Method, system and computer program product for moving storage containers

Abstract

The present invention relates to a system, method, and computer program product for moving storage containers. The method includes assigning a task to a container handling vehicle to retrieve a storage container from a storage column and deliver the storage container to a port area of ​​an access station. The method instructs the container handling vehicle to retrieve the storage container from the storage column. The method determines a virtual buffer location on a rail system between the storage column and the port area. The method instructs the container handling vehicle to move the storage container toward the virtual buffer location on the rail system. If the current location of the storage container differs from the virtual buffer location and a column in the port area is available, the method instructs the container handling vehicle to move the storage container to the column in the port area and delivers the storage container to the column in the port area.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to automated storage and retrieval systems for the storage and retrieval of containers, and more particularly to methods, systems, and computer program products for moving storage containers. [Background technology]

[0002] Background and Prior Art FIG. 1 discloses a prior art automated storage and retrieval system 1 having a framework structure 100, and FIGS. 2, 3 and 4 disclose three different prior art container handling vehicles 201, 301, 401 suitable for operating on such a system 1.

[0003] The framework structure 100 comprises upright members 102 and a storage volume comprising storage columns 105 arranged in rows between the upright members 102. In these storage columns 105, storage containers 106, also known as bins, are stacked on top of each other to form stacks 107. The members 102 may typically be made of metal, for example extruded aluminum.

[0004] The framework 100 of the automated storage and retrieval system 1 comprises a rail system 108 disposed across the top of the framework 100, on which a plurality of container handling vehicles 201, 301, 401 may operate to raise and lower storage containers 106 from and into the storage columns 105, and to transport storage containers 106 up the storage columns 105. The rail system 108 comprises a first set of parallel rails 110 disposed to guide movement of the container handling vehicles 201, 301, 401 in a first direction X across the top of the framework 100, and a second set of parallel rails 111 disposed perpendicular to the first set of parallel rails 110 to guide movement of the container handling vehicles 201, 301, 401 in a second direction Y perpendicular to the first direction X. The containers 106 stored in the columns 105 are accessed by container handling vehicles 201, 301, 401 through access openings 112 in the rail system 108. The container handling vehicles 201, 301, 401 can move laterally above the storage columns 105, i.e. in a plane parallel to the horizontal XY plane.

[0005] The uprights 102 of the framework 100 can be used to guide the storage containers while raising the containers out of the columns 105 and lowering the containers into the columns 105. The stacks 107 of containers 106 are typically freestanding.

[0006] Each prior art container handling vehicle 201, 301, 401 comprises a vehicle body 201a, 301a, 401a and first and second sets of wheels 201b, 201c, 301b, 301c, 401b, 401c that respectively enable lateral movement of the container handling vehicle 201, 301, 401 in the X and Y directions. Two wheels in each set are fully visible in Figures 2, 3, and 4. The first set of wheels 201b, 301b, 401b are positioned to engage two adjacent rails of the first set of rails 110, and the second set of wheels 201c, 301c, 401c are positioned to engage two adjacent rails of the second set of rails 111. At least one of the sets of wheels 201b, 201c, 301b, 301c, 401b, 401c can be raised and lowered so that a first set of wheels 201b, 301b, 401b and / or a second set of wheels 201c, 301c, 401c can be engaged with a respective set of rails 110, 111 at any one time.

[0007] Each prior art container handling vehicle 201, 301, 401 also includes a lifting device for vertically transporting the storage containers 106, e.g., for raising the storage containers 106 from the storage columns 105 and lowering the storage containers 106 into the storage columns 105. The lifting device includes one or more gripping / engaging devices adapted to engage with the storage containers 106, and these gripping / engaging devices can be lowered from the vehicle 201, 301, 401 such that the position of the gripping / engaging devices relative to the vehicle 201, 301, 401 can be adjusted in a third direction Z that is perpendicular to the first direction X and the second direction Y. Parts of the gripping devices of the container handling vehicles 301, 401 are shown in FIGS. 3 and 4, designated by reference numerals 304, 404. The gripping devices of the container handling device 201 are not shown in FIG. 2 because they are installed within the vehicle body 201a.

[0008] Conventionally, and for purposes of this application, Z=1 identifies the top available layer for a storage container below rails 110, 111, i.e., the layer immediately below rail system 108; Z=2 identifies the second layer below rail system 108; Z=3 identifies the third layer, and so on. In the exemplary prior art disclosed in FIG. 1, Z=8 identifies the lowest bottom layer of a storage container. Similarly, X=1...n and Y=1...n identify the location of each storage column 105 in the horizontal plane. Thus, by way of example, using the Cartesian coordinate system X, Y, Z shown in FIG. 1, the storage container identified as 106' in FIG. 1 can be said to occupy storage location X=17, Y=1, Z=6. Container handling vehicles 201, 301, 401 can be said to travel in layer Z=0, and each storage column 105 can be identified by its X and Y coordinates. Therefore, the storage containers shown in FIG. 1 extending above the rail system 108 can also be said to be located in layer Z=0.

[0009] The storage volume of framework structure 100 may be referred to as a grid 104, and the possible storage locations within this grid may be referred to as storage cells. Each storage column may be identified by a location in the X and Y directions, while each storage cell may be identified by a container number in the X, Y, and Z directions.

[0010] Each prior art container handling vehicle 201, 301, 401 includes a storage compartment or space for receiving and storing the storage containers 106 as they are transported across the rail system 108. This storage space may include a cavity disposed within the vehicle body 201 a, 401 a, as shown in Figures 2 and 4 and described, for example, in International Patent Application Publication Nos. WO 2015 / 193278 and WO 2019 / 206487, the contents of which are incorporated herein by reference.

[0011] Figure 3 shows an alternative configuration of a container handling vehicle 301 having a cantilever structure. Such a vehicle is described in detail, for example, in Norwegian Patent No. 317366, the contents of which are also incorporated herein by reference.

[0012] 2 may have a footprint covering an area having dimensions in the X and Y directions approximately equal to the lateral extent of the storage column 105, as described, for example, in International Patent Application Publication No. WO 2015 / 193278, the contents of which are incorporated herein by reference. As used herein, the term "lateral" may mean "horizontal."

[0013] Alternatively, the cavity container handling vehicle 401 may have a footprint that is larger than the lateral area defined by the storage columns 105 as shown in Figures 1 and 4, as disclosed, for example, in International Patent Application Publication No. WO 2014 / 090684 or International Patent Application Publication No. WO 2019 / 206487.

[0014] The rail system 108 typically includes rails with grooves along which vehicle wheels travel. Alternatively, the rails may include upwardly protruding elements, and the vehicle wheels may include flanges to prevent derailment. These grooves and upwardly protruding elements are collectively referred to as tracks. Each rail may include one track, or each rail 110, 111 may include two parallel tracks. In other rail systems 108, each rail in one direction (e.g., the X direction) may include one track, and each rail in the other perpendicular direction (e.g., the Y direction) may include two tracks. Also, each rail 110, 111 may include two track members fastened together, each providing one of the pair of tracks provided by each rail.

[0015] International Patent Application Publication No. WO 2018 / 146304, the contents of which are incorporated herein by reference, illustrates a typical configuration of a rail system 108 with rails and parallel tracks in both the X and Y directions.

[0016] In the framework 100, most 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, columns 119 and 120 are dedicated columns used by container handling vehicles 201, 301, 401 to drop off and / or pick up storage containers 106 so that the storage containers 106 can be transported to an access station (not shown) where they can be accessed from outside the framework 100 or transferred out of or into the framework 100. In the art, such locations are commonly referred to as "ports," and the columns in which the ports are located may be referred to as "port columns" 119, 120. Transport to the access station may be in any direction, be it horizontal, inclined, and / or vertical. For example, storage containers 106 may be placed in random or dedicated columns 105 within framework 100 and then picked up by any container handling vehicle and transported to port columns 119, 120 for further transport to an access station. Transport from the port to the access station may require movement along a variety of different directions by means such as delivery vehicles, trolleys, or other transport lines. Note that the term "inclined" refers to transport of storage containers 106 with a general transport direction anywhere between horizontal and vertical.

[0017] In FIG. 1, the first port column 119 may be, for example, a dedicated drop-off port column where container handling vehicles 201, 301, 401 can drop off storage containers 106 being transported to an access station or transfer station, and the second port column 120 may be a dedicated pickup port column where container handling vehicles 201, 301, 401 can pick up storage containers 106 being transported from an access station or transfer station.

[0018] An access station may typically be a picking or stocking station where product items are removed from or placed into storage containers 106. At a picking or stocking station, the storage containers 106 are typically not removed from the automated storage and retrieval system 1 but are instead placed back into the framework 100 once accessed. A port may also be used to transfer storage containers to another storage facility (e.g., another framework or another automated storage and retrieval system), a transport vehicle (e.g., a train or lorry), or a production facility.

[0019] A conveyor system with multiple conveyors is typically employed to transport storage containers between the port columns 119, 120 and the access stations.

[0020] If the port columns 119, 120 and the access stations are located on different levels, the conveyor system may include a lift device having a vertical component for vertically transporting the storage containers 106 between the port columns 119, 120 and the access stations.

[0021] A conveyor system may be arranged to transfer storage containers 106 between different framework structures, for example as described in International Patent Application Publication No. WO 2014 / 075937, the contents of which are incorporated herein by reference.

[0022] 1 , one of the container handling vehicles 201, 301, 401 is commanded to retrieve the target storage container 106 from its location and transport it to the drop-off port column 119. This operation involves moving the container handling vehicle 201, 301, 401 to a location above the storage column 105 where the target storage container 106 is located, using a lifting device (not shown) of the container handling vehicle 201, 301, 401 to retrieve the storage container 106 from the storage column 105, and transporting the storage container 106 to the drop-off port column 119. If the target storage container 106 is located deep within the stack 107, i.e., if one or more of the other storage containers 106 are positioned above the target storage container 106, the operation also involves temporarily moving the storage container(s) positioned above it before lifting the target storage container 106 from the storage column 105. This step, sometimes referred to in the art as "digging," may be performed using the same container handling vehicle that is later used to transport the target storage container to the drop-off port column 119, or using one or more other cooperating container handling vehicles. Alternatively, or in addition, the automated storage and retrieval system 1 may have container handling vehicles 201, 301, 401 dedicated to the temporary retrieval of storage containers 106 from the storage columns 105. Once the target storage container 106 is removed from the storage column 105, the temporarily removed storage container 106 can be repositioned in the original storage column 105. However, the removed storage container 106 may alternatively be reinstalled in another storage column 105.

[0023] When a storage container 106 is to be stored in one of the columns 105, one of the container handling vehicles 201, 301, 401 is commanded to pick up the storage container 106 from the pickup port column 120 and transport the storage container 106 to a location above the storage column 105 where it is to be stored. After any storage container 106 located at a target location in the stack 107 or information about a target location is removed, the container handling vehicle 201, 301, 401 positions the storage container 106 at the desired location. The removed storage container 106 can then be lowered back into the storage column 105 or reinstalled in another storage column 105.

[0024] To monitor and control the automated storage and retrieval system 1, for example, the location of each storage container 106 within the framework structure 100, the contents of each storage container 106, and the movements of the container handling vehicles 201, 301, 401 so that the desired storage container 106 can be delivered at the desired time and at the desired location without the container handling vehicles 201, 301, 401 colliding with each other, the automated storage and retrieval system 1 typically includes a control system 500 that is computerized and typically includes a database for tracking the storage containers 106.

[0025] FIG. 5 is a schematic top view of the prior art rails of the automated storage and retrieval system 1 as illustrated in FIG. 1. FIG. 5 shows the rail system 108, storage columns 105, port columns 119, 120, and a storage container 106 positioned in one of the storage columns 105. The port columns 119, 120 are part of the port area 510 of the access station, which, as previously described, is a location on the automated storage and retrieval system 1 where product items are removed from or positioned into the storage container 106. The access station may be positioned at the base of the port column 119, 120. A container handling vehicle 201, 301, 401 delivering a storage container 106 to the port column 119, 120 moves toward the port column so that the storage container 106 enters the port column, and delivers the storage container to the access station by lowering the storage container 106 through the port column 119, 120.

[0026] The access station may also be located at the top of the port column 119, 120. This may be the case when the access station is a robotic picking station, as described in WO 2016 / 198565. Here, the container handling vehicle 201, 301, 401 moves toward the port column 119, 120 and delivers the storage container 106 to the access station either by lowering the storage container 106 through the port column 119, 120 to a level just below the rail system 108, for example, to Z=1, or by lowering the storage container 106 on the port column 119, 120 above the rail system 108, i.e., to Z=0.

[0027] 5, the port area 510 of the access station may also include two buffer columns 519, 520 adjacent to the port columns 119, 120. The buffer columns 519, 520 are temporary locations for the container handling vehicles 201, 301, 401 to hold the storage containers 106.

[0028] The buffer columns 519, 520 are used to schedule container handling vehicles 201, 301, 401 to move towards the port columns 119, 120 early enough to meet delivery times. To obtain maximum performance and flow at the access station, container handling vehicles 201, 301, 401 should arrive at the buffer columns 519, 520 before the previous container handling vehicle 201, 301, 401 is completed at the access station's port columns 119, 120. Once the previous container handling vehicle 201, 301, 401 is completed at the port columns 119, 120 and moving away, the next container handling vehicle 201, 301, 401, holding its storage container 106 in the buffer columns 519, 520, will be ready to move into the previous container handling vehicle's location without unnecessary waiting. Long waiting times for container handling vehicles 201, 301, 401 in buffer columns 519, 520 may waste container handling vehicle resources. Therefore, the central control system 500 may make a decision to deliver storage containers 106 in buffer columns 519, 520.

[0029] The storage containers 106 should arrive at the access station's port area 510 just in time. Waiting for storage containers 106 reduces the performance of the access station (usually measured in storage containers / hour). If a storage container 106 scheduled to be transported to the port area 510 does not arrive at the port area 510 before it was scheduled to be delivered because it is located on the rail system 108 far away from the port area 510, delays will occur at the access station.

[0030] Each access station has a limited number of buffer columns 519, 520 available to receive storage containers because each buffer column 519, 520 replaces a storage column 105 of the automated storage and retrieval system 1. The limited number of buffer columns 519, 520 limits the number of storage containers 106 that can be planned / moved towards the port area 510 of the access station.

[0031] What is needed is a system and method for improving the performance of an access station. [Prior art documents] [Patent documents]

[0032] [Patent Document 1] International Patent Application Publication No. 2015 / 193278 [Patent Document 2] International Patent Application Publication No. 2019 / 206487 Summary of the Invention [Means for solving the problem]

[0033] The present invention is set forth and characterized in the independent claims, while the dependent claims describe further features of the invention.

[0034] In one aspect, the present invention relates to a method for moving storage containers using one of a plurality of container handling vehicles over a rail system disposed at least partially across a framework of an automated storage and retrieval system, on which the plurality of container handling vehicles are operable to retrieve and deliver storage containers from and into storage columns disposed in rows between upright members of the framework, and to move the storage containers to and from a port area of ​​an access station, the method comprising the steps of: assigning a task to one of a plurality of container handling vehicles to retrieve a storage container from one of the storage columns and deliver the storage container to a port area; - instructing a container handling vehicle to retrieve a storage container from one of the storage columns; - determining a virtual buffer location on the rail system between the storage column and the port area; - instructing a container handling vehicle to move a storage container towards a virtual buffer location on the rail system; - repeatedly receiving data on the current location of storage containers on the rail system and the current availability of access stations; - instructing a container handling vehicle to move the storage container to a column in the port area if the current location of the storage container is different from the virtual buffer location and a column in the port area is available; - instructing a container handling vehicle to deliver the storage container into a column in the port area; is implemented by a central control system in communication with the access stations and a local controller in each of the plurality of container handling vehicles.

[0035] An advantage of the first aspect of the present invention is that it reduces waiting times at access stations for storage containers with long travel distances to the access station, effectively increasing access station performance (storage containers / time). Another advantage of the first aspect of the present invention is that virtual buffer locations may reduce the number of buffer columns required. Reducing the number of buffer columns required between access stations may allow access stations to be positioned closer to each other.

[0036] In one embodiment of the first aspect, the step of determining a virtual buffer location on the rail system includes defining the virtual buffer location as any storage column within a first predetermined radius of one of the columns of the port area as the virtual buffer location.

[0037] In one embodiment of the first aspect, the step of determining a virtual buffer location on the rail system includes selecting a storage column close to the port area to be the virtual buffer location, the storage column having space to receive the storage container.

[0038] In one embodiment of the first aspect, the step of determining a virtual buffer location on the rail system includes selecting a storage column closest to a port area having space to receive a storage container to be the virtual buffer location.

[0039] In one embodiment of the first aspect, the method comprises: - instructing a container handling vehicle to move to a column of an access station when the current position of the storage container is at a virtual buffer position and a column of a port area is available; - commanding a container handling vehicle to deliver the storage container into a column of access stations; Includes.

[0040] In one embodiment of the first aspect, the method includes determining, when a current location of the storage container is at a virtual buffer location and an access station is not available, to instruct one of a plurality of container handling vehicles to deliver the storage container to the virtual buffer location.

[0041] In one embodiment of the first aspect, the method includes determining, when a current location of the storage container is at a virtual buffer location and an access station is not available, to instruct one of a plurality of container handling vehicles to deliver the storage container to a virtual buffer location other than the virtual buffer location.

[0042] In one embodiment of the first aspect, the method includes determining, when a deadline for delivering the storage container into a column of the port area exceeds a deadline threshold, to instruct one of a plurality of container handling vehicles to deliver the storage container to a virtual buffer location when a deadline for delivering the storage container to the virtual buffer location exceeds a deadline threshold.

[0043] In one embodiment of the first aspect, the method includes determining to instruct one of a plurality of container handling vehicles to deliver a storage container to a virtual buffer location when the access station has been idle for a time that exceeds an idle threshold.

[0044] In a second aspect, the present invention relates to an automated storage and retrieval system, the automated storage and retrieval system comprising: a framework structure comprising upright members arranged at least partially across the framework structure; - storage columns arranged in rows between the upright members of the framework structure; an access station comprising a port area; a plurality of container handling vehicles operable to retrieve storage containers from and deliver storage containers into the storage columns, and to move storage containers to and from the port area of ​​the access station, each container handling vehicle comprising a local controller; a central control system operable to communicate with the access station and with a local controller in each of a plurality of container handling vehicles, the central control system comprising: assigning a task to one of a plurality of container handling vehicles to retrieve a storage container from one of the storage columns and deliver the storage container to a port area; - commanding a container handling vehicle to retrieve a storage container from one of the storage columns; - determining a virtual buffer location on the rail system between the storage column and the port area; commanding a container handling vehicle to move a storage container towards a virtual buffer location; - repeatedly receiving data on the current location of storage containers on the rail system and the current availability of access stations; - instructing a container handling vehicle to move the storage container to a column in the port area if the current location of the storage container is different from the virtual buffer location and a column in the port area is available; - instructing a container handling vehicle to deliver the storage container into a column in the port area; a central control system adapted to Equipped with.

[0045] An advantage of the second aspect of the present invention is that it reduces waiting times at the access station for storage containers that have long travel distances to the access station, effectively increasing the performance (storage containers / time) of the access station. Another advantage of the first aspect of the present invention is that virtual buffer locations may reduce the number of buffer columns required. Reducing the number of buffer columns required between access stations may allow the access stations to be positioned closer to each other.

[0046] In one embodiment of the second aspect, the system is adapted to determine a virtual buffer location on the rail system by defining the virtual buffer location as any storage column within a first predetermined radius of one of the columns of the port area as the virtual buffer location.

[0047] In one embodiment of the second aspect, the system is adapted to determine a virtual buffer location on the rail system by selecting a storage column close to the port area to be the virtual buffer location, the storage column being one that has space to receive the storage container.

[0048] In one embodiment of the second aspect, the system is adapted to determine a virtual buffer location on the rail system by selecting a storage column closest to a port area having space to receive a storage container to be the virtual buffer location.

[0049] In one embodiment of the second aspect, the system comprises: - instructing a container handling vehicle to move to a column of an access station when the current position of the storage container is at a virtual buffer position and a column of a port area is available; - commanding a container handling vehicle to deliver the storage container into a column of access stations; The system is adapted to:

[0050] In one embodiment of the second aspect, the system is adapted to determine, when the current location of the storage container is at the virtual buffer location and no access station is available, to instruct a container handling vehicle to deliver the storage container to the virtual buffer location.

[0051] In one embodiment of the second aspect, the system is adapted to determine, when the current location of the storage container is at a virtual buffer location and no access station is available, to instruct the container handling vehicle to deliver the storage container to a virtual buffer location other than the virtual buffer location.

[0052] In one embodiment of the second aspect, the system is adapted to instruct a container handling vehicle to deliver the storage container to a virtual buffer location when a deadline for delivering the storage container to a column in the port area exceeds a deadline threshold.

[0053] In one embodiment of the second aspect, the system is adapted to instruct a container handling vehicle to deliver a storage container to a buffer location when the access station has been idle for a time exceeding an idle threshold.

[0054] In a third aspect, the present invention relates to a computer program product for a central control system of the second aspect of the invention, the computer program product comprising instructions for carrying out the method of the first aspect of the invention when executed on the control system.

[0055] The third aspect of the present invention has the same advantages as the first and second aspects of the present invention. [Brief explanation of the drawings]

[0056] The following drawings are included to facilitate an understanding of the invention, and illustrate embodiments of the invention, which are described herein by way of example only:

[0057] [Figure 1] FIG. 1 is a perspective view of a framework structure of a prior art automated storage and retrieval system.

[0058] [Figure 2] FIG. 2 is a perspective view of a prior art container handling vehicle having an internally disposed cavity for carrying storage containers therein.

[0059] [Figure 3] FIG. 3 is a perspective view of a prior art container handling vehicle having a cantilever for carrying storage containers underneath.

[0060] [Figure 4] FIG. 4 is a perspective view from below of a prior art container handling vehicle having internally disposed cavities for carrying storage containers therein.

[0061] [Figure 5]FIG. 5 is a schematic diagram of a prior art automated storage and retrieval system.

[0062] [Figure 6] FIG. 6 is a schematic diagram of an embodiment of the present invention.

[0063] [Figure 7] FIG. 7 is a schematic diagram of an embodiment of the present invention.

[0064] [Figure 8] FIG. 8 is a flowchart of a method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0065] (Detailed Description of the Invention) In the following, embodiments of the invention will be described in more detail with reference to the accompanying drawings, in which it should be understood, however, that the drawings are not intended to limit the invention to the subject matter depicted therein.

[0066] The framework 100 of the automated storage and retrieval system 1 is constructed in a manner similar to the prior art framework 100 described above in relation to Figures 1 to 5. That is, the framework 100 comprises several upright members 102 and a first upper rail system 108 extending in the X and Y directions.

[0067] The framework 100 further comprises storage compartments in the form of storage columns 105 provided between the members 102, with storage containers 106 being stackable in stacks 107 within the storage columns 105.

[0068] The framework 100 can be of any size. In particular, it is understood that the framework can be significantly wider and / or longer and / or deeper than that disclosed in Figure 1. For example, the framework 100 can have a horizontal extent of greater than 700 x 700 columns and a storage depth of greater than 12 containers.

[0069] One embodiment of an automated storage and retrieval system according to the present invention will now be discussed in more detail with reference to FIGS.

[0070] 6 and 7 are schematic diagrams of a rail system 108 disposed at least partially across a framework of an automated storage and retrieval system, on which a plurality of container handling vehicles are operable to retrieve storage containers 106 from storage columns 105 arranged in a row between the upright members (and optionally horizontal members) of the framework, deliver storage containers 106 to the storage columns 105, and move storage containers 106 to and from an access station port area 510. The port area 510 is represented by two port columns 119, 120 and two buffer columns 519, 520 adjacent to the port columns 119, 120.

[0071] The number of port columns 119, 120 in the port area 510 can vary based on the type of access station. One type of access station has one port column 119, 120 that is used for both retrieving and delivering storage containers. Another type of access station has several port columns 119, 120, with some of the port columns 119, 120 provided for retrieving storage containers 106 and other port columns 119, 120 provided for delivering storage containers 106. Other types of access stations may have fewer or more port columns 119, 120, with some or all of the port columns 119, 120 being used for both retrieving and delivering storage containers 106.

[0072] Optional buffer columns 519, 520 adjacent to the port columns 119, 120 allow a container handling vehicle 106 to be ready to move into the port column 119, 120 immediately after the previous container handling vehicle has moved out of the port column 119, 120. Each access station has a limited number of buffer columns 519, 520, typically one or two buffer columns 519, 520 for each port column 119, 120. The buffer columns 519, 520 may have space to receive a container handling vehicle 106.

[0073] To monitor and control the automated storage and retrieval system 1, for example, the location of each storage container 106 within the framework 100, the contents of each storage container 106, and the movements of the container handling vehicles 201, 301, 401 so that the desired storage container 106 can be delivered to the desired location at the desired time without the container handling vehicles 201, 301, 401 colliding with one another, the automated storage and retrieval system 1 includes a central control system 500 that includes a database for tracking the storage containers 106. The central control system 500 is also in communication with the access stations and receives information from the access stations regarding the status of the port columns 119, 120 and the buffer columns 519, 520 adjacent to the port columns 119, 120. The status may include information regarding the presence of the storage container 106 in the column 105 of the access station, such as when the storage container 106 is ready to be returned to the storage column 119, 120, 519, 520. The central control system 500 performs a schedule of which storage containers 106 should be moved to the access station at any given time, it determines when the storage containers 106 must be picked up by container handling vehicles 201, 301, 401 in order for the storage containers 106 to arrive at the access station in time, and it calculates the route the storage containers 106 should take to travel to columns 119, 120, 519, 520 of the access station's port area 510. The central control system performs all of these tasks for multiple container handling vehicles 201, 301, 401 simultaneously, repeating the calculations as often as necessary.

[0074] In the prior art, as described with reference to FIG. 5 , if there are no valid target locations, i.e., available port columns 119, 120, or if there are no available buffer columns 519, 520 in the case where delivery is within a predetermined time and the port columns are occupied, the central control system 500 will not move the storage container 106 toward the port area 510 of the access station. When the central control system 500 has a storage container 106 on a container handling vehicle 201, 301, 401 scheduled for the port area 510, it checks whether the storage container 106 is too far from the port area 510 to be there in time. The central control system 500 will then instruct the container handling vehicle 201, 301, 401 to deliver the storage container 106 to a storage column 105 closer to the port area 510. The goal is to move the storage containers 106 that are far away and bring them closer to the port area 510 earlier. The container handling vehicle 201, 301, 401 will then be assigned to another task, where the storage container 106 located closer to the port area 510 will be assigned to another container handling vehicle 201, 301, 401 for later movement to the port area 510.

[0075] In one embodiment of the present invention, the central control system 500 enables movement of storage containers 106 toward the port area 510 without involving available ports or buffer columns 119, 120, 519, 520 in the port area 510, and enables routing of the storage containers 106 through temporary target locations or virtual buffer locations 610, 710 on the rail system 108.

[0076] 8 is an exemplary flow chart of a method 800 in accordance with one embodiment of the present invention. Method 800 is implemented in the automated storage and retrieval system described with reference to the figures, particularly FIGS. 1, 6 and 7. This is carried out by M1.

[0077] In a first step 801, the central control system 500 assigns a task to one of the plurality of container handling vehicles 201, 301, 401 to retrieve a storage container 106 from one of the storage columns 105 and deliver the storage container 106 to the port area 510. The assignment may be performed as part of a routing optimization process involving the plurality of storage container handling vehicles 201, 301, 401 and the plurality of storage containers 106. The routing optimization process may use the A* algorithm.

[0078] In a next step 802 , the central control system 500 commands the storage container handling vehicles 201 , 301 , 401 to retrieve the storage container 106 from the storage column 105 .

[0079] In a next step 803 , which may be integrated with the routing optimization step of the first step 801 , the central control system 500 determines virtual buffer locations 610 , 710 on the rail system 108 between the storage column 105 and the port area 510 .

[0080] 6, the step of determining a virtual buffer location on the rail system includes defining the virtual buffer location 610 as any storage column within a first predetermined radius 530 of one of the columns 119, 120, 519, 520 of the port area 510 as the virtual buffer location 610. In this case, the routing optimization process optimizes the route with any storage column within the first predetermined radius 530 of the columns 119, 120, 519, 520 as the target location.

[0081] 7, determining a virtual buffer location on the rail system 108 includes selecting a storage column 105 close to the port area 510 to be the virtual buffer location 710, the storage column 105 having space to receive the storage container 106. Proximity to the port area 510 may be evaluated by a temporal criterion (e.g., "temporal proximity") or a spatial criterion (e.g., "spatial proximity"). In this case, the routing optimization process optimizes the route using the virtual buffer location 710 as the target location.

[0082] 7, determining a virtual buffer location on the rail system 108 includes selecting a storage column 105 that is closest to a port area 510 that has space to receive a storage container 106 to be the virtual buffer location 710. Proximity to the port area 510 may be evaluated by a temporal criterion (e.g., "temporal proximity") or a spatial criterion (e.g., "spatial proximity"). In this case, the routing optimization process optimizes the route using the virtual buffer location 710 as the target location.

[0083] In a next step 804, the central control system 500 commands the container handling vehicles 201, 301, 401 to move the storage container 106 towards the selected virtual buffer location 610, 710.

[0084] In next steps 805 and 806, while the container handling vehicles 201, 301, 401 are moving the storage containers 106 towards the virtual buffer locations 610, 710, the central control system 500 is repeatedly receiving data on the current location of the storage containers 106 and / or container handling vehicles 201, 301, 401 on the rail system 108 and the current availability of access stations. These steps may be integrated with the routing optimization step of the first step 801 and are performed as frequently as required.

[0085] The central control system 500 database has information on the location of all storage containers 106. The central control system 500 is also notified by the access station when a storage container 106 is ready to be retrieved from the port columns 119, 120 of the port area 510 of the access station.

[0086] If the current location of the storage container 106 is different from the virtual buffer location 610, 710 and a column 119, 120, 519, 520 of the port area 510 is available, the central control system 500 instructs the container handling vehicle 201, 301, 401 carrying the storage container 106 to move the storage container 106 to the port column 119, 120 or the buffer column 519, 520. That is, when the port area 510 of the access station becomes available while the storage container 106 is moving toward the virtual buffer location 610, 710, the storage container 106 is rerouted from the virtual buffer location 610, 710. Once the storage container 106 is in the access station's port area 510, the central control system 500 commands the container handling vehicles 201, 301, 401 to deliver the storage container 106 into one of the columns 119, 120, 519, 520 of the access station's port area 510. The container handling vehicles 201, 301, 401 will then deliver the storage container 106 to the column 119, 120, 519, 520 and move away to be assigned to other tasks.

[0087] If the storage container 106 is at the virtual buffer location 610, 710 before the port area 510 becomes available, the next step 808 is to wait at the virtual buffer location 610, 710 for the port area 510 to become available, i.e., if the current location of the storage container 106 is at the virtual buffer location 610, 710 and columns 119, 120, 519, 520 of the port area 510 are available, instruct the container handling vehicle 201, 301, 401 to move to columns 119, 120, 519, 520 of the port area 510, and instruct the container handling vehicle 201, 301, 401 to deliver the storage container 106 into columns 119, 120, 519, 520 of the port area 510. These steps may be integrated with the routing optimization step of the first step 801 and are performed as frequently as necessary.

[0088] If the virtual buffer location 610 is within the first predetermined radius 530 of the columns 119, 120, 519, 520 of the port area 510, there are multiple available virtual buffer locations 610. Because the routing optimization step is performed frequently, the container handling vehicle 201, 301, 401 holding the storage container 106 may move around. In one embodiment, the storage container 106 is allowed to move outside the first predetermined radius 530 of the columns 119, 120, 519, 520 of the port area 510 to a virtual buffer location 611 within the second predetermined radius 540 of the columns 119, 120, 519, 520 of the port area 510. The container handling vehicle 201, 301, 401 is instructed to move the storage container 106 to the virtual buffer location 611 within the first predetermined radius 540 when the storage container is at a location 612 outside the second predetermined radius 530.

[0089] , Waiting too long with the storage container 106 in the container handling vehicle 201, 301, 401 at the virtual buffer location 610, 710 wastes the resources of the container handling vehicle, so unnecessary waiting should be avoided.

[0090] In step 809, if the current location of the storage container 106 is at the virtual buffer location 610, 710 and an access station is not available, the central control system 500 commands the container handling vehicle 201, 301, 401 to deliver the storage container 106 to the virtual buffer location 610, 710. The storage container 106 is then stored in a storage column 105 below the designated virtual buffer location 610, 710 on the rail system, or above the virtual buffer location 610, 710 if the container handling vehicle has placed the storage container 106 at the height (z=0) of the rail system.

[0091] If the virtual buffer location 610 is within a first predetermined radius 530 of columns 119, 120, 519, 520 of the port area 510, there are multiple available virtual buffer locations 610. Because the routing optimization step is performed frequently, the container handling vehicle 201, 301, 401 holding the storage container 106 may move around. In step 809, if the current location of the storage container 106 is at the virtual buffer location 610 and an access station is not available, the control system 500 instructs one container handling vehicle 201, 301, 401 to deliver the storage container 106 to the virtual buffer location 610′, 611, 612.

[0092] In one embodiment, step 809 instructs the container handling vehicle 201, 301, 401 to deliver the storage container 106 to the virtual buffer location 610, 610', 611, 612, 710 when the deadline for delivering the storage container 106 into the column 119, 120, 519, 520 of the port area 510 exceeds the deadline threshold.

[0093] In one embodiment, step 809 determines to instruct the container handling vehicle 201, 301, 401 to deliver the storage container 106 to the virtual buffer location 610, 610' 611, 612, 710 when the access station has been idle for a time exceeding an idle threshold. The idle threshold may be determined automatically by the central control system 500 based on statistical analysis of the automated storage and retrieval system 1.

[0094] In one embodiment, the present invention may be provided in the form of a computer program product for the central control system 500. The computer program product comprises instructions that, when executed on the central control system, perform the steps of the method 800.

[0095] In the foregoing description, various aspects of the delivery vehicle and automated storage and retrieval system according to the present invention have been described with reference to illustrative embodiments. For purposes of explanation, specific numbers, systems, and configurations have been set forth to provide a thorough understanding of the system and its operation. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiments, as well as other embodiments of the system, will be apparent to those skilled in the art to which the disclosed subject matter pertains, and are deemed to be within the scope of the present invention. [Explanation of symbols]

[0096] List of Reference Numbers 1. Prior Art Automated Storage and Retrieval Systems 100 Framework Structure 102 Upright members of framework structures 104 Storage Grid 105 Storage Column 106 Storage Container 106' Specific location of storage container 107 stacks 108 Rail System 110 Parallel rail in the first direction (X) 112 Access opening 119 First Port Column 120 Second Port Column 201 Prior Art Container Handling Vehicles 201a Vehicle body of container handling vehicle 201 201b Drive means / wheel arrangement / first set of wheels in first direction (X) 201c Drive means / wheel arrangement / second set of wheels in second direction (Y) 301 Prior Art Cantilever Container Handling Vehicle 301a Vehicle body of container handling vehicle 301 301b Drive means / first set of wheels in first direction (X) 301c Drive means / second set of wheels in second direction (Y) 304 Grasping Device 401 Prior Art Container Handling Vehicles 401a Vehicle body of container handling vehicle 401 401b Drive means / first set of wheels in first direction (X) 401c Drive means / second set of wheels in second direction (Y) 404 Grasping Device 404a Lift Band 404b Grip 404c Guide pin 404d lift frame 500 Control System X first direction Y Second direction Z third direction 510 Access Station Port Area 519 First Buffer Column 520 Second Buffer Column 610 Virtual Buffer Position 610' Virtual buffer position 611 Virtual Buffer Position 613 Return to virtual buffer position 610 710 Virtual Buffer Position 800 Methods for Moving Storage Containers 801 Assign container handling vehicles to access stations to retrieve storage containers 802 Order container handling vehicles to retrieve stored containers 803 Determine the virtual buffer position 804 Command container handling vehicles to move to virtual buffer locations 805 Virtual buffer position? 806 Access Station Available? 807 Command container handling vehicles to move to access station 808 access station available? 809 Put in virtual buffer? 810 Command container handling vehicles to place storage containers in virtual buffers

Claims

1. 1. A method for moving a storage container (106) using one of a plurality of container handling vehicles (201, 301, 401) on a rail system (108) arranged at least partially across a framework (100) of an automated storage and retrieval system (1), wherein the plurality of container handling vehicles (201, 301, 401) on the rail system (108) are operable to retrieve a storage container (106) from and deliver the storage container (106) into storage columns (105) arranged in a row between uprights (102) of the framework (100), and to move the storage container (106) to and from a port area (510) of an access station, the method comprising the steps of: - assigning a task to one of said plurality of container handling vehicles (201, 301, 401) to retrieve a storage container (106) from one of said storage columns (105) and deliver said storage container (106) to said port area (510); - instructing said container handling vehicle (201, 301, 401) to retrieve said storage container from said one of said storage columns (105); - determining a virtual buffer location (610, 710) on said rail system (108) between said storage column (105) and said port area (510); - instructing the container handling vehicle (201, 301, 401) to move the storage container (106) towards the virtual buffer location (610, 710) on the rail system (108); - repeatedly receiving data on the current location of said storage containers (106) on said rail system (108) and the current availability of said access stations (510); - instructing the container handling vehicle (201, 301, 401) to move the storage container (106) to a column (119, 120, 519, 520) of the port area (510) if the current location of the storage container (106) is different from the virtual buffer location (610, 710) and a column (119, 120, 519, 520) of the port area (510) is available; - instructing said container handling vehicles (201, 301, 401) to deliver said storage containers (106) into said columns (119, 120, 519, 520) of said port area (510); is performed by a central control system (500) in communication with said access station (510) and by a local controller in each of said plurality of container handling vehicles (201, 301, 401).

2. 2. The method of claim 1, wherein the step of determining the virtual buffer location on the rail system includes defining the virtual buffer location as any storage column within a first predetermined radius of one of the columns of the port area as the virtual buffer location.

3. 2. The method of claim 1, wherein the step of determining the virtual buffer location on the rail system includes selecting a storage column (105) close to the port area (510) to be the virtual buffer location (710), the storage column (105) having space to receive the storage container (106).

4. 2. The method of claim 1, wherein the step of determining the virtual buffer location on the rail system includes selecting the storage column (105) closest to the port area (510) having space to receive the storage container (106) to be the virtual buffer location (710).

5. - instructing the container handling vehicle (201, 301, 401) to move to a column (119, 120, 519, 520) of the access station (510) if the current location of the storage container (106) is at the virtual buffer location (610, 710) and the column (119, 120, 519, 520) of the port area (510) is available; - commanding said container handling vehicles (201, 301, 401) to deliver said storage containers (106) into said columns (119, 120, 519, 520) of said port area (510); 10. The method of any one of the preceding claims, comprising:

6. 10. The method of claim 9, further comprising: determining, when the current location of the storage container (106) is at the virtual buffer location (610, 710) and the access station is not available, to instruct the container handling vehicle (201, 301, 401) to deliver the storage container to the virtual buffer location (610, 710).

7. 7. The method of claim 2, or any one of claims 5 or 6 when dependent on claim 2, comprising determining to instruct the container handling vehicle (201, 301, 401) to deliver the storage container to a virtual buffer location (610', 611, 612) other than the virtual buffer location (610) when the current location of the storage container (106) is at the virtual buffer location and the access station is not available.

8. 8. The method of claim 6 or 7, comprising instructing the container handling vehicle (201, 301, 401) to deliver the storage container (106) to the virtual buffer location (610, 610′, 611, 612, 710) when a deadline for delivering the storage container (106) into a column (119, 120, 519, 520) of the port area (510) exceeds a deadline threshold.

9. 9. The method of claim 6, further comprising instructing the container handling vehicle (201, 301, 401) to deliver the storage container (106) to the virtual buffer location (610, 610', 611, 612, 710) when the access station (510) has been idle for a time exceeding an idle threshold.

10. An automated storage and retrieval system (1), comprising: a framework structure (100) comprising upright members (102); a rail system (108) arranged at least partially across said framework structure (100); - storage columns (105) arranged in rows between the uprights (102) of the framework (100); an access station comprising a port area (510); a plurality of container handling vehicles (201, 301, 401), the plurality of container handling vehicles (201, 301, 401) operable to retrieve and deliver storage containers (106) from and into the storage columns (105), and to move the storage containers (106) to and from the port area (510) of the access station, each of the plurality of container handling vehicles (201, 301, 401) comprising a local controller; a central control system (500) operable to communicate with said access station (510) and said local controllers in each of said plurality of container handling vehicles (201, 301, 401), said central control system (500) comprising: - assigning a task to one of said plurality of container handling vehicles (201, 301, 401) to retrieve a storage container (106) from one of said storage columns (105) and deliver said storage container (106) to said port area (510); - commanding said container handling vehicle (201, 301, 401) to retrieve said storage container from said one of said storage columns (105); - determining a virtual buffer location (610, 710) on the rail system (108) between the storage column (105) and the port area (510); - commanding said container handling vehicle (201, 301, 401) to move said storage container (106) towards said virtual buffer location (610, 710); - repeatedly receiving data on the current location of said storage containers (106) on said rail system (108) and the current availability of said access stations (510); - instructing the container handling vehicle (201, 301, 401) to move the storage container (106) to a column (119, 120, 519, 520) of the port area (510) if the current location of the storage container (106) is different from the virtual buffer location (610, 710) and the column (119, 120, 519, 520) of the port area (510) is available; - commanding said container handling vehicles (201, 301, 401) to deliver said storage containers (106) into said columns (119, 120, 519, 520) of said port area (510); a central control system (500) adapted to perform the An automated storage and retrieval system (1) comprising:

11. 11. The system of claim 10, wherein the system is adapted to determine the virtual buffer location on the rail system by defining the virtual buffer location as any storage column (105) within a first predetermined radius (530) of one of the columns (119, 120, 519, 520) of the port area (510) as the virtual buffer location.

12. 11. The system of claim 10, wherein the system is adapted to determine the virtual buffer location on the rail system by selecting a storage column (105) close to the port area (510) to be the virtual buffer location (710), the storage column (105) having space to receive the storage container (106).

13. 11. The system of claim 10, wherein the system is adapted to determine the virtual buffer location on the rail system by selecting the storage column (105) closest to the port area (510) having space to receive the storage container (106) to be the virtual buffer location (710).

14. The system comprises: - instructing the container handling vehicle (201, 301, 401) to move to a column (119, 120, 519, 520) of the access station (510) if the current location of the storage container (106) is at the virtual buffer location (610, 710) and the column (119, 120, 519, 520) of the port area (510) is available; - commanding said container handling vehicles (201, 301, 401) to deliver said storage containers (106) into said columns (119, 120, 519, 520) of said port area (510); The system according to any one of claims 10 to 13, adapted to:

15. The system of any one of claims 10 to 14, wherein the system is adapted to determine, when the current location of the storage container (106) is at the virtual buffer location (610, 710) and the access station is not available, to instruct the container handling vehicle (201, 301, 401) to deliver the storage container to the virtual buffer location (610, 710).

16. The system of claim 11, or any one of claims 14 or 15 when dependent on claim 11, wherein the system is adapted to determine, when the current location of the storage container (106) is at the virtual buffer location and the access station is not available, to instruct the container handling vehicle (201, 301, 401) to deliver the storage container to a virtual buffer location (610', 611, 612) other than the virtual buffer location (610).

17. 18. The system of claim 16 or 17, wherein the system is adapted to instruct the container handling vehicle (201, 301, 401) to deliver the storage container (106) to the virtual buffer location (610, 610′, 611, 612, 710) when a deadline for delivering the storage container (106) into a column (119, 120, 519, 520) of the port area (510) exceeds a deadline threshold.

18. 19. The system of claim 16, wherein the system is adapted to instruct the container handling vehicle (201, 301, 401) to deliver the storage container (106) to the buffer location (610, 610', 611, 612, 710) when the access station (510) has been idle for a time exceeding an idle threshold.

19. A computer program product for the central control system (500) in the system of claims 10 to 18, said computer program product comprising instructions for performing the method of claims 1 to 9 when executed on said control system.

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