functional components of the load handling device, such as a lifting mechanism, a wheel positioning mechanism, a wheel assembly, a wheel drive assembly, and electrical components, e.g., a rechargeable power source and / or a control unit, etc., are literally fixed or attached to the framework. The fixing includes various fasteners such as bolts, screws and / or welding. The framework is usually in the form of a tower having a height representing the height of the load handling device. To ensure the structural integrity of the rigid framework that supports the weights of the various functional components of the load handling device, the rigid framework is generally constructed from a metal, e.g., aluminum or stainless steel. Cladding is fixed to the outside of the framework to form a vehicle body that houses the functional features of the load handling device. The accumulation of the weight of the rigid framework and the various functional components of the load handling device results in a load handling device having a weight exceeding 150 kg. Compared with load handling devices in the art, the present load handling device has no cladding and mostly has an open frame structure.

[0042] According to an embodiment of the present invention, the construction of the load handling device 130 according to the present invention shown in FIG. 6 is based on the principle of having a modular system comprising a plurality of modules or modular sections that can be connected in a vertical stack to provide different functional features of the load handling device. In a further aspect of the present invention, the modular system is integrated into an open frame structure or framework 131 such that the open frame structure comprises a plurality of modular frames that can be connected to each other in a vertical stack to provide different functional features of the load handling device. The terms "open frame structure" and "framework" are used interchangeably in this patent specification to mean the same feature. In yet a further aspect of the present invention, at least a portion of the functional components of the load handling device are integrally formed within the open frame structure of the load handling device. An example of a load handling device 130 incorporating the inventive concept of the present invention is shown in FIG. 6, and different modular sections providing different functional features of the load handling device are shown in FIGS. 8(a and b). The different modular sections 132(a and b), 134(a and b), 136(a and b), 138(a and b) are labeled as the first, second, third, and fourth modular sections, respectively, in FIGS. 8(a and b). As can be understood from the exploded view of the load handling device shown in FIGS. 8(a and b), the different modular sections of the load handling device comprise connection points 140 at the corners of the modules 132(a and b), 134(a and b), 136(a and b), 138(a and b) to enable the different modular sections to be stacked vertically.

[0043] In certain embodiments of the present invention shown in FIGS. 8(a) and 8(b), four modular sections 132(a and b), 134(a and b), 136(a and b), 138(a and b) are shown connectable in a vertical stack to form a hierarchical-based modular system. Starting from the bottommost modular section 132(a and b), the four modular sections, where the height of the load handling device increases, are labeled, for the purposes of the description of the present invention, as the first modular section 132(a and b), the second modular section 134(a and b), the third modular section 136(a and b), and the fourth modular section 138(a and b). The four modular sections provide different functional features of the load handling device. In certain embodiments of the present invention, the different functional features of the load handling device may be shared among one or more of the modular sections 132(a and b), 134(a and b), 136(a and b), 138(a and b) of the load handling device 130. For example, the wheel positioning mechanism and the wheel drive assembly may be shared among two or more modular sections of the load handling device. The number of modular sections is not limited to four modular sections, and the different functional features of the load handling device may be divided among any number of modular sections.

[0044] The different functional features of the load handling device include, but are not limited to, a wheel assembly for enabling movement of the load handling device on a grid structure or track, a wheel drive assembly for driving the wheel assembly to enable the load handling device to move on the grid structure, a wheel positioning mechanism also known as a steering mechanism, a container lifting mechanism for picking up and dropping off containers to and from the grid cells of the grid framework structure, and the electrical or electronic components of the load handling device. As described in the introductory part of this patent specification, the electrical components may optionally include a control unit for controlling the operation of the drive mechanisms of the wheel drive assembly, the wheel positioning mechanism, and the container lifting mechanism. Typically, the drive mechanisms of the wheel drive assembly, the wheel positioning mechanism, and the container lifting mechanism include one or more electric motors. Other components of the electrical components of the load handling device include, but are not limited to, a power source for supplying power to drive the drive mechanisms of the wheel drive assembly and the container lifting mechanism. Typically, the power source is a rechargeable power source or a battery. Examples of rechargeable batteries include lithium-ion batteries, nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion polymer batteries, thin-film batteries, and smart battery carbon foam-based lead acid batteries.

[0045] In particular, for the purpose of facilitating the explanation of the architecture of the open-frame structure, the different functional features of the load handling device 130 shown in FIG. 6 are first described. However, the present invention is not limited to the examples of the different functional features of the load handling device described below, and other examples that can provide the same functional features of the load handling device are also applicable in the present invention. The description of the functional features of the load handling device aims to provide examples of the functional features of the load handling device.

[0046] [Wheel Assembly] As shown in FIG. 6, the wheel assembly includes a pair of wheels at the front of the load handling device 130 and a pair of wheels at the rear. For simplicity of explanation, the wheel assembly includes a pair of wheels at the front of the load handling device and a pair of wheels at the rear of the load handling device, which are collectively referred to as the first set of wheels 134. The first set of wheels 134 is oriented such that the load handling device can move in a first direction, i.e., the X Cartesian direction. Similar to the first direction, for movement in a second direction, the second direction is substantially perpendicular to the first direction, i.e., the Y Cartesian direction, whereby the load handling device can move in both the X and Y directions on the grid structure. The wheel assembly includes a pair of wheels on both sides of the load handling device. For simplicity of explanation, these wheels are referred to as the second set of wheels 136. Therefore, for movement in the first direction on the grid structure, the first set of wheels 134 engages with the grid structure, and the second set of wheels 136 disengages from the grid structure. Similarly, for movement in the second direction, the first set of wheels 134 disengages from the grid structure, and the second set of wheels 136 engages with the grid structure. The wheels are rotatably attached to the open frame structure 131 via one or more wheel mounts 139, 141 (see FIG. 8) and are configured to engage with the grid structure to enable the load handling device to move in both the X and Y directions along the grid structure.

[0047] To enable the load handling device to move in the first and second directions on the grid structure, the load handling device further includes a wheel drive assembly configured to drive each of the wheels of the wheel assembly.

[0048] [Wheel Drive Assembly] In certain examples of the present invention, each of the first and second sets of wheels is driven by one or more motors (not shown) via a drive belt assembly 140 described in PCT application PCT / EP2021 / 055372 in the name of Ocado Innovation Limited, the details of which are incorporated herein by reference. In the particular embodiment shown in FIG. 6, the drive belt assembly 140 is provided for each set of wheels and comprises a drive belt pulley gear arrangement 142 for engaging the edges of a pair of wheels 134, 136 on one side of the load handling device. The rims of these pairs of wheels comprise a plurality of gear teeth 144 for cooperating with the drive belt 146. A toothed drive belt engages both of these wheels. The drive belt 146 is guided by a driven wheel 148 attached to the open frame structure 131 of the load handling device 130 and two tensioning wheel arrangements 150. The tensioning wheel arrangements 150 are movably attached to the open frame structure 131 by springs (not shown) and are intended to keep the drive belt 146 taut and maintain the engagement of the drive belt with the wheels. A drive wheel 151 is provided and attached to the open frame structure 131. The drive wheel 151 is driven by a pulley and gear arrangement 142 connected to the axle or drive shaft of a motor (not shown in FIG. 6). The rotation of the drive wheel 151 by the motor drives the pair of wheels by virtue of being connected to the drive belt 146. The wheel drive assembly is provided for each of the pair of wheels of the first set of wheels 134 and the second set of wheels 136. Thus, each of the pair of wheels of the first set of wheels 134 is synchronously driven by its respective drive assembly to move the load handling device in the X direction on the grid structure. Similarly, each of the pair of wheels of the second set of wheels 136 is synchronously driven by its respective drive assembly to move the load handling device in the Y direction on the grid structure.

[0049] The drive wheels 151 on the opposing side portions of the load handling device 131 may share a common motor axle such that each pair of drive wheels 151 is driven simultaneously and at the same speed. As a result, only a single motor is required to drive the load handling device 130 in the forward and reverse directions in the first x direction, and only a single motor is required to drive the load handling device 130 in the forward and reverse directions in the second y direction. This configuration can advantageously reduce costs in terms of the space and the number of parts required in the load handling device. The first set of wheels 134 and the second set of wheels 136 can be selectively driven under the control of the load handling device.

[0050] A particular example of the wheel drive assembly in FIG. 6 comprises a drive belt assembly 140 driven by a motor, although other configurations for driving the first and second sets of wheels are applicable in the present invention. For example, it will be understood that it may be possible to drive the load handling device using four motors for each of the first and second directions. For example, all of the wheels in the first and second sets of wheels can be driven by individual hub motors comprising an outer rotor configured to rotate about an inner hub. Specifically, the outer rotor comprises an outer surface arranged to engage with a grid structure (e.g., a track), and an inner surface comprising a ring-shaped permanent magnet arranged to rotate about an inner hub comprising a wheel hub or a stator of the hub motor. Typically, the stator comprises the coils of the hub motor. To drive each wheel of the first set of wheels 134 or the second set of wheels 136 and thus move the load handling device 130 in the first or second direction on the grid structure, the outer rotors of the hub motors are arranged to rotate about an axis of rotation corresponding to the central axis of each respective wheel. The outer surface of the rotor may optionally comprise a tire for engaging with a track or rail.

[0051] [Wheel positioning mechanism] To enable the load handling device 130 to move on different wheels 134, 136 in the first and second directions, the load handling device 130 includes a wheel positioning mechanism or a direction changing mechanism for selectively engaging either the first set of wheels 134 with the first set of tracks 22a or the second set of wheels 136 with the second set of tracks 22b. The wheel positioning mechanism is configured to raise and lower at least one of the first set of wheels 134 and / or the second set of wheels 136 relative to the open frame structure 131 of the load handling device 130, thereby enabling the load handling device 130 to selectively move in either the first direction or the second direction across the tracks of the grid frame structure 1.

[0052] The wheel positioning mechanism may include one or more linear actuators, rotating components, or other means for raising and lowering at least one of the sets of wheels 134, 136 relative to the open frame structure 131 of the load handling device 130 to place at least one of the sets of wheels 134, 136 in a non - contact and a contact state with the tracks. In some examples, only one set of wheels is configured to be raised and lowered, and the operation of lowering one set of wheels can effectively lift the other set of wheels away from the corresponding tracks, while the operation of raising one set of wheels can effectively lower the other set of wheels into contact with the corresponding tracks. In other examples, both sets of wheels can be raised and lowered, and advantageously, the body or the open frame structure 131 of the load handling device 130 remains at substantially the same height, meaning that the weight of the body or the open frame structure 131 and the components mounted thereon need not be lifted and lowered by the wheel positioning mechanism.

[0053] In certain embodiments of the present invention, the wheel positioning mechanism comprises cam mechanisms 152 on each side of the load handling device 130. In FIG. 6, a cam mechanism 152 is shown on the visible X-direction side, and a similar cam mechanism 152 is also disposed on the opposite X-direction side (not shown). Similarly, a cam mechanism 152 is shown on the visible y-direction side, and a similar cam mechanism 152 is also disposed on the opposite y-direction side (not shown). In other words, the cam mechanisms 152 on each side of the load handling device 130 are configured to raise and lower a pair of wheels with respect to the open frame structure 131 of the load handling device 130. Each cam mechanism 152 on the opposing sides of the load handling device is configured to synchronously raise and lower each pair of wheels of the first set of wheels 134 or the second set of wheels 136 with respect to the open frame structure 131 of the load handling device 130 in order to move the load handling device in the X direction or the Y direction on the grid structure. Specifically, the cam mechanism 152 comprises a cam 154 having a cam profile 156 and a cam follower 158 engageable with the cam profile 156. In the particular embodiment of the present invention shown in FIG. 6, the cam follower 158 is a roller that rotates freely around a rotating shaft or spigot. The cam follower 158 is configured to move along the longitudinal direction of the cam profile 156.

[0054] The cam 154 includes a slot having a contour 156 that extends longitudinally along the slot between a first limit or lower limit 160 (valley portion) and a second limit or upper limit 162 (crest portion). Between these limits, the slot has sufficient space to accommodate the cam follower 158, extends substantially horizontally from the lower limit 160, slopes upward, and continues substantially horizontally to the upper limit 162. The movement of the cam follower 158 from the lower limit 160 to the upper limit 162 moves one or more wheels of the first set of wheels 134 or the second set of wheels 136 upward to disengage from the track. Similarly, the movement of the cam follower 158 from the upper limit 162 to the lower limit 160 moves one or more wheels of the first set of wheels 134 or the second set of wheels 136 downward to engage with the track. One or more wheels of the first set of wheels 134 or the second set of wheels 136 can be coupled to either the cam 154 or the cam follower 156 via their respective wheel mounts such that the movement of the cam follower 156 relative to the cam 154 raises and lowers one or more wheels of the first set of wheels 134 or the second set of wheels 136.

[0055] A pair of wheels on the same side of the load handling device may share the same cam and cam follower such that movement of the cam follower along the cam simultaneously raises or lowers the pair of wheels. A pair of wheels on opposite sides of the load handling device represents a first set of wheels for moving the load handling device in the X direction, and a pair of wheels on the other opposite side of the load handling device represents a second set of wheels for moving the load handling device in the Y direction. In other words, the cam mechanism provides a single cam configuration in which a pair of wheels on the side of the load handling device of the first or second set of wheels is lowered or raised by the same cam and cam follower. However, in a particular embodiment of the present invention shown in FIG. 6, the cam mechanism 152 uses a double cam configuration rather than a single cam configuration on each side of the load handling device. The first cam and the second cam are arranged adjacent to each other in the horizontal direction. The first cam profile and the second cam profile are substantially identical. Similarly, a pair of followers are arranged to engage with their respective cams. Thus, instead of a single cam configuration for raising and lowering a pair of wheels, the double cam configuration on one side of the load handling device provides movement of a pair of wheels on one side of the load handling device in the raised and lowered positions. The use of a double cam configuration rather than a single cam configuration on each side of the load handling device maintains the horizontal orientation of a pair of wheels of the first or second set of wheels when moving in the raised or lowered position. However, the cam mechanism is not limited to a double cam configuration on each side of the load handling device and may comprise a single cam configuration on each side of the load handling device.

[0056] In order to move the cam follower 158 relative to the cam 154, in a particular embodiment of the present invention, the cam mechanism 152 comprises a traveler 164 configured to move along the side of the load handling device. The traveler 164 has a cam follower 158 coupled thereto, whereby movement of the traveler 164 along one side of the load handling device 130 raises and lowers one or more of the wheels of the first set of wheels 134 or the second set of wheels 136. The traveler 164 may be configured to move along rails 166 (see FIG. 8) on each side of the load handling device, whereby movement of the traveler 164 along the rails 166 moves the cam follower 158 along the cam 154, which in turn raises a pair of the wheels of the first or second set of wheels when the cam follower is at the upper limit 162 and lowers one or more wheels when the cam follower is at the lower limit 160 of the cam 154. In a particular example of the present invention, the rails 166 for supporting the traveler 164 are integrally formed from the open frame structure 131 of the load handling device 130.

[0057] The traveler 164 is configured to move along the rail 164 by a cam drive mechanism comprising a cam motor 168 coupled to the traveler 164 via one or more pulleys, spools, belts, and / or gears to move the traveler along one side of the load handling device. In a particular embodiment of the present invention, the motor 168 is configured to move the traveler 164 along one side of the load handling device by a cam belt 170 having one end fixed to the cam motor 168 and the other end fixed to the traveler 164. The cam belt 170 is wound around a cam spool attached to the drive shaft of the cam motor 168, whereby rotation of the cam spool by the cam motor 168 applies a tensile force to the cam belt 170, which in turn moves the traveler 164 fixed to the cam belt 170 along the rail 166. To return the traveler 164 to its initial position, a second motor may apply an opposing tensile force to the traveler 164 to pull the traveler in the opposite direction. Alternatively, the traveler may be biased by a biasing force (e.g., a spring) towards a first position corresponding to the lower or upper limit of the cam profile, and the motor is configured to apply a tensile force to the traveler against the biasing force to move the traveler towards a second position corresponding to the upper or lower limit of the cam profile. Preferably, the cam motor 168 is attached to the open frame structure 131 to provide the anchorage necessary to raise and lower a pair of wheels relative to the open frame structure.

[0058] To provide synchronized movement of the first or second set of wheels moving in the X or Y direction on the grid structure, the corresponding traversers for the first or second set of wheels on opposite sides of the load handling device can be moved by one or more cam motors. For example, a single cam motor can provide a tensile force for raising or lowering the first set of wheels 134. Similarly, a single cam motor can provide a tensile force for raising or lowering the second set of wheels 136. Alternatively, two cam motors can provide opposite tensile forces to the traverser to raise and lower each pair of wheels of the first or second set of wheels. In a specific example of the invention shown in FIG. 6, two cam motors are used to synchronously raise and lower the first and second sets of wheels. To provide synchronized movement of the first set of wheels and the second set of wheels, each of the two cam motors is configured to rotate in both the clockwise and counterclockwise directions. A plurality of cam belts 170 are wound around the outer periphery of the open frame structure 131 of the load handling device 130 via connections to the traverser and the cam motor 168, whereby rotation of the two cam motors in the clockwise direction raises the first set of wheels 134 and lowers the second set of wheels 136. Conversely, rotation of the two cam motors 168 in the counterclockwise direction raises the first set of wheels 134 and lowers the second set of wheels 136.

[0059] A particular example of the wheel positioning mechanism shown in FIG. 6 comprises a cam mechanism driven by a cam motor, although other configurations of the wheel positioning mechanism are also applicable in the present invention. For example, the wheel positioning mechanism may comprise a compliant mechanism having at least one elastically deformable member configured to move under an applied force, such as a motor, to raise or lower the wheels, as taught in PCT application PCT / EP2021 / 055335 in the name of Ocado Innovation, the details of which are incorporated herein by reference. Specifically, the first and second sets of wheels may be raised away from the rails or lowered onto the tracks or rails by a compliant mechanism(s) or set of link mechanisms attached to an open frame structure on opposite faces of the load handling device.

[0060] The direction-changing compliant mechanism is deformable in the first and second directions, respectively. In the absence of an applied force, the compliant mechanism is in a stationary or neutral position, i.e., the compliant mechanism is not elastically deformed and both sets of wheels are at the same height and are placed on the surface. In this configuration, the load handling device cannot move in either the x-direction or the y-direction and the load handling device is stationary. The elastic deformation of the compliant mechanism is linked to an arm that can move in the vertical (or z) direction to hold each of the wheels and raise and lower the wheels.

[0061] When a first input force F1 is applied, the compliant mechanism body deforms in the first direction. The displacement of the mechanism body is converted in the vertical direction to lower the first set of wheels 134 and raise the second set of wheels 136. The wheels of the first set of wheels move downward to engage the rails or tracks to support the vehicle, and the wheels of the second set of wheels move upward away from the tracks. Accordingly, the load handling device 130 can be driven in the X-direction.

[0062] When a force F2 of the second input is applied in a direction opposite to the force of the first input, the compliant mechanism body deforms in the second direction. The displacement of the mechanism body is converted to act in the vertical direction to raise the first set of wheels 134 and lower the second set of wheels 136. As a result, the load handling device can be supported by the second set of wheels 136 and driven in the y direction.

[0063] The compliant mechanism is connected to these sets of wheels 134, 136 via a transmission link mechanism. Thus, in this way, the compliant mechanism provides a means for changing the advancing operation direction of the load handling device 130.

[0064] [Container lifting mechanism] To remove a storage container stored in a grid framework structure, the load handling device includes a container lifting mechanism or a container lifting assembly that includes a grappling device or a container gripping portion assembly for releasably grasping the storage container from the stack and lifting the storage container into the container receiving space of the load handling device. A winch assembly or a crane assembly including a plurality of lifting tethers wound around a separate spool with one end fixed to the grappling device is used to lift and lower the grappling device. The container receiving space is sized to accommodate the dimensions of the storage container. The container receiving space can be within the open frame structure of the load handling device as shown in FIG. 6, or can be adjacent to the open frame structure by a cantilever configuration in a state where the weight of the components housed within the open frame structure balances the weight of the storage container to be lifted by the container lifting mechanism.

[0065] As shown in FIG. 7, the grapple device 170 is formed as a frame having four corner sections, an upper side, and a bottom side. The lifting mechanism is used to lift the container into the container receiving space of the load handling device. For maximum stability and load capacity, typically four lifting tethers 38 (see FIG. 5b) are used to lift the grapple device 170 with one tether disposed near or at each of the corners of the grapple device 170, although different configurations having, for example, fewer tethers may be used as required. One end of each of the tethers, e.g., the first end, is wound onto a spool in the load handling device, and the other end, e.g., the second end, is typically fixed to the grapple device 170 by suitable brackets (not shown) at each corner of the grapple device. The number of tethers attached to the grapple device depends on the ability to keep the grapple device horizontal during operation when picking up the container 10 and the ability to withstand, without stretching or elongation, the tension applied to the tethers when lifting a container that can weigh up to 40 kg, i.e., being inextensible under a given applied tensile stress. To have the required physical properties (Young's modulus), the tethers are generally in the form of cables, e.g., ropes or even tapes, although other tethers having the physical properties necessary to lift the container are also acceptable in the present invention.

[0066] To grasp the container 10, the grapple device 170 includes four positioning pins or guide pins 172 near or at each corner of the grapple device 170 that mate with corresponding notches or holes formed at the four corners of the container 10, and four gripping element 174 disposed on the bottom side of the grapple device 170 for engaging the rim of the container. The positioning pins 172 serve to properly align the gripping elements 174 with corresponding holes in the rim of the container.

[0067] Each of the gripping portion elements 174 includes a pair of wings 176 that are foldable to be receivable in corresponding holes in the rim of the container, and an open expanded configuration having at least one dimension larger than the holes in the rim of the container for engaging the container. The wings 176 can be driven by a drive gear to an open configuration. More specifically, at least one head of the wings includes a plurality of teeth that engage the drive gear, such that when the gripping portion element 174 is actuated, rotation of the drive gear rotates the pair of wings from a folded configuration to an open expanded configuration.

[0068] When in a folded or closed configuration, the gripping portion element 174 is sized to be receivable in the corresponding hole 86 in the rim of the container. Each leg of the pair of wings includes a stop 178, such as a boss, such that when received in the corresponding hole in the rim of the container, the stop engages the lower surface of the rim when in the expanded open configuration and locks onto the container when the grapple device 170 is wound upwardly toward the container receiving portion of the load handling device.

[0069] Moving on to the winch assembly of the container lifting mechanism, the winch assembly comprises a drive mechanism and four tethers wound around four separate spools 180 (see FIG. 6). The four tethers extend downwardly from their respective four spools 180 such that the lower end of each tether is connected to the grappling device 170. The four spools 180 can be attached to separate rotatable or lifting shafts, or alternatively, can be attached to the same or a common rotatable or lifting shaft 182. In a particular embodiment of the invention shown in FIG. 8a, the lifting mechanism includes a central horizontally extending lifting shaft 182 and four spools, with two spools 180 at a first end of the lifting shaft 182 and two spools 180 at a second end of the lifting shaft 182, i.e., the four separate spools carrying the lifting tethers are attached to a single rotatable shaft 182 such that the rotatable shaft is common to all of the four separate spools. As a result, each of the four tethers connected to the grappling device 170 is connected to its own spool such that a single tether is wound onto or unwound from each spool. This advantageously ensures that the wound tether on each spool occupies less space compared to embodiments where two or more tethers are wound onto a single spool. Providing a spool for each tether also advantageously reduces the risk of the tethers becoming entangled when winding and unwinding the tethers to lift and lower the gripping device.

[0070] The lifting shaft 182 is configured to rotate so as to wind up or pay out the tether around each spool. As the lifting shaft rotates in the first rotational direction to wind up the tether, each tether is simultaneously wound around its respective spool so as to lift the grappling device 170 (and the container if being gripped by the grappling device). The lifting shaft 182 is rotated in a second rotational direction (opposite to the first rotational direction) to simultaneously pay out each tether from its respective spool, thereby lowering the grappling device 170 (and the container if being gripped by the grappling device). The tethers are wound up or paid out simultaneously and at the same speed so as to lift or lower the grappling device 170 uniformly and smoothly. The lifting shaft 182 and four pulleys for guiding each of the four lifting tethers to each of the four corners of the grappling device are attached to the open frame structure of the load handling device.

[0071] The lifting assembly includes a motor (not shown) configured to rotate the lifting shaft 182 in the first and second rotational directions so as to wind up or pay out the tethers around their spools. The motor is coupled to the centrally horizontally extending lifting shaft 182 so as to rotate the lifting shaft 182 in the first and second rotational directions. To transmit rotation from the output of the motor to the lifting shaft, various mechanisms including, but not limited to, at least one of a plurality of timing pulleys, timing belts, and / or gears may be used to couple the motor to the lifting shaft. In a particular embodiment of the present invention, the lifting shaft 182 is coupled to the motor via a drive pulley attached to the lifting shaft 182 common to all of the four spools 180 carrying the lifting tethers and a timing belt, whereby rotation of the drive pulley attached to the lifting shaft by connection of the timing belt to the motor drives rotation of all of the four spools common to the lifting shaft.

[0072] The present invention is not limited to the container lifting mechanism described above with reference to FIG. 6, and other container lifting mechanisms for removing storage containers from the grid framework structure of the storage and retrieval system are also applicable in the present invention. For example, the container lifting mechanism may be based on the container lifting mechanism taught in PCT / EP2021 / 051531 in the name of Ocado Innovation Limited, the details of which are incorporated by reference. In PCT / EP2021 / 051531, the container lifting mechanism includes a first set of spools and a second set of spools, where each spool of the first set of spools and the second set of spools carries a lifting tether having a first end fixed to the grappling device and a second end fixed to the spool, and a rotatable shaft. The first set of spools is attached to the rotatable shaft such that the rotatable shaft is common to the first set of spools. A drive pulley and a first set of timing pulleys are attached to the rotatable shaft and are common to the first set of spools, whereby rotation of the rotatable shaft by a single motor connected to the drive pulley drives the first set of spools. A second set of timing pulleys is connected to the first set of timing pulleys via one or more of a plurality of timing belts, whereby rotation of the rotatable shaft by a single motor connected to the drive pulley drives the second set of spools.

[0073] [Open frame structure] Returning to the modular construction of the load handling device to accommodate the different functional features of the load handling device shown in FIG. 8a, the different modular sections 132a, 134a, 136a, 138a of the load handling device can be envisioned by a simplified modular block 132b, 134b, 136b, 138b construction that forms a vertically stacked layered structure shown in FIG. 8b. In a particular embodiment of the present invention, four modular sections 132(a and b), 134(a and b), 136(a and b), 138(a and b) are shown in a vertical stack, and each of the four modular sections provides one or more of the functional features of the load handling device. For the purposes of the description of the present invention, the four modular sections of the load handling device labeled in ascending order of height comprise a first, second, third, and fourth modular section, with the first modular section 132(a and b) being at the bottom of the load handling device and the fourth modular section 138(a and b) being at the top of the load handling device. As shown in FIGS. 8(a and b), each of the four modular sections carries at least a portion of one or more of the functional components of the load handling device. The number and location of the different modular sections within the layered structure are not limited to the four modular sections shown in FIGS. 8(a and b) and may include any number of modular sections that provide additional functional features of the load handling device or may be shared among any number of modular sections.

[0074] Each modular section can be envisioned as a rectangular open frame formed by connecting or joining corner brackets together, where each corner bracket is shown as a connection block in FIG. 8b. The modular section is constructed by connecting adjacent connection blocks in the same horizontal plane by one or more connection elements 184 to form an open rectangular frame 186. Thus, vertically adjacent rectangular frames 186 are connected together by connecting vertically adjacent connection blocks 140, as shown in FIGS. 9(a and b), to form an open frame structure 131. An example of the connection block 140 is a corner bracket. In a single modular section, each corner bracket is connected by one or more connection elements 184 to two other corner brackets in the same horizontal plane. The connection element can be a connecting rod or tube for connecting adjacent connection blocks (corner brackets) together in a single modular section. The connecting rod can be solid or hollow and depends on the connection to the connection block, as further described below. In a particular embodiment of the present invention, the open frame structure is a three-dimensional structure defining a volume having an upper portion for housing a power source 180, a control unit 192, and a spool 182 for carrying a lifting tether, and a lower portion for housing a container receiving space 137.

[0075] The structural integrity of the open frame structure should be sufficient not only to support the different functional features of the load handling device but also to have sufficient bending stiffness when the load handling device is operable on the grid structure. Various materials can be used in the fabrication of the connecting rods or tubes. These include, but are not limited to, metals or polymers or ceramics or combinations thereof. Optionally, the connecting rods that connect adjacent corner brackets together are composed of carbon fibers bonded in a polymer matrix (known as carbon fiber rods) in order to reduce the weight of the load handling device and have the structural properties necessary to support the different functional components of the load handling device. To assist in the construction of the rectangular frame forming the modular section, each of one or more of the connecting blocks of the modular section comprises an opening or socket 187 (see FIGS. 10 and 11) for the insertion of the connecting rod. The connecting rod is fixed to the connecting block by a joint. Various joints can be used to fix the connecting rod to the corner brackets in the modular section. These include various fasteners, adhesives, welding, etc. Further details of the joints that fix the connecting block to the connecting rod are described below.

[0076] The simplified modular section is the case where the connecting block 140 is a corner bracket such that the modular section comprises four corner brackets. Each of the four corner brackets is directly connected to two other corner brackets in the same horizontal plane to form a simple open rectangular frame as shown in FIG. 8b. However, the corner brackets in a single modular section can be indirectly connected to two other corner brackets by one or more connecting blocks intermediate the corner brackets at the corners of the rectangular frame, as illustrated in FIG. 8a. Thus, the term "connected" with respect to the corner brackets in each of the modular sections can be broadly interpreted to mean being directly and / or indirectly connected to two other corner brackets.

[0077] To construct a load handling device according to the present invention, different modular sections are simply connected together by one or more vertical connecting elements 188 via their respective corner brackets 140 to form an open frame structure 131 as shown in the simplified open frame structure in FIGS. 8a and 8b. In other words, the same corner bracket for connecting to two other corner brackets in a single modular section can be used to vertically connect adjacent rectangular frames together. The corner brackets of vertically adjacent rectangular frames can be attached to the same vertical connecting element 188 at each corner of the open frame structure such that the vertical connecting element extends through the corner brackets of a plurality of vertically adjacent rectangular frames. As a result, each corner of the open frame structure shares the same or a common vertical connecting element. To connect a plurality of rectangular frames to the same vertical connecting element at each corner of the open frame structure via their respective corner brackets, the intermediate or corner brackets between the bottom and top rectangular frames have one or more through holes for the vertical connecting element that extends through the corner brackets when connecting vertically adjacent rectangular frames 186 together (see the second modular section in FIG. 8a). This has the advantage that a plurality of rectangular frames 186 can be vertically connected together in a stack simply by attaching the plurality of rectangular frames to the same vertical connecting element at each corner of the open frame structure to form a load handling device as shown in FIGS. 8(a and b). Alternatively, separate vertical connecting elements can be used to connect vertically adjacent rectangular frames at each corner of the open frame structure. The length of the vertical connecting element connecting vertically adjacent rectangular frames determines the height of the load handling device. The connecting element 188 connecting vertically adjacent rectangular frames together can be the same type or a different type of connecting element as the connecting element connecting adjacent corner brackets in the same horizontal plane.For example, the connection element 188 that connects two vertically adjacent rectangular frames together can be a connecting rod used to connect corner brackets in a single modular section. The connection of corner brackets forming a connection block by the horizontal connecting rod 184 and the vertical connecting rod 188 is shown in FIGS. 10 to 12. FIGS. 10 to 12 show the assembly of different modular sections of the load handling device, where FIG. 10 represents the assembly of the first modular section with wheel mounts 139, 141, FIG. 11 represents the assembly of the second modular section with a support or rail 166 for the traveler of the cam mechanism of the wheel positioning mechanism described above, and FIG. 12 is the fourth modular section for supporting the electrical components and power supply of the load handling device. The block construction of the modular sections is shown explicitly in FIGS. 10 to 12, where each corner bracket or connection block 140 includes one or more sockets 187 shaped to receive one or more connecting rods or tubes 184, 188 for connecting the connection blocks together to form a single modular section, and vertically adjacent modular sections are connected together in a vertical stack. The arrows in FIGS. 10 to 12 indicate the direction of the connecting rod or tube 184 when inserted into their respective sockets 187 in the connection block or corner bracket 140.

[0078] In order to simplify the construction of the load handling device while still accommodating different functional features of the load handling device, at least a portion of the functional components of the load handling device is integrated into the open frame structure 131 of the load handling device 130 in the sense that at least a portion of the functional components of the load handling device is integral with one or more of the rectangular frames of the load handling device. For example, at least a portion of the wheel assembly is integral with one or more rectangular frames, at least a portion of the wheel drive assembly is integral with one or more rectangular frames, at least a portion of the wheel positioning mechanism is integral with one or more rectangular frames, and / or at least a portion of the container lifting mechanism is integral with one or more rectangular frames.

[0079] At least a part of different functional features of the load handling device is integrated with one or more of the rectangular frames forming the open frame structure of the load handling device. Therefore, one or more of the connection blocks 140 of one or more of the rectangular frames 186 are manufactured in consideration of the functional features of the load handling device. At least a part of one or more of the functional components of the load handling device is integrated into one or more connection blocks of one or more rectangular frames. For example, one or more of the corner brackets that connect the rectangular frames together may be integrally formed with one or more mounting bases for a spool, a pulley, and / or a motor, rather than having a separate mounting base for attachment to the frame of the load handling device.

[0080] The simplest of the modular sections in a particular embodiment of the present invention is the fourth, i.e., the uppermost, modular section. The rectangular frame 186 of the fourth, i.e., the uppermost, modular section shown in FIG. 6 provides support for electrical components of the load handling device, such as a control unit 192 and / or a power supply 190 for controlling the operation of the wheel drive assembly and / or the wheel positioning mechanism and / or the container lifting mechanism. In a particular embodiment of the present invention, one or more electrical components of the load handling device are supported within one or more cradles 194, which in turn are supported by the rectangular frame. As shown in FIG. 8a, intersecting beams or rods 185 extend across the rectangular frame 186 of the fourth, i.e., the uppermost, modular section to support one or more electrical components of the load handling device. As a result, each of the corner brackets 140 of the rectangular frame of the uppermost modular frame is indirectly connected to two other corner brackets in the same horizontal plane via a connection block located intermediate these corner brackets. Opposing connection blocks located intermediate these corner brackets are joined together to form an intersecting beam or rod extending across the rectangular frame, as shown in FIG. 8a. The rectangular frame of the uppermost modular section is formed by connecting together connection blocks including corner brackets by means of one or more connection elements, as shown in FIG. 12.

[0081] Different connection blocks can be used to construct different modular sections, and the selection of the connection blocks depends largely on the different functional features of the load handling device. The simplest corner brackets or connection blocks 140b are shown in FIG. 13. This is because the rectangular framework of the uppermost modular section provides minimal functionality to the load handling device, except for supporting the power supply and control unit. Here, each of the corner brackets or connection blocks of the uppermost modular section is provided with three openings or sockets 187 (see FIG. 13), two of which are for connecting to two other connection blocks in the same horizontal plane via separate connection elements, and the socket extending downward is for connecting the uppermost modular section to a rectangular frame vertically adjacent in a vertical stack. Since at least a part of the functional components of the load handling device is integrated within the open frame structure, more specifically, within the connection blocks of the open frame structure, the shape of the connection blocks becomes more complex as the complexity of the functional features of the load handling device increases, that is, towards the lower part of the load handling device equipped with a container lifting mechanism, a wheel drive assembly, and a wheel assembly. Examples of various complex connection blocks 140(b~e) forming the corner brackets of the open frame structure are shown in FIGS. 13 to 16, representing different corner brackets for assembling the rectangular frames of different modular sections of the load handling device.

[0082] A variety of lightweight materials can be used in the fabrication of the connection block. Examples of lightweight materials include, but are not limited to, various light metals such as aluminum, or various polymer materials such as plastic materials, or composite materials (e.g., carbon fiber / polymer composites). A variety of methods can be used to fabricate the connection block. These include, but are not limited to, machining from a block, injection molding, or casting. However, as the complexity of the connection block increases, particularly when at least a portion of the functional components of the load handling device are integrated with the connection blocks 140, 140(b - e), more sophisticated fabrication methods can be used. The use of additive manufacturing such as 3D printing provides the ability to fabricate complex connection blocks, whereby at least a portion of the functional components of the load handling device can be integrally formed with one or more connection blocks. The use of additive manufacturing in the fabrication of connection blocks, particularly corner brackets, allows for topology optimization of one or more of the connection blocks in consideration of the stresses that the connection block would experience in an open frame structure. This is because additive manufacturing or 3D printing has the ability to form complex shapes that cannot be achieved by machining alone. This is particularly true when the connection block is topology optimized, as the results of topology optimization tend to result in complex shapes to account for the various load constraints that the connection block would face in its application in the open frame structure of the load handling device.

[0083] The wheels of the wheel assembly are supported by a rectangular frame 186 in the lowermost, i.e., the first modular section. To accommodate the wheels of the wheel assembly, each of the connection blocks in the lowermost, i.e., the first modular section, more specifically, each of the corner brackets, is integrally formed with one or more wheel mounting bases 139, 141 of the first and second sets of wheels. In a particular embodiment of the present invention shown in FIG. 16, each of the corner brackets 140e of the lowermost modular section is formed of two parts to accommodate two wheel mounting bases, i.e., the first and second wheel mounting bases 139, 141. The first wheel mounting base 139 is configured to mount a wheel of the first set of wheels 134, and the second wheel mounting base 141 is configured to mount a wheel of the second set of wheels 136 (thus, there are a total of eight wheels attached to the four corner brackets 140e, with two wheel mounting bases for each of the four corner brackets 140e, and they are arranged to support the open frame structure of the load handling device). In other words, each of the four corner brackets 140e of the first, i.e., the lowermost modular section, is integrally formed with two wheel mounting bases, i.e., the first and second wheel mounting bases 139, 141. To accommodate two wheel mounting bases in one corner bracket 140e, the two wheel mounting bases of a given corner bracket are assembled substantially perpendicular to each other, whereby the first wheel mounting base 139 provides a mounting base for the wheels to move the load handling device in a first direction, and the second wheel mounting base 141 provides a mounting base for moving the load handling device in a substantially vertical direction. In a particular embodiment of the present invention shown in FIGS. 10 and 16, the first and second wheel mounting bases 139, 141 of the corner bracket are provided with a shaft or a spigot for rotatably mounting the respective wheels.

[0084] Also, as shown in FIG. 10 and explicitly shown in FIG. 16, each edge or end of the first and second wheel mounts of a given corner bracket 140e has one or more bosses or fins 196 with apertures that are vertically aligned or concentric to receive a connection element 188 through the apertures of the one or more bosses. One or more bosses 196 at the edges of the first and second wheel mounts 139, 141 are spaced apart such that the bosses 196 of both the first and second wheel mounts of the given corner bracket mesh with each other, and the apertures in their respective bosses are axially aligned along the wheel positioning axis W-W (see FIG. 16) to receive the connection element 188 when the lowermost, i.e., the first modular section, is vertically connected to the second modular section directly above as shown in FIG. 8a. The wheel positioning axis W-W is an axis along which each first set of wheels or second set of wheels is raised or lowered depending on the direction of movement on the grid structure. In FIG. 16, the wheel positioning axis W-W is shown as a vertical axis along which the first and second sets of wheels are raised and lowered. For a given corner bracket, the bosses 196 at the edges of the first and second wheel mounts 139, 141 of the corner bracket 140e are sufficiently spaced apart such that when the spaced bosses mesh with each other, each of the first wheel mount 139 or the second wheel mount 141 of the corner bracket 140e can move independently of the other second wheel mount 141 or the first wheel mount 139 along its vertical connection element, i.e., along the wheel positioning axis W-W. This is to enable a pair of wheels of the first set of wheels to be raised or lowered independently of a pair of wheels of the second set of wheels when the pair of wheels of the first set of wheels is attached to the corner bracket. This is repeated for the other corner brackets of the lowermost modular section, whereby all four corner brackets of the lowermost modular section provide wheel mounts for supporting all of the wheels of the first and second sets of wheels, i.e., eight wheels. Each of the wheel mounts of the corner bracket includes an integrally formed wheel shaft 198 for rotatably mounting the wheel to the shaft.Each corner bracket 140e for attaching the wheel of the wheel assembly is connected by one or more connecting elements 184 to two other corner brackets to form a rectangular frame. In a particular example of the invention shown in FIGS. 8a and 9a, each of the corner brackets 140e is connected by two connecting rods 184 that are receivable in an opening or socket 187 in the corner bracket to two other corner brackets in the same horizontal plane (see FIG. 10). However, the number of connecting elements 184 for connecting adjacent corner brackets in the same horizontal plane to form the rectangular frame of the first modular section comprising the wheel assembly is not limited to two connecting elements and can be any number of connecting elements to provide the necessary structural rigidity of the rectangular frame.

[0085] To drive the rotation of the first and second sets of wheels, at least a portion of the wheel drive assembly described above can be integrated into one or more of the rectangular frames of the open frame structure of the load handling device. When the wheel drive assembly includes a drive belt assembly 140 on each side of the load handling device described above, the mounting bases for the drive wheels and driven wheels for conveying the drive belt can be integrally formed with one or more of the connection blocks 140e (see FIG. 16) of one or more of the rectangular frames. For example, in a particular embodiment of the present invention shown in FIG. 16, each of the corner brackets 140e including wheel mounting bases 139, 141 for the wheel assembly additionally includes a mounting base 198 for the driven wheel 148 of the drive belt assembly, whereby the drive belt moves around the outer circumferences of the wheels 134, 136 attached to the corner bracket 140e and around the driven wheel 148 on the same corner bracket 140e (see FIGS. 6 and 16). Since each corner bracket 140e is integrally formed with two wheel mounting bases 139, 141 for wheels oriented perpendicular to each other to cover the traveling direction of the load handling device on the grid structure, the mounting base 198 for each of their respective driven wheels can be integrally formed with each of the wheel mounting bases 139, 141 of the corner bracket 140e. The drive pulley for driving the drive belt of each wheel drive assembly is attached to the corner bracket 140d of the rectangular frame positioned higher in a vertical stack such that the drive belt extends around a pair of wheels on one side of the load handling device and around the drive wheel attached to the higher modular section. In a particular embodiment of the present invention, the drive wheels for driving the drive belt of each wheel drive assembly are attached to shafts or spigots 202, 204 integrally formed with the corner brackets 140 forming the rectangular frame of the second modular section. As a result, each pair of wheels of the first and second sets of wheels is driven by a drive belt connecting the driven wheel in the first modular section and the drive wheel attached to the corner bracket of the second modular section.As shown in FIG. 6, this is repeated for the other drive assemblies on each side of the load handling device. Also shown in FIG. 6 is that each wheel drive assembly for driving a pair of wheels additionally includes the above-described tension adjustment wheel configuration to ensure that the drive belt around a given pair of wheels remains taut. In a specific example of the load handling device shown in FIG. 6, one or more of the corner brackets of the rectangular frame that supports the wheels also include a wheel tension adjustment configuration.

[0086] The drive assembly is not limited to the drive belt assembly described above, and the connection block of the rectangular frame that supports the wheels of the wheel assembly can be integrated with the mounting base for carrying the above-described hub motor. Accordingly, each corner bracket of the rectangular frame of the first, i.e., the lowermost, modular section can be integrally formed with a mounting base for a drive assembly including a hub motor, where the inner hub of the hub motor is attached to the corner bracket. Since each of the corner brackets of the first, i.e., the lowermost, modular section is formed with two wheel mounting bases for attaching two wheels, each corner bracket is integrally formed with two mounting bases for attaching two hub motors, one for attaching a wheel in a first direction and the other for attaching a wheel in a second direction.

[0087] To change direction on the grid structure, the load handling device comprises a wheel positioning mechanism. Various wheel positioning mechanisms are known in the art, some of which are described above. Considering that sufficient force is required to lift a pair of wheels out of a given set of wheels perpendicular to the open frame structure, at least a portion of the wheel positioning mechanism is attached to a rectangular frame of the open frame structure reinforced to support the weight of the pair of wheels on each side of the load handling device. In a particular example of the load handling device shown in FIGS. 6 and 11, the rectangular frame of the second modular section is reinforced by one or more struts or braces 206, which is located substantially in the middle of the height of the load handling device and is thus called a "middle halo". The reinforcement of the middle halo is provided by one or more cross braces 206 extending across the rectangular frame. A particular example of the wheel positioning mechanism shown in FIG. 6 is based on the above-described cam mechanism comprising a cam, a cam follower movable along the cam, and a traveler for moving the cam follower. The traveler is configured to move along a rail 166 on one side of the load handling device to raise a pair of wheels. The rail 166 for supporting the traveler for raising a pair of wheels comprises a horizontal connecting element extending between corner brackets of the rectangular frame of the middle halo such that the traveler moves along a connecting element 184 connecting a corner bracket on one side of the load handling device. Thus, the connecting element for supporting the traveler of the middle halo functions as an overhead rail. In a particular example of the invention shown in FIG. 6, the traveler is slidably attached to a connecting element connecting corner brackets in the same horizontal plane. This is repeated for the other pairs of wheels on each side of the load handling device. To support the traveler, at least two connecting elements 184 extend between corner brackets 140 on one side of the load handling device.One or more inserts 208 are sandwiched between two connection elements 184 extending between corner brackets 140 to impart bending stiffness to the connection elements extending between the corner brackets 140 to prevent the connection elements from bending excessively when the traveler moves along the connection elements. In a particular example of the present invention, the cam mechanism for each of the pair of wheels of the first and second sets of wheels is based on a double-cam configuration as described above, where the traveler is configured to raise and lower a predetermined pair of wheels via the double-cam configuration. The cam for cooperating with the cam follower can be attached to the corner bracket supporting the wheel of the wheel assembly or can be integrally formed with the corner bracket. In the double-cam configuration on each side of the load handling device, two cams cooperating with two respective cam followers are attached to each corner bracket to cater for the vertical movement of the wheels oriented in the first and second directions (see FIG. 15). Thus, for a given corner bracket, the first cam is attached to or integrally formed with the first wheel mounting base of the corner bracket, and the second cam is attached to or integrally formed with the second wheel mounting base of the corner bracket, such that when the first and second wheel mounting bases of the corner bracket are brought together, the cams on different sides of the load handling device cooperate with their respective cam followers. Similar corner brackets are also used to attach the other wheels of the wheel assembly.

[0088] As the cam follower moves along the cam, an upward or downward force is applied to each corner bracket carrying a wheel of the first or second set of wheels, which raises or lowers the wheels depending on the direction of travel of the load handling device on the grid structure. As described above, each corner bracket for attaching the wheels of the wheel assembly is formed from two intermeshing parts, namely a first part 139 and a second part 141, each of the first and second parts comprising a wheel mounting platform for the wheel. The first part provides a wheel mounting platform for the wheels of the first set of wheels, and the second part provides a wheel mounting platform for the wheels of the second set of wheels, defined as the first wheel mounting platform 139 and the second wheel mounting platform 141 respectively. The bosses or fingers 196 at the edges of the first and second wheel mounting platforms are sufficiently spaced such that when the bosses intermesh, the first wheel mounting platform can move axially along its connecting vertical connecting element independently of the second wheel mounting platform. When the vertical connecting element is a connecting rod, the diameter of the openings in one or more bosses of each of the first and second wheel mounting platforms of the corner bracket is slightly larger than the diameter of the connecting rod 188, thereby enabling the first and second wheel mounting platforms 139, 141 of the corner bracket to move vertically when a force is applied in the vertical direction. The cam 154 cooperating with the cam follower 158 can be integrally formed with its respective corner bracket 140e comprising the wheel mounting platform of the wheel assembly, as shown in FIG. 16. Two cams 154 are shown integrally formed with the corner bracket 140e, one for each of the wheel mounting platforms 139, 141. As can be understood from the above description in relation to FIGS. 6 and 16, at least a portion of the wheel positioning mechanism forms one or more rectangular frame connection blocks forming different modular sections of the load handling device, more specifically, is integrally formed with the corner bracket.

[0089] Also, FIG. 6 shows that a motor for moving the traverser along the connecting element is attached to a corner bracket 140d of a rectangular frame forming an intermediate halo of an open frame structure. One or more mounting bases for one or more motors are integrally formed with a connection block, more specifically, a corner bracket of the rectangular frame of the intermediate halo. As shown in FIG. 15, one or more openings 210 are integrally formed in the corner bracket 140d for receiving the motor shaft of the motor. The corner bracket 140d also supports a spool for winding a belt connected to the traverser as the spool rotates, such that when the motor rotates in the clockwise direction, the belt is wound onto the spool, and when the motor rotates in the counterclockwise direction, the belt is unwound from the spool.

[0090] In addition to at least a portion of the wheel positioning mechanism being integrally formed with a connection block or corner bracket forming a rectangular frame of one or more modular sections, at least a portion of the container lifting mechanism, more specifically, the winch assembly, is integrally formed with the rectangular frame of one or more modular sections. The lifting shaft for driving the rotation of the four spools carrying the lifting tethers connected to the grappling device is rotatably mounted to the rectangular frame of the modular section. In the example shown in FIG. 8a, the lifting shaft 182 is rotatably mounted to the rectangular frame of the third modular section. FIGS. 8a and 9a show the lifting shaft 182 extending across the rectangular frame. Opposite ends of the lifting shaft are rotatably mounted to connection elements connecting adjacent corner brackets via respective connection blocks 212. The four lifting pulleys 214 of the container lifting mechanism are one each at each corner of the lifting assembly for guiding the lifting tethers to respective corners of the grappling device and are respectively attached to respective corner brackets 140c of the rectangular frame (see FIG. 14). Accordingly, each tether extending from each spool around each pulley extends downward and connects to the grappling device, e.g., to a corner of the grappling device. The mounting bases for the four pulleys 214 may be integrated with respective corner brackets 140c of the rectangular frame.

[0091] In certain embodiments of the present invention, a container receiving space 137 (see FIG. 9a) for receiving a storage container when lifted by a grapple device is located within the open frame structure of the load handling device, and more specifically, within the area of the first, second, and third modular sections (the third modular section supports a spool carrying a lifting tether). However, since the vertically adjacent modular sections are connected together by their respective connection blocks via vertical connection rods, it is necessary to guide the grapple device when it is lifted and lowered in and out of the container receiving space to prevent the grapple device from fouling the connection blocks. In certain embodiments of the present invention, downwardly extending guides (not shown) are attached to the connection blocks 140c of the second modular section of the load handling device, one at each corner of the rectangular frame, thereby guiding the grapple device as it is lowered or raised into the container receiving space. Each of the guides is shaped to include two vertical guide plates for receiving the corners of the grapple device shown in FIG. 7.

[0092] The container lifting mechanism is configured to lift and lower a storage container that can have a weight of up to 40 kg. Therefore, the connection elements extending between the corner brackets can be braced by one or more bracing elements 216 to strengthen the rectangular frame of the modular section that supports the spool carrying the lifting tether. In the specific example shown in FIGS. 8a and 9a, two bracing elements 216 are shown bracing the connection elements extending between the corner brackets on opposite sides of the load handling device. The opposing ends of the bracing elements are attached to the connection elements by connection blocks 218.

[0093] A plurality of rectangular frames 186 are assembled together in a vertical stack to provide different functional features of the payload handling device described above. Adjacent rectangular frames vertically are connected together by vertical connecting elements 188 to form an open frame structure 131 that supports different functional features of the payload handling device. FIGS. 10 - 12 show examples of assembling connection blocks together by connection rods to form the rectangular frames of the first, second, and fourth modular sections, respectively. Preferably, each of the connection blocks (corner brackets) 140 at the corners of the plurality of rectangular frames is connected or joined together in a vertical stack by one or more vertical connecting elements or rods 188. A vertical connecting rod for connecting adjacent rectangular frames vertically is shown in FIG. 11. The vertical connecting rod is shown fixed to a connection block (corner bracket) at the corner of the rectangular frame. To connect the connection blocks together with the connecting rod, the connection block includes one or more openings or sockets 187 for receiving the ends of the connecting rod. The manufacture of the payload handling device involves inserting the ends of the connecting rod into the openings or sockets of the connection block to connect the connection blocks together. To help reduce the weight of the payload handling device according to the present invention, the connecting rod is typically hollow, for example, a hollow pipe. Jigs can be used to assemble the individual rectangular frames together, while the connections between the connection blocks and / or corner brackets and the connecting elements are fixed by suitable joints.

[0094] During operation of the load handling device on the grid structure, the stress received by the open frame structure concentrates around the joint between the connection block and the connection rod. If the connection rod is not properly fixed to the connection block, one or more of the connection rods may become detached from their corresponding connection block, resulting in the final failure of the rectangular frame associated with that connection block and, in the worst case, the failure of the open frame structure. To ensure the structural integrity of the resulting open frame structure, the joint for fixing the end of the connection rod to the connection block should have sufficient strength to prevent the end of the connection rod from becoming detached from the connection block, more specifically, from the socket 187 in the connection block. Various joints can be used to fix the end of the connection rod to the connection block, which depends largely on the materials used in the manufacture of the connection block and the connection rod. The various joints can include, but are not limited to, gluing or welding.

[0095] [Joint] When one or more of the connection blocks of the open frame structure operate as a load handling device on the grid structure, the topology can be optimized to accommodate different loads or stresses that the open frame structure experiences. Meanwhile, the joints between connection block 140 and connection elements 184, 188, such as connection rods, must also have sufficient strength to withstand the forces experienced when the load handling device operates on the grid structure. Such forces include the force to pull out the connection rod from socket 187 of the connection block, as well as bending and torsional forces when the connection element is subjected to a bending moment. Various techniques can be used to fix the connection block to the connection element. These include the use of adhesives or glue, fasteners or welding, or any combination of these methods. Using an adhesive to fix the connection block to the connection element seems to be the most efficient and cost-effective way to assemble an open frame work structure with connection blocks connected together by multiple connection elements. However, since a load handling device operable on a grid frame work structure is subject to many forces such as bending and torsional forces that result in a bending moment at the joint between the connection block and the connection element, the joint between the connection block and the connection element must have sufficient strength to prevent the connection element, usually in the form of a rod, from detaching from the connection block. While various commercially available adhesives have the adhesive strength required to fix the connection element to the connection block, the ability of the adhesive to provide a secure connection between the connection block and the connection element depends largely on the surface contact area of the adhesive between connection block 140 and connection elements 184, 188. The larger the contact surface area of the adhesive between the connection block and the connection element, the more adhesive can contribute to the adhesive strength between the connection block and the connection element, thus increasing the adhesive strength.

[0096] When the connecting element is a rod and the rod is inserted into an opening or socket 187 integrally formed within the connection block 140, the adhesion strength between the rod and the socket having an inner wall highly depends on the spread of the adhesive along the connecting end of the rod. Simply coating one end of the rod with the adhesive and inserting the rod into the socket 187 of the connection block 140 has the problem that since the socket is a blind hole and adhesive accumulates at the entrance of the socket, excess adhesive can be extruded from the entrance of the socket. This is unsightly and can cause other deformations in an assembly with a connection block, for example, in the open frame structure described above. Next, coating the connecting end of the connecting element is not suitable for assembling a plurality of connection blocks with the connecting element before fixing or adhering the connection block to the connecting element with the adhesive. This is especially true when a plurality of connection blocks and connecting elements are assembled with jigs to ensure that the connection blocks are accurately aligned with the rod in the assembly. This problem worsens when the adhesive used to fix the connection block to the connecting element has a relatively short curing time after being applied. This problem is not limited to only the connection blocks during the fabrication of the open frame structure that supports the components providing the functional features of the load handling device described above, and this problem can also exist when connecting any type of connection block to a connecting element such as a rod.

[0097] Therefore, there is a need for a joint that can fix the connection block to the rod without suffering from the above-described drawbacks. In the present invention, an adhesive in the form of a fluid is preferably spread along the connection end of the rod after or subsequent to the connection end of the rod being inserted into the socket of the connection block. This enables a plurality of connection blocks to be assembled with their respective rods before the rods are adhered or fixed to their respective connection blocks, and thus enables the use of jigs to control the accuracy or precision of the alignment of the connection blocks with their respective rods. In an example of the present invention, the inner wall of the socket comprises a groove extending around at least a portion of the inner wall of the socket for distributing the adhesive along the connection end of the rod. The connection block comprises an inlet having an inlet opening outside the connection block and in fluid communication with the groove for injecting the adhesive into the groove, and the groove is configured to form an adhesive channel when the connection end of the rod is inserted into the socket, whereby when the adhesive is injected into the inlet opening, the adhesive flows along the adhesive channel around the outer surface of the connection end of the rod. Different shaped grooves can be formed within the inner wall of the socket. An efficient way to distribute the adhesive along the connection end of the rod is to provide a continuous groove extending axially along at least a portion of the length of the socket and to provide a continuous adhesive channel in fluid communication with the inlet opening when the connection end of the rod is inserted into the socket.

[0098] An example of providing a continuous groove is a helical groove or a spiral groove formed within the inner wall of the socket, which results in an adhesive channel 220 having a helical or spiral shape. An example of a helical or spiral adhesive channel 220 extending axially along at least a portion of the longitudinal length of the socket is shown in FIG. 17. The spiral or helical adhesive channel 220 enables the adhesive to be distributed or spread axially along the connection end portion of the rod. Also shown in FIG. 17 is an inlet 222 for supplying the adhesive to the spiral adhesive channel 220. The inlet comprises an inlet path 224 that is in fluid communication with the spiral adhesive channel 220 and extends from the opening 226 of the inlet 222 to the spiral adhesive channel 220. The opening 226 is formed in at least one outer wall of the connection block such that the adhesive can be supplied to the channel from outside the connection block. This has the advantage that the adhesive can be supplied to the channel after the rod has been inserted into the socket of the connection block, which enables a plurality of connection blocks to be assembled together with a jig before each of the plurality of connection blocks is adhered to its respective connection element.

[0099] Different adhesives have different viscosities and curing times. To accommodate different adhesives with different viscosities and curing times that are injected into the glue channel, the rate of flow of the adhesive through the glue channel is controlled. A flow rate that is too low can result in the adhesive curing prematurely before filling the glue channel, and a flow rate that is too high can result in the adhesive leaking out of the glue channel before it cures. To control the flow rate of the adhesive through the glue channel, the inlet path 224 extending from the inlet opening 226 to the glue channel 220 is tapered or has diverging walls to create a Venturi effect such that there is a pressure difference between the pressure at the inlet opening 226 and the pressure at the inlet of the glue channel 220. By controlling the divergence of the inlet path 224, this pressure difference can be controlled and thus the flow rate of the adhesive through the glue channel can be controlled. In the specific example shown in FIG. 17, the inlet path 224 diverges such that the inlet path contracts as it approaches the inlet of the glue channel 220, resulting in a higher flow rate at the inlet of the glue channel. Although not shown in FIG. 17, the connection block may optionally include an outlet with an outlet path extending from an outlet opening external to the connection block, whereby excess adhesive can exit the glue channel through the outlet opening. The adhesive exiting the outlet opening provides an indication that the adhesive has sufficiently filled the glue channel and that the bonding process is complete.

[0100] However, according to the present invention, there are other examples of distributing an adhesive along the connection end of the rod when inserted into the socket to ensure good adhesion between the rod and the connection block. In another example of the glue channel shown in FIGS. 18(a and b), the groove comprises a plurality of separate circular grooves spaced along the axial length of the socket, which provides a plurality of spaced or separate circular glue channels 228 for distributing the adhesive across the connection end of the rod. To supply the adhesive to each of the plurality of circular glue channels, the inlet 322 comprises a plurality of inlet paths 330 branched from a single inlet opening 326 as shown in FIGS. 18(a and b). Each of the plurality of inlet paths 330 supplies each of the plurality of spaced circular glue channels 228. This enables the adhesive to be supplied to each of the plurality of circular glue channels 228 through a single injection of the adhesive into the inlet opening 326 of the inlet 322. This is illustrated in the schematic view of the plurality of circular glue channels in FIG. 18b. The number and spacing of the circular grooves, and thus the circular glue channels 228, control the amount of adhesive deposited on the outer surface of the connection end of the rod between the inner wall of the socket and the connection end of the rod when the rod is inserted into the socket.

[0101] Also shown in FIGS. 18(a and b) is an outlet 332 having a common outlet path 334 for the plurality of circular glue channels 228 in the sense that it is in fluid communication with the plurality of circular glue channels 228. As described above, the outlet 332 provides an indication that the adhesive has filled the plurality of circular glue channels 228. The outlet path 334 is positioned such that the adhesive flows through the plurality of glue channels 228 before exiting from the outlet opening 336. The outlet path 334 is shown extending to a single outlet opening 336 across the plurality of circular glue channels 228 such that the outlet path 334 is shared between the plurality of circular glue channels 228.

[0102] The use of lightweight materials such as plastics helps to reduce the weight of the assembly of the connection block and the connection element, for example, of the open frame structure described above. However, the use of lightweight connection elements also helps to reduce the weight of the assembly. An example of a lightweight connection element is a hollow rod. However, the use of hollow rods has several drawbacks as connection elements. One of the main drawbacks is the risk that the hollow rod may collapse as a result of the stress at the inlet of the socket. When the connection between the connection block and the rod relies on the rod being inserted into the socket in the connection block, there is a stress concentration region around the vicinity of the inlet of the socket. This is particularly the case in the region at the inlet of the socket having a relatively sharp edge 232 as shown in FIG. 19 where the shape of the wall of the socket changes abruptly. The bending moment received by the rod concentrates around the region around the inlet of the socket, particularly at the edge 232 of the socket 187, with the risk that the edge of the socket impinges against the wall of the rod 184. Without internal support, there is a risk that the rod 184 may bend and, in the worst case, collapse due to the stress concentrated at the edge 232 of the socket 187.

[0103] To mitigate this problem, as shown in FIG. 19, an insert 234 that is receivable in the hollow portion of the rod 184 is provided in the socket 187 so as to provide internal support when the connecting end portion of the rod is inserted into the socket of the connection block. The insert shown in FIG. 19 has an axis X-X that is concentric with the longitudinal axis of the socket and extends axially along at least a portion of the longitudinal length of the socket. Introducing the insert 234 into the socket 187 of the connection block also results in further manufacturing complexity for including glue channels in the socket. The use of additive manufacturing or 3D printing in the fabrication of the connection block provides an opportunity to integrally form complex shapes inside the connection block.

[0104] To provide a secure adhesion between the rod and the connection block, glue channels are formed around the inner wall of the socket and the outer surface of the insert. In a particular embodiment of the present invention, as shown in the example of the present invention shown in FIG. 19, a groove is formed around the inner wall of the socket to form a first glue channel 420a when the rod is inserted into the socket, and a groove is formed around the outer periphery or surface of the insert to form a second glue channel 420b when the rod is inserted into the socket. Due to the positions of the first groove on the inner wall of the socket and the second groove on the outer surface of the insert, the first glue channel 420a is shown in FIG. 19 as being opposed to the second glue channel 420b. Thus, both the outer and inner surfaces of the connection end portion of the rod are adhered to the inner wall of the socket and the outer surface of the insert, respectively (see FIG. 19). To prevent air from accumulating inside the rod when the rod is inserted into the socket 187, a vent hole 424 can be incorporated into the insert. The vent hole 424 is a through hole that extends from the insert to the outside of the connection block so as to allow air to escape from inside the rod when the rod is inserted into the socket.

[0105] When socket 187 includes insert 234, in one example of the present invention, to supply adhesive to first and second glue channels 420a, 420b from a single injection point, the inlet path from inlet opening 426 external to the connection block comprises a plurality of inlet paths 430a, 430b that branch from a single inlet opening 426 such that the longitudinal axis A-A of the second glue channel 420b is concentric with the longitudinal axis of the first glue channel 420a. An example of providing the first and second glue channels 420a, 420b is shown in FIGS. 20(a and b), which shows the arrangement of the spiral-shaped glue channels for the first and second glue channels 430a, 430b. Each of the first and second glue channels can be supplied with adhesive by the first and second inlets, where each of the first and second inlets is supplied from a separate inlet opening. Alternatively, the first and second glue channels 420a, 420b can be supplied from a single inlet opening 426 that branches into a plurality of inlet paths 430a, 430b, each of these plurality of paths supplying the respective first and second glue channels 420a, 420b. The inlets shown in FIGS. 20(a and b) comprise first and second inlet paths 430a, 430b in fluid communication with the first and second glue channels 420a, 420b, which are supplied from a single or common inlet opening 426 external to the connection block. Each of the first and second inlet paths 430a, 430b branches from the inlet opening 426 to the respective first and second glue channels 420a, 420b. Each of the first and second glue channels 420a, 420b can comprise a separate outlet to provide an indication that their respective first and second glue channels are filled with adhesive. Alternatively, as described above, a common outlet can be provided for both the first and second glue channels.

[0106] Figures 21(a and b) show another example of providing first and second glue channels for supplying adhesive to the inner wall of the socket and the outer surface of the insert, respectively. In the arrangement of the glue channels in the example shown in Figures 21(a and b), the glue channels for supplying adhesive to the inner wall of the socket and the outer surface of the insert are based on a combination of a separate circular ring 520b and the spiral type 520a described above with reference to Figures 17 and 18(a and b). In the specific example shown in Figures 21(a and b), the groove formed in the inner wall of the socket cooperates with the outer surface of the connecting end portion of the rod to form a separate circular glue channel 520a, and the groove on the outer surface of the insert cooperates with the inner surface of the connecting rod to form a spiral-shaped glue channel 520b. Having a combination of a separate circular glue channel on the outer surface of the rod and a spiral glue channel on the inner surface of the rod enables both types of glue channels to be supplied with adhesive by a single injection of adhesive into the inlet 522. To accommodate supplying adhesive to different-shaped glue channels, the inlet 522 includes a plurality of inlet paths 530a that branch off to supply adhesive to the separate circular glue channel of the first glue channel 520a outside the rod, as shown in Figure 21a, and a single inlet path 530b for supplying adhesive to the spiral glue channel of the second glue channel 520b inside the rod. However, different arrangements of the glue channels for supplying adhesive to the outer surface and the inner surface of the rod are applicable in the present invention and may include the different arrangements of the glue channels described above with reference to Figures 17 and 18(a and b). Also, Figures 21a and 21b show an outlet 532 in fluid communication with the first and second glue channels 520a, 520b to provide an indication that the respective first and second glue channels 520a, 520b are filled.

[0107] The glue channels of certain examples are formed by incorporating grooves in the inner wall of the socket, as shown in FIGS. 17-21(a and b), although the glue channels can be formed by providing grooves in the connecting end of the rod such that when the connecting end of the rod is inserted into the socket, glue can be injected into the glue channel from an inlet having an inlet opening that is outside the connection block and in fluid communication with the glue channel. The inlet path is positioned in the connection block to direct the glue to one or more grooves at the connecting end of the rod. As the glue moves around the grooves at the connecting end of the rod, the glue is distributed along the connecting end of the rod inserted into the socket. When cured, the glue forms a joint between the inner wall of the socket and the connecting end of the rod.

[0108] The advantage of injecting the glue through an inlet opening outside the connection block is the ability to assemble multiple connection blocks and connecting rods with a jig and ensure that the assembly is accurately positioned before the glue is injected into the inlet opening. Having different shaped glue channels inside the socket for receiving the connecting end of the rod ensures that the glue spreads along the connecting end of the rod to provide good adhesion between the connection block and the rod. The ability to have different shaped glue channels inside the socket is possible because the connection block can be manufactured by additive manufacturing or 3D printing that allows for complex shapes to be incorporated internally within the connection block.

Claims

Claim 1 A load handling device for lifting and moving one or more stackable containers in a storage and retrieval system, wherein the storage and retrieval system comprises a grid structure comprising a plurality of grid members comprising a first set of grid members and a second set of grid members, the second set of grid members being substantially perpendicular to the first set of grid members, whereby the plurality of grid members are arranged in a grid pattern for guiding the movement of the load handling device on the grid structure, the load handling device comprising a plurality of modular sections arranged in a vertical stack, the plurality of modular sections comprising a) a container lifting mechanism comprising a grappling device configured to releasably grip a container and a drive mechanism configured to raise and lower the grappling device; b) a first set of wheels for engaging a first set of grid members for guiding movement of the load handling device in a first direction and a second set of wheels for engaging a second set of grid members for guiding movement of the load handling device in a second direction, wherein the second direction intersects the first direction; c) a wheel positioning mechanism configured to selectively lower or raise the first set of wheels or the second set of wheels so as to engage or disengage from the first set of grid members or the second set of grid members; d) an electrical component comprising a processor for controlling the container lifting mechanism and the wheel positioning mechanism; and comprising Each of the plurality of modular sections further comprises at least four connection blocks, and each of the at least four connection blocks is connected to two other connection blocks in a single modular section by one or more substantially horizontal connection elements to form a rectangular frame, and the at least four connection blocks of vertically adjacent modular sections are connectable in the vertical stack by one or more substantially vertical connection elements to form an open frame structure comprising a plurality of the rectangular frames, and the open frame structure is configured to support the container lifting mechanism, the wheel assembly, the wheel positioning mechanism, and the electrical components, a cargo handling device.

2. The cargo handling device according to claim 1, wherein the at least four connection blocks comprise four corner brackets, and each corner bracket of the four corner brackets is connected to two other corner brackets in a single modular frame to form the rectangular frame.

3. The cargo handling device according to claim 1 or 2, wherein one or more of the horizontal connection elements and / or the vertical connection elements comprise connection rods or tubes.

4. The cargo handling device according to claim 3, wherein one or more of the at least four connection blocks comprise sockets for receiving ends of the connection rods or tubes.

5. The socket has a substantially cylindrical inner wall, and the cylindrical inner wall has a groove continuously extending around at least a portion of the cylindrical inner wall of the socket for axially distributing an adhesive along the receiving side end of the rod, and the groove is configured to form an adhesive channel when the receiving side end of the connection rod is inserted into the socket. The cargo handling device according to claim 4.

6. The cargo handling device according to claim 5, wherein one or more of the at least four connection blocks comprise one or more injection points in fluid communication with the groove for injecting an adhesive into the adhesive channel.

7. The loading handling device according to any one of claims 1 to 6, wherein one or more of the plurality of modular sections are braced by one or more bracing elements extending between opposing horizontal connecting elements of the rectangular frame.

8. The loading handling device according to any one of claims 1 to 7, wherein the one or more vertical connecting elements extend vertically through one or more of the at least four connection blocks of the rectangular frames vertically adjacent in the vertical stack.

9. The loading handling device according to any one of claims 1 to 8, wherein one or more of the at least four connection blocks of one or more of the plurality of modular sections are formed from a polymer.

10. The loading handling device according to any one of claims 1 to 9, wherein the open frame structure defines a volume for accommodating a container receiving space.

11. The loading handling device according to any one of claims 1 to 10, wherein one or more of the at least four connection blocks of one or more of the plurality of modular sections comprise one or more mounting bases for pulleys.

12. The loading handling device according to any one of claims 1 to 11, wherein one or more of the at least four connection blocks of one or more of the plurality of modular sections comprise one or more mounting bases for motors.

13. The loading handling device according to any one of claims 1 to 12, wherein one or more of the at least four connection blocks of one or more of the plurality of modular sections comprise at least a portion of the container lifting mechanism and / or the wheel assembly and / or the wheel positioning mechanism and / or the electrical components.

14. The loading handling device according to claim 13, wherein at least a portion of the container lifting mechanism and / or the wheel assembly and / or the wheel positioning mechanism and / or the electrical components are integrally formed with one or more of the at least four connection blocks of one or more of the plurality of modular sections.

15. The loading handling device according to claim 14, wherein each wheel of the wheel assembly is mounted to a wheel mounting base.

16. The load handling device according to claim 15, wherein the wheel mounting base is integrally formed with a connection block of a predetermined modular section.

17. The load handling device according to claim 15 or 16, wherein the connection block of the predetermined modular section includes a first wheel mounting base for a wheel among the first set of wheels and a second wheel mounting base for a wheel among the second set of wheels.

18. The first wheel mounting base and the second wheel mounting base include a plurality of bosses along the edges of the first wheel mounting base and the second wheel mounting base. Each of the plurality of bosses of the first wheel mounting base and the second wheel mounting base includes an opening axially aligned along a wheel positioning axis. The wheel positioning axis is an axis along which each of the first set of wheels or the second set of wheels is raised and lowered. The plurality of bosses of the first wheel mounting base and the second wheel mounting base are spaced apart such that the plurality of bosses of the first wheel mounting base and the second wheel mounting base mesh with each other, and the openings in each of the meshed bosses of the first wheel mounting base and the second wheel mounting base are axially aligned along the wheel positioning axis to receive the vertical connecting element through their respective openings. The spacing between the bosses of the first wheel mounting base and the second wheel mounting base is sufficiently large to allow the first wheel mounting base to move independently of the second wheel mounting base along the wheel positioning axis. The load handling device according to claim 17.

19. The load handling device according to any one of claims 1 to 18, wherein the wheel positioning mechanism includes a cam mechanism, and one or more of the at least four connection blocks among one or more of the plurality of modular sections include at least a part of the cam mechanism.

20. The load handling device according to claim 19, wherein at least a part of the cam mechanism is integrally formed with one or more of the at least four connection blocks among one or more of the plurality of modular sections.

21. The container lifting mechanism is a) a first set of spools and a second set of spools, wherein each spool of the first set of spools and the second set of spools carries a lifting tether having a first end fixed to the container gripping assembly and a second end fixed to the spool; b) a rotatable shaft, wherein the first set of spools and / or the second set of spools are attached to the rotatable shaft such that the rotatable shaft is common to the first set of spools and / or the second set of spools; c) a drive mechanism comprising a drive pulley attached to the rotatable shaft common to the first set of spools and / or the second set of spools such that rotation of the rotatable shaft by the drive pulley drives rotation of the first set of spools and / or the second set of spools; The load handling device according to any one of claims 1 to 20, comprising the above.

22. The load handling device according to claim 21, wherein the rotatable shaft is attached to the one or more horizontal connecting elements connecting two adjacent connecting blocks.

23. The load handling device according to any one of claims 1 to 22, wherein any one of the container lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism, and / or the electrical components is shared between two or more of the plurality of modular sections.

24. The load handling device according to any one of claims 1 to 23, wherein a plurality of vertically adjacent rectangular frames define a volume for accommodating at least a portion of the container lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism, and / or the electrical components.

25. The load handling device according to any one of claims 1 to 24, wherein the plurality of modular sections in ascending order of the height of the load handling device comprise a first modular section, a second modular section, a third modular section, and a fourth modular section, the first modular section being at the bottom of the load handling device and the fourth modular section being at the top of the load handling device.

26. The load handling device according to claim 25, wherein the first modular section includes the wheel assembly.

27. The load handling device according to claim 25 or 26, wherein the fourth modular section includes one or more cradles for supporting the electrical components.

28. The load handling device according to claim 27, wherein the one or more cradles are attached to one or more of the horizontal connecting elements that connect two adjacent connection blocks of the fourth modular section.

29. The load handling device according to any one of claims 1 to 28, wherein one or more of the plurality of rectangular frames and one or more of the connection blocks are integrally formed as a single unit.

30. A method of constructing a load handling device, comprising: i) forming a rectangular frame by connecting at least four connection blocks together by one or more horizontal connecting elements; ii) connecting a plurality of rectangular frames together in a vertical stack by connecting the connection blocks of vertically adjacent rectangular frames by one or more vertical connecting elements to form an open frame structure, wherein the open frame structure supports: a) a container lifting mechanism comprising a grappling device configured to releasably grip a container and a drive mechanism configured to raise and lower the grappling device; b) a wheel assembly disposed to support a vehicle body, wherein the wheel assembly includes a first set of wheels for engaging a first set of grid members for guiding movement of the load handling device in a first direction and a second set of wheels for engaging a second set of grid members for guiding movement of the load handling device in a second direction, the second direction being transverse to the first direction, and each wheel of the first set of wheels and the second set of wheels is attached to a wheel mounting base; c) a wheel positioning mechanism configured to selectively lower or raise the first set of wheels or the second set of wheels to engage or disengage with the first set of grid members or the second set of grid members; d) electrical components including a processor for controlling the lifting mechanism and the wheel positioning mechanism. A method.

31. The method according to claim 30, wherein the open frame structure is formed by inserting one or more of the plurality of horizontal connection elements and / or the vertical connection elements into openings in one or more of the at least four connection blocks.

32. The method according to claim 30 or 31, further comprising the step of attaching at least a part of the container lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism, and / or the electrical components to the open frame structure.

33. The method according to any one of claims 30 to 32, further comprising the step of integrally forming at least a part of the container lifting mechanism, and / or the wheel assembly, and / or the wheel positioning mechanism from one or more of the at least four connection blocks of the open frame structure.

34. The method according to any one of claims 30 to 33, further comprising the step of additive manufacturing or 3D printing one or more of the at least four connection blocks of one or more of the plurality of rectangular frames of the open frame structure.

35. The method according to any one of claims 30 to 34, further comprising the step of assembling one or more of the plurality of rectangular frames with a jig so that the at least four connection blocks are connected to their respective horizontal connection elements.

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