Patent Description:
Document <CIT> describes, in accordance with its abstract, an automated storage and retrieval system comprising a container handling vehicle comprising a transport mechanism for transport of the vehicle on the rail system. The container handling vehicle further comprises a lifting assembly for picking up storage containers from storage columns to a position above the lowest level of the transport mechanism, wherein the lifting assembly comprises a lifting frame connectable to a storage container, a first lifting shaft and a second lifting shaft of equal or near equal diameter. The first and second lifting shafts are mainly parallel, and each of the first and second lifting shafts are supported in an upper portion of the vehicle. Two lifting elements extend from each of the first and second lifting shafts to the lifting frame, a motor drive assembly comprising at least a first motor, wherein the at least first motor encircles one of the lifting shafts. A force transferring assembly rotatably connects the first and second lifting shafts via a force transferring element It further describes a container handling vehicle as well as method of operating the automated storage and retrieval system.

Document <CIT> describes, in accordance with its abstract, a storage system comprising a storage grid comprising vertical column profiles defining a plurality of grid columns, the grid columns comprising storage columns, in which storage containers can be stored one on top of another in vertical stacks. The storage grid comprises at least one rail grid at the upper ends of the column profiles, a first container handling vehicle and a second container handling vehicle, the first and the second container handling vehicles each comprising at least one wheel base unit and a first container handling module or a second container handling module, respectively, connected to the wheel base unit. Each wheel base unit has a wheel arrangement for movement of the wheel base unit in two perpendicular directions upon a rail grid of the storage system, and a horizontal periphery fitting within the horizontal area defined by a grid cell of the rail grid such that wheel base units may pass each other on any adjacent grid cells of the rail grid, each of the wheel base units comprises an upper surface configured as a connecting interface for connection to any of the first and second container handling modules, and the first container handling module is a different type of container handling module to the second container handling module.

<FIG> discloses a typical prior art automated storage and retrieval system <NUM> with a framework structure <NUM> and <FIG> discloses two different prior art container handling vehicles <NUM>,<NUM> suitable for operating on such a system <NUM>.

Containers <NUM> stored in the columns <NUM> are accessed by the container handling vehicles through access openings/ grid openings <NUM> in the grid cells <NUM> in the rail system <NUM>.

At least one of set wheels 201b,301b,201c,301c can be lifted and lowered, so that the first set of wheels 201b,301b and/or the second set of wheels 201c,301c can be engaged with the respective set of rails <NUM>, <NUM> at any one time.

Each prior art container handling vehicle <NUM>,<NUM> also comprises a lifting device (not shown) for vertical transportation of storage containers <NUM>, e.g. raising a storage container <NUM> from, and lowering a storage container <NUM> into, a storage column <NUM>. The lifting device comprises one or more gripping / engaging devices which are adapted to engage a storage container <NUM>, and which gripping / engaging devices can be lowered from the vehicle <NUM>,<NUM> so that the position of the gripping / engaging devices with respect to the vehicle <NUM>,<NUM> can be adjusted in a third direction Z which is orthogonal the first direction X and the second direction Y. Parts of the gripping device of the container handling vehicle <NUM> is shown in in <FIG> and is indicated with reference number <NUM>. The gripping device of the container handling device <NUM> is located within the vehicle body 301a in <FIG>.

The storage volume of the framework structure <NUM> has often been referred to as a grid <NUM>, where the possible storage positions within this grid is referred to as a storage cell. Each storage column may be identified by a position in an X- and Y-direction, while each storage cell may be identified by a container number in the X-, Y and Z-direction.

Such a vehicle is described in detail in e.g. <CIT> or e.g. <CIT>.

The central cavity container handling vehicles <NUM> shown in <FIG> may have a footprint that covers an area with dimensions in the X and Y directions which is generally equal to the lateral extent of a storage column <NUM>, e.g. as is described in <CIT>. The term 'lateral' used herein may mean 'horizontal'.

The rail system <NUM> typically comprises rails with grooves into which the wheels of the vehicles are inserted. Each rail may comprise one track, or each rail may comprise two parallel tracks (so-called "double tracks" which is described in relation to <FIG> below).

Within the art, such a location is normally referred to as a 'port' and the column in which the port is located may be referred to as a `port column' <NUM>,<NUM>.

The access station may typically be a picking or a stocking station where product items are removed from or positioned into the storage containers <NUM>. In a picking or a stocking station, the storage containers <NUM> are normally not removed from the automated storage and retrieval system <NUM>, but are returned into the framework structure <NUM> again once accessed. A port can also be used for transferring storage containers to another storage facility (e.g. to another framework structure or to another automated storage and retrieval system), to a transport vehicle (e.g. a train or a lorry), or to a production facility.

When a storage container <NUM> is to be stored in one of the columns <NUM>, one of the container handling vehicles <NUM>,<NUM> is instructed to pick up the storage container <NUM> from the pick-up port column <NUM> and transport it to a location above the storage column <NUM> where it is to be stored. After any storage containers positioned at or above the target position within the storage column stack <NUM> have been removed, the container handling vehicle <NUM>,<NUM> positions the storage container <NUM> at the desired position. The removed storage containers may then be lowered back into the storage column <NUM>, or relocated to other storage columns.

It is a drawback with the prior art container handling vehicles of the cantilever type that they can only transport one storage container at the time.

One objective of the invention is to provide a container handling vehicle of the cantilever type that can transport more than one storage container at the time.

The invention is set forth in the independent claims while the dependent claims describe alternatives of the invention.

The invention relates to a container handling vehicle for operation on a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of container handling vehicles in a first direction X across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second direction which is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the container handling vehicle comprises:.

In an aspect, when a storage container is positioned on the upper surface, an uppermost part of the storage container represents a first height; and the lifting device comprises a lifting frame that is suspended from the cantilever section, the lifting frame having a lowermost part at a second height when the lifting frame is docked in an upper position adjacent the cantilever section; wherein the second height, when the lifting frame is docked in its upper position, is above the first height, such that the lowermost part of a docked lifting frame of a first container handling vehicle can pass over the uppermost part of a storage container positioned on the upper surface of a lower section of the body unit of a second container handling vehicle when the first and second container vehicles pass one another on adjacent grid cells.

Other robots or human operator(s) can handle/pick items stored in the storage container positioned on the first container carrying position. the storage container positioned on the first container carrying position could thus make for a useful place to hold items that need regular access. At the same time it also provides a useful counterbalance for the vehicle when it needs to pick up heavy storage containers.

The first container carrying position may be recessed to provide sideways support for a storage container positioned on the first container carrying position.

The lifting device may comprise a lifting device motor and at least two lifting shafts, and wherein the at least two lifting shafts may be arranged in the cantilever section and the lifting device motor may be arranged in the lower section, and wherein the lifting device motor and at least two lifting shafts may be connected to each other via a drive coupling. The drive coupling may comprise any necessary components to transfer rotational movement from the lifting device motor and the lifting shafts.

The lifting device may comprise a lifting device motor and at least two lifting shafts arranged in the cantilever section.

The body unit may comprise an S-shaped housing linking the lower section, the support section and the cantilever section together. The S-shape is the shape that is seen when the housing is viewed from the side.

The first container carrying position may comprise a conveyor for transferring a storage container between the first container carrying position and an external support. The external support may be an external conveyor. In order to ease transfer of storage containers, an upper surface of the external support is preferably at the same height as an upper surface of the conveyor on the first container carrying position.

A footprint of the lower section of the body unit may be displaced with respect to the footprint of the wheel base unit by substantially or equally a width of a wheel. Footprint shall in this instance be understood as that the vertical projection of the lower section does not step into an adjacent grid cell when the lower section is arranged directly above a grid cell.

The lifting frame may be suspended on lifting bands, and the lifting frame may extend horizontally and comprise gripping devices and corner guides, where a lowermost point of the corner guides may provide the lowermost part of the lifting frame. The lifting bands are preferably electrically and/or signally conductive such that power and instructions can be provided to the gripping devices on the lifting frame.

It is further described an automated storage and retrieval system comprising a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of container handling vehicles in a first direction X across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second direction Y which is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the automated storage and retrieval system comprises a plurality of container handling vehicles as defined above.

The wheel base unit with the first and second sets of wheels may be equal to a grid cell.

Two container handling vehicles, which have the same orientation, may occupy only three grid cell spaces along one row when passing each other along that row.

The first set of rails and or the second set of rails may comprise either a single track or a double track comprising two single tracks, and a grid cell may be defined as the horizontal area occupied by a grid opening delimited by the first and second set of rails in addition to the area occupied by single tracks in the first and second directions enclosing a single grid opening.

The wheel base unit may have a footprint equal to a horizontal extent in the first and second directions of a grid cell.

The container handling vehicle may comprise a support surface, wherein the support surface may provide a second container carrying position.

The second container carrying position may be arranged above the first container carrying position. Preferably, the second container carrying position has the same vertical projection as the first container carrying position. If arranged on a rail system, the size of the support section is preferably equal to or less than a grid cell. As an alternative to a second container carrying position, two or more storage containers may be stacked on top of each other where all of the stacked storage containers are supported by the first container carrying position.

The second container carrying position may be movable between:.

The second container carrying position may be movable between the retracted position and the extended position via a pivot connection. The pivot connection may be such that:.

The pivot connection could alternatively be arranged such that the second surface could be made to flip over onto the roof of the cantilever section. For example, it could be a hinge connection along the corner edge of the back of the cantilever at the top that connects to that section, the ends of the arms then resting against the vertical surfaces of the support section.

The second container carrying position may be linearly movable between the retracted position and the extended position via a linear movement arrangement. If using a linear movement arrangement, the linear movement arrangement can be arranged such that:.

The second container carrying position may be provided with a conveyor, i.e., it can self-offload the storage container at the second container carrying position independently of the storage container at the first container carrying position through use of the conveyor and some receiving infrastructure that can catch a high level container coming off the conveyor. If the first container carrying position is provided with a conveyor, any storage container at the first container carrying position may be offloaded without first having to offload the storage container positioned at the second container carrying position. If both the first and second container carrying position are provided with conveyors, any storage container positioned on the first and/ or second container carrying positions can be dispatched independently of the other storage container by using the conveyor.

It is further described a method of transferring a storage container between a first and second container handling vehicle as defined above, the first and second container handling vehicles operating on an automated storage and retrieval system comprising a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of container handling vehicles in a first direction X across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second direction Y which is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the method comprises the steps of:.

The step of transferring a storage container between the upper surface of the lower section of the second container handling vehicle and the lifting device of the first container handling vehicle may comprise the steps of:.

The get_bin command may include a parameter defining a height of the storage container to be transferred such that the lifting device of the master vehicle is lowered to a position equal to an uppermost part of the storage container positioned on the first container carrying position. The height of the storage container is the distance between the lifting device in the docked upper position and to the top of the storage container. This distance may vary dependent on the height of the storage container and whether the storage container is positioned on the first container carrying position or a container carrying position at another elevation.

The step of setting the other container handling vehicle as a slave vehicle may include a step of sending a synchronize_to_master command to the slave vehicle such that the slave vehicle moves with and follows the master vehicle.

After the step of sending a synchronize_to_master command to the slave vehicle the method may further comprise a step of sending a message from the slave vehicle to the main control system when the slave vehicle moves with and follows the master vehicle.

It is further described a method of transferring a storage container between a container handling vehicle as defined above and an external container carrying position, the container handling vehicle operating on an automated storage and retrieval system comprising a two-dimensional rail system comprising a first set of parallel rails arranged to guide movement of container handling vehicles in a first direction X across the top of the frame structure, and a second set of parallel rails arranged perpendicular to the first set of rails to guide movement of the container handling vehicles in a second direction Y which is perpendicular to the first direction, the first and second sets of parallel rails dividing the rail system into a plurality of grid cells, wherein the method comprises the steps of:.

The relative terms "upper", "lower", "below", "above", "higher" etc. shall be understood in their normal sense and as seen in a cartesian coordinate system.

In the following, numerous specific details are introduced by way of example only to provide a thorough understanding of embodiments of the claimed system and vehicle. One skilled in the relevant art, however, will recognize that these embodiments can be practiced without one or more of the specific details, or with other components, systems, etc. In other instances, well-known structures or operations are not shown, or are not described in detail, to avoid obscuring aspects of the disclosed embodiments.

In the drawings, like reference numerals have been used to indicate like parts, elements or features unless otherwise explicitly stated or implicitly understood from the context.

In the following, embodiments of the invention will be discussed in more detail by way of example only and with reference to the appended drawings.

The rail system <NUM> may be a single rail (also denoted single track) system, as is shown in <FIG>. Alternatively, the rail system <NUM> may be a double rail (also denoted double track) system, as is shown in <FIG>, thus allowing a container handling vehicle <NUM> having a footprint generally corresponding to the lateral area defined by an access opening/ grid column <NUM> to travel along a row of grid columns even if another container handling vehicle <NUM> is positioned above a grid column neighboring that row. Both the single and double track system, or a combination comprising a single and double track arrangement in a single rail system <NUM>, forms a grid pattern in the horizontal plane P comprising a plurality of rectangular and uniform grid locations or grid cells <NUM>, where each grid cell <NUM> comprises a grid opening <NUM> being delimited by a pair of tracks 110a,110b of the first set of rails <NUM> and a pair of tracks 111a,111b of the second set of rails <NUM>. In <FIG> the grid cell <NUM> is indicated by a dashed box. For example, the sections of the rail-based system being made of aluminium are the rails, and on the upper surface of the rails, there are a pair of tracks that the wheels of the vehicle run in.

However, the sections could be separate rails each with a track.

Consequently, tracks 110a and 110b form pairs of rails defining parallel rows of grid cells running in the X direction, and tracks 111a and 111b form pairs of rails defining parallel rows of grid cells running in the Y direction.

As shown in <FIG>, each grid cell <NUM> has a width Wc which is typically within the interval of <NUM> to <NUM>, and a length Lc which is typically within the interval of <NUM> to <NUM>. Each grid opening <NUM> has a width Wo and a length Lo which is typically <NUM> to <NUM> less than the width Wc and the length Lc of the grid cell <NUM>.

In the X and Y directions, neighboring grid cells are arranged in contact with each other such that there is no space therebetween.

<FIG> is a perspective view of a prior art container handling vehicle <NUM> having a cantilever for carrying storage containers underneath.

An exemplary wheel base unit for a container handling vehicle <NUM> according to the invention is shown in <FIG>. The wheel base unit <NUM> features a wheel arrangement 32a,32b having a first set of wheels 32a for movement in a first direction upon a rail system <NUM> and a second set of wheels 32b for movement in a second direction perpendicular to the first direction. Each set of wheels comprises two pairs of wheels arranged on opposite sides of the wheel base unit <NUM>. To change the direction in which the wheel base unit may travel upon the rail system, one of the sets of wheels 32b is connected to a wheel displacement assembly <NUM>. The wheel displacement assembly is able to lift and lower the connected set of wheels 32b relative to the other set of wheels 32a such that only the set of wheels travelling in a desired direction is in contact with the rail system. The wheel displacement assembly <NUM> is driven by an electric motor <NUM>. Further, two electric motors <NUM>,<NUM>', powered by a rechargeable battery <NUM>, are connected to the set of wheels 32a,32b to move the wheel base unit in the desired direction.

Further referring to <FIG>, the horizontal periphery of the wheel base unit <NUM> is dimensioned to fit within the horizontal area defined by a grid cell, such that two wheel base units <NUM> may pass each other on any adjacent grid cells of the rail system <NUM>. In other words, the wheel base unit <NUM> may have a footprint, i.e. an extent in the X and Y directions, which is generally equal to the horizontal area of a grid cell, i.e. the extent of a grid cell in the X and Y directions, e.g. as is described in <CIT>.

<FIG> is a simplified side-view of a container handling vehicle <NUM> according to an embodiment of the invention comprising a wheel base unit <NUM> and a body unit <NUM>, where the body unit <NUM> comprises a lower section <NUM>, a support section <NUM> and a cantilever section <NUM>. The lower section <NUM> having an upper surface, wherein the upper surface <NUM> provides a first container carrying position <NUM> for carrying a storage container <NUM>.

Referring to <FIG> and <FIG>, the wheel base unit <NUM> has a top panel/flange <NUM> (i.e. an upper surface) configured as a connecting interface for connection to a body unit <NUM> of a container handling vehicle <NUM>. The top panel <NUM> have a centre opening <NUM> and features multiple through-holes <NUM> (i.e. connecting elements) suitable for a bolt connection via corresponding through-holes in a lower section <NUM> of the body unit <NUM>. In other embodiments, the connecting elements of the top panel <NUM> may for instance be threaded pins for interaction with the through-holes of the lower section <NUM>. In yet another embodiment, the container handling vehicle <NUM> is not in this modular design, but rather made in one or a few pieces. The presence of a centre opening <NUM> is advantageous as it provides access to internal components of the wheel base unit <NUM>, such as the rechargeable battery <NUM> and an electronic control system <NUM>.

Further referring to <FIG>, the body unit <NUM> is disclosed as comprising an S-shaped housing linking the lower section <NUM>, the support section <NUM> and the cantilever section <NUM> together. The container handling vehicle <NUM> of <FIG> is operable on a rail system <NUM> as described in connection with <FIG>, and comprises a wheel base unit <NUM> and a body unit <NUM>. The wheel base unit <NUM> comprising sets of wheels 32a, 32b for guiding the container handling vehicle <NUM> along the rail system <NUM> in the first and second directions X, Y. The body unit <NUM> comprising a lower section <NUM>, a support section <NUM> and a cantilever section <NUM>. The lower section <NUM> is mounted on an upper surface of the wheel base unit <NUM>. The lower section <NUM> may have a footprint with a horizontal extent which is equal to or less than the horizontal extent of one of the grid cells <NUM>. The top of the storage container <NUM> is at a first height h1. the first height h1 is the distance from the top of the rail system <NUM> to the top of the storage container <NUM> positioned on the first container carrying position on the upper surface the lower section <NUM> when the lower section <NUM> is mounted on the wheel base unit <NUM>. The support section <NUM> extends vertically from the lower section <NUM> and has a footprint with a horizontal extent which is smaller than the footprint of the lower section <NUM>. The width of the support section <NUM> (i.e. the extension in the X direction) may be equal to the width of the lower section <NUM> (in the X direction). The extension of the support section <NUM> in the Y direction is smaller than the extension of the lower section <NUM> in the Y direction.

Furthermore, referring to <FIG>, when seen in a plan view from above, the footprint of the support section <NUM> falls within the footprint of the lower section <NUM>. In other words, as disclosed in <FIG>, the support section <NUM> does not extend beyond the lower section <NUM>. The cantilever section <NUM> extends horizontally from the support section <NUM> beyond the footprint of the lower section <NUM> and comprises a lifting device <NUM> suspended from the cantilever section <NUM>.

The lifting device <NUM> comprising a lifting frame <NUM> having a lowermost part at a second height h2 when the lifting frame <NUM> is docked in an upper position adjacent the cantilever section <NUM> (<FIG> show docked position of lifting frame <NUM>). the second height h2 is the distance from the top of the rail system <NUM> to the lowermost part of the lifting frame <NUM>. The lifting frame <NUM> is suspended from the cantilever section <NUM> via lifting bands <NUM>. The lifting frame <NUM> may comprise gripping devices <NUM> extending from a lower surface thereof for connecting the lifting frame to complementary lifting holes of the storage containers <NUM> thereby rendering possible lifting and lowering of the storage containers <NUM>. In addition, the lifting frame <NUM> may comprise guides <NUM> arranged in the corners of the lower surface of the lifting frame <NUM> to align the gripping devices <NUM> of the lifting frame <NUM> relative the complementary lifting holes on the storage containers <NUM>. In many situations the guides <NUM> or the gripping devices <NUM> may constitute the lowermost part of the lifting frame <NUM> such that the second height h2 is the lowermost part of any of these components. However, according to an embodiment of the invention, the second height h2 of the lowermost part of the lifting frame <NUM>, when the lifting frame <NUM> is docked in its upper position, is always above the first height h1 of the storage container <NUM> positioned on the first container carrying position.

By ensuring that the lowermost part of a docked lifting frame <NUM> of a first container handling vehicle <NUM> can pass over a storage container <NUM> supported on the first container carrying position of a second container handling vehicle <NUM> when the first and second container vehicles <NUM> pass one another on adjacent grid cells <NUM>, the first and second container handling vehicles <NUM> can pass each other while collectively occupying fewer grid cells than required in prior art solutions.

<FIG> is a perspective view of a container handling vehicle <NUM> according to the embodiment of the invention where protective covers have been removed to better illustrate the setup of the components in the lower section <NUM>, the support section <NUM> and the cantilever section <NUM> constituting the body unit <NUM> of the container handling vehicle <NUM>. In the embodiment of <FIG>, the lifting device <NUM> is disclosed as comprising a lifting device motor <NUM>' and at least two lifting shafts <NUM>',<NUM>". The two lifting shafts <NUM>',<NUM>" are arranged in parallel in the cantilever section <NUM>. The lifting bands <NUM> connected to the lifting frame <NUM>, are spooled onto and off the lifting shafts <NUM>',<NUM>", thereby moving the lifting frame <NUM> and any storage container <NUM> carried by the lifting frame <NUM> up and down. Lifting shaft wheels <NUM>',<NUM>" are arranged on each end of the lifting shafts <NUM> and operate together with the lifting shafts <NUM>, respectively. As shown in <FIG>, the lifting device motor <NUM>' is arranged in the lower section <NUM>. The lifting device motor <NUM>' and the two lifting shafts <NUM> are connected to each other via the lifting shaft wheels <NUM>', <NUM>" and an endless flexible force transferring element <NUM>, such as e.g. belt, running via sheaves <NUM> to ensure that the first and second lifting shafts <NUM> rotate simultaneously in the same direction. Any necessary power source (not shown) for supplying power to the lifting device motor <NUM>' may be arranged in the lower section <NUM> in order to obtain a favorable center of gravity with reduced risk of tilting of the container handling vehicle in the event lifting a heavy storage container <NUM> and/ or as a result of too high acceleration/deceleration of the container handling vehicle <NUM>.

The lifting frame <NUM> is shown with guides <NUM> arranged in the corners of the lower surface of the lifting frame <NUM> to align the gripping devices <NUM> of the lifting frame <NUM> relative the complementary lifting holes on the storage containers <NUM>.

Any necessary power source (not shown) for supplying power to the lifting device motor <NUM>" may be arranged in the lower section <NUM> in order to obtain a favorable center of gravity with reduced risk of tilting of the container handling vehicle in the event lifting a heavy storage container <NUM> and/ or as a result of too high acceleration/deceleration of the container handling vehicle <NUM>.

<FIG> is a top view of <FIG>, showing the lower section <NUM>, the support section <NUM> and the cantilever section <NUM>.

<FIG> are examples of different setups providing opposite rotation of the lifting shafts <NUM>',<NUM>". As disclosed in all of the examples of <FIG>, common to all of the force transferring setups, is the presence of a rotatable lifting device motor <NUM>', a first and second lifting shaft wheel <NUM>', <NUM>" whereof each is connected for rotation with the respective lifting shafts <NUM>',<NUM>", at least one sheave <NUM>', <NUM>", a force transferring element <NUM> in the form of an endless belt forming a closed loop and where at least one of sheaves <NUM>',<NUM>" is arranged inside the closed loop. In addition, the first or second lifting shaft wheel <NUM>', <NUM>" is in contact with an inner surface of the endless belt <NUM> and the other of the first or second lifting shaft wheel <NUM>', <NUM>" is in contact with the outer surface of the endless belt <NUM>. This is achieved by arranging one of the first or second lifting shaft wheels <NUM>', <NUM>" inside the closed loop formed by the force transferring element <NUM> and the other of the first or second lifting shaft wheel <NUM>', <NUM>" outside the closed loop formed by the force transferring element <NUM>. The mutual setup of the first and second lifting shaft wheels <NUM>', <NUM>" (e.g., acting on opposite sides of the endless belt), the guide sheaves <NUM>', <NUM>" and the force transferring element <NUM>, are such that the first and second lifting shafts <NUM>', <NUM>" (via first and second lifting shaft wheels <NUM>', <NUM>", respectively) rotate in opposite directions (counter rotates). The first and second lifting shaft wheels <NUM>', <NUM>" are preferably arranged in the same horizontal plane in order to ensure horizontal stability during lifting. The sheave(s) <NUM>', <NUM>" are arranged along the travel of the force transferring element <NUM> at fixed positions such that they provide for a "change" in the travel direction of the force transferring element <NUM>. Each of the sheaves <NUM>', <NUM>" are arranged to lead the force transferring element <NUM> correctly onto the first and second lifting shaft wheel <NUM>', <NUM>" thereby allowing the first and second lifting shaft wheels <NUM>', <NUM>" (and thus the lifting shafts <NUM>', <NUM>") to rotate in opposite directions.

In the example in <FIG>, one sheave <NUM>' is shown.

In the examples of <FIG>, a number of examples of force transferring setups comprising two sheaves <NUM>', <NUM>", are shown. The sheaves <NUM>', <NUM>" are arranged alternating along the path of the force transferring element <NUM> such that the first lifting shaft wheel <NUM>' is followed by a sheave <NUM>', <NUM>" and the second lifting shaft wheel <NUM>" is followed by a sheave <NUM>', <NUM>" in both directions of travel of the force transferring element <NUM>.

In the examples of <FIG>, there are disclosed examples comprising a tightening wheel <NUM> for tensioning of the force transferring element <NUM>. The tightening wheel <NUM> may for example be an eccentric tensioning mechanism comprising a rotatable sheave with an axle that can be adjusted within an opening in a fixed bracket. The location of the tightening wheel <NUM> along the path of the force transferring element <NUM> is preferably at a location where the path length of the force transferring element <NUM> can be affected (i.e. the path of the force transferring element can be shortened or prolonged in order to further tension or reduce tension in the force transferring element). The tightening wheel <NUM> can be arranged inside (<FIG>) or outside (<FIG>) the closed loop formed by the force transferring element <NUM>.

In the examples in <FIG>, a dedicated tensioning mechanism such as a tightening wheel is not shown; however, if a tensioning mechanism is required, one of the sheaves <NUM>' or <NUM>" may be a tensioning mechanism and can be replaced by a tightening wheel <NUM>.

<FIG> is an example of another setup of the lifting device <NUM>, where, in addition to the lifting shafts <NUM> and the lifting bands spoolable onto and off the lifting shafts <NUM>', <NUM>", also the lifting device motor <NUM>" is arranged in the cantilever section <NUM> of the body unit <NUM>. The lifting device motor(s) <NUM>" in <FIG> is a brushless DC motor encircling one of the lifting shafts <NUM>', <NUM>". Synchronous operation of the lifting shafts <NUM>', <NUM>" can be obtained by a synchronization element such as a force transferring element as disclosed in Figs. 5A-5E and 6A-<NUM> in <CIT> (Applicant: Autostore Technology AS).

<FIG> is a simplified side-view of a container handling vehicle <NUM> according to an embodiment of the invention supporting one storage container <NUM> on a first container carrying position <NUM> and one storage container <NUM> by the lifting device <NUM>, the container handling vehicle <NUM> comprising a wheel base unit <NUM> and a body unit, where the body unit comprises a lower section <NUM>, a support section <NUM> and a cantilever section <NUM>. The components of the container handling vehicle in <FIG> are similar to the container handling vehicle in <FIG>. The first container carrying position <NUM> is preferably recessed to provide sideways support for a storage container <NUM> positioned on the first container carrying position <NUM>.

<FIG> show step-by-step an examplary method of transferring a storage container <NUM> between a first and a second container handling vehicle <NUM> operating on an automated storage and retrieval system <NUM> comprising a two-dimensional rail system <NUM>. Referring to <FIG>, a first container handling vehicle <NUM> (i.e. the vehicle to the right in the figure not carrying a storage container <NUM>) is positioned in a distance from the second container handling vehicle <NUM> (i.e. the vehicle to the left in the figure carrying a storage container <NUM> in the lifting device and carrying a storage container <NUM> on the first container carrying position <NUM>). The first container handling vehicle <NUM> and the second container handling vehicle <NUM> operate in neighboring rows on the rail system <NUM>.

In <FIG> the first and second container handling vehicles <NUM> have moved closer to each other compared to the situation in <FIG> and the lifting device <NUM> of the first container handling vehicle <NUM> is almost above the upper surface/first container carrying position <NUM> of the lower section <NUM> of the second container handling vehicle <NUM>.

In <FIG> the first and second container handling vehicles <NUM> have positioned themselves in neighboring grid cells <NUM> such that the lifting device <NUM> of the first container handling vehicle <NUM> is directly above the upper surface/first container carrying position <NUM> of the lower section <NUM> of the second container handling vehicle <NUM>.

In <FIG> the lifting device <NUM> of the first container handling vehicle <NUM> has been lowered down to lift the storage container <NUM> positioned on the first container carrying position <NUM> on the second container handling vehicle <NUM> and lifted the storage container <NUM> off the first container carrying position <NUM>. The transfer of the storage container <NUM> is now complete.

Referring to <FIG>, the method of transferring the storage container may comprise the steps of:.

The get_bin command may include a parameter defining a height of the storage container <NUM> to be transferred such that the lifting device <NUM> of the master vehicle is lowered to a position equal to an uppermost part of the storage container positioned on the first container carrying position.

The step of setting the other container handling vehicle <NUM> as a slave vehicle may comprise the step of sending a synchronize_to_master command to the slave vehicle, such that the slave vehicle moves with and follows the master vehicle. This allows for transferring the storage container <NUM> between the upper surface of the lower section <NUM> of the second container handling vehicle <NUM> and the lifting device <NUM> of the first container handling vehicle <NUM> in motion. The slave vehicle may optionally send a message to the main control system when synchronization has been obtained. Alternatively, the main control system may determine that synchronization has been obtained based on positional information of the slave vehicle and the master vehicle. Synchronization has been obtained when the slave vehicle moves with and follows the master vehicle.

The master vehicle may send movement data, such as speed, acceleration, and position data to the slave vehicle. The slave vehicle may use the movement data to synchronize its own movements to the received movement data. The master vehicle may send the movement data via the main control system. The master vehicle may alternatively, or additionally send the movement data directly to the slave vehicle using local communication between the master vehicle and the slave vehicle. The local communication may be any suitable means of local wireless communication, such as near field communication (NFC) or infrared (IR).

Synchronized movement of the slave vehicle and the master vehicle may include a train-like synchronization where the slave vehicle follows behind the master vehicle, or the synchronized movement may include a parallel synchronization where the slave vehicle moves with the master vehicle side by side.

The automated storage and retrieval system may comprise a positioning system using multilateration techniques, such as a Time of Flight (TOF) measurement system, for determining the position of both the master vehicle and the slave vehicle. The main control system continuously receives position data from the positioning system of a position of the first container handling vehicle and position data of a position of the second container handling vehicle. The main control system may use the position data to instruct slave vehicle to move with and follow the master vehicle within a predetermined separation from the master vehicle. The movement of the master vehicle and the slave vehicle is thereby synchronized such that the step of transferring the storage container <NUM> between the upper surface of the lower section <NUM> of the second container handling vehicle <NUM> and the lifting device <NUM> of the first container handling vehicle <NUM> may be performed in motion.

The container handling vehicles may be arranged with sensors that can detect the position of the container handling vehicles on the rail system, and/or proximity sensors that detects the distance to nearby container handling vehicles. The main control system may instruct the slave vehicle to move with and follow the master vehicle within a predetermined separation from the master vehicle based on received distance data from the proximity sensor of the slave vehicle. The movement of the master vehicle and the slave vehicle is thereby synchronized such that the step of transferring the storage container <NUM> between the upper surface of the lower section <NUM> of the second container handling vehicle <NUM> and the lifting device <NUM> of the first container handling vehicle <NUM> may be performed in motion.

The container handling vehicles may be adapted to move together in physical contact with one another. The main control system may instruct the slave vehicle to move with and follow the master vehicle by first moving into physical contact of the master vehicle, and after contact continue to apply a push force on the master vehicle to maintain physical contact. The movement of the master vehicle and the slave vehicle is thereby synchronized such that the step of transferring the storage container <NUM> between the upper surface of the lower section <NUM> of the second container handling vehicle <NUM> and the lifting device <NUM> of the first container handling vehicle <NUM> may be performed in motion.

<FIG> show examples of a container handling vehicle <NUM> according to an embodiment of the invention with a conveyor <NUM> on the first container carrying position <NUM> adapted to transfer the storage container <NUM> backwards onto another container handling vehicle or to an external conveyor. through any of the short sides of the container handling vehicle <NUM>. The conveyor <NUM> could also have been oriented <NUM> degrees relative the embodiment of <FIG> such that storage containers <NUM> could be transferred directly backwards onto another container handling vehicle or to an external conveyor (see <FIG> shows a situation when not carrying a storage container on the first container carrying position <NUM>, while <FIG> shows a situation with a storage container <NUM> on the first container carrying position <NUM>, and <FIG> shows a possible transfer of the storage container <NUM> from the conveyor <NUM> on the first container carrying position <NUM> and to an external conveyor <NUM>. An upper surface of the external conveyor <NUM> is preferably arranged at the substantially same height as an upper surface of the conveyor <NUM> on first container carrier position <NUM>.

Referring to <FIG> and <FIG> the lower section <NUM> has an upper surface <NUM> which is recessed with respect to a pair of support webs <NUM>, wherein the upper surface <NUM> provides the first container carrying position <NUM> for carrying a storage container <NUM>. The support section <NUM> extends vertically from the pair of support webs <NUM> of the lower section <NUM>, the support section <NUM> having a footprint with a horizontal extent which is smaller than the footprint of the lower section <NUM>.

<FIG> shows an example of a container handling vehicle <NUM> according to an embodiment of the invention comprising an upper surface <NUM> providing a first container carrying position <NUM> and a support surface <NUM> providing a second container carrying position <NUM>. The container handling vehicle <NUM> of <FIG> comprises similar components as the container handling vehicle of <FIG> and <FIG>, which will not be repeated herein. However, the container handling vehicle <NUM> in <FIG> additionally comprises the second container carrying position <NUM>. The second container carrying position <NUM> is disclosed as being arranged above the first container carrying position <NUM>. Preferably, the first and second container carrying positions <NUM>, <NUM> form the same vertical projection on the underlying rail system <NUM>.

<FIG> shows the second container carrying position of <FIG> in a retracted position via a pivot connection <NUM> such that in the retracted position the second container carrier position <NUM> is directed upwards. The arrow A shows the direction of movement from a horizontal extended position (in <FIG>) and a vertical retracted position in <FIG>. The pivot connection <NUM> shows the axle of rotation of the second container carrier <NUM>.

<FIG> shows another example of a possible extended position of the second container carrier position <NUM>. In <FIG> the second container carrier position <NUM> is in the extended horizontal position where it can receive a storage container (not shown).

<FIG> shows the example of <FIG> where the second container carrier position <NUM> has been pivoted <NUM> degrees and rests upside down on the cantilever section <NUM> of the container handing vehicle <NUM> when in the retraced position. The second container carrying position <NUM> has been pivoted from the retracted position to the extended position around the pivot connection arrangement <NUM> as shown with the arrow A.

<FIG> show yet another example of the second container carrier position <NUM>, where, in <FIG> the second container carrier position <NUM> is in the extended position directly above the first container carrying position <NUM>, and in <FIG>, the second container carrying position is moved linearly (as indicated with arrow A) to a retracted position by means of a linear movement arrangement (not shown).

Thus, referring to <FIG> and <FIG>, in order to obtain access to a storage container <NUM> positioned on the first container carrying position <NUM>, the second container carrying position <NUM> is preferably movable between:.

If using a pivot connection (see <FIG>), the pivot connection <NUM> can be arranged such that:.

If using a linear movement arrangement (see <FIG>), the linear movement arrangement can be arranged such that:.

In the preceding description, various aspects of an automated storage and retrieval system according to the invention have been described with reference to the illustrative embodiment. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the system, which are apparent to persons skilled in the art, are deemed to lie within the scope of the present invention as defined by the following claims.

Claim 1:
A container handling vehicle (<NUM>) for operation on a two-dimensional rail system (<NUM>) comprising a first set of parallel rails (<NUM>) arranged to guide movement of container handling vehicles (<NUM>) in a first direction (X) across the top of a frame structure (<NUM>), and a second set of parallel rails (<NUM>) arranged perpendicular to the first set of rails (<NUM>) to guide movement of the container handling vehicles (<NUM>) in a second direction (Y) which is perpendicular to the first direction, the first and second sets of parallel rails (<NUM>,<NUM>) dividing the rail system (<NUM>) into a plurality of grid cells (<NUM>), wherein the container handling vehicle (<NUM>) comprises:
- a wheel base unit (<NUM>) comprising first and second sets of wheels (32a, 32b) for guiding the container handling vehicle (<NUM>) along the rail system (<NUM>) in the first and second directions (X, Y) respectively, wherein the first and second sets of wheels (32a, 32b) form outer peripheries of the wheel base unit (<NUM>);
- a body unit (<NUM>) comprising:
a lower section (<NUM>) which is provided on the wheel base unit (<NUM>), the lower section (<NUM>) having a footprint with a horizontal extent which is equal to or less than the wheel base unit (<NUM>), the lower section (<NUM>) having an upper surface, the upper surface (<NUM>) providing a first container carrying position (<NUM>) for carrying a storage container (<NUM>);
a support section (<NUM>) extending vertically from the lower section (<NUM>), the support section (<NUM>) having a footprint with a horizontal extent which is smaller than the footprint of the lower section (<NUM>); and
a cantilever section (<NUM>) extending horizontally from the support section (<NUM>) beyond the footprint of the lower section (<NUM>); and
- a lifting device (<NUM>) comprising a lifting frame (<NUM>) that is suspended from the cantilever section (<NUM>).