Automated Storage Systems and Equipment

Abstract

To provide a modular load handling device that is lightweight and easy and / or inexpensive to maintain.SOLUTION: A drive belt assembly for a load handling device comprises: a drive belt 271; a drive wheel 275; one or more driven wheels 116; and tensioning means which has a fixed end above an elbow part and a rotatable distal end pivotally mounted at the elbow part, and comprises a first tensioning arm 273 which is horizontally displaceable relative to the driving wheel and the driven wheel and a second tensioning arm 274. The drive belt is routed around the first and second tensioning arms, and the first and second tensioning arms are positioned to apply pressure to the drive belt to provide tension to the drive belt.SELECTED DRAWING: Figure 22

Description

[Technical Field]

[0001] The present invention relates to automated storage systems and apparatus, and more particularly, but not exclusively, to load handling apparatus operating on a storage system having storage bins in stacks arranged in a grid structure. [Background technology]

[0002] Methods for handling containers stacked in rows have been known for decades. Some such systems, such as those described in U.S. Patent No. 2,701,065 to Bertel, comprise freestanding stacks of containers arranged in rows to reduce the storage volume associated with storing such containers while still providing access to specific containers as needed. Access to a given container is made possible by stacking the given container and providing a relatively complex hoisting mechanism that can be used to remove the given container from the stack. However, the cost of such systems is prohibitive in many situations, and they have been commercialized primarily for storing and handling large shipping containers.

[0003] The concept of using freestanding stacks of containers and providing a mechanism for retrieving and storing specific containers has been further developed, as described, for example, in Cimcorp's European Patent No. 0767113B. European Patent No. '113 discloses a mechanism for retrieving multiple stacked containers using a robotic load handler in the form of a rectangular tube configured to be lowered around the container stack and capable of grasping a container at any level in the stack. In this way, several containers can be lifted from the stack at once. The movable tube can be used to move several containers from the top of one stack to the top of another, or to move containers from the stack to an external location or vice versa. Such a system can be particularly useful when all containers in a single stack contain the same product (known as a single-product stack).

[0004] In the system described in EP '113, the height of the tubes must be at least as high as the height of the largest container stack so that the highest container stack can be extracted in a single motion. Thus, when used in enclosed spaces such as warehouses, the maximum height of the stack is limited by the need to accommodate the load handler tubes.

[0005] EP 1037828B1 (Autostore) describes a system in which a stack of containers is arranged within a frame structure. A system of this type is illustrated diagrammatically in Figures 1 to 4 of the accompanying drawings. Robotic load handling equipment can controllably move around the stack on a track system above the top surface of the stack.

[0006] A load handling apparatus is described in UK Patent Application Publication No. GB2520104A to Ocado Innovation Limited, in which each robotic load handler covers only one grid space, thus allowing a high density of load handlers and therefore a high throughput for a system of a given size.

[0007] In the known robotic picking systems described above, robotic load handling devices controllably move around the top of the stack on a track system that forms a grid. The load handling devices lift accumulation bins from the stack, and the lifted containers contain the inventory items needed to fulfill a customer order. The containers are then transported to a pick station, where the required inventory items can be manually removed from the accumulation bins and placed into shipping containers that form part of the customer order and are manually packed for timely dispatch. At the pick station, the items can also be picked by an industrial robot suitable for such operations, as described, for example, in Ocado Innovation Limited's UK Patent No. GB2524383B.

[0008] As shown in Figures 1 and 2, stackable storage containers known as accumulation storage bins 10 are stacked on top of each other to form stacks 12. The stacks 12 are arranged within a framework 14 in a warehousing or manufacturing environment. Figure 1 is a schematic perspective view of the framework 14, and Figure 2 is a top view showing a single stack 12 of accumulation storage bins 10 arranged within the framework 14. Each accumulation storage bin 10 typically holds multiple products or inventory items, and the inventory items within an accumulation storage bin 10 may be the same or may be of different product types depending on the application. Additionally, accumulation storage bins 10 may be physically subdivided to accommodate multiple different inventory items.

[0009] The framework 14 includes a plurality of upright members 16 supporting horizontal members 18, 20. A first set of parallel horizontal members 18 are arranged perpendicular to a second set of parallel horizontal members 20, forming a plurality of horizontal grid structures supported by the upright members 16. The members 16, 18, 20 are typically fabricated from metal. The accumulation storage containers 10 are stacked between the members 16, 18, 20 of the framework 14, such that the framework 14 prevents horizontal movement of the stack 12 of accumulation storage containers 10 and guides vertical movement of the accumulation storage containers 10.

[0010] The top level of the framework 14 includes rails 22 arranged in a grid pattern across the top of the stacks 12. With further reference to FIGS. 3 and 4 , the rails 22 support a plurality of robotic load handling devices 30. A first set 22 a of parallel rails 22 guides movement of the load handling devices 30 in a first direction (X) across the top of the framework 14, and a second set 22 b of parallel rails 22 arranged perpendicular to the first set 22 a guides movement of the load handling devices 30 in a second direction (Y) perpendicular to the first direction. In this manner, the rails 22 enable movement of the load handling devices 30 in two dimensions in the XY plane, such that the load handling devices 30 can be moved to a position above any of the stacks 12.

[0011] Each load handling apparatus 30 includes a vehicle 32 positioned to travel in the X and Y directions above the stack 12 on the rails 22 of the framework 14. A first set of wheels 34, consisting of a pair of wheels 34 at the front of the vehicle 32 and a pair of wheels 34 at the rear of the vehicle 32, are positioned to engage two adjacent ones of the rails 22 of the first set 22a. Similarly, a second set of wheels 36, consisting of a pair of wheels 36 on each side of the vehicle 32, are positioned to engage two adjacent ones of the rails 22 of the second set 22b. The wheels 34, 36 of each set can be raised and lowered so that either the first set of wheels 34 or the second set of wheels 36 are engaged with the respective set of rails 22a, 22b at any one time.

[0012] When the first set of wheels 34 engages the first set of rails 22a and the second set of wheels 36 is lifted off the rails 22, the wheels 34 can be driven by a drive mechanism (not shown) housed within the vehicle 32 to move the load handling apparatus 30 in the X direction. To move the load handling apparatus 30 in the Y direction, the first set of wheels 34 is lifted off the rails 22 and the second set of wheels 36 is lowered into engagement with the second set of rails 22b. The drive mechanism can then be used to drive the second set of wheels 36 to achieve movement in the Y direction.

[0013] In this manner, one or more robotic load handling devices 30 may move about on top of the stacks 12 on the framework 14, as shown in Figure 4, under the control of a centralized control utility (not shown). Each robotic load handling device 30 is provided with lifting means 38 for lifting one or more accumulation storage containers 10 from the stacks 12 to access the required products.

[0014] The body of the vehicle 32 includes a cavity 40 sized to hold the accumulation bin 10. The lifting means 38 includes a winch means and an accumulation bin gripper assembly 39. The lifting means lifts the accumulation bin 10 from the stack 12 into the cavity 40 in the body of the vehicle 32. When in the cavity 40, the accumulation bin 10 is lifted off the rails below so that the load handling device can move it laterally to a different location on the grid. Upon reaching a target location, such as another stack, an access point in the storage system, or a conveyor belt, the accumulation bin 10 can be lowered from the cavity and released from the gripper assembly 39.

[0015] In this way, multiple products can be accessed from multiple locations in the grid and stack at any one time.

[0016] The above description describes the storage system in relation to, for example, groceries. Figure 4 shows a typical such storage system, which has a number of load handling devices 30 active on a grid above the stacks 12.

[0017] 1 and 4 show accumulation storage containers 10 in stacks 12 within a storage system. It will be appreciated that there may be many accumulation storage containers 10 in any given storage system and many different items may be stored within the accumulation storage containers 10 in the stacks 12. Each accumulation storage container 10 may hold a different category of inventory item within a single stack 12.

[0018] In one system described above, and further in Ocado Innovation Limited's UK Patent Application Publication No. GB2517264A, which is incorporated herein by reference, the storage system comprises a series of accumulation bins 10 which may further comprise delivery containers DT having customer orders placed therein, or which may further comprise accumulation bins 10 having inventory items awaiting picking. These different accumulation bins 10 and combinations thereof may be contained within the storage system and accessed by robotic load handling equipment 30 as described above.

[0019] It will be appreciated that automated or semi-automated storage and retrieval systems are not limited to systems targeted at groceries. For example, the present technology may be applied to shipping, baggage handling, vehicle parking, indoor or hydroponic greenhouses and agriculture, modular buildings, self-storage facilities, cargo handling, haul switchyards, manufacturing facilities, pallet handling, parcel sorting, airport logistics (ULD), and general logistics, to name a few possible applications. It will be appreciated that different types of storage and retrieval systems will have different technical requirements.

[0020] It is against this background that the present invention was conceived. Summary of the Invention

[0021] Aspects of the invention are set out in the accompanying claims.

[0022] One object is to provide a lightweight load handling apparatus. Another object is to provide a low cost load handling apparatus. Another object is to provide a modular load handling apparatus that is easy and / or inexpensive to maintain.

[0023] Another object is to provide load handling equipment that is made primarily from recyclable or environmentally friendly materials.

[0024] A load handling device is provided for lifting and moving stacked storage containers (10) within a grid framework (14) structure, the grid framework (14) structure comprising a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to the first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern with a plurality of grid spaces, wherein the grid is supported by a set of uprights (16) to form a plurality of vertical storage locations below the grid for the containers (10) to be stacked therebetween and guided vertically by the uprights through the plurality of grid spaces. The load handling apparatus comprises a body attached to a first set of wheels (116) arranged to engage a first set of parallel tracks (22b) and a second set of wheels arranged to engage a second set of parallel tracks (22a), and a diverting assembly arranged to raise or lower the first set of wheels and / or lower or raise the second set of wheels relative to the body to engage and disengage the wheels from the parallel tracks, wherein the diverting assembly comprises a compliant mechanism having at least one resiliently deformable member arranged to move under an applied force to raise or lower the wheels.

[0025] A load handling apparatus is provided for lifting and moving stacked storage containers within a grid framework structure, the grid framework structure comprising a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicular to the first set of rails or tracks in a substantially horizontal plane to form a grid pattern with a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations below the grid for containers to be stacked therebetween and guided vertically by the uprights through the plurality of grid spaces, and the load handling apparatus is a body attached to a first set of wheels arranged to engage with the parallel tracks of the first set and a second set of wheels arranged to engage with the parallel tracks of the second set; and a diverting assembly arranged to raise or lower the wheels of the first set and / or lower or raise the wheels of the second set relative to the body to engage and disengage the wheels with the parallel tracks, wherein the diverting assembly comprises a linkage set having a series of members arranged between a traveler and a fixed brace, the traveler arranged to move under an applied force to raise or lower the wheels.

[0026] It will be understood that each member in the series can be identical. Thus, each member will have a similar movement when the traveler is moved relative to the fixed brace. It will be understood that the linkage set can include one member between the traveler and the fixed brace. However, typically, the series will include two or more members or legs. One leg will be located between each end of the fixed brace and the traveler to avoid twisting of the arrangement. Typically, the series will include five members. It will be understood that any number of members can be used according to the requirements of the redirection assembly and the length, and therefore the space, for the traveler and fixed brace.

[0027] The first set of wheels and the second set of wheels may be independently drivable relative to each other, such that when the load handling apparatus is driven, only one set of wheels is engaged with the grid, thereby enabling movement of the load handling apparatus along the track to any point on the grid by driving only the set of wheels engaged with the track.

[0028] An advantage of a diverter assembly with a compliant mechanism or linkage set is that it can reliably engage the appropriate set of wheels to effectively and efficiently maneuver the load handling equipment onto and around the grid in the x and y directions, forward and reverse, so that each grid space can be reached and it can move around other equipment operating on the grid. A further advantage of a compliant mechanism or linkage set for a diverter assembly is that it can be made to be lightweight as a result of taking advantage of material properties.

[0029] The diverting mechanism may be connected to both the first set of wheels and the second set of wheels, such that by selectively operating one set of wheels or the other, the load handling apparatus can be moved to any position on the grid.

[0030] The linkage set can be a series of elastically deformable members with a compliant mechanism, or the linkage set can be a series of pivotally connected rigid members. The series of members can each comprise pivotally connected two-part linkages. The joints between the members of the linkage set are rotationally restricted.

[0031] In this way, the series may rotate about one pivot point, joint, or hinge until it is stopped or limited, and then move about a second pivot point, joint, or hinge. It will be understood that the linkage may include more than two joints. Advantageously, the movement of the series may be designed to manage the force required for the turning function in relation to the position of the wheelset or some other component of the load handling apparatus by adjusting the relative lengths between each component of the two-component linkage and by adjusting the rotation limits. Managing the force required for the turning function makes it possible to manage wear on components of the load handling apparatus. In turn, this results in a more reliable apparatus requiring less maintenance or fewer replacement parts.

[0032] The upper brace may be horizontally displaced relative to the lower brace, and therefore the upper brace may also be referred to as a traveler.

[0033] The compliant mechanism may be stable in a neutral configuration and the compliant mechanism may be stable in at least one other configuration. Similarly, the linkage set may be stable in a neutral configuration and at least one other configuration.

[0034] In this way, the redirection assembly has a "preferred" configuration or position at which the linkage set or compliant mechanism will tend to rest or move to when the deforming force is removed. This allows for selection of the first set of wheels, the second set of wheels, or both the first and second sets of wheels. Advantageously, the load handling apparatus may be arranged to move to a default position. Advantageously, the default position may passively, i.e., without input, automatically place the load handling apparatus in a "safe" state.

[0035] A linkage set or compliant mechanism can be in a stable configuration when a first set of wheels engages the track or when a second set of wheels engages the track. Alternatively, a linkage set or compliant mechanism can be in a stable configuration when a first set of wheels engages the track and a second set of wheels engages the track. Thus, a linkage set or compliant mechanism can have three stable configurations: a stable configuration for each set of wheels, and a stable "parked" configuration in which both the first and second sets of wheels are engaged with the track.

[0036] The diverter assembly may include at least one linkage set or compliant mechanism for each set of wheels. These linkage sets or compliant mechanisms may be mechanically connected to move in unison between them. The mechanical connection may be a belt linking two or more linkage sets, and optionally, the belt circumnavigates the body of the load handling equipment. Alternatively, the mechanical connection may be a chain. Thus, coordinated deployment of each set of wheels may be ensured. This may prevent tilting of the load handling equipment body, thereby helping to keep the load handling equipment envelope within a single spatial tolerance during diverter operations. This, in turn, reduces the risk of collision with other load handling equipment operating on adjacent tracks. It will be understood that any number of linkage sets or compliant mechanisms may be used to enable the diverter assembly to operate in a desired manner, as described herein. It will be appreciated that a first opposing pair of sides of the load handling apparatus should move together and a second opposing perpendicular pair of sides should move in opposition to the first pair of sides, and therefore the linkage sets of the compliant mechanisms on the second pair of sides may be reversed relative to the compliant mechanisms on the first pair of sides.

[0037] The at least one elastically deformable member may be a hinge, and the compliant mechanism may comprise a series of trunk portions attached to the upper and lower braces through the hinges. The hinges may comprise branch portions or spring portions. It will be understood that any other type of hinge may be used that has the necessary characteristics to achieve the desired behavior of the compliant mechanism.

[0038] Thus, the compliant mechanism is arranged to preferentially bend or flex at specific points on the geometry. This, in turn, promotes specific mechanical or dynamic mechanical behavior from the compliant mechanism. The hinge can be designed with a thinner section than the trunk.

[0039] As mentioned above, a compliant hinge may be replaced with another type of hinge. For example, the "living" hinge of a compliant mechanism may be replaced with a pivotally connected rigid member arranged to replicate the same behavior. The pivotal connection may be a hinge. The pivotally connected rigid member may be a linkage set.

[0040] Each linkage set or compliant mechanism may include at least one trunk section having a first type of hinge and at least one trunk section having a second type of hinge.

[0041] In this way, complex behaviors of a linkage set or compliant mechanism can be achieved. A first type of hinge can exhibit one type of behavior, a second type of hinge can exhibit a second, different behavior, or a linkage set or compliant mechanism using a series of posts or trunks, each with different behavior characteristics, can exhibit a combination of behavior characteristics.

[0042] In use, and for example, when the upper brace or traveler is moved in a first direction relative to the lower brace, a trunk portion having a first type of hinge may engage with the upper and lower braces in an x-direction stable configuration, and / or when the upper brace or traveler is moved in a second direction relative to the lower brace, a trunk portion having a second type of hinge may engage with the upper and lower braces in a y-direction stable configuration.

[0043] The diverting mechanism may be driven by a single motor.

[0044] In this way, a single motor can be used to change the direction of movement of the load handling apparatus. It will be appreciated that the motor can be replaced with any means of activation, such as, for example, solenoids, hydraulic means, pneumatic means, servo means, solid state actuation means, etc. Advantageously, this can reduce the overall cost and weight of the load handling apparatus.

[0045] The diverting mechanism may be driven by more than one motor. The diverting mechanism may be driven by a motor for each respective compliant mechanism.

[0046] In this way, the load handling equipment may have some redundancy so that even if there is a partial failure of the load handling equipment, the load handling equipment may continue to operate, thus avoiding a complete failure of the maneuverability of the load handling equipment on the grid. Advantageously, a more robust turning mechanism is provided. Advantageously, this reduces downtime of individual load handling equipment as well as the entire storage and retrieval system.

[0047] The linkage set or compliant mechanism(s) may be made from plastic, polymer plastic, thermoset plastic, thermoplastic, metal, aluminum, aluminum alloy, iron, iron alloy, steel, steel alloy, magnesium, magnesium alloy, titanium, titanium alloy, zinc, zinc alloy, fiber reinforced composite, carbon fiber, graphite fiber, glass fiber, natural fiber, plant fiber, plastic fiber, paper, cardboard, rubber, epoxy resin, or nylon.

[0048] The linkage set or compliant mechanism(s) may be 3D printed. In this manner, it may be possible to achieve geometries that are not possible with more traditional forms of manufacturing. Advantageously, the linkage set or compliant mechanism may be printed on-demand or at a 3D printing facility near where the part is needed, thereby minimizing the logistical costs of transporting the parts to where they are needed. It will be understood that 3D printing as referred to herein may more generally be referred to as additive manufacturing, and involves the layer-on-layer addition of material.

[0049] The linkage set or compliant mechanism(s) may be substantially topologically optimized. In this manner, the linkage set or compliant mechanism may be optimized to reduce the total amount of material used. Alternatively, the linkage set or compliant mechanism may be optimized to stay within certain stress limits to ensure that the linkage set or compliant mechanism operates below the fatigue limit within the operating temperature range.

[0050] It will be understood that one set of wheels may be fixed relative to the framework or body of the load handling apparatus, while the other set of wheels may be raised and lowered relative to the body of the load handling apparatus. Alternatively, it will be understood that neither set of wheels may be fixed relative to the body of the load handling apparatus, with the first and second sets of wheels being arranged to move in unison in opposite vertical directions relative to the body of the load handling apparatus. Thus, it will be understood that the diverting mechanism may be attached or connected to both the first set of wheels and the second set of wheels, or the diverting mechanism may be attached to only one set of wheels.

[0051] According to another embodiment of the present invention, there is provided a method of changing the direction of travel of a load handling apparatus, the method comprising the steps of applying a force F1 in a first direction to a traveler of a diverting assembly to move the linkage set or compliant mechanism to an x-stable configuration, or applying a force F2 in a second direction to the traveler of the diverting assembly to move the linkage set or compliant mechanism to a y-stable configuration, or removing the force applied to the traveler of the diverting assembly to move the linkage set or compliant mechanism to a neutral or rest configuration with no elastically stored energy.

[0052] Thus, the compliant mechanism can be moved between stable state configurations.

[0053] The method may further comprise the steps of receiving a signal from a centralized control facility; and controlling the turning assembly based on the received signal to (a) engage a first set of wheels with the track, (b) engage a second set of wheels with the track, or (c) engage the first and second sets of wheels with the track to park the load handling apparatus, and optionally, when the first or second set of wheels is engaged with the track, driving the wheels of that set in a forward or reverse direction to steer the load handling apparatus to a position on the grid as determined by the centralized control facility.

[0054] Thus, the diverting assembly may be controlled by a centralized control facility and used to engage sets of wheels as determined by the centralized control facility. Once a (single) set of wheels is engaged, the centralized control facility may drive the wheels to steer the load handling apparatus. Alternatively, the load handling apparatus may be "parked" by simultaneously engaging both sets of wheels.

[0055] The load handling apparatus may further comprise means for sensing a position on the grid. The load handling apparatus may further comprise means for lifting a storage container. The load handling apparatus may further comprise means for transporting the lifted storage container to a position on the grid. The load handling apparatus may further comprise means for identifying multiple storage containers. The load handling apparatus may further comprise means for identifying a single storage container. The load handling apparatus may be autonomously mobile without continuous direction from a centralized control utility. The load handling apparatus may be remotely piloted under control of a storage system. The load handling apparatus may further comprise means for communicating a signal to the centralized control utility and may be mobile under control of the centralized control utility. The load handling apparatus may further comprise means for providing power to the turning assembly. The load handling apparatus may further comprise a drive assembly. The load handling apparatus may have wheels driven by belts. The load handling apparatus may further comprise identification means.

[0056] A method for altering engagement between a set of wheels and a track of a load handling apparatus is provided, wherein the load handling apparatus operates on a grid framework (14) structure comprising the track, the method comprising applying a force F1 in a first direction to a traveler of the diverting assembly to move the linkage set or compliant mechanism to an x-stable configuration, or applying a force F2 in a second direction to the traveler of the diverting assembly to move the linkage set or compliant mechanism to a y-stable configuration, or removing the force applied to the traveler of the diverting assembly to move the linkage set or compliant mechanism to a neutral configuration.

[0057] The method may further include receiving a signal from a centralized control facility and controlling the diverting assembly based on the received signal to (a) engage a first set of wheels with a first set of parallel tracks, (b) engage a second set of wheels with a second set of parallel tracks, or (c) engage the first and second sets of wheels with the first and second sets of parallel tracks to park the load handling apparatus.

[0058] Here, when the first or second set of wheels is engaged with the track, the method may further comprise the step of driving that set of wheels in a forward or reverse direction to steer the load handling apparatus to a position on the grid as determined by the centralized control facility.

[0059] A kit of parts for modular assembly of load handling equipment is provided, the kit comprising at least one diverting assembly linkage set or compliant mechanism.

[0060] The kit may further comprise a transfer belt and at least two diverting assembly linkage sets or compliant mechanisms; at least one diverting motor; and / or linkages for connecting the diverting assembly to the first set of wheels and the second set of wheels.

[0061] At least one part of the kit may be 3D printed.

[0062] The kit of parts may further comprise at least one of a set of wheels, a drive assembly, a gripper assembly, a lifting assembly, a communication system, and / or sensor means.

[0063] A grid-based storage and retrieval system is provided, comprising: a grid framework (14) structure comprising a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to the first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces; wherein the grid is supported by a set of uprights (16) to form a plurality of vertical storage locations below the grid such that containers (10) are stacked therebetween and guided vertically by the uprights through the plurality of grid spaces; at least one load handling device operating on the grid framework structure; and a centralized control utility for controlling the at least one load handling device(s).

[0064] The at least one load handling equipment may further comprise a communications means, the centralized control utility of the storage system comprising communications means for communicating with the communications means on the at least one load handling equipment.

[0065] A centralized control utility remotely monitors the status of at least one load handling device.

[0066] If a malfunction and / or failure of the load handling equipment is detected, the load handling equipment may be instructed to move to the edge of a maintenance area or grid using non-malfunctioning and non-failed means.

[0067] The centralized control utility may communicate with at least one load handling device operating on the grid to command the load handling device to move to a particular location on the grid.

[0068] Additionally, the load handling equipment may be instructed to lift the container from the stack and move the container to another location on the grid, and / or the load handling equipment may be further instructed to lower the container to a stack position below the grid.

[0069] A load handling device is provided for lifting and moving stacked storage containers (10) within a grid framework (14) structure, the grid framework (14) structure comprising a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to the first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights (16) for the containers (10) to be stacked therebetween. and uprights to form a plurality of vertical storage locations below the grid such that the load handling device is guided vertically through the plurality of grid spaces, and the load handling device comprises a body attached to a first set of wheels (116) arranged to engage with the first set of parallel tracks (22b) and a second set of wheels (118) arranged to engage with the second set of parallel tracks (22a), wherein the first and second sets of wheels (116, 118) comprise wheels having spokes connecting a rim to a hub, the wheels being at least partially elastically deformable.

[0070] The rim and wheel hub may be made of a stiff material relative to the spoke material. The wheel spokes may be arranged in a mesh. A portion of the wheel spoke mesh may be compressible.

[0071] The wheel may include two or more layers, where a first type layer having radial spokes may be stacked with at least one second type layer having curved spokes. Thus, the wheel may include a wheel assembly. The curved spokes may include a first set curved in a clockwise direction and a second set curved in a counterclockwise direction. The first type layer may be sandwiched between two second type layers.

[0072] Advantageously, the wheels are designed to be lightweight, provide some shock absorption, provide some suspension for the load handling equipment, and reduce tire wear. An additional benefit of this arrangement is that the outer layer can flex out of plane, allowing the wheel to accommodate narrowing track widths, for example, at misaligned sections and transitions of the track. The out-of-plane bending allows the wheel to collapse and momentarily become narrower in scenarios where a less deformable wheel might try to lift itself off the track and derail.

[0073] A wheel may exhibit a combination of properties, with the properties of each of these layers contributing to the overall properties of the wheel. Each layer may be designed to optimize a particular property, in which case the layered or composite arrangement or wheel exhibits all of the properties embodied by the layers.

[0074] In this way, the wheels exhibit properties that advantageously provide stiffness and strength in a particular direction, yet are able to absorb some vibration as they move on the track. In particular, the spoke network design may be such that the torsional stiffness is kept within a particular range, thereby avoiding imprecision in the movement of the load handling equipment.

[0075] In this way, the wheels can generate good traction with the track and minimize wheel slip, which allows the load handling equipment to be more precisely positionally controlled on the grid as the drive motion results in more consistent and predictable movement of the load handling equipment.

[0076] The rim of the second type of layer may include a groove for receiving an O-ring.

[0077] The O-ring provides the contact point between the wheel and the track. Thus, the second type of layer may have an O-ring that provides the track-wheel interface. The O-ring is typically made from rubber. This may provide a certain amount of suspension for the wheel. The O-ring is readily available and can be easily replaced. It will be appreciated that any suitable material and arrangement may be used to provide traction and provide the contact point between the wheel and the track. For example, a rubber strip may be attached to the rim.

[0078] The rim of the wheel may include additional grooves for receiving additional O-rings, for example, the wheel may include two, three or more grooves for receiving O-rings.

[0079] Having the option to provide additional O-rings on the wheel across the width or depth of the wheel provides an opportunity to increase the rubber contact between the wheel and the track. It will be appreciated that the wheel may necessarily require modification in other respects to accommodate the additional space around the wheel rim that the additional O-rings require. For example, it may be necessary to provide a different or modified drive arrangement.

[0080] The additional O-rings and the proportionally additional contact area they provide advantageously provide a wheel that may be able to provide sufficient grip under heavier load conditions. In this way, the wheel may be used with load handling equipment carrying greater loads. This, in turn, may increase the efficiency of storage and retrieval systems, for example.

[0081] The first type of layer may be a pulley and may have a smaller diameter than the second type of layer, thereby creating a channel that can receive a drive belt, and the rim of the first type of layer may include cog teeth for cooperating with the drive belt.

[0082] In this way, the first type layer may be positioned so that it does not contact or interface with the track but instead is part of the drive train. Although the first type layer does not contact or interface with the track and therefore does not support the load handling device, the first type layer may provide axle drive for the wheels and support the second type layer. Thus, the first type layer of the assembly may be part of the hub to which the second type layer is attached for track-wheel contact.

[0083] In this way, the first type of layer can be driven by a drive belt. The drive belt can mesh with the first type of layer or pulley and be used to drive the second type of layer or wheel of the load handling device to provide maneuverability. The arrangement of the drive belt in a groove or channel ensures that the drive belt stays in the correct position to mesh with the cog. Having the wheel driven by the drive belt pulley can mean more design freedom for the design of the wheel itself. The combined properties of each of these layers, along with the direct drive provided by the first type of layer pulley / hub, can advantageously allow the wheel to be driven with positional precision while being resilient to step changes in the track, for example. In this way, the wheel can allow the load handling device to be driven to a specific location on a grid framework having multiple grid spaces.

[0084] The sides of the rim may be angled relative to the plane of the wheel.

[0085] The outermost surface of the wheel may be angled. In this way, the wheel is less likely to derail as it travels along the track. The angle of the rim face or side of the rim may guide the wheel back into position and into contact with the track if the wheel jumps over a bump in the track, for example, at the transition between grid spaces.

[0086] The hub may include a bearing for rotatably mounting the wheel to an axle on the load handling device body.

[0087] The wheel may be made from plastic, polymer plastic, thermoset plastic, thermoplastic, metal, aluminum, aluminum alloy, iron, iron alloy, steel, steel alloy, magnesium, magnesium alloy, titanium, titanium alloy, zinc, zinc alloy, fiber reinforced composite, carbon fiber, graphite fiber, glass fiber, natural fiber, plant fiber, plastic fiber, paper, cardboard, rubber, epoxy resin, or nylon.

[0088] In particular, the spoke material is polyurethane or nylon, the hub and rim material is nylon, and the O-ring is rubber.

[0089] The wheel can be 3D printed and can be substantially topologically optimized.

[0090] In this way, wheels can be designed for specific properties, and they can be printed at or near where they are needed, avoiding complex supply chains.

[0091] A drive belt assembly for a load handling apparatus is provided, the drive belt assembly comprising: a drive belt; a drive wheel; one or more driven wheels; and tensioning means comprising: a first tensioning arm having a fixed end above an elbow and a rotatable distal end pivotally mounted at the elbow, wherein the first tensioning arm is horizontally displaceable relative to the drive wheel and the driven wheel; and a second tensioning arm, wherein the drive belt is routed around the first and second tensioning arms, and the first and second tensioning arms are arranged to apply pressure to the drive belt to impart tension to the drive belt.

[0092] A drive belt assembly, wherein the driven wheel may be vertically movable relative to the drive wheel between a raised configuration and a lowered configuration, and wherein the tensioning means may have respective configurations corresponding to the raised and lowered configurations of the driven wheel, the tensioning means being movable therebetween.

[0093] A load handling apparatus is provided for operating on a grid framework storage structure, the grid framework storage structure comprising a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to the first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights (16) for allowing containers (10) to be stacked therebetween and for supporting the plurality of grid spaces by the uprights. A plurality of vertical storage locations are formed below the grid so as to be guided vertically, and the load handling device comprises a body mounted on a first set of wheels (116) arranged to engage with a first set of parallel tracks (22b) and a second set of wheels arranged to engage with a second set of parallel tracks (22a), wherein the first set of wheels (116) and the second set of wheels (118) are driven by respective drive belts, and the first set of wheels (116) and the second set of wheels (118) are driven wheels.

[0094] The load handling apparatus may include four drive belt assemblies located on each side of the load handling apparatus for driving respective driven wheels.

[0095] The load handling apparatus may further comprise a diverting assembly arranged to raise or lower the first set of wheels and / or lower or raise the second set of wheels relative to the drive wheels to engage and disengage the wheels from the parallel tracks, wherein tensioning means on the drive belt assembly are arranged to apply pretension to the drive belt when the driven wheels are being moved between the raised, lowered and parked configurations.

[0096] In this manner, the drive belt assembly can be pretensioned by the tensioning means to ensure engagement between the drive belt, the drive wheel, and the driven wheel. It will be appreciated that without the tensioning means, the path length of the drive belt would change as the wheel moves between the lowered and raised positions, potentially becoming slack and slipping. The drive belt assembly, and more specifically the tensioning means, is arranged to compensate for the change in belt path length so that the path length of the drive belt remains substantially the same, ensuring that the belt is tensioned as necessary to remain in contact with the drive wheel and the driven wheel, as required for drive. When the driven wheel is in the raised position, the path length around the tensioning means increases the path length of the drive belt as the belt is routed over the elbow of the first tensioning arm to compensate for the reduction in vertical distance between the traveler mount and the wheel. Advantageously, the tensioning means substantially prevents the drive belt from becoming slack. Advantageously, the tensioning means can ensure that the drive belt is in a tensioned state before it is driven, thus avoiding slippage of the belt on the driven pulley. Without pretensioning, the drive belt can slip out of engagement with the driven and driving wheels, or can wear due to improper engagement with the driving wheels.

[0097] It will be appreciated that the change in path length of the drive belt as the diverting assembly moves may not be linear and will depend on the geometry of the diverting assembly.

[0098] Pretension is the amount of tension placed on the drive belt by the tensioning means before the drive belt is driven to ensure that the belt does not slip against the pulley. During operation, when the belt is driven, the drive belt is in a higher tension state to transfer force from the drive pulley to the driven wheel. The speed at which the belt travels is a function of the load on the system and the motor.

[0099] It will be appreciated that the drive means may be a chain drive instead of a drive belt. In some arrangements, the drive belt may be toothless.

[0100] A drive belt assembly, wherein the movement between the driven wheel and tensioning means arrangement can be mechanically adjusted.

[0101] The drive belt assembly may further comprise a diverting assembly arranged to raise or lower the driven wheel relative to the drive wheel, wherein tensioning means of the drive belt assembly is arranged to apply pretension to the drive belt when the driven wheel is being moved between the raised, lowered and parked configurations.

[0102] A drive belt assembly, wherein the tensioning means may be mechanically linked to the diverting mechanism.

[0103] The tensioning means may be arranged to move with the driven wheel, in this way the drive belt is always tensioned by the tensioning means, assuming the system is functional and dependent on wheel position.

[0104] A drive belt assembly, wherein the movement of the driven wheel and the movement of the tensioning means in the vertical direction can be actuated by the same actuator.

[0105] A drive belt assembly, wherein the tension that can be applied to the drive belt varies depending on the position of a first tensioning arm and / or a second tensioning arm.

[0106] A drive belt assembly in which the peak force required to change direction can be at a different time than the peak force required to apply tension.

[0107] The direction-changing motor for enabling the vertical movement of the drive wheel can also be used to move the tensioning means. Advantageously, no additional motor is required for the tensioning means.

[0108] It will be appreciated that the force required to operate the diverting mechanism and the force required to operate the tensioning means will vary over time as operation occurs. As a result of the geometric design of the tensioning means, the peak force required for the tensioning means may occur slightly before or after the peak force required for the diverting assembly. In this way, the additional load applied to the actuation motor by the tensioning means is managed to occur primarily outside of the momentary times when high loads are applied to the actuation motor by the diverting assembly, and therefore the required motor size is not increased by the tensioning means.

[0109] It will be appreciated that the diverting assembly may tension the drive belt due to changes in the vertical distance between the driven wheel and the driving wheel. In some cases, the distance between the wheel mounting point and the "middle halo" or upper brace / traveler mounting point may temporarily be longer than when the wheel is in the driving position. It will be appreciated that the belt will need to be stretched over this "bump" to overcome it, requiring a larger motor. The belt may break. It will be appreciated that the tensioning means may compensate for this by tensioning the belt only after the "bump." Thus, by following a belt path with complex, interacting diverting and belt tensioning arrangements, it may be possible to avoid belt wear and strain on the motor.

[0110] The drive belt assembly may further comprise sensing means for monitoring belt tension and, optionally, means for adjusting belt tension.

[0111] The drive belt assembly may further comprise sensing means for determining malfunction or failure of the drive belt.

[0112] In this way, the condition of the drive belt and its tension can be monitored. If the belt stretches slightly, the path length of the drive belt can be increased by a similar amount by adjusting the belt adjustment means. This allows the "rest" tension and belt path or route to be adjusted without having to remove the belt from the load handling apparatus to replace or adjust it. Furthermore, this allows for fine adjustment of the belt. Belt adjustment may be possible between drive operations while the load handling apparatus is operating on the storage system grid. Of course, if the belt stretches significantly, it may need to be replaced during maintenance of the load handling apparatus in a maintenance area. Furthermore, the sensing means may also be able to detect if there is a failure of the drive belt or drive system. During operation, the load handling apparatus typically has a drive belt assembly and tensioning means on each side. Thus, even if the belt on one side fails, the load handling apparatus may be sufficiently operable to return to the edge of the grid or maintenance area for repair by using the other set of driven wheels, rather than getting stuck on the grid and requiring at least a partial grid closure to recover.

[0113] A load handling device is provided for lifting and moving stacked storage containers (10) within a grid framework (14) structure. The load handling device comprises a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to the first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights (16) to form a plurality of vertical storage locations below the grid for containers (10) to be stacked therebetween and guided vertically through the plurality of grid spaces by the uprights, the load handling device comprising: a body attached to a first set of wheels (116) arranged to engage the first set of parallel tracks (22b) and a second set of wheels (118) arranged to engage the second set of parallel tracks (22a); and a gripper assembly for latching onto a storage container (10), wherein the gripper assembly comprises a deformable flexure mechanism movable between a locked configuration and an unlocked configuration.

[0114] The gripper assembly may be self-locking.

[0115] The load handling device can grip the storage container and lift the storage container. The gripper assembly is stable in at least two configurations and self-locks in at least a locked configuration. The gripper operates below the fatigue limit of the material and is repeatedly movable between these positions. In this way, the load handling device can firmly and reliably grip the storage container for lifting and moving the storage container.

[0116] The bistable flexure may include an actuator, two or more gripper arms having hook ends, and a number of hinge arrangements corresponding to the number of gripper arms, where each hinge arrangement is deformable and connects a respective gripper arm to the actuator. The hinge arrangement includes a fulcrum, with first and second deformable sections connected to respective ends of the fulcrum. The fulcrum is substantially triangular. In the locked configuration, the fulcrum engages the gripper arms and the compliant mechanism is open or widened, and in the released configuration, the first and second sections of the hinge are flexed and the compliant mechanism is closed or narrowed.

[0117] The hook ends of the gripper arms allow the gripper to hook onto a cooperating portion of the storage container, and the fulcrum means that the flexure cannot move beyond the stable locked position without failure of the gripper. Thus, the configuration of the gripper assembly itself ensures that the gripper can be securely secured to the storage container for the purposes of lifting and moving the storage container.

[0118] The hinge arrangement may be connected to the gripper arm spaced from the hook end, and the fulcrum may extend above a line between the first and second hinge arrangements, or the fulcrum may extend below a line between the first and second hinge arrangements. The gripper assembly may include two or more flexure mechanisms. The gripper assembly may include four flexure mechanisms.

[0119] It will be understood that the particular arrangement will depend on the intended use of the gripper assembly, and the intended scope is not limited to the particular examples disclosed herein.

[0120] The load handling apparatus may further comprise means for lifting the storage container, wherein the means for lifting the storage container comprises a gripper plate and the gripper assembly is attached to the gripper plate. The means for lifting the storage container may be releasably attachable to a framework or body of the load handling apparatus. Lifting tapes may be attached to the gripper arms.

[0121] The flexure mechanism can be 3D printed.

[0122] A method of using a gripper assembly of a load handling device is provided, wherein a flexure is inserted into a cooperating recess in a container, and when a lifting force is applied to the container by the gripper assembly, the flexure engages the container and moves to a locked configuration.

[0123] When the compliant mechanism is in the locked configuration and an actuation force is applied to the gripper assembly, the compliant mechanism can move from the locked configuration to the released configuration.

[0124] A kit of parts for modular assembly of load handling equipment is provided, the kit including at least one gripper assembly flexure.

[0125] Other variations and advantages will become apparent from the following description.

[0126] The invention will now be described with reference to the accompanying schematic drawings. [Brief explanation of the drawings]

[0127] [Figure 1] FIG. 1 is a schematic perspective view of a frame structure for accommodating multiple stacks of accumulation storage containers in a storage system. [Figure 2] FIG. 2 is a schematic plan view of a portion of the frame structure of FIG. [Figure 3a]FIG. 3(a) is a schematic rear perspective view of one form of robotic load handling apparatus for use with the frame structure of FIGS. 1 and 2. [Figure 3b] FIG. 3(b) is a schematic front perspective view of one form of robotic load handling apparatus for use with the frame structure of FIGS. 1 and 2. [Figure 3c] Figure 3(c) is a schematic perspective view of the known load handling device in use, lifting a collection bin. [Figure 4] FIG. 4 is a schematic perspective view of a known storage system comprising a plurality of load handling devices of the type shown in FIGS. 3(a), 3(b) and 3(c) mounted on the frame structure of FIGS. 1 and 2. [Figure 5] FIG. 5 is a schematic diagram of a load handling apparatus. [Figure 6] 6(a)-(c) are schematic diagrams of a compliant mechanism linkage set for use in engaging first and second sets of wheels of a load handling apparatus as part of a diverting assembly according to one form of the present invention. [Figure 7] 7(a)-(c) are perspective views of the load handling apparatus showing the compliant mechanism and wheel positions in similar positions to those shown in FIG. [Figure 8] 8(a)-(c) illustrate examples of compliant mechanisms in neutral or rest configurations with various flexure hinge arrangements for use as part of a redirection assembly. [Figure 9] 9(a) and 9(b) illustrate a compliant mechanism in first and second stable configurations for use in a redirection assembly. [Figure 10] FIG. 10(a) is a plan view and FIG. 10(b) is a perspective view of a wheel having spokes for use on a load handling device. [Figure 11] FIG. 11(a) is a plan view and FIG. 11(b) is a perspective view of a first layer type wheel for use on a load handling device. [Figure 12] FIG. 12(a) is a plan view and FIG. 12(b) is a perspective view of a second layer type wheel for use on a load handling device. [Figure 13] Figures 13(a) and (b) show schematic force diagrams of part of a second layer type wheel for use on a load handling device. [Figure 14] FIG. 14 shows the wheel chassis. [Figure 15] FIG. 15 shows a drive assembly for use with a set of wheels. [Figure 16] FIG. 16 shows the lifting assembly. [Figure 17] FIG. 17 shows an alternative arrangement of the lifting assembly. [Figure 18] FIG. 18(b) shows a schematic view of the gripper assembly in a locked configuration, and FIG. 18(c) shows a schematic view of the gripper assembly moving from the locked configuration to the released configuration. [Figure 18a] FIG. 18a shows a schematic diagram of the gripper assembly in a locked configuration. [Figure 19] FIG. 19(a) shows a schematic diagram of the gripper assembly in a locked configuration, and FIG. 19(b) shows a schematic diagram of the gripper assembly in a released configuration. [Figure 20] Figures 20(a) and (b) illustrate the load handling apparatus with and without a raised container. [Figure 21] FIG. 21 shows a plan view of the drive assembly with tensioning means. [Figure 22] FIG. 22 shows a perspective view of the drive assembly illustrated in FIG. [Figure 23] Figures 23a to 23c are plan views of the drive assembly and tensioning means, with Figure 23(a) showing the wheel in a position to engage with the track, Figure 23(b) showing the wheel in a neutral or stationary position, and Figure 23(c) showing the wheel raised, i.e., not engaged with the track. [Figure 24] Figures 24a-c are plan views of the drive assembly and tensioning means illustrating the relative positions of the tensioning means and wheels on a load handling apparatus resting on a surface, with Figure 24(a) showing the y-direction wheel lowered into a position where it engages the surface and the x-direction wheel raised to disengage from the track, Figure 24(b) showing the wheels in a neutral or resting position where both the x-direction wheel and the y-direction wheel are engaged with the track, and Figure 24(c) showing the x-direction wheel lowered and the y-direction wheel raised. [Figure 25] FIG. 25 illustrates a plan view of the load handling apparatus showing the drive motor arrangement. [Figure 26] Figure 26(a) is a top view of a wheel with spokes for use on a load handling apparatus, and Figure 26(b) is a perspective view of a wheel with spokes for use on a load handling apparatus. [Figure 26c] FIG. 26c is a side view of a wheel with multiple O-rings as a tire. [Figure 27] Figures 27(a) and (b) show schematic force diagrams of a portion of a grating layer type wheel. [Figure 28] FIG. 28(a) shows a plan view of a hub motor suitable for fitting a wheel of the type illustrated in FIG. 26, and FIG. 28(b) shows a side view of the hub motor. [Figure 29] FIG. 29(a) shows a plan view of a wheel of the type illustrated in FIG. 26 fitted to a hub motor of the type illustrated in FIG. 28, and FIG. 29(b) shows a side view thereof. [Figure 30] FIG. 30 illustrates a top view of a rigid linkage set as part of a redirection assembly in accordance with one embodiment of the present invention. [Figure 31] 31(a)-(d) show exploded parts of a single two-piece linkage of a rigid linkage set of the type shown in FIG. [Figure 32]FIG. 32 shows a perspective view of the rigid linkage set shown in FIG. [Figure 33a] Figure 33a shows the rigid linkage set of Figures 30-32 with the wheels in a parked position (Figure 33a). [Figure 33b] Figure 33b shows the rigid linkage set of Figures 30-32 with a second wheel set engaged (Figure 33b). [Figure 33c] Figure 33c shows the rigid linkage set of Figures 30-32 with the first wheel set engaged (Figure 33c). [Figure 34] FIG. 34 shows a side view of the wheel mount and linkage. [Figure 35] FIG. 35 shows an isometric view of the wheel mount and linkage. [Figure 36] Figures 36(a) and (b) show graphs of drive belt tension versus wheel height for the turning function. [Figure 37] FIG. 37 shows an exploded view of the wheel showing each of the component parts. [Figure 38] FIG. 38(a) shows a plan view of the assembled wheel, and FIG. 38(b) shows a cross-sectional view of the wheel taken along line XX. [Figure 39] FIG. 39 shows the spring layer of the wheel in (a) plan view and (b) perspective view. [Figure 40] FIG. 40 shows a plan view of the wheel pulley layer. [Figure 41] FIG. 41 shows the wheel contact plate as a plan view (a) and a perspective view (b). DETAILED DESCRIPTION OF THE INVENTION

[0128] As used herein, the term "comprise" and its derivatives are intended to have an inclusive, rather than exclusive, meaning. For example, "x comprises y" is intended to include the possibility that x includes one and only one y, multiple ys, or one or more ys and one or more other elements. When an exclusive meaning is intended, the phrase "x consists of y" is used to mean that x includes only y and nothing else.

[0129] As used herein, the phrase "movement in the n-direction," where n is one of x, y, and z (and related phrases) is intended to mean movement substantially along or parallel to the n-axis in either direction (i.e., toward the positive end of the n-axis or toward the negative end of the n-axis).

[0130] As used herein, the term "connect" and its derivatives are intended to encompass the possibilities of direct and indirect connections. For example, "x is connected to y" is intended to encompass the possibilities of x being directly connected to y with no intervening components, and the possibilities of x being indirectly connected to y with one or more intervening components. Where a direct connection is intended, the terms "directly connected," "direct connection," or similar are used. Similarly, terms such as "support," "mount," and their derivatives are intended to encompass the possibilities of direct and indirect contact.

[0131] Some terms, such as "load handling equipment," "vehicle," and "bot," are used interchangeably herein. Similarly, the terms "body," "frame," and "skeleton" of load handling equipment, "rails" and "tracks" of a storage frame, and "accumulation bin," "container," or "tote" of a storage system may be used interchangeably. A "DT" or "delivery tote" is a tote that contains a completed or partially completed order. A "ST" or "storage tote" is a tote that contains an item or delivery tote that is being stored in a storage and retrieval system.

[0132] As is commonly understood, a compliant mechanism converts input forces and displacements into output forces and displacements through elastic deformation of the mechanism body. The deformation and displacement, or movement, of a compliant mechanism is determined by the material properties, shape, and geometry of the mechanism. As a compliant mechanism deforms due to the application of a force, elastic energy is stored in the compliant mechanism. When the force is removed, the compliant mechanism will typically return to its original shape or configuration by releasing the stored elastic energy. The stored elastic energy may be stored in the material itself, or the elastic energy may be stored in the mechanism as a result of the shape or geometry of the mechanism.

[0133] The choice of material for a compliant mechanism is important to ensure that the mechanism behaves as intended. For example, a rubber material would introduce losses into the mechanism system because elastic energy can be dissipated as heat energy, while a rigid material may be unsuitable because it cannot bend without breaking.

[0134] The manufacturing method can also affect the behavior and properties of a compliant mechanism. For example, 3D printing techniques can be used to manufacture complex shapes and geometries.

[0135] Typically, when no force is applied to a compliant mechanism and no elastic energy is stored, the compliant mechanism is described as being "at rest" or in a neutral position.

[0136] Compliant mechanisms often include a linkage of rigid members connected together at rotary or flexural joints.

[0137] In some forms, compliant mechanisms can be "distributed." Distributed compliant mechanisms can be designed by selectively removing material from an allowable build volume in conjunction with modeling techniques such as the Finite Element Method, which can determine how a given volume deforms under load. Each time material is removed from the allowable build volume, the resulting mapping between input load and output deflection and loads can be predicted, and an evaluation of the suitability of a given shape for the task at hand can be performed. Many shapes can be iteratively tested with topology optimization algorithms. The resulting shapes typically do not have explicit flexure hinges, but rather have the added benefit of spreading deformation throughout the shape, which reduces surface stresses in the material under load conditions and alleviates fatigue in the part.

[0138] Alternatively, several components may work together to form a compliant mechanism.

[0139] A variety of compliant mechanisms may be used as part of the load handling apparatus described herein.

[0140] A compliant mechanism topology can closely mimic a rigid linkage with a flexure pivot, and thus the rigid linkage can replace one or more of the compliant mechanisms described herein.

[0141] Advantageously, compliant mechanisms can be used to provide a "default" position to which the mechanism will return without external input. The default position can be designed to be a "safe" position. Advantageously, this can be designed into the device as a safety feature. For example, if control of the system or part of the system is temporarily lost, devices operating in the system can return to their default safe position until control and operation is restored. This could, for example, be to place the load handling apparatus in a "parked" configuration so that it cannot be moved until the problem is resolved.

[0142] Other uses and advantages of the compliant mechanism will become apparent from the following description.

[0143] As is commonly understood, topology relates to the geometric dimensions and properties of an object's shape.

[0144] The object may be designed to meet mechanical requirements for loading and ensure that the components of the assembly or mechanism are free to move as needed.

[0145] Artificial intelligence (AI) (or in some cases, machine learning (ML)) computing techniques may be used to meet structural and mechanical and dynamic loading requirements using specific materials while aiming to achieve certain secondary goals, such as minimizing overall weight, staying within certain stress limits, considering specific thermal properties of the material, etc. Thus, after designing for a specific function, the part may undergo a process of "topology optimization" using AI to create often unique shapes that would not have been designed otherwise. For example, the AI ​​may be given instructions such as, "While performing function Z, do not bend fitting 1 beyond X, nor have it have stress beyond Y."

[0146] Various parts of a load handling device may be suitable for undergoing a topology optimization process. Example parts include, but are not limited to, corner brackets, turning assembly components, wheels, car bodies, etc.

[0147] Other uses and advantages of topology optimization will become apparent from the following description.

[0148] The load handling apparatus and related methods disclosed herein are intended for operation in a storage and retrieval system such as those described above in connection with the prior art. The storage and retrieval system may be modified to accommodate the load handling apparatus described herein. Furthermore, the load handling apparatus operating on the grid of the storage and retrieval system is intended to operate in conjunction with or simultaneously with other apparatus operating on the grid. The apparatus operating on the grid may all be of the same type, or more than one type of apparatus may be operating simultaneously on the grid.

[0149] The load handling apparatus described herein are intended to be lightweight and relatively inexpensive to manufacture. Additionally, as will become apparent from the following description, the load handling apparatus described herein are substantially modular, with components that can be easily assembled and replaced, making them easy and / or inexpensive to maintain. Where possible, components are made from recyclable or environmentally friendly materials.

[0150] The load handling apparatus 100 may include a skeleton 102, body, or frame, which supports, carries, or houses other components of the load handling apparatus, such as batteries and associated electronics, controls and communication devices, motors for driving the wheels, motors for driving the lifting assembly, and other sensors and systems. The skeleton 102 includes recesses sized to accommodate the containers or accumulation bins when they are lifted by the lifting assembly. The skeleton structure of the load handling apparatus helps ensure that the components are easily accessible.

[0151] As described above with reference to the other load handling devices, each load handling device is arranged to run in the x and y directions on rails 22 of the framework 14 above the stack 12 of containers or accumulation storage bins.

[0152] 5-7 and 20, each load-handling apparatus is fitted with two sets of wheels 116, 118 that run on rails mounted on top of a storage system frame of the type described above. At least one wheel 116, 118 of each set is driven to enable movement of the vehicle 102 in the x and y directions along the rails, respectively. The wheels 116, 118 are arranged around the periphery of the load-handling apparatus skeleton 102. As described below, one set of wheels 116 can be moved vertically to lift one set of wheels 116 off its respective rail and leave the other set of wheels in contact with the rail, thereby enabling the load-handling apparatus to turn. In some cases, both sets of wheels 116, 118 can be in contact with their respective rails simultaneously.

[0153] The components that displace the or each set of wheels relative to one another in the vertical or z direction, and the skeleton 102 of the load handling apparatus, are located within the body or skeleton 102 of the load handling apparatus.

[0154] 5-7, the first set of wheels 116 and the second set of wheels 118 can be raised off the rails or lowered onto the rails by a diverting assembly that includes compliant mechanism(s) 110 or linkage sets located on opposite sides of the load handling apparatus skeleton 102.

[0155] The turning compliant mechanism 110 is deformable in a first and second direction, respectively. Figure 6 illustrates the compliant mechanism 110 in three positions and, below, the position of the wheels 116, 118 relative to the vehicle frame 102 and rails in each of these positions. Figure 7 is a perspective view of the load handling apparatus showing the position of the compliant mechanism 110 and wheels in a position similar to that shown in Figure 6.

[0156] When there is no input force, the compliant mechanism 110 is at rest or in a neutral position, i.e., it is not elastically deforming and both sets of wheels 116, 118 are horizontal and resting on a surface. In this arrangement, the load handling apparatus cannot move in either the x or y direction and the load handling apparatus is at rest (FIGS. 6a and 7a). The elastic deformation of the compliant mechanism 110 is linked to an arm that holds each of the wheels and is movable in the vertical (or z) direction to raise and lower the wheels.

[0157] When a first input force F1 is applied, the body of compliant mechanism 110 deforms in a first direction. The displacement of the mechanism body is translated vertically, lowering the first set of wheels 116 and raising the second set of wheels 118. As shown in Figures 6c and 7c, the wheels of the first set of wheels 116 move downward to engage the rails and support the vehicle, and the wheels of the second set of wheels 118 move upward to move away from the rails. Thus, the vehicle 100 can be driven in the x-direction.

[0158] When a second input force F2 is applied in a direction opposite to the first input force, the compliant mechanism 110 body deforms in a second direction. The displacement of the mechanism body translates to vertical movement to raise the first set of wheels 116 and lower the second set of wheels 118, so that the load handling apparatus can be supported by the second set of wheels 118 and driven in the y direction (FIGS. 6b and 7b).

[0159] The compliant mechanism 110 is connected to these sets of wheels 116, 118 via transfer linkage. Thus, in this manner, the compliant mechanism 110 provides a means for changing the direction of travel of the load handling apparatus 100.

[0160] 6a-6c will be understood to comprise a series of posts or trunk sections attached to rails or braces. The posts or trunk sections 111 are attached to the rails or braces 112 via relatively narrow sections that preferentially flex when a horizontal force is applied to the rails or braces. The narrow sections may therefore be considered to be hinges 113.

[0161] Considering the geometry of the turning compliant mechanism 110 in more detail, and referring by way of example to FIGS. 8a-8c, the compliant mechanism 110 comprises several posts or trunk sections 111 attached to upper braces 112a and lower braces 112b through a series of upper and lower hinges. FIG. 8a illustrates a compliant mechanism 110 in which each of the trunks is attached by a branch-type flexure hinge 120. FIG. 8b illustrates a compliant mechanism 110 in which each of the trunks is attached by a zigzag spring-type flexure hinge 121. The zigzag spring-hinge trunks 111 additionally have tethers 123 to keep the trunks 111 in place between the upper and lower braces 112.

[0162] 9, flexure hinges can be of two types: a branch type, in which the trunk section 111 is attached at each end to the brace 112 by a thin, flexible branch 120 that extends from points on either side of the trunk 111 a short distance from each end of the trunk 111 to the brace 112; and a spring type, in which the trunk section 111 is attached at each end to the brace 112 by a thin, flexible zigzag spring 121 that extends from the end of the trunk 111 to the brace 112. To reduce the overall weight of the compliant mechanism 110, some material is removed from each of the trunk sections 111 to create a truss structure.

[0163] It will be understood that the examples provided herein are only a few of the ways to achieve the desired characteristics of the compliant mechanism 110. Other arrangements are anticipated and can be determined using machine learning or AI techniques to meet the requirements. Additionally, machine learning can be used to optimize the topology of the design to reduce the weight of the turning compliant mechanism 110.

[0164] It will be appreciated that when the compliant mechanism 110 is attached to or supported by the load handling apparatus skeleton 102, the lower brace 112b remains in a fixed position between the pair of wheels 116 or 118. On the other hand, when a force is applied to the upper brace 112a, the elastic deformation of the compliant mechanism causes the upper brace 112a to be horizontally displaced relative to the lower brace 112b. Thus, the upper brace 112a may be described or referred to as a traveler 112a.

[0165] In the following text, the x and y directions of the diverting assembly are referred to with respect to whether the first set of wheels 116 or the second set of wheels 118 are engaged with the tracks to enable travel in the x or y direction. It will be understood that the x and y directions relative to the load handling apparatus 100 depend on which plane is being referenced. The direction in which force F1 or force F2 is applied, i.e., the direction in which the resulting elastic deformation occurs, will be the same, either positive or negative.

[0166] When the compliant mechanism 110 is deformed in a first direction, i.e., the x-direction (FIG. 9a), the spring-type flexure hinges 121 are compressed and the ends of the trunks 111 engage the upper and lower braces 112 through the compressed springs 121, while the branch-type flexure hinges 120 are in a relatively extended position away from their respective trunks 111. In this way, the load between the upper and lower braces 112 is supported by the spring-type trunks 111. The engagement of the trunk portions 111 with the upper and lower braces 112 means that the maximum displacement of the upper brace 112a (traveler) relative to the fixed lower brace 112b in the first direction, i.e., the x-direction, is limited.

[0167] When the compliant mechanism 110 is deformed in a second direction, i.e., the y-direction (FIG. 9b), the branch-type flexure hinges 120 bend and become relatively parallel to the trunk 111, and the ends of the trunk 111 bearing the branch-type flexure hinges 120 engage the upper and lower braces 112, while the spring-type hinges 121 become relatively elongated and bend out of alignment with their respective trunk 111. In this way, the load between the upper and lower braces 112 is supported by the branch-type trunk 111. The engagement of the trunk portion 111 with the upper and lower braces 112 means that the maximum displacement of the upper brace (traveler) 112a relative to the fixed lower brace 112b in the second direction, i.e., the y-direction, is limited.

[0168] The position on the load handling apparatus 100 of the upper brace or traveler 112a relative to the lower brace 112b can be seen in FIG.

[0169] 9, the compliant mechanism 110 is stable or at rest in both the x and y drive directions at the limits of its allowable displacement. Also, the compliant mechanism 110 is stable when no deforming forces are applied, the compliant mechanism 110 is in a rest or neutral configuration, and substantially no elastic energy is stored. Additionally, in the stable x and y drive directions, normal loads can be carried through the trunk or column 111 of the compliant mechanism 110.

[0170] It will be appreciated that the compliant mechanism may be replaced by a fixed pin pivot point rigid linkage mechanism with a trunk or post member to support the load and have the same behavior as the compliant mechanism described above. Thus, a compliant mechanism of the type described above may be considered a type of linkage set. Advantageously, rather than the normal load being transmitted through a link joint at the pivot point, the load is carried by the linkage member.

[0171] It will be appreciated that the diverter mechanism may comprise a fixed pin pivot point linkage mechanism and / or a combination of one or more types of compliant mechanisms. Figures 30-33 show an example of a rigid linkage set 300 for use in engaging the first and second sets of wheels of a load handling apparatus as part of a diverter assembly, having similar functional behavior as the compliant mechanism 110 described above.

[0172] Linkage set 300 comprises a series of pivotally connected two-piece linkages (FIGS. 30 and 32). Considering a single two-piece linkage, at one end, primary linkage member (trunk portion) 311 is pivotally attached to traveler or upper brace 312a at knee joint 316, and at the opposite end, hingedly attached to secondary linkage member (branch portion) 313 at ankle joint 314. The opposite end of secondary linkage 313 is pivotally attached to fixed brace or lower brace 312b at toe hinge 315. Thus, each single two-piece linkage extends between traveler 312a and fixed brace 212b. To create linkage set 300, a series of similar two-piece linkages are positioned in parallel between traveler brace 312a and fixed brace 312b, as shown in FIGS. 30 and 32, to make up linkage set 300.

[0173] Rotational or angular movement of knee joint 216, ankle joint 314, and toe joint 315 is limited as described below. At ankle joint 314, primary linkage 311 has a single knuckle that is interleaved between two knuckles of secondary linkage 313. Figures 31a-31d show exploded views of the single two-piece linkage, where Figures 31a and 31b show primary linkage 311 and Figures 31c and 31d show secondary linkage 313.

[0174] As shown in Figure 31c, the secondary linkage 313 has steps 318, 321 in the zx plane face between the ankle joint 314 and the toe hinge 315. The steps 318, 321 have an inflection point between the first section 318 and the second section 321. When the primary linkage 311 is attached to the secondary linkage 313 at the pivot 314, the knuckle face 317 of the primary linkage 311 meets the step faces 318, 321 and can rotate between the first section 318 and the second section 321 of the step surface.

[0175] Similarly, the movement of the two-part linkage is limited when the lower surface of primary linkage 319 contacts the upper surface of secondary linkage 320 .

[0176] The movement of the two-piece linkage when positioned between traveler 312a and fixed brace 312b as linkage set 300 will now be described with reference to Figures 33a-33c.

[0177] Figure 33a shows the linkage set in a neutral or parked position, where the first set of wheels 116 and the second set of wheels 118 are engaged with the tracks (shown in the thumbnail) and the load handling apparatus 100 cannot travel in either the x or y direction. In this position, no force F is applied to the traveler 312a and the lower surface 319 of the primary linkage 311 rests on the upper surface 320 of the secondary linkage 313.

[0178] In FIG. 33b, a positive force F (i.e., from left to right as illustrated) is applied to traveler 312a. Applying positive force F causes primary linkage 311 to rotate clockwise about knee joint 316 and counterclockwise about ankle joint 314. Rotation about ankle joint 314 is limited by face 317 contacting surface 318. By moving traveler 312a further to the right, secondary linkage 313 lifts away from fixed brace 312b by rotating clockwise about toe hinge 315. Thus, traveler 312a is horizontally displaced in a positive direction relative to fixed brace 312b. The positive displacement of traveler 312a raises first set of wheels 116 and lowers second set of wheels 118 into engagement with the tracks (illustrated in the thumbnail), allowing load handling apparatus 100 to travel in the y direction.

[0179] In Figure 33c, a negative force F (i.e., from right to left as illustrated) is applied to the traveler 312a. Applying the negative force F causes the primary linkage 311 to rotate counterclockwise about the knee joint 316 and clockwise about the ankle joint 314. Rotation about the ankle joint 314 is limited by face 317 contacting surface 321, and the heel of the two-part linkage is forced into the fixed brace 312b. Thus, the traveler 312a is horizontally displaced in a negative direction relative to the fixed brace 312b. The negative displacement of the traveler 312a lowers the first set of wheels 116 into engagement with the tracks and raises the second set of wheels 118 (illustrated in the thumbnail), allowing the load handling apparatus 100 to travel in the x-direction.

[0180] It will be appreciated that between the x-travel position and the y-travel position the linkage set moves through a neutral or park position.

[0181] The output of the compliant mechanism or linkage set 110, 300 is transmitted to the wheels 116, 118 via a chassis 330, further described below in connection with Figures 34 and 35, which converts horizontal movement of the compliant mechanism into vertical movement of the wheels.

[0182] In some arrangements, the upper brace or traveler 112a may be attached via slide bearings to a rod arrangement that extends along the face of the load handling apparatus 100 between each of the horizontal edges of the load handling apparatus 100. The rod arrangement, in turn, may be attached to corner pieces at first and second ends, which pivot about their respective edges. The corner pieces may extend around the corners to a second face perpendicular to the first face, such that the linkage extends around the entire load handling apparatus 100. In use, pivoting of the corner pieces may translate into vertical or z-direction movement relative to the wheel mounts. A clockwise pivot may move the wheel mounts on the face upward, raising the wheels on the face and lowering the wheels on the face perpendicular to the first face, or vice versa.

[0183] The linkage between the compliant mechanism 110, 300 and the corner piece is a distributed compliant mechanism and may be considered suitable for AI design. Furthermore, the corner piece is an example of a part of a device that is suitable for topology optimization.

[0184] 5 and 7, a first pair of compliant mechanisms 110, 300 are disposed on opposing faces within the load handling apparatus skeleton 102 to control the position of a first set of wheels 116, and a second pair of compliant mechanisms 110 are disposed on orthogonal opposing faces within the load handling apparatus skeleton 102 to control the position of a second set of wheels 118. Thus, each face of the load handling apparatus is provided with a compliant mechanism 110. The pairs of compliant mechanisms 110, 300 are coupled via a transmission belt 108 that substantially circumnavigates the load handling apparatus skeleton 102 and is mechanically coupled to the upper braces or travelers 112a, 312a of the compliant mechanisms 110, 300. This ensures that the wheel sets 116, 118 can be moved in unison, for example, via corner pieces, to engage the wheel sets in the x and / or y directions with the rails of the storage system grid. In this manner, the diverting assembly can be operated by a single motor. In some examples of the load handling apparatus 100, the diverting motor can be located in or near a vertical corner piece arrangement to avoid occupying space within the framework and for accessibility. In some examples of the diverting assembly, the transmission belt 108 can pass over one or more idler pulleys to monitor its rotational speed as it moves between its x- and y-engaged positions to provide immediate detection of a belt 108 failure. In the event of a failure of the belt 108 or another part of the diverting assembly, this information can be fed back to and used by the centralized control facility to prevent robot collisions.

[0185] The linkage members may be made, for example, from carbon fiber rods. The transmission belt 108 may be, for example, a toothed polyurethane tape reinforced with glass, steel, or carbon fiber.

[0186] Figures 34 and 35 show in more detail how the arrangement of diverting linkage sets 100, 300 is attached to the wheels 116, 118 and located on each side of the load handling apparatus 100. Figure 34 shows a side view of the wheel mounting or wheel chassis and linkage 330, while Figure 35 shows an isometric view showing the wheel chassis and linkage 330 on each side of the load handling apparatus. It will be appreciated that Figures 34 and 35 show the wheel chassis and linkage or wheel mounting 330 in more detail compared to Figure 14.

[0187] A linkage set 300 is located on each side of the load handling apparatus 100 and is connected to the wheels 116, 118 of the load handling apparatus 100 via a chassis 330. As described above, the upper brace or traveler 312a of the diverting linkage set is fixed vertically (z-direction), while the lower brace 312b can move vertically in response to horizontal movement of the upper brace 312a. The lower brace 312b is fixed to the wheel chassis 300, thus enabling the diverting linkage set 300 to raise and lower the respective wheels 116, 118. Vertical movement of the chassis 330 is guided by skeletal members 331 located at the corners of the load handling apparatus.

[0188] It will be appreciated that the linkage sets 300 may be reversed or arranged in a mirror image as compared to the illustrations of Figures 30-33. As seen in Figure 35, the linkage set 300 for the x-direction wheels 116 is a mirror image as compared to the linkage set 300 for the y-direction wheels 118.

[0189] Thus, when the wheels 116, 118 are driven, the linkage set 300 is in the position shown in Figure 33c with the primary linkage 311 substantially vertical. Advantageously, in this position the weight of the linkage set 300 and the load handling apparatus carried through the linkage set 300 is conducted through the linkage members 311, 313 rather than through the pivots 314, 315, 316.

[0190] As will be apparent, as the linkage set 300 moves between the wheels up, parked, and wheels down positions, the distance between the wheels 116, 118 and the body 102 of the load handling apparatus changes. The change in wheel height may place additional tension on the drive belt 271, or the change in height may cause the drive belt 271 to become slack (drive belt arrangements are described in more detail below). The geometry of the two-part linkage may be selected to advantageously limit or avoid additional tension on the drive belt 271.

[0191] Figures 36a and 36b compare the drive belt tension caused by the turning action of a single-member linkage (Figure 36a) with a two-piece linkage (Figure 36b) having a similar geometry to that described above. In the graphs, the force on the drive belt is shown on the x-axis, while the wheel height is shown on the y-axis. For both graphs, a plot for the x-direction and a plot for the y-direction are drawn using the single-member linkage. At + / -1, one set of wheels 116, 118 are elevated while the other set of wheels 118, 116 are engaged with the tracks, respectively.

[0192] In FIG. 36a, where the plot intersects on the zero line, both sets of wheels are engaged with the track, i.e., in the parked position. As can be seen, the plot follows a sinusoidal path, descending below the zero line. The difference between the zero line and the minimum value represents the maximum applied force to the drive belt during the turning operation. The value of the maximum applied force depends on the length of the single-piece linkage or compliant mechanism. By employing a two-piece linkage, as illustrated in FIG. 36b, the plot follows a complex compound path. The path depends on the relative lengths between the first linkage member 311 and the second linkage member 313 and on the rotation limits on the pivot points 314 and 315. The path follows a first path 1 while the first pivot point is rotating; once the rotation limit is reached, the path is inflected and follows a second path 2 following the rotation about the second pivot point. In the parked position, the wheels are slightly elevated. The path then continues to merge into a sinusoidal path, tracing the motion of a single member. This compound path can be arranged to avoid dipping below the zero line during the turning function, and therefore avoid placing additional tension on the drive belt.

[0193] It will be appreciated that additional motors may be used for each turn compliant mechanism 110, 300, or for groups of turn compliant mechanisms. Such an arrangement may provide redundancy for the turn assemblies, additional torque to operate the turn assemblies, or avoid the need for a transmission belt 108 that travels completely around the load handling apparatus backbone 102.

[0194] It will be appreciated that if more than one motor is used, they may be operated independently, however, for efficient turning, the motors are coordinated to operate synchronously to raise and lower each set of wheels simultaneously.

[0195] It will be appreciated that variations in the arrangement of the diverting assembly may result in similar properties and are within the intended scope of the present invention.

[0196] The compliant mechanism(s) 110, 300 may be operated by a motor or solenoid or worm gear or lead screw mechanism or any suitable means housed within the device backbone 102 to apply input forces F1 and F2 in first and second directions, respectively.

[0197] As mentioned above, each load handling apparatus is fitted with two sets of wheels 116, 118 that run on rails mounted on top of the frame of a storage system of the type described above. Either the first set of wheels 116 or the second set of wheels 118 is driven to enable movement of the vehicle 102 along the rails in the x and y directions, respectively. The wheels 116, 118 are arranged around the periphery of the skeleton 102 of the load handling apparatus.

[0198] 10-13 illustrate an example wheel 150 for use in the first wheel set 116 and the second wheel set 118 on a load handling apparatus as described herein.

[0199] Wheel 150 has a sandwich-like layered construction, with each layer imparting different optimized properties to the wheel. Between the hub and rim, the spokes are arranged in a web 155.

[0200] The central, inner, or first type layer 151 (FIG. 11) has several radial spokes 156 that connect the hub to the rim. The design of the central layer spokes is to optimize compressive strength. The rim has a plurality of gear teeth 157 for cooperation with the drive belt. The first type layer 151 may be made from a rigid, load-bearing material such as epoxy. Thus, the first type layer 151 is part of the drive train.

[0201] Outer layers or second type layers 152 (FIG. 12) are fitted to each side of the central layer 151 and have a slightly larger diameter than the central layer 151 to create channels 153 therebetween, with the gear teeth 157 of the central layer 151 at the bottom of the channels 153. Thus, when the drive belt is received within the channels 153, it tends to remain in position engaging the gear teeth of the central layer 151.

[0202] The spokes 159 of the outer layer 152 are curved and arranged to form a mesh 158. A first set of spokes 159a are curved in a clockwise direction, and a second set of spokes 159b are curved in a counterclockwise direction, overlapping the first set of spokes. The two sets of spokes are joined or fused where they intersect. The inner layer spoke arrangement is for optimizing torsional stiffness. The outer layer spoke arrangement is for maximizing torsional stiffness while also allowing radial deflection. In some examples, the spoke arrangements of the inner and outer layers can be the same shape. Generally, the inner layer will be made from a stiffer material than the outer layer and have a thicker shell or rim to reduce radial deflection.

[0203] FIG. 13 shows a portion of spokes 159 of a wheel outer layer 152 of the type shown in FIG. 12. Additionally, FIG. 13 illustrates the direction of forces in a wheel in use. In FIG. 13a, for simplicity, a single clockwise curved spoke 159a and a single counterclockwise curved spoke 159b are shown extending from the hub 160 to the rim 161. When a rotational force is applied to the wheel, as indicated by the arrows around the circumference of the wheel, the force is transmitted along the spokes 159 in the direction shown. In FIG. 13b, for simplicity, a radial portion of a spoke mesh 158 is shown, comprising segments 162 between the nodes of several clockwise curved spokes 159a and a corresponding number of counterclockwise curved spokes 159b. When a compressive force is applied to the second type layer 152, an opposing rotational force is transmitted at each node of the mesh section, as indicated by the downward arrows at the bottom of the wheel.

[0204] The rim 161 of the outer layer 152 is deeper relative to the rim of the center or inner layer 151. The outer surface of the rim is angled relative to the plane of the wheel, with each side forming half of a "V," providing a relatively smooth surface. This helps ensure that the wheel stays within the tracks or rails of the storage system grid and runs smoothly between grid spaces. The outer layer 152 may be made from a nylon material to allow the outer layer 152 to flex and for a relatively low coefficient of friction, allowing the rim to slide or roll smoothly along the tracks or rails. The flexibility of the outer layer 152 provides some shock absorption and suspension for the wheel 150. The spoke mesh 158 may be considered a compliant mechanism. Thus, the outer layer may be known as a spring section.

[0205] The periphery of the outer layer includes a groove 163 for receiving an O-ring 164. The O-ring 164 may be made of a relatively compliant material, such as rubber, to provide traction or grip between the wheel 150 and the track and to absorb bumps in the track between the grid spaces. The O-ring 164 may be thought of as a tire for the wheel 150. The flexibility of the outer layer 152 may reduce wear on the O-ring.

[0206] In addition to their different geometries, the center and outer layers may impart different properties through the use of different materials. For example, the curved spokes may be made from a relatively more flexible material compared to the radial spokes to provide some suspension to the wheel in addition to any suspension provided by the O-rings. Furthermore, the rim and hub may be made from a relatively stiff material to help maintain the wheel shape.

[0207] A hub 160 fits through each layer of wheels and has a bearing in the center for rotatably mounting the wheels 150 to an axle on the load handling apparatus skeleton 102. This allows the wheels 150 to be easily replaced if they become worn or damaged during use.

[0208] The pair of wheels 150 may be coupled to the skeleton 102 by a wheel chassis 165, as illustrated in Figure 14. The chassis 165 extends between the first and second wheels 150 and includes first and second axle mounting portions 166, which help maintain the relative position between the first and second wheels 150. In this way, the entire chassis arrangement 165 may move in the vertical z-direction as the turning assembly is operated. Alternatively, the first and second wheels 150 may move relative to the chassis arrangement 165, for example along slots in the chassis, whereby the chassis is fixed relative to the skeleton body 102 of the load handling apparatus.

[0209] The sets of wheels 116, 118 further comprise part of a drive assembly for the load handling apparatus to enable the load handling apparatus to move on the grid. A drive belt assembly 170 is provided for each set of wheels 116, 118.

[0210] The drive belt assembly 170 comprises a drive belt 171 pulley gear arrangement for engaging the toothed edges of a pair of wheels 116, 118 on one side of the load handling apparatus 100, as illustrated in Figure 15. The toothed drive belt 171 engages both of the wheels 150. The drive belt 171 is guided by a driven wheel 172 mounted on the load handling apparatus skeleton 102 and by two tensioning wheel arrangements 173. The tensioning wheel arrangements 173 are movably mounted to the load handling apparatus skeleton 102 by springs (not shown) and are intended to keep the drive belt 171 taut and maintain engagement between the drive belt 171 and the wheels 150. A drive wheel 174 is provided and mounted to the load handling apparatus skeleton 102.

[0211] The drive wheel is driven by a pulley and gear arrangement 175 linked to the shaft of a motor (not shown in FIG. 15).

[0212] The load handling apparatus 100 is provided with a drive assembly 170 for each pair of wheels 150. Each pair of wheels includes one set of wheels 116, 118. The drive wheels 174 on each side of the load handling apparatus may share a common motor shaft so that each pair of wheels 150 is driven simultaneously and at the same speed. As a result, only a single motor is required to drive the load handling apparatus 100 forward and reverse in the first x-direction, and only a single motor is required to drive the load handling apparatus 100 forward and reverse in the second y-direction. This arrangement may advantageously reduce costs in terms of space within the load handling apparatus and the number of required parts. The first set of wheels 116 and the second set of wheels 118 may be selectively driven under the control of the load handling apparatus.

[0213] 15, it will be appreciated that as the set of wheels 116, 118 moves out of position for engagement with the grid track, the drive belt may become slack because the distance between the top of the drive belt assembly 170 and the wheels changes as the wheels are lowered and raised. Therefore, depending on the diverting assembly selected, additional tensioning mechanisms may be required. For example, an idler pulley on a mechanical linkage connected to the diverting assembly may be used to keep the notional drive belt length constant throughout the diverting assembly's range of motion.

[0214] An alternative drive belt assembly 270 is illustrated in Figures 21-24. Similar to drive belt assembly 170, a drive belt assembly 270 is provided for each set of wheels 116, 118 on the face of the load handling apparatus 100. The upper portion of the drive belt assembly 270 is attached to the upper portion of the load handling apparatus backbone 102. The lower portion of the drive belt assembly 270 extends around a wheel 116 or 118 attached to the lower portion of the chassis 165 or load handling apparatus backbone 102.

[0215] Similar to the arrangement illustrated in Figure 15, the drive belt assembly 270 comprises a drive belt 271 pulley gear arrangement for engaging the toothed edges of a pair of wheels 116 or 118 on one side of the load handling apparatus 100. The toothed drive belt 271 engages both wheels 116 or 118, which are typically of the wheel type 150 described above. The drive belt 271 is guided by a driven wheel 272 mounted on the top of the load handling apparatus backbone 102. The drive belt assembly 270 further comprises tensioning means, which may also be referred to as pretensioning means.

[0216] It will be appreciated that when the diverter mechanism 110 raises the wheels 116 or 118, the belt path length is shortened because the vertical distance between the top of the equipment framework to which the diverter mechanism 110 is attached and the wheels 116 or 118 is reduced by the vertical movement of the wheels 116 or 118 between the wheels-down and wheels-up positions. If the drive belt were not otherwise tensioned or pre-tensioned, it would become slack and risk losing contact with the drive wheels 175, 275 and driven wheels 116 or 118. Such loss of contact could render the load handling equipment's drive belt assembly 170, 270 unusable. Furthermore, a slack drive belt 171, 271 could catch on equipment operating on adjacent tracks.

[0217] The upper part of the tensioning means is attached to the upper part of the device skeleton 102 to which the redirection mechanism 110 is also attached, and is coupled to the redirection mechanism 110.

[0218] A first arm 273 of the tensioning means extends from one end of the redirection mechanism 110, has an elbow at its midpoint, and has a guide wheel at its distal end. The first arm 273 can rotate about a pivot point at the elbow midpoint between positions. A second arm 274 is rotatably attached to the device frame 102 at a pivot point located near the redirection mechanism 110 at the opposite end from the first arm 273. The second arm 274 has a guide wheel at its distal end.

[0219] Further parts of the tensioning means are mounted to the bottom of the chassis 165 or skeleton 102. A fixedly mounted driven wheel 276 guides the drive belt 271 from the wheel 116 and around a pulley 277. The pulley 277 can be moved in the direction shown by the arrow to adjust and / or measure the path length of the drive belt 271. It will be understood that additional driven wheels 276 can be used.

[0220] Typically, a fixed belt length is used and the belt path length is adjusted using additional pulleys to fine-tune the path length to substantially match the fixed belt length. It will be understood that the belt may stretch under tension and this is factored into the geometric design of the drive belt assembly.

[0221] As seen in FIG. 22 , which shows a perspective view of the tensioning means, the drive belt is threaded through first tensioning arm 273 and second tensioning arm 274. The rotating portions of first arm 273 and second arm 274 are biased to a wheels-up position, as shown in FIG. 23 c. The arms 273, 274 may be biased by any suitable biasing means, such as a simple spring arrangement. In the neutral or parked position, the diverting mechanism 110 is positioned substantially in the center of its range of motion. In the neutral position, the distal end of arm 273 is angled slightly away from the axis of the end fixed to the diverting mechanism. The second arm 274 is at rest and angled slightly downward from the top of the skeletal body 102. Drive belt 271 is positioned to travel over a guide wheel at the distal end of first arm 273 with reduced directional force from the guide wheel, and drive belt 271 is positioned to travel over a guide wheel at the distal end of second arm 274 with reduced directional force from the guide wheel. In the neutral position, drive belt 271 is engaged with drive wheel 275 and driven wheel 116 but is neither relatively taut nor relatively slack, i.e., drive belt 271 is not pretensioned.

[0222] As shown in Figures 23c and 24a for the y-direction wheel 118 and in Figure 24c for the x-direction wheel 116, when the wheels 116, 118 are in a lowered or down position controlled by the diverting mechanism 110 to engage a surface or track, the diverting mechanism 110 is moved to the opposite side to be positioned closer to the second arm 274. In this position, the distal end of the first arm 273 is rotated at the elbow in the opposite direction about the pivot point compared to the neutral position. The drive belt 271 is arranged to move on a guide wheel at the distal end of the first arm 273, which pulls against and exerts a force on the drive belt 271. The drive belt 271 is arranged to move on a guide wheel at the distal end of the second arm 274 with the directional force from the guide wheel reduced. As a result, in the engaged or wheel down position, the tensioning means applies some tension to the drive belt 271 via the first arm 273 to keep the drive belt 271 relatively taut or pre-tensioned. Advantageously, the tensioning means helps to ensure that the drive belt 271 remains engaged with the drive wheel 275 and the driven wheel 116 or 118 when the wheel 116 or 118 is in the down position for engagement with a surface or track.

[0223] When the wheels 116, 118 are in the raised position so that they are disengaged from the surface or track, as shown in Figures 23a and 24c for the y-direction wheel 118 and in Figure 24a for the x-direction wheel 116, the redirection mechanism 110 is moved to the opposite side so that it is positioned away from the second arm 274. In this position, the distal end of the first arm 273 is rotated at a larger angle in the same direction compared to the neutral position. The drive belt 271 is positioned in contact with an additional guide wheel at the midpoint elbow of the first arm 273 and a guide wheel at the distal end of the first arm 273. The belt arrangement on the first arm 273 in the wheel-raised position increases the length of the path followed by the drive belt 271 on the first side of the tensioning means. Because drive belt 271 remains substantially the same length regardless of the position of the tensioning means, and as a result of lengthening the belt path on the first side, drive belt 271 contacts and pulls against the distal end of second arm 274 to shorten the belt path by an equal amount on the second side of the tensioning means, causing the second arm to rotate into a more vertically aligned position. Advantageously, the tensioning means compensates for the reduction in vertical distance between the top of skeleton 102 and wheel chassis 165, keeping the belt taut enough to prevent it from becoming slack enough to disengage from drive wheel 275 or from disengaging from driven wheels 116 or 118.

[0224] Advantageously, the tensioning means is directly linked to the diverting mechanism 110 so that the tensioning means operates in unison with the diverting mechanism 110. Therefore, no additional control or separate actuation function is required to tension the drive belt 271 when the diverting mechanism 110 raises and lowers the sets of wheels 116 and 118, respectively.

[0225] Considering the tensioning means used during the transition from the wheel 118 up state to the wheel 118 down state (i.e., from FIG. 24c to FIG. 24b to FIG. 24a), first the elbow joint is bent downward and the belt 271 is pulled inward on a first side and a second side by the biasing means, which exert a relatively small force just enough to prevent the belt 271 from slackening and ensure that the teeth of the belt mesh with the various pulleys (FIG. 24c).

[0226] During the transition, the load is transferred from the first set of wheels 116 to the second set of wheels 118. Halfway through the transition, the turning motor is working hardest, or at its peak load, to perform the wheel change required for the turning operation. During this time, the belt 271 is relatively slack. The tensioning means applies additional load to the turning motor to rotate the elbow joint of the first arm 273 against the biasing means. As the second set of wheels 118 begins to carry the load of the device, the elbow is pulled straight, which substantially aligns the shaft distal end of the arm 273 with the fixed end of the first arm 273, and the guide pulley at the distal end directly pulls on the belt 271, creating a relatively large pretension on the belt (FIG. 24b).

[0227] Finally, when the load is transferred to the second set of wheels 118, the elbows are pulled by the biasing means into a rotated position to prevent the belt 271 from becoming slack (Figure 24a).

[0228] It will be appreciated that the placement of the elbow on the first arm 273 allows the tensioning means to be adjusted to control the point at which maximum force is required for the belt 271 pretensioning means.

[0229] Separating the force requirements of the diverting mechanism 110 from the force requirements of the tensioning means advantageously allows the size of the motor required to be minimized.

[0230] It will be apparent that the tensioning means may alternatively be adjusted and biased to a wheels down or parked position rather than a wheels up position. It will be understood that alternative tensioning means may be used.

[0231] The tensioning means is intended to keep the drive belt 271 taut and maintain engagement between the drive belt 271 and the wheels 150, 116 when the wheels are positioned to engage or disengage from a surface and when the wheels are in a neutral position or transitioning between engaged and disengaged positions.

[0232] As is known, ideally, for a belt drive assembly to be effective, there should be six teeth in contact between the drive belt and the drive wheel. This can be ensured by including an additional wheel to provide a mega-drive assembly.

[0233] During operation of drive arrangement 270, drive belt 271 is driven by drive wheel 275. The path of drive belt 271 onto drive wheel 275 is assisted by mega drive wheel 278. Mega drive wheel 278 is positioned adjacent drive wheel 275 and guides drive belt 271 such that an increased number of teeth are engaged between drive wheel 275 and drive belt 271 compared to when the mega drive wheel is not present. Typically, when mega drive wheel 278 is used, about six or more teeth of drive belt 271 are engaged with drive wheel 275.

[0234] As is known, in gear tooth drive arrangements, backlash is the error in motion that occurs when the drive direction changes from forward to reverse or vice versa. This exists because there is always a small gap between the trailing face of a drive tooth and the leading face of the tooth behind it on the driven belt, and that gap must close before force can be transmitted in the new direction. The amount of backlash depends on the size of the gap. In an ideal drive belt / wheel gear arrangement, there would be no gap between the drive belt teeth and the wheel teeth. However, this would require perfect manufacturing and uniform dimensional characteristics throughout the system. If a drive belt is used, additional backlash can be introduced by belt stretching. At least a portion of the backlash that occurs during forward and reverse direction changes can be compensated for by the wheel spoke design. Therefore, it will be understood that suitable materials should be selected. For example, the drive belt 171 can be made from polyurethane, rubber reinforced with steel strands, rubber reinforced with fiber, etc.

[0235] FIG. 25 illustrates a top view of a load handling apparatus showing a drive motor arrangement suitable for driving the drive assembly 170 or 270. A first drive motor 290 is coupled to a first drive shaft 292 via a first gear arrangement 291. This drive shaft extends across the width of the load handling apparatus in the y direction to drive the assembly 170 or 270 to drive the wheel 116 in the x direction. The motor 290 is located toward one end of the drive shaft 292. As a result, the length of the drive shaft 292 to a first side is shorter than the length of the drive shaft 292 to the opposite side. As is known, torsional stiffness decreases with length. Therefore, assuming both sides of the drive shaft 292 are made from the same material, the drive shaft on the shorter length has a proportionally thinner diameter compared to the drive shaft on the longer length to ensure that the torsional stiffness between each side is matched. In an alternative arrangement, the two sides of the drive shaft may be made from different materials to match the torsional stiffness. For example, the shorter length may be made from aluminum rod, while the longer length may be made from carbon fiber rod having a similar diameter. In this way, opposite sides of the load handling apparatus are driven by the same motor 290 and are subjected to the same torsion.

[0236] Similarly, a vertically disposed second drive motor 290' is coupled via a second gear arrangement 291' to a second drive shaft 292' that extends across the width of the load handling apparatus in the x direction to drive assembly 170 or 270 for driving wheel 116 in the y direction.

[0237] Advantageously, the drive motor arrangement requires only two motors to drive the load handling apparatus in the forward and reverse x and y directions.

[0238] In an alternative arrangement, the drive assembly may include four drive motors, one to drive each of the drive assemblies 170 or 270 .

[0239] Advantageously, control of the load handling apparatus is simplified because there are a limited number of movements and assemblies required to maneuver the load handling apparatus, thus reducing the amount of coordination between movements. In this arrangement, each of the eight wheels 150 of the load handling apparatus is a driven wheel 150.

[0240] In larger, lightweight equipment, the corners of the load handling equipment can be multifunctional, providing room for mounting and integrating many components of the load handling equipment assembly. Drive motors can be mounted on top and / or at corners of the boat. Advantageously, this mounting location requires fewer fasteners. Advantageously, this arrangement can allow for shorter cables for power and data transmission to the actuators. Advantageously, this arrangement places many of the complex components of the load handling equipment in easily accessible locations, thus reducing maintenance time and labor costs.

[0241] 26-29 illustrate an alternative wheel design 250 for use as the first wheel set 116 and the second wheel set 118 on a load handling apparatus as described herein. The wheel 250 is intended to be suitable for use with a hub motor. As illustrated, the hub 260 has a relatively large diameter to accommodate the hub motor. As a result, the distance between the hub 260 and the rim is reduced, and the spokes 259 are confined to a relatively narrow band between the hub 260 and the rim.

[0242] The rim of the hub 260 is relatively wide and includes several attachment points 251 for securing the wheel 250 to a hub motor.

[0243] The spokes 259 are arranged to form a truss arrangement. The spokes 259 can be straight or can be curved alternating clockwise and counterclockwise. In some arrangements, the spokes 259 can be arranged as two overlapping and oppositely oriented part-spirals. The spoke arrangement is intended to maximize torsional stiffness while also allowing for radial flexure.

[0244] FIG. 27 shows a portion of a spoke 259 arrangement for a wheel outer layer 152 of the type shown in FIG. 26. Additionally, FIG. 27 illustrates the direction of forces in a wheel in use. For simplicity, similar to FIG. 13, only a small portion of the spokes 259 are shown. With reference to FIG. 27a, when a rotational force is applied to the wheel, as indicated by the arrows around the circumference of the wheel, the force is transmitted along the spokes 259 in the direction shown. With reference to FIG. 27b, when a compressive force is applied at the bottom of the wheel, as indicated by the downward arrows, opposing rotational forces are transmitted through each node where the spokes 259 join the hub rim.

[0245] The periphery of wheel 250 is provided with a series of grooves 263 for receiving a corresponding number of O-rings 264. O-rings 164 may be made of a relatively compliant material, such as rubber, to provide traction or grip between wheel 250 and the track and to absorb bumps in the track between grid spaces. O-rings 264 may be thought of as tires for wheel 250. The flexibility of wheel 250 may reduce wear on O-rings 264 during use.

[0246] Wheel 250 may be made from a single layer, or wheel 250 may have a sandwich-like layer structure, similar to wheel 150.

[0247] Considering the wheel 250 in a radial direction, as seen in Figure 26c, between the O-ring 263 tire and the outer plane of the wheel is a thin sandwich-like layer 265 that provides a gap between the body and outer edge surface of the tire or wheel 250. This gap allows the wheel 250 to deform or "squashed" into a narrower track.

[0248] Wheels 250 of the type described in connection with Figures 26 and 27 are suitable for being driven by hub motors, and therefore use a direct drive arrangement rather than the belt drive arrangements described elsewhere in this disclosure.

[0249] Figure 28 illustrates a hub motor 280 suitable for use with wheel 250, and Figure 29 illustrates hub motor 280 mounted to wheel 250. Hub motor 280 includes a motor 281, a wheel mounting portion 282, and a mounting plate 283 for mounting hub motor 280 to a vehicle.

[0250] 37-41 illustrate an alternative wheel design 350 for use as the first wheel set 116 and the second wheel set 118 on a load handling apparatus as described herein.

[0251] FIG. 37 shows an exploded view of the wheel 350, showing each of the component parts. Starting substantially from the center, the wheel 350 comprises a pulley 351. A spring section or layer 352 is attached to each face of the pulley 351, and an O-ring 364 is fitted onto the rim of the spring section 352. First and second torque-limiting or contact plates 354 are then fitted together through the central hub of the pulley 351 and the spring section 352. First and second bearings 355 are fitted onto the abutment plates 354. Finally, a front cap plate 356 is fitted onto the bearings 355 and secured to a rear cap plate (not shown) with screws or bolts 357. FIG. 38a shows a plan view of the assembled wheel 350, and FIG. 38b shows a cross-sectional view of the wheel 350 taken along line XX in FIG. 38a. As can be seen in the cross-sectional view, the channel 353 is located between the O-rings 364. As described herein, channel 353 may receive a drive belt that engages with the teeth of pulley 351 to drive wheel 350. As mentioned above, O-rings 364 engage tracks or surfaces to support the load handling device to which they are attached.

[0252] FIG. 39 shows the spring layer 352 of wheel 350 in more detail, as a plan view in FIG. 39a and a perspective view in FIG. 39b. Similar to the wheels 150, 250 described above, the spokes 359 are curved in a clockwise and counterclockwise direction to form a net or mesh for transmitting forces between the hub and the rim. The spring layer 352 will be made of a resilient material, thus allowing the spring layer 352 to bend and deform. The inner periphery of the spring layer 352 includes notches 360 that are positioned within the grooves 358 of the contact plate 354. Additionally, toward the outer edge of the spoke section, the spring layer 352 includes several regularly spaced grooves 361 for mating with similarly spaced protrusions 362 on the front and rear faces of the pulley 351, as seen in FIGS. 37 and 40. It will be appreciated that the pairing of grooves and notches or protrusions ensures that the wheel is properly aligned when assembled and can be quickly assembled by hand, for example, by a technician.

[0253] FIG. 40 shows pulley layer 351 in more detail in plan view, with the cog teeth around the circumference, protrusions 362 slightly inside the circumference and regularly spaced around the face, and notches 363 (similar to notch 360) for seating in grooves 358 in contact plate 354.

[0254] Finally, Figure 41 shows contact plate 354 in a plan view in Figure 41a and a perspective view in Figure 41b. It will be appreciated that contact plate 354 limits outward bending of spring section 352. Additionally, contact plate 354 helps prevent spokes 359 from catching on nearby objects.

[0255] 38a, it will be seen that the diameter of the contact plate 354 is slightly smaller than the diameter of the spoke section. In this manner, the rim of the wheel 350 may be able to flex inward to compensate for, for example, narrowing of the track or misalignment.

[0256] It will be appreciated that notches 360, 363 and groove 358, and groove 361 and protrusion 362, help to properly align the layers of wheel 350 and ensure that drive forces applied to the circumferential cogs of pulley 352 are transmitted to spring layer 352 to drive the load handling apparatus.

[0257] While certain wheel features are described in connection with Figures 10-15, 21-25, other features are described in connection with Figures 26-29, and additional features are described in connection with Figures 37-41, it will be understood that combinations of features from any of these figures and the associated descriptions are contemplated by the inventors. For example, a belt-driven wheel may include multiple O-ring tires, or a hub-motor-driven wheel may have a layered structure.

[0258] It will be understood that in variations of the illustrated and described wheels 150, 250, 350, the wheels may be asymmetric along the axis, i.e., the wheels may, for example, have a spring layer on only one side of the support layer or pulley layer.

[0259] As mentioned above, the load handling apparatus typically includes a space or skeletal void for receiving a container. The void is sized so that the container can fit sufficiently within the void to allow the load handling apparatus to move across the grid above the storage framework without the underside of the container getting caught on the grid or another part of the storage framework. When the load handling apparatus reaches its intended destination, the container lifting mechanism controls the lifting tapes to lower the gripper assembly and corresponding container out of the load handling apparatus and into its intended location.

[0260] The intended location may be an exit point of a stack of containers or a storage framework, or may be an entrance point of the storage framework if the load handling device moves to collect containers for storage within the storage framework.

[0261] Various lifting assemblies are described in Ocado's GB2001012.0, which is incorporated herein by reference.

[0262] 16 and 17 show representations of lifting assemblies 180, 190 of the load handling apparatus 100 for raising and lowering the container 10. The lifting assemblies 180, 190 comprise gears 182, 192 and motors 181, 191.

[0263] A common shaft 183, 193 extends through the gears 182, 192 to first and second winding drums 184, 194, around which a lifting tape 185 is wound. A first end of the lifting tape is attached to the winding drums 184, 194, and a second end of the lifting tape is attached to a gripper plate. A driven wheel 186 is used to guide the lifting tape 185 to the gripper plate attached to the end of the lifting tape 185 and / or to adjust the tension of the lifting tape 185. The gripper plate is used to latch onto a load, which can then be lifted and lowered by the lifting assemblies 180, 190.

[0264] 16, first and second lifting tapes 185 are alternately wound around drum 184. Thus, when first and second drums 184 are rotated by motor 181 to lower the gripper plate, both tapes 185 are unwound simultaneously and at the same speed. Conversely, lifting tapes 185 are wound or coiled around take-up drum 184 simultaneously and at the same speed, thereby lifting the weight or payload supported by the gripper plate.

[0265] In the assembly 190 shown in FIG. 17, the first and second lifting tapes 185 are wound around respective drums 194 at each end of a shaft 193 .

[0266] For both assemblies 180, 190, at each end of the shaft 183, 193, tape 185 is unwound from the top and bottom of the drums 184, 194 respectively to balance the forces applied to the assembly.

[0267] It will be appreciated that the diameter of drum 184 is necessarily larger than the respective drum 194 for a given length of lifting tape 185. Correspondingly, gear 182 is larger than gear 192, and the required torque generated by motor 181 is greater than the required torque generated by motor 191.

[0268] The lifting assembly 180 has the advantage that fewer parts are required. The lifting assembly 190 has the advantage that the drum 194, gear 192, and motor 191 are smaller. In either case, the lifting assembly may minimize the space required within the body of the load handling equipment 100.

[0269] The illustrated lifting arrangement has various advantages, including that space and cost within the body of the load handling equipment can be saved compared to arrangements incorporating more motors; the winding and unwinding speeds of the spools or winding drums 184, 194 do not need to be synchronized as they are all driven by the same motors 181, 191, allowing them to be wound and unwound at the same speed without additional gearing, controls, or other intervention; and only a single control unit is required to control the raising and lowering of the winding drums 184, 194.

[0270] As will be explained in more detail below, a gripper plate attached to the distal end of lifting tape 185 has one or more gripper assemblies mounted thereon for hanging onto a storage container.

[0271] The components of the lifting assembly may be directly or indirectly attached to a frame that is releasably attachable to the load handling apparatus. For example, the lifting assembly may be attached to a cross beam or rod that sits on a bracket attached to the skeleton of the load handling apparatus. The bracket may be 3D printed and optimized for weight. The lifting assembly is thus used to lift a container into the skeleton cavity of the load handling apparatus. It will be understood that the lifting assembly used in reverse may be used to lower a container from the load handling apparatus into a position in the stack below the grid.

[0272] Configuring a lifting assembly for releasable mountability to load handling apparatus advantageously means that the lifting assembly can be easily removed and replaced with another lifting assembly (e.g., if the first assembly needs to be inspected or repaired), allowing the corresponding load handling apparatus to be returned to service relatively quickly.

[0273] A communication cable reel may also be attached to the lifting assembly for transmitting control commands from the control unit to the gripper assembly. The communication cable may transmit sensor data to the control unit, for example, to ensure that the gripper plate is latched onto the container. The communication cable also raises and lowers with the gripper plate.

[0274] In an alternative arrangement, communication between the lifting assembly and the control facility may be wireless. The operation of the lifting assembly or TGA (tote gripping assembly) may be semi-autonomous.

[0275] Before the lifting assembly raises or lowers the gripper assembly and any engaged container, the redirection mechanism preferably ensures that both the first set of wheels 116 and the second set of wheels 118 of the load handling apparatus are engaged with their respective tracks. This may provide additional stability when the lifting assembly is raised and lowered, and may additionally help to ensure that any malfunction in one or more of the wheels that would cause the load handling apparatus to move along the tracks is counteracted by the other set of wheels in contact with the tracks. This may avoid damage to the storage framework if the load handling apparatus attempts to move while the gripper assembly is in the lowered configuration.

[0276] The gripper plate includes at least one gripper assembly positioned to align with a recess or hole in the top surface of the storage container so that the gripper assembly can latch onto the storage container. More commonly, the gripper plate will include two or more gripper assemblies. Typically, the gripper plate will include four gripper assemblies positioned in positions corresponding to cooperating recesses in the container.

[0277] 18-19 illustrate a self-locking gripper assembly for use in a load handling device described herein. The gripper assembly includes a flexure mechanism 210 movable between a bistable locked configuration and an unlocked configuration. The flexure mechanism 210 includes an actuator 211, two gripper arms 212 having hook ends 213, and two flexure hinge arrangements connecting the gripper arms 212 to the actuators 211. The flexure hinge arrangements include a triangular keystone-form 214, a first deformable section 215 between the actuator and the keystone-form, and a second deformable section 216 between the keystone-form and the gripper arms 212. The deformable sections 215, 216 are relatively thin sections compared to the other sections of the flexure mechanism 210. In this manner, the deformable sections preferentially bend or flex when an appropriate force is applied to the flexure mechanism 210.

[0278] Referring to Figure 18, in the locked configuration (b), the keystone shapes 214 engage or abut the respective gripper arms 212. In the locked configuration, the flex mechanism 210 is open or wide and the gripper arms are spread apart. The flex mechanism 210 can be moved to the locked configuration by applying a downward force to the actuator 211, as shown by the solid arrow in Figure 18a. The actuator 211 is in a downward position relative to the gripper arms 212.

[0279] The flexing mechanism 210 can be moved to the unlocked or released configuration by applying an upward or pulling force to the actuator 211, as shown in FIG. 18(b). When such a force is applied, the first hinge 215 and the second hinge 216 bend or flex, releasing the keystone shape 214 from engagement with the gripper arms. The first hinge 215 bends such that the keystone shape pivots downward relative to the actuator. The second hinge 216 bends such that the keystone shape 214 pivots upward relative to the gripper arms 212. Thus, the actuator 211 moves to an upward position relative to the gripper arms 212, drawing the hooked ends 213 of the gripper arms together into a narrow or closed arrangement, as shown by the solid arrows in FIG. 18(c).

[0280] An alternative arrangement of a gripper having a flexure mechanism 220 is illustrated in Figures 19a and 19b, where like features are designated with the same reference numerals. In Figure 18, a keystone shape 214 is connected to the gripper arm 212 spaced from the arm's hook end 213. The keystone shape 214 extends below a line between the first hinge 215 and the second hinge 216. In the alternative arrangement shown in Figures 19a and 19b, a keystone shape 217 is connected to the gripper arm 212 substantially at the hook end 213. The keystone shape 217 extends above a line between the first hinge 218 and the second hinge 219.

[0281] FIG. 19a shows flex mechanism 220 in a locked configuration with keystone features 217 engaged with respective gripper arms 212. In FIG. 19b, flex mechanism 220 is in a released configuration. In this case, actuator 211 is in a lowered position relative to gripper arms 212, and first hinge 218 and second hinge 219 flex in the opposite direction compared to first hinge 215 and second hinge 216 in FIG. 18. Thus, flex mechanism 220 can be moved to the locked configuration by applying an upward force to actuator 211, and flex mechanism 220 can be moved to the unlocked or released configuration by applying a downward force or pushing force to actuator 211.

[0282] As mentioned above, the gripper assembly is for latching onto the storage container 10 so that the storage container can be lifted. The gripper assembly is positioned to fit onto the storage container 10. Typically, the storage container 10 has a recess on the top surface around the edge of the container.

[0283] In use, the flex mechanism 210 is inserted into the recess in a narrow or flexed configuration. Once inserted, a downward force can be applied to the actuator 211, as shown by the solid arrow in FIG. 18a. This places the flex mechanism 210 in a locked configuration, and the flex mechanism 210 widens. In this case, it is not possible to remove the flex mechanism 210 from the recess in the container. The hook-shaped ends 213 of the gripper arms engage the underside of the top surface of the container 10. Thus, a lifting force can be applied to the gripper arms 212 to lift the container.

[0284] It will be appreciated that the flexure mechanism 220 may be used with the container 10 by applying an opposing force to the actuator 211 .

[0285] In use, as part of the load handling apparatus, gripper assembly(ies) 210, 220 are mounted on the gripper plate. Lifting tape(s) 185 are attached to the gripper arm 212. The actuator 211 may be operated by, for example, a solenoid motor or an electromagnet.

[0286] When used with a load handling apparatus, the grippers 210, 220 are used at each corner of the container 10 to latch the lifting assembly 200 to the container 10. The lifting assembly 200 is then operated to lift the container 10 into the skeletal cavity of the load handling apparatus 100 so that the container 10 can be transported by the load handling apparatus. Figure 20a illustrates the load handling apparatus without a container, and Figure 20b (and Figure 5) illustrates the load handling apparatus with a container lifted into the cavity.

[0287] It will be appreciated that the gripper assemblies 210, 220 may have more than two gripper arms and a corresponding number of flexure hinge arrangements disposed about the actuator. In some arrangements, the additional gripper arms may provide a more secure attachment to the storage container.

[0288] While this arrangement allows a single motor to raise and lower the gripper plate, it will be apparent from the foregoing that two motors may be preferable to provide some redundancy to the system and therefore provide a fault-tolerant load handling apparatus.

[0289] As mentioned above, some parts of the load handling apparatus can be easily replaced or substituted, and therefore the load handling apparatus can be considered to have a modular assembly.

[0290] The body of the load handling apparatus may be considered to be a skeletal body, skeleton, frame. Advantageously, this allows each of the modules to be more easily replaced, as there is direct or indirect access to each module. The modules may be self-contained, i.e., a single unit with several connected parts, or the modules may comprise multiple parts.

[0291] The module may comprise a turning assembly, a wheel or set of wheels, a drive assembly, a lifting assembly, a gripper assembly, a power means, a communication means, a control means, a sensing means, or a sensor pack.

[0292] This may be particularly advantageous as it may allow components within or supported by the skeleton of the load handling apparatus to be replaced more frequently, for example it may allow a rechargeable battery of the load handling apparatus to be easily removed from the skeleton and replaced with another rechargeable battery.

[0293] In order to operate autonomously, the load handling apparatus has its own power supply, which may be in the form of a rechargeable or replaceable battery.

[0294] The battery may be located within the skeleton of the load handling apparatus, for example if the skeleton comprises a hollow rod structure the battery may be inserted into the rod.

[0295] Various control and sensor arrangements are described in WO2019170805 (Ocado), which is incorporated herein by reference.

[0296] The load handling equipment is controlled by an on-board control facility.

[0297] The control facility may comprise communication means such as a transceiver unit or a transmitter and receiver unit for sending and receiving commands from a centralized control facility of the system. The load handling equipment may function substantially autonomously based on commands or tasks from the centralized control facility.

[0298] The on-board control facility may control and operate the diverting mechanism, drive assembly, and lifting assembly in accordance with commands received from the central control facility. The on-board control facility further comprises inputs from various sensors and cameras to provide feedback to the control facility regarding the status of the load handling equipment and the environment surrounding the load handling equipment.

[0299] Based on the conditions and environment surrounding the load handling apparatus, the onboard control facility operates the diverting assembly, drive assembly, and lifting assembly to perform tasks.

[0300] Accurate knowledge of the state of the load handling equipment is needed to determine the speed at which the load handling equipment can operate, when a task is completed, and when the load handling equipment is available to complete a subsequent task.

[0301] Accurate positioning of each load handling device is required to allow the load handling devices to be driven at higher speeds and / or accelerations with minimal positional errors, allowing for reduced spacing between load handling devices on the grid system and increasing the efficiency of the system.

[0302] To verify that the information received is correct, more than one type of sensor may be used to determine the state and environment of the load handling equipment. More than one sensor of the same type may be attached to the load handling equipment at different locations.

[0303] In this way, each of the sensors detects a different part of the environment that the load handling apparatus is operating in. Multiple sensors are advantageous because they provide redundancy to the apparatus in that if one sensor fails to capture appropriate information from the environment, one of the other sensors may be more successful.

[0304] Furthermore, in locations where one sensor cannot capture the environment (e.g., on a rail crossing), another sensor may be able to capture the environment more successfully. Additionally, with multiple sensors, other measurements can be made, such as determining the rotational orientation of the transport device by comparing a position measurement from one sensor with the same position measurement on a sensor mounted on an opposite surface of the transport device to determine the angle between the sensors.

[0305] Thus, while one advantage of the load handling apparatus disclosed herein is the elimination of redundancy, it will be appreciated that for operation in larger systems, some redundancy on the load handling apparatus may be desirable for other reasons, such as for sensing position on a grid.

[0306] The load handling equipment may be equipped with many different types of sensors, for example cameras, ultrasonic detectors, X-ray cameras, trundle or dead reckoning wheel arrangements, gyro scanners for reading markings provided on the grid, barcode or QR scanners, RFID readers for identifying items stored in the system.

[0307] One type of sensor that may be used with the load handling apparatus described herein is a low-cost downward-looking camera located within the framework. Such a camera may be used to detect track crossings and determine grid positions.

[0308] Sensors may be provided for evaluating communication functions within the load handling device, measuring traction between the wheels and the grid track, measuring distance traveled, measuring travel speed, determining the grid position of the load handling device on the grid, and precise positioning of the load handling device in a single grid space.

[0309] It will be understood that the load handling device may include all, one, or any combination of the features described above, and it is not essential to the invention that the service device include all of the sensors and features described.

[0310] It is envisioned that any one or more of the variations described in the preceding paragraphs may be implemented in the same embodiment of the load handling apparatus.

[0311] The invention described herein relates, by way of example, to load handling equipment for a grocery unloading system, although it will be understood that the storage systems and equipment described herein are not limited to the types of items stored and managed therein.

[0312] Furthermore, it will be appreciated that some embodiments of the present invention may be used in connection with manual handling equipment other than load handling devices.

[0313] Many variations and modifications not expressly described above are possible without departing from the scope of the invention, which is defined in the appended claims.

[0314] The following bullet points outline aspects of exemplary implementations:

[0315] 1. A load handling apparatus, wherein the at least one resiliently deformable member is a flexure hinge, and the compliant mechanism comprises a series of trunk sections attached to an upper brace and a lower brace through the flexure hinge.

[0316] 1. A load handling apparatus, wherein the flexure hinge comprises a branch portion or the flexure hinge comprises a spring portion.

[0317] 1. A load handling apparatus, wherein each compliant mechanism comprises at least one trunk section having a first type of flexure hinge and at least one trunk section having a second type of flexure hinge.

[0318] a grid framework (14) structure comprising a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to the first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights (16) to form a plurality of vertical storage locations below the grid for containers (10) to be stacked therebetween and guided vertically by the uprights through the plurality of grid spaces; at least one load handling device operating on the grid framework structure; and a centralized control utility for controlling the at least one load handling device(s).

[0319] A system, wherein at least one load handling device further comprises a communication means, and wherein the centralized control utility of the storage system comprises a communication means for communicating with the communication means on the at least one load handling device.

[0320] A system, wherein a centralized control utility remotely monitors the status of at least one load handling device.

[0321] A system in which, when malfunction and / or failure of load handling equipment is detected, the load handling equipment is commanded to move to a maintenance area or edge of a grid using non-malfunctioning and non-failed means.

[0322] A system, wherein a centralized control utility communicates with at least one load handling device operating on a grid to command the load handling device to move to a specific location on the grid.

[0323] The system further commands the load handling equipment to lift the container from the stack and move the container to another location on the grid, and / or further commands the load handling equipment to lower the container to a stack position below the grid.

[0324] A wheel, wherein the rim of the wheel includes one or more grooves for receiving an O-ring.

[0325] A wheel, wherein the rim includes three grooves for receiving three O-rings.

[0326] A wheel further comprising an additional layer that provides a gap between the depth of the body of the wheel and the outer plane, so that the wheel can be "squished" into a narrower configuration to go through narrower or misaligned sections of the track.

[0327] A wheel, wherein the wheel is a driven wheel.

[0328] A wheel, the wheel adapted to receive a hub motor.

[0329] 1. A method of pretensioning a drive belt of a drive belt assembly for a load handling apparatus, comprising the steps of:

[0330] The tensioning means, wherein the second arm is rotatably mounted.

[0331] A tensioning means, wherein the drive belt is threaded through a first tensioning arm and a second tensioning arm. The inventions described in the original claims of this application are set forth below. [1] A drive belt assembly for a load handling apparatus, said drive belt assembly comprising: A drive belt and A drive wheel; one or more driven wheels; A tensioning means, a first tensioning arm having a fixed end above an elbow and a rotatable distal end pivotally mounted at the elbow, wherein the first tensioning arm is horizontally displaceable relative to the drive wheel and the driven wheel; a second tensioning arm; and a tensioning means comprising: a drive belt assembly, wherein the drive belt is routed around the first tensioning arm and the second tensioning arm, and the first tensioning arm and the second tensioning arm are positioned to apply pressure to the drive belt to impart tension to the drive belt. [2] The drive belt assembly of [1], wherein the driven wheel is vertically movable relative to the drive wheel between a raised configuration and a lowered configuration, and the tensioning means has respective configurations corresponding to the raised and lowered configurations of the driven wheel, and the tensioning means is movable therebetween. [3] The drive belt assembly according to [1] or [2], wherein movement between the tensioning means and the driven wheel arrangement is mechanically adjusted. [4] A drive belt assembly as described in any one of [1] to [3], further comprising a direction change assembly arranged to raise or lower the driven wheel relative to the drive wheel, wherein the tensioning means of the drive belt assembly is arranged to apply pretension to the drive belt when the driven wheel is moved between a raised configuration, a lowered configuration, and a parked configuration. [5] The drive belt assembly according to [4], wherein the tensioning means is mechanically linked to the direction changing mechanism. [6] The drive belt assembly according to any one of [1] to [5], wherein the movement of the driven wheel in the vertical direction and the movement of the tensioning means are actuated by the same actuator. [7] A drive belt assembly according to any one of [1] to [6], wherein the tension applied to the drive belt varies depending on the position of the first tensioning arm and / or the second tensioning arm. [8] The drive belt assembly according to any one of [1] to [7], wherein the peak force required for changing direction occurs at a different time than the peak force required for applying tension. [9] A drive belt assembly according to any one of [1] to [8], further comprising sensing means for monitoring belt tension, and optionally further comprising means for adjusting belt tension.

[10] The drive belt assembly according to any one of [1] to [9], further comprising sensing means for determining malfunction or failure of the drive belt.

[11] A load handling apparatus for operating on a grid framework storage structure, the grid framework storage structure comprising: a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to said first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein said grid is supported by a set of uprights (16) forming a plurality of vertical storage locations below said grid for containers (10) to be stacked therebetween and guided vertically by said uprights through said plurality of grid spaces; The load handling apparatus comprises: A load handling device comprising: a body attached to a first set of wheels (116) arranged to engage with the first set of parallel tracks (22b) and a second set of wheels arranged to engage with the second set of parallel tracks (22a), wherein the first set of wheels (116) and the second set of wheels (118) are driven by respective drive belt assemblies described in any one of [1] to

[10] , and the first set of wheels (116) and the second set of wheels (118) are driven wheels.

[12] The load handling apparatus of

[11] , comprising four drive belt assemblies located on each side of the load handling apparatus for driving respective driven wheels.

[13] The load handling apparatus of

[11] or

[12] , further comprising a diverting assembly arranged to raise or lower the first set of wheels and / or lower or raise the second set of wheels relative to the drive wheels to engage and disengage the wheels from the parallel tracks, wherein the tensioning means of the drive belt assembly is arranged to apply pretension to the drive belt when the driven wheels are moved between a raised configuration, a lowered configuration, and a parked configuration.

[14] A kit of parts for a modular assembly for load handling equipment, comprising at least one drive belt assembly according to any one of [1] to

[13] .

[15] A grid-based storage and retrieval system comprising: a grid framework (14) structure comprising a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending in a substantially horizontal plane and substantially perpendicular to the first set of rails or tracks (22b) to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights (16) forming a plurality of vertical storage locations below the grid for containers (10) to be stacked therebetween and guided vertically through the plurality of grid spaces by the uprights; At least one load handling apparatus according to any one of [1] to

[14] , which operates on the grid framework structure; a centralized control utility for controlling the at least one load handling device(s); 1. A grid-based storage and retrieval system comprising:

Claims

1. A load handling device for lifting and moving storage containers (10) stacked on a grid framework (14) structure, comprising: a first set of parallel rails or tracks (22b) and a second set of parallel rails or tracks (22a) extending substantially perpendicular to said first set of rails or tracks (22b) in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein said grid is supported by a set of uprights (16) forming a plurality of vertical storage locations below said grid for containers (10) to be stacked therebetween and guided vertically through said plurality of grid spaces by said uprights; The load handling apparatus comprises: a body attached to a first set of wheels (116) arranged to engage the first set of parallel tracks (22b) and a second set of wheels arranged to engage the second set of parallel tracks (22a); a diverting assembly arranged to raise or lower the first set of wheels and / or lower or raise the second set of wheels relative to the body to engage and disengage the wheels from the parallel tracks; wherein the redirection assembly comprises a linkage set having a series of members disposed between a traveler and a fixed brace, wherein the traveler is arranged to move under an applied force to raise or lower a wheel.

2. A cargo handling device as described in claim 1, wherein the linkage set is a series of elastically deformable members having a compliant mechanism, or the linkage set is a series of pivotally connected rigid members.

3. A cargo handling device as described in claim 1 or 2, wherein under the applied force, the traveler is displaced horizontally relative to the fixed brace.

4. A load handling device as described in any one of claims 1 to 3, wherein the series of members each comprise a two-part linkage pivotally connected.

5. A cargo handling device as described in any one of claims 1 to 4, wherein the joints between the members of the linkage set are rotationally restricted.

6. A cargo handling apparatus as described in any one of claims 1 to 5, wherein the linkage set is stable in a neutral configuration and the linkage set is stable in at least one other configuration.

7. A cargo handling device as described in any one of claims 1 to 6, wherein the linkage set has three stable configurations.

8. The linkage set When the first set of wheels is engaged with the track, when the second set of wheels are engaged with the track, or 8. Load handling apparatus according to any preceding claim, in a stable configuration when both a first set of wheels and a second set of wheels are engaged with the tracks in a parked configuration.

9. A load handling device as described in any one of claims 1 to 8, wherein the redirection assembly comprises at least one linkage set for each set of wheels.

10. A load handling device as described in any one of claims 1 to 9, wherein the direction change assembly is arranged relative to the main body to raise or lower the first set of wheels and simultaneously lower or raise the second set of wheels, respectively.

11. A load handling apparatus as described in any one of claims 1 to 10, wherein the linkage sets are mechanically connected to move in unison between the configurations.

12. A cargo handling apparatus as described in any one of claims 1 to 11, wherein the redirection assembly further comprises a belt linking two or more linkage sets.

13. A load handling apparatus as described in any one of claims 1 to 12, wherein the direction change assembly is operated by a single motor.

14. A load handling apparatus as described in any one of claims 1 to 12, wherein the direction change assembly is operated by more than one motor.

15. A load handling apparatus as claimed in any one of claims 1 to 14, further comprising sensing means for determining engagement of the parallel tracks with the first set of wheels or the second set of wheels.

16. A load handling apparatus as described in any one of claims 1 to 15, further comprising sensing means for determining malfunction or failure of the redirection assembly.

17. A load handling apparatus as claimed in any one of claims 1 to 16, wherein the linkage set is made from plastic, polymer plastic, thermosetting plastic, thermoplastic plastic, metal, aluminium, aluminium alloy, iron, iron alloy, steel, steel alloy, magnesium, magnesium alloy, titanium, titanium alloy, zinc, zinc alloy, fibre reinforced composite material, carbon fibre, graphite fibre, glass fibre, natural fibre, plant fibre, plastic fibre, paper, cardboard, rubber, epoxy resin or nylon.

18. A load handling apparatus as described in any one of claims 1 to 17, wherein the linkage set is 3D printed and / or the linkage set is substantially topologically optimized.

19. A method of altering engagement between a set of wheels and a track of a load handling apparatus according to any one of claims 1 to 18, said load handling apparatus operating on a grid framework (14) structure comprising a track, said method comprising: applying a force F 1 in a first direction to a traveler of a diverting assembly to move the linkage set to a lowered stable configuration such that the first set of wheels engage the first set of parallel tracks; or applying a force F2 in a second direction to the traveller of the diverting assembly to move the linkage set to a lowered stable configuration such that the second set of wheels engages a second set of parallel tracks; or removing the force applied to the traveler of the turning assembly and moving the linkage set to a parked configuration in which the first and second sets of wheels are engaged with the first and second sets of parallel tracks, respectively.

20. The method of claim 1, further comprising: receiving a signal from a centralized control facility; (a) engaging the first set of wheels with the first set of parallel tracks; (b) engaging the second set of wheels with the second set of parallel tracks; or (c) engaging first and second sets of wheels with the track and first and second parallel tracks to park the load handling apparatus; and controlling the turning assembly based on the received signal.

21. When the first or second set of wheels is engaged with the track:

21. A method according to claim 19 or 20, further comprising the step of driving the set of wheels in a forward or reverse direction to steer the load handling apparatus to a position on a grid as determined by a centralized control facility.

22. A kit of parts for a modular assembly of load handling apparatus according to any one of claims 1 to 18, comprising: a body, a first set of wheels, and a second set of wheels, wherein the body may be mounted on the first set of wheels and the second set of wheels; a diverter assembly comprising at least one diverter assembly linkage set having a series of members, a traveler, and a fixed brace.

23. A kit of parts as described in claim 22, further comprising at least two direction change assembly linkage sets and a transmission belt.

24. A kit of parts as described in claim 22 or 23, further comprising at least one direction change motor.

25. A kit of parts as described in any one of claims 22 to 24, further comprising a linkage for connecting the diverter assembly to the first set of wheels and the second set of wheels.

26. A kit of parts as described in any one of claims 22 to 25, wherein at least the linkage set is 3D printed.

27. ​​A kit of parts as described in any one of claims 22 to 26, further comprising at least one of a set of wheels, a drive assembly, a gripper assembly, a lifting assembly, a communication system, and / or sensor means.

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