Conveyance system and conveyance method

Abstract

[Problem] To make it possible to execute article conveyance efficiently. [Solution] This conveyance system comprises: a plurality of conveyance vehicles that travel on a track and convey articles; and a controller that manages conveyance commands in which conveyance sources and conveyance destinations of the articles are designated, and assigns the conveyance commands to the conveyance vehicles. When assigning a first conveyance command having a predetermined placement part as the conveyance destination, the controller confirms whether or not a second conveyance command having the predetermined placement part as a conveyance source exists, and if the second conveyance command exists, assigns the second conveyance command preferentially over the first conveyance command.

Description

Transport System and Transport Method

[0001] The present invention relates to a transport system and a transport method.

[0002] Conventionally, a transport system is known that includes a transport vehicle that travels on a track to transport an article, and a controller that assigns a transport command specifying the transport source and destination of the article to the transport vehicle. In Patent Document 1, when the transport vehicle transporting the article arrives at the transport destination and cannot unload the article because there are other articles at the transport destination, the article is unloaded onto a temporary storage shelf near the transport destination, and other articles present at the transport destination are picked up and transported. A technique for controlling such is disclosed.

[0003] Japanese Patent No. 4337683

[0004] In a transport system, the more times the article is picked up and unloaded, the more time is required, and the transport efficiency of the article becomes low.

[0005] The present invention provides a transport system and a transport method capable of efficiently performing the transport of an article.

[0006] In an aspect of the present invention, a transport system includes a plurality of transport vehicles that travel on a track to transport an article, and a controller that manages a transport command specifying the transport source and destination of the article and assigns the transport command to each transport vehicle. When the controller assigns a first transport command having a predetermined placement part as the transport destination, the controller checks whether there is a second transport command having the predetermined placement part as the transport source. When the second transport command exists, a transport system is provided that assigns the second transport command with priority over the first transport command.

[0007] In an embodiment of the present invention, a transport method is provided for a transport system comprising: a plurality of transport vehicles that travel along a track to transport articles; and a controller that manages transport commands specifying the source and destination of articles and assigns transport commands to each transport vehicle, the method comprising: checking whether a second transport command exists that specifies a predetermined loading unit as the source when assigning a first transport command that specifies a predetermined loading unit as the destination; and, if a second transport command exists, assigning the second transport command with priority over the first transport command.

[0008] According to the transport system and transport method of the present invention, when assigning a first transport command to a predetermined loading unit as the transport destination, if there is a second transport command that uses the predetermined loading unit as the transport source, the second transport command is assigned with priority over the first transport command. This prevents situations where the execution of the first transport command cannot be completed due to the execution of the second transport command not being completed, thus enabling efficient transport of goods.

[0009] Furthermore, in the above embodiment of the transport system, if the controller is in a situation where the candidate to which the first transport command is assigned is the first transport vehicle, and a second transport command exists, the controller may assign the second transport command to the first transport vehicle, and if a second transport command does not exist, the controller may assign the first transport command to the first transport vehicle. According to this embodiment, if a second transport command exists, the second transport command is assigned to the first transport vehicle, and if a second transport command does not exist, the first transport command is assigned to the first transport vehicle, so that the transport of goods can be carried out efficiently. Also, in the above embodiment of the transport system, if the controller has assigned the second transport command to the first transport vehicle, the controller may assign the first transport command to a second transport vehicle different from the first transport vehicle. According to this embodiment, the execution of the first transport command can be completed quickly.

[0010] Furthermore, in the above embodiment of the transport system, the controller may select a transport vehicle that is closer to the source specified in the transport command, among the transport vehicles to which no transport command has been assigned, as a candidate for assignment of the transport command. According to this embodiment, the travel distance of the transport vehicle executing the transport command can be shortened, thus enabling efficient transport of goods. Also, in the above embodiment of the transport system, the controller may check whether a second transport command exists if the number of transport vehicles capable of executing a transport command is less than the number of transport commands being managed. According to this embodiment, the transport command that should be executed with priority is assigned to the transport vehicle capable of executing the transport command, so that goods can be transported efficiently without wasting operational transport vehicles.

[0011] Furthermore, in the above embodiment of the transport system, if the transport vehicle is not in a state where an item can be placed on the designated loading area, the controller may assign a first transport command to the transport vehicle, which includes a command to stop near the designated loading area and a command to place the item on the designated loading area. If the item becomes ready to be placed on the designated loading area within a certain time after the transport vehicle has stopped near the designated loading area, the controller may notify the transport vehicle to execute the command to place the item on the designated loading area. If the item does not become ready to be placed on the designated loading area within a certain time after the transport vehicle has stopped near the designated loading area, the controller may assign a third transport command to the transport vehicle, which uses the position where the transport vehicle stopped as the source of transport and a position different from the designated loading area as the destination. According to this embodiment, it is possible to suppress the situation in which an item cannot be placed on the designated loading area for a long period of time.

[0012] Furthermore, in the above embodiment of the transport system, if an item is not in a state where it can be placed on the designated loading area, including the case where the execution of the assigned second transport command has not been completed, the controller may notify the transport vehicle to execute a command to place the item on the designated loading area if the execution of the second transport command is completed within a certain time after the transport vehicle has stopped near the designated loading area, and assign a third transport command to the transport vehicle if the execution of the second transport command is not completed within a certain time after the transport vehicle has stopped near the designated loading area. According to this embodiment, it is possible to suppress the situation in which an item cannot be placed on the designated loading area for a long period of time.

[0013] Furthermore, in the above embodiment of the transport system, if the controller has not completed the execution of the second transport command within a certain time after the transport vehicle has stopped near the predetermined loading area, it may release the assignment of the first transport command and then assign the third transport command to the transport vehicle. This embodiment makes it possible to prevent a prolonged period in which an item cannot be placed on the predetermined loading area. Furthermore, in the above embodiment of the transport system, the track may be a grid-like track having a plurality of first tracks extending along a first direction and a plurality of second tracks extending along a second direction different from the first direction, with the plurality of first tracks and the plurality of second tracks forming a plurality of squares. This embodiment makes it possible to achieve efficient transport of items by the transport vehicle.

[0014] This is a perspective view showing an example of a transport system according to the first embodiment. This is a perspective view showing an example of a transport vehicle used in the transport system according to the first embodiment. This is a block diagram showing an example of the functional configuration of a transport vehicle and a controller according to the first embodiment. This is a diagram illustrating an example of the allocation of transport commands according to the first embodiment. This is a flowchart illustrating an example of the allocation process for transport commands according to the first embodiment. This is a block diagram showing an example of the functional configuration of a transport vehicle and a controller according to the second embodiment. This is a diagram illustrating an example of the allocation of transport commands according to the second embodiment. This is a diagram illustrating an example of the allocation of transport commands according to the second embodiment. This is a flowchart illustrating an example of the allocation process for transport commands according to the second embodiment. This is a flowchart illustrating an example of the allocation process for transport commands according to the second embodiment.

[0015] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to what is described below. The following embodiments do not limit the invention as claimed. In the drawings, the scale may be appropriately changed, such as by enlarging, reducing, or emphasizing parts of the drawings, in order to illustrate the embodiments. Also, in the drawings, directions in the figures may be explained using the XYZ Cartesian coordinate system. In the XYZ Cartesian coordinate system, the vertical direction is the Z direction, and the horizontal directions are the X and Y directions. In the X, Y, and Z directions, the direction pointed to by the arrow is the + direction, and the direction opposite to the direction pointed to by the arrow is the - direction.

[0016] [First Embodiment] Figure 1 is a perspective view showing an example of a transport system according to the first embodiment. Figure 2 is a perspective view showing an example of a transport vehicle used in the transport system according to the first embodiment. The transport system 1 includes, for example, a plurality of transport vehicles 100 that transport articles M by traveling along a track (grid-shaped track R) in a clean room of a semiconductor manufacturing plant, and a controller 200 that assigns transport commands to each transport vehicle 100, specifying the source and destination of the articles M. The transport system 1 may also include a higher-level controller (e.g., MCS: Material Control System) above the controller 200. The higher-level controller is responsible for generating, modifying, and deleting transport commands (e.g., deletion due to cancellation of transport command execution) and for overall control of the transport system 1 to the controller 200 that assigns transport commands.

[0017] The transport system 1 comprises a plurality of transport vehicles 100 that travel along a grid-like track R, and a controller 200 that controls each of the plurality of transport vehicles 100. The controller 200 controls the movement of each of the plurality of transport vehicles 100. Details of the controller 200 will be described later. Also, in Figure 1, only one transport vehicle 100 is shown, and the other transport vehicles 100 are omitted. In this embodiment, the case in which the transport vehicle 100 is an overhead transport vehicle will be used as an example. The transport vehicle 100 travels along the grid-like track R and transports items M such as a FOUP (Front Opening Unified Pod) that contains semiconductor wafers or a reticle Pod that contains reticles.

[0018] The grid-like track R is installed, for example, suspended from the ceiling or near the ceiling of a building such as a cleanroom by a suspension member H. The grid-like track R is provided above a processing device (not shown) for transferring goods M, a stocker (automatically moving, not shown), a buffer (not shown), etc. Note that Figure 1 shows a part of the grid-like track R. The grid-like track R is formed by continuously creating similar configurations in the first direction DR1 (X direction) and the second direction DR2 (Y direction) from the illustrated configuration.

[0019] The grid-like track R has a plurality of first track R1 extending along a first direction DR1 and a plurality of second track R2 extending along a second direction DR2 different from the first direction DR1, and the plurality of first track R1 and plurality of second track R2 form a plurality of grids. The grid-like track R has first track R1, second track R2, and intersecting track R3. The first track R1 extends along the X direction (first direction DR1). The second track R2 extends along the Y direction (second direction DR2). The plurality of first track R1 and plurality of second track R2 are provided orthogonally to each other and are arranged so as not to contact each other. The intersecting track R3 is located at the intersection of the first track R1 and the second track R2. The intersecting track R3 is adjacent to the first track R1 in the first direction DR1 and adjacent to the second track R2 in the second direction DR2. The intersecting track R3, together with the first track R1, forms a track in the first direction DR1, and together with the second track R2, forms a track in the second direction DR2.

[0020] The grid-like orbitals R are arranged such that, in a plan view, multiple cells C are adjacent to each other and arranged vertically and horizontally (first direction DR1, second direction DR2) by having the first orbital R1 and the second orbital R2 oriented in mutually orthogonal directions. Cells C are sometimes called "grid cells" or "mesh cells". In a plan view, one cell C is the portion enclosed by two adjacent first orbitals R1 in the second direction DR2 and two adjacent second orbitals R2 in the first direction DR1.

[0021] The first track R1 has a running surface R1a. The second track R2 has a running surface R2a. The crossing track R3 has a running surface R3a. The wheels 21 of the transport vehicle 100 roll on the running surfaces R1a, R2a, and R3a. A gap D is formed between the first track R1 and the crossing track R3. Similarly, a gap D is formed between the second track R2 and the crossing track R3. The gap D is the portion through which the connecting section 30, which is part of the transport vehicle 100, passes when the transport vehicle 100 travels on the first track R1 and crosses the second track R2, or when it travels on the second track R2 and crosses the first track R1. Therefore, the gap D is formed to be wide enough for the connecting section 30 to pass through.

[0022] The transport vehicle 100 has a main body 10, a running section 20, and a connecting section 30. The main body 10 is positioned below (on the -Z side) the grid-shaped track R. The main body 10 is sized to fit within one cell C of the grid-shaped track R in a plan view. Therefore, when the transport vehicles 100 pass each other on adjacent first track R1 or second track R2, the main body 10s do not interfere with each other.

[0023] The main body 10 comprises an upper unit 17 and a transfer device 18. The upper unit 17 is suspended from the travel unit 20 via a connecting unit 30. The travel unit 20 is provided at each of the four corners of the upper surface 17a of the upper unit 17. The transfer device 18 is located below the upper unit 17 and transfers articles M to predetermined positions. The transfer device 18 includes an article holding unit 13 for holding articles M, a lifting drive unit 14 for raising and lowering the article holding unit 13 vertically, a side-extension mechanism 11 for sliding the lifting drive unit 14 horizontally, and a rotating unit 12 for rotating the side-extension mechanism 11. The transport vehicle 100 operates the lifting drive unit 14 and the side-extension mechanism 11 to unload articles M onto a loading unit located below the cell C, or to grab articles M from the loading unit.

[0024] The running section 20 has running wheels 21 and auxiliary wheels 22. One auxiliary wheel 22 is positioned in front of and behind the running wheels 21 in the direction of travel. The running wheels 21 are attached to axles provided on support members 31 of the connecting section 30. Each of the running wheels 21 is rotationally driven by the driving force of the running drive section 33. The connecting member 32 of the connecting section 30 is provided so as to be rotatable in the θZ direction about the pivot axis AX2 and contains a transmission mechanism that transmits the driving force of the running drive section 33 to the running wheels 21. By rotating the connecting member 32 about the pivot axis AX2, the running wheels 21 can be rotated in the θZ direction about the pivot axis AX2.

[0025] The connecting section 30 is equipped with a direction changing mechanism 34. The direction changing mechanism 34 rotates a pinion gear 36 using a drive source 35, moving the drive source 35 along the rack 37, thereby rotating the travel wheels 21 in the θZ direction around the pivot axis AX2. By rotating the travel wheels 21, the travel direction of the transport vehicle 100 can be switched from a state where the travel direction is the first direction DR1 to a state where the travel direction is the second direction DR2, or from a state where the travel direction is the second direction DR2 to a state where the travel direction is the first direction DR1.

[0026] The transport vehicle 100 is equipped with a position detection unit (not shown) that detects its own position information. The position detection unit detects its current position by, for example, non-contact detecting position markers (not shown) provided for each cell C of the grid-like track R. The transport vehicle 100 can selectively move along the grid-like track R in either the first direction DR1 or the second direction DR2.

[0027] Each cell C of the grid-like track R is set up as a blocking section where, if any one of the multiple transport vehicles 100 occupies the cell C, exclusive control is implemented to prevent other transport vehicles 100 from entering. In other words, cell C is also an area that functions as a blocking section. A transport vehicle 100 located in a predetermined cell C can proceed to an adjacent cell C if it obtains permission from the controller 200 to occupy that cell C, but if it does not obtain permission from the controller 200, it will not proceed to that cell C and will stop in the predetermined cell C. In this embodiment, interference between transport vehicles 100 is prevented by granting such permission to occupy cell C.

[0028] In the configuration described above, when the controller 200 assigns a first transport command to a predetermined loading unit as the transport destination, it checks whether a second transport command exists that also uses the predetermined loading unit as the transport source. If a second transport command exists, the controller 200 assigns the second transport command with priority over the first transport command. In other words, in the transport system 1, in situations where the execution of the first transport command cannot be completed until the execution of the second transport command is completed, the second transport command is assigned to the transport vehicle with priority over the first transport command. As a result, the transport system 1 can reduce the number of times the item M is grabbed and unloaded compared to a technology that unloads the item M onto a temporary storage shelf near the destination if other items are present at the destination, and then grabs and transports the other items present at the destination. This reduces the number of times the transport vehicle 100 transports the item M, enabling efficient transport of the item M.

[0029] Figure 3 is a block diagram showing an example of the functional configuration of a transport vehicle and a controller according to the first embodiment. Each transport vehicle 100 and the controller 200 are connected to communicate via an arbitrary communication system. As shown in Figure 3, the transport vehicle 100 has a travel control unit 110, a communication control unit 120, and a storage unit 130.

[0030] The communication control unit 120 controls the transmission and reception of various types of information exchanged with the controller 200. The communication control unit 120 stores the transport commands received from the controller 200 in the storage unit 130.

[0031] The travel control unit 110 controls each part of the transport vehicle 100 based on the transport command stored in the storage unit 130. For example, the travel control unit 110 controls the travel of the transport vehicle 100 based on the transport source and destination specified by the transport command, causing it to travel along the grid-shaped track R. The travel control unit 110 causes various sensors mounted on the transport vehicle 100 to perform detection and stores the detection results in the storage unit 130. The various sensors include, for example, a position sensor, a load sensor, and a forward sensor. The position sensor detects the current position by detecting a position marker provided for each cell C of the grid-shaped track R. The load sensor detects the presence or absence of an item M in the transport vehicle 100. The forward sensor monitors the direction of travel (travel direction) of the transport vehicle 100 and detects the presence of other transport vehicles 100 ahead. Each transport vehicle 100 controls its travel speed based on the detection of the presence of other transport vehicles 100 ahead by the forward sensor to prevent collision with other transport vehicles 100. The transport vehicle 100 does not necessarily have to be equipped with at least one of the position sensor, load sensor, and forward sensor, and may be equipped with other sensors as well.

[0032] The driving control unit 110 generates state information for the transport vehicle 100 using the information stored in the storage unit 130. For example, the state information includes identification information that identifies the transport vehicle 100, as well as information regarding the current position, destination, driving status, cargo status, forward status, and whether or not a transport command has been issued. The current position is information indicating the current position of the transport vehicle 100 as detected by the position sensor. The destination is information indicating the destination of the transport vehicle 100, which is specified in the transport command stored in the storage unit 130. The destination may be the destination when the transport vehicle 100 is transporting an item M.

[0033] The driving status is information indicating the current speed of the transport vehicle 100. For example, the driving status may indicate that the transport vehicle 100 is in motion when the speed is greater than 0 (e.g., flag "1"), and that the transport vehicle 100 is stopped when the speed is 0 (e.g., flag "0"). The cargo status is information indicating the presence or absence of an item M detected by the cargo sensor (e.g., present "1", absent "0") and identification information to identify the cargo being transported. The forward status is information indicating whether or not another transport vehicle 100 exists within the detection range of the forward sensor (e.g., present "1", absent "0"). The presence or absence of a transport command is information indicating the presence or absence of a transport command being executed.

[0034] The memory unit 130 is, for example, a non-volatile memory, and stores various information such as map information including the grid-like track R and status information. The travel control unit 110 may set a travel route based on the transport command received from the controller 200 and the map information of the grid-like track R stored in the memory unit 130. The travel control unit 110 generates status information as appropriate and updates the status information stored in the memory unit 130 to the latest status information. The communication control unit 120 transmits the status information stored in the memory unit 130 to the controller 200 in response to a request from the controller 200 to transmit status information.

[0035] The controller 200 includes an allocation unit 210, a communication control unit 220, and a storage unit 230. The controller 200 is a computer device that performs processing of various types of information, and includes, for example, a CPU (Central Processing Unit), main memory, storage device, communication device, etc. The configuration of the computer device is arbitrary; for example, it may be composed of one device or multiple devices. The communication control unit 220 controls communication with each transport vehicle 100 by arbitrary communication, requests status information from each transport vehicle 100, and controls the reception of status information from each transport vehicle 100. The storage unit 230 is, for example, a non-volatile memory, and stores the status information received by the communication control unit 220. The storage unit 230 stores, for example, the status information of each transport vehicle 100, associating it with the identification information of each transport vehicle 100.

[0036] The allocation unit 210 determines which transport vehicle 100 will be responsible for the transport command according to the task, based on information about the source and destination of the transport of the item M, which is determined by a pre-assigned task (e.g., transport of item M), and status information stored in the storage unit 230. In this embodiment, the determination of which transport vehicle 100 will be responsible for the transport command is called the allocation of the transport command. Furthermore, from the viewpoint of the transport efficiency of the item M, it is preferable to allocate the transport command to the transport vehicle 100 that is closer to the item M to be transported, among the transport vehicles 100 to which the transport command can be allocated.

[0037] When the allocation unit 210 allocates a first transport command to a predetermined loading unit as the transport destination, it checks whether a second transport command exists that uses the predetermined loading unit as the transport source, and if a second transport command exists, it allocates the second transport command with priority over the first transport command. Figure 4 is a diagram illustrating an example of the allocation of transport commands according to the first embodiment. Hereinafter, when transport vehicles 100 are distinguished individually, they will be referred to as transport vehicle 100A, transport vehicle 100B, etc. Also, when cells C are distinguished individually, they will be referred to as cell C1, cell C2, etc. Also, when articles M are distinguished individually, they will be referred to as article M1, article M2, etc.

[0038] As shown in Figure 4, consider the case where, in a grid-like track R, there is a first transport command that uses cell C1, which corresponds to the position (placement) where article M1 is placed, as the transport source, and a second transport command that uses cell C2, which corresponds to the position (placement) where article M2 is placed, as the transport source. Here, in the first transport command, the transport source is cell C1 and the transport destination is cell C2. Cell C2 corresponds to a "predetermined placement area".

[0039] The allocation unit 210 selects the transport vehicle 100 that is closest to the transport source specified in the transport command, from among the transport vehicles 100 to which no transport command has been assigned, as a candidate for assignment of the transport command. Here, among the transport vehicles 100 to which the transport command can be assigned for the first transport command, the transport vehicle 100 closest to the item M1 is transport vehicle 100A. The block arrows in the figure show an example of the travel route of transport vehicle 100A. Note that transport vehicle 100A does not necessarily travel along the illustrated travel route.

[0040] In this situation, the allocation unit 210 selects the transport vehicle 100A that is closer to cell C1 corresponding to the location where item M1 is placed as a candidate for allocation of the first transport command, which has cell C1 as the transport source and cell C2 as the transport destination. Transport vehicle 100A corresponds to the "first transport vehicle". Then, when the candidate for allocation of the first transport command is transport vehicle 100A, the allocation unit 210 uses the storage unit 230 to check whether a second transport command has existed with cell C2 as the transport source. At this time, if a second transport command exists, the allocation unit 210 allocates the second transport command to transport vehicle 100A. In other words, if the execution of the first transport command to transport item M1 to cell C2 cannot be completed until the execution of the second transport command is completed, the allocation unit 210 allocates the second transport command to transport vehicle 100A with priority over the first transport command. The communication control unit 220 transmits the second transport command, which has been assigned by the assignment unit 210, to the transport vehicle 100A. As a result, the transport vehicle 100A travels toward cell C2 in order to execute the second transport command.

[0041] Meanwhile, the allocation unit 210 assigns the first transport command to the transport vehicle 100A if there is no second transport command. The communication control unit 220 transmits the first transport command assigned by the allocation unit 210 to the transport vehicle 100A. As a result, the transport vehicle 100A travels toward cell C1 to execute the first transport command.

[0042] Furthermore, when the allocation unit 210 assigns the second transport command to transport vehicle 100A, it assigns the first transport command to a different transport vehicle 100B. Transport vehicle 100B corresponds to the "second transport vehicle". The communication control unit 220 transmits the first transport command assigned by the allocation unit 210 to transport vehicle 100B. As a result, transport vehicle 100B travels toward cell C1 to execute the first transport command. In other words, after the allocation unit 210 assigns the second transport command to transport vehicle 100A, it assigns the first transport command to transport vehicle 100B because the execution of the second transport command can be completed before the execution of the first transport command can be completed.

[0043] Further, when the number of transport vehicles 100 capable of executing transport commands is less than the number of transport commands being managed, the allocation unit 210 may check whether there is a second transport command. Specifically, the allocation unit 210 compares the number of transport commands stored in the storage unit 230 with the number of transport vehicles 100 capable of executing transport commands based on the status information (e.g., presence or absence of a transport command) of each transport vehicle 100 stored in the storage unit 230. Then, when allocating a first transport command with a predetermined placement unit as the destination, the allocation unit 210 checks whether there is a second transport command with the predetermined placement unit as the source, only when the number of transport vehicles 100 capable of executing transport commands is less than the number of transport commands. In other words, the allocation unit 210 executes a process of checking whether there is a second transport command when a situation may occur in which the number of transport vehicles 100 for allocating transport commands is insufficient in the grid-shaped track R. That is, since the allocation unit 210 cannot complete the execution of the first transport command unless the execution of the second transport command is completed, when the number of transport vehicles 100 capable of executing transport commands is less than the number of transport commands, the allocation unit 210 allocates a second transport command to the available transport vehicles 100 as much as possible.

[0044] FIG. 5 is a flowchart showing an example of the transport command allocation process according to the first embodiment. As shown in FIG. 5, when allocating a first transport command with a predetermined placement unit as the destination, the allocation unit 210 checks whether there is a second transport command with the predetermined placement unit as the source (step S101). Specifically, the allocation unit 210 selects a transport vehicle 100A closer to the cell C1 corresponding to the position where the article M1 is placed as a candidate for allocation of a first transport command with cell C1 as the source and cell C2 as the destination. Then, the allocation unit 210 uses the storage unit 230 to check whether there is a second transport command with cell C2 as the source. The process of step S101 may be executed when the number of transport vehicles 100 capable of executing transport commands is less than the number of transport commands stored in the storage unit 230.

[0045] At this time, when there is a second transfer command (step S101: YES), the allocation unit 210 allocates the second transfer command to the transfer vehicle 100A with higher priority than the first transfer command (step S102). Specifically, when there is a second transfer command with cell C2 as the source, until the execution of the second transfer command is completed, the execution of the first transfer command for transporting the article M1 to cell C2 cannot be completed either. Therefore, the allocation unit 210 allocates the second transfer command to the transfer vehicle 100A with higher priority than the first transfer command.

[0046] On the other hand, when there is no second transfer command (step S101: NO), the allocation unit 210 allocates the first transfer command to the transfer vehicle 100A (step S103). Specifically, when there is no second transfer command with cell C2 as the source, there is no factor preventing the transport of the article M1 to cell C2. Therefore, the allocation unit 210 allocates the first transfer command to the transfer vehicle 100A.

[0047] As described above, when the transport system 1 allocates the first transfer command with a predetermined placement unit as the destination, if there is a second transfer command with the predetermined placement unit as the source, the transport system 1 allocates the second transfer command with higher priority than the first transfer command. Therefore, it is possible to suppress the situation where the execution of the first transfer command cannot be completed due to the incomplete execution of the second transfer command, and thus the transport of articles can be efficiently executed.

[0048] [Second Embodiment] In the second embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and detailed descriptions of the same components may be omitted.

[0049] FIG. 6 is a block diagram showing a functional configuration example of the transfer vehicle and the controller according to the second embodiment. As shown in FIG. 6, the transfer vehicle 100 includes a travel control unit 110, a communication control unit 120, and a storage unit 130. The controller 200a includes an allocation unit 210a, a communication control unit 220, and a storage unit 230.

[0050] If the item M is not in a state where it can be placed on the predetermined loading area, the allocation unit 210a assigns a first transport command to the transport vehicle 100, which includes a command to stop near the predetermined loading area and a command to place the item M on the predetermined loading area. If, within a certain time after the transport vehicle 100 has stopped near the predetermined loading area, the item M becomes in a state where it can be placed on the predetermined loading area, the allocation unit 210a notifies the transport vehicle 100 to execute the command to place the item M on the predetermined loading area. If, within a certain time after the transport vehicle 100 has stopped near the predetermined loading area, the item M does not become in a state where it can be placed on the predetermined loading area, the allocation unit 210a assigns a third transport command to the transport vehicle 100, which designates the position where the transport vehicle 100 stopped as the transport source and a position different from the predetermined loading area as the transport destination.

[0051] Figures 7 to 9 illustrate examples of the allocation of transport commands according to the second embodiment. Hereinafter, when transport vehicles 100 are individually distinguished, they will be referred to as transport vehicle 100A, transport vehicle 100B, etc. Similarly, when cells C are individually distinguished, they will be referred to as cell C1, cell C2, cell C3, etc. Furthermore, when items M are individually distinguished, they will be referred to as item M1, item M2, etc.

[0052] As shown in Figure 7, consider an example where, in a grid-like track R, there is a first transport command that uses cell C1 corresponding to the position where article M1 is placed as the transport source, and a second transport command that uses cell C2 corresponding to the position where article M2 is placed as the transport source. Here, the first transport command has cell C1 as the transport source and cell C2 as the transport destination. Cell C2 corresponds to a "predetermined placement area". The vicinity of the predetermined placement area is, for example, cell C located about one or two cells away from cell C2. In this embodiment, as an example, the vicinity of cell C2 (the predetermined placement area) is referred to as cell C3. Furthermore, the case where article M1 is not in a state where it can be placed in cell C2 includes the case where the execution of the assigned second transport command has not been completed.

[0053] The allocation unit 210a selects the transport vehicle 100 that is closest to the source specified in the transport command, from among the transport vehicles 100 to which no transport command has been assigned, as a candidate for assignment of the transport command. Here, for the first transport command, among the transport vehicles 100 to which the transport command can be assigned, the transport vehicle 100 that is closest to item M1 is transport vehicle 100A. Also, for the second transport command, among the transport vehicles 100 to which the transport command can be assigned, the transport vehicle 100 that is closer to item M2 is transport vehicle 100B.

[0054] In this situation, since the execution of the second transport command with cell C2 as the transport source has not been completed, the allocation unit 210a allocates a first transport command to the transport vehicle 100A, with cell C1 as the transport source, which includes a command to stop at cell C3, which is near cell C2, and a command to place the item M1 on cell C2. The allocation unit 210a also allocates a second transport command to the transport vehicle 100B.

[0055] As shown in Figure 8, upon execution of the first transport command, transport vehicle 100A arrives at cell C1 corresponding to the location where item M1 is placed and grasps item M1. Transport vehicle 100B, upon execution of the second transport command, travels toward cell C2 corresponding to the location where item M2 is placed.

[0056] As shown in Figure 9, the transport vehicle 100A stops at cell C3, which is near cell C2, upon execution of the first transport command. At this point, the execution of the second transport command is not yet complete. Now, suppose that while the transport vehicle 100B is traveling toward cell C2, which corresponds to the location where the item M2 is placed, some factor makes it difficult to execute the second transport command. Such factors include, for example, the execution of the second transport command assigned to the transport vehicle 100B being canceled, the transport vehicle 100B becoming unable to travel, the transport vehicle 100B's travel path becoming blocked or congested and unable to travel, or cell C2 becoming unavailable.

[0057] Furthermore, transport vehicles 100A and 100B transmit status information to the controller 200a as needed. The controller 200a controls each transport vehicle 100 based on the status information received from each transport vehicle 100. As a result, the controller 200a recognizes that transport vehicle 100A has arrived at cell C3. The allocation unit 210a then checks whether the cell C2 becomes ready to receive the item M1 within a certain time after transport vehicle 100A has stopped at cell C3. The state in which the item M1 can be received at cell C2 includes, for example, the completion of the execution of the second transport command. As described above, transport vehicle 100B is in a situation where it is difficult to execute the second transport command due to some factor.

[0058] If the assignment unit 210a determines that the item M1 cannot be placed in cell C2 within a certain time after the transport vehicle 100A has stopped in cell C3, it assigns a third transport command to the transport vehicle 100A, specifying the position where the transport vehicle 100A stopped (cell C3) as the transport source and a different position from cell C2 (any cell C to which the transport vehicle 100 can move) as the transport destination. The communication control unit 220 transmits the third transport command assigned by the assignment unit 210a to the transport vehicle 100A. The third transport command here is assigned to the transport vehicle 100A by canceling the first transport command or by overwriting the first transport command. As a result, the transport vehicle 100A erases the first transport command and executes the third transport command without transporting the item M1 to cell C2.

[0059] As described above, the transport system 1 includes a higher-level controller that is responsible for generating, modifying, and deleting transport commands. The process of canceling the first transport command or overwriting the first transport command with the third transport command is achieved by the controller 200a communicating with the higher-level controller to exchange information about the status of each transport vehicle 100 on the grid-like track R.

[0060] Furthermore, the allocation unit 210a requests the communication control unit 220 to notify the transport vehicle 100A to execute a command to place the item M1 in cell C2 if, within a certain time after the transport vehicle 100A has stopped in cell C3, the item M1 becomes ready to be placed in cell C2. In response to the request from the allocation unit 210a, the communication control unit 220 notifies the transport vehicle 100A to execute a command to place the item M1 in cell C2. As a result, the transport vehicle 100A transports the item M1 to cell C2 and completes the execution of the first transport command.

[0061] Figures 10 and 11 are flowcharts illustrating an example of the allocation process for transport commands according to the second embodiment. As shown in Figures 10 and 11, the allocation unit 210a checks whether the article M can be placed on a predetermined placement unit (step S201). Specifically, the allocation unit 210a checks whether the execution of the second transport command, with cell C2 as the transport source, has been completed.

[0062] Then, if it is not possible to place the article M in a predetermined placement area (step S201: NO), the allocation unit 210a assigns a first transport command that includes a command to stop near the predetermined placement area and a command to place the article M in the predetermined placement area (step S202). Specifically, if it is not possible to place the article M1 in the position of cell C2 because the execution of the second transport command has not been completed, the allocation unit 210a assigns a first transport command to the transport vehicle 100A that includes a command to stop at cell C3 near cell C2 and a command to place the article M1 in the position of cell C2.

[0063] On the other hand, if the item M can be placed on a predetermined placement area (step S201: YES), the allocation unit 210a assigns a first transport command to the predetermined placement area as the transport destination (step S203). Specifically, if the execution of the second transport command has been completed, or if there is no second transport command, the allocation unit 210a assigns a first transport command to the transport vehicle 100A to cell C2 as the transport destination.

[0064] Next, the allocation unit 210a checks whether the item M can be placed on the designated placement area within a certain time after the transport vehicle 100 has stopped near the designated placement area (step S204). Specifically, the allocation unit 210a checks whether the execution of the second transport command has been completed within a certain time after the transport vehicle 100A has stopped in cell C3, thereby confirming whether the item M1 can be placed in the position of cell C2.

[0065] At this time, if the allocation unit 210a becomes ready to place the item M on the predetermined placement area within a certain time after the transport vehicle 100 has stopped near the predetermined placement area (step S204: YES), it notifies the transport vehicle 100 to execute a command to place the item M on the predetermined placement area (step S205). Specifically, if the allocation unit 210a becomes ready to place the item M1 on the cell C2 within a certain time after the transport vehicle 100A has stopped near cell C3, which is near cell C2, because the execution of the second transport command has been completed, it is ready to place the item M1 on the cell C2, it requests the communication control unit 220 to notify the transport vehicle 100A to execute a command to place the item M1 on the cell C2. In response to the request from the allocation unit 210a, the communication control unit 220 notifies the transport vehicle 100A to execute a command to place the item M1 on the cell C2.

[0066] On the other hand, if the allocation unit 210a does not make it possible to place the item M on the designated placement area within a certain time after the transport vehicle 100 has stopped near the designated placement area (step S204: NO), it assigns a third transport command to the transport vehicle 100 (step S206). Specifically, if the execution of the second transport command is not completed within a certain time after the transport vehicle 100A has stopped at cell C3, and the item M1 is not made possible to place at the position of cell C2, the allocation unit 210a assigns a third transport command to the transport vehicle 100A, with the position of cell C3 where the transport vehicle 100A has stopped as the transport source and a different position from cell C2 as the transport destination.

[0067] As described above, if the transport system 1 is unable to place the item M1 in cell C2 for a certain period of time or longer, it assigns a third transport command to the transport vehicle 100A, specifying cell C3 as the transport source and a different cell C than cell C2 as the transport destination. This prevents the state in which the item M1 cannot be placed in cell C2 (the designated placement area) from continuing for an extended period of time.

[0068] Although embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. Furthermore, such modified or improved forms are also included in the technical scope of the present invention. One or more of the requirements described in the above embodiments may be omitted. Also, the requirements described in the above embodiments can be combined as appropriate. In addition, the execution order of each process shown in this embodiment can be implemented in any order, as long as the output of the previous process is not used in the subsequent process. Furthermore, even if the operation in the above embodiments is described using "first," "next," "followed," etc. for convenience, it is not necessary to perform them in this order. Furthermore, to the extent permitted by law, the disclosures of Japanese Patent Application No. 2024-222335 and all documents cited in the above embodiments are incorporated into this text.

[0069] 1...Transportation system 100...Transport vehicle 110...Travel control unit 120...Communication control unit 130...Storage unit 200...Controller 210...Assignment unit 220...Communication control unit 230...Storage unit

Claims

1. A transport system comprising: a plurality of transport vehicles that travel along a track to transport goods; and a controller that manages transport commands specifying the source and destination of the goods and assigns the transport commands to each transport vehicle, wherein the controller, when assigning a first transport command to a predetermined loading area as the destination, checks whether a second transport command exists that specifies the predetermined loading area as the source, and if the second transport command exists, assigns the second transport command with priority over the first transport command.

2. The transport system according to claim 1, wherein the controller, in a situation where the candidate to which the first transport command is to be assigned is the first transport vehicle, assigns the second transport command to the first transport vehicle if the second transport command exists, and assigns the first transport command to the first transport vehicle if the second transport command does not exist.

3. The transport system according to claim 2, wherein when the controller assigns the second transport command to the first transport vehicle, it assigns the first transport command to a second transport vehicle different from the first transport vehicle.

4. The transport system according to any one of claims 1 to 3, wherein the controller designates a transport vehicle that is closer to the transport source specified in the transport command, among transport vehicles to which no transport command has been assigned, as a candidate for assignment of the transport command.

5. The transport system according to claim 1, wherein the controller checks whether a second transport command exists when the number of transport vehicles capable of executing the transport command is less than the number of transport commands it manages.

6. The transport system according to claim 1, wherein the controller, if the item is not in a state where it can be placed on the predetermined loading area, assigns to the transport vehicle a first transport command including a command to stop near the predetermined loading area and a command to place the item on the predetermined loading area; if the item becomes in a state where it can be placed on the predetermined loading area within a certain period of time after the transport vehicle has stopped near the predetermined loading area, the controller notifies the transport vehicle to execute the command to place the item on the predetermined loading area; and if the item does not become in a state where it can be placed on the predetermined loading area within a certain period of time after the transport vehicle has stopped near the predetermined loading area, the controller assigns to the transport vehicle a third transport command with the position where the transport vehicle stopped as the source of transport and a position different from the predetermined loading area as the destination.

7. The transport system according to claim 6, wherein if the item is not in a state where it can be placed on the predetermined placement area, including the case where the execution of the assigned second transport command has not been completed, the controller notifies the transport vehicle to execute a command to place the item on the predetermined placement area if the execution of the second transport command is completed within a certain period of time after the transport vehicle has stopped near the predetermined placement area, and assigns the third transport command to the transport vehicle if the execution of the second transport command has not been completed within a certain period of time after the transport vehicle has stopped near the predetermined placement area.

8. The transport system according to claim 7, wherein if the execution of the second transport command is not completed within a certain time after the transport vehicle has stopped near the predetermined mounting section, the controller releases the assignment of the first transport command and then assigns the third transport command to the transport vehicle.

9. The transport system according to claim 1, wherein the track has a plurality of first tracks extending along a first direction and a plurality of second tracks extending along a second direction different from the first direction, and the plurality of first tracks and the plurality of second tracks form a grid-like track that forms a plurality of squares.

10. A transport method in a transport system comprising: a plurality of transport vehicles that travel along a track to transport goods; and a controller that manages transport commands specifying the source and destination of the goods and assigns the transport commands to each transport vehicle, the method comprising: checking whether a second transport command exists that specifies a predetermined loading unit as the source when assigning a first transport command that specifies a predetermined loading unit as the destination; and, if the second transport command exists, assigning the second transport command with priority over the first transport command.

Images