Routing of container handling vehicles of an automated storage and retrieval system

Abstract

A method, control system, and computer program are provided for routing and rerouting container transport vehicles carrying storage containers in an automated storage and retrieval system comprising a frame structure. The method includes the following steps, performed by the control system when the computer program is executed: running a multi-agent pathfinding algorithm (MAPF) in the control system to establish and assign routes for the container transport vehicles on a track system from their current location to a destination location; determining how far the container transport vehicles can travel on a first portion of the assigned route within a set time interval, the first portion being shorter than the assigned route to the destination; locking the first portion of the assigned route that the container transport vehicles can travel within the set time interval; instructing the container transport vehicles to move from their current location to the destination location on the assigned locked route; and repeating the above steps.

Description

Technical Field

[0001] The present invention relates to an automated storage and retrieval system for storage containers carried by container handling vehicles operating on a grid-based track system of storage and retrieval system, and more specifically, to a method, system, and computer program for routing and rerouting container handling vehicles according to available routes on the track system. Background Technology

[0002] Figure 1 illustrates a typical prior art automated storage and retrieval system 1, which has a frame structure 100 and a container transport vehicle 201, also known as a robot, operating on the system 1.

[0003] The frame structure 100 includes upright members 102, horizontal members 103, and storage volumes comprising storage columns 105 arranged in rows between the upright members 102 and the horizontal members 103. Within these storage columns 105, storage containers 106, also referred to as boxes, are stacked one on top of the other to form a stack 107. Members 102 and 103 are typically made of metal, such as extruded aluminum profiles.

[0004] The frame structure 100 of the automated storage and retrieval system 1 includes a track system 108 arranged across the top of the frame structure 100, on which multiple container transport vehicles 201 operate to raise storage containers 106 from storage columns 105 and lower storage containers 106 into storage columns 105, and also transport storage containers 106 above storage columns 105.

[0005] The track system 108 includes a first set of parallel tracks 110 arranged to guide the container transport vehicle 201 to move along a first direction X through the top of the frame structure 100; and a second set of parallel tracks 111 arranged perpendicular to the first set of tracks 110 to guide the container transport vehicle 201 to move in a second direction Y perpendicular to the first direction X.

[0006] Figure 1 also shows a first track 110a in the first direction X, a second track 110b in the first direction X, a first track 111a in the second direction Y, and a second track 111b in the second direction Y. The container transport vehicle 201 moves laterally above the storage column 105, that is, it moves in a plane parallel to the horizontal XY plane.

[0007] The type of container transport vehicle 201 used can be any type known in the art, such as one of the automated container transport vehicles disclosed in WO2014 / 090684A1 or WO2015 / 193278A1 that has a footprint covering one or two storage columns 105. The track system 108 can be arranged in a single and / or dual-track configuration.

[0008] Storage containers 106 are stored in columns 105, which define a third direction Z orthogonal to a first direction X and a second direction Y. Container transport vehicles 201 access the storage containers 106 through access openings 112 in a track system 108, i.e., the track system 108 is arranged on a frame structure 100, which defines the circumference of each access opening 112 at the top of each storage column 105. Upright members 102 of the frame structure 100 are used to guide the storage containers as they are removed from and lowered into the columns 105. The stack 107 of the storage containers 106 is generally self-supporting.

[0009] The storage volume of the frame structure 100 is typically referred to as grid 104, and the possible storage locations within the storage columns 105 of this grid are referred to as storage cells. Each storage column 105 can be identified by its position in the X and Y directions, while each storage cell can be identified by its container number in the X, Y, and Z directions.

[0010] In the frame structure 100, most columns 105 are storage columns 105, that is, columns 105 in which storage containers 106 are stored in the stack 107. However, some columns 105 may have other purposes.

[0011] In Figure 1, columns 119 and 120 are dedicated columns for container transport vehicle 201 to unload and / or pick up storage containers 106 so that they can be transferred to access stations (not shown) that allow access to storage containers 106 from outside the frame structure 100 or to remove or move them into the frame structure 100. Access stations are typically pick-up or storage stations for removing products from or placing products into storage containers 106.

[0012] In this art, columns used for moving storage containers into and out of a storage system are generally referred to as port columns 119, 120 or transfer columns. Storage containers are transferred to and from port columns 119, 120 via ports 119', 120', which are typically located at the ends of port columns 119, 120; that is, where storage containers enter or leave port columns 119, 120. Ports may also be located in other locations, such as the middle or ground layer of port columns 119, 120.

[0013] The transport and transfer of storage container 106 to the access station can be in any direction, i.e., horizontal, inclined, and / or vertical. For example, storage container 106 can be placed in random or dedicated column 105 within frame structure 100 and then picked up by any container transport vehicle 201 and transported to port columns 119, 120 for further transport to the access station. Note that the term "inclined" refers to the transport of storage container 106 having a general transport direction somewhere between horizontal and vertical.

[0014] In Figure 1, for example, the first port column 119 may be a dedicated unloading port column, in which the container transport vehicle 201 can unload the storage container 106 to be transported to the access or transfer station, and the second port column 120 may be a dedicated pick-up port column, in which the container transport vehicle 201 can pick up the transported storage container 106 from the access or transfer station.

[0015] When operating the automated storage and retrieval system 1, each container transport vehicle 201 is given a task by receiving instructions. For example, the task could be to retrieve a specific storage container 106 from storage column 105 and deliver it at port column 119 for further transport to the access station, or to move storage container 106 from one storage unit to another. This means instructing each container transport vehicle 201 to travel along a predetermined route on track 111 from its current location to a target location.

[0016] When a specific storage container 106 is to be retrieved from one of the columns 105 shown in Figure 1, a task is assigned to one of the container transport vehicles 201, instructing it to retrieve the target storage container 106 from its location and transport it to port 119' of port column 119. This operation involves moving the container transport vehicle 201 to a position above the storage column 105 where the storage container 106 is located, using the lifting device (not shown) of the container transport vehicle 201 to retrieve the storage container 106 from the storage column 105, and transporting the storage container 106 to port 119' of port column 119.

[0017] If the target storage container 106 is located deep within the stack 107, i.e., one or more other storage containers 106 are located above the target storage container 106, the operation also involves temporarily moving the storage container placed above it before lifting the target storage container 106 from the storage column 105. This step, sometimes referred to in the art as "digging," can be performed using the same container transport vehicle 201 subsequently used to transport the target storage container to the unloading port column 119, or by one or more other cooperating container transport vehicles 201. Alternatively or additionally, the automated storage and retrieval system 1 may have a container transport vehicle 201 specifically for the task of temporarily removing storage containers from the storage column 105. Once the target storage container 106 has been removed from the storage column 105, the temporarily removed storage container 106 can be repositioned back into the original storage column 105. However, the removed storage container 106 may alternatively be repositioned to another storage column 105.

[0018] When storage container 106 is to be stored in one of the columns 105, one of the container transport vehicles 201 is instructed to pick up storage container 106 from port 120' of port column 120, transfer the storage container from the access or transfer station, and transport it to a position above the storage column 105 where it is to be stored. After removing any storage container located at or above the target position within the storage column stack 107, the container transport vehicle 201 positions storage container 106 in the desired position. The removed storage container 106 can then be lowered back into storage column 105 or repositioned into another storage column.

[0019] The position of each storage container 106 within the frame structure 100, as well as the position and movement of each container transport vehicle 201 operating on the storage and retrieval system, are continuously monitored and controlled by the control system 500 and a reference to the contents of each storage container 106, so that the desired storage container 106 can be delivered to the desired location at the desired time, and the container transport vehicles 201 do not collide with each other.

[0020] Figure 2 An example of a typical control system 500 is shown. The control system 500 is adapted to transmit operating and movement commands to the vehicle controller 230 in each container transport vehicle 201 to control all movement and operations on the storage and retrieval system 1. The control system 500 instructs each vehicle 201 to store or retrieve storage container 106. The current position of each vehicle 201 is transmitted from vehicle 201 to the control system 500, enabling it to control the movement of all vehicles 201 on the track system 108 in an optimal manner without queuing or collisions.

[0021] In the example shown, the control system 500 includes a main controller 220, a database 210, a routing planner 200, and a transmitter / receiver 225 for transmitting instructions to each container delivery vehicle 201.

[0022] The database keeps track of the location of storage container 106 at all times, as well as the storage container 106 to be transported, i.e., the storage container 106 to be retrieved or stored in storage grid 104. The routing planner 200 is adapted to find the optimal route for the container transport vehicle 201.

[0023] The main controller 220 is adapted to coordinate information from the database 210 and the route planner, and is adapted to generate operating instructions for each container transport vehicle 201, for example, based on the transport of storage containers and the route followed on the track system 108 according to the input from the route planner 200.

[0024] The control system 500 communicates with the central computer, through which orders and tasks are transmitted to the control system 500.

[0025] Typically, the automated storage and retrieval system 1 operates in conjunction with multiple container transport vehicles 201 that move storage containers from one location to another. Larger storage and retrieval systems may be equipped with hundreds of container transport vehicles 201, each of which is assigned and given a task by receiving instructions from the control system 500. For example, a task might be to retrieve a specific storage container 106 from its storage column 105, follow a route by traveling a set distance in a set direction, deliver the storage container 106 at port 119', and so on.

[0026] The control system 500 issues instructions to each container transport vehicle 201 to perform a task and follow a specific route from its current location to its target destination. The overall goal is to find the optimal route for each container transport vehicle 201 that does not conflict with others. The optimal route is typically the shortest route that does not conflict with other routes within the same time period.

[0027] Multi-agent pathfinding (MAPF) is a known algorithm in computer science and can be used to solve the problem of finding paths from the current positions to the target positions of multiple agents without conflicting with each other, while optimizing the cost function, such as the sum of the path lengths of all agents.

[0028] For the storage and retrieval system 1, container delivery vehicle 201 represents an agent. However, most MAPF algorithms are one-off algorithms that solve specific scenarios, where container delivery vehicle 201 completes its planned task along a set route from its current location to its final location before developing a new route based on the new task. Adapting these multi-agent pathfinding algorithms to dynamically changing environments, where container delivery vehicle 201 may change the type of task or objective before completing its first assigned task, or where new active container delivery vehicles 201 are operating on the storage system, is not straightforward.

[0029] By using the MAPF algorithm, multiple container delivery vehicles 201 can be routed simultaneously. However, since the MAPF algorithm has a relatively long execution time, container delivery vehicles 201 must wait while new routes are being generated.

[0030] In David Silver's 2005 paper "Cooperative pathfinding" (Proceedings of the First Articial Intelligence and Interactive Digital Entertainment Conference, AIIDE-2005, pp. 117-122), a sliding window with a defined restricted area is used for routing to find non-conflicting routes within that area in a real-time environment. However, the cooperative search for possible routes is limited to a fixed depth specified by the current window. Each agent searches for a partial route to its destination and then begins following that route. Every so often, for example, when an agent is halfway down its partial route, the window is moved forward, and a new partial route is computed. This means that the cooperative search only considers agents within the sliding window; that is, it ignores other agents outside the window that defines the restricted area. To find the direction an agent takes to its destination, an abstract search of the full depth is performed.

[0031] This invention proposes a method for routing in which a complete route from the current location of a container transport vehicle to its destination is found, but only the first portion of each route is locked within a set time frame. This method provides time-efficient routing and allows rerouting to be performed without stopping the container transport vehicle. Summary of the Invention

[0032] The object of this invention is to provide an improved method for routing and rerouting container transport vehicles as they operate on the track system of a storage and retrieval system. A new method, system, and computer program provides all container transport vehicles with more route options than before.

[0033] This is achieved by routing and rerouting container transport vehicles as frequently as possible during their journey from their current location to their destination, and by taking into account all routes taken by all container transport vehicles from their current location to their destination.

[0034] According to the method of the present invention, the route of a container transport vehicle is calculated in real time as it moves toward its destination. The container transport vehicle can be effectively rerouted to follow a new route to adapt to changes in traffic conditions, and new routes can be created for newly activated container transport vehicles.

[0035] The new method finds new routes for all container delivery vehicles in less time without requiring them to stop, and provides more route options for all container delivery vehicles. According to this method, MAPF is used to find routes to the final destination for all container delivery vehicles, but only the first part of each route is locked within a set time interval. This contrasts with existing technologies, where the entire route is locked, or where only routes for vehicles within a restricted area defined by a sliding window are evaluated, as described in the aforementioned paper by David Silver.

[0036] The new method offers more route options as container transport vehicles move along their assigned routes, by releasing the already covered portions of each route for new routes and the unlocked portions of the assigned routes.

[0037] The method of the present invention provides a fluid, ever-changing system, and MAPF not only allows this, but also allows for shorter travel times compared to previous planning algorithms because the path is blocked for less time.

[0038] The present invention is defined by a method for routing and rerouting container transport vehicles carrying storage containers in an automated storage and retrieval system comprising a frame structure forming a three-dimensional storage grid structure for storing storage containers in storage columns. The frame structure includes a grid-based track system arranged above the storage columns having a track system, the track system providing usable routes for container transport vehicles to transport and transfer storage containers to and from the storage columns, and wherein each container transport vehicle includes a first set of wheels and a second set of wheels, the first set of wheels being configured to move the vehicle along a first direction (X) of the grid-based track system, and the second set of wheels being configured to move the vehicle along a second direction (Y) of the grid-based track system, the second direction (Y) being perpendicular to the first direction (X). The movement of the container transport vehicles is controlled by a control system that determines the tasks to be performed by designated container transport vehicles, determines the destination location for performing the tasks, and the routes that the container transport vehicles will travel on the track system.

[0039] The method includes the following steps performed by the control system:

[0040] a. Run the multi-agent pathfinding algorithm MAPF in the control system to establish and assign routes for container transport vehicles from their current location to their destination location on the track system.

[0041] b. Determine how far the container transport vehicle can travel on the first part of the assigned route within a set time interval, the first part being shorter than the assigned route to the destination;

[0042] c. Lock the first part of the assigned route that the container transport vehicle can travel within a set time interval;

[0043] d. Instruct the container transport vehicle to move from its current location to its destination along the assigned locked route;

[0044] e. Repeat steps a) through d).

[0045] According to one embodiment of the method, the upper limit of the time interval set in step b) can correspond to the execution time of the control system for executing the MAPF algorithm and instructing the container transport vehicle to move according to the established route. The distance the container transport vehicle travels on the track system according to the assigned route within this time interval will be the locked portion of the complete route established by MAPF.

[0046] According to one embodiment of the method, the upper limit of the time interval set in step b) can correspond to the time elapsed for all container transport vehicles to move from their current positions to a position above the nearest storage column on a track system where the container transport vehicles can change direction.

[0047] According to one embodiment of the method, the duration of the time interval set in step b) can be set according to the size of the automated storage and / or retrieval system and the number of container transport vehicles to be included in the MAPF algorithm.

[0048] According to one embodiment of the method, the method may include a locking portion of the route allocated for the extension of a container transport vehicle that has been given priority.

[0049] According to one embodiment of the method, the method may include a portion of locking the route assigned to a container delivery vehicle that does not respond to an instruction.

[0050] According to one embodiment of the method, the locked portion of the assigned route can extend from the current location of the container transport vehicle to the destination location along the route established by the MAPF algorithm.

[0051] According to one embodiment of the method, during the execution of the MAPF algorithm, locked routes can be excluded from consideration of usable routes.

[0052] According to one embodiment of the method, the gaps between each route established by the MAPF algorithm can be adapted to the type of container transport vehicle traveling on the assigned routes.

[0053] According to one embodiment of the method, the movement of container transport vehicles can be controlled to avoid queuing problems that may occur at the destination location.

[0054] According to one embodiment of the method, if queuing problems are anticipated at the destination location, container delivery vehicles can be redirected.

[0055] According to one embodiment of the method, container delivery vehicles can be redirected to locations or routes where container delivery vehicles do not exist or are not heading.

[0056] According to one embodiment of the method, the movement of the container transport vehicle can be controlled based on the current load it carries and the status of the container transport vehicle.

[0057] The invention is further defined by a control system for controlling the routing and rerouting of container transport vehicles carrying storage containers in an automated storage and retrieval system comprising a frame structure forming a three-dimensional storage grid structure for storing storage containers in storage columns. The frame structure includes a grid-based track system arranged above the storage columns, the track system providing usable routes for container transport vehicles to transport and transfer storage containers to and from the storage columns. Each container transport vehicle includes a first set of wheels and a second set of wheels. The first set of wheels is configured to move the vehicle along a first direction (X) of the grid-based track system, and the second set of wheels is configured to move the vehicle along a second direction (Y) of the grid-based track system, the second direction (Y) being perpendicular to the first direction (X). The movement of the container transport vehicles is controlled by the control system, which determines the tasks to be performed by designated container transport vehicles, the destination location for performing the tasks, and the routes the container transport vehicles will travel on the track system.

[0058] The control system includes: a route planner for finding the optimal route for container transport vehicles; a database for keeping track of stored containers; and a main controller connected to a transmitter / receiver, wherein the control system is adapted to perform the above methods and to transmit control commands to each container transport vehicle.

[0059] The present invention is further defined by a computer program product that, when executed by a processor in the control system of an automated storage and retrieval system, performs the above-described method for effectively routing and rerouting container transport vehicles carrying storage containers in the automated storage and retrieval system. Attached Figure Description

[0060] The following figures are attached to facilitate understanding of the invention. The figures illustrate embodiments of the invention, which will now be described by way of example only, wherein:

[0061] Figure 1 is a perspective view of the framework structure of a prior art automated storage and retrieval system.

[0062] Figure 2 An example of a control system for controlling a container transport vehicle operating on an automated storage and retrieval system is shown.

[0063] Figure 3 This is a flowchart illustrating the different steps of a method for effectively routing and rerouting container transport vehicles for an automated storage and retrieval system.

[0064] Figure 4 A simple routing example based on previous and new routes is shown.

[0065] Reference

[0066] 1. Automatic storage and retrieval system

[0067] 100 Frame Structure

[0068] 102. Upright members of a frame structure

[0069] 103 Horizontal members of frame structures

[0070] 104 Storage Grid Structure

[0071] 105 Storage Columns

[0072] 106 Storage Containers

[0073] The specific location of the 106' storage container

[0074] 107 stacks

[0075] 108 orbital system

[0076] 110 Parallel orbits in the first direction (X)

[0077] 110a First track in the first direction (X)

[0078] 110b Second orbit in the first direction (X)

[0079] 111 Parallel track in the second direction (Y)

[0080] 111a First track in the second direction (Y)

[0081] 110b Second track in the second direction (Y)

[0082] 112 Access Point

[0083] 119 First Port Column

[0084] 119' First Port

[0085] 120 Second Port Column

[0086] 120' Second Port

[0087] 200 Route Planner

[0088] 201 Container Transport Vehicle

[0089] 210 Database

[0090] 220 Main Controller

[0091] 225 Transmitter / Receiver

[0092] 230 Vehicle Controller

[0093] X First Direction

[0094] Y Second Direction

[0095] Z Third Direction

[0096] 500 Control System Detailed Implementation

[0097] In the following description, the invention will be explained in more detail with reference to the accompanying drawings. However, it should be understood that the drawings are not intended to limit the invention to the subject matter depicted in the drawings.

[0098] Referring to Figure 1, a typical prior art automated storage and retrieval system 1 with a frame structure 100 is described in the background section above.

[0099] The frame structure 100 can be of any size, and it is understood that it can be wider and / or longer and / or deeper than the frame structure disclosed in Figure 1. For example, the frame structure 100 can have a horizontal range of storage columns 105 exceeding 700×700 and a storage depth for storing more than 12 stacks of storage containers 106, wherein the storage containers 106 are transported by hundreds of container transport vehicles 201 running on the track system 108.

[0100] Furthermore, the storage grid 104 can be much deeper than disclosed in Figure 1, which shows a stack of eight storage containers 106. For example, the storage grid 104 can be designed to accommodate a stack of twelve storage containers 106.

[0101] The container transport vehicle 201 can be of any type known in the art, such as any of the automated container transport vehicles disclosed in WO2014 / 090684 A1, NO317366 or WO2015 / 193278A1.

[0102] The track system 108 arranged across the top of the frame structure 100 allows the container transport vehicle 201 to move horizontally between the storage column 105 and the port it is interacting with, i.e., the port to which the storage container 106 is delivered or retrieved.

[0103] The automated storage and retrieval system 1 includes a frame structure 100 that forms a three-dimensional storage grid structure 104 with a grid-based track system 108 for storing storage containers 106 in storage columns 105. The grid-based track system 108 is arranged above the storage columns 105 with the track system 108. The track system 108 provides usable routes for container transport vehicles 201 to transport storage containers 106 to and from the storage columns 105. Each container transport vehicle 201 includes a first set of wheels and a second set of wheels. The first set of wheels is configured to move the vehicle along a first direction (X) of the grid-based track system, and the second set of wheels is configured to move the vehicle along a second direction (Y) of the grid-based track system 108, which is perpendicular to the first direction (X). The movement of the container transport vehicles is controlled by a control system 500 that determines the task to be performed by the designated container transport vehicle 201, determines the destination location for performing the task, and determines the route that the container transport vehicle 201 will travel on the track system 108.

[0104] Figure 2 An example of a control system 500 for controlling a container transport vehicle 201 according to an embodiment of the present invention is shown. In this example, the control system 500 includes a main controller 220, a database 210 for keeping track of stored containers 106, a route planner 200 for finding the optimal route for the container transport vehicles 201, and a transmitter / receiver 225 for transmitting instructions to each container transport vehicle 201. The figure shows the route planner 200 connected to the database 210. However, this may not be the case, as the route planner 200 can receive all necessary information from the main controller 220.

[0105] Typically, the control system 500 communicates with a central computer, through which commands and tasks are transmitted. The control system 500 further communicates with the vehicle controller 230 in each container transport vehicle 201 and controls the traffic flow of the container transport vehicles 201 based on input from the route planner 200. Preferably, communication is performed wirelessly, for example, via radio signals or optical signals.

[0106] Figure 3 This is a flowchart illustrating the different steps of a method 400 for effectively routing and rerouting container transport vehicles 201 of an automated storage and retrieval system 1.

[0107] The first step 410 of the method is to run the multi-agent pathfinding algorithm MAPF in the control system 500 to establish and assign routes for the container transport vehicle 201 from its current location to its destination location on the track system 108.

[0108] As an example, a task could be to pick up a specified storage container 106 and carry it to a port column located at another location. When several container transport vehicles 201 receive different tasks and destination locations, it is crucial that the routes they follow on the track system are unique for each container transport vehicle 201 to avoid collisions.

[0109] As described in the introduction, MAPF is used to find routes for simultaneously controlling traffic flows of multiple agents without conflict. In the present case, for the automated storage and retrieval system 1, the agent is the container transport vehicle 201.

[0110] The different modules of the control system 500 can be configured as a central control unit to execute and control all the different steps of the method described herein, or they can be configured to be interconnected to form independent units of the control system 500. Regarding independent modules, such as... Figure 2 As shown in the example, a module called Route Planner 200 will be a module running MAPF to find feasible routes for container delivery vehicles 201 from their current location to their destination, and to lock the first part of the route that cannot be changed. The resulting routes found for container delivery vehicles 201 are transmitted to the main controller 220, which will control each container delivery vehicle according to the established routes via transmitter / receiver 225.

[0111] MAPF can be used to find routes for all container transport vehicles 201 operating on the grid-based track system 108, or it can be used for a selected set of container transport vehicles 201.

[0112] For larger automated storage and retrieval systems 1, such as those operated by hundreds of container transport vehicles 201, one or more container transport vehicles 201 may be dedicated to performing specific tasks and operate in assigned areas where they follow preset routes on track system 108.

[0113] Another example is controlling the first group of container transport vehicles 201 according to a MAPF in one area of ​​the track system 108, and controlling the second or another group of container transport vehicles 201 according to another MAPF in another area of ​​the track system 108. Different MAPF algorithms can be executed in parallel by different computer systems to speed up the execution.

[0114] For example, a container transport vehicle 201 performing a specific task is an excavator that prepares a particular storage container 106 for further transport by other container transport vehicles 201 by first removing other storage containers 106 stacked on top of a particular storage container 106 in storage column 105. Container transport vehicles 201 performing specific tasks may have different movement patterns and speeds compared to other container transport vehicles 201. Therefore, these can be controlled individually or adjusted in routing decisions to take these differences into account.

[0115] After performing the first step 410 of the method (i.e., running the MAPF algorithm), routes for container delivery vehicles 201 are established and assigned. These routes run from the current location of container delivery vehicles 201 to the destination location for the assignment task.

[0116] The next step 420 of the method is to determine how far the container transport vehicle 201 can travel on the first part of the assigned route within a set time interval. The duration of the set time interval can be set according to the size of the automated storage and retrieval system 1 and the number of container transport vehicles 201 to be included in the MAPF algorithm.

[0117] According to one embodiment, the time interval is defined as the time interval for the container transport vehicle 201 to move from its current position to a position above the nearest adjacent storage column 105 on the track system 108. If the container transport vehicle 201 has just passed a position above storage column 105, it will not be able to change direction until it reaches the next nearest adjacent storage column. The time interval will then be the time for the container transport vehicle 201 to move to the nearest storage column 105, where the container transport vehicle can change direction if necessary.

[0118] According to another embodiment, the set time interval corresponds to the execution time of the control system 500 for running the MAPF algorithm, that is, for establishing a route and instructing the container transport vehicle 201 to move along the established route. This provides optimal routing because when the container transport vehicle 201 reaches the end of the locked route, a possible new route may have already been established through the MAPF algorithm. Therefore, the container transport vehicle 201 does not need to stop at the end of the locked route to receive new driving instructions, but can continue and follow the first assigned route, or be rerouted to a new route without stopping.

[0119] The next step 430 of the method is to lock the first part of the assigned route that the container transport vehicle 201 can travel on within a set time interval. This means that this part of the route cannot be changed, while the remaining assigned routes established by MAPF can be changed to new routes starting from the end position of the locked route.

[0120] The next step 440 instructs the container transport vehicles 201 to move from their current location to the destination location along the assigned locked route.

[0121] Repeat steps 410 to 440 for each container transport vehicle 201 until they have completed their assigned tasks. Each repetition of this method can be viewed as an iteration, where each iteration allows the container transport vehicle 210 to reroute from the routes established by MAPF in previous iterations.

[0122] According to this method, the container transport vehicle 201 can easily change the type of task or objective before completing the first assigned task, or new active container transport vehicles 201 can be added for operation on the storage system.

[0123] According to one embodiment of the invention, if the container delivery vehicle 201 is given priority, the locked route is extended. An example of this is when the port signals that it is ready to receive the storage container 106 from the container delivery vehicle 201. In this case, the complete route determined by the MAPF for the container delivery vehicle 201 from its current location to the port is locked and cannot be changed until the assigned task (e.g., delivering the storage container to the port) is completed.

[0124] According to another embodiment of the invention, if the container transport vehicle 201 does not respond to an instruction from the control system 500, the locked route is also extended. This may be due to a faulty container transport vehicle 201. It may have stopped somewhere on its locked route or failed to respond to instructions, such as a rerouting instruction at the end of the locked route. If so, it can continue along its assigned route to a place, i.e., the unlocked portion of the assigned route. By locking the entire route established by the MAPF, other container transport vehicles will avoid colliding with it.

[0125] By extending the locked route to include the complete route established by the MAPF algorithm—that is, the task from the current location of container transport vehicle 201 to its destination location—potential conflicts with other container transport vehicles 201 are avoided. This is advantageous, for example, when container transport vehicle 201 is given priority, or when a port signals that it is ready to interact with an assigned container transport vehicle 201.

[0126] According to one embodiment of the method, locked routes are excluded from execution in the MAPF algorithm. For container transport vehicles 201 operating normally without priority, this means that their current location is used as input to the MAPF algorithm; that is, the current location provides a set of destination locations for the locked routes. For container transport vehicles 201 with priority, or container transport vehicles 201 that are malfunctioning, the fully established route to the destination location is excluded from further execution in the MAPF algorithm.

[0127] Several factors can be used to determine which container delivery vehicles are given priority. Some tasks have a greater impact on performance than others. Container delivery vehicles 201 assigned to deliver storage container 106 within a port are typically prioritized over those assigned to deliver storage container 106 to storage column 105. Generally, an optimal route is first created for the prioritized container delivery vehicles 201. Different routing algorithms exist to determine route priority and optimal routes. These are based on a cost function and a different set of input parameters, such as time and distance to the destination, task priority, expected waiting time at the port, etc.

[0128] As described above, the MAPF algorithm is used to establish and assign routes for container transport vehicles 201 on the orbital system 108 from their current positions to their destination positions. The inputs to the MAPF algorithm are the layout of the orbital system 108, the operation of the container transport vehicles 201, and the current and destination positions of each container transport vehicle 201.

[0129] According to one embodiment of the method, an additional input to the MAPF algorithm is, for example, the required gap between each route established by the MAPF algorithm to provide sufficient clearance to avoid collisions with the margin. The required gap is suitable for the type of container transport vehicle 201 used for the mission and the type of track used on the route of the mission to reach the destination location.

[0130] A dual-track configuration allows two container transport vehicles to pass each other on tracks on two adjacent storage columns 105. A single-track configuration does not allow container transport vehicles 201 to pass, and if it is not possible to remove an obstructing container transport vehicle, a passage gap corresponding to the footprint of at least one storage column between two passing container transport vehicles 201 may be required.

[0131] According to one embodiment of the method, the movement of the container delivery vehicle 201 is further controlled to avoid potential queuing problems at the destination location. This can be achieved in different ways. For example, if it is anticipated that several container delivery vehicles 201 will arrive at the same port approximately simultaneously, they can be sorted, and the speed of the lowest-ranked container delivery vehicle 201 can be reduced, or they can be parked in a non-obstructive location until the highest-ranked container delivery vehicle 201 has completed its task at the port. Another way to avoid foreseeable queuing problems, for example, is to redirect the container delivery vehicles to complete their assigned tasks at other destination locations, such as delivering storage container 106 at another port.

[0132] Different container transport vehicles exist with different specifications (such as acceleration, speed, and maximum load). Additional inputs to the MAPF algorithm can be based on the weight of the transported storage container 106 and the condition of the container transport vehicle 201 (e.g., low battery, worn parts, wheel grip, etc.) to provide details of the type of container transport vehicle 201 assigned to perform the task and the current load on the container transport vehicle 201. This additional input can influence how the movement of the container transport vehicle 201 is controlled and whether the clearance between vehicles needs to be increased.

[0133] Figure 4 This shows a simple example of how to build routes based on the old routing method and how to build routes based on the improved routing method described above.

[0134] R1 and R2 indicate the current locations of container transport vehicles 1 and 2. D1 and D2 indicate the destination locations of container transport vehicles 1 and 2.

[0135] In this example, robot 1 at R1 receives its task just before robot 2 at R2. Based on the previous routing system, a route from robot 1's current position R1 to its destination D1 will first be planned and locked. Next, a route will be planned for robot 2, ensuring it doesn't conflict with robot 1's already established and locked route. Figure 4 As shown, the route taken by robot 2 is not optimal in terms of travel distance because it needs to avoid grid space D1 and may need to avoid any other locked grid spaces on the route assigned from R1 to D1.

[0136] According to the improved routing method disclosed in this paper, only the first part of the route established for container delivery vehicles is locked, while the last part of the established route is a planned route that can be changed. This means that when container delivery vehicles reach the end of the locked route and run the MAPF algorithm again, they can reroute to follow a new route from the current starting position of the locked route end.

[0137] Therefore, when establishing the route of robot 2 using the MAPF algorithm, assuming that robot 1 has not yet reached the end of the first locked section, the last part of robot 1's route will not be locked, thus generating the optimal route for the two container transport vehicles.

[0138] This new routing method is both flexible and efficient, taking into account all routes taken by all container delivery vehicles 201 at multiple stages to their assigned destination locations as a given container delivery vehicle travels along its assigned route.

[0139] The invention is further defined by a control system 500, which controls the effective route and rerouting of the container transport vehicle 201 that transports the storage container 106 in the automated storage and retrieval system 1, as described above with reference to FIG1.

[0140] The above reference Figure 2 A control system 500 is described. It further includes a processor configured to run a computer program, which, when executed, performs the aforementioned reference. Figure 3 This method enables efficient routing and rerouting of the container transport vehicle 201 that transports the storage container 106 in the automated storage and retrieval system 1. A computer program can run in the processor of the routing planner 200.

Claims

1. A method for routing and rerouting a container transport vehicle (201) carrying a storage container (106) in an automated storage and retrieval system comprising a frame structure (100), the frame structure (100) forming a three-dimensional storage grid structure (104) for storing the storage container (106) in a storage column (105), the frame structure comprising a grid-based track system (108) arranged above the storage column (105) having a track system (108), the track system (108) providing usable routes for the container transport vehicle (201) to transport and transfer the storage container (106) to and from the storage column (105), and wherein, Each container transport vehicle (201) includes a first set of wheels and a second set of wheels, the first set of wheels being configured to move the vehicle along a first direction (X) of the grid-based track system, and the second set of wheels being configured to move the vehicle along a second direction (Y) of the grid-based track system (108), the second direction (Y) being perpendicular to the first direction (X). The movement of the container transport vehicle is controlled by a control system (500), which determines the task to be performed by the designated container transport vehicle (201), determines the destination location for performing the task, and determines the route that the container transport vehicle (201) will travel on the track system (108). The method is characterized by comprising the following steps performed by the control system (500): a. Run (410) the Multi-Agent Pathfinding (MAPF) algorithm in the control system (500) to establish and assign routes for the container transport vehicle (201) on the track system (108) from the current location of the container transport vehicle (201) to the destination location for the assigned task, and b. Determine how far the container transport vehicle (201) described in (420) is able to travel as the first part on an assigned route within a set time interval, the first part being shorter than the assigned route to the destination. c. Locking (430) the first portion of the assigned route that the container transport vehicle (201) is capable of traveling within the set time interval, wherein the locked first portion of the route cannot be changed and is excluded from consideration of available routes during the execution of the MAPF algorithm. d. The first part of the lock for extending the assigned route for the priority container transport vehicle (201), e. Instruct (440) the container transport vehicle (201) to move from its current position to the destination position on the locked first portion of the assigned route. f. Repeat steps a through d.

2. The method according to claim 1, wherein, The set time interval mentioned in step b corresponds to the execution time of the control system (500) for executing the MAPF algorithm and instructing the container transport vehicle (201) to move according to the established route.

3. The method according to claim 1 or 2, wherein, The upper limit of the set time interval in step b is the time elapsed for all container transport vehicles (201) to move from their current positions to their positions on the track system (108) above the nearest storage column (105) where the container transport vehicles (201) can change direction.

4. The method according to claim 1, wherein, The duration of the set time interval in step b is set according to the size of the automatic storage and / or retrieval system and the number of container transport vehicles (201) to be included in the MAPF algorithm.

5. The method according to claim 1, wherein, The method includes a portion of locking the assigned route for container transport vehicles (201) that do not respond to instructions.

6. The method according to claim 5, wherein, The locked portion of the assigned route extends from the current position of the container transport vehicle (201) to the destination position along the route established by the MAPF algorithm.

7. The method according to claim 1, wherein, The gaps between each route established by the MAPF algorithm are suitable for the type of container transport vehicle (201) traveling on the assigned routes.

8. The method according to claim 1, wherein, The movement of the container transport vehicle (201) is controlled to avoid queuing problems at the destination location.

9. The method according to claim 8, wherein, If the queuing problem is anticipated at the destination location, the container transport vehicle (201) is redirected.

10. The method according to claim 9, wherein, The container transport vehicle (201) is redirected to a location or route where the container transport vehicle (201) does not exist or is not heading.

11. The method according to claim 1, wherein, The movement of the container transport vehicle (201) is controlled according to the type of the container transport vehicle (201), the current load it carries, and the condition of the container transport vehicle (201).

12. A control system (500) for controlling the efficient routing and rerouting of a container transport vehicle (201) carrying a storage container (106) in an automated storage and retrieval system comprising a frame structure (100), the frame structure (100) forming a three-dimensional storage grid structure (104) for storing the storage container (106) in a storage column (105), the frame structure (100) comprising a grid-based track system (108) arranged above the storage column (105) having a track system (108), the track system (108) providing usable routes for the container transport vehicle (201) to transport and transfer the storage container (106) to and from the storage column (105), and wherein, Each container transport vehicle (201) includes a first set of wheels and a second set of wheels. The first set of wheels is configured to move the vehicle along a first direction (X) of the grid-based track system, and the second set of wheels is configured to move the vehicle along a second direction (Y) of the grid-based track system (108), the second direction (Y) being perpendicular to the first direction (X). The movement of the container transport vehicles is controlled by a control system (500), which determines the task to be performed by the designated container transport vehicle (201), determines the destination location for performing the task, and determines the route that the container transport vehicle (201) will travel on the track system (108). The control system (500) includes: a route planner (200) for finding the optimal route for the container transport vehicle (201); a database (210) for keeping track of the storage container (106); and a main controller (220) connected to a transmitter / receiver (225), wherein the control system (500) is adapted to perform the method according to any one of claims 1 to 11 and transmit control commands to each container transport vehicle (201).

13. A computer-readable storage medium comprising a computer program product storing instructions that, when executed by a processor in a control system (500) of an automated storage and retrieval system (1), perform the method according to any one of claims 1 to 11 for effectively routing and rerouting a container transport vehicle (201) carrying a storage container (106) in the automated storage and retrieval system.

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