LIFTING ASSEMBLY

A container lifting assembly for raising and/or lowering containers stacked in stacks in a grid storage structure, includes a gripping device configured to releasably grip a container; a raising and lowering mechanism configured to raise and lower the gripping device; and a gearing mechanism configured to wind and/or unwind at least one tether. A motor is configured to actuate the gearing mechanism to wind and/or unwind the at least one tether. The at least one tether is connected to the gripping device such that winding and unwinding of the at least one tether is configured to raise and lower the gripping device.

TECHNICAL FIELD

The present invention relates to the field of lifting assemblies. In particular, the present invention relates to lifting assemblies for load handling devices that lift and move storage containers.

BACKGROUND

Some commercial and industrial activities require systems that enable the storage and retrieval of a large number of different products. WO2015/185628A describes a storage and fulfilment system in which stacks of storage containers are arranged within a grid storage structure. The containers are accessed from above by load handling devices operative on rails or tracks located on the top of the grid storage structure.

A given load handling device lifts a target container from the top of a stack, the target container usually containing inventory items needed to fulfil a customer order. The load handling device also lowers the target container back to the top of a stack, to the top of another stack or to another location, as required. The load handling devices typically comprise a lifting assembly for lifting the container from the first location and lowering the container to the second location. The load handling device must reliably lift and lower each container from the required locations.

It is against this background that the present invention has been devised.

SUMMARY OF INVENTION

In a first aspect, there is provided a container lifting assembly for raising and/or lowering containers stacked in stacks in a grid storage structure, the lifting assembly comprising:a gripping device configured to releasably grip a container;a raising and lowering mechanism configured to raise and lower the gripping device the raising and lowering mechanism comprising:a gearing mechanism configured to wind and/or unwind at least one tether;a motor configured to actuate the gearing mechanism to wind and/or unwind the at least one tether;wherein the at least one tether is connected to the gripping device such that winding and unwinding of the at least one tether is configured to raise and lower the gripping device.

The gearing mechanism may comprise a spool (e.g. at least one spool, for example a spool for each tether). The tether (e.g. the at least one tether) may extend from the spool before extending and connecting to the gripping device. The gearing mechanism may be configured to wind and/or unwind the tether about the spool. The raising and lowering mechanism may comprise a pair of tethers (e.g. at least a pair of tethers, for example two pairs of tethers) and a spool for each pair of tethers. The gearing mechanism may be configured to wind and/or unwind the pair of tethers about the spool. The raising and lowering mechanism may comprise at least one pulley (e.g. at least one pulley for each tether). The tether may extend from the spool to the pulley before extending and connecting to the gripping device. Where the raising and lowering mechanism comprises a spool for each pair of tether, each tether in the pair of tethers may extend from the spool in opposite directions to a pulley before extending and connecting to the gripping device. The raising and lowering mechanism may comprise a pulley for each tether.

The raising and lowering mechanism may comprise at least one tether (e.g. one, two, three, four etc. tethers). The or each tether may extend from the gearing mechanism to a corner of the gripping device.

The raising and lowering mechanism may comprise a horizontally extending lifting shaft. The raising and lowering mechanism may comprise two spools, e.g. a first spool may be at a first end of the lifting shaft and/or a second spool may be at a second end of the lifting shaft, the second end being opposite the first end. The raising and lowering mechanism may comprise two tethers at the first end of the lifting shaft configured to wind and/or unwind from the first spool. The raising and lowering mechanism may comprise two tethers at the second end of the lifting shaft configured to wind and/or unwind from the second spool.

The raising and lowering mechanism may comprise four spools, e.g. two spools at the first end of the lifting shaft and/or two spools at the second end of the lifting shaft. The raising and lowering mechanism may comprise two tethers at the first end of the lifting shaft, each tether being configured to wind and unwind from a respective spool at the first end of the lifting shaft (i.e. each tether at the first end of the lifting shaft extends from its own spool). The raising and lowering mechanism may comprise two tethers at the second end of the lifting shaft, each tether being configured to wind and unwind from a respective spool at the second end of the lifting shaft (i.e. each tether at the second end of the lifting shaft extends from its own spool).

At least one spool of the raising and lowering mechanism may comprise a slip clutch (i.e. the spool may be mounted to the lifting shaft via a slip clutch). Each spool of the raising and lowering mechanism may be mounted to the lifting shaft via a respective slip clutch. At least one pulley may comprise a hard stop (e.g. a mechanical stop) against which the gripping device abuts once it reaches its fully lifted position (i.e. when the gripping device is fully lifted by the raising and lowering mechanism). Each pulley of the raising and lowering mechanism may comprise a hard stop (e.g. a mechanical stop) such that as each tether is wound to raise the gripping device, each corner of the gripping device may abut against the hard stop once it reaches its fully lifted position. The motor may be configured to rotate the lifting shaft so as to wind or unwind the tethers thereby lifting or lowering the gripping device. During lifting and/or lowering of the gripping device, the gripping device may become uneven, i.e. one side of the gripping device may be higher than the other side, or one or more corners of the gripping device may be higher than the remaining corners of the gripping device. As the gripping device is lifted to its fully lifted position, the gripping device side that is higher or the corner(s) that are higher may reach their fully lifted positions and abut against the hard stops before the uneven lower side or corner(s) of the gripping device reach the hard stops.

To level an uneven gripping device, the motor may over rotate the lifting shaft so as to bring up the uneven lower side or lower corner(s) of the gripping device. During this over driving or over rotation of the motor, the slip clutch(es) at the side or corner(s) already at the fully lifted position can slip and prevent further rotation of those spools, thereby keeping the side or corner(s) already at the fully lifted position abutted against the hard stops. The motor may over elevate the gripping device against the hard stops each time the gripping device is raised. The slip clutch(es) may allow the motor to over rotate the lifting shaft and bring up any uneven lower side or corner(s) of the gripping device, while keeping any side or corner(s) of the gripping device already at the fully lifted position abutted against the hard stops. In this way, the lifting assembly can calibrate and level the gripping device each time the gripping device is raised.

The slip clutch may be centrally located on the spool and may include a shaft or hollow bore which is mounted to the lifting shaft, thereby mounting the spool to the lifting shaft. The slip clutch may be a spring clutch or an electromagnetic clutch (e.g. a permanent magnet clutch or a hysteresis/magnetic particle clutch). The slip clutch may be a fixed torque or an adjustable torque clutch.

The gearing mechanism may be provided on the gripping device. As the gearing mechanism winds the tether (e.g. the at least one tether), the gripping device may climb towards the top of the lifting assembly, i.e. as opposed to being pulled to the top of the lifting assembly (e.g. in embodiments where the gearing mechanism is not provided on the gripping device, for example above the gripping device and/or in the load handling device). The motor may be provided on the gripping device. As such, the gripping device may be self-powered, i.e. the gripping device may use power from the motor on the gripping device (i.e. and may not require power from the load handling device).

The gearing mechanism may comprise a planetary gear set or a worm gear or any other gearing mechanism suitable for winding and/or unwinding tethers.

The tether(s) may be in the form of cables, ropes, tapes or any other form of tether with the necessary physical properties to lift the containers. The tethers may be formed of or comprise polyester material (e.g. woven polyester material). In particular, the tethers may comprise woven polyester tapes or belts, e.g. seat belts (i.e. seat belts may be used as the tethers). The tethers may comprise dyneema tape. The tethers may comprise polyester material (e.g. woven polyester) combined with dyneema tape. The tethers may comprise cotton material. The tethers may comprise webbing material, e.g. webbed polyester, nylon, cotton. The tethers may comprise conductive material, for example the tethers may comprise woven material or woven polyester material with a conductive element or wiring (e.g. copper) woven into the weave or fabric of the tethers. The tethers may comprise woven belts (e.g. seat belts) with a conductive element or wiring woven into the belt. The tethers may comprise a conductive element or wiring (e.g. copper) woven into the weave or fabric of the tethers so as to provide power and/or communication (i.e. electrical communication) to the gripping device. In another aspect, there is provided a container lifting assembly according to the first aspect, wherein the raising and lowering mechanism comprises:a horizontally extending lifting shaft, a first spool, a second spool, a third spool, and a fourth spool, wherein the first and second spools are located at or near a first end of horizontally extending lifting shaft, and the third and fourth spools are located at or near a second end opposite the first end of the horizontally extending lifting shaft; anda first tether, a second tether, a third tether, and a fourth tether configured to wind and unwind from the first, second, third, and fourth spools respectively, wherein the first and second spools are configured to rotate in an opposite direction to the third and fourth spools to wind and unwind the first, second, third, and fourth tethers.

The first and second spools may be on a first shaft, the third and fourth spools may be on a second shaft, wherein the gearing mechanism may comprise first and second pulleys on the first and second shafts respectively, the first and second pulleys driven via a timing belt in opposite directions.

The gearing mechanism further may further comprise third and fourth pulleys arranged about either the first or second pulley to effect opposite rotation of the first and second pulleys via the timing belt.

Any one of the first, second, third, and fourth pulleys may be driven directly by the motor.

The gearing mechanism may comprise first and second worm gears on a shaft driven by the motor, wherein the worm gears are configured to effect rotation of the first and second spools in the opposite direction to the third and fourth spools.

The first and second spools may be on a first shaft, the third and fourth spools may be on a second shaft, wherein the gearing mechanism may further comprise first and second gears on the first and second shafts respectively, the first and second gears driven via the first and second worm gears respectively.

In another aspect, there is provided a container lifting assembly according to the first aspect, wherein the raising and lowering mechanism comprises:a horizontally extending lifting shaft, a first spool, a second spool, a third spool, and a fourth spool, wherein the first and second spools are located at or near a first side of and adjacent to a centre axis of the horizontally extending lifting shaft, and the third and fourth spools are located at or near a second side of and adjacent to the centre axis, wherein the first side is opposite the second side; anda first tether, a second tether, a third tether, and a fourth tether configured to wind and unwind from the first, second, third, and fourth spools respectively, wherein the first and second spools are configured to rotate in an opposite direction to the third and fourth spools to wind and unwind the first, second, third, and fourth tethers.

The first and second spools may be on a first shaft, the third and fourth spools may be on a second shaft, the first and second shafts parallel to the central axis.

The gearing mechanism may comprise first and second gears on the first and second shafts respectively, wherein the first and second gears mesh such that the motor driving either the first or second shaft rotates the other of the first or second shafts.

Each tether may be coupled to a respective pulley located at or near a respective corner of the lifting assembly.

In any of the above aspects, the first, second, third, and fourth tethers are configured such that a point at which each tether winds and unwinds to or from a respective spool or pulley is at or near a respective corner of the lifting mechanism.

Each tether may connect to the gripping device at or near a respective corner of the gripping device.

In any of the above aspects, the at least one spool comprises at least one groove along its circumference into which a wire tether is configured to wind.

In another aspect, there is provided a load handling device for lifting and moving containers stacked in stacks in a grid storage structure comprising a plurality of tracks arranged in a grid pattern above the stacks of containers, the load handling device comprising:

a body housing a driving mechanism operatively arranged for moving the load handling device on the grid;

a container lifting assembly as described above, configured to raise and lower the gripping device relative to the body and for raising and lowering containers stacked in stacks.

The lifting assembly may be located within the body of the load handling device. The lifting assembly may raise a container into the body (e.g. into a cavity of the load handling device).

The tethers may comprise a conductive element or wiring (e.g. copper) woven into the weave or fabric of the tethers so as to provide power and/or communication (i.e. electrical communication) between the load handling device (e.g. a power source or a communication source provided in the body of the load handling device) and the gripping device.

In another aspect, there is provided a load handling device for lifting and moving containers stacked in stacks in a grid storage structure comprising:a first set of parallel tracks and a second set of parallel tracks extending substantially perpendicularly to the first set of tracks 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 to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces; the load handling device comprising:a body mounted on a first set of wheels being arranged to engage with the first set of parallel racks and a second set of wheels being arranged to engage with the second set of parallel tracks, the body housing a drive mechanism configured to drive the load handling device on the grid;a container lifting assembly as described above, configured to raise and lower the gripping device relative to the body and for raising and lowering containers stacked in stacks.

In another aspect, there is provided a method of raising and/or lowering a container from a stack of containers, the method comprising the load handling device as described above, the method comprising the steps of:actuating the gearing mechanism so as to unwind the at least one tether and lower the gripping device relative to the bodyactuating the gripping device to grip a containeractuating the gearing mechanism so as to wind the tethers and raise the gripping device relative to the body.

The method may comprise the step of raising the gripping device relative to the body and lifting the container into a cavity of the load handling device.

In another aspect, there is provided a system comprising:a load-handling device as defined above;a storage structure for accommodating containers stacked in stacks, the storage structure including a first set of tracks extending in a first direction and a second set of tracks extending in a second direction transverse to the first direction, the load-handling device configured to move on the first and second sets of tracks,a control utility configured to control the load handling device to lift a container from a stack beneath the grid and/or lower a container into the grid.

DETAILED DESCRIPTION

FIG.1illustrates a storage structure1comprising upright members3and horizontal members5,7which are supported by the upright members3. The horizontal members5extend parallel to one another and the illustrated x-axis. The horizontal members7extend parallel to one another and the illustrated y-axis, and transversely to the horizontal members5. The upright members3extend parallel to one another and the illustrated z-axis, and transversely to the horizontal members5,7. The horizontal members5,7form a grid pattern defining a plurality of grid cells. In the illustrated example, storage containers9are arranged in stacks11beneath the grid cells defined by the grid pattern, one stack11of containers9per grid cell.

FIG.2shows a large-scale plan view of a section of track structure13forming part of the storage structure1illustrated inFIG.1and located on top of the horizontal members5,7of the storage structure1illustrated inFIG.1. The track structure13may be provided by the horizontal members5,7themselves (e.g. formed in or on the surfaces of the horizontal members5,7) or by one or more additional components mounted on top of the horizontal members5,7. The illustrated track structure13comprises x-direction tracks17and y-direction tracks19, i.e. a first set of tracks17which extend in the x-direction and a second set of tracks19which extend in the y-direction, transverse to the tracks17in the first set of tracks17. The tracks17,19define apertures15at the centres of the grid cells. The apertures15are sized to allow containers9located beneath the grid cells to be lifted and lowered through the apertures15. The x-direction tracks17are provided in pairs separated by channels21, and the y-direction tracks19are provided in pairs separated by channels23. Other arrangements of track structure may also be possible.

FIG.3shows a plurality of load handling devices31moving on top of the storage structure1illustrated inFIG.1. The load handling devices31, which may also be referred to as robots or bots, are provided with sets of wheels to engage with corresponding x- or y-direction tracks17,19to enable the bots31to travel across the track structure13and reach specific grid cells. The illustrated pairs of tracks17,19separated by channels21,23allow bots31to occupy (or pass one another on) neighbouring grid cells without colliding with one another.

As illustrated inFIG.4, the bot31comprises a body33in or on which are mounted one or more components which enable the bot31to perform its intended functions. These functions may include moving across the storage structure1on the track structure13and raising or lowering containers9(e.g. from or to stacks11) so that the bot31can retrieve or deposit containers9in specific locations defined by the grid pattern.

The illustrated bot31comprises first and second sets of wheels35,37which are mounted on the body33of the bot31and enable the bot31to move in the x- and y-directions along the tracks17and19, respectively. In particular, two wheels35are provided on the shorter side of the bot31visible inFIG.4, and a further two wheels35are provided on the opposite shorter side of the bot31(not visible inFIG.4). The wheels35engage with the tracks17and are rotatably mounted on the body33of the bot31to allow the bot31to move along the tracks17. Analogously, two wheels37are provided on the longer side of the bot31visible inFIG.4, and a further two wheels37are provided on the opposite longer side of the bot31(not visible inFIG.4). The wheels37engage with the tracks19and are rotatably mounted on the body33of the bot31to allow the bot31to move along the tracks19.

The bot31also comprises a lifting assembly102comprising a raising and lowering mechanism39configured to raise and lower containers9. The illustrated raising and lowering mechanism39comprises four tethers41which are connected at their lower ends to a gripping device100. The tethers41may be in the form of cables, ropes, tapes, or any other form of tether with the necessary physical properties to lift the containers9. The gripping device100comprises at least one gripper configured to engage with features of the containers9. For example, the containers9may be provided with one or more apertures in their upper sides with which the gripper can engage. Alternatively or additionally, the gripper may be configured to hook under the rims or lips of the containers9, and/or to clamp or grasp the containers9. The tethers41may be wound up or down to raise or lower the gripping device100, as required. One or more motors or other means may be provided to effect or control the winding up or down of the tethers41.

As can be seen inFIG.5, the body33of the illustrated bot31has an upper portion45and a lower portion47. The upper portion45is configured to house one or more operation components (not shown). The lower portion47is arranged beneath the upper portion45. The lifting assembly102is in an upper part of the lower portion. However, in other embodiments, it may be in the upper portion45. The lower portion47comprises a container-receiving space or cavity for accommodating at least part of a container9that has been raised by a lifting assembly102that comprises the raising and lowering mechanism39. The container-receiving space is sized such that enough of a container9can fit inside the cavity to enable the bot31to move across the track structure13on top of storage structure1without the underside of the container9catching on the track structure13or another part of the storage structure1. When the bot31has reached its intended destination, the lifting assembly102controls the tethers41to lower the gripping device100and the corresponding container9out of the cavity and into the intended position. The intended position may be a stack11of containers9or an egress point of the storage structure1(or an ingress point of the storage structure1if the bot31has moved to collect a container9for storage in the storage structure1). Although in the illustrated example the upper and lower portions45,47are separated by a physical divider, in other embodiments, the upper and lower portions45,47may not be physically divided by a specific component or part of the body33of the bot31.

The container-receiving space of the bot31may not be within the body33of the bot31. For example, the container-receiving space may instead be adjacent to the body33of the bot31, e.g. in a cantilever arrangement with the weight of the body33of the bot31counterbalancing the weight of the container to be lifted. In such embodiments, a frame or arms of the raising and lowering mechanism39may protrude horizontally from the body33of the bot31, and the tethers41may be arranged at respective locations on the protruding frame/arms and configured to be raised and lowered from those locations to raise and lower a container into the container-receiving space adjacent to the body33. The height at which the frame/arms is/are mounted on and protrude(s) from the body33of the bot31may be chosen to provide a desired effect. For example, it may be preferable for the frame/arms to protrude at a high level on the body33of the bot31to allow a larger container (or a plurality of containers) to be raised into the container-receiving space beneath the frame/arms. Alternatively, the frame/arms may be arranged to protrude lower down the body33(but still high enough to accommodate at least one container between the frame/arms and the track structure13) to keep the centre of mass of the bot31lower when the bot31is loaded with a container.

To enable the bot31to move on the different wheels35,37in the first and second directions, the bot31includes a wheel-positioning mechanism for selectively engaging either the first set of wheels35with the first set of tracks17or the second set of wheels37with the second set of tracks19. The wheel-positioning mechanism is configured to raise and lower the first set of wheels35and/or the second set of wheels37relative to the body33, thereby enabling the load handling device31to selectively move in either the first direction or the second direction across the tracks17,19of the storage structure1.

The wheel-positioning mechanism may include one or more linear actuators, rotary components or other means for raising and lowering at least one set of wheels35,37relative to the body33of the bot31to bring the at least one set of wheels35,37out of and into contact with the tracks17,19. In some examples, only one set of wheels is configured to be raised and lowered, and the act of lowering the one set of wheels may effectively lift the other set of wheels clear of the corresponding tracks while the act of raising the one set of wheels may effectively lower the other set of wheels into contact with the corresponding tracks. In other examples, both sets of wheels may be raised and lowered, advantageously meaning that the body33of the bot31stays substantially at the same height and therefore the weight of the body33and the components mounted thereon does not need to be lifted and lowered by the wheel-positioning mechanism.

FIGS.6A,6B and6Cshow perspective views of the load handling device31with an embodiment of gripping device100suspended from the load handling device31, in particular from the load handling device body33. Although not shown in these figures, the load handling device31includes the features described above in relation to the load handling device or bot31, including the first and second sets of wheels35,37mounted to the body of the load handling device31, the cavity for receiving at least part of the container and the reeled tethers41connected at their lower ends to the gripping device100for connecting and suspending the gripping device100from the load handling device31. The load handling device31comprises the lifting assembly102which winds or unwinds the reeled tethers41, the tethers being wound and unwound respectively to raise and lower the gripping device100as shown inFIGS.6A,6B and6C. The gripping device100is lowered onto a container to be lifted, until it contacts with an upper rim of the container9. Once the gripping device100is into position on the container9as shown inFIG.6C, the gripping device100engages and grips the container.

FIGS.7and8show an embodiment of the lifting assembly102,FIG.7showing a front view of the lifting assembly102andFIG.8showing a top view of the lifting assembly102. In this embodiment, the lifting assembly102includes a raising and lowering mechanism39comprising a rectangular support plate104, a centrally located motor106, a gearing mechanism108and four pulleys110a,110b,110c,110dfastened or connected to an underside of the support plate104. In this embodiment, the gearing mechanism108is a planetary gear set (e.g. an epicyclic gear set) with a vertically extending lifting shaft112which rotates to wind or unwind the tethers. Each pulley110a,110b,110c,110dis located at or towards a corner of the lifting assembly102, in particular at each corner of the support plate104, and the tethers extend from the planetary gear set to the four pulleys110a,110b,110c,110d, before extending downwards such that a lower end of each pulley110a,110b,110c,110dconnects to the gripping device100. The motor106is configured to rotate the lifting shaft112so as to wind or unwind the tethers about the lifting shaft thereby lifting or lowering the gripping device110. By winding or unwinding the tethers about the lifting shaft112, the lifting shaft112in effect provides a spool for the tethers. As the motor106rotates the lifting shaft112in a first direction, the tethers are simultaneously wound about the lifting shaft112so as to lift the gripping device100. The motor106rotates the lifting shaft in a second direction (opposite to the first direction) to simultaneously unwind the tethers from the lifting shaft112and lower the gripping device100. The motor106rotates the lifting shaft112such that the tethers are wound and unwound at the same rate. In this embodiment, the motor106is located above the support plate104. By centrally locating the motor106on the support plate104(as shown inFIG.8), the weight of the motor106is evenly distributed across the lifting assembly102. Furthermore, by providing the motor106on the support plate104, the added weight of the motor106on the lifting assembly102can advantageously ensure a more stable lifting and lowering of the gripping device100.

FIG.9shows a top view of the lifting assembly102ofFIGS.7and8and shows the tethers114a,114b,114c,114dextending from the planetary gear set108to the four pulleys110a,110b,110c,110d. As shown inFIG.9, each pulley110a,110b,110c,110dis angled towards the planetary gear set (i.e. towards the center of the lifting assembly102or the center of the support plate104). By angling the pulleys110a,110b,110c,110dtowards the center, the tethers114a,114b,114c,114dextend in a straight line from the center of the lifting assembly102(or from the gearing mechanism108) to the pulleys. This allows the lifting assembly102to wind and unwind the tethers114a,114b,114c,114d(and thus lift and lower the gripping device100) more evenly and more steadily without the risk of the tethers114a,114b,114c,114dgetting stuck or tangled with each other as they are wound or unwound by the gearing mechanism108.

FIG.10shows another embodiment of lifting assembly102. In this embodiment, the raising and lowering mechanism39includes a central horizontally extending lifting shaft116and two spools, a first spool118aat a first end of the lifting shaft and a second spool118bat a second end of the lifting shaft116. Four pulleys110a,110b,110c,110dare provided at each corner of the lifting assembly102, in particular at each corner of the support plate104and, in this embodiment, are located above the support plate104. At each end of the lifting shaft116, two tethers extend from each spool in opposite directions and through a respective pulley110a,110b,110c,110dbefore extending downwards such that the lower end of each tether114a,114b,114c,114dconnects to the gripping device100. As shown byFIG.10, by providing the pulleys110a,110b,110c,110dat or towards each corner of the support plate104, the tethers114a,114b,114c,114dcan extend downwards such that the lower ends of each tether114a,114b,114c,114dconnect to a corner of the gripping device100, thereby providing a more stable lifting and lowering of the gripping device100.

The lifting shaft116is configured to rotate so as to wind or unwind the tethers114a,114b,114c,114dabout each spool118a,118b. As the lifting shaft116is rotated in a first direction, the two tethers114a,114bat the first end of the lifting shaft are wound about the first spool118a, and simultaneously, the two tethers114c,114dat the second end of the lifting shaft are wound about the second spool118b, thereby lifting the gripping device100(and a container when gripped by the gripping device). The lifting shaft116is rotated in a second direction (opposite the first direction), to simultaneously unwind the two tethers114a,114bfrom the first spool118aand the two tethers114c,114dfrom the second spool118b, thereby lowering the gripping device100(and a container when gripped by the gripping device). By providing two spools118a,118b, one on each end of the lifting shaft116, each spool winds or unwinds two tethers, thereby reducing the risk of tangling of the tethers. Each spool118a,118bmay include grooves to keep the two tethers being wound on the spool separate, thereby further reducing the risk of tangling of the tethers.

FIGS.11A-Cshow views of one of the spools118a,118bfrom the embodiment ofFIG.10.FIG.11Cshows a section view through the section A-A inFIG.11B. The arrows shown inFIG.11Cillustrate the direction of the two tethers114a,114b,114c,114dthat extend from each spool118a,118b. As shown byFIG.11C, the tethers114a,114b,114c,114dextend in opposite directions such that each tether114a,114b,114c,114dcan be simultaneously unwound from the spool or wound from the spool.

FIG.12shows another embodiment of lifting assembly102. In this embodiment, the raising and lowering mechanism includes a central horizontally extending lifting shaft and four spools118a,118b,118c,118d, two spools at each end of the lifting shaft, i.e. two spools118a,118bat the first end of the lifting shaft116and two spools118c,118dat the second end of the lifting shaft116. As with the embodiment ofFIG.10, four pulleys110a,110b,110c,110dare provided at each corner of the support plate104. In this embodiment, each tether114a,114b,114c,114dextends from its own respective spool118a,118b,118c,118dand through a respective pulley110a,110b,110c,110dbefore extending downwards where the lower end of each tether connects to a corner of the gripping device. Each of the four tethers is connected to its own spool and extends through its own pulley before connecting to the gripping device100. By providing four spools (i.e. one for each tether) each spool has a single tether that is wound or unwound on it, thereby further reducing the risk of tangling of the tethers. Furthermore, by providing a spool for each tether, the wound tether, when fully wound onto the spool (i.e. when the tether is completely wound onto the spool) occupies less space compared to embodiments where two or more tethers are wound onto a single spool. For example, by providing a spool for each tether, the wound tether will occupy half the amount of space compared to embodiments where two tethers are wound onto a single spool. This advantageously results in the lifting assembly102requiring less space in the load handling device31body33, for example, the lower portion47of the load handling device31comprising the container-receiving space for accommodating the lifting assembly102and at least part of the container. In other words, by providing a spool for each tether, the lifting assembly102advantageously allows for space gain in the container-receiving space.

As the lifting shaft is rotated in a first direction to wind the tethers, each tether is simultaneously wound about its respective spool so as to lift the gripping device (and a container when gripped by the gripping device). The lifting shaft is rotated in a second direction (opposite the first direction), to simultaneously unwind each tether from its respective spool, thereby lowering the gripping device (and a container when gripped by the gripping device).

In the embodiments ofFIGS.10and12, the tethers connect to the gripping device100via four further pulleys (one at each corner of the gripping device). However, in other embodiments, the lower end of each tether may connect to the gripping device without the need for further pulleys (e.g. the lower end of the tethers may connect directly to the gripping device100).

Although not shown in the embodiments ofFIGS.10and12, a motor106is provided to rotate the lifting shaft in the first and second directions. In each of the embodiments ofFIGS.7-12, the motor106is configured to rotate the lifting shaft such that all the tethers are wound or unwound simultaneously and at the same rate so as to lift and lower the gripping device evenly and steadily.

In some embodiments, each spool is mounted to the lifting shaft via a respective slip clutch. As the lifting shaft is rotated by the motor in the first direction, the tethers are wound to lift the gripping device. Once the gripping device100reaches its top or fully lifted position (i.e. the gripping device100is fully lifted by the raising and lowering mechanism39e.g. into the body33of the bot31), the motor can over drive beyond the torque of the slip clutches such that the slip clutches slip and the spools no longer rotate. Each pulley comprises a hard stop (e.g. a mechanical stop) against which the gripping device abuts once it reaches its fully lifted position.

By providing a slip clutch for each spool, the lifting assembly102can level the gripping device100should the gripping device100become uneven (e.g. during lowering and/or lifting of the gripping device or due to stretching or slipping of one or more of the tethers). For example, in the embodiment ofFIG.10, the gripping device may become uneven during lowering and/or lifting of the gripping device such that a first end of the gripping device (i.e. the end lifted by the first spool at the first end of the lifting shaft) reaches its fully lifted position and abuts against the hard stops at the pulleys, while a second end of the gripping device (i.e. the end lifted by the second spool at the second end of the lifting shaft) has not yet reached its fully lifted position. The motor continues to rotate (i.e. over rotates) the lifting shaft such that the second end of the gripping device is lifted to its fully lifted position and abuts against the hard stop at the pulley. During this over rotation of the motor to rotate the lifting shaft and lift the second end of the gripping device, the slip clutch at the first spool slips and prevents further rotation of the first spool, thereby keeping the first end of the lifting shaft at its fully lifted position.

In the embodiment ofFIG.10, a slip clutch is provided at each spool, thereby allowing the lifting assembly102to level any unevenness between the first end and the second end of the gripping device.

In some embodiments ofFIG.12, a slip clutch is provided at each spool and each pulley comprises a hard stop (e.g. a mechanical stop) against which the gripping device abuts once it reaches its fully lifted position. As described above, by providing a slip clutch at each spool, the lifting assembly102is able to level the gripping device should it become uneven during lowering and/or lifting. If a side or a corner of the gripping device becomes uneven, the motor continues to rotate the lifting shaft until the uneven side or corner is lifted to its fully lifted position and abuts against the hard stop at the pulley. In the embodiment ofFIG.12a spool is provided for each tether. As such a slip clutch can be provided at each spool to control the level of each individual tether. This advantageously allows the lifting assembly102to control and level each corner of the gripping device should it become uneven.

The motor over elevates against the hard stops each time the gripping device is lifted. This allows any side or corner of the gripping device that is uneven to be lifted to the hard stop. The slip clutches at each spool allow the motor to over rotate to lift any side or corner of the gripping device that is uneven, while keeping any side or corner of the gripping device already at the fully lifted position abutted against the hard stops. This advantageously allows the lifting assembly to calibrate and level the gripping device each time the gripping device is raised.

In embodiments including slip clutches, the slip clutch is centrally located on the spool (seeFIG.11C) and includes a shaft or a hollow bore which is mounted to the lifting shaft, thereby mounting the spool to the lifting shaft. The slip clutch is preferably an electromagnetic clutch (e.g. a hysteresis/magnetic particle clutch). These clutches operate via electric actuation, in particular where actuation of the clutch does not require touching of the internal elements of the clutch, thereby reducing wear of the clutch over time. By providing an electromagnetic clutch, these advantageously provide a reliable and durable method for levelling the gripping device. The slip clutch is a fixed torque clutch which slips at a predetermined torque.

In the embodiments ofFIGS.7-10and12, the lifting assembly102includes a support plate104for supporting the spools. The support plate104can also be provided to support the motor106as shown in the embodiment ofFIGS.7-9. However, in other embodiments, the support plate104may not be necessary. The spools and/or the motor106may be supported by alternative support means, including, for example one or more vertical shafts.

FIG.13shows a raising and lowering mechanism139of another embodiment of lifting assembly102. In this embodiment, the raising and lowering mechanism139includes a central horizontally extending lifting shaft120and four spools, two spools122a,122bat the first end of the lifting shaft120and two spools122c,122dat the second end of the lifting shaft120. The lifting assembly102comprises four pulleys124a,124b,124c,124d, one at each corner of the lifting assembly102, and four tethers114a,114b,114c,114d, each tether extending from a respective spool122a,122b,122c,122dto a respective pulley124a,124b,124c,124dbefore extending downwards where a lower end of each tether114a,114b,114c,114dconnects to the gripping device100, e.g. a corner of the gripping device (not shown inFIG.13). The two tethers114a,114bat the first end of the lifting shaft extend in opposing directions from the two spools122a,122bat the first end of the lifting shaft120and the two tethers114c,114dat the second end of the lifting shaft120extend in opposing directions from the two spools122c,122dat the second end of the lifting shaft such that each tether can pass through a pulley at the corner of the lifting assembly102. In this embodiment, each of the four tethers is connected to its own spool such that a single tether is wound or unwound on each spool. This advantageously ensures that the wound tethers on each spool occupy less space compared to embodiments where two or more tethers are wound onto a single spool, for example as described in relation to the embodiment ofFIG.12. Providing a spool for each tether also advantageously reduces the risk of tangling of the tethers as they are wound and unwound to lift and lower the gripping device.

In some embodiments, the raising and lowering mechanism139ofFIG.13includes slip clutches at each spool, i.e. each spool is mounted to the lifting shaft via a respective slip clutch, as described in relation to the embodiment ofFIG.12. As described above, this allows the lifting assembly102of the embodiment ofFIG.13to level each corner of the gripping device100should it become uneven during lifting and/or lowering.

In other embodiments, the lifting assembly102may comprise two spools, one at each end of the lifting shaft and the spools may comprise one or more grooves to separate the two tethers on each spool.

The lifting shaft is configured to rotate so as to wind or unwind the tethers about each spool. As the lifting shaft is rotated in a first direction to wind the tethers, each tether is simultaneously wound about its respective spool so as to lift the gripping device (and a container when gripped by the gripping device). The lifting shaft is rotated in a second direction (opposite the first direction), to simultaneously unwind each tether from its respective spool, thereby lowering the gripping device (and a container when gripped by the gripping device). The tethers are wound or unwound simultaneously and at the same rate so as to lift or lower the gripping device evenly and steadily.

The lifting assembly102includes a motor106configured to rotate the lifting shaft120in the first and second directions so as to wind or unwind the tethers about their spools. The motor106is coupled to the central horizontally extending lifting shaft120so as to rotate the lifting shaft in the first and second directions.

The motor106is encased or partially surrounded by a block which protects the motor106and aids in holding the motor106in place. The four pulleys124a,124b,124c,124dare also held within blocks which are suspended or connected to the load handling device by vertical rods (not shown), thereby connecting the lifting assembly102to the load handling device.

The blocks are also connected by rods128which assemble each pulley124a,124b,124c,124dto a corner of the rectangular lifting assembly102. Each block holding a pulley124a,124b,124c,124dincludes a cutout to allow the tether114a,114b,114c,114dto extend from the spool to the pulley within the block.

FIGS.14A and14Bshow another embodiment of lifting assembly102. In this embodiment, the lifting assembly102includes a raising and lowering mechanism239comprising a gearing mechanism130provided on the gripping device. The gearing mechanism130winds and unwinds four tethers114a,114b,114c,114d, which connect to the gearing mechanism130via four pulleys132a,132b,132c,132dlocated at the corners of the gripping device100. The tethers114a,114b,114c,114dextend upwards from the pulleys on the gripping device100to four pulleys110a,110b,110c,110dlocated within the body33of the load handling device31. As the gearing mechanism130winds the tethers114a,114b,114c,114d, the gripping device100climbs upwards towards the load handling device31. Due to the gearing mechanism130being on the gripping device100, it can be described that the gripping device100‘climbs’ as the gearing mechanism130winds the tethers, rather than the gripping device100being lifted as the tethers114a,114b,114c,114dare wound for example when the gearing mechanism is provided above the gripping device (e.g. in the load handling device body33). In other words, the lifting power comes from the gripping device100rather than from a gearing mechanism provided in the body33of the load handling device31. As the gearing mechanism130unwinds the tethers114a,114b,114c,114d, the gripping device100is lowered.

Providing the gearing mechanism130on the gripping device100adds weight to the gripping device100. This advantageously helps the gripping device100in being lifted and lowered in a more smooth, level and steady way (e.g. compared to lighter gripping devices).

As shown inFIG.14B, the raising and lowering mechanism239comprises a motor106which is configured to drive or rotate the gearing mechanism130so as to wind or unwind the tethers. The motor106is provided on the gripping device100. This advantageously provides further weight on the gripping device100, aiding the gripping device100in being lifted and lowered in a smooth and level way. By providing the gearing mechanism130and/or the motor106on the gripping device100, the lifting assembly102achieves a redistribution of its mass which advantageously results in a more smooth, level and steady lifting and lowering of the gripping device100.

Furthermore, by providing the motor106on the gripping device100, the gripping device100itself is powered without the need for power cables to extend from a powered load handling device31to the gripping device100. By providing the motor106on the gripping device100, the gripping device100can act as an autonomous element that can be tasked with a mission (e.g. pick a container at a particular location in the storage structure and11containers deep). The gripping device100can use its own source of power and sensors (where provided) to carry out the task. The gripping device100can use its own power from the motor106to drive other elements on the gripping device100(e.g. sensors, grippers, LEDs etc).

The motor106and the gearing mechanism130are centrally located on the gripping device100. This helps to ensure the gripping device100stays level as it rises and lowers. In this embodiment, the gearing mechanism130is a planetary gear set (e.g. an epicyclic gear set) with a vertically extending lifting shaft134which acts as a spindle for the tethers114a,114b,114c,114das the gear set130rotates to wind or unwind the tethers.

In other embodiments, the motor106may be provided in the load handling device.

In some embodiments, the raising and lowering mechanism239may include a weight on the gripping device100to add weight to the gripping device instead of or in addition to providing the gearing mechanism130and/or the motor106on the gripping device100.

FIG.15shows another embodiment of lifting assembly102. In this embodiment, the raising and lowering mechanism339includes a gearing mechanism in the form of a worm gear136mounted on a horizontally extending central shaft138which, in this embodiment, are located within the load handling device body33. Although not shown, the lifting assembly102includes a motor106(e.g. in the load handling device body33) which rotates or drives the worm gear136to wind or unwind four tethers114a,114b,114c,114dwhich spool about the worm gear136. The worm gear136includes four circumferential grooves or tracks along the outside of the worm gear (i.e. the drum of the worm gear) into which the tethers wind or unwind. By providing four separate circumferential grooves, each tether can wind and unwind from the worm gear in its own groove, thereby reducing or eliminating the risk of tangling between the tethers as the worm gear rotates.

As the worm gear rotates to wind the tethers and lift the gripping device100, the worm gear136travels or slides along the shaft138in a first axial direction (e.g. towards the right). As the worm gear rotates to unwind the tethers and lower the gripping device100, the worm gear136travels or slides back along the shaft138in an opposite direction (i.e. opposite the first axial direction e.g. towards the left). By allowing the worm gear to travel backwards and forwards (towards the right or left) along the shaft138as the tethers are wound or unwound from the worm gear136ensures a more smooth and even winding and unwinding of the tethers from the worm gear136. The worm gear136can travel along the shaft138due to the force of the tethers as they wind or unwind from the worm gear136. In other embodiments, the gearing mechanism includes a spring that can bias the worm gear backwards and forwards along the shaft138as the tethers are wound or unwound.

In some embodiments, the drum of the worm gear136may be mounted to the shaft138via an ultra-low friction rail. This allows the turning force of the worm gear136alone to be sufficient to cause the tethers to wind and unwind from the worm gear and move the worm gear backwards and forwards on the shaft138. In other words, the worm gear can ‘auto feed’ the tethers. Examples of ultra-low friction material that may be used include PTFE. The skilled person will know of a number of other suitable materials for the ultra-low friction rail.

The tethers114a,114b,114c,114dextend downwards from the worm gear136to four pulleys142a,142b,142c,142don the gripping device100, located approximately centrally on the gripping device100so as to keep the tethers114a,114b,114c,114dtowards the centre of the lifting assembly102. This results in a more space efficient lifting assembly102which requires less space within the load handling device31. Keeping the tethers114a,114b,114c,114dtowards the centre in this way also results in an easier spooling of the tethers114a,114b,114c,114dabout the worm gear136. From the centrally located pulleys142a,142b,142c,142d, the tethers extend along the gripping device to four pulleys144a,144b,144c,144dat the corners of the gripping device100. This ensures a more stable and level lifting and lowering of the gripping device as the tethers114a,114b,114c,114dare wound and unwound by the worm gear136.

In the embodiment ofFIG.15, a single substantially centrally located worm gear is provided to wind and unwind the tethers. In other embodiments, the lifting assembly includes a gearing mechanism in the form of two worm gears, each worm gear configured to wind and unwind two tethers. By providing two worm gears rather than one, the weight of the gearing mechanism may be more evenly distributed across the lifting assembly102, resulting in a more balanced lifting assembly102. Furthermore, by providing two worm gears each supporting two tethers, winding and unwinding of the tethers may be simplified and the risk of tangling of the tethers as they are wound and unwound from the worm gears may be reduced or eliminated.

In the above embodiments, all of the cables are spooled and unspooled using a single motor106. However, in other embodiments, more than one motor106may be used if desired. In the embodiment ofFIG.16, a lifting assembly102has four spools201,202,203, and204to wind and unwind respective tethers. Spools201and202are on drive shaft205, whereas spools203and204are on drive shaft206. Drive shafts205and206, when driven by a motor, are configured to rotate in opposite directions. By rotating drive shafts205and206in opposite directions, respective tethers114a-dcan be located at or near the corners of the lifting assembly, as with the embodiments above. In particular, as shown inFIG.16, the point at which each tether winds or unwinds to or from a spool is at or near a respective corner of the lifting assembly. This allows the tethers to connect to the gripping assembly100at a respective corner of the gripping assembly, which increases stability when raising and lowering the gripping assembly.FIG.16shows one example of how drive shafts205and206can be rotated in opposite directions. Drive shafts205and206are connected to pulleys210and211respectively. A motor applies torque to pulley207. Timing belt208transmits the torque to pulleys209,210, and211in a way that ensures spools201and202, and spools203and204rotate in opposite directions. In particular, pulleys207and209are arranged about pulley211to effect its opposite rotation to pulley210. It will be appreciated that this is only one example way in which drive shafts205and206can be made to rotate in opposite directions when driven by a motor.

Whilst not limiting, it will be appreciated that the spools201,202,203, and204are particularly suited to the woven polyester tapes, or woven belts (e.g. seat belts) with a conductive element or wiring woven into the belt described above. Where a wire tether is used, each spool201,202,203, and204may be threaded to form a groove that receives/releases the wire tether as it is wound/unwound. Such a spool500is shown inFIG.17, and this spool can be used with any of the embodiments described above. The depth of the groove510, and the overall configuration of the grooves may be chosen depending on the properties of the wire515such as diameter and length.

Additionally, a slip clutch may be included at each spool, i.e. each spool201,202,203, and204is mounted to the lifting shaft via a respective slip clutch, as described in relation to the embodiments ofFIGS.12and13. As described above, this allows the lifting assembly102to level each corner of the gripping device100should it become uneven during lifting and/or lowering.

In the embodiment ofFIG.18, a lifting assembly102has four spools301,302,303, and304to wind and unwind respective tethers114a-d. Spools301and302are on drive shaft305, whereas spools303and304are on drive shaft306. Drive shafts305and306, when driven by a motor, are configured to rotate in opposite directions. Drive shafts are operatively coupled by the meshing of gears307and308. Drive shaft305(and thus gear307, and spools301and302) and drive shaft306(and thus gear308, and spools303and304) are on opposite sides of and adjacent to a central axis310of the lifting assembly. The central axis310extends in a longitudinal direction that is parallel to the longitudinal axes of drive shafts305and306. The tethers from each spool extend to respective pulleys311,312,313, and314located at or near the corners of the lifting assembly, as with the embodiments above. In particular, as shown inFIG.18, the point at which each tether winds or unwinds to or from a pulley311,312,313, and314is at or near a respective corner of the lifting assembly. This allows the tethers to connect to the gripping assembly100at a respective corner of the gripping assembly, which increases stability when raising and lowering the gripping assembly. When either drive shaft305,306is driven by a motor to rotate in a first direction, the other drive shaft rotates in a second direction opposite the first direction through the meshing of gears307and308. That is, gear307(and thus spools301and302), and gear308(and thus spools303and304) rotate in opposite directions to wind and unwind respective tethers. It will be appreciated that this is only one example way in which drive shafts305and306can be made to rotate in opposite directions when driven by a motor.

Whilst not limiting, it will be appreciated that the spools301,302,303, and304are particularly suited to the woven polyester tapes, or woven belts (e.g. seat belts) with a conductive element or wiring woven into the belt described above. Where a wire tether is used, each spool301,302,303, and304may be threaded to form a groove that receives/releases the wire tether as it is wound/unwound. Such a spool500is shown inFIG.18, and this spool can be used with any of the embodiments described above. The depth of the groove510, and the overall configuration of the grooves may be chosen depending on the properties of the wire515such as diameter and length.

Additionally, a slip clutch may be included at each spool, i.e. each spool301,302,303, and304is mounted to the lifting shaft via a respective slip clutch, as described in relation to the embodiments ofFIGS.12and13. As described above, this allows the lifting assembly102to level each corner of the gripping device100should it become uneven during lifting and/or lowering.

In the embodiment ofFIG.19, a lifting assembly102has four spools401,402,403, and404to wind and unwind respective tethers. Spools401and402are on drive shaft405, whereas spools403and404are on drive shaft406. Drive shafts405and406, when driven by a motor, are configured to rotate in opposite directions. By rotating drive shafts405and406in opposite directions, the tethers can be located at or near the corners of the lifting assembly, as with the embodiments above. In particular, as shown inFIG.19, the point at which each tether winds or unwinds to or from a spool is at or near a respective corner of the lifting assembly. This allows the tethers to connect to the gripping assembly at a respective corner of the gripping assembly100, which increasing stability when raising and lowering the gripping assembly.FIG.19shows one example of how drive shafts405and406can be rotated in opposite directions. A motor applies torque to a shaft411comprising a first worm gear407and a second worm gear408. First and second worm gears407,408are configured (or threaded) such that they rotate respective gears409and410in opposite directions. Gear409thus rotates drive shaft405in a first direction, and gear410rotates drive shaft406in a second direction opposite the first direction. That is, gear409(and thus spools401and402), and gear409(and thus spools403and404) rotate in opposite directions to wind and unwind respective tethers.

Whilst not limiting, it will be appreciated that the spools401,402,403, and404are particularly suited to the woven polyester tapes, or woven belts (e.g. seat belts) with a conductive element or wiring woven into the belt described above. Where a wire tether is used, each spool401,402,403, and404may be threaded to form a groove that receives/releases the wire tether as it is wound/unwound. Such a spool500is shown inFIG.17, and this spool can be used with any of the embodiments described above. The depth of the groove510, and the overall configuration of the grooves may be chosen depending on the properties of the wire515such as diameter and length.

Additionally, a slip clutch may be included at each spool, i.e. each spool401,402,403, and404is mounted to the lifting shaft via a respective slip clutch, as described in relation to the embodiments ofFIGS.12and13. As described above, this allows the lifting assembly102to level each corner of the gripping device100should it become uneven during lifting and/or lowering. All optional and preferred features and modifications of the described embodiments and dependent claims are usable in all aspects of the invention taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.