A method of assembling a frame structure

Abstract

A method of assembling a frame structure comprising a plurality of connecting blocks 46 connectable together by a plurality of connecting elements 48 is disclosed. Each of the plurality of connecting

Description

Field of Invention The present invention relates to a method of assembling a frame structure to a tight dimensional tolerance. In particular, but not exclusively, the invention relates to a frame structure for a robotic load handling device for handling storage containers in a storage and retrieval system comprising a grid framework structure. Background Storage and retrieval systems 1 comprising a three-dimensional storage grid framework structure, within which storage containers / bins are stacked on top of each other, are well known. PCT Publication No. WO2015 / 185628A (Ocado) describes a known storage and fulfilment or distribution system in which stacks of bins or containers are arranged within a grid framework structure. The bins or containers are accessed by load handling devices remotely operative on tracks located on the top of the grid framework structure. A system of this type is illustrated schematically in Figures 1 to 3 of the accompanying drawings. As shown in Figures 1 and 2, stackable containers, known as storage bins or containers 10, are stacked on top of one another to form stacks 12. The stacks 12 are arranged in a three dimensional grid framework structure 14 in a warehousing or manufacturing environment. The grid framework structure is made up of a plurality of storage columns or grid columns. Each grid in the grid framework structure has at least one grid column for storage of a stack of containers. Figure 1 is a schematic perspective view of the grid framework structure 14, and Figure 2 is a top-down view showing a stack 12 of bins 10 arranged within the framework structure 14. Each bin 10 typically holds a plurality of product items (not shown), and the product items within a bin 10 may be identical, or may be of different product types depending on the application. Bins 10 may also be referred to as storage bins or containers or storage containers or totes. In detail, the three dimensional grid framework structure 14 comprises a plurality of vertical uprights or upright members or upright columns 16 that support 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 comprising a plurality of grid cells 17. The grid cell has an opening to allow a load handling device to lift a container or storage bin through the grid cell. 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 point where the grid members intersect such that the upright members are interconnected at their tops ends by the intersecting grid members. The grid members 16, 18, 20 are typically manufactured from metal and typically welded or bolted together or a combination of both. The storage bins or containers 10 are stacked between the upright members 16 of the grid framework structure 14, so that the upright members 16 guard against horizontal movement of the stacks 12 of bins 10, and guide vertical movement of the storage bins 10. The top level of the grid framework structure 14 comprises a track system 15 comprising a plurality of tracks or rails 22 arranged in a grid pattern across the top of the stacks 12. Referring additionally to Figure 3, the tracks or rails 22 support a plurality of load handling devices 30. A first set 22a of parallel tracks or rails 22 guide movement of the robotic load handling devices 30 in a first direction (for example, an X-direction) across the top of the grid framework structure 14, and a second set 22b of parallel tracks or rails 22, arranged perpendicular to the first set 22a, guide movement of the load handling devices 30 in a second direction (for example, a Y-direction), perpendicular to the first direction. In this way, the plurality of tracks or rails 22 allow movement of the robotic load handling devices 30 laterally in two dimensions in the horizontal X-Y plane, so that a load handling device 30 can be moved into position above any of the stacks 12. A known load handling device or robotic load handling device otherwise known as a bot 30 shown in Figure 4 and 5 comprising a vehicle body 32 is described in PCT Patent Publication No. WO2015 / 019055 (Ocado), hereby incorporated by reference, where each load handling device 30 only covers a single grid space or grid cell of the grid framework structure 14. Here, the load handling device 30 comprises a wheel assembly comprising a first set of wheels 34 consisting of a pair of wheels on the front of the vehicle body 32 and a pair of wheels 34 on the back of the vehicle 32 for engaging with the first set of rails or tracks to guide movement of the device in a first direction, and a second set of wheels 36 consisting of a pair of wheels 36 on each side of the vehicle 32 for engaging with the second set of rails or tracks to guide movement of the device in a second direction. Each of the sets of wheels are driven to enable movement of the vehicle in X and Y directions respectively along the rails. One or both sets of wheels can be moved vertically to lift each set of wheels clear of the respective rails, thereby allowing the vehicle to move in the desired direction, e.g. X or Y direction on the grid structure. WO2017 / 153583 (Ocado Innovation Limited) teaches a load handling device comprising a wheel positioning mechanism or directional change mechanism for enabling lateral movement of the device in one of two transverse directions by enabling either a first or second set of wheels to selectively engage the first or second set of rails or tracks (22a or 22b). The wheel positioning mechanism comprises a complicated arrangement of linkages driven by a linear actuator or motor to selectively lower or raise the first set of wheels or the second set of wheels into engagement or disengagement with the first set of tracks or rails or the second set of tracks or rails. The load handling device 30 is equipped with a lifting mechanism or container lifting mechanism or crane mechanism to lift a storage container from above. The crane mechanism comprises a winch tether or cable 38 wound on a spool or reel (not shown) and a grabber device 39 in the form of a lifting frame. The lifting device comprise a set of lifting tethers 38 extending in a vertical direction and connected nearby or at the four corners of the lifting frame 39, otherwise known as the grabber device (one tether near each of the four corners of the grabber device) for releasable connection to a storage container 10. The grabber device 39 is configured to releasably grip the top of a storage container 10 to lift it from a stack of containers in a storage system of the type shown in Figure 1 and 2. The wheels 34, 36 are arranged around the periphery of a cavity or recess, known as a container-receiving recess 41, in the lower part. The recess is sized to accommodate the container 10 when it is lifted by the crane mechanism, as shown in Figure 5 (a and b). When in the recess, the container is lifted clear of the rails beneath, so that the vehicle can move laterally to a different location. On reaching the target location, for example another stack, an access point in the storage system or a conveyor belt, the bin or container can be lowered from the container receiving portion and released from the grabber device. The container receiving space may comprise a cavity or recess arranged within the vehicle body, e.g. as described in WO 2015 / 019055 (Ocado Innovation Limited). Alternatively, the vehicle body of the load handling device may comprise a cantilever as taught in WO2019 / 238702 (Autostore Technology AS), in which case the container receiving space is located below a cantilever of the load handing device. In this case, the grabber device is hoisted by a cantilever such that the grabber device is able to engage and lift a container from a stack into a container receiving space below the cantilever. Typically, the load handling device comprises one or more electrical components such as a rechargeable power source to provide power to the drive units for operating the lifting mechanism and the wheel positioning mechanism and a control unit. For example, one or more load handling devices remotely operable on the grid structure are configured to receive instructions from a master controller to a retrieve a storage container from a particular a storage location within the grid framework structure. Wireless communications and networks may be used to provide the communication infrastructure from the master controller via one or more base stations to the one or more load handling devices operative on the grid structure. A controller in the load handling device in response to receiving the instructions is configured to control various driving mechanisms to control the movement of the load handling device. For example, the load handling device may be instructed to retrieve a container from a storage column at a particular location on the grid structure. The instruction can include various movements in an X-Y direction on the grid structure. Once at the storage column, the lifting mechanism is then operated to grab the storage container and lift it into a container receiving space in the body of the load handling device where it is subsequently transported to a another location on the grid structure commonly known as a drop off port. The container is lowered to a suitable pick station allow retrieval of the item from the storage container. Movement of the load handling devices on the grid structure also involves the load handling devices being instructed to move to a charging station which is usually located at the periphery of the grid structure. The electrical components of the load handling device are typically housed within the body of the load handling device. Considering the number of components, which may include various motors, pulleys, and electrical components such as a power source and control board needed for the load handling device to operate on the grid framework structure, assembling of the individual components together is one of biggest costs in the manufacture of a load handling device. Considering that there may be hundreds of load handling devices operable on the grid framework structure, the cumulative costs of multiple load handling devices operable on the grid structure represent a significant proportion of the cost of a typical storage and retrieval system. Not only are the costs in the manufacture of the load handling devices representative of a significant proportion of the costs of the retrieval and retrieval system, but also the weight of the load handling device, which can weigh in excess of 150kg, can lead to other additional costs. For example, due to the weight of the load handling device, the grid framework structure needs to have sufficient structural integrity to bear the weight of multiple load handling devices operable on the grid framework structure. Various bracing elements can be used to increase the strength of the grid framework structure which ultimately adds to the costs of the grid framework structure, and thus the overall cost of the storage and retrieval system. As the weight of the load handling device increases, more power is also required to drive the wheel motors to move the load handing device on the tracks at a sufficient speed, which in turn translates into bigger and more powerful electrical motors and a bigger battery to provide the necessary power to drive the electrical motors. WO2023025418 (Ocado Innovation Ltd) teaches a load handling device for lifting and moving one or more containers stackable in a storage and retrieval system comprising a plurality of modular sections arranged in a vertical stack. The plurality of modular sections comprises a container lifting mechanism, a wheel assembly, a wheel positioning mechanism and electrical components, wherein each of the plurality of modular sections further comprises at least four connecting blocks, each of the at least four connecting blocks being connected to two other connecting blocks in a single modular section by one or more substantially horizontal connecting elements to form a rectangular frame. The at least four connecting blocks of vertically adjacent modular sections are connectable in the vertical stack by one or more substantially vertical connecting elements to form an open frame structure supporting the container lifting mechanism, the wheel assembly, the wheel positioning mechanism and the electrical component. One of the requirements of the load handling device is the ability of the load handling device to move on the track system of the grid framework structure without excessive wear of any of the wheels of the wheel assembly or the risk of derailing on the track system. The rails or tracks typically comprise an elongated element which is profiled to guide a load handling device on the grid structure and are typically profiled to provide either a single-track surface to allow a single load handling device to travel on the track, or a double track to allow two load handling devices to pass each other on the same track. In the case where the elongated element is profiled to provide a single track, the track comprises opposing lips (one lip on one side of the track and another lip at the other side of the track) along the length of the track to guide or constrain each wheel from lateral movement on the track. In the case where the profile of the elongated element is a double track, the track comprises two pairs of lips along the length of the track to allow the wheels of adjacent load handling devices to pass each other in both directions on the same track. To provide two pairs of lips, the track typically comprises a central ridge or lip and a lip either side of the central ridge. In all cases, when traversing on the grid structure, the wheels of the load handling device are constrained on both sides or faces of the wheels of the load handling device. Typically, there is a tight dimensional tolerance between the width of the wheel and the width of the track surface. This dimensional tolerance can be the order of a few millimetres. In the case the track is a double track, the spacing between adjacent load handling devices when passing each other on the track is a few millimetres. Any deviation from this, there is the risk that two load handling devices will clash when passing each other on the tracks. As the first and second sets of wheels are mounted to the frame structure of the load handling device, it is thus essential that the dimensional tolerance of the frame structure supporting the first and second set of wheels is precise to prevent the load handling device derailing on the tracks. For example, improper mounting of the first and second sets of wheels may result in the mounting of any one of the wheels being cambered. Not only does the dimensional tolerance of the frame structure have an impact on the wheel base and / or wheel track of the first and second sets of wheels, but also the dimensional tolerance of the frame structure may have an impact on the proper fitting of any of the other components of the load handling device, e.g., container lifting mechanism, a wheel positioning mechanism or the electrical components. To ensure the dimensional accuracy of the framework structure, the plurality of connecting blocks and connecting elements are assembled in a jig or fixture. The jig or fixture enables the connecting blocks to be connected to each other via the connecting elements to a predetermined precision. With the increasing demand for the manufacture of the frame structure on a large scale and to benefit from economies of scale, there has been a move towards removing the need to machine the connecting blocks in order to meet certain dimensional tolerances. Examples of such forming techniques that can form parts to a high level of dimensional accuracy is injection moulding or additive manufacturing, e.g., 3D printing. However, such forming techniques still suffer from dimensional intolerances, particularly when the being formed on a large scale as there is no guarantee that the dimensions of the block can be formed consistently. Whilst the use of jigs or fixtures helps to ensure that the frame structure is assembled to a required dimensional tolerance, there is a need to adjust the connections between the connecting blocks and the connecting elements should any one of the connections not properly meet the required dimensions in the jig or fixture. Thus, there is a need to be able to adjust a frame structure when assembling the connecting blocks and connecting elements in a jig or fixture. Summary of the Invention The present invention has mitigated the above problem by incorporating a moveable portion in the connecting block to compensate for any misalignment with adjacent or neighbouring connecting blocks in a jig or fixture. More specifically, the present invention provides a method of assembling a frame structure comprising a plurality of connecting blocks connectable together by a plurality of connecting elements, each of the plurality of connecting blocks comprising a connecting portion for connecting to a connecting element, said connecting portion of at least one of the plurality of connecting block is connected to a portion of said at least one of the plurality of connecting blocks by a moveable portion, the method comprising the steps of: i) connecting the connecting element to the connecting portion, the connecting element extending in a longitudinal direction along an axis; ii) moving the connecting element relative to the at least one of the plurality of connecting blocks by the moveable portion to change the angle of the connecting element with respect to the axis to define a setting angle; iii) setting the moveable portion to maintain the angle at the setting angle. When assembling the frame structure, adjacent or neighbouring connecting blocks are connected by one or more connecting elements. If there is a deviation when connecting to a neighbouring connecting block, the moveable portion connecting the connecting portion to the remaining portion of the connecting block enables the connecting element to be manipulated to change the angle of the connecting element for connecting to a neighbouring connecting block. Optionally, the connecting portion comprises a first connecting portion and a second connecting portion, the first and second connecting portions being connected together by the moveable portion and the plurality of connecting elements comprises a first connecting element and a second connecting element, the axis comprising a first axis and a second axis, the method comprising the steps of: i) connecting the first connecting element to the first connecting portion, the first connecting element extending in a longitudinal direction along the first axis; ii) connecting the second connecting element to the second connecting portion, the second connecting element extending in a longitudinal direction along the second axis, the second axis defining an angle with the first axis; iii) moving the first connecting portion relative to the second connecting portion by the moveable portion to change the angle to the setting angle; iv) setting the moveable portion to maintain the angle at the setting angle. Instead of just having one connecting portion connected to the connecting block by the moveable portion, optionally, the connecting portion can comprise a plurality of connecting portions. The connecting block comprises a first connecting portion for connecting to a first connecting element and a second connecting portion for connecting to a second connecting element. The first connecting portion can be configured so that the first connecting element extends longitudinally along the first axis and the second connecting portion can be configured so that the second connecting element extends longitudinally along the second axis, the second axis defining an angle with the first axis. In order to connect adjacent connecting blocks together, optionally, the connecting portion comprises a socket having a longitudinal axis extending in a direction parallel to the axis of the connecting element. Optionally, the socket comprises a first socket and a second socket such that the first connecting portion comprises the first socket having a longitudinal axis extending in a direction parallel to the first axis and the second connecting portion comprises the second socket having a longitudinal axis extending in a direction parallel to the second axis. The first and second sockets can be shaped to receive a connecting end of the connecting element in a “plug and socket” fit. Optionally, one or more of the connecting elements comprises a connecting rod or tube. Optionally, the connecting end of the connecting element is adhered to the connecting portion of the connecting block. Optionally, when assembling the frame structure, the plurality of connecting blocks comprises at least four connecting blocks, each of the four connecting blocks being connected to two other connecting blocks by one or more substantially horizontal connecting elements such that the frame structure comprises a substantially rectangular frame structure, i.e., the angle between the first and second axes is substantially 90°. Optionally, the frame structure can comprise a plurality of modular sections arranged in a vertical stack, each of the modular sections comprising the substantially rectangular frame structure, and wherein the at least four connecting blocks of vertically adjacent modular sections are connectable in the vertical stack by one or more substantially vertical connecting elements such that the frame structure comprises a plurality of the substantially rectangular frames. However, in order to assemble the frame structure to the correct dimensional tolerance and shape, it is essential that the connecting elements are properly aligned to the connecting portions of the connecting blocks. As the connecting blocks are manufactured on a large scale, there is the risk that one or more of the connecting blocks cannot be consistently manufactured to the same dimensional tolerance and shape. This could be as a result of the manufacturing process used to fabricate the connecting blocks or the even the type of material used to fabricate the connecting blocks, e.g., material shrinkage, or that the material is sensitive to the environmental conditions such as temperature and / or humidity during the manufacturing process. As a result, there is no guarantee of ensuring the consistency of the dimensional tolerance or shape of the connecting blocks when manufactured on a large scale. Should any one of the connecting elements become misaligned to a neighbouring connecting block in the assembly, and therefore fail to connect to the neighbouring connecting block, the moveable portion connecting the connecting portion to the connecting block allows the angle of the connecting element to be manually adjusted to connect to the neighbouring connecting block. As a result, the moveable portion compensates for any misalignment with an adjacent connecting block in the assembly. For the purpose of the definition of the present invention, manual adjustment includes but is not limited to bending the connecting portion relative to the connecting block by virtue of the moveable portion. There are various mechanisms by which the moveable portion can be introduced into the connecting block. Optionally, the moveable portion can comprise a deformable portion and / or a ball and socket joint and / or a linkage assembly. An example of a linkage assembly is a chain link. As the connecting portion is configured to move relative to the remainder portion of the connecting block via the moveable portion, optionally, the density of the connecting portion can be different to the density of the moveable portion. Once the plurality of connecting blocks are assembled to the correct dimensional tolerance and shape in the jig or fixture, the method further comprises the step of setting the moveable portion to maintain the angle at the setting angle. For the purpose of assembling a substantially rectangular frame structure, the setting angle is substantially 90°. Optionally, the method of setting the moveable portion comprises the step of applying an adhesive or resin to the moveable portion. Optionally, the moveable portion comprises a locking mechanism, and wherein the method of setting the moveable portion comprises the step of locking the moveable portion. To produce a lightweight load handling device, the connecting blocks can be formed from lightweight materials. Optionally, one or more of the plurality of connecting blocks can be formed from a plastic material. In comparison to metal, plastics offer the advantage of being light weight and durable. Optionally, the method further comprises the step of forming the at least one of the plurality of connecting blocks by additive manufacturing. Additive manufacturing provides the advantage of being able to form complex parts that cannot be produced by other forming techniques, e.g., injection moulding or casting. For example, the use of additive manufacturing in the fabrication of the connecting blocks allows one or more of the connecting blocks to be topology optimised to take into account the stresses that the connecting blocks would experience in the frame structure. The complex shapes formed by additive manufacturing allows the moveable portion to be integrated into the connecting block. For example, additive manufacturing allows the connecting block comprising the moveable portion can be integrally formed as a single body. In comparison to injection moulding where the dimensional shape and size is limited by the shape of the injection moulding tool, additive manufacturing also provides the flexibility to change the shape or dimensions of the connecting block to meet various design improvements. This is important when the frame structure is continuously being improved to increase the structural integrity of the frame structure, e.g. rigidity, strength etc. To assemble the frame structure to tight dimensional tolerances, the plurality of connecting blocks and connecting elements of the present invention can be assembled in jig or fixture. Optionally, the plurality of connecting blocks comprises a first connecting block and a second connecting block, the method comprising the steps of:- i) using a jig or fixture to position the first connecting block against a first predefined location in the jig, ii) positioning the second connecting block against a second predetermined location in the jig, iii) adjusting the connecting portion of the first and / or second connecting blocks to connect the first connecting block to the second connecting block by a connecting element. The present invention further provides a load handling device for lifting and moving one or more containers stackable in a storage and retrieval system, the storage and retrieval system comprising 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 such that 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) a container lifting mechanism comprising a grabber device configured to releasably grip a container, and a drive mechanism configured to raise and lower the grabber device, b) a wheel assembly comprising a first set of wheels for engaging with the first set of grid members to guide movement of the load handling device in a first direction and a second set of wheels for engaging with the second set of grid members to guide the movement of the load handling device in a second direction, wherein the second direction is transverse to the first direction; c) a wheel positioning mechanism configured for selectively lowering or raising the first set of wheels or the second set of wheels into engagement or disengagement with the first set of grid members or the second set of grid members; d) electrical components comprising a processor for controlling the container lifting mechanism and wheel positioning mechanism, wherein the container lifting mechanism, the wheel assembly, the wheel positioning mechanism and the electrical components is supported by a frame structure formed by the method according to the present invention. Optionally, one or more of the plurality of connecting blocks comprises 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, 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 is integrally formed with one or more of the plurality of connecting blocks. This removes the need to have a separate structural component that provides the structural integrity of the load handling device and separate functional components for the operation of the load handling device on the grid framework structure, since one or more of the connecting blocks can combine both the structural and functional aspects of the load handling device. Having one or more of the connecting blocks of the frame structure include both structural and functional components of the load handling device also reduces the weight of the load handling device since the number of parts in constructing the load handling device of the present invention is reduced. In the case where the moveable portion comprises a mechanical joint such as a ball and socket joint, the present invention further provides a load handling device for lifting and moving one or more containers stackable in a storage and retrieval system, the storage and retrieval system comprising 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 such that 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 frame structure comprising a plurality of connecting blocks, each of the plurality of connecting blocks comprising a connecting portion for connecting to a connecting element, the frame structure further comprising: a) a container lifting mechanism comprising a grabber device configured to releasably grip a container, and a drive mechanism configured to raise and lower the grabber device; b) a wheel assembly comprising a first set of wheels for engaging with the first set of grid members to guide movement of the load handling device in a first direction and a second set of wheels for engaging with the second set of grid members to guide the movement of the load handling device in a second direction, wherein the second direction is transverse to the first direction; c) a wheel positioning mechanism configured for selectively lowering or raising the first set of wheels or the second set of wheels into engagement or disengagement with the first set of grid members or the second set of grid members; d) electrical components comprising a processor for controlling the container lifting mechanism and wheel positioning mechanism, wherein the connecting portion of at least one of the plurality of connecting blocks comprises a mechanical joint. The container lifting mechanism, the wheel assembly, the wheel positioning mechanism and the electrical components can be supported to or mounted to the frame structure. Optionally, the mechanical joint comprises a ball and socket joint. Optionally, said at least one of the plurality of connecting blocks comprises an opening in fluid communication with the socket for injecting a fluid into the socket, e.g. adhesive or resin. To incorporate a ball and socket joint, the ball is configured to connect to the connecting element, i.e., the ball comprises the connecting portion for connecting to a connecting element. The present invention further provides an automated storage and retrieval system, the system 5 comprising: 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 such that the plurality of grid members are arranged in a grid pattern for guiding the movement of one or more the load handling devices 10 operating on the grid structure; and at least one load handling device according to the present invention. Brief Description of Drawings Further features and aspects of the present invention will be apparent from the following detailed description of an illustrative embodiment made with reference to the drawings, in which: Figure lisa schematic diagram of a grid framework structure according to a known system, Figure 2 is a schematic diagram of a top down view showing a stack of bins arranged within the framework structure of Figure 1. Figure 3 is a schematic diagram of a known storage system of a load handling device operating on the grid framework structure. Figure 4 is a schematic perspective view of the load handling device showing the lifting device gripping a container from above. Figure 5(a) and 5(b) are schematic perspective cut away views of the load handling device of Figure 4 showing (a) a container accommodated within the container receiving space of the load handling device and (b) the container receiving space of the load handling device. Figure 6 is a schematic drawing of the load handling device according to an embodiment of the present invention. Figure 7(a and b) are schematic drawings of (a) the different modular sections of the load handling device shown in Figure 6; and (b) an analogy of the different modular sections as separate rectangular frames formed by four connecting blocks. Figure 8 (a and b) are schematic drawings of (a) an assembly of the modular sections shown in Figure 7(a) to form a frame structure of the load handling device; and (b) a simplified version of an assembly of the rectangular frames of the modular sections shown in Figure 7(b) to form an open frame structure of the load handling device. Figure 9 (a and b) is a schematic drawing of (a) a connecting block comprising a moveable portion connecting first and second connecting portions of the connecting block; and (b) showing the movement of at least one of the connecting portions relative to the other connecting portion by the moveable portion. Figure 10(a and b) is a schematic drawing of (a) a connecting block comprising a moveable portion formed as a mechanical joint according to a second example of the present invention; and (b) showing the interaction of the connecting element with the moveable portion of the connecting block. Figure 11 is an illustration of the mechanical joint comprising a ball and socket joint; the ball having a knurled surface to key in the adhesive. Figure 12 is an illustration of setting the mechanical joint shown in Figures 10(a and b) and Figure 11 to a setting angle by injection of adhesive into the socket. Figure 13(a and b) is a schematic drawing of (a) a connecting block comprising a moveable portion according to a third example of the present invention; and (b) showing the interaction of the connecting element with the moveable portion of the connecting block. Figure 13(c and d) is a schematic drawing of (c) the connecting end of the connecting element shown in Figure 13a being inserted into the socket of the connecting block; and (d) the connecting element being manipulated when inserted into the socket. Figure 14 is a schematic drawing showing a frame structure formed by assembling connecting blocks shown in Figures 9(a and b). Figure 15 is a schematic drawing showing a frame structure formed by assembling connecting blocks shown in Figures 10(a and b). Figure 16 is an illustration of setting the connecting portion to a setting angle by a grub screw. Figure 17 is a schematic drawing of an example of a topology optimised connecting block for assembling at least one of the modular sections of the frame structure of the load handling device. Figure 18 is a schematic drawing of an example of a topology optimised connecting block forming the wheel mounts of the frame structure. Figure 19 is a schematic drawing of a top view of an assembly of connecting blocks and connecting elements in a jig to provide a portion of the frame structure of the load handling device. Figure 20 is a schematic drawing of an isometric view of the assembly of connecting blocks and connecting elements in a jig to provide a portion of the frame structure of the load handling device. Detailed Description It is against the known features of the storage system such as the grid framework structure and the load handling device described above with reference to Figures 1 to 5, that the present invention has been devised. Frames or similar structures are used in various applications and are distinguished from shell type structures or solid structures by the purpose of their design. Whereas shell structures use exterior strength to retain their shape when bearing a load on the inside, frame structures are designed to bear both external and / or internal loads. The advantage of frame structures over solid structures is that they can be constructed from lightweight materials. Where the frame forms part of a build comprising various functional components for the operation of the build, it is necessary that the frames are load bearing for supporting the various functional components of the build. Not only should the frame be load bearing, but also the frame should be sufficiently rigid to ensure that the dimensional tolerances of the frame do not change under an applied external force. Examples of builds that require the use of the frames that are both load bearing and rigid include but are not limited to a bicycle frame, and various other vehicle frames etc. Typically, the frame or structure is constructed from separate load bearing elements that are assembled together. Various fasteners and / or adhesives and / or resins can be used to join the separate load bearing elements together. The physical characteristics of the load bearing elements such as flexural rigidity depends largely on the application of the build. An example of the construction of a build comprising the frame structure is the construction of a robotic load handling device for lifting and moving one or more containers stackable in a storage and retrieval system. Connecting blocks 46 are used to join the load bearing connecting elements 48 together in the construction of the frame structure 44. The connecting elements 48 can be any straight connecting element including but are limited to a rod, tube or pipe and can comprise a plastic material, metal material and / or ceramic material and / or a composite material. Example of a composite material that possess the necessary physical characteristics of lightweight, high stiffness, high tensile strength and high strength to weight ratio is carbon fibre in a polymer matrix. Various techniques can be used to secure the connecting blocks to the connecting elements. These include the use of an adhesive or glue, fasteners or welding or a combination of any one of these securing methods. The use of an adhesive to secure the connecting block 46 to the connecting element 48 appears to be the most efficient and cost effective way to assemble the frame structure 44 together. To connect the connecting elements 48 to neighbouring connecting blocks 46 in the frame structure 44, each of the connecting blocks 46 comprises a connecting portion 50. The connecting portion 50 can be a socket or an opening as shown in Figures 9(a and b) or a spigot (not shown) for connecting to the connecting element. A load handling device 130 comprising a frame structure 44 constructed from a plurality of connecting blocks 46 linked together by connecting elements 48 is shown in Figure in 6 and taught in WO2023025418 (Ocado Innovation Ltd), the details of which are incorporated herein by reference. The construction of the load handling device 130 is based around the principle of having a modular system comprising a plurality of modules or modular sections that are connectable in a vertical stack to provide the different functional characteristics of the load handling device. In a further aspect of the present invention, the modular system is integrated into a frame structure or skeleton 44 such that the frame structure comprises a plurality of modular frames or sub frames that are connectable to one another in a vertical stack to provide the different functional characteristics of the load handling device (see Figures 8(a and b). The term “frame structure” and “skeleton” are used interchangeably in the 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 frame structure of the load handling device. An example of a load handling device 130 incorporating the inventive concepts of the present invention is shown in Figure 6. A simplified breakdown of the different modular sections providing the different functional characteristics of the load handling device are shown in Figure 7(a and b). The different modular sections 132(a and b), 134(a and b), 136(a and b), 138(a and b) are labelled, 1st, 2nd, 3rd and 4th modular sections respectively in Figure 7 (a and b). As can be appreciated from the exploded view of the load handling device shown in Figure 7 (a and b), the different modular sections of the load handling device comprise connecting blocks 46 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 vertically stacked. Each modular section can be envisaged as a rectangular frame structure or sub-frame structure formed by connecting or linking together connecting blocks as shown in Figures 8(a and b). A modular section is built by connecting adjacent connecting blocks in the same horizontal plane by one or more connecting elements 44 to form the sub-frame structure 52. Vertically adjacent sub-frames structures 52 are thus connected together by connecting vertically adjacent connecting blocks 46 as shown in Figure 9(a and b) to form the frame structure 44. An example of a connecting block 44 is a corner bracket. In a singular modular section, each connecting block is connected to two other connecting blocks in the same horizontal plane by one or more connecting elements 48. The connecting elements 46 can be connecting rods or tubes for linking adjacent connecting blocks (corner brackets) together in a single modular section. The connecting rods can be solid or hollow and is dependent on the connection with the connecting block. In the particular embodiment of the present invention, the frame structure is a three dimensional structural defining a volume having an upper portion for housing the power source 180, the control unit 192, the spools 182 carrying the lifting tethers, and a lower portion housing the container receiving space 137. In the particular embodiment of the present invention shown in Figure 7 (a and 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 tier based modular system. Starting from the bottom modular section 132(a and b) and increasing in height of the load handling device, the four modular sections for the purpose of explanation of the present invention are labelled first 132(a and b), second 134(a and b), third 136(a and b) and fourth 138(a and b) modular sections. The four modular sections provide the different functional characteristics of the load handling device. In the particular embodiment of the present invention, the different functional characteristics of the load handling device can be shared amongst 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 can be shared amongst 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 characteristics of the load handling device can be divided amongst any number of modular sections. The different functional characteristics of the load handling device include but are not limited to the wheel assembly for allowing movement of the load handling device on the grid structure or tracks, the wheel drive assembly to drive the wheel assembly to enable the load handling device to move on the grid structure, the wheel positioning mechanism, otherwise known as the directional change mechanism, the container lifting mechanism for picking up and dropping off a container to and from a grid cell of the grid framework structure, and the electrical or electronic components of the load handling device. As discussed above in the introductory part of the patent specification, the electrical components can optionally comprise a control unit for controlling the operation of the wheel drive assembly, the wheel positioning mechanism and the drive mechanism of the container lifting mechanism. Typically, the wheel drive assembly, the wheel positioning mechanism and the drive mechanism of the container lifting mechanism comprise one or more electrical motors. Other components of the electrical components of the load handling device include but are not limited to the power source for providing power to drive the wheel drive assembly and the drive mechanism of the container lifting mechanism. Typically, the power source is a rechargeable power source or battery. Examples of rechargeable batteries are Lithium-Ion battery, Nickel-Cadmium battery, Nickel-Metal Hydride battery, Lithium-Ion Polymer battery, Thin Film battery and Smart battery Carbon Foam-based Lead Acid battery. An example of the connecting blocks comprising one or more functional characteristics of the load handling device is shown in Figures 17 and 18. Figure 17 is an example of a connecting block 146 for connecting to two other connecting blocks in the frame structure to form a modular section or a sub-frame structure 52 and Figure 18 is an example of the connecting block 246 incorporating the wheel mounts 54a,b of the wheel assembly. In the example shown in Figure 18, the connecting block 246 is formed in two parts for accommodating two wheel mounts 54a,b, namely a first and second wheel mount 54a, b. The first wheel mount 54a is configured for mounting a wheel of the first set of wheels 34 and the second wheel mount 54b is configured for mounting a wheel of the second set of wheels 36 (such that there is a total of eight wheels mounted to four connecting blocks 246; two wheel mounts for each of the four connecting blocks 140e and arranged to support the open frame structure of the load handling device). The structural integrity of the frame structure should be sufficient to not only support the different functional characteristics of the load handling device but also have sufficient flexural rigidity when the load handling device is operational 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 metal or polymers (e.g., plastic materials) or ceramic or a combination thereof. To reduce the weight of the load handling device and have the necessary structural properties to support the different functional components of the load handling device, optionally the connecting rods linking adjacent connecting blocks together are composed of carbon fibre bound in a polymer matrix (known as carbon fibre rods). To aid with the construction of the rectangular frame structures forming the modular sections, each of the connecting blocks of one or more of the modular sections or sub frame structures comprises a connecting portion for connecting to one or more connecting elements. In the example illustrated in Figures 9(a and b), the connecting portion comprises an opening or socket 50 for insertion of the connecting rods. The connecting rod is fixed to the connecting block 46 by a joint. Various techniques can be used to secure the connecting blocks 46 to the connecting elements. These include the use of an adhesive or glue, fasteners or welding or a combination of any one of the securing methods. The use of an adhesive to secure the connecting block to the connecting element appears to be the most efficient and cost effective way to assemble the open framework structure comprising connecting blocks linked together by a plurality of connecting elements. A glue channel comprising a groove (not shown) can be incorporated into the opening or socket for distributing glue or adhesive around the connecting end of the rod or tube of the connecting element. The connecting block 46 can comprise an inlet (not shown) having an inlet opening external of the connecting block and in fluid communication with the groove for injecting adhesive into the groove, the groove being configured to form a glue channel when the connecting end of the rod is inserted into the socket such that when adhesive is injected into the inlet opening, the adhesive flows along the glue channel around the outer surface of the connecting end of the rod. Different shapes of grooves can be formed within the internal wall of the socket. Further details of the glue channel are taught in WO2023144226 (Ocado Innovation Limited), the contents of which are incorporated herein by reference. As the load handling device is destined to travel on a grid framework structure discussed in the introductory section of the description comprising a track system comprising a plurality of tracks arranged in a grid pattern, and to ensure that the frame structure of the load handling device meets the required dimensional tolerance and shape to move on the tracks, a jig or fixture is used to ensure that the connecting elements are correctly aligned and / or orientated in the frame structure. The jig or fixture controls the location of the connecting blocks and connecting elements to provide repeatability, accuracy and interchangeability in the manufacturing of the frame structure or sub-frame structure. An example of a jig or fixture 56 used for the assembly of a sub-frame structure 52 in the building of a robotic load handling device is shown in Figures 19 and 20. Typically, the jig or fixture 56 comprises one or more mounting blocks 60 and / or clamps 58 comprising one or more datum points or guides that control the orientation of the connecting elements relative to the connecting blocks of the present invention, i.e. it is a work holding device that holds, supports and locates the connecting blocks and / or connecting elements during assembly to predefined locations. Using a jig or fixture 56 shown in Figures 19 and 20 to correctly locate the connecting elements 48 within the connecting blocks 46 may involve movement or adjustment of the angle of the connecting elements relative to the connecting blocks. To allow the orientation of the connecting element to be changed when inserted into the connecting block, the cross-sectional dimension of the socket 50 is made purposively larger than the outer cross-sectional dimension of the connecting element, i.e., in the case of a rod or tube, the diameter of the rod or tube. Movement of the connecting element within the socket allows different orientations of the connecting element relative to the connecting block depending on the datum points in the fixture or jig. As discussed above, various forming techniques can be used in the formation of the connecting blocks. These includes various moulding techniques including but are not limited to additive manufacturing (3D printing), injection moulding, casting etc. However, the reproducibility of the moulded parts is dependent on several factors or conditions that usually cannot be accurately controlled or monitored. These include but are not limited to the environmental conditions, e.g., temperature, the consistency of the raw materials, etc. Whilst stringent quality control measures are used to ensure the reproducibility of the moulded parts, there are still some discrepancies in the reproducibility of like parts which will eventually manifest in a discrepancy in one or more dimensions or geometry of the frame structure comprising the moulded parts. Whilst such discrepancies in the dimensions or geometry of the frame structures can be absorbed to some extent by making adjustments to the connecting elements within the sockets of the connecting blocks, such adjustments may not go far enough. Such a discrepancy in the dimension and / or geometry of the frame structure can have an impact on the functional characteristics of a build. For example, where the frame structure or subframe structure forms part of a build comprising wheels for manoeuvring the build on a surface, e.g. a vehicle, any discrepancy in the dimension and / or geometry of the sub-frame structures may have a detrimental impact on the alignment of the wheels mounted to the frame structure. In a worst case scenario, misalignment of the wheels having a pair of wheels at the front and rear of the vehicle as a result of a discrepancy in dimension of one of the sub-frame structures may cause the movement of the vehicle to yaw or be driven in an off-lead angle. This discrepancy in the dimension and / or geometry of the assembled frame structure may be largely attributable to the differences in the dimensional tolerance of the connecting block and / or the connecting element. In addition to or alternatively to adjusting the connecting elements within the sockets of the connecting blocks, in a further aspect of the present invention, the connecting portion is connected to the connecting block by a moveable portion to allow the connecting portion to move relative to the connecting block. There are various means for the moveable portion to connect the connecting portion to the connecting block. In the example shown in Figures 9(a and b), the connecting block 46 comprises a first connecting portion 62 and a second connecting portion 64, the first and second connecting portions 62, 64 being connected by moveable portions 66, 68 to allow the first connecting portion 62 to move relative to the second connecting portion 64. The moveable portions 62, 64 connecting the different connecting portions 62, 64 of the connecting block provides the flexibility to adjust the angle of the connecting elements connected to their respective connecting portions of the connecting block. In the illustrated example shown in Figures 9(a and b), the moveable portions 66, 68 are shown sandwiched between the central portion of the connecting block and their respective connecting portions. In the illustration of the connecting block shown in Figure 9(a and b), the first and second connecting portions 62, 66 can comprise one or more sockets 50 discussed above for receiving the connecting ends of the connecting elements, e.g. tubes. However, other means for connecting the connecting elements to the connecting portions of the connecting block are permissible in the present invention. These include but are not limited to the use of spigots shaped to be received in the tubes of the connecting element, the use of a bracket etc. The moveable portion 66, 68 can be any structurally compliant material or compliant mechanisms that enable different connecting portions of the connecting block to move relative to each other to change the shape of the connecting block in the jig or fixture. In the example illustrated in Figures 9(a and b), the moveable portions 66, 68 of the connecting block comprise a deformable portion that is integrated into the body of the connecting block. Integration of the compliant portion into the body of the connecting block can be achieved when forming the connecting block from a single or monolithic material, e.g., monolithic polymer, by additive manufacturing discussed above. Examples of a compliant portion connecting different portions of the connecting block, which is deformable and which can be integrated into the body of the connecting block, include but are not limited to a cellular structure (e.g., a closed cell or open cell cellular structure). As a result, the density of the connecting portions 62, 64 is different to the density of the deformable portion 66, 68 to enable the deformable portion to deform differently to the connecting portions. Once the different connecting portions of the connecting block have been manipulated via the moveable portion for connecting to an adjacent connecting block in the frame structure by one or more connecting elements, the moveable portion can be set in place. For the purpose of definition, the phrase “setting in place” is construed to mean fixing the shape of the connecting block such that connecting elements connected to the connecting block are set at a setting angle relative to the connecting block. There are various examples to setting the moveable portion once one or more connecting portions are manipulated into shape. These include but are not limited to applying an adhesive to the moveable portion and setting the moveable portion in its deformed state by curing the adhesive or use of a locking mechanism to lock the moveable in its deformed state. Further detail of setting the flexible portion when the connecting block is deformed via the moveable portion is discussed below. To allow different regions of the connecting block to be manipulated in more than one area of the connecting block, the at least one moveable portion 66, 68 can comprise a plurality of moveable portions. In the illustrated example shown in Figure 9a, the connecting block comprises a first moveable portion 66 and a second moveable portion 68. The first moveable portion 66 connects two portions of the connecting block and the second moveable portion 68 connects two different or separate portions of the connecting block. The first moveable portion 66 connects the first connecting portion 62 of the connecting block and the second moveable portion 68 connects the second connecting portion 64 of the connecting block. By virtue of the compliant material, the shape of the connecting block, and thus the angle between the connecting portions, can be changed in more than one way by deforming the first or second moveable portions of the connecting block. The first connecting portion 62 is configured to connect to a connecting element extending in a longitudinal direction along a first axis, Z-Z, and the second connecting portion 64 is configured to connect to a connecting element extending in a longitudinal direction along a second axis, X-X. As a result, the one or more sockets 50 of the first connecting portion 62 has a longitudinal axis parallel to the first axis, Z-Z, and the one or more sockets 50 of the second connecting portion 64 has a longitudinal axis parallel to the second axis, X-X. Since the connecting elements connected to the first and second connecting portions extend along the first and second axes respectively, the connecting elements intersect at the angle a. In its natural or undeformed state of the connecting block, the angle a is substantially 90° (see Figure 9a). However, where there is a discrepancy in the dimension or shape of the frame structure when a plurality of connecting blocks and connecting elements are assembled in a jig or fixture, the body of one or more connecting blocks in the assembly can be deformed by moving the first 62 or second connecting portions 64 relative to the other of the second or first connecting portions respectively to vary the angle a (see Figure 9b). Such an angle once varied by deforming the compliant material can be defined as the setting angle, since the change in angle is as a result of moving one of the connecting portions. The deformable portion of the connecting block allows the shape of the connecting block to be changed to compensate for any discrepancies in the shape of one or more connecting blocks and / or to enable the connecting block to be connected to an adjacent connecting block in the jig or fixture. An example of a frame structure 144 formed from an assembly of connecting blocks 46 connected by a plurality of connecting elements 48 is shown in Figure 14. The entire frame structure 144 can be assembled in a single jig or fixture or assembled from an assembly of sub-frame structures or modular sections, each of the sub-frame structures being assembled in a separate jig or fixture and then subsequently assembled to form the frame structure shown in Figure 14. In both cases, to meet the tight dimensional tolerances for the frame structure to be assembled in the jig or fixture, the shape and / or geometry of the frame structure can be changed by manipulating at least one of the connecting portions of a connecting block. The moveable portion is not limited to a compliant or deformable material discussed above and can be a moveable joint 70, 72 to enable manipulation of the connecting element 48 connected to the connecting block 46 as shown in Figures 10(a and b) and Figures 13(a and b). In comparison to the compliant material where manipulation occurs by changing the shape of the connecting block, manipulation of the moveable joint 70, 72 occurs by moving the connecting element 48 relative to the connecting block 46. Like the compliant material, the moveable joint 70, 72 can be integrated into the body of the connecting block. For example, the connecting block comprising the moveable joint can be formed from a single or monolithic material as the rest of the connecting block, e.g., by additive manufacturing. In the illustrated example shown in Figure 10(a and b), the movable joint 70 comprises a ball 74 and socket 76 joint, wherein the ball and socket are formed within the body of the connecting block. In comparison to the compliant portion, wherein the body of the connecting block can be manipulated to change the shape of the connecting block, the socket 70 of the moveable joint is oversized to enable the ball 74 to be rotated within the socket 76. The advantage of the moveable joint over the compliant material is that the moveable joint can be configured to accommodate the adhesive for setting the moveable joint in place to the setting angle. The setting angle, a, in this case, is the angle the connecting element deviates from its default axis, e.g. X-axis, as a result of moving the connecting element (see Figure 10). In the case of the ball and socket joint, the spacing between the inner wall of the socket 76 and the exterior surface of the ball 74 (herein defined as a glue channel) provides a space for accommodating adhesive therebetween. The connecting block 46 comprises an inlet 78 having an inlet opening external of the connecting block 46 and in fluid communication with the socket 76 for injecting adhesive into the glue channel (see Figure 12). Any suitable injection tool or syringe or gun 80 with a suitable nozzle can be used to inject adhesive into the socket 76. The ball comprises a connecting portion for connecting to a connecting element. In the illustrated example shown in Figure 10(a and b), the connecting portion of the ball 74 comprises an opening or socket 50 for receiving the connecting end of the connecting element 48. Equally plausible is the ball comprises a spigot for being received in an opening in the connecting element. In comparison to the example of the connecting block shown in Figures 9(a and b), the connecting portion is formed into the moveable joint; in this case, the ball of the moveable joint. In either case, when connected to the ball, the connecting element can be manipulated by rotating the ball to change the angle of the connecting element with respect to the connecting block to the setting angle, a. When a plurality of connecting blocks are assembled together by a plurality of connecting elements to form a frame structure 244 as illustrated in Figure 15, any deviation in the connecting elements 48 to connect to an adjacent connecting block 46 in the frame structure 244 can be overcome by manipulating one or more connecting elements to change their respective angles. In this way, any discrepancies in one or more connecting blocks in order to meet tight dimensional tolerances in the jig or fixture can be compensated by manipulating one or more of the connecting elements to change their respective angles by virtue of the moveable joint connected to the connecting element. To aid with setting the ball 74 in the socket 76, the ball 74 can optionally comprise a knurled surface 82 for keying with the adhesive as illustrated in Figure 11. The knurled surface 82 illustrated in Figure 11 comprises a plurality of grooves for keying with the adhesive and prevents the ball from rotating in the socket once the adhesive has cured. Alternatively, the connecting end of the connecting element 48 and the socket 50 of the connecting portion cooperate to provide one or more stops to prevent separation of the connecting element from the socket once the socket is filled with adhesive. Alternatively or additionally, to secure the connecting element in the socket, the connecting end of the connecting element 48 comprises a spline 84 that keys with the adhesive when inserted into the socket 50. In the particular example of the present invention shown in Figures 13(a and b), the spline 84 comprises a step 86, but other types of splines for keying with the adhesive in the socket are applicable in the present invention. Once the adhesive has cured, the step 86 at the connecting end of the connecting element prevents the connecting element from being withdrawn from the socket 50. As illustrated in Figures 13(a and b), the moveable portion comprises an oversized portion 88 and a narrow portion 89. The socket 50 is in communication with or extends into the narrow portion 89 for guiding the connecting end of the connecting element into the oversize portion 88. The oversize portion 88 allow the connecting end of the connecting element to be manually manipulated in the socket and thereby to change its angle to connect to an adjacent connecting block in a jig or fixture. The step between the oversize portion and the narrow portion of the socket 50 helps to secure the connecting end of the connecting element in the socket 50. To prevent the adhesive or resin from escaping the connecting block 46 via the socket 50 once injected into the oversized portion 88 of the moveable portion, the socket 50 can optionally, comprise a grommet or seal 94 at the mouth of the socket 50 as shown in Figure (c). The grommet 94 forms a seal between the mouth of the socket 50 and the connecting element 48 when the connecting element 48 is injected into the socket as shown in Figure 13(d). The grommet 94 can be formed from any compliant material, e.g., rubber, fibrous material, to allow the connecting element 48 to be moved to adjust the angle of the connecting element relative to the connecting block 46. Once adjusted, the oversize portion of the moveable portion is injected with adhesive via the inlet 78 to set the connecting element at the setting angle, a. In addition to or alternatively to setting the moveable joint in the connecting block by an adhesive, the moveable joint can be set at the setting angle in the connecting block by a locking mechanism 90. The locking mechanism 90 can comprise a grub screw 92 that is configured to lock the moveable joint from movement. In the particular example illustrated in Figure 16, the grub screw 92 is shown engaging with the ball 74 of the moveable joint, thereby preventing the ball from rotating in its socket 76. In operation when assembling a plurality of connecting blocks and connecting elements in a jig or fixture as exemplified in Figures 19 and 20, the assembler would connect a first connecting block to a second connecting block by connecting their respective connecting portions via connecting elements. In the example shown in Figure 19 and 20, tubes are used to connect the first and second connecting blocks by being received in their respective sockets. To ensure that the construction of the frame structure meets tight dimensional tolerances, one or more datums can be used to correctly position the connecting blocks in the jig or fixture. Should any of their connecting portions fail to connect to an adjacent connecting block in the jig or fixture, the angle of connecting elements can be adjusted. Where the moveable joint comprises a compliant portion, the shape of the connecting block can be changed by deforming the compliant portion connected to the connecting portion. Equally, where the moveable joint comprises a mechanical joint such as a ball and socket joint, adjustment to the angle of the connecting element involves rotating the ball connected to the connecting element within its socket in the connecting block. Once the angle of the connecting element is adjusted to connect a neighbouring connecting block, the moveable portion of the connecting block is set at the setting angle. This could be using an adhesive or alternatively a mechanical locking mechanism as discussed above. Although the present invention has been described hereinabove by way of the illustrative examples thereof, it can be modified, without departing from the spirit, scope and nature of the present invention as defined in the claims.

Claims

1. A method of assembling a frame structure comprising a plurality of connecting blocks connectable together by a plurality of connecting elements, each of the plurality of connecting blocks comprising a connecting portion for connecting to a connecting element, said connecting portion of the at least one of the plurality of connecting blocks is connected to said at least one of the plurality of connecting blocks by a moveable portion, the method comprising the steps of:i) connecting the connecting element to the connecting portion, the connecting element extends in a longitudinal direction along an axis;ii) moving the connecting element relative to the at least one of the plurality of connecting blocks by the moveable portion to change the angle of the connecting element with respect to the axis to define a setting angle with respect to the axis;iii) setting the moveable portion to maintain the angle at the setting angle.

2. The method of claim 1, wherein the connecting portion comprises a first connecting portion and a second connecting portion, the first and second connecting portions being connected together by the flexible portion, the plurality of connecting elements comprising a first connecting element and a second connecting element, the axis comprising a first axis and a second axis, the method comprising the steps of:i) connecting the first connecting element to the first connecting portion, the first connecting element extending in a longitudinal direction along the first axis;ii) connecting the second connecting element to the second connecting portion, the second connecting element extending in a longitudinal direction along the second axis, the second axis defining an angle with the first axis;iii) moving the first connecting portion relative to the second connecting portion by the moveable portion to change the angle to the setting angle;iv) setting the moveable portion to maintain the angle at the setting angle.

3. The method of claim 1 or 2, wherein the moveable portion comprises a deformable portion and / or a moveable joint.

4. The method of claim 3, wherein the moveable joint comprises a ball and socket joint and / or a linkage assembly.

5. The method of any of the preceding claims, wherein the density of the connecting portion is different to the density of the moveable portion.

6. The method of any of the preceding claims, wherein the method of setting the moveable portion comprises the step of applying an adhesive to the moveable portion.

7. The method of any of the preceding claims, wherein the moveable portion comprises a locking mechanism, and wherein the method of setting the moveable portion comprises the step of locking the moveable portion.

8. The method of any of the preceding claims, where the moveable portion comprises a plurality of moveable portions, each of the plurality of moveable portions connecting a different portion of the at least one connecting block.

9. The method of any of the preceding claims, wherein the connecting portion comprises a socket having a longitudinal axis extending in a direction parallel to the axis.

10. The method of claim 2 and 9, wherein the socket comprises a first socket and a second socket, the first connecting portion comprises the first socket having a longitudinal axis extending in a direction parallel to the first axis and the second connecting portion comprises the second socket having a longitudinal axis extending in a direction parallel to the second axis.

11. The method of any of the preceding claims, wherein the angle or the setting angle is substantially 90°.

12. The load handling device of any of the preceding claims, wherein one or more of the connecting elements comprises a connecting rod or tube.

13. The method of any of the preceding claims, wherein the at least one of the plurality of connecting blocks is monolithic.

14. The load handling device of any of the preceding claims, wherein one or more of the plurality of connecting blocks is formed from a plastic material.

15. The method of any of the preceding claims, further comprising the step of forming the at least one of the plurality of connecting blocks by additive manufacturing.

16. The method of any of the preceding claims, wherein the plurality of connecting blocks comprises at least four connecting blocks, each of the four connecting blocks being connected to two other connecting blocks by one or more substantially horizontal connecting elements such that the frame structure comprises form a substantially rectangular frame structure.

17. The method of claim 16, wherein the frame structure comprises a plurality of modular sections arranged in a vertical stack, each of the modular sections comprising the substantially rectangular frame structure, and wherein the at least four connecting blocks of vertically adjacent modular sections are connectable in the vertical stack by one or more substantially vertical connecting elements such that the frame structure comprises a plurality of the substantially rectangular frame structures.

18. The method of any of the preceding claims, wherein the plurality of connecting blocks comprises a first connecting block and a second connecting block, the method comprising the steps of:-i) using a jig or fixture to position the first connecting block against a first predefined location in the jig,ii) positioning the second connecting block against a second predefined location in the jig,iii) adjusting the connecting portion of the first and / or second connecting blocks to connect the first connecting block to the second connecting block by the connecting element.

19. A load handling device for lifting and moving one or more containers stackable in a storage and retrieval system, the storage and retrieval system comprising 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 such that 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 connecting blocks connectable together by a plurality of connecting elements, the frame structure comprising:a) a container lifting mechanism comprising a grabber device configured to releasably grip a container, and a drive mechanism configured to raise and lower the grabber device;b) a wheel assembly comprising a first set of wheels for engaging with the first set of grid members to guide movement of the load handling device in a first direction and a second set of wheels for engaging with the second set of grid members to guide the movement of the load handling device in a second direction, wherein the second direction is transverse to the first direction;c) a wheel positioning mechanism configured for selectively lowering or raising the first set of wheels or the second set of wheels into engagement or disengagement with the first set of grid members or the second set of grid members;d) electrical components comprising a processor for controlling the container lifting mechanism and wheel positioning mechanism,wherein the frame structure formed by the method as defined in any of the claims 1 to 18.

20. The load handling device of claim 19, wherein one or more of the plurality of connecting blocks comprises 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.

21. The load handling device of claim 20, 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 is integrally formed with one or more of the plurality of connecting blocks.

22. A load handling device for lifting and moving one or more containers stackable in a storage and retrieval system, the storage and retrieval system comprising 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 such that 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 frame structure comprising a plurality of connecting blocks, each of the plurality of connecting blocks comprising a connecting portion for connecting to a connecting element, the frame structure comprising:a) a container lifting mechanism comprising a grabber device configured to releasably grip a container, and a drive mechanism configured to raise and lower the grabber device;b) a wheel assembly comprising a first set of wheels for engaging with the first set of grid members to guide movement of the load handling device in a first direction and a second set of wheels for engaging with the second set of grid members to guide the movement of the load handling device in a second direction, wherein the second direction is transverse to the first direction;c) a wheel positioning mechanism configured for selectively lowering or raising the first set of wheels or the second set of wheels into engagement or disengagement with the first set of grid members or the second set of grid members;d) electrical components comprising a processor for controlling the container lifting mechanism and wheel positioning mechanism,wherein the connecting portion of at least one of the plurality of connecting blocks comprises a mechanical joint.

23. The load handling device of claim 22, wherein the mechanical joint comprises a ball and socket joint.

24. The load handling device of claim 23, wherein the at least one of the plurality of connecting blocks comprises an opening in fluid communication with the socket for injecting a fluid into the socket.

25. An automated storage and retrieval system, the system comprising: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 such that the plurality of grid members are arranged in a grid pattern for guiding the movement of one or more the load handling devices operating on the grid structure; andat least one load handling device according to any of the claims 19 to 24.36

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