The present invention relates to an automated storage and retrieval system for storage and retrieval of storage containers handled by container handling vehicles, and more specifically to a method, system and computer program for controlling movement of a plurality of container handling vehicles in physical connection.
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 201a,301a, and first and second sets of wheels 201b,301b,201c,301c which enable the lateral movement of the container handling vehicles 201,301 in the X direction and in the Y direction, respectively. In
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 are shown in
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
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 are referred to as storage cells. 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 201a as shown in
The central cavity container handling vehicles 201 shown in
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 in which the wheels of the vehicles run. 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.
WO2018/146304, 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
In
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.
When a storage container 106 stored in one of the columns 105 disclosed in
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 121 which typically is computerized and which typically comprises a database for keeping track of the storage containers 106.
WO2019/086237, describes a storage system comprising a multi trolley vehicle for transporting storage containers. The multi trolley vehicle comprises a plurality of trolleys coupled to each other and a first and second drive vehicles.
CN211033920, describes a material storage system comprising a push-pull assembly for driving a skip car to move along a circulating conveying line.
US2018162639, describes a storage system comprising diverting means adapted to divert containers from a moving means to a storage positions and from the storage positions to the moving means.
WO2017/121512, describes a storage system, where the container handling vehicles are arranged with sensors that can detect the location of the vehicle, and proximity sensor to detect the location of nearby vehicles, and communicate that information to the control system. The control system communicates with a plurality of container handling vehicles and commands the container handling vehicles to form a “train” of vehicles, i.e. a plurality of container handling vehicles proximately arranged in series and arranged to move with one another in tandem. The assembly of the train is accomplished with help of the sensors in the container handling vehicles, by the control system's knowledge about the container handling vehicles' relative positions, or a combination of both. However, the position of a container handling vehicle on the rail system is not known with certainty until it has passed a track crossing, after which the position of the container handling vehicle may be transmitted to the control system which processes this information. This results in a delay due to the command being relayed through, and processed in, the control system, and in insufficient positioning information for effective train driving for the container handling vehicles. Various methodologies to mitigate this problem is described, such as adding proximity sensors on each container handling vehicle or physical coupling such as latches, magnetic coupling etc.
The delay is particularly problematic around ports and similar where the container handling vehicles has a tendency to queue up. This is illustrated with reference to
The present invention regards a solution for queue driving of container handling vehicles in order to save time around ports avoiding the need to wait for the confirmation messages and instructions to move.
The invention hence solves the problem by letting the container handling vehicles 501, 502 queue up mechanically. The container handling vehicles 501, 502 drives bumper to bumper without actually having anything holding them together. They stay bumper to bumper by having the last container handling vehicle drive a little faster than the front container handling vehicles, and by letting the front container handling vehicle brake a little more than the last container handling vehicle.
The solution may also be used for longer trains, in which case a third container handling vehicle moves faster than the second container handling vehicle, a fourth container handling vehicle moves faster than the third container handling vehicle and so on.
The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention.
In one aspect he present invention relates to a method of controlling movement of a plurality of container handling vehicles on a rail system arranged at least partially across a top of framework structure of an automated storage and retrieval system, on which rail system the plurality of container handling vehicles are operable to handle storage containers, and where the following steps are performed by a control system which is in communication with a local controller in each container handling vehicle,
An advantage of this invention is that it allows a plurality of container handling vehicles to queue up mechanically in order to save time around ports avoiding the need to wait for the confirmation messages and instructions to move.
The target position may be any position on the rail system. The target position may be a final position on the rail system, such as port position, or the target position may be any intermediate positions on its way to a final position. The vehicle may for example be instructed to move to a first position on the rail system where the vehicle waits for another vehicle to pass, before getting instructions to move to a second position in step-by-step instructions.
Instructing to apply a push force may comprise instructing the second container handling vehicle to exceed a non-pushing force required for movement of the second container handling vehicle. The non-pushing force may be exceeded by 2-25%, preferably 2-10%, or most preferably 3-8%.
The push force and the non-pushing force may be determined by measuring power usage of the second container handling vehicle.
Instructing to apply a push force may comprise instructing the second container vehicle to move according to a movement vector exceeding a corresponding movement vector of the first container handling vehicle in the first direction. The corresponding movement vector of the first container handling vehicle in the first direction may be exceeded by 2-25%, preferably 2-10%, or most preferably 3-8%.
In one embodiment, the method may further comprise after determining that the first container handling vehicle has not moved within a predetermined time interval, stopping applying the push force on the first container handling vehicle. The determination that the first container handling vehicle has not moved within the predetermined time interval may comprise determining with the second container handling vehicle that the second container handling vehicle has not moved within the predetermined time interval.
In one embodiment, the method may further comprise initiating an emergency stop of the second container handling vehicle after determining, with the second container handling vehicle, a deceleration above a predefined threshold.
In one embodiment, the method may further comprise upon determining with the second container handling vehicle that the first container handling vehicle is moving, increasing the push force on the first container handling vehicle.
In a second aspect, the present invention also relates to a an automated storage and retrieval system comprising a plurality of container handling vehicles on a rail system arranged at least partially across a top of framework structure of the automated storage and retrieval system, on which rail system the plurality of container handling vehicles are operable to handle storage containers, and a control system adapted to be in communication with the local controller in each controller handling vehicle, the control system further being adapted to perform the steps of:
Instructing to apply a push force may comprise instructing the second container handling vehicle to exceed a non-pushing force required for default movement of the second container handling vehicle. The non-pushing force may be exceeded by 2-25%, preferably 2-10%, or most preferably 3-8%.
The push force and the non-pushing force may be determined by measuring power usage of the second container handling vehicle.
Instructing to apply a push force may comprise instructing the second container vehicle to move according to a movement vector exceeding a corresponding movement vector of the first container handling vehicle in the first direction. The corresponding movement vector of the first container handling vehicle in the first direction may be exceeded by 2-25%, preferably 2-10%, or most preferably 3-8%.
The second container handling vehicle may be adapted to stop applying the push force on the first container handling vehicle after determining that the first container handling vehicle has not moved within a predetermined time interval.
The second container handling vehicle may be adapted to determine that the first container handling vehicle has not moved within the predetermined time interval by determining that the second container handling vehicle has not moved within the predetermined time interval.
In one embodiment, the system may further be adapted to initiate an emergency stop of the second container handling vehicle after determining, with the second container handling vehicle, a deceleration above a predefined threshold.
The second container handling vehicle may be adapted to upon determining that the first container handling vehicle is moving, increasing the push force on the first container handling vehicle.
The contact areas between the first container handling vehicle and the second container handling vehicle may provided with a low friction protection surface.
In a third aspect, the present invention also relates to a computer program product for a control system described above, wherein the computer program product comprising instructions that when performed on the control system performs the method described above.
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:
In the following, embodiments of the invention will be discussed in more detail 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
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
The present invention relates to a system and method that allows a plurality of container handling vehicles to form a “train” of vehicles, i.e. a plurality of container handling vehicles arranged in series or queues and arranged to move with one another in tandem. This save time around ports avoiding the need to wait for the confirmation messages and instructions to move. Compared with the prior art method described with reference to
One embodiment of the automated storage and retrieval system according to the invention will now be discussed in more detail with reference to
In
Then in
In
In
In one embodiment the second container handling vehicle 502 is instructed to apply a push force exceeding a non-pushing force required for movement of the second container handling vehicle 502. The non-pushing force may be the inertia to movement that has to be overcome before the second container handling vehicle 502 starts to move along the rail system from stationary, or the force required to keep the second container handling vehicle 502 to move along the rail system by itself. The non-pushing force may be given by the total weight of the second container handling device 502 and/or other driving configurations of the second container handling device 502.
When the push force is defined as a force exceeding the non-pushing force, the second container handling vehicle 502 may dynamically adjust the push force based on feedback so that the amount of push force is kept within a tight range of just nudging the first container handling device 501 and as it moves adjusting the output of the second container handling vehicle to keep within that range. The second container handling vehicle 502 may determine the push force and the non-pushing force by measuring power usage of the second container handling vehicle 502. The power use may provide the feedback to dynamically adjust the amount of push force.
The non-pushing force may be exceeded by 2-25%, 2-10% or 3-8% to provide the necessary push force.
In another embodiment, the push force is defined by instructing the second container handling vehicle 502 to move according to a movement vector in the direction of the first container handling vehicle 501. The movement vector of the second container handling vehicle 502 exceeds a corresponding movement vector of the first container handling vehicle 501:
Acceleration of the second container handling vehicle 502>Acceleration of the first container handling vehicle 501.
Speed of the second container handling vehicle 502>Speed of the first container handling vehicle 501.
Deceleration of the second container handling vehicle 502<Deceleration of the first container handling vehicle 501.
The movement vector of the first container handling vehicle 501 in the first direction may be exceeded by 2-25%, 2-10% or 3-8% to provide the necessary push force.
The first and second container handling vehicle 501, 502 are configured to allow more unexpected behaviour when driving in queue formation than when driving alone before reporting errors to the control system. Still, if the first container handling vehicle 501 fails, the second container handling vehicle 502 should be instructed by the control system to initiate an emergency stop. Errors in the in the communication system, delays in the control system, delays in the communications system, crashes on the rail system etc. may prohibit the control system to instruct the container handling vehicle 502 to stop. The second container handling vehicle 502 may therefore be adapted to initiate an emergency stop of the second container handling vehicle 502 after determining, with the second container handling vehicle 502, a deceleration above a predefined threshold. This determination may be based on measurements of the push force using power usage, external sensor or other means of measuring force.
In one embodiment the queue of container handling vehicles may comprise more than two container handling vehicles 501, 502. In that case a third container handling vehicle applies a larger push force than the second container handling vehicle 502, a fourth container handling vehicle applies a larger push force than the third container handling vehicle and so on for each container handling vehicle further back in the queue of container handling vehicles.
A plurality of container handling vehicles may also drive in queue for a first distance, and then split into several smaller queues. Container handling vehicles in front of the container handling vehicles that split off may continue at the current speed, whereas container handling vehicles behind the container handling vehicles that split off will have to slow down. After splitting the smaller queues will reconfigure and continue as described above.
In the preceding description, various aspects of the container handling 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 claims.
Prior art (
Number | Date | Country | Kind |
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20201251 | Nov 2020 | NO | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2021/081559 | 11/12/2021 | WO |