Winch Assembly for Load Handling Device

Abstract

A load handling device is provided for lifting and moving stacked containers (10) within a storage system comprising a lattice framework. The load handling device comprises a body housing a wheel drive mechanism and a wheel assembly. The load handling device further comprises a container lifting assembly comprising a container gripping assembly (239), a plurality of winch assemblies (243) each comprising a rotatable drum (246) and a lifting tether (238) secured at a first end to the gripping assembly (239) and at a second end to the drum (246), and a drive assembly configured to drive rotation of the drum (246) to raise the gripping assembly (239) into the container receiving space (240). Each drum (246) has an outer surface configured to accommodate a plurality of axially displaced wraps of the lifting tether (238) across the drum (246).

Description

[Technical field]

[0001] The present invention relates to the field of load handling devices for handling storage containers or bins in an automated storage system comprising stacked containers arranged in a lattice framework structure, and more particularly to a winch assembly for the load handling device. [Background technology]

[0002] Storage systems comprising a three-dimensional storage lattice framework structure in which storage containers / bins are stacked on top of each other are well known. PCT Publication No. WO2015 / 185628A (Ocado) describes a known storage and fulfillment system, in which a stack of bins or containers is arranged within the framework structure. The bins or containers are accessed by a robotically controlled load handling device operable on a truck that is positioned on top of the lattice framework structure. A system of this type is illustrated diagrammatically in Figures 1 to 3 of the accompanying drawings.

[0003] As shown in Figures 1 and 2, stackable containers known as bins 10 are stacked on top of one another to form a stack 12. The stacks 12 are arranged in a lattice framework structure 14 in a warehouse or manufacturing environment. The lattice framework structure is made up of a number of storage rows or grid rows. Each grid in the lattice framework structure has at least one grid row for storing a stack of containers. Figure 1 is a schematic perspective view of the lattice framework structure 14, and Figure 2 is a top-down view showing a stack 12 of bins 10 arranged in the lattice framework structure 14. Each bin 10 typically holds multiple product items (not shown), which may be the same or different product types depending on the application.

[0004] The lattice framework structure 14 includes a plurality of upright members 16 supporting horizontal members 18, 20. A first set of parallel horizontal members 18 are disposed at right angles to a second set of parallel horizontal members 20 to form a plurality of horizontal lattice structures supported by the upright members 16. The members 16, 18, 20 are typically fabricated from metal. The bins 10 are stacked between the members 16, 18, 20 of the lattice framework structure 14 such that the lattice framework structure 14 guards against horizontal movement of the stack 12 of bins 10 and guides vertical movement of the bins 10.

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

[0006] A known load handling device 30 shown in FIG. 4 comprises a vehicle body 32 and is described in PCT Patent Publication WO2015 / 019055 (Ocado), incorporated herein by reference. Here, the load handling device 30 comprises a wheel assembly comprising a first set of wheels 34 consisting of a pair of wheels on the front of the vehicle 32 and a pair of wheels 34 on the rear of the vehicle 32 for engaging a first set of rails or tracks to guide the movement of the device in a first direction, and a second set of wheels 36 consisting of a pair of wheels 36 on each side of the vehicle 32 for engaging a second set of rails or tracks to guide the movement of the device in a second direction. The load handling device vehicle body comprises an upper part and a lower part. The wheels are arranged in the lower part of the vehicle body around the periphery of a cavity or recess known as a container receiving recess 40. The load handling device 30 as shown in FIG. 5 comprises a lifting mechanism comprising a winch or crane mechanism for lifting storage containers or bins, also known as totes, from above, and a container gripping assembly or grabber device 39. The lifting mechanism is located on top of the vehicle body. The winch crane mechanism includes a lifting tether 38 wound on a spool or reel (not shown). A container gripping assembly 39 is configured to grip the top of the container 10 to lift the storage container 10 from a stack of containers in a storage system of the type taught in PCT Patent Publication No. WO2015 / 019055 (Ocado). The winch mechanism is driven by a drive mechanism (not shown) typically as a Z motor because the Z motor is configured to raise and lower the container gripping assembly in the Z direction when raising and lowering a storage container. During operation of the drive mechanism when lowering the container gripping assembly, the lifting tether is unwound from the spool.

[0007] During picking operations, especially when engaged with a storage container, it is essential that the container gripping assembly remains horizontal at all times, otherwise there is a potential risk that at least one of the lifting tethers holding the container gripping assembly may tear if subjected to a disproportionate high load. In order to have the necessary physical properties (Young's modulus) to withstand the load of a storage container, which can be as heavy as 35 kg, the lifting tethers are generally in the form of tapes or bands, usually made of metal (commonly a steel alloy). Typically, the container gripping assembly is constructed as a frame, with four lifting tapes fixed at or adjacent to each of the corners of the container gripping assembly, each of the four lifting tapes being wound on a separate spool. To ensure that the container gripping assembly remains horizontal, it is important that the length of all tapes is always kept the same during the operation of the container gripping assembly. To ensure that the lengths of all tethers secured to the grabber device are equal so that the container gripping assembly remains level during operation, the length of each of the tapes must be adjusted both initially and at various service intervals, as they tend to stretch or elongate over time, which may be due to many factors such as the environment, motor wear, tape stretching, etc. In the extreme case where the length of any one of the tapes is not equal, the container gripping assembly may not be able to engage the container, either because its descent is too short or because it passes over the container. Conventionally, the tapes are connected to and wound on separate reels located within the upper level of the housing or body of the load handling device. The length of travel of the lifting band per revolution of the spool on which the lifting band is wound depends on the number of layers of lifting band wound on the spool.

[0008] To adjust the tape and remove slack in the reel, the corresponding spool or reel can be disconnected from the rotating shaft and the tape adjusted by free rotation of the reel or spool relative to the rotating shaft. When the band is at the desired length, the reel or spool is then attached to the rotating shaft. A variation of this method is to provide adjustable lifting band connectors fixed to the container gripping assembly as taught in WO2019 / 206438 (Autostore Technology). Each adjustable lifting connector comprises a bracket and a band connector hub, the bracket is connected to the container gripping assembly, the band connector hub is connected to the bracket and one of the lifting bands, and movement of the band connector hub relative to the bracket adjusts the vertical distance between the respective corner of the container gripping assembly and the lifting band drive assembly.

[0009] The use of lifting tape to suspend a container gripping assembly from a spool offers the advantage that the length of tape extending between the container gripping assembly and the spool can be precisely controlled. This is because the lifting tape has a predetermined uniform thickness, allowing the number of wraps of tape wound onto the spool to be easily calculated. The tape is generally relatively thin (usually about 0.1 to 0.3 mm thick), allowing multiple overlaps of tape to be wound onto the spool. This significantly increases the length of tape that can be wound onto and unwound from the spool, thereby allowing a container gripping assembly suspended from the lifting tape to reach storage containers stored deeper within the storage system, which can be as high as 21 storage containers. However, a problem with using tape to suspend a container gripping assembly from a spool is that the tape is susceptible to damage. This is especially exacerbated when the tape is relatively thin, allowing multiple overlaps of lifting tape to be wound onto the spool. Kinking of the lifting tape affects the length of the individual tapes and therefore the separation between the spool and the container gripping assembly. Kink is a permanent crease, bend, or twist in the tape, and is especially noticeable when the lifting tape is constructed of metal. As a result, a portion of the length of the tape is wound up with a kink. Because the container gripping assembly is suspended by two or more lifting tapes, any variation in the length of any of the tapes due to a kink will affect the orientation of the container gripping assembly relative to the horizontal plane, thereby potentially affecting its ability to engage a storage container below. Replacing the tape with another type of tether, such as a rope or cable, suffers from the problem that the length of the tether cannot be precisely controlled and in particular the tethers may have to overlap or wrap around each other on the spool, thereby significantly affecting the orientation of the container gripping assembly during operation, i.e., not remaining substantially horizontal during operation.

[0010] It is therefore a primary object of the present invention to provide a lifting mechanism that is not subject to the above mentioned problems. Summary of the Invention

[0011] Applicant has alleviated the above problems by providing a plurality of winch assemblies for a load handling device operative to lift and move one or more containers stacked within a storage system comprising a lattice framework structure supporting a plurality of tracks arranged in a lattice pattern to define a lattice structure comprising a plurality of lattice cells above one or more stacks of containers, each winch assembly of the plurality of winch assemblies comprising an elongated drum rotatable about its central axis of rotation, the elongated drum having an outer surface configured to accommodate a plurality of axially displaced wraps of a lifting tether such that rotation of the drum causes the lifting tether to wrap around the outer surface of the drum.

[0012] More specifically, the present invention provides a load handling device for lifting and moving stacked containers in a storage system comprising a lattice framework comprising a plurality of lattice members arranged in a lattice pattern above a stack of containers, the load handling device comprising: i) a wheel drive mechanism operably arranged to move the load handling device on a lattice framework, and a vehicle body housing a wheel assembly comprising a first set of wheels for engaging with a first set of lattice members to guide movement of the load handling device in a first direction, and a second set of wheels for engaging with a second set of lattice members to guide movement of the load handling device in a second direction, wherein the second direction is transverse to the first direction; ii) a container lifting assembly, the container lifting assembly comprising: a) a container gripping assembly configured, in use, to releasably grip a storage container; b) a plurality of winch assemblies, each winch assembly of the plurality of winch assemblies comprising a drum rotatable about its central axis of rotation and a lifting tether having a first end secured to the container gripping assembly and a second end secured to the drum; c) a drive assembly configured to drive rotation of the drums of the plurality of winch assemblies about their respective central axes of rotation to lift the container gripping assembly into the container receiving space; Each of the drums of each of the plurality of winches is characterized by having an outer surface configured to accommodate multiple axially displaced wraps of the lifting tether across the drum such that rotation of the drum causes the lifting tether to form a helical wrap of the lifting tether about the outer surface of the drum.

[0013] In contrast to wrapping a lifting tether in the form of a tape or band around a wheel or spool to form multiple layers of overlapping lifting band, the present invention provides an elongated drum having an outer surface configured to accommodate multiple axially displaced wraps of the lifting tether over the longitudinal length of the drum such that the lifting tether is wrapped around the outer surface of the drum. Thus, instead of controlling the travel length of the lifting tape by the number of layers of lifting band wrapped around the spool, the helical wraps of the lifting tether wrapped uniformly around the rotating drum allow the travel length of the lifting tether to be precisely controlled. Thus, each helical wrap of the lifting tether wrapped around the drum accounts for a predetermined amount of the travel length of the lifting tether. The multiple helical wraps or coils of the lifting tether around the drum represent a controlled length of the lifting tether that can be paid out from the rotating drum. The drum has a uniform cross-sectional diameter such that a predetermined amount of the lifting tether is paid out per rotation of the drum. The use of an elongated drum to carry the lifting tether also increases the ability to use different types of lifting tethers connecting the drive assembly to the container gripping assembly and is not limited to the use of lifting tapes or bands as found in prior art container gripping lifting mechanisms. For example, the lifting tether can be a rope or cable or string that is sufficiently flexible and does not suffer from kinking as is present in metal type tapes or bands. Optionally, the lifting tether can include Dyneema® - an ultra-high molecular weight polyethylene (UHMwPE) material that is strong enough to be made thin enough so that multiple helical wraps can be made around the drum and still support the load of the storage container.

[0014] Preferably, each of the plurality of winch assemblies includes a guide member configured to translate axially along a direction parallel to the central axis of rotation of its respective drum to guide winding and / or unwinding of the lifting tether about the outer surface of the drum. The guide members ensure that the spiral windings of the lifting tether are distributed evenly, and optionally without overlapping, over the longitudinal length of the drum, such that the drum accommodates only a single layer of the lifting tether when the container gripping assembly is lifted into the container receiving space. The single layer of the lifting tether prevents damage to the lifting tether. For example, if the rope wraps around itself multiple times to form multiple layers before the drum is driven in the opposite direction, this will cause the lifting tether to jump down onto the last completed wrap when the container gripping assembly is lowered, thereby stressing or impacting the lifting tether. When the load from the storage container is high (e.g., typically 35 kg), the impact on the lifting tether will be correspondingly high, which under certain conditions may shorten the life of the lifting tether or damage the lifting mechanism. This causes an imbalance in the length of the lifting tether used to suspend the container gripping assembly.

[0015] In the present invention, there are two ways in which the guide member can translate across the drum to wind and unwind the lifting tether when the container gripping assembly is raised or lowered. Optionally, the guide member is movable relative to the drum in a direction parallel to the drum's central axis of rotation. For example, the outer surface of the drum is provided with a helical seat including a helical groove for receiving the helical winding of the tether, and the guide member is configured to threadably engage with the drum's helical seat, such that rotation of the drum directly controls the movement of the guide member across the drum in a direction parallel to the drum's axis of rotation. Optionally, the drum is configured to move relative to the guide member in a direction parallel to its central axis of rotation, such that rotation of the drum translates the drum along a direction parallel to the drum's central axis of rotation to guide the winding and / or unwinding of the tether around the outer surface of the drum.

[0016] Preferably, the second end of the lifting tether is secured to the drum of the respective winch assembly by being received within a recess formed in the drum. Preferably, the recess is a hole formed towards one end of the drum. Optionally, a securing mechanism is used to secure the second end of the lifting tether to the drum.

[0017] Preferably, the drive assembly comprises at least one lifting or driving shaft coupled to the drum of each of the plurality of winch assemblies and at least one motor for rotating the at least one lifting or driving shaft. For the avoidance of doubt, the terms "drive shaft" and "lifting shaft" are used interchangeably herein to mean the same feature. Preferably, the lifting shaft is coupled to the at least one motor by at least one timing belt and / or pulley system and / or gear mechanism such that the rotational motion of the at least one motor is transmitted to the at least one lifting shaft to raise and lower the container gripping assembly. Optionally, the drums of the plurality of winch assemblies are driven by at least two rotating lifting or driving shafts arranged in the body of the load handling device, where the lifting or driving shaft is further coupled to at least one motor via belt / chain and / or gear mechanism to provide a synchronous rotational motion to the at least two lifting or driving shafts. Optionally, the multiple winch assemblies comprise first and second sets of drums, and the at least one drive shaft comprises first and second drive shafts, the first set of drums mounted to the first drive shaft and the second set of drums mounted to the second drive shaft. Optionally, the at least one motor is a single motor configured to drive rotation of the first and second drive shafts. Optionally, the pulley system comprises a first drive pulley mounted to the first drive shaft and a second drive pulley mounted to the second drive shaft, where the single motor is connected to the first and second drive shafts by a single belt around the respective first and second drive pulleys such that the single motor drives rotation of the first and second sets of drums.Preferably, at least one drive shaft further comprises a motor drive shaft attached to a single motor and a motor drive pulley attached to the motor drive shaft, the single motor being connected to the first and second drive shafts by a single belt around the respective motor drive pulleys and the first and second drive pulleys, such that rotation of the motor drive shaft synchronously drives rotation of the first and second sets of drums. This arrangement allows the lifting tether to be paid out at the same speed from each drum without the need for an additional motor, thereby ensuring that the container gripping assembly remains horizontal as it is lowered. Similarly, this arrangement allows the lifting tether to be wrapped around each drum at the same speed, thereby ensuring that the container gripping assembly remains horizontal as it is raised.

[0018] Alternatively, the at least one motor comprises a plurality of motors such that the number of winch assemblies is equal to the number of motors. Preferably, the plurality of motors are driven synchronously such that the drums of the plurality of winches are driven to rotate synchronously about their respective central axes of rotation. Thus, instead of at least one motor coupled to the at least two lifting shafts via at least one timing belt and / or pulley system and / or gear mechanism, the at least two lifting shafts are rotationally driven by separate motors providing synchronous rotational movement of the at least two lifting shafts and thus the drums attached to the at least two lifting shafts.

[0019] Preferably, the plurality of winch assemblies comprises four winches such that the container gripping assembly is secured to four lifting tethers. Preferably, the container gripping assembly comprises a frame having four corners, each of the four lifting tethers being secured to one of the respective corners of the container gripping assembly. The four lifting tethers connected to the four corners of the container gripping assembly ensure that the container gripping assembly remains level during operations of raising and lowering the storage containers relative to the grid cells.

[0020] The speed at which the container gripping assembly device moves vertically also depends on the cross-sectional diameter of the drum. Thus, for a given rotational speed of the drum, a larger cross-sectional diameter of the drum results in the container gripping assembly moving faster when raised or lowered. Conversely, a smaller cross-sectional diameter results in the container gripping assembly moving slower when raised or lowered. In one aspect of the invention, at least a portion of the drum of at least one winch assembly has a variable cross-sectional diameter. Preferably, at least a portion of the drum of at least one winch assembly is tapered. By tapering at least a portion of the drum, the speed at which the container gripping assembly rises or falls can be varied. This is particularly important when the container gripping assembly is lowered to engage a storage container. As the container gripping assembly approaches the storage container, its speed is reduced to prevent the container gripping assembly from colliding with the storage container.

[0021] Optionally, the first and second sets of wheels of the wheel assembly comprise a wheel positioning mechanism configured to selectively raise and lower the first set of wheels or the second set of wheels relative to the vehicle body, thereby selectively engaging or disengaging the first set of wheels with the first set of grid members, or the second set of wheels with the second set of child members.

[0022] The wheel positioning mechanism may include one or more linkages driven by linear actuators or motors to selectively lower or raise the first set of wheels or the second set of wheels into or out of engagement with the first set of tracks or rails or the second set of tracks or rails.

[0023] The present invention further provides a storage and retrieval system, the storage and retrieval system comprising: a first set of tracks and a second set of tracks extending transversely to the first set in a substantially horizontal plane to form a grid pattern having a plurality of grid spaces or cells; a stack of containers positioned under a first set of parallel paths and a second set of parallel paths, where each of the stacks of containers occupies a single lattice space or lattice cell; and a load handling device according to the present invention arranged to traverse along the first and second sets of tracks across a plurality of grid spaces or grid cells such that when positioned above a stack of containers occupying the grid spaces or grid cells, the container lifting assembly is configured to lift at least one container from the stack of containers. [Brief description of the drawings]

[0024] Additional features and aspects of the present invention will become apparent from the following detailed description of illustrative embodiments that proceeds with reference to the drawings. [Figure 1] FIG. 1 is a schematic diagram of a lattice framework structure according to a known system. [Diagram 2] FIG. 2 is a schematic diagram of a top view showing a stack of bins arranged within the lattice framework structure of FIG. [Diagram 3] FIG. 3 is a schematic diagram of a known storage system showing load handling devices operable on a lattice framework structure. [Figure 4]FIG. 4 is a schematic perspective view of a load handling device showing a lifting device gripping a container from above. [Figure 5(a)] FIG. 5(a) is a schematic perspective cross-sectional view of the load handling device of FIG. 4 showing (a) a container accommodated within a container receiving space of the load handling device. [Figure 5(b)] FIG. 5(b) is a schematic perspective cross-sectional view of the load handling device of FIG. 4 showing the container receiving space of the load handling device (b). [Figure 6] FIG. 6 is a perspective side view of a load handling device illustrating a known lifting mechanism. [Figure 7] FIG. 7 is a perspective front view of a gripping assembly or grabber device according to an embodiment of the present invention. [Figure 8] FIG. 8 is a perspective bottom view of a container gripping assembly according to an embodiment of the present invention. [Figure 9] FIG. 9 is a perspective side view of a load handling device incorporating multiple winch assemblies in accordance with an embodiment of the present invention. [Figure 10] FIG. 10 is a different perspective view of a load handling device incorporating multiple winch assemblies in accordance with an embodiment of the present invention. [Figure 11] FIG. 11 is a bottom perspective view of a load handling device incorporating multiple winch assemblies in accordance with an embodiment of the present invention. [Figure 12] FIG. 12 is a schematic front perspective view of a load handling device carrying a storage container, in accordance with an embodiment of the present invention. [Figure 13] FIG. 13 is an exploded perspective view of a winch assembly according to an embodiment of the present invention. [Figure 14] FIG. 14 is an enlarged perspective view of a winch assembly at a different angle in accordance with an embodiment of the present invention. [Figure 15] FIG. 15 is a perspective view of a lifting drum of the winch assembly shown in FIGS. 9 through 14 in accordance with an embodiment of the present invention. [Figure 16] FIG. 16 is a perspective view of a lifting drum of a winch assembly according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The present invention contemplates known features of storage systems, such as the lattice framework structure and load handling devices described above with reference to Figures 1 to 5.

[0026] FIG. 6 shows a lifting mechanism or container lifting assembly 142 comprising a container gripping assembly 139, otherwise known as a grabber device, for releasably connecting to an underlying storage container 10, and a drive assembly 144 for raising and lowering the grabber device 139. To avoid any doubt, the terms "lifting mechanism" and "container lifting assembly" are used interchangeably in this patent specification to mean the same features. To raise and lower the gripping device 139, the lifting mechanism or container lifting assembly of prior art load handling devices comprises a set of lifting tapes or bands 138 that extend vertically between the gripping device 139 and the drive assembly 144. For maximum stability and load capacity, typically four separate lifting tapes 138 are shown extending between the drive assembly 144 and each corner of the grabber device 139. In an exemplary embodiment of the invention, the grabber device 139 is formed as a frame having four corner sections, an upper side 188 and a lower side 190 (see FIG. 7). To grip the container 10, the gripping device 139 includes four locating or guide pins 180 near or at each corner of the gripping device 139 that mate with corresponding notches or holes (not shown) formed in the four corners of the container 10. Four gripping elements 184 are located on the bottom side of the gripping device 139 for engaging the rim of the container (see Figures 7 and 8). The locating pins 180 help to properly align the gripper elements 184 with the corresponding holes in the rim of the container 10.

[0027] In the particular embodiment shown in FIG. 7, each of the gripper elements 184 comprises a pair of wings foldable to be received in a corresponding hole 186 (see FIG. 6) in the rim of the container, and an open or expanded configuration (see FIG. 6) having a size larger than the hole 186 in the rim of the container in at least one dimension to lock onto the container. The wings are actuated into the open and closed configurations by a suitable actuation mechanism coupled to a drive gear. More specifically, a head of at least one of the wings comprises a plurality of teeth that mesh with the drive gear, and when the gripper elements 184 are actuated by the actuation mechanism, rotation of the drive gear rotates the pair of wings from the closed or folded configuration to the open expanded configuration (FIGS. 7 and 8). When in the folded or closed configuration, the gripper elements 184 are sized to be received within the corresponding hole 186 in the rim of the container, as shown in FIG. 6. Each foot of the pair of wings includes a stop 188, e.g., a boss, which when received in a corresponding hole 186 in the rim of the container engages the underside of the rim when in the expanded open configuration to lock the container when the grabber device 139 is rolled upwardly towards the container receiving portion of the load handling device.

[0028] 6, each of the four lifting tapes 138 is wound on a separate spool or reel 192 that is driven in rotational motion by a drive mechanism or drive assembly 144 with a separate drive motor to raise and lower the grabber device 139. The lifting tapes 138 are wound on each spool 192 in multiple layers. To ensure that the lifting tape 138 overlaps or wraps on itself as it is wound onto the spool 192, opposing ends of the spool 192 include flanges 194 that restrain the lifting tape 138 on the spool 192. The width of the spool between the flanges is approximately the width of the lifting tape.

[0029] The drive motors 144 are typically brushless DC electric motors. The separate drive motors 144 are driven synchronously to provide synchronized rotational movement of all spools 192. This helps to keep the grabber devices 139 level during operation to allow the grabber devices, particularly the gripper elements 184, to properly engage the storage container 10. Other methods of driving the rotation of the spools are known in the art. For example, the lifting tape 138 can be wound on and unwound from the respective spools or reels 192 by being connected to at least two rotating lifting shafts (not shown) located within the body of the load handling device. The at least two lifting shafts are coupled to a suitable motor via at least one drive belt or gear to drive the rotation of the lifting shafts. To ensure that the grabber devices remain level during operation, the lengths of the lifting tape 138 between each of the drive motors 144 and the grabber devices 139 must be equal. Conventionally, to ensure that the lengths of all lifting tapes to the grabber devices are substantially equal, the length of each of the lifting tapes attached to separate reels or spools 192 must be adjusted at various service levels as they tend to stretch during use. One method in the art for adjusting the length of the lifting tapes is to decouple the spools or reels 192 from their corresponding drive shafts and subsequently remove the slack in the tape.

[0030] The lifting tapes 138 are generally thin (typically less than 0.5 mm thick) and are typically made of metal. The thinness of the lifting tape allows it to be wrapped around itself in multiple layers, providing better control of the travel length of the lifting tape as it unwinds from its corresponding spool. However, a drawback of using the lifting tape 138 to suspend the gripping device 139 is that the lifting tape can easily "kink", twist or snap, causing small portions of the lifting tape to be wound up by the kink, thereby changing the spacing between the drive motor and the gripping device secured to the "kinked" lifting tape. Because each of the lifting tapes 138 is secured to a corner of the grabber device 139, if at least one of the lifting tapes is twisted, this will change the orientation of the grabber device and it will lose its ability to keep the grabber device in a horizontal orientation, especially if the lifting tape is subsequently wound onto its respective spool. To remedy this problem, the spool 192 carrying the damaged lifting tape is removed and replaced with a new spool of lifting tape. This not only increases the cost of the lifting assembly, but also requires that the lifting tapes must be recalibrated every time a spool is replaced, increasing downtime of load handling devices operating on a lattice framework structure.

[0031] FIG. 9 shows a load handling device 230 according to an embodiment of the invention operable in the storage system 1 described with reference to FIGS. 1 and 3. The load handling device 230 comprises a frame or chassis or skeleton 231 to which body panels (not shown) are fixed externally to form a body. The body comprises an upper part and a lower part (see FIG. 9). The lower part is attached to two sets of wheels 234, 236 that run on rails on the top of the frame of the storage system (not shown). Each of the sets of wheels 234, 236 is driven to enable movement of the vehicle in the x and y directions, respectively, along the rails. One or both sets of wheels can be moved vertically by a wheel positioning mechanism that comprises one or more wheel lifting motors to lift each set of wheels off of its respective rail, thereby allowing the vehicle to move in a desired direction.

[0032] According to an embodiment of the invention, it is preferred that all of the first set of wheels 234 and the second set of wheels 236 are engaged with the respective grid members or tracks before the other first set of wheels or the second set of wheels is raised, i.e., retracted. To do this, the wheels in the retracted or raised position are first lowered to engage the grid members or tracks before the other set of wheels is raised or retracted. Lowering the set of wheels currently engaged with the grid members or tracks to engage all of the first and second sets of wheels with the grid members or tracks when the other set of wheels is in the raised position would place a large burden on one or more of the wheel lifting motors as they would have to support the full weight of the load handling device, which may reach a weight of approximately 160 kg. Similarly, lifting the vehicle to disengage a set of wheels from the grid members or tracks would place a burden on the wheel lifting motors to lift the weight of the vehicle. In a particular embodiment of the invention, the first or second set of wheels are raised or lowered once all of the first and second sets of wheels are engaged with the grid members or tracks. Thus, the wheel positioning mechanism involves a two-stage process. The first process is to engage all of the first and second sets of wheels with the grid members or tracks, and the second process involves lifting either the associated first or second set of wheels depending on whether the load handling device is moving in the X or Y direction on the grid structure.

[0033] For example, once all of the first and second sets of wheels are engaged with the grid member or tracks (i.e., in the deployed position), the load handling device is supported by all eight wheels and the associated set of wheels (first or second set of wheels) is raised or retracted depending on whether the load handling device is moving in the X or Y direction. This eliminates the need for a wheel lift motor to lift the vehicle when it is necessary to disengage the first or second set of wheels from the grid member or tracks. The first or second set of wheels are lifted to the retracted position in a synchronous manner such that all of the first or second set of wheels are lifted substantially simultaneously.

[0034] The wheels 234, 236 are arranged around the periphery of a cavity or recess known as a container receiving recess or container receiving space 240 at the bottom. The space 240 is sized to accommodate the container 10 when it is lifted by the lifting assembly 242 as shown in Figures 9 and 12. When in the container receiving space, the container is lifted off the rail below so that the load handling device can move laterally to different locations. Upon reaching the target location, for example another stack, an access point in a storage system or a belt conveyor, the bin or container can be lowered from the container receiving space and released from the grabber device 239 (see Figure 12). As shown in Figure 9, the container receiving space 240 for accommodating the container is located inside the vehicle body, but the present invention is not limited to the container receiving space 240 being located inside the vehicle body. The present invention is also applicable to container receiving spaces located below a cantilever, such as when the vehicle body of the load handling device has a cantilever structure, as described in WO2019 / 238702 (Autostore Technology AS). For the purposes of the present invention, the term "car body" is interpreted as optionally covering the cantilever such that the gripping device is positioned below the cantilever. However, for ease of explanation of the present invention, the container receiving space for receiving the container is located within a cavity or recess within the car body.

[0035] The top of the vehicle body can house most of the bulky components of the load handling device (not shown). Optionally, the vehicle body houses a rechargeable power source (not shown). Figures 9 to 12 show perspective views of the load handling device with the outer casing housing the bulky components removed. Typically, the top of the vehicle houses the lifting mechanism or container lifting assembly 242 with an on-board rechargeable power source (not shown) for powering the drive assembly of the lifting mechanism 242. The rechargeable power source may be any suitable battery, for example, but not limited to, a lithium battery or a capacitor. For the purposes of the present invention, the rechargeable power source is a battery. In the present invention, it is entirely feasible to locate any of the bulky components, such as the rechargeable power source, anywhere in the body of the vehicle, for example, at the bottom of the vehicle, to lower the center of gravity of the load handling device 230 and thereby improve the stability of the load handling device. In order to provide a container receiving space within the body of the load handling device, preferably, the rechargeable energy source is integrated into one of the side walls of the body of the vehicle. Further details of the main components of a load handling device according to the present invention are set out in International Patent Application WO2015 / 140216 (Ocado Innovation Limited), the contents of which are incorporated herein by reference.

[0036] The present invention alleviates the above-mentioned problems of the use of lifting tapes for fastening to grabber devices as described above with reference to FIG. 6 by providing a lifting mechanism or container lifting assembly 242 comprising a plurality of winch assemblies 243 as shown in FIG. 11, whereby each winch assembly 243 of the plurality of winch assemblies comprises an elongated drum 246 rotatable about its central axis of rotation (see FIG. 11). For the purposes of the specific example of the present invention, the term "elongated" is interpreted to mean that the longitudinal length of the drum is greater than the cross-sectional diameter of the drum. As with the prior art solution, the plurality of winch assemblies comprises four winch assemblies, each winch assembly of the four winch assemblies comprising a lifting tether wound around a separate drum 246 and extending between the drive assembly 244 and the grabber device 239, e.g. to a corner of the grabber frame. As described above with reference to FIG. 5, the grabber device is configured to releasably engage with a storage container stored in the storage system. In contrast to the prior art lifting mechanism, the winch assembly of the present invention comprises an elongated drum 246. Each elongated drum 246 as shown in FIG. 15 is configured such that the lifting tether extending between the drive assembly and the grabber device wraps around the outer surface of the elongated drum 246, resulting in multiple axially displaced wraps of the lifting tether wrapped around the drum. The ability of the lifting tether to wrap around the drum, as opposed to being wrapped around each other as in prior art solutions, increases the flexibility of the different types and shapes of lifting tethers used to suspend the grabber device. The lifting tether is not limited to tapes or bands, and other shapes of lifting tethers that provide increased flexibility can be used in the present invention because there is no need to control the travel length of the lifting tether by layering it in multiple layers, as in prior art solutions. For example, the lifting tether may be in the form of a rope or string or wire or cable and may include a polymeric material that provides improved flexibility and may also have sufficient tensile strength to carry the load of the storage container.One example of a lifting tether composition that provides increased tensile strength yet is flexible is a polymer material that includes ultra-high molecular weight polyethylene (UHMwPE) and is commercially available under the name Dyneema®. Dyneema® fiber is 15 times stronger than steel at the same weight, with a tensile strength of up to 43 cN / dtex. In addition to its exceptional strength, Dyneema® has excellent cut and abrasion resistance, and is highly resistant to chemicals and UV. Dyneema® fiber is also lightweight in the sense that it floats on water, yet has a very high modulus (resistance to deformation).

[0037] One end of the lifting tether is fixed to one end of the drum 246, and the lifting tether is wound back and forth between the opposing ends of the drum as the gripping device is raised and lowered. In the particular embodiment shown in FIG. 15, one end of the lifting tether is fixed to a hole or recess 248 formed in one end of the drum body 246 and can be secured to the body of the drum by a screw (not shown). The receiving hole 248 is located adjacent to one end of the drum 246 as shown in FIG. 15. Other means for securing the end of the lifting tether to the body of the drum are applicable in the present invention, such as the use of adhesives or other fastening methods commonly known in the art for securing the end of the lifting tether to the body of the drum. As the drum rotates in one direction, the lifting tether is wound continuously or spirally along the length of the drum. As the drum rotates in one direction, the lifting tether "travels" from one end of the drum to the other, wrapping the drum exterior with a layer of lifting tether. Once one end of the drum is reached, the direction of wrap can be reversed and another layer of lifting tether can be wrapped over the first layer. However, the winch assembly is preferably adapted such that the drum accommodates only a single layer of lifting tether over the length of the drum. The use of a single layer of lifting tether helps reduce wear on the lifting tether. The use of only a single layer of lifting tether may require a larger drum, length, and / or diameter to accommodate a sufficient length of lifting tether. The amount of helical wrapping of the lifting tether around the drum depends on several factors, including but not limited to: i) Cross-sectional diameter of the lifting tether ii) Cross-sectional diameter of the drum iii) Drum length iv) The number of spiral turns of the lifting tether around the drum.

[0038] For example, for a relatively small cross-sectional diameter of the lifting tether (e.g., less than 1 mm), a larger number of helical turns can be coiled around the outer surface of the drum, and thus a longer length of lifting tether can be accommodated on the drum. Because there are four winch assemblies, a balance is struck between the availability of space in the top of the vehicle to accommodate the four winch assemblies and the size of the drums for each of the winch assemblies. By using a strong material for the lifting tether, such as Dyneema® as mentioned above, a much thinner lifting tether can be used without compromising the strength of the lifting tether.

[0039] The outer surface of the drum can be provided with a helical sheet 250 (see FIG. 15) to seat the lifting tether as it is wound around the drum. The cross-sectional shape profile of the helical sheet 250 has a radius corresponding to the radius of the cross section of the lifting tether that must be wound or unwound on or from the drum outer surface. In a particular embodiment of the invention, the helical sheet is provided with a helical groove 250 around the outer surface of the drum 246. The groove may be machined into the drum or may be formed during the manufacture of the drum, for example during 3D printing or casting. The drum 246 can be formed as a single body or from separate pieces. For example, the outer surface of the drum 246 including the helical sheet can be formed as a removable shell or sleeve that can be slid onto a smaller diameter inner drum or wheel to form the drum of the invention. The removable shell allows the outer surface of the drum with the helical groove to be replaced or re-machined when the depth of the helical groove falls below a predetermined amount due to wear as a result of friction of the lifting tether against the outer surface of the drum. The "pitch" of the spiral groove is such as to accommodate multiple spiral windings of the lifting tether around the outer surface of the drum. Thus, a high pitch represents a high number of spiral grooves on the outer surface of the drum, and a low pitch represents a low number of spiral grooves on the outer surface of the drum. The drum can be constructed of a composite material, including a metallic material or a polymeric material. To improve wear resistance, the outer surface of the drum, including the spiral grooves, can be hardened, for example with hardened steel. Other more expensive materials, such as titanium, nickel, or alloys thereof, that have high hardness and therefore high wear resistance, can be used. Alternatively, the outer surface of the drum can include a ceramic material, due to its high hardness and wear resistance compared to metallic or polymeric materials. Suitable ceramic materials used to manufacture the drum, and particularly the outer surface of the drum, include, but are not limited to, silicon carbide, tungsten carbide, boron carbide, alumina, and the like. The provision of a removable shell that includes the spiral grooves provides the advantage that the outer surface can be formed separately and include more expensive materials or other exotic materials, such as ceramics.

[0040] In a particular embodiment of the invention, each winch assembly 243 of the plurality of winch assemblies comprises a guide member 248 for guiding the lifting tether 238 around the outer surface of the respective drum 246 so as to form adjacent even spiral windings of the lifting tether around the outer surface of the drum (see Figs. 13 and 14). The guide member is configured to translate along a direction parallel to the rotation axis XX of the drum (see Fig. 14). The guide member 248 ensures that the lifting tether 238 accurately follows the course of the helical sheet provided on the drum 246, thereby obtaining an efficient and uniform winding of the lifting tether on the outer surface of the drum. There are two ways in which the guide member can translate the lifting tether across the drum. In a first embodiment of the invention shown in Fig. 13, the guide member 248 is fixed and the drum 246 is configured to move relative to the guide member 248 in a direction parallel to the rotation axis of the drum. As shown in Figures 13 and 14, the guide member includes an entrance passage or aperture 241 for feeding or attaching the lifting tether to the grabber device 239 below. The entrance passage extends through the longitudinal length of the guide member. The entrance passage is oriented vertically within the guide member such that the lifting tether passes vertically through the guide member. Figure 13 shows the entrance to the entrance passage 241 and Figure 14 shows the exit from the entrance passage 241. The lifting tether 238 is guided by the guide member 248 through the entrance passage to the gripping device 239 and is secured to one corner of the gripping device, for example, at an anchor point 251 on the gripping device. The anchor point 251 can be any fastening means for securing the end of the lifting tether to the gripping device, for example, a hook, screw, etc. In the particular embodiment of the invention shown in Figures 13 and 14, the guide member 248 is formed as an upright block facing upwards and is secured to the grabber device 239. Alternatively, there may be other configurations of the guide member, for example the guide member may be an expandable tube fixed to the grabber device.Separate lifting tethers are secured to the corners of the gripping device such that the lifting tethers secured to each corner of the gripping device are guided by separate guide members from each drum of the present invention. The anchor points 251 are shown in FIG. 14 as separate fixing screws.

[0041] The drum 246 is mounted for rotational movement about a horizontal axis of rotation on a drive shaft 252 (see FIG. 14). Further details of the drive mechanism or drive assembly for driving the rotation of the drive shaft 252 are discussed below. To avoid any doubt, the terms "drive shaft" and "lifting shaft" are used interchangeably herein to mean the same feature. The drive shaft 252 not only allows for rotational movement of the drum about its central axis of rotation XX, but the drum can also move along the drive shaft in a direction parallel to its axis of rotation. This is indicated by the left and right arrows in FIG. 14. For example, the drum can be mounted on a bearing that allows the drum to slide in a direction parallel to its axis of rotation relative to the drive shaft 252, but is constrained to rotate when the drive shaft is rotated. Thus, as the drum rotates, the drum is configured to slide in an axial direction parallel to the axis of rotation of the drive shaft XX when the lifting tether 238 is guided on or off the drum 246 depending on the direction of rotation of the drum. Alternatively, the drum 246 can be fixed to the drive shaft 252, which itself can be configured to translate axially relative to the guide member 248, with the lifting tether winding or unwinding on or from the outer surface of the drum, or a combination of both configurations. For example, at least a portion of the outer surface of the drive shaft can be threadedly engaged with corresponding threads on an attachment portion 254 of the drive shaft 252 to the vehicle body or chassis (see FIG. 13 ) such that rotation of the drive shaft 252 can cause the entire drive shaft 252 to translate axially parallel to its axis of rotation.

[0042] Instead of, or in combination with, moving the drum relative to a fixed guide member, the guide member itself can be configured to move relative to the drum fixed to the drive shaft. For example, the guide member can be configured to threadably engage a helical seat on the drum such that rotation of the drum translates the guide member across the outer surface of the drum. The guide member can include an entrance passage for threading the lifting tether through the guide member and onto the outer surface of the drum where it is seated in the correct helical groove. As previously mentioned, the entrance passage may extend through the longitudinal length of the guide member. The entrance passage may be oriented vertically within the guide member such that the lifting tether passes vertically through the guide member. In certain embodiments of the invention, the drum is configured to translate axially relative to the guide member as the lifting tether 238 is wound or unwound from the drum, whereby the lifting tether wraps around the drum in multiple helical wraps. In all of the above options, the cooperation between the guide member and the drum is such that rotation of the drum about the central axis of rotation XX ensures that the helical windings of the lifting tether are accurately positioned within the helical sheet, resulting in a substantially uniform wrapping of the lifting tether around the outer surface of the drum.

[0043] A drive assembly 244 for driving the rotation of the drums 246 provides synchronous rotational movement of the drums of the multiple winch assemblies 243 about their respective axes of rotation. In a particular embodiment of the invention, the drive assembly 244 comprises at least one drive shaft 252 connected to a drive motor 255 and a drive pulley (see Figures 9 and 12) via a belt and / or chain 256. The at least one drive shaft 252 is mounted for rotational movement about a horizontal axis of rotation XX (see Figure 14).

[0044] In the particular embodiment shown in FIG. 11, the multiple winch assembly comprises a first set of drums mounted on a first drive shaft 252a and a second set of drums mounted on a second drive shaft 252b. The first set of drums includes two drums disposed at the front 258 of the load handling device, and the second set of drums includes two drums disposed at the rear of the load handling device 260. The first set of drums is mounted on a common drive shaft (first drive shaft 252a) and is separately positioned to accommodate lifting tethers secured to the front two corners of the grabber device (not shown). Similarly, the second set of drums is mounted on a common drive shaft (second drive shaft 252b) and is separately positioned to accommodate lifting tethers secured to the rear two corners of the grabber device (not shown). The first and second drive shafts 252a, 252b are driven to provide synchronous rotational movement of the first and second sets of drums by being connected to at least one drive motor 255 via a belt or chain 256. In the particular embodiment shown in Figures 9 and 12, a single drive motor 255 is connected to the first drive shaft 252a and the second drive shaft 252b via one or more drive pulleys to provide synchronous rotational motion to the first and second sets of drums. The first drive shaft 252a has a first drive pulley attached thereto, and the second drive shaft 252b has a second drive pulley attached thereto. The single motor 255 is connected to the first and second drive shafts via a single belt 256 around the first and second drive pulleys 262 of the first and second drive shafts, respectively. The single motor is configured to drive the motor drive shaft to which the motor drive pulley is attached. The single motor is connected to the first and second drive pulleys via a single belt 256 around the respective motor drive pulleys and the first and second drive pulleys 262 such that rotation of the motor drive shaft by the single motor drives rotation of the first and second sets of drums.

[0045] Each of the drums of the multiple winch assemblies includes a central core or bore 264 extending along the central axis of rotation of the drum 246 (see FIG. 15). That is, the drum is formed as a hollow cylinder. The central core 264 is formed to receive a respective drive shaft and is prevented from freely rotating about the drive shaft by a stop or groove 266 such that the drum rotates when the drive shaft rotates. In the particular embodiment shown in FIG. 15, the drum's central core 264 includes a groove 266 formed to receive a correspondingly formed ridge on the drive shaft, which prevents the drum from freely rotating about the drive shaft but allows the drum to rotate when the drive shaft rotates. Other means of attaching the drum to the drive shaft to rotate the drum when the drive shaft rotates include, but are not limited to, various splines including teeth on the drive shaft that mesh with correspondingly shaped teeth formed on the inner surface of the drum's central core. The drum may be mounted on the drum shaft in such a way that grooves or splines on the drive shaft prevent the drum from rotating freely around the drive shaft, but allow the drum to move axially along the longitudinal length of the drive shaft. As discussed above, this allows the lifting tether to wrap around the drum to form adjacent helical wraps on the drum as the drum translates axially parallel to the axis of rotation of the drum or the drive shaft. This ensures that the helical wraps of the lifting tether are precisely positioned on the outer surface of the drum, i.e., evenly wrapped on the drum. Although the specific embodiment of the invention shown in Figures 9 to 14 describes a drive assembly comprising at least one drive shaft driven by a drive motor to provide synchronous rotational movement of the drum, multiple winch assemblies may be driven by separate drive motors, as described with reference to Figure 6. Multiple winch assemblies are driven by separate motors to provide synchronous rotational movement of the drum and to keep the grabber device substantially horizontal. Other means of providing rotational movement of the drum to provide synchronous rotational movement of the drum about its respective axis of rotation are applicable in the present invention.The shape of each of the drums 246 of the multiple winch assemblies 243 is formed such that the cross-sectional diameter of the drum is uniform or substantially uniform along the longitudinal length of the drum. This allows for a fixed, predetermined length of travel of the lifting tether wrapped around the outer surface of the drum per revolution of the drum. The length of travel of the lifting tether can be approximated as the product of the circumference of the drum, given by π (pi) times the cross-sectional diameter of the drum, and the number of coils of the lifting tether wrapped around the drum. Each of the drums of the multiple winch assemblies are rotated synchronously such that the number of coils around the outer surface of each drum is substantially equal, thereby causing the length of each lifting tether extending between the drive assembly and an anchor point on the grabber device to be equal or substantially equal. This keeps the grabber device level as it is raised and lowered into the grid cell, and prevents any one of the lifting tethers from pulling harder on one of the corners of the grabber device than the other. For a given rotational speed ω of the drum, the speed at which the grabber device moves vertically depends on the cross-sectional diameter of the drum. Thus, for a given rotational speed ω of the drum, a larger cross-sectional diameter of the drum translates into a relatively greater vertical speed of the grabber device compared to a smaller cross-sectional diameter of the drum.

[0046] In another embodiment of the invention, the cross-sectional diameter of the drum can be varied to vary the vertical speed of the grabber device for a given rotational speed ω of the drum. For example, a different vertical speed of the grabber device may be required as the grabber device approaches to engage a storage container in the storage system and / or as the grabber device approaches a container receiving space in the body of the load handling device. An example of providing a drum 346 with a variable cross-sectional diameter is shown in the schematic diagram of FIG. 16. At least a portion of the drum 346 is tapered 348 such that the lifting tether is wound onto or off the drum with a variable cross-sectional diameter. In the particular embodiment shown in FIG. 16, the opposing ends 348 of the drum are tapered such that the vertical speed of the grabber device changes as the lifting tether is wound onto or unwound from the tapered portion of the drum. The opposing ends of the drum correspond to either the stage when the grabber device is approaching to engage a storage container or the stage when the grabber device is approaching a container receiving space in the body of the load handling device.

[0047] Although the illustrated embodiments described above depict the drum rotating about a horizontal axis of rotation, in other embodiments, the drum may rotate about an axis of rotation that is offset from horizontal. For example, the drum may rotate about an axis that is slightly offset from horizontal. In such embodiments, the offset of the drum's central axis can facilitate the lifting tether wrapping neatly around the drum.

[0048] It should be understood that various changes, substitutions, and alterations can be made without departing from the scope of the present invention, which is defined by the claims. The invention as originally claimed in the present application is set forth below. [1] A load handling device (30) for lifting and moving stacked containers (10) within a storage system comprising a grid framework (14) comprising a plurality of grid members arranged in a grid pattern above the stack of containers, comprising: i) a wheel drive mechanism operably arranged to move said load handling device (30) on said lattice framework (14), and a body (32) housing a wheel assembly comprising a first set of wheels (34) for engaging a first set of lattice members to guide movement of said load handling device (30) in a first direction, and a second set of wheels (36) for engaging a second set of lattice members to guide movement of said load handling device (30) in a second direction, wherein said second direction is transverse to said first direction; ii) a container lifting assembly (142, 242), said container lifting assembly (142, 242) comprising: a) a container gripping assembly (39, 239) configured to releasably grip a storage container (10) in use; b) a plurality of winch assemblies (243), each of said plurality of winch assemblies (243) comprising a drum (246) rotatable about its central axis of rotation, and a lifting tether (238) having a first end fixed to said container gripping assembly (39, 239) and a second end fixed to said drum (246); c) a drive assembly (144, 244) configured to drive the rotation of each of the drums (246) of the plurality of winch assemblies about their respective central axes of rotation to lift the container gripping assembly (39, 239) into the container receiving space (240); wherein each of the drums (246) of each of the plurality of winch assemblies has an outer surface configured to accommodate multiple axially displaced wraps of the lifting tether (238) across the drum such that rotation of the drum causes the lifting tether to form a helical wrap of the lifting tether (238) around the outer surface of the drum (246). [2] A load handling device as described in [1], wherein each of the plurality of winch assemblies includes a guide member (248) configured to translate axially along a direction parallel to the central axis of rotation of its respective drum (246) to guide winding and / or unwinding of the lifting tether (238) around the outer surface of the drum (246). [3] The load handling device described in [2], wherein the guide member (248) is movable relative to the drum (246) in a direction parallel to the central axis of rotation of the drum (246). [4] A load handling device as described in [2] or [3], wherein the drum (246) of each winch assembly is movable in a direction parallel to its central axis of rotation relative to the guide member (248) such that rotation of the drum (246) translates the guide member (248) along a direction parallel to the central axis of rotation of the drum to guide the winding and / or unwinding of the lifting tether (238) around the outer surface of the drum (246). [5] A cargo handling device as described in any one of [1] to [4], wherein the drum (246) of each winch assembly is configured to accommodate only a single layer of the lifting tether (238) when the container gripping assembly (39) is lifted into the container receiving space (240). [6] A load handling device as described in any one of [1] to [5], wherein the second end of the lifting tether (238) is secured to the drum (246) of each winch assembly by being received within a recess formed in the drum (246). [7] A load handling device as described in any one of [1] to [6], wherein the outer surface of the drum (246) of each winch assembly is provided with a spiral seat including a spiral groove (250) for receiving the spiral winding of the lifting tether (238). [8] A load handling device as described in any one of [1] to [7], wherein the drive assembly (144, 244) comprises at least one drive shaft coupled to each drum of the plurality of winch assemblies and at least one motor (144) for rotating the at least one drive shaft. [9] The cargo handling device described in [8], wherein the drive shaft is coupled to the at least one motor (144) by at least one timing belt and / or pulley system and / or gear mechanism so that rotational motion of the at least one motor (144) is transmitted to the at least one drive shaft to raise and lower the container gripping assembly (39, 239).

[10] The load handling device of [8] or [9], wherein the plurality of winch assemblies comprises first and second sets of drums, the at least one drive shaft comprises first and second drive shafts, the first set of drums is attached to the first drive shaft (252a) and the second set of drums is attached to the second drive shaft (252b).

[11] The load handling device of

[10] , wherein the at least one motor (144) comprises a single motor.

[12] The load handling device of

[11] , wherein the pulley system comprises a first drive pulley attached to the first drive shaft (252a) and a second drive pulley attached to the second drive shaft (252b), wherein the single motor is connected to the first and second drive shafts (252a, 252b) by a single belt around each of the first and second drive pulleys such that the single motor drives rotation of the first and second sets of drums.

[13] A load handling device as described in any one of [8] to

[10] , wherein the at least one motor (144) comprises a plurality of motors such that the number of winch assemblies is equal to the number of motors.

[14] A load handling device as described in

[13] , wherein the multiple motors are driven synchronously so that the drums of the multiple winch assemblies are driven to rotate synchronously about their respective central axes of rotation.

[15] A cargo handling device as described in any one of [1] to

[14] , wherein the plurality of winch assemblies comprises four winches such that the container gripping assembly (39, 239) is secured to four lifting tethers.

[16] The cargo handling device described in

[15] , wherein the container gripping assembly (39, 239) comprises a frame having four corners, and each of the four lifting tethers is secured to one of the respective corners of the container gripping assembly (39, 239).

[17] The load handling device of any one of [1] to

[16] , wherein the lifting tether (238) comprises Dyneema®.

[18] A load handling device as described in any one of [1] to

[17] , wherein the lifting tether (238) is a rope or cable or wire.

[19] A load handling device as described in any one of [1] to

[18] , wherein at least a portion of the drum (246) of at least one winch assembly has a variable cross-sectional diameter.

[20] The load handling device of

[19] , wherein at least a portion of the drum (246) of the at least one winch assembly is tapered.

[21] A cargo handling device as described in any one of [1] to

[20] , wherein the vehicle body (32) contains a container receiving space (240) such that, in use, the container lifting assembly (142, 242) is configured to releasably grasp a container (10) and lift the container from the stack into the container receiving space (240) within the vehicle body (32).

[22] A load handling device as described in any one of [1] to

[21] , wherein the first and second sets of wheels (34, 36) are provided with a wheel positioning mechanism configured to selectively raise and lower the first set of wheels (34) or the second set of wheels (36) relative to the body (32), thereby selectively engaging or disengaging the first set of wheels (34) with the first set of grid members, or the second set of wheels with the second set of grid members.

[23] A storage and retrieval system comprising: a first set of tracks and a second set of tracks extending transversely to the first set in a substantially horizontal plane to form a grid pattern having a plurality of grid spaces or cells; a stack of a plurality of containers (10) positioned under a first set of parallel paths and a second set of parallel paths, wherein each of said stacks of containers occupies a single lattice space or lattice cell; a cargo handling device (30) as described in any one of [1] to

[22] arranged to traverse along a first set and a second set of tracks across the plurality of grid spaces or grid cells such that, when positioned above a stack of containers occupying the grid spaces or grid cells, a container lifting assembly (142, 242) is configured to lift at least one container (10) from the stack of containers.

Claims

1. A load handling device (30) for lifting and moving stacked containers (10) within a storage system comprising a lattice framework structure (14) comprising a plurality of lattice members arranged in a lattice pattern above the stack of containers, the device comprising: i) a wheel drive mechanism operatively arranged to move said load handling device (30) on said lattice framework structure (14), and a body (32) housing a wheel assembly comprising a first set of wheels (34) for engaging a first set of lattice members to guide movement of said load handling device (30) in a first direction, and a second set of wheels (36) for engaging a second set of lattice members to guide movement of said load handling device (30) in a second direction, wherein said second direction is transverse to said first direction; ii) a container lifting assembly (142, 242), said container lifting assembly (142, 242) comprising: a) a container gripping assembly (39, 239) configured to releasably grip a storage container (10) in use; b) a plurality of winch assemblies (243), each of said plurality of winch assemblies (243) comprising a drum (246) rotatable about its central axis of rotation, and a lifting tether (238) having a first end fixed to said container gripping assembly (39, 239) and a second end fixed to said drum (246), each of said drums (246) of each of said plurality of winch assemblies having an outer surface configured to accommodate a plurality of axially displaced wraps of said lifting tether (238) across said drum, such that rotation of said drum causes said lifting tether to form a helical wrap of said lifting tether (238) around the outer surface of said drum (246); c) a drive assembly (144, 244) configured to drive the rotation of each of the drums (246) of the plurality of winch assemblies about their respective central axes of rotation to lift the container gripping assembly (39, 239) into the container receiving space (240); the multiple winch assembly comprises first and second sets of drums, the drive assembly comprises first and second drive shafts and a single motor, the first set of drums is attached to a first drive shaft (252a) and the second set of drums is attached to a second drive shaft (252b); a first and second drive shafts coupled to a single motor (144) by at least one timing belt and / or pulley system such that rotational motion of the single motor (144) is transmitted to the first and second drive shafts to raise and lower the container gripping assembly (39, 239).

2. A load handling device as described in claim 1, wherein the pulley system comprises a first drive pulley attached to the first drive shaft (252a) and a second drive pulley attached to the second drive shaft (252b), wherein the single motor is connected to the first and second drive shafts (252a, 252b) by a single belt around each of the first and second drive pulleys such that the single motor drives rotation of the first and second sets of drums.

3. 3. A load handling device as described in claim 1 or 2, wherein each of the plurality of winch assemblies includes a guide member (248) configured to translate axially along a direction parallel to the central axis of rotation of its respective drum (246) to guide the winding and / or unwinding of the lifting tether (238) around the outer surface of the drum (246).

4. The load handling device of claim 3, wherein the guide member (248) is movable relative to the drum (246) in a direction parallel to the central axis of rotation of the drum (246).

5. 5. A load handling device as described in claim 3 or 4, wherein the drum (246) of each winch assembly is movable in a direction parallel to its central axis of rotation relative to the guide member (248) such that rotation of the drum (246) translates the guide member (248) along a direction parallel to the central axis of rotation of the drum to guide the winding and / or unwinding of the lifting tether (238) around the outer surface of the drum (246).

6. 6. A cargo handling device as claimed in any one of claims 1 to 5, wherein the drum (246) of each winch assembly is configured to accommodate only a single layer of the lifting tether (238) when the container gripping assembly (39) is lifted into the container receiving space (240).

7. 7. A load handling device as claimed in any one of claims 1 to 6, wherein the second end of the lifting tether (238) is secured to the drum (246) of the respective winch assembly by being received within a recess formed in the drum (246).

8. 8. A load handling device as claimed in any one of claims 1 to 7, wherein the outer surface of the drum (246) of each winch assembly is provided with a spiral seat including a spiral groove (250) for receiving the spiral winding of the lifting tether (238).

9. A load handling device according to any one of claims 1 to 8, wherein the plurality of winch assemblies comprises four winches, such that the container gripping assembly (39, 239) is secured to four lifting tethers.

10. 10. The cargo handling device of claim 9, wherein the container gripping assembly (39, 239) comprises a frame having four corners, and each of the four lifting tethers is secured to one of the respective corners of the container gripping assembly (39, 239).

11. A load handling device as claimed in any preceding claim, wherein the lifting tether (238) comprises Dyneema®.

12. The load handling device of any one of claims 1 to 11, wherein the lifting tether (238) is a rope or cable or wire.

13. A load handling device according to any one of claims 1 to 12, wherein at least a portion of the drum (246) of at least one winch assembly has a variable cross-sectional diameter.

14. The load handling device of claim 13, wherein at least a portion of the drum (246) of the at least one winch assembly is tapered.

15. 15. A cargo handling device as claimed in any one of claims 1 to 14, wherein the vehicle body (32) accommodates the container receiving space (240) such that, in use, the container lifting assembly (142, 242) is configured to releasably grasp a container (10) and lift the container from the stack into the container receiving space (240) within the vehicle body (32).

16. 16. A load handling device as claimed in any one of claims 1 to 15, wherein the first and second sets of wheels (34, 36) are provided with a wheel positioning mechanism configured to selectively raise and lower the first set of wheels (34) or the second set of wheels (36) relative to the car body (32), thereby selectively engaging or disengaging the first set of wheels (34) with the first set of grid members, or the second set of wheels with the second set of grid members.

17. 1. A storage and retrieval system comprising: a first set of tracks and a second set of tracks extending transversely to the first set in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces or cells; a stack of a plurality of containers (10) positioned under a first set of parallel paths and a second set of parallel paths, wherein each of said stacks of containers occupies a single lattice space or lattice cell; and a cargo handling device (30) as claimed in any one of claims 1 to 16 arranged to traverse along a first set and a second set of tracks across the plurality of grid spaces or grid cells such that, when positioned above a stack of containers occupying a grid space or grid cell, a container lifting assembly (142, 242) is configured to lift at least one container (10) from the stack of containers.

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