Transport vehicle system

Abstract

A transport vehicle system (1) is provided with a plurality of transport vehicles (5), a plurality of work stations (ST), and a control unit (40). The control unit (40) executes a replacement determination that determines whether or not there is a second transport vehicle (5B) to which a transport command to which a second work station (STb) disposed downstream of the first work station (STa) is to be moved is assigned at a position upstream of the first transport vehicle (5A) to which the transport command to which the first work station (STa) is to be moved is assigned, and performs a replacement determination that determines whether or not there is a second transport vehicle (5B) to which a transport command to which the second work station (STb) disposed downstream of the first work station (STa) is to be moved is assigned at a position upstream of the first transport vehicle (5A). If the control unit (40) determines that the second transport vehicle (5B) is present upstream of the first transport vehicle (5A), the control unit (40) executes replacement control for replacing the movement destinations of the transport commands allocated before the replacement determination between the first transport vehicle (5A) and the second transport vehicle (5B).

Description

Technical Field

[0001] The present invention relates to a transport vehicle system. Background Art

[0002] A transport vehicle system is known, in which a transport vehicle that transports containers such as FOUP (Front Opening Unified Pod) or reticle boxes containing objects such as semiconductor wafers or glass substrates travels along a track (for example, Patent Document 1). The transport vehicle system is configured to include a plurality of transport vehicles that travel on a track whose travel direction is determined to be one direction. Moreover, each of the plurality of transport vehicles is configured to move based on a transport instruction assigned by a controller. The transport instruction includes mobile destination information related to a workstation with a loading request. In such a transport vehicle system, generally speaking, whenever a transport request is generated in a workstation, a transport instruction including the one workstation as the mobile destination information is assigned to the transport vehicle that can arrive at the one workstation earliest.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. WO2017 / 029873 Summary of the invention

[0006] However, in the general control as described above, Figure 5 As shown in the state 5A, when the first transport vehicle 105A traveling on the track 111 is assigned a transport instruction with the first workstation STa as the destination, and the second transport vehicle 105B is assigned a transport instruction with the second workstation STb arranged on the downstream side of the first workstation STa as the destination, and the first transport vehicle 105A travels on the upstream side of the second transport vehicle 105B, the following problem may occur. That is, if Figure 5 As shown in the state 5B, during the period when the first transport vehicle 105A performs the transfer operation of picking up the articles from the first workstation STa, the second transport vehicle 105B must wait behind the first transport vehicle 105A (upstream side) until the transfer operation of the first transport vehicle 105A is completed. Figure 5 As shown in the state 5C, the transfer operation is performed at the second workstation STb as the transfer destination. Such a waiting time of the rear transport vehicle (the second transport vehicle 105B) will reduce the transport efficiency of the transport vehicle system.

[0007] Therefore, an object of one aspect of the present invention is to provide a transport vehicle system capable of improving transport efficiency in the transport vehicle system by reducing the waiting time of a rear transport vehicle due to a transfer operation of a front transport vehicle.

[0008] A transport vehicle system according to one aspect of the present invention comprises: a plurality of transport vehicles that travel in one direction along a predetermined path and transport articles; a plurality of workstations that are arranged along the path and serve as sources of loading requests for articles; and a control unit that, whenever a loading request for articles is generated, assigns a transport instruction that uses the workstation with the loading request as a moving destination to a transport vehicle that can reach the workstation with the loading request the earliest, and the control unit performs the following replacement determination, that is, determining that a transport vehicle that is on the upstream side of a first transport vehicle that is one of the plurality of transport vehicles is on the upstream side of a first transport vehicle that is one of the plurality of transport vehicles. If the control unit determines that there is a second transport vehicle at a position upstream of the first transport vehicle, a replacement control is executed to replace the mobile destinations of the transport instructions assigned before the replacement determination between the first transport vehicle and the second transport vehicle.

[0009] In the transport vehicle system of this structure, by replacing the transport instruction, the waiting time generated when the transport instruction is not replaced, that is, the time the second transport vehicle waits behind (upstream) the first workstation while the first transport vehicle performs the transfer action of collecting items from the first workstation, can be reduced. In addition, when there are other transport vehicles behind the rear transport vehicle, the number of waiting times of the transport vehicle is reduced by one, so that the waiting time is shortened, thereby shortening the length of the waiting vehicle train, thereby further improving the overall transport efficiency of the transport vehicle system. For example, when there is a branch point upstream of the workstation, by shortening the waiting vehicle train, the possibility of the predetermined branched trolley being drawn into the vehicle train can be reduced. As a result, the transport efficiency in the transport vehicle system can be improved.

[0010] In a transport vehicle system according to one aspect of the present invention, it is also possible that, in the replacement determination performed by the control unit, it is determined whether there is a second transport vehicle that, when the first transport vehicle executes a transport instruction with the first workstation as the moving destination, waits upstream of the first transport vehicle until the operation of the first transport vehicle is completed. In this structure, the waiting time of the second transport vehicle when the first transport vehicle located in front of it picks up the transfer action of the article from the workstation can be reliably eliminated. In addition, the second transport vehicle executes the transport instruction with the first workstation as the moving destination without a significant delay from the initial scheduled time when the first transport vehicle should complete the execution.

[0011] In a transport vehicle system according to one aspect of the present invention, it is also possible that, in the replacement determination performed by the control unit, it is determined whether there is a second transport vehicle that can start a transfer operation at the first workstation while the first transport vehicle is performing a transfer operation at the second workstation when the destinations of the transport instructions assigned before the replacement determination are replaced with each other. In this structure, the first transport vehicle and the second transport vehicle can perform transfer to each workstation almost simultaneously. In this case, the transport efficiency of the system as a whole is improved.

[0012] In the transport vehicle system of one aspect of the present invention, when the control unit determines through replacement determination that the second transport vehicle exists at a position upstream of the first transport vehicle, the control unit may also execute replacement control even if there is another transport vehicle between the first transport vehicle and the second transport vehicle. In this structure, the replacement control can be executed even if the second transport vehicle is not located immediately behind the first transport vehicle, so the search range of the transport vehicle to be replaced can be expanded, and the transport vehicle to be replaced can be easily found.

[0013] In a transport vehicle system according to one aspect of the present invention, the control unit may perform a replacement determination when a first transport vehicle assigned a transport instruction with the first workstation as a moving destination reaches a specified position on the upstream side of the first workstation, the specified position being a deceleration start position when the first transport vehicle stops at the first workstation. In this structure, when there is no second transport vehicle to be replaced behind the first transport vehicle, the first transport vehicle can be stopped directly at the first workstation. In addition, the time for executing the determination control can be delayed to the last moment when the first transport vehicle can stop at the first workstation, so that the second transport vehicle is easy to find. In addition, compared with the case where the presence or absence of the second transport vehicle is always determined, the burden on the control unit can be reduced.

[0014] Effects of the Invention

[0015] According to one aspect of the present invention, by reducing the waiting time of the rear transport vehicle due to the transfer operation of the front transport vehicle, the transport efficiency in the transport vehicle system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram showing the structure of a transport vehicle system according to one embodiment.

[0017] Figure 2 This is a functional block diagram showing the functional configuration of the transport vehicle system.

[0018] Figure 3 This is a diagram for explaining replacement determination and replacement control in the transport vehicle system.

[0019] Figure 4 This is a diagram for explaining replacement determination and replacement control in the transport vehicle system.

[0020] Figure 5 This is a diagram for explaining problems that occur in a conventional transport vehicle system. DETAILED DESCRIPTION

[0021] Hereinafter, an embodiment will be described with reference to the accompanying drawings. In the description of the accompanying drawings, the same elements are marked with the same reference numerals, and repeated descriptions are omitted. The dimensional ratios in the accompanying drawings are not necessarily consistent with the dimensional ratios in the description. In addition, when describing an embodiment, upstream and downstream refer to the travel direction (or direction) of the aerial transport vehicle (transport vehicle) 5 (hereinafter, simply referred to as "transport vehicle 5") which is set in advance. Figure 1 The directions of the arrows shown on the track 11 are: upstream and downstream in one direction.

[0022] The transport vehicle system 1 is a system for transporting FOUPs using a transport vehicle 5 that can move along a track 11. The transport vehicle 5 is an unmanned transport vehicle, such as an aerial transport vehicle, a rail-mounted trolley, etc. Here, the transport vehicle system 1 in which the transport vehicle 5 moves along a one-way track 11 laid on the ceiling of a building such as a factory is taken as an example for explanation. Figure 1 As shown, the transport vehicle system 1 mainly includes a rail 11 , a plurality of workstations ST, a plurality of transport vehicles 5 , and a transport vehicle controller (control unit) 3 .

[0023] The rail 11 is a member for allowing the transport vehicle 5 to travel, and is suspended from the ceiling. Figure 1 An example of a layout of a portion of the track 11 in this embodiment is shown. The track 11 in this embodiment is set so that the transport vehicle 5 Figure 1 Traffic is carried out in one direction in the direction of the arrow shown. The track 11 is provided with a branch point BP where the track 11 branches and a merging point CP where the track 11 merges.

[0024] The workstation ST is arranged along the track 11 so as to face the track 11. In the present embodiment, a plurality of workstations ST are provided. The workstation ST is a portion for transferring FOUPs to and from the transport vehicle 5. For example, examples of workstations ST in a semiconductor processing plant include a loading port for transferring FOUPs (articles) between a semiconductor processing device and the transport vehicle 5, and a buffer portion for temporarily placing FOUPs on the transport vehicle 5. The workstation ST is a source of FOUP loading requests.

[0025] like Figure 2 As shown, the transport vehicle controller 3 includes an input unit 31, a display unit 32, a communication unit 33, and a transport vehicle control unit 40. The input unit 31 includes, for example, a keyboard and a mouse, and is a part where the user inputs various operations and various set values. In the present embodiment, information related to the specified position P, which will be described in detail later, is input and set from the input unit 31. The display unit 32 includes, for example, a liquid crystal display, and is a part that displays various setting screens, displays an input screen for inputting using the input unit 31, etc. The input unit 31 and the display unit 32 do not need to be provided integrally with the transport vehicle controller 3, and can be replaced by terminal devices that can communicate with each other.

[0026] The communication unit 33 is a part that communicates with other devices, etc., and transmits a transport instruction to the transport vehicle 5 or receives information (position data) related to the current position of the transport vehicle 5 via, for example, a wireless communication network. In addition, the communication unit 33 also receives a transport instruction including information about the workstation ST that is the destination of the transfer from the host controller via, for example, a LAN (Local Area Network). That is, the host controller transmits information related to the workstation ST that has a transport request to the transport vehicle controller 3.

[0027] The transport vehicle control unit 40 is a part that performs various control processes in the transport vehicle system 1 described in detail later, and is composed of, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. Figure 2 As shown, the transport vehicle control unit 40 can be configured as software in which a program stored in, for example, ROM is loaded onto RAM and executed by the CPU. Alternatively, the transport vehicle control unit 40 can be configured as hardware based on an electronic circuit or the like.

[0028] The transport vehicle control unit 40 assigns a transport instruction to the transport vehicle 5 based on information related to the workstation ST with a loading request, for example, sent from a higher-level controller (not shown). More specifically, whenever a loading request for a FOUP is generated, the transport vehicle control unit 40 assigns a transport instruction with the workstation ST with a loading request as the moving destination to the transport vehicle 5 that can reach the workstation ST with a loading request the earliest and has not been assigned other transport instructions (including transport instructions other than the loading request). In addition, the transport vehicle controller 3 grasps the position of the transport vehicle 5 based on the position information (described in detail later) sent periodically or continuously from each transport vehicle 5. When only "transport instruction" is shown below, it refers to a transport instruction with the workstation ST with a loading request as the moving destination unless otherwise specified.

[0029] The transport vehicle control unit 40 is as follows Figure 3 As shown in the state 3A shown, replacement judgment and replacement control are performed. The replacement judgment is the following judgment, that is, when the first conveying vehicle 5A, which is one of the multiple conveying vehicles 5, arrives at the specified position P on the upstream side of the first workstation STa, it is judged whether the second conveying vehicle 5B, which is a conveying vehicle 5 different from the first conveying vehicle 5A, exists on the upstream side compared with the first conveying vehicle 5A, wherein the first conveying vehicle 5A is assigned a conveying instruction to use the first workstation STa, which is one of the multiple workstations ST, as the moving destination, and the second conveying vehicle 5B is assigned a conveying instruction to use the workstation ST, that is, the second workstation STb, which is arranged on the downstream side of the first workstation STa, as the moving destination. In addition, Figure 3 to Figure 5 The transport vehicle 5 shown in FIG. 5 is assigned a transport instruction to the first workstation STa as a transport destination, and the transport vehicle 5 is assigned a transport instruction to the second workstation STb as a transport destination.

[0030] Here, the predetermined position P is a position separated from the first station STa by a distance D to the upstream side. More specifically, the predetermined position P is a deceleration start position when the first transport vehicle 5A stops at the first station STa. In other words, if the first transport vehicle 5A starts to decelerate from the predetermined position P, it can stop at the first station STa.

[0031] The replacement control is a control in which, if it is determined that the second transport vehicle 5B is located upstream of the first transport vehicle 5A, the moving destination of the transport instruction assigned before the replacement determination is replaced between the first transport vehicle 5A and the second transport vehicle 5B. Figure 3 In the state 3A shown in FIG. 3A, when a transport instruction with the first workstation STa as the moving destination is assigned to the first transport vehicle 5A and a transport instruction with the second workstation STb as the moving destination is assigned to the second transport vehicle 5B, the replacement control is performed. Figure 3As shown in the state 3B shown, the transport instruction with the second workstation STb as the transport destination is reassigned to the first transport vehicle 5A, and the transport instruction with the first workstation STa as the transport destination is reassigned to the second transport vehicle 5B.

[0032] The replacement determination by the transport vehicle control unit 40 is Figure 3 In the state 3A shown, it is determined whether there is a second transport vehicle 5B that can reach the first workstation STa until the first transport vehicle 5A completes the transport instruction with the first workstation STa as the destination. In other words, the above-mentioned replacement determination is to determine whether there is a second transport vehicle 5B that waits upstream of the first transport vehicle 5A until the operation of the first transport vehicle 5A is completed when the first transport vehicle 5A executes the transport instruction with the first workstation STa as the destination. The transport vehicle control unit 40 performs the above-mentioned replacement control when it is determined that there is such a second transport vehicle 5B, and does not perform the above-mentioned replacement control when it is determined that there is no second transport vehicle 5B.

[0033] In addition, the replacement judgment performed by the transport vehicle control unit 40 can also determine whether there is a second transport vehicle 5B as follows, that is, when the moving destinations of the transport instructions assigned before the replacement judgment are replaced with each other, the second transport vehicle 5B can start the transfer action at the first workstation STa while the first transport vehicle 5A is performing the transfer action at the second workstation STb.

[0034] In such a determination, when the above-mentioned replacement control is executed, Figure 4 As shown in the state 4B shown in the figure, a part of the time when the second transport vehicle 5B performs the transfer operation at the second workstation STb can be overlapped with a part of the time when the first transport vehicle 5A performs the transfer operation at the second workstation STb. As a result, the waiting time when the first transport vehicle 5A located in front of the second transport vehicle 5B performs the transfer operation when receiving the FOUP from the workstation ST can be eliminated. In addition, the time when the first transport vehicle 5A performs the transfer operation at the second workstation STb can be completely consistent with the time when the second transport vehicle 5B performs the transfer operation at the second workstation STb.

[0035] When the transport vehicle control unit 40 determines that the second transport vehicle 5B is located upstream of the first transport vehicle 5A through the above-mentioned replacement determination, for example, even if Figure 3The replacement control is also performed even when there are other transport vehicles 5 (two in this embodiment) between the first transport vehicle 5A and the second transport vehicle 5B as in the state 3A shown in FIG. The other transport vehicles 5 mentioned here are, for example, transport vehicles to which no transport instruction is assigned, transport vehicles to which a transport instruction to transport to a workstation other than the workstation to be replaced (the second workstation STb) is assigned, and transport vehicles not holding FOUPs.

[0036] The transport vehicle 5 is configured to be able to transfer FOUPs. In addition to the mechanism for traveling along the track 11 and the known mechanism for transferring FOUPs, the transport vehicle 5 also includes: Figure 2 As shown, the vehicle further includes a position acquisition unit 51 and a travel control unit 53 .

[0037] The position acquisition unit 51 is a part that acquires the position information of the own vehicle on the track 11. The position acquisition unit 51 can be composed of, for example, a reading unit and an encoder that reads a barcode or the like attached to the track 11 and showing the position information. The position acquisition unit 51 sends the point information obtained by the reading unit and the travel distance from the point obtained by the encoder as the position information to the transport vehicle controller 3. The information acquired by the position acquisition unit 51 is sent to the transport vehicle controller 3 in response to periodic or continuous inquiries from the transport vehicle controller 3.

[0038] The travel control unit 53 is a part that controls the travel of the transport vehicle 5, and is an electronic control unit including, for example, a CPU, a ROM, and a RAM. The travel control unit 53 controls the travel of the transport vehicle 5 based on the transport command sent from the transport vehicle controller 3. The transport command sent from the upper controller (not shown) includes information related to the workstation ST with a loading request as the moving destination. The travel control unit 53 controls each mechanism to move to the workstation ST with a loading request as the moving destination included in the above-mentioned transport command and collect FOUP.

[0039] The transport command sent from the transport vehicle controller 3 may include information on the workstation ST as the transport destination of the FOUP. The travel control unit 53 controls each mechanism so as to move to the workstation ST as the transport destination.

[0040] Next, the operation of the transport vehicle system 1 when the above-described replacement determination and replacement control are executed will be described.

[0041] The transport vehicle controller 3 (transport vehicle control unit 40) is as follows: Figure 3When the first transport vehicle 5A assigned a transport instruction with the first workstation STa having a loading request as the destination arrives at the predetermined position P on the upstream side of the first workstation STa as shown in the state 3A, the above replacement determination is performed. Here, if the transport vehicle controller 3 determines that there is a second transport vehicle 5B assigned a transport instruction with the second workstation STb as the destination at a position upstream of the first transport vehicle 5A assigned a transport instruction with the first workstation STa as the destination, the replacement determination is performed as follows: Figure 3 As shown in the state 3B, the destinations of the transport instructions assigned before the replacement determination are replaced between the first transport vehicle 5A and the second transport vehicle 5B. That is, the transport vehicle controller 3 reassigns the transport instruction with the second workstation STb as the destination to the first transport vehicle 5A, and reassigns the transport instruction with the first workstation STa as the destination to the second transport vehicle 5B.

[0042] The first transport vehicle 5A to which the transport instruction with the second workstation STb as the transfer destination is newly assigned is as follows: Figure 4 As shown in the state 4A and state 4B, the first transport vehicle 5A passes through the first workstation STa and stops at the second workstation STb. The first transport vehicle 5A performs a transfer operation to receive the FOUP from the second workstation STb. The second transport vehicle 5B, to which the transport instruction with the first workstation STa as the transfer destination is newly assigned, stops at the first workstation STa. The second transport vehicle 5B performs a transfer operation to receive the FOUP from the first workstation STa.

[0043] In addition, Figure 3 In state 3A, when the transport vehicle controller 3 determines that the second transport vehicle 5B assigned the transport instruction with the second workstation STb as the moving destination does not exist at a position upstream of the first transport vehicle 5A assigned the transport instruction with the first workstation STa as the moving destination, the first transport vehicle 5A stops at the first workstation STa based on the transport instruction and performs the transfer action of picking up the FOUP from the first workstation STa.

[0044] The effects of the transport vehicle system 1 of the above embodiment are described. In the transport vehicle system 1 of the above embodiment, by replacing the transport instructions between the first transport vehicle 5A and the second transport vehicle 5B, the waiting time of the second transport vehicle 5B (i.e., the time the second transport vehicle 5B waits behind the first workstation STa while the first transport vehicle 5A performs the transfer operation of receiving the FOUP from the first workstation STa) that would otherwise occur can be reduced. In addition, when there are other transport vehicles 5 behind the second transport vehicle 5B, the number of waiting times of the transport vehicle 5 is reduced by one, so the overall transport efficiency of the transport vehicle system 1 is further improved. As a result, the transport efficiency in the transport vehicle system 1 can be improved.

[0045] In the transport vehicle system 1 of the above-described embodiment, the replacement determination by the transport vehicle control unit 40 determines whether there is a second transport vehicle 5B that waits upstream of the first transport vehicle 5A until the operation of the first transport vehicle 5A is completed when the first transport vehicle 5A executes a transport instruction with the first workstation STa as the transfer destination. This can eliminate the waiting time of the first transport vehicle 5A located ahead of the second transport vehicle 5B when it receives the FOUP from the workstation STa.

[0046] In the transport vehicle system 1 of the above-described embodiment, when the transport vehicle control unit 40 determines through replacement determination that the second transport vehicle 5B exists at a position upstream of the first transport vehicle 5A, the transport vehicle control unit 40 performs replacement control even if there is another transport vehicle 5 between the first transport vehicle 5A and the second transport vehicle 5B. Thus, even if the second transport vehicle 5B is not located immediately behind the first transport vehicle 5A, the replacement control can be performed, so that the search range of the transport vehicle 5 to be replaced can be expanded, and the transport vehicle 5 to be replaced can be easily found.

[0047] In the transport vehicle system 1 of the above-mentioned embodiment, the predetermined position P is set to be the deceleration start position when the first transport vehicle 5A stops at the first workstation STa. Thus, when there is no second transport vehicle 5B to be replaced behind the first transport vehicle 5A, the first transport vehicle 5A can be stopped directly at the first workstation STa. In addition, the time for executing the determination control can be delayed to the last moment when the first transport vehicle 5A can stop at the first workstation STa, so that the second transport vehicle 5B can be easily found. In addition, compared with the case where the presence or absence of the second transport vehicle 5B is always determined, the processing burden of the transport vehicle control unit 40 can be reduced.

[0048] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0049] In the above embodiment, an example of arranging behind the first transport vehicle 5A is cited as an example for explanation, but the present invention is not limited to this. For example, when there is a merging point CP on the upstream side (rear) of the first transport vehicle 5A, the transport vehicle control unit 40 searches all tracks 11 on the upstream side of the merging point CP to determine whether there is a transport vehicle 5 serving as the second transport vehicle 5B.

[0050] In the above-mentioned embodiment and the above-mentioned modification example, Figure 3 and Figure 4 In the embodiment, there is no branch point BP or the like on the track 11 that reaches the first station STa, but the present invention is not limited thereto. A merging point CP may exist before and after the predetermined position P, and there may be a branch point BP not shown.

[0051] In the above-mentioned embodiment and the above-mentioned modification example, Figure 3 and Figure 4 In the above description, an example in which two transport vehicles 5 are provided between the first transport vehicle 5A and the second transport vehicle 5B is cited, but the present invention is not limited thereto. For example, one transport vehicle 5 may be provided between the first transport vehicle 5A and the second transport vehicle 5B, or no transport vehicle 5 may be provided.

[0052] The above embodiment and the above modification examples illustrate an example in which the transport vehicle control unit 40 performs the above replacement determination when the first transport vehicle 5A reaches the predetermined position P, but the replacement determination may be performed regularly every T seconds, for example. In this case, the transport vehicle control unit 40 performs the following replacement determination, that is, when the transport vehicle 5 serving as the first transport vehicle 5A reaches the predetermined position P within T seconds, it is determined whether the second transport vehicle 5B exists.

[0053] In the above-mentioned embodiment and modification, the example in which the prescribed position P is set only for the first workstation STa which is the most upstream of the arrangement of the workstations ST is described, but the invention is not limited thereto. For example, when there is another workstation ST at a position downstream of the second workstation STb and it is desired to replace the loading request between the second workstation STb and the other workstation ST, the prescribed position P of the second workstation STb is also set for the second workstation STb.

[0054] In the above-described embodiment and modified examples, the FOUP is described as an example of the article, but a container such as a reticle cassette for storing a glass substrate, a general component, or the like may also be used.

[0055] In the transport vehicle system 1 of the above-described embodiment and modified example, the overhead transport vehicle 5 is described as an example of a transport vehicle. However, other examples of transport vehicles include unmanned transport vehicles that travel on rails disposed on the ground or on a platform.

[0056] The technical subject matter of one aspect of the present invention can be described as follows. [1]

[0058] A transport vehicle system, comprising:

[0059] A plurality of transport vehicles, the plurality of transport vehicles travel in one direction along a predetermined path and transport articles;

[0060] a plurality of workstations disposed along the path and serving as a source of loading requests for the items; and

[0061] a control unit that, whenever a loading request for the article is generated, assigns a transport instruction to the transport vehicle that can reach the workstation with the loading request the earliest, with the transport instruction having the workstation with the loading request as a moving destination;

[0062] The control unit performs the following replacement determination, i.e., determining whether there is a second transport vehicle which is different from the first transport vehicle at a position upstream of a first transport vehicle which is one of the plurality of transport vehicles, wherein the first transport vehicle is assigned a transport instruction to use a first workstation which is one of the plurality of workstations as a moving destination, and the second transport vehicle is assigned a transport instruction to use a second workstation which is the workstation arranged on the downstream side of the first workstation as a moving destination,

[0063] When the control unit determines that the second transport vehicle is located upstream of the first transport vehicle, the control unit performs a replacement control for replacing the movement destination of the transport command assigned before the replacement determination between the first transport vehicle and the second transport vehicle. [2]

[0065] According to the transport vehicle system described in [1], wherein, in the replacement judgment performed by the control unit, it is determined whether there is a second transport vehicle as follows, that is, when the first transport vehicle executes a transport instruction with the first workstation as the moving destination, the second transport vehicle waits upstream of the first transport vehicle until the operation of the first transport vehicle is completed. [3]

[0067] A transport vehicle system according to [1] or [2], wherein, in the replacement judgment performed by the control unit, it is determined whether there is a second transport vehicle as follows, that is, when the moving destinations of the transport instructions assigned before the replacement judgment are replaced with each other, the second transport vehicle can start the transfer action at the first workstation while the first transport vehicle is performing the transfer action at the second workstation. [4]

[0069] A transport vehicle system according to any one of [1] to [3], wherein when the control unit determines through the replacement judgment that the second transport vehicle exists at a position upstream of the first transport vehicle, the control unit performs the replacement control even if there is another transport vehicle between the first transport vehicle and the second transport vehicle. [5]

[0071] The transport vehicle system according to any one of [1] to [4], wherein the control unit performs the replacement determination when the first transport vehicle assigned with the transport instruction to use the first workstation as the moving destination arrives at a predetermined position on the upstream side of the first workstation,

[0072] The predetermined position is a deceleration start position when the first transport vehicle stops at the first workstation.

[0073] Description of Reference Numerals

[0074] 1: transport vehicle system, 3: transport vehicle controller (control unit), 5: transport vehicle, 5A: first transport vehicle, 5B: second transport vehicle, 11: track, 40: transport vehicle control unit, P: specified position, ST: workstation, STa: first workstation, STb: second workstation.

Claims

1. A transport vehicle system, wherein: have: A plurality of transport vehicles, the plurality of transport vehicles travel in one direction along a predetermined path and transport articles; a plurality of workstations disposed along the path and serving as a source of loading requests for the items; as well as a control unit that, whenever a loading request for the article is generated, assigns a transport instruction to the transport vehicle that can reach the workstation with the loading request the earliest, with the transport instruction having the workstation with the loading request as a moving destination; The control unit performs the following replacement determination, i.e., determining whether there is a second transport vehicle which is different from the first transport vehicle at a position upstream of a first transport vehicle which is one of the plurality of transport vehicles, wherein the first transport vehicle is assigned a transport instruction to use a first workstation which is one of the plurality of workstations as a moving destination, and the second transport vehicle is assigned a transport instruction to use a second workstation which is the workstation arranged on the downstream side of the first workstation as a moving destination, When the control unit determines that the second transport vehicle is located upstream of the first transport vehicle, the control unit performs a replacement control for replacing the movement destination of the transport command assigned before the replacement determination between the first transport vehicle and the second transport vehicle.

2. The transport vehicle system according to claim 1, wherein: In the replacement judgment performed by the control unit, it is determined whether there is a second transport vehicle that, when the first transport vehicle executes a transport instruction with the first workstation as the moving destination, waits upstream of the first transport vehicle until the operation of the first transport vehicle is completed.

3. The transport vehicle system according to claim 1, wherein: In the replacement judgment performed by the control unit, it is determined whether there is the following second transport vehicle, that is, when the moving destinations of the transport instructions assigned before the replacement judgment are replaced with each other, the second transport vehicle can start the transfer action at the first workstation while the first transport vehicle is performing the transfer action at the second workstation.

4. The transport vehicle system according to any one of claims 1 to 3, wherein: When the control unit determines through the replacement determination that the second transport vehicle is present upstream of the first transport vehicle, the control unit executes the replacement control even if another transport vehicle is present between the first transport vehicle and the second transport vehicle.

5. The transport vehicle system according to any one of claims 1 to 3, wherein: The control unit executes the replacement determination when the first transport vehicle to which the transport instruction for moving the first workstation is assigned arrives at a predetermined position on the upstream side of the first workstation. The predetermined position is a deceleration start position when the first transport vehicle stops at the first workstation.

Images