Patent Publication Number: US-2023137545-A1

Title: Delivery vehicle, system and method for moving storage containers between a first conveyor on the delivery vehicle and an external conveyor

Description:
FIELD OF THE INVENTION 
     The invention relates to the field of automated storage and retrieval systems. In particular, the invention relates to a delivery vehicle, a system and method for moving storage containers between a first conveyor on the delivery vehicle and an external second conveyor. 
     BACKGROUND AND PRIOR ART 
       FIG.  1 A  discloses a typical prior art automated storage and retrieval system  1  with a framework structure  100  and  FIGS.  2  and  3    discloses two different prior art container handling vehicles  201 , 301  suitable for operating on such a system  1 . 
     The framework structure  100  comprises upright members  102 , horizontal members  103  and a storage volume comprising storage columns  105  arranged in rows between the upright members  102  and the horizontal members  103 . In these storage columns  105  storage containers  106 , also known as bins, are stacked one on top of one another to form stacks  107 . The members  102 ,  103  may typically be made of metal, e.g. extruded aluminum profiles. 
     The framework structure  100  of the automated storage and retrieval system  1  comprises a rail system  108  arranged across the top of framework structure  100 , on which rail system  108  a plurality of container handling vehicles  201 , 301  are operated to raise storage containers  106  from, and lower storage containers  106  into, the storage columns  105 , and also to transport the storage containers  106  above the storage columns  105 . The rail system  108  comprises a first set of parallel rails  110  arranged to guide movement of the container handling vehicles  201 , 301  in a first direction X across the top of the frame structure  100 , and a second set of parallel rails  111  arranged perpendicular to the first set of rails  110  to guide movement of the container handling vehicles  201 , 301  in a second direction Y which is perpendicular to the first direction X. Containers  106  stored in the columns  105  are accessed by the container handling vehicles through access openings  112  in the rail system  108 . The container handling vehicles  201 , 301  can move laterally above the storage columns  105 , i.e. in a plane which is parallel to the horizontal X-Y plane. 
     The upright members  102  of the framework structure  100  may be used to guide the storage containers during raising of the containers out from and lowering of the containers into the columns  105 . The stacks  107  of containers  106  are typically self-supportive. 
     Each prior art container handling vehicle  201 , 301  comprises a vehicle body  201   a , 301   a , and first and second sets of wheels  201   b , 301   b , 201   c , 301   c  which enable the lateral movement of the container handling vehicles  201 , 301  in the X direction and in the Y direction, respectively. In  FIGS.  2  and  3    two wheels in each set are fully visible. The first set of wheels  201   b , 301   b  is arranged to engage with two adjacent rails of the first set  110  of rails, and the second set of wheels  201   c , 301   c  is arranged to engage with two adjacent rails of the second set  111  of rails. At least one of set wheels  201   b , 301   b , 201   c , 301   c  can be lifted and lowered, so that the first set of wheels  201   b , 301   b  and/or the second set of wheels  201   c , 301   c  can be engaged with the respective set of rails  110 ,  111  at any one time. 
     Each prior art container handling vehicle  201 , 301  also comprises a lifting device (not shown) for vertical transportation of storage containers  106 , e.g. raising a storage container  106  from, and lowering a storage container  106  into, a storage column  105 . The lifting device comprises one or more gripping/engaging devices which are adapted to engage a storage container  106 , and which gripping/engaging devices can be lowered from the vehicle  201 , 301  so that the position of the gripping/engaging devices with respect to the vehicle  201 , 301  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  301  is shown in in  FIG.  3    and is indicated with reference number  304 . The gripping device of the container handling device  201  is located within the vehicle body  301   a  in  FIG.  2   . 
     Conventionally, and also for the purpose of this application, Z=1 identifies the uppermost layer of storage containers, i.e. the layer immediately below the rail system  108 , Z=2 the second layer below the rail system  108 , Z=3 the third layer etc. In the exemplary prior art disclosed in  FIG.  1 A , Z=8 identifies the lowermost, bottom layer of storage containers. Similarly, X=1 . . . n and Y=1 . . . n identifies the position of each storage column  105  in the horizontal plane. Consequently, as an example, and using the Cartesian coordinate system X, Y, Z indicated in  FIG.  1 A , the storage container identified as  106 ′ in  FIG.  1 A  can be said to occupy storage position X=10, Y=2, Z=3. The container handling vehicles  201 , 301  can be said to travel in layer Z=0, and each storage column  105  can be identified by its X and Y coordinates. 
     The storage volume of the framework structure  100  has often been referred to as a grid  104 , 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. 
     Each prior art container handling vehicle  201 , 301  comprises a storage compartment or space for receiving and stowing a storage container  106  when transporting the storage container  106  across the rail system  108 . The storage space may comprise a cavity arranged centrally within the vehicle body  201   a  as shown in  FIG.  2    and as described in e.g. WO2015/193278A1, the contents of which are incorporated herein by reference. 
       FIG.  3    shows an alternative configuration of a container handling vehicle  301  with a cantilever construction. Such a vehicle is described in detail in e.g. NO317366, the contents of which are also incorporated herein by reference. 
     The central cavity container handling vehicles  201  shown in  FIG.  2    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  105 , e.g. as is described in WO2015/193278A1, the contents of which are incorporated herein by reference. The term ‘lateral’ used herein may mean ‘horizontal’. 
     Alternatively, the central cavity container handling vehicles  101  may have a footprint which is larger than the lateral area defined by a storage column  105 , e.g. as is disclosed in WO2014/090684A1. 
     The rail system  108  typically comprises rails with grooves into which the wheels of the vehicles are inserted. Alternatively, the rails may comprise upwardly protruding elements, where the wheels of the vehicles comprise flanges to prevent derailing. These grooves and upwardly protruding elements are collectively known as tracks. Each rail may comprise one track, or each rail may comprise two parallel tracks (so-called “double tracks” which is described in relation to  FIGS.  1 B- 1 D  below). 
     WO2018146304, the contents of which are incorporated herein by reference, illustrates a typical configuration of rail system  108  comprising rails and parallel tracks in both X and Y directions. 
     In the framework structure  100 , a majority of the columns  105  are storage columns  105 , i.e. columns  105  where storage containers  106  are stored in stacks  107 . However, some columns  105  may have other purposes. In  FIG.  1 A , columns  119  and  120  are such special-purpose columns used by the container handling vehicles  201 , 301  to drop off and/or pick up storage containers  106  so that they can be transported to an access station (not shown) where the storage containers  106  can be accessed from outside of the framework structure  100  or transferred out of or into the framework structure  100 . 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’  119 , 120 . The transportation to the access station may be in any direction, that is horizontal, tilted and/or vertical. For example, the storage containers  106  may be placed in a random or dedicated column  105  within the framework structure  100 , then picked up by any container handling vehicle and transported to a port column  119 , 120  for further transportation to an access station. Note that the term ‘tilted’ means transportation of storage containers  106  having a general transportation orientation somewhere between horizontal and vertical. 
     In  FIG.  1 A , the first port column  119  may for example be a dedicated drop-off port column where the container handling vehicles  201 , 301  can drop off storage containers  106  to be transported to an access or a transfer station, and the second port column  120  may be a dedicated pick-up port column where the container handling vehicles  201 , 301  can pick up storage containers  106  that have been transported from an access or a transfer station. 
     The access station may typically be a picking or a stocking station where product items are removed from or positioned into the storage containers  106 . In a picking or a stocking station, the storage containers  106  are normally not removed from the automated storage and retrieval system  1 , but are returned into the framework structure  100  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. 
     A conveyor system comprising conveyors is normally employed to transport the storage containers between the port columns  119 , 120  and the access station. 
     If the port columns  119 , 120  and the access station are located at different levels, the conveyor system may comprise a lift device with a vertical component for transporting the storage containers  106  vertically between the port column  119 , 120  and the access station. 
     The conveyor system may be arranged to transfer storage containers  106  between different framework structures, e.g. as is described in WO2014/075937A1, the contents of which are incorporated herein by reference. 
     When a storage container  106  stored in one of the columns  105  disclosed in  FIG.  1 A  is to be accessed, one of the container handling vehicles  201 , 301  is instructed to retrieve the target storage container  106  from its position and transport it to the drop-off port column  119 . This operation involves moving the container handling vehicle  201 , 301  to a location above the storage column  105  in which the target storage container  106  is positioned, retrieving the storage container  106  from the storage column  105  using the container handling vehicle&#39;s  201 , 301  lifting device (not shown), and transporting the storage container  106  to the drop-off port column  119 . If the target storage container  106  is located deep within a stack  107 , i.e. with one or a plurality of other storage containers  106  positioned above the target storage container  106 , the operation also involves temporarily moving the above-positioned storage containers prior to lifting the target storage container  106  from the storage column  105 . This step, which is sometimes referred to as “digging” within the art, may be performed with the same container handling vehicle that is subsequently used for transporting the target storage container to the drop-off port column  119 , or with one or a plurality of other cooperating container handling vehicles. Alternatively, or in addition, the automated storage and retrieval system  1  may have container handling vehicles specifically dedicated to the task of temporarily removing storage containers from a storage column  105 . Once the target storage container  106  has been removed from the storage column  105 , the temporarily removed storage containers can be repositioned into the original storage column  105 . However, the removed storage containers may alternatively be relocated to other storage columns. 
     When a storage container  106  is to be stored in one of the columns  105 , one of the container handling vehicles  201 , 301  is instructed to pick up the storage container  106  from the pick-up port column  120  and transport it to a location above the storage column  105  where it is to be stored. After any storage containers positioned at or above the target position within the storage column stack  107  have been removed, the container handling vehicle  201 , 301  positions the storage container  106  at the desired position. The removed storage containers may then be lowered back into the storage column  105 , or relocated to other storage columns. 
     For monitoring and controlling the automated storage and retrieval system  1 , e.g. monitoring and controlling the location of respective storage containers  106  within the framework structure  100 , the content of each storage container  106 ; and the movement of the container handling vehicles  201 , 301  so that a desired storage container  106  can be delivered to the desired location at the desired time without the container handling vehicles  201 , 301  colliding with each other, the automated storage and retrieval system  1  comprises a control system  500  which typically is computerized and which typically comprises a database for keeping track of the storage containers  106 . 
     It is therefore an objective of the invention to provide an improved cost-efficient and less complex system for transferring storage containers between a delivery vehicle and an external conveyor. 
     SUMMARY OF THE INVENTION 
     The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention 
     It is described a delivery vehicle for operation on a two-dimensional rail system with rails extending in a first direction and a second direction, wherein the second direction is perpendicular to the first direction, the delivery vehicle comprising:
         a vehicle body;   two sets of wheels connected to the vehicle body for engagement with the underlying rail system and for moving the delivery vehicle in the first and second directions;   a container carrier for supporting a container from below, wherein the container carrier comprises a first conveyor;   a conveyor drive shaft for driving the first conveyor;   at least one drive coupling comprising a connection interface accessible from an outer side portion of the vehicle body, wherein the drive coupling is rotatably connected to a motor drive shaft such that when the motor drive shaft is rotated the drive coupling and the connection interface are rotated.       

     In this way, the delivery vehicle can drive a remote second conveyor via the drive coupling and an associated complementary connection interface. This reduces the overall cost of a conveyor system, because normally conveyors require specific equipment, such as a dedicated motor to be able to rotate the conveyor. 
     The delivery vehicle may further comprise a motor connected to the motor drive shaft, wherein the motor drive shaft is rotatably connected to the conveyor drive shaft. 
     The connection interface can be positioned within a recess on the delivery vehicle. In this way the connection interface may not protrude beyond the cross-sectional area of the delivery vehicle when looking in plan view of the delivery vehicle, such that two delivery vehicles each comprising a connection interface on passing sides can pass one another on adjacent tracks of a rail of the rail system without coming into contact with one another. 
     The complementary connection interface on the remote second conveyor may protrude from a remainder of the conveyor in order for its connection interface to engage the connection interface of the delivery vehicle within the recess. 
     It is further described an assembly of a delivery vehicle as described above coupled with a remote second conveyor, the connection interface of the delivery vehicle coupled with a complementary connection interface of the second conveyor to deliver torque from the delivery vehicle&#39;s drive coupling to a drive shaft of the second conveyor. The remote second conveyor&#39;s sole source of power may be from the torque supplied by the delivery vehicle via the coupled connection interfaces. In this way the remote conveyor may not require a power supply nor any electrical devices. 
     Preferably, the connection interface between the first and second conveyors preferably transmits rotational movement with a 1:1 ratio. In general, a 1:1 ratio for all types of connection interface may be advantageous in order to match the speeds of the first conveyor with the second conveyor. 
     It is further described a delivery vehicle for operation on a two-dimensional rail system with rails extending in a first direction and a second direction,
         a container carrier for supporting a container from below, wherein the container carrier comprises a conveyor;   a conveyor drive shaft for rotating the conveyor;   at least one drive coupling comprising a connection interface accessible from on an outer side portion of the vehicle body, wherein the drive coupling is rotatably connected to a motor drive shaft such that when the motor drive shaft is rotated the drive coupling is rotated.       

     In other words, in this embodiment, the drive coupling and connection interface on at least one side of the vehicle body may serve as a torque or power output on at least one side of the vehicle body. This torque output is used to drive the external or remote second conveyors. 
     The vehicle body may comprise all necessary components in order to move the delivery vehicle, such as one or more motors for driving the wheels and for track shift switching between movement in the first direction and the second direction on the underlying rail system. In addition, the delivery vehicle may comprise one or more motors for driving the conveyor. Furthermore, the delivery vehicle may comprise means for communicating with a main control system, such that the main control system can instruct the delivery vehicle to move to specific parts of the grid as well as receiving information from the delivery vehicle. 
     The first conveyor may be arranged for horizontal movement of a container supported by the first conveyor. 
     The container carrier may comprise a conveyor arranged to convey the container on and off the container carrier in a horizontal direction. 
     The first conveyor can handle storage containers of different shapes and sizes, such as e.g. AutoStore bin and other boxes of the same size, or larger or smaller size than the standard Autostore bin. 
     The container may be a storage container, a KLT box, a packing box, etc. Thus, as used herein, the term “storage container or container” is related to any container suitable for holding one or more items. The “container” may be made of any material suitable for the purpose of holding at least one item, such as plastic, metal, wood, paper, etc. 
     A KLT box is an industrial stacking container conforming to the VDA 4500 standard. The most common sizes are 600 mm×400 mm and 400 mm×300 mm, meaning that these containers stacked upon each other will fill a Euro-pallet measuring 1200 mm×800 mm. These containers may be stacked and are manufactured typically in grey polypropylene or another thermoplastic by injection molding. 
     The delivery vehicles may comprise one or more sensors to detect that the storage container has moved far enough onto the first conveyor before the delivery vehicle can drive. The same sensor(s) or additional sensor(s) can be provided to detect whether the storage container has moved too far onto the first conveyor such that there is a risk the storage container might come off the opposite end of the first conveyor. 
     A rotational axis of the connection interface may be perpendicular to a rotational axis of the conveyor drive shaft. The rotational axis of the motor drive shaft and the connection interface may in the same plane. 
     The delivery vehicle may further comprise an angled transmission for transferring rotational motion about the motor drive shaft to rotational motion about the connection interface. Angled transmission may be a bevel gear transmission. Preferably, the bevel gear transmission is mitre gears. Mitre gears are a type of bevel gears that have equal numbers of teeth. The shafts are positioned at right angles from each other, and the gears have matching pitch surfaces and angles, with a conically shaped pitch surface. 
     Mitre gears may be useful for transmitting rotational motion at a 90 degrees angle with a 1:1 ratio. 
     The drive coupling of the delivery vehicle may comprise:
         a first connection shaft parallel to the motor drive shaft,   a second connection shaft rotatably connected to the first connection shaft via the angled transmission, and wherein the connection interface may be connected on the second connection shaft.       

     The connection interface may comprise a cog-wheel mounted on the conveyor drive shaft ( 42 ) for transferring rotational movement from the first conveyor to an external cog-wheel connected to a second conveyor drive shaft ( 74 ) of a second conveyor. In order to ensure that the first and second conveyors rotate in the same direction an idler gear system connected to the external cog-wheel may be used. 
     The motor drive shaft and the conveyor drive shaft may be parallel. 
     The motor drive shaft and the conveyor drive shaft may have a common axis of rotation. 
     The delivery vehicle may comprise two connection interfaces, each of the connection interfaces being arranged on an opposite outer side portion of the vehicle body for operating second conveyors arranged on opposite ends of the delivery vehicle. 
     The connection interface may comprise an intermediate roller arranged parallel to the first conveyor, and which rotates together with the first conveyor. When the delivery vehicle is positioned next to a second conveyor, both the first conveyor and the second conveyor are in contact with the intermediate roller, and rotational movement is transferred from the first conveyor, via the intermediate roller, to the second conveyor. The intermediate roller ensures that the first and second conveyors rotate in the same direction. 
     The first conveyor and the intermediate roller can be mechanically linked or they may be in frictional contact. The intermediate roller and the second conveyor may, when the delivery vehicle is positioned next to the second conveyor be in frictional contact. The second conveyor then forms a complementary connection interface. 
     The first conveyor on the delivery vehicle may comprise a plurality of parallel oriented rolls having a common longitudinal direction perpendicular to one or more side walls. In this way the rolls allow one or more containers to be shifted into or off the first conveyor while being guided by the side walls. The first conveyor may comprise rolls with or without integrated motor(s) mounted between supports for respective ends of the rolls (such as parallel railings). The rolls allow the storage container to be moved onto or out of the first conveyor. In addition, the rolls provide support from below for the storage container while situated on the first conveyor of the delivery vehicle. 
     The first conveyor may be conveyor, rollers, belt, balls, rods, a chain drive or any similar means adapted for the easy moving of the storage container from the first conveyor to the second conveyor, or in a counter direction from the second conveyor to the first conveyor. 
     The simple setup of the second conveyor, i.e. not need for software nor power to operate the second conveyor, provides for modularity in terms of where to arrange the second conveyors around the periphery of the rail system. 
     It is further described a system for horizontal movement of storage containers between a first conveyor and a second conveyor, wherein the system comprises:
         a two-dimensional rail system with rails extending in a first direction and a second direction, wherein the second direction is perpendicular to the first direction,   a delivery vehicle comprising a vehicle body and two sets of wheels connected to the vehicle body for engagement with the underlying rail system and for moving the delivery vehicle in the first and second directions, wherein the delivery vehicle comprises a first conveyor for supporting a storage container from below;   a second conveyor separate from the first conveyor;   a motor assembly for driving the first and/or second conveyor;   at least one drive coupling comprising a connection interface accessible from an outer side portion of the vehicle body for transferring rotational movement between the first conveyor and the second conveyor.       

     A connection interface of the second conveyor may comprise a complementary connection interface for engagement with the connection interface of the delivery vehicle such that when the first and second conveyors are in contact with each other a container can be transferred between the first and second conveyors. 
     The delivery vehicle may comprise the motor assembly for driving the first conveyor. The motor assembly comprises any necessary motors or gearing to rotate the first conveyor and the drive coupling (and the associated connection interface), such as a motor and a motor drive shaft and a belt or similar for rotating a conveyor drive shaft of the first conveyor. 
     In an aspect, the second conveyor is non-motorized. 
     In another aspect, the first conveyor is non-motorized and the motor assembly is connected to the second conveyor. The motor assembly is then arranged in connection with the second conveyor and may comprise necessary motors or gearing to rotate the second conveyor and complementary connection interface, such as a motor, a motor drive shaft and a belt or similar for rotating a conveyor drive shaft of the first conveyor. 
     In an aspect of the system, the delivery vehicle can be a delivery vehicle as described above. 
     The complementary connection interface may comprise an intermediate roller associated with the second conveyor, and which rotates together with the second conveyor, and wherein the intermediate roller is arranged such that, when the first conveyor on the delivery vehicle is in contact with the intermediate roller, rotational movement of the first conveyor is transferred to the second conveyor via the intermediate roller. The rotational movement is preferably transferred from the intermediate roller to the first conveyor by frictional contact. 
     When the delivery vehicle comes into contact with the external conveyor, it can lower itself down into contact with the intermediate roller connected to the external conveyor. This ensures a good contact and sufficient friction, and thus power, so that the rotational movement of the first conveyor on the delivery vehicle can be transferred to the rotational movement of the external second conveyor even with heavy boxes. 
     Furthermore, in addition, if the delivery vehicle is positioned directly above a grid cell/access opening, all of the wheels may be lowered to contact the rail system during movement of storage containers between the first and second conveyors. This will give a more stable delivery vehicle during the transfer of storage containers between the first and second conveyors. 
     In another aspect of the system, the connection interface and complementary connection interface comprise a cog-wheel associated with the first and second conveyors arranged such that when a cog-wheel associated with the first conveyor is in contact with a cog-wheel associated the second conveyor, rotational movement of the first conveyor is transferred to the second conveyor via the cog-wheels, or vice versa. The system may further comprise an idler gear system for ensuring that the first and second conveyors rotate in the same direction. 
     The connection interface can be positioned within a recess on the delivery vehicle such that the connection interface connects to a protruding torque output such as a complementary connection interface on an external second conveyor. 
     The motor driving the first conveyor may operate reversibly for moving the first conveyor (and any connected second conveyor, in two directions). 
     The second conveyor may be rollers, belt conveyor, balls, rods, a chain drive or any similar means adapted for the easy moving of the storage container between the first and second conveyors. 
     The second conveyor may form a stand-alone unit or it may be arranged side-by-side with other second conveyors forming larger units with two or more second conveyors. 
     The delivery vehicle is arranged for delivering/receiving the container to/from an external second conveyor. The second conveyor may be arranged for transport of the container between the first container and an access station or access point arranged on an opposite side of the second conveyor. In this example, the second conveyor and the access station may form one common conveyor or they may be separate conveyors mechanically linked to move together. In either case, the second conveyor and the access station move in tandem in the same direction, i.e. synchronously. The motor operating the first conveyor may have sufficient power to operate the first conveyor, the second conveyor and any conveyor of the access station. 
     An upper surface of the second conveyor is preferably at same height as an upper surface of the first conveyor that the container is carried on. This allows the container to easily enter or exit the second conveyor from the first conveyor. 
     The container may be transported on the rollers to/from the access station. That means that the drive motor drives the rollers for transporting the container to the access station, and after an item(s) in the container has been handled, the motor is reversed for moving the first and second conveyors, and thus the storage container, in the opposite direction, away from the access station and towards the first conveyor on the delivery vehicle. 
     The access station may comprise walls or enclosure panels arranged about a perimeter of the access station and at least a section of the second conveyor. 
     The delivery vehicle may be arranged to deliver a first container to the second conveyor and move to another second conveyor to receive a second container which has been handled at an access station. 
     In certain situations, if the delivery vehicle comprises openings in both opposite ends, the delivery vehicle can replace a standard conveyor in that the storage container can enter the delivery vehicle from one side, then the delivery vehicle can move a certain distance, before the storage container exits the delivery vehicle on the other side. 
     The second conveyor, i.e. the external conveyor, can be e.g.:
         a picking station from which a human or robotic operator may pick on or more items from the storage container, or   it can form a buffer in a lower end of a port column such that storage containers can be lowered onto, or retrieved from, the second conveyor either by container handling vehicles operating in a plane above the second conveyor or by delivery vehicles with a first conveyor in the same plane as the second conveyor. Possibly, two or more storage containers can be placed on top of one another on the second conveyor.       

     The second conveyors may be arranged at different levels, where one or more lifts can be used to transfer delivery vehicles between the different levels. Such delivery vehicle lifts are known to the skilled person, for example as disclosed in document WO2019238639A1 (applicant: Autostore Technology AS), which content is incorporated herein. 
     It is further described a method of horizontal movement of storage containers between a first conveyor and a second conveyor in an automated storage and retrieval system, wherein the system comprises:
         a two-dimensional rail system with rails extending in a first direction and a second direction, wherein the second direction is perpendicular to the first direction,   a delivery vehicle comprising a vehicle body and two sets of wheels connected to the vehicle body for engagement with the underlying rail system and for moving the delivery vehicle in the first and second directions, wherein the delivery vehicle comprises a first conveyor for supporting a storage container from below;   a second conveyor separate from the first conveyor;   a motor assembly for driving the first or second conveyor; wherein the method comprises the steps of:   instructing the delivery vehicle to enter a position next to the second conveyor such that a connection interface of the delivery vehicle is in contact with a complementary connection interface of the second conveyor which represents a position where an upper surface of the first conveyor is in the same plane or substantially in the same plane as an upper surface of the second conveyor, wherein the connection interface of the delivery vehicle is configured for engagement with the complementary connection interface of the second conveyor;   operating the motor assembly to drive the first or second conveyor, wherein rotational movement is transferred between the first and second conveyors, thereby moving the storage container between the upper surface of the first conveyor and the second conveyor.       

     In an aspect of the method, the motor assembly can be connected to the first conveyor of the delivery vehicle, such that, upon rotation of the first conveyor, the second conveyor is rotated via the connection interface and the complementary connection interface. 
     The motor assembly may be connected to the second conveyor, such that, upon rotation of the second conveyor, the first conveyor is rotated via the connection interface and the complementary connection interface. 
     The following drawings are appended to facilitate the understanding of the invention. The drawings show embodiments of the invention, which will now be described by way of example only, where: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a perspective view of a framework structure of a prior art automated storage and retrieval system; 
         FIGS.  1 B-D  is a top view of a container handling vehicle rail system, where  FIG.  1 B  shows a single rail system,  FIG.  1 C  shows a double rail system and  FIG.  1 D  shows a double rail system with the width and length of a container handling vehicle grid cell indicated 
         FIG.  2    is a perspective view of a prior art container handling vehicle having a centrally arranged cavity for carrying storage containers therein; 
         FIG.  3 A  is a perspective view of a prior art container handling vehicle having a cantilever for carrying storage containers underneath; 
         FIGS.  3 B and  3 C  are perspective views of a prior art automated storage and retrieval system, where  FIG.  3 B  shows a part of the system having a delivery rail system with container delivery vehicles operating below the rail system of container handling vehicles and  FIG.  3 C  shows an example of a container delivery vehicle having a storage container stored within; 
         FIGS.  3 D and  3 E  are perspective views of another prior art remotely operated delivery vehicle having a container carrier provided with conveyors; 
         FIGS.  3 F and  3 G  show an exemplary wheel base unit for the delivery vehicle; 
         FIGS.  4 A-C  show different perspective views of a delivery vehicle in a first embodiment with a connection interface for connection to an external second conveyor, where  FIGS.  4 A and  4 B  show a delivery vehicle with a container carrier and first conveyor, and  FIG.  4 C  a view with where the first conveyor has been removed to better illustrate a possible setup of a drive coupling for transferring rotational movement from a motor drive shaft to a connection interface on the vehicle body, 
         FIGS.  5 A- 5 C  show examples of an external non-motorized second conveyor to be driven by the drive coupling of the delivery vehicle, and in particular: in  FIG.  5 A  the second conveyor has been removed, in  FIG.  5 B  it is shown a cross section along the centre of the second conveyor in the moving direction of the second conveyor and the mechanical connection comprising mitre gears and rods to transfer the rotational movement from the delivery vehicle to rotational movement of the second conveyor, and in  FIG.  5 C  an opposite view where the connection facilitating movement of the second conveyor using a belt connecting a rotational axis of the second conveyor with the mitre gears and rods for transferring the rotational movement between the delivery vehicle and the second conveyor; 
         FIG.  6 A  shows an example of a delivery vehicle with a connection interface on one side of the vehicle body, wherein the connection interface is in the form of an intermediate roller arranged parallel to the first conveyor, and which rotates together with the first conveyor; 
         FIG.  6 B  shows an example of a delivery vehicle with a connection interface on one side of the vehicle body, and a second conveyor with a complementary connection interface in the form of an intermediate roller, and which rotates together with the second conveyor; 
         FIG.  7 A  shows an example of a delivery vehicle with a connection interface on two sides of the vehicle body, and a second conveyor with a complementary connection interface in the form of an intermediate roller, and which rotates together with the second conveyor, and where the delivery vehicle and the second conveyor are arranged separate from each other; 
         FIG.  7 B  is a similar view as  FIG.  7 A , however in  FIG.  7 B  the delivery vehicle and the second conveyor are arranged adjacent each other in a position where rotational movement can be transferred between the first conveyor and the second conveyor; 
         FIG.  8 A  is a side view of a delivery vehicle carrying a storage container, where the delivery vehicle has a connection interface in the form of a cog-wheel on one side of the vehicle body, and a second conveyor with a complementary connection interface in the form of an external cog-wheel, where the delivery vehicle and the second conveyor are arranged in contact with each other; 
         FIG.  8 B  is a top view of  FIG.  8 A ; 
         FIG.  9 A  is a side view of a delivery vehicle, where the delivery vehicle has a connection interface in the form of a cog-wheel on two sides of the vehicle body, and a second conveyor carrying a storage container, the second conveyor having a complementary connection interface in the form of an external cog-wheel, where the delivery vehicle and the second conveyor are arranged separate from each other; 
         FIG.  9 B  is a top view of  FIG.  9 A ; 
         FIGS.  10 A and  10 B  are perspective views from opposite sides of a system comprising a storage and retrieval system with a rail system where container handling vehicles for lifting storage containers from below operates, a delivery rail system with delivery vehicles and second conveyors arranged at a lower elevation than the rail system where the container handling vehicles operate, and a multi-level delivery rail system in three levels with delivery vehicles and second conveyors arranged on the different levels; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings. 
     The framework structure  100  of the automated storage and retrieval system  1  is constructed in accordance with the prior art framework structure  100  described above in connection with  FIGS.  1 - 3   , i.e. a number of upright members  102  and a number of horizontal members  103 , which are supported by the upright members  102 , and further that the framework structure  100  comprises a first, upper rail system  108  in the X direction and Y direction. 
     The framework structure  100  further comprises storage compartments in the form of storage columns  105  provided between the members  102 ,  103 , where storage containers  106  are stackable in stacks  107  within the storage columns  105 . 
     The framework structure  100  can be of any size. In particular it is understood that the framework structure can be considerably wider and/or longer and/or deeper than disclosed in  FIG.  1 A . For example, the framework structure  100  may have a horizontal extent of more than 700×700 columns and a storage depth of more than twelve containers. 
     The rail system  108  may be a single rail (also denoted single track) system, as is shown in  FIG.  1 B . Alternatively, the rail system  108  may be a double rail (also denoted double track) system, as is shown in  FIG.  1 C , thus allowing a container handling vehicle  201  having a footprint generally corresponding to the lateral area defined by an access opening/grid column  112  to travel along a row of grid columns even if another container handling vehicle  201  is positioned above a grid column neighboring that row. Both the single and double rail system, or a combination comprising a single and double rail arrangement in a single rail system  108 , forms a grid pattern in the horizontal plane P comprising a plurality of rectangular and uniform grid locations or grid cells  122 , where each grid cell  122  comprises a grid opening  115  being delimited by a pair of rails  110   a , 110   b  of the first rails  110  and a pair of rails  111   a , 111   b  of the second set of rails  111 . In  FIG.  1 C  the grid cell  122  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, rails  110   a  and  110   b  form pairs of rails defining parallel rows of grid cells running in the X direction, and rails  111   a  and  111   b  form pairs of rails defining parallel rows of grid cells running in the Y direction. Similarly, on a delivery rail system  308 , rails  310   a  and  310   b  form pairs of rails defining parallel rows of grid cells running in the X direction, and rails  311   a  and  311   b  form pairs of rails defining parallel rows of grid cells running in the Y direction. 
     As shown in  FIG.  1 D , each grid cell  122  has a width W c  which is typically within the interval of 30 to 150 cm, and a length L c  which is typically within the interval of 50 to 200 cm. Each grid opening  115  has a width W o  and a length L o  which is typically 2 to 10 cm less than the width W c  and the length L c  of the grid cell  122 . 
     In the X and Y directions, neighboring grid cells are arranged in contact with each other such that there is no space therebetween. 
       FIG.  3 A  is a perspective view of a prior art container handling vehicle  301  having a cantilever for carrying storage containers underneath. 
     A different automated storage and retrieval system  1  is shown in part in  FIG.  3 B . The upright members  102  constitute part of a framework structure  100  onto which a transport rail system  108  with a plurality of container handling vehicles  201 , 301  are operating. 
     Below this transport rail system  108 , near the floor level, another framework structure  300  is shown which partly extends below some of the storage columns  105  of the framework structure  100 . As for the other framework structure  100 , a plurality of vehicles  30  may operate on a rail system  308  comprising a first set of parallel rails  310  directed in a first direction X and a second set of parallel rails  311  directed in a second direction Y perpendicular to the first direction X, thereby forming a grid pattern in the horizontal plane P L  comprising a plurality of rectangular and uniform grid locations or grid cells  322 . Each grid cell of this lower rail system  308  comprises a grid opening  315  being delimited by a pair of neighboring rails  310   a , 310   b  of the first set of rails  310  and a pair of neighboring rails  311   a , 311   b  of the second set of rails  311 . 
     The part of the lower rail system  308  that extends below the storage columns  105  are aligned such that its grid cells  322  are in the horizontal plane P L  coincident with the grid cells  122  of the upper rail system  108  in the horizontal plane P. 
     Hence, with this particular alignment of the two rail systems  108 , 308 , a storage container  106  being lowered down into a storage column  105  by a container handling vehicle  250  can be received by a prior art delivery vehicle  30  configured to run on the rail system  308  and to receive storage containers  106  down from the storage column  105 . In other words, the delivery vehicle  30  is configured to receive storage containers  106  from above, preferably directly from the container handling vehicle  201 , 301 . 
       FIG.  3 C  shows an example of such a prior art delivery vehicle  30  comprising a wheel assembly  32   a ,  32   b  similar to the wheel assembly  251  described for the prior art container handling vehicle  250  and a storage container support  352  for receiving and supporting a storage container  106  delivered by an above container handling vehicle  201 , 301 . 
     After having received a storage container  106 , the delivery vehicle  30  may drive to a port or access station adjacent to the rail system  308  (not shown) for delivery of the storage container  106  for further handling and shipping. 
     Referring to  FIGS.  3 D and  3 E , it is shown perspective views another prior art remotely operated delivery vehicle having a container carrier  35  provided with a conveyor  36  arranged to convey the container  106  on and off the container carrier  35  in a horizontal direction. In this configuration, the container carrier  35  comprises a base plate, a conveyor  36  arranged on the base plate and two parallel side walls protruding upwards from the base plate. The rolling devices  32   a , 32   b  and the vehicle body  31  are equal or similar to the rolling device  32  and the vehicle body  31  described in relation to  FIG.  3 F  and  FIG.  3 G  below. 
     The conveyor  36  may be set up by, inter alia, a plurality of parallel oriented rolls  36  having a common longitudinal direction perpendicular to the two side walls. In this way the rolls  36  allow one or more storage containers  106  to be shifted onto or off the container carrier  35  while being guided by the side walls. The conveyor may be connected to a conveyor motor allowing rotation of one or more of the rolls. 
     Alternatively, the side walls are omitted, allowing the storage containers  106  to have a horizontal offset relative to a vertical center plane oriented perpendicular to the rolls longitudinal direction. Hence, the storage containers  106  may be arranged such that it extends beyond the end of the rolls in the rolls longitudinal direction. 
     In yet another alternative configuration, the conveyor may comprise a plurality of rolling balls within or on the base plate of the container carrier  35  allowing the one or more storage containers  106  to roll on top of the balls. With this configuration, and with no side walls present, the storage container  106  may be moved in any direction above the base plate. 
     As is seen in  FIG.  3 E , the container carrier  35  may be tilted by means of a dedicated displacement device  41 . The tilting may be around a pivot axis directed in the principal moving direction of the delivery vehicle  30 . If the delivery vehicle  30  is moving on perpendicular rails (see below), these principal directions would be in either the X direction or the Y direction. 
     The tilting of the displacement device  41  may for example be obtained by a lifting arm  45  coupled to the vehicle body  31  and the container carrier  35 . Further, the lifting arm  45  may be driven by a dedicated tilt motor (not shown) or the rolling device motor or both. 
     An exemplary wheel base unit for the delivery vehicle  30  is shown in  FIGS.  3 F and  3 G . The wheel base unit  2  features a wheel arrangement  32   a , 32   b  having a first set of wheels  32   a  for movement in a first direction upon a rail system (i.e. any of the top rail system  108  and the delivery rail system  308 ) and a second set of wheels  32   b  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  2 . To change the direction in which the wheel base unit may travel upon the rail system, one of the sets of wheels  32   b  is connected to a wheel displacement assembly  7 . The wheel displacement assembly is able to lift and lower the connected set of wheels  32   b  relative to the other set of wheels  32   a  such that only the set of wheels travelling in a desired direction is in contact with the rail system. The wheel displacement assembly  7  is driven by an electric motor  8 . Further, two electric motors  4 , 4 ′, powered by a rechargeable battery  6 , are connected to the set of wheels  32   a , 32   b  to move the wheel base unit in the desired direction. 
     Further referring to  FIGS.  3 F and  3 G , the horizontal periphery of the wheel base unit  2  is dimensioned to fit within the horizontal area defined by a grid cell, such that two wheel base units may pass each other on any adjacent grid cells of the rail system  108 ,  308 . In other words, the wheel base unit  2  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 WO2015/193278A1, the contents of which are incorporated herein by reference. 
     The wheel base unit  2  has a top panel/flange  9  (i.e. an upper surface) configured as a connecting interface for connection to a connecting interface of a first conveyor. The top panel  9  have a centre opening  20  and features multiple through-holes  10  (i.e. connecting elements) suitable for a bolt connection via corresponding through-holes in the first conveyor  36 . In other embodiments, the connecting elements of the top panel  9  may for instance be threaded pins for interaction with the through-holes of the first conveyor. The presence of a centre opening  20  is advantageous as it provides access to internal components of the wheel base unit, such as the rechargeable battery  6  and an electronic control system  21 . 
       FIGS.  4 A- 4 C  show different perspective views of a delivery vehicle  30  in a first embodiment with a connection interface  46  for connection to an external second conveyor (see e.g.  FIGS.  5 A- 5 C ), where  FIGS.  4 A and  4 B  show a delivery vehicle  30  with a container carrier  35  and first conveyor  36 , and  FIG.  4 C  a view with where the first conveyor has been removed to better illustrate a possible setup of a drive coupling  40  for transferring rotational movement from a motor drive shaft  47  (which is connected to a motor  48 ) to a connection interface  46  on the vehicle body  31 . The delivery vehicle  30  comprising two sets of wheels  32   a , 32   b  connected to the vehicle body  31  for engagement with an underlying rail system (not shown) and for moving the delivery vehicle  30  in the first and second directions X, Y. The rolling devices  32   a , 32   b  and the vehicle body  31  are similar to the rolling devices  32   a , 32   b  and the vehicle body  31  described in relation to  FIGS.  3 F and  3 G  above. The delivery vehicle  30  is suitable for operation on a two-dimensional rail system with rails extending in a first direction X and a second direction Y, where the second direction is perpendicular to the first direction. The delivery vehicle  30  further comprising a container carrier  35  with a first conveyor  36  for supporting a storage container (not shown) from below. A conveyor drive shaft  42  for rotating the first conveyor  36  is arranged parallel to a motor drive shaft  47 . The conveyor drive shaft  42  and the motor drive shaft  47  are rotationally coupled via a flexible force transferring means (e.g. a drive belt)  70 , which may be arranged on an outside of the vehicle body  31  as shown. Alternatively, the flexible force transferring means could be arranged at a centre of the roll if the conveyor belt was provided as a twin belt arrangement on the roller. In the embodiment of  FIGS.  4 A- 4 C , the drive coupling  40  comprises a first connection shaft  43  parallel to the motor drive shaft  47  and a second connection shaft  49  perpendicular to the first connection shaft  43 . The second connection shaft  49  is rotatably connected to the first connection shaft  43  via an angled transmission  50 , wherein the connection interface  46  is connected in both ends of the second connection shaft  49 . The connection interfaces  46  are accessible from an outer side portion of the vehicle body  31  and are disclosed as a screw coupling. The setup enables that the drive coupling  40 , and thus the connection interface(s)  46 , is rotatably connected to the motor drive shaft  47  such that when the motor drive shaft  47  is rotated, the drive coupling  40  and the connection interface(s)  46  are rotated. When the connection interface  46  is in connection with a complementary connection interface  68  on an external second conveyor  66  (see  FIGS.  5 A- 5 C ) this setup enables that rotation can be transferred to rotational movement of the second conveyor  66  at the same speed as the first conveyor  36  for transferring storage containers  106  between the first conveyor  36  and the second conveyor  66  as well as between the second conveyor  66  and the first conveyor  36 . 
       FIGS.  5 A- 5 C  show examples of an external non-motorized second conveyor  66  to be driven by the drive coupling  40  and connection interface  46  of the delivery vehicle  30  in  FIGS.  4 A- 4 C . In  FIG.  5 A  the second conveyor  66  has been removed, in  FIG.  5 B  it is shown a cross section along the centre of the second conveyor  66  in the moving direction of the second conveyor  66  as well as the mechanical connection comprising mitre gears and connection shafts to transfer the rotational movement from the delivery vehicle  30  to rotational movement of the second conveyor  66 , and in  FIG.  5 C  an opposite view where the connection facilitating movement of the second conveyor  66  using a belt connecting a rotational axis of the second conveyor with the mitre gears and connection shafts for transferring the rotational movement between the delivery vehicle  30  and the second conveyor  66 . 
     In the illustrated embodiment there are two complementary connection interface(s)  68  in the form of a toothed sprocket which can cooperate with the connection interface  46  in the form of a flat plate on the delivery vehicle  30  (see e.g.  FIGS.  4 A- 4 C ) such that they can couple torque from the delivery vehicle to the remote/external second conveyor. The complementary connection interfaces  68  are connected in each end of a first shaft  71 . 
     While two complementary connection interface(s)  68  are shown at opposite ends of the first shaft  71 , the non-motorised second conveyor may comprise only a single connection interface  68 . 
     The connection interface(s)  68  may comprise a toothed sprocket as shown, comprising a set of axially extending teeth which can mesh with a corresponding formation of the connection interface  46  on the delivery vehicle  30 , or it could comprise other shapes that are capable of transmitting torque from the connection interface  46  on the delivery vehicle  30  to the first shaft  71  of the non-motorised second conveyor  66 . For example, the connection interfaces  46 ,  68  could comprise complimentary cogs with radially or generally radially extending splines, protrusion and socket arrangements (e.g., a hexagonal or other shaped protrusion having axially extending corner edges or teeth that engage with a splined or profiled recess), or other similar connection to provide a mechanical torque connection. 
     In some embodiments, the second connection shaft  49  and the associated connection interfaces  46  could be arranged with an axis parallel to but displaced from the first shaft  71 , so that circumferential surfaces of the connection interfaces  46 ,  68  engage with one another to transmit torque from the delivery vehicle  30  to the non-motorised second conveyor. For example, the connection interfaces could be in the form of cogs or splined shafts. 
     The connection interfaces  46 ,  68  could also comprise a frictional coupling, for example, through friction pads arranged to couple torque from one end of one shaft to an end of the other, e.g., when the delivery vehicle  30  urges itself against a connection interface  68  of the non-motorised second conveyor under drive provided by a set of the delivery vehicles&#39; wheels  32   a , 32   b . The friction pads, in comparison to the connection interfaces  46 , 68  described above, may be in the form of flat discs or have planar engagement portions which are flat in a radial plane perpendicular to the shaft axis. Additional assistance could be provided to the torque coupling using electromagnetic clamps or suction devices which help to clamp the friction pads together during transmission of the torque. 
     The first shaft  71  is connected to one end of a perpendicularly arranged second shaft  72 , where rotational movement between the first and second shafts  71 , 72  is provided via mitre gears  73 . An opposite end of the second shaft  72  may extend beyond the width of the second conveyor  66 . The second shaft  72  is parallel to a second conveyor drive shaft  74 . The opposite end of the second shaft  72  is rotationally connected to the second conveyor drive shaft  74  via a flexible force transferring means (e.g. drive belt)  75 . 
     Although it is disclosed in  FIGS.  4 A- 4 C and  5 A- 5 C  that the motor  48  and motor drive shaft  47  are arranged as part of the delivery vehicle  30 , it is clear that the motor  48  and drive shaft  47  can be arranged in the connection with the second conveyor  66  such that rotational movement can be transferred from the complementary connection interface  68  on the second conveyor  66  to the connection interface  46  on the delivery vehicle instead. 
       FIG.  6 A  shows an example of a delivery vehicle  30  with a connection interface on one side of the vehicle body  31 , wherein the connection interface is in the form of an intermediate roller  67  arranged parallel to the first conveyor  36 . The intermediate roller  67  rotates together with the first conveyor  36 . The intermediate roller  67  is thus connected to the first conveyor  36  and rotation can be achieved by either friction between the surface of the first conveyor  36  and the intermediate roller  67  or by a mechanical connection such as a belt running between a conveyor drive shaft and a rotary shaft of the intermediate roller  67  (not shown). When the delivery vehicle  31  has positioned itself next to the second conveyor  66 , rotational movement is transferred from the first conveyor  36  via the intermediate roller  67  and to the second conveyor  66 . The surface of the intermediate roller  67  and the surface of the second conveyor  66  are frictionally connected such that the transfer of the rotational movement is achieved. In order to provide sufficient friction between the surfaces of the intermediate roller  67  and the second conveyor  66 , preferably all wheels in both sets of wheels  32   a , 32   b  are in contact with the underlying rail system  108 , 308  thereby ensuring a stable transfer of the storage containers between the first and second conveyors  36 , 66  with reduced risk that the delivery vehicle  30  unintentionally moves. 
       FIG.  6 B  shows an example of a delivery vehicle  30  with a connection interface on one side of the vehicle body  31 , and a second conveyor  66  with a complementary connection interface in the form of an intermediate roller  67 . The intermediate roller  67  is connected to the second conveyor  66  and rotates together with the second conveyor  66  and rotation can be achieved by either friction between the surface of the first conveyor  36  and the intermediate roller  67  or by a mechanical connection such as a belt running between a second conveyor drive shaft and a rotary shaft of the intermediate roller  67  (not shown). When the delivery vehicle  31  has positioned itself next to the second conveyor  66 , rotational movement is transferred from the second conveyor  36  via the intermediate roller  67  and to the first conveyor  66 . The surface of the intermediate roller  67  and the surface of the first conveyor  66  are frictionally connected such that the transfer of the rotational movement is achieved. In order to provide sufficient friction between the surfaces of the intermediate roller  67  and the first conveyor  66 , the delivery vehicle  31  can lower itself onto the intermediate roller  67 . Furthermore, preferably all wheels in both sets of wheels  32   a , 32   b  are in contact with the underlying rail system  108 , 308  thereby ensuring a stable transfer of the storage containers between the first and second conveyors  36 , 66  with reduced risk that the delivery vehicle  30  unintentionally moves. 
     The vehicle body  31  may comprise a recess  69  for accommodating the intermediate roller  67 , regardless whether the intermediate roller  67  is connected to the first conveyor  36  or the second conveyor  66 . 
       FIG.  7 A  shows an example of a delivery vehicle  30  with a connection interface on two sides of the vehicle body  31 , and a second conveyor  66  with a complementary connection interface in the form of an intermediate roller  67 . The remaining features are similar to the embodiment described with reference to  FIG.  6 B  and will not be repeated herein. 
       FIG.  7 B  is a similar view as  FIG.  7 A , however in  FIG.  7 B  the delivery vehicle  31  and the second conveyor  66  are arranged adjacent each other in a position where rotational movement can be transferred between the first conveyor  36  and the second conveyor  66 . In order to provide sufficient friction between the surfaces of the intermediate roller  67  and the first conveyor  66 , the delivery vehicle  31  can lower itself onto the intermediate roller  67 . Furthermore, preferably all wheels in both sets of wheels  32   a , 32   b  are in contact with the underlying rail system  108 , 308  thereby ensuring a stable transfer of the storage containers between the first and second conveyors  36 , 66  with reduced risk that the delivery vehicle  30  unintentionally moves. 
       FIG.  8 A  is a side view of a delivery vehicle  30  carrying a storage container  106 , where the delivery vehicle  30  has a connection interface in the form of a cog-wheel  51  on one side of the vehicle body  31 . The second conveyor  36  has a complementary connection interface in the form of an external cog-wheel  52 . In  FIG.  8 A  the delivery vehicle  30  and the second conveyor  66  are arranged in contact with each other. As disclosed in the Figure, the cog-wheel  51  is arranged at the end of the first conveyor  36 , e.g., mounted on the drive shaft  42  of the first conveyor to engage with the external cog-wheel  52  of the second conveyor  66 . A drive gear (not shown) can be mounted on the second conveyor drive shaft  74  to transfer the rotational movement. An idler gear or similar may be arranged to reverse the rotation such that the first and second conveyors  36 ,  66  rotate in the same direction. 
       FIG.  8 B  is a top view of  FIG.  8 A  showing two cog-wheels  51  arranged on opposite ends of the conveyor drive shaft  42  to cooperate with two external cog-wheels  52  on opposite ends of the second conveyor  66  to transfer rotational movement between the first cog-wheels  51  and the external cog-wheels  52 . This setup enables that when a cog-wheel  51  of the first conveyor  36  is in contact with a cog-wheel  52  of the second conveyor  66 , rotational movement of the first conveyor  36  is transferred to the second conveyor  66  via the cog-wheels  51 , 52 , or vice versa. As such, storage containers  106  can be transferred between the first conveyor  36  and the second conveyor  66  as well as between the second conveyor  66  and the first conveyor  36 . 
       FIG.  9 A  is a side view of a delivery vehicle  30 , where the delivery vehicle  30  has a connection interface in the form of a cog-wheel  51  on two sides of the vehicle body  31  (i.e. on both ends of the first conveyor  36 ) and a second conveyor  66  carrying a storage container  106 . This setup enables the possibility that the delivery vehicle  31  can connect to external cog-wheels  52  on both ends of the delivery vehicle  31 . Furthermore, if arranging a number of delivery vehicles  31  with this particular configuration with the conveyors  36  one after the other, a continuous conveyor may extend all the way from the delivery vehicle  31  at one end to a delivery vehicle  31  or second conveyor  66  at an opposite end. In the disclosed example, the second conveyor  66  has a complementary connection interface in the form of an external cog-wheel  52 . The delivery vehicle  30  and the second conveyor  66  are connected to each other. When the delivery vehicle  30  is positioned next to the second conveyor  66 , preferably all wheels in both sets of wheels  32   a , 32   b  are in contact with the underlying rail system  108 , 308  thereby ensuring a stable transfer of the storage containers between the first and second conveyors  36 , 66  with reduced risk that the delivery vehicle  30  unintentionally moves. 
       FIG.  9 B  is a top view of  FIG.  9 A . 
     In one embodiment the connection interfaces  44  do not protrude beyond the footprint of the wheel base unit  2 . The delivery vehicles  30  may then pass each other on adjacent tracks (i.e. double tracks), without the connection interfaces  44  engaging one another or without the connection interfaces  44  colliding with adjacent delivery vehicles  30 . Conceivably, if the connection interfaces  44  did protrude to some extent they could be arranged at different heights on opposite sides of the delivery vehicle  30  and grooves could be provided to allow the connection interfaces  44  to sweep past without contact. 
     Alternatively, if the second conveyor  66  is non-motorized, the connection interface  44  may protrude in order to engage the connection interface  44  of the delivery vehicle  30 . However, depending on the positioning of the second conveyor  66  with respect to the ail system  108 , 308 , that might require a direct on approach towards the second conveyor  66  by the delivery vehicle  30  so that the connection interfaces  44 , 46 , 47 , 68  engage properly, and that may mean that the grid cell  122  in front of it can only be used in one direction of travel towards and away from the second conveyor  66 . Alternatively, the second conveyor  66  could be stepped back a distance, e.g., a few centimeters or so, so that its connection interface  68  does not protrude into the neighboring grid cell, in which case, the delivery vehicle  30  would need to move a similar distance into the grid cell with the second conveyor  66  (so that the connection interfaces can be engaged and torque transmitted from one to the other). 
       FIGS.  10 A and  10 B  are perspective views from opposite sides of a system where a delivery vehicle  30  according to the invention can be used. The system comprising a storage and retrieval system with a rail system where container handling vehicles  301  for lifting storage containers  106  from below operates. A delivery rail system  308  with delivery vehicles  30  and second conveyors  66  are arranged at a lower elevation than the rail system where the container handling vehicles  301  operate. A multi-level delivery rail system  308  in three levels are disclosed with delivery vehicles  30  and second conveyors  66  arranged on the different levels. The delivery vehicles  30  can pick up storage containers  106  from a buffer in a lower end of a port column  119 . The storage containers  106  can be transferred into the buffer by being lowered onto, or retrieved from, the second conveyor  66  either by container handling vehicles  301  operating on the rail system  108  in a plane above the second conveyor  66  or by delivery vehicles with a first conveyor  36  in the same plane as the second conveyor  66 . Possibly, two or more storage containers  106  can be placed on top of one another on the second conveyor  66 . 
     It is further disclosed several access stations  65  or picking station arranged adjacent a second conveyor  66  from which a human or robotic operator may pick one or more items from the storage container  106 . In order to increase safety for the operator, the second conveyor  66  may be of sufficient length such that the operator&#39;s distance from the rail system  308  is sufficient to perform safe handling of the items in the storage containers  106  or boxes. 
     The delivery vehicles  30 , with or without storage container(s)  106  or box(es), can move between the different levels of the delivery rail system  308  using a dedicated delivery vehicle lift (not shown). 
     If using delivery vehicles  30  with an external torque or power output, i.e. a connection interface  46  which can cooperate with a complementary connection interface  68  on the second conveyor  66 , provides for modularity in terms of where to arrange the second conveyors  66  as there is not need for software nor power to operate the second conveyor  66  and the second conveyors  66  can be easily re-arranged to other locations dependent on the pending requirements. 
     In the preceding description, various aspects of the delivery vehicle and the automated storage and retrieval system according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the system and its workings. 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 to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention. 
     
       
         
           
               
             
               
                   
               
               
                 List of reference numbers 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                  1 
                 Prior art storage and retrieval system 
               
               
                  2 
                 Wheel base unit 
               
               
                  3 
                 Container supporting unit 
               
               
                     4, 4′ 
                 Electric motor 
               
               
                  6 
                 Rechargeable battery 
               
               
                  7 
                 Wheel displacement assembly 
               
               
                  8 
                 Electric motor for wheel displacement assembly 
               
               
                  9 
                 Top panel/flange 
               
               
                 10 
                 Through-holes 
               
               
                 20 
                 Centre opening 
               
               
                 21 
                 Electronic control system 
               
               
                 30 
                 Delivery vehicle 
               
               
                 31 
                 Vehicle body 
               
               
                 32a, 32b 
                 Wheel arrangement, first and second set of wheels 
               
               
                 35 
                 Container carrier 
               
               
                 36 
                 First conveyor 
               
               
                 40 
                 Drive coupling 
               
               
                 41 
                 Displacement device/Tilting device 
               
               
                 42 
                 Conveyor drive shaft 
               
               
                 43 
                 First connection shaft 
               
               
                 44 
                 Connection interface 
               
               
                 45 
                 Lifting arm 
               
               
                 46 
                 Connection interface (first and second) 
               
               
                 47 
                 Motor drive shaft 
               
               
                 48 
                 Motor 
               
               
                 49 
                 Second connection shaft 
               
               
                 50 
                 Angled transmission 
               
               
                 51 
                 Cog wheel 
               
               
                 52 
                 External cog wheel (in connection with second 
               
               
                   
                 conveyor) 
               
               
                 65 
                 Access station 
               
               
                 66 
                 Second conveyor/external conveyor/Conveyor line 
               
               
                 67 
                 Intermediate roller 
               
               
                 68 
                 Complementary connection interface 
               
               
                 69 
                 Recess in vehicle body 
               
               
                 70 
                 Flexible force transferring means/Drive belt of 
               
               
                   
                 first conveyor 
               
               
                 71 
                 First shaft 
               
               
                 72 
                 Second shaft 
               
               
                 73 
                 Mitre gears 
               
               
                 74 
                 Second conveyor drive shaft 
               
               
                 75 
                 Flexible force transferring means/Drive belt of 
               
               
                   
                 second conveyor 
               
               
                 100  
                 Framework structure 
               
               
                 102  
                 Upright members of framework structure 
               
               
                 103  
                 Horizontal members of framework structure 
               
               
                 104  
                 Storage grid 
               
               
                 105  
                 Storage column 
               
               
                 106  
                 Storage container 
               
               
                 106′  
                 Particular position of storage container 
               
               
                 107  
                 Stack 
               
               
                 108  
                 Rail system 
               
               
                 110, 110a, 110b 
                 Parallel rails in first direction (X) 
               
               
                 111, 111a, 111b 
                 Parallel rail in second direction (Y) 
               
               
                 112  
                 Access opening 
               
               
                 115  
                 Grid opening 
               
               
                 119  
                 First port column 
               
               
                 120  
                 Second port column 
               
               
                 122  
                 Grid cell 
               
               
                 201  
                 Prior art storage container vehicle 
               
               
                 201a 
                 Vehicle body of the storage container vehicle 201 
               
               
                 201b 
                 Drive means/wheel arrangement, first direction (X) 
               
               
                 201c 
                 Drive means/wheel arrangement, second direction (Y) 
               
               
                 300  
                 Delivery framework structure 
               
               
                 301  
                 Prior art cantilever storage container vehicle 
               
               
                 301a 
                 Vehicle body of the storage container vehicle 301 
               
               
                 301b 
                 Drive means in first direction (X) 
               
               
                 301c 
                 Drive means in second direction (Y) 
               
               
                 308  
                 Delivery rail system 
               
               
                 310, 310a, 310b 
                 First set of parallel rails in first direction (X) 
               
               
                   
                 on delivery rail system 
               
               
                 311, 311a, 311b 
                 Second set of parallel rails in second direction (Y) 
               
               
                   
                 on delivery rail system 
               
               
                 315  
                 Grid opening in delivery rail system 
               
               
                 322  
                 Grid cell of delivery rail system 
               
               
                 352  
                 Storage container support 
               
               
                 500  
                 Control system 
               
               
                 X 
                 First direction 
               
               
                 Y 
                 Second direction 
               
               
                 Z 
                 Third direction