Goods transport equipment

Abstract

To provide a technique that can reduce the time required for handover between access points belonging to different network segments from each other, thereby suppressing the reduction in article conveyance efficiency associated with such handover.SOLUTION: When switching from a state in which a transport vehicle 1 is connected to any of access points constituting a first access point group to a state in which the transport vehicle 1 is connected to any of access points constituting a second access point group, or switching from a state in which the transport vehicle 1 is connected to any of the access points constituting the second access point group to a state in which the transport vehicle 1 is connected to any of the access points constituting the first access point group, a higher-level control unit 14 executes a network segment switching process that restarts a communication control unit 12 and a protocol stack 13 while maintaining the startup state of a physical layer device 11.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an article transport facility that includes a transport vehicle that travels along a specified travel route to transport articles, a control device that controls the transport vehicle, and communication equipment that connects the transport vehicle and the control device so that they can communicate with each other. [Background technology]

[0002] An example of such an article conveying facility is disclosed in Japanese Patent Laid-Open Publication No. 2018-36867 (Patent Document 1). Hereinafter, in the description of the background art, reference numerals in Patent Document 1 will be cited in parentheses. The article conveying facility of Patent Document 1 includes an unmanned autonomous vehicle (2) that travels on tracks (1, 4) to convey an article (8), a control device (30) that controls the unmanned autonomous vehicle (2), and communication equipment that connects the unmanned autonomous vehicle (2) and the control device (30) so that they can communicate with each other. The communication equipment includes base stations (A1, A2) that are installed so that they can communicate with the unmanned autonomous vehicle (2), and a LAN (10) that connects the multiple base stations (A1, A2). The base stations (A1, A2) are configured to relay communication between the control device (30) and the unmanned autonomous vehicle (2) via communication links (L1, L2) with the unmanned autonomous vehicle (2) and the LAN (10). As the unmanned vehicle (2) travels, roaming is performed, which is the switching of base stations (A1, A2) with which the communication links (L1, L2) are established. Patent Document 1 discloses a technology for reducing the time required for roaming. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-36867 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when a communication network has multiple network segments, handover (handoff), which is switching of access points (base stations in Patent Document 1) with which a communication link is established, is performed not only between access points belonging to the same network segment as in the roaming in Patent Document 1, but also between access points belonging to different network segments. From the viewpoint of the efficiency of transporting goods by transport vehicles (unmanned vehicles in Patent Document 1), it is desirable to keep the time required for handover between access points belonging to different network segments short, but Patent Document 1 is silent on this point.

[0005] Therefore, it is desirable to realize a technology that can reduce the time required for handover between access points that belong to different network segments and suppress the decrease in the efficiency of transporting goods that accompanies the handover. [Means for solving the problem]

[0006] An article transport facility according to the present disclosure is an article transport facility comprising a transport vehicle that travels along a specified travel route to transport articles, a control device that controls the transport vehicle, and a communication facility that connects the transport vehicle and the control device so that they can communicate with each other, wherein the communication facility comprises a plurality of wireless communication access points installed so as to be able to communicate with the transport vehicle, and a communication network that connects the plurality of access points, wherein an access point group consisting of some of the plurality of access points is defined as a first access point group, and an access point group consisting of a plurality of access points different from the first access point group is defined as a second access point group, and the communication network comprises a first network segment that connects the plurality of access points that make up the first access point group, and a second network segment that connects the plurality of access points that make up the second access point group, and the transport vehicle communicates with the wireless communication device and the access point selected from the plurality of access points via the wireless communication device. and a communication unit that communicates with an access point, the communication unit comprising: a physical layer device that controls a connection with the wireless communication device; a communication control unit that processes data sent and received via the physical layer device and controls communication; a protocol stack having a communication protocol for communication via the communication network; and an upper control unit that controls the physical layer device, the communication control unit, and the protocol stack, wherein the upper control unit executes a network segment switching process that restarts the communication control unit and the protocol stack while maintaining the activation state of the physical layer device when switching from a state in which the guided vehicle is connected to an access point that constitutes the first access point group to a state in which the guided vehicle is connected to an access point that constitutes the second access point group, or when switching from a state in which the guided vehicle is connected to an access point that constitutes the second access point group to a state in which the guided vehicle is connected to an access point that constitutes the first access point group.

[0007] In this configuration, a network segment switching process is executed when switching from a state in which the guided vehicle is connected to an access point constituting a first access point group (in other words, an access point belonging to the first network segment) to a state in which the guided vehicle is connected to an access point constituting a second access point group (in other words, an access point belonging to the second network segment), or when switching from a state in which the guided vehicle is connected to an access point constituting the second access point group to a state in which the guided vehicle is connected to an access point constituting the first access point group. That is, in this configuration, a network segment switching process is executed when handover is performed between access points belonging to different network segments. Here, the access point to which the guided vehicle was connected before the handover was executed is referred to as the pre-switching access point, and the access point to which the guided vehicle is connected after the handover was executed is referred to as the post-switching access point.

[0008] In this configuration, the network segment switching process restarts the communication control unit and the protocol stack while maintaining the activation state of the physical layer device. In this way, the network segment switching process restarts the communication control unit and the protocol stack, allowing for proper handover. Specifically, restarting the communication control unit allows for proper deletion of communication data with the pre-switching access point and initialization of the communication control unit, and restarting the protocol stack allows for proper switching of the identification information of the transport vehicle to identification information (e.g., IP address) that enables communication with the post-switching access point. Meanwhile, the network segment switching process maintains the activation state of the physical layer device, eliminating the need for re-establishing a communication link between the physical layer device and the wireless communication device (specifically, the physical layer device of the wireless communication device), which would be required if the physical layer device were restarted. This reduces the time required for handover.

[0009] As described above, this configuration can shorten the time required for handover between access points belonging to different network segments. Furthermore, because this time can be shortened, even when the movement of the transport vehicle involves handover between access points belonging to different network segments, it is possible to prevent a prolonged state in which communication between the control device and the transport vehicle is not possible, and to suppress a decrease in the efficiency of transporting goods due to the handover.

[0010] Further features and advantages of the article transport installation will become apparent from the following description of the embodiments, which is given with reference to the drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an article transport facility according to an embodiment in a simplified manner; [Figure 2] Conceptual diagram of an article transport facility according to an embodiment [Figure 3] Control block diagram according to an embodiment DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of an article conveying facility will be described with reference to the drawings. As shown in Figs. 1 and 2, the article conveying facility 100 includes a transport vehicle 1 that travels along a specified travel route 60 to transport an article 2, a control device 50 that controls the transport vehicle 1, and a communication facility 3 that connects the transport vehicle 1 and the control device 50 so that they can communicate with each other. In this embodiment, the article conveying facility 100 includes multiple transport vehicles 1, and the control device 50 controls the multiple transport vehicles 1 via the communication facility 3. The article 2 is, for example, a FOUP (Front Opening Unified Pod) that contains semiconductor wafers.

[0013] The travel path 60 may be formed physically or may be set virtually. For example, the travel path 60 is formed physically by rails. When the travel path 60 is formed by rails suspended from a ceiling, the transport vehicle 1 is a ceiling transport vehicle that travels along the travel path 60 formed along the ceiling. The transport vehicle 1 may also be an article transport vehicle other than a ceiling transport vehicle. An example of an article transport vehicle other than a ceiling transport vehicle is an article transport vehicle that travels along the travel path 60 formed along the floor. In this case, the travel path 60 may be formed physically by rails or may be set virtually.

[0014] The control device 50 is equipped with a processing device such as a CPU (Central Processing Unit) and peripheral circuits such as a memory, and the functions of the control device 50 are realized by cooperation between these hardware and programs executed on the hardware such as the processing device. The control device 50 outputs a transport command for the item 2 to the transport vehicle 1. The control device 50 outputs a transport command to the transport vehicle 1, for example, based on a transport schedule or in response to the occurrence of a transport request. The transport command includes information on the origin and destination of the item 2. The origin and destination of the item 2 are, for example, a load port of a processing device that processes the item 2 (or the contents contained in the item 2), a storage shelf that stores the item 2, or an entry / exit section (a loading table, a conveyor, etc.) for the item 2 in a storage device that stores the item 2.

[0015] In response to a transport command from the control device 50, the transport vehicle 1 transports the item 2 from the origin to the destination specified in the transport command. At this time, the transfer operation of the item 2 by the transport vehicle 1 at the origin and the destination (specifically, the operation of receiving the item 2 at the origin and the operation of handing over the item 2 at the destination) and the traveling operation of the transport vehicle 1 from the origin to the destination are controlled by a control unit (not shown) provided in the transport vehicle 1. The control unit provided in the transport vehicle 1 controls the driving of a drive unit such as an electric motor, thereby causing the transport vehicle 1 to perform the transfer operation and traveling operation.

[0016] As shown in Figure 1, the article conveying facility 100 of this embodiment is configured to perform inter-building conveyance, which is the conveyance of an article 2 between different buildings. Therefore, the travel route 60 includes a first route 61 arranged in a first building 71, a second route 62 arranged in a second building 72 (a building different from the first building 71), and a connecting route 63 connecting the first route 61 and the second route 62. When the source of the article 2 is one of the first building 71 and the second building 72 and the destination of the article 2 is the other of the first building 71 and the second building 72, inter-building conveyance is performed between the first building 71 and the second building 72.

[0017] As shown schematically in Fig. 2, the communication equipment 3 includes a plurality of wireless communication access points 30 installed to be able to communicate with the guided vehicle 1 (specifically, to be able to communicate wirelessly), and a communication network 40 connecting the plurality of access points 30. The guided vehicle 1 is communicatively connected to the access point 30 by establishing a communication link with the access point 30. A control device 50 is also connected to the communication network 40, and the access point 30 relays communication between the control device 50 and the guided vehicle 1 via the communication link with the guided vehicle 1 and the communication network 40. The communication network 40 may be wired, wireless, or a combination thereof.

[0018] 2, the communication network 40 includes a first network segment 41 and a second network segment 42. Here, an access point group formed of some of the plurality of access points 30 is referred to as a first access point group 31, and an access point group formed of a plurality of access points 30 different from the first access point group 31 (in other words, an access point group formed of a plurality of access points 30 that are not part of the first access point group 31) is referred to as a second access point group 32. The first network segment 41 connects the plurality of access points 30 that make up the first access point group 31, and the second network segment 42 connects the plurality of access points 30 that make up the second access point group 32.

[0019] 1 does not show the access points 30 and the communication network 40, but in this embodiment, a first access point group 31 is made up of a plurality of access points 30 arranged in a first building 71, and a second access point group 32 is made up of a plurality of access points 30 arranged in a second building 72. Therefore, a guided vehicle 1 traveling on a first route 61 is connected to any one of the access points 30 that make up the first access point group 31, and a guided vehicle 1 traveling on a second route 62 is connected to any one of the access points 30 that make up the second access point group 32.

[0020] Note that the communication network 40 may include one or more network segments other than the first network segment 41 and the second network segment 42. For example, if the communication network 40 includes a third network segment other than the first network segment 41 and the second network segment 42, the third network segment connects between a plurality of access points 30 that constitute a third access point group. Here, the third access point group is an access point group that is made up of a plurality of access points 30 that are different from both the first access point group 31 and the second access point group 32 (in other words, an access point group that is made up of a plurality of access points 30 that are not part of either the first access point group 31 or the second access point group 32).

[0021] In this embodiment, the control device 50 includes a first communication server 51 and a second communication server 52. In the example shown in Fig. 2, the first communication server 51 and the second communication server 52 are connected to each other via a communication network 40 so as to be able to communicate with each other.

[0022] The first network segment 41 is configured to connect the first communication server 51 and a plurality of access points 30 that make up the first access point group 31. When the guided vehicle 1 is connected to the access points 30 that make up the first access point group 31 (in other words, the access points 30 that belong to the first network segment 41), the guided vehicle 1 is communicably connected to the first communication server 51, thereby becoming able to communicate with the control device 50.

[0023] The second network segment 42 is configured to connect the second communication server 52 with a plurality of access points 30 that make up the second access point group 32. When the guided vehicle 1 is connected to the access points 30 that make up the second access point group 32 (in other words, the access points 30 that belong to the second network segment 42), the guided vehicle 1 is communicably connected to the second communication server 52, thereby becoming able to communicate with the control device 50.

[0024] As shown in FIG. 3, the transport vehicle 1 includes a wireless communication device 20 and a communication unit 10 that communicates with an access point 30 selected from a plurality of access points 30 via the wireless communication device 20. The wireless communication device 20 functions as a wireless station that performs wireless communication with the access point 30. The wireless communication device 20 establishes a communication link with the selected access point 30 (e.g., the access point 30 with the highest signal strength), thereby becoming communicatively connected to the selected access point 30. The wireless communication device 20 includes a communication module that can perform wireless communication with the access point 30. This communication module is, for example, a module that performs wireless communication in accordance with a wireless LAN (Local Area Network) communication standard.

[0025] The communication unit 10 includes a first physical layer device 11, a communication control unit 12, a protocol stack 13, and an upper control unit 14. These elements of the communication unit 10 are mounted on, for example, a single board. The upper control unit 14 controls the first physical layer device 11, the communication control unit 12, and the protocol stack 13. A processor such as a CPU (Central Processing Unit) included in the upper control unit 14 executes the protocol stack 13, which is software. Note that the elements of the communication unit 10 are at least functionally or logically distinct, and do not necessarily need to be physically distinct. For example, the first physical layer device 11 and the communication control unit 12 may be integrated into a common device rather than being independent devices. Furthermore, for example, the communication control unit 12 and the upper control unit 14 (specifically, a processor such as a CPU) may be integrated into a common device rather than being independent devices.

[0026] The first physical layer device 11 controls the connection between the communication unit 10 and the wireless communication device 20. The first physical layer device 11 is communicatively connected to a second physical layer device 21 included in the wireless communication device 20. The first physical layer device 11 and the second physical layer device 21 are devices (chips) that perform physical layer processing and convert between logical signals and electrical signals. Here, the first physical layer device 11 and the second physical layer device 21 are connected by wire (for example, by a wired LAN cable). Upon startup, the first physical layer device 11 performs processing (link-up processing) to establish a communication link with the second physical layer device 21. The link-up processing is, for example, auto-negotiation processing that automatically sets the communication speed and communication mode (half-duplex, full-duplex). In this embodiment, the first physical layer device 11 corresponds to the "physical layer device."

[0027] The communication control unit 12 processes data transmitted and received via the first physical layer device 11 and controls communication. The communication control unit 12 is a device (chip) that executes processing of the data link layer, and is connected to the first physical layer device 11 via a data bus (not shown). The communication control unit 12 processes, transmits, and receives packets, thereby controlling communication and processing of data transmitted and received via the first physical layer device 11. The communication control unit 12 is realized by, for example, a LAN controller (specifically, a wired LAN controller).

[0028] Protocol stack 13 includes a communication protocol for communication via communication network 40. The communication protocol included in protocol stack 13 is, for example, TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). Protocol stack 13 issues a command to communication control unit 12 to send data according to the communication protocol. Protocol stack 13 also converts data received by communication control unit 12 via first physical layer device 11 and passes the converted data to an application.

[0029] Identification information of the guided vehicle 1 is used for communication between the guided vehicle 1 and the control device 50. In this embodiment, the identification information is an IP (Internet Protocol) address. The identification information of the guided vehicle 1 (here, the IP address) is held in the protocol stack 13 of the communication unit 10 provided in the guided vehicle 1. As described above, the communication network 40 includes a first network segment 41 and a second network segment 42. A network segment is a network unit separated by a network address. Therefore, the IP address that can communicate with the access point 30 belonging to the first network segment 41 is different from the IP address that can communicate with the access point 30 belonging to the second network segment 42, and different IP addresses are assigned to the guided vehicles 1 in the first network segment 41 and the second network segment 42.

[0030] As the guided vehicle 1 travels, a handover (handoff) is performed, which is a change of the access point 30 with which the wireless communication device 20 provided in the guided vehicle 1 establishes a communication link. When a handover is performed between access points 30 belonging to the same network segment (in FIG. 2, the travel of the guided vehicle 1 accompanied by such a handover is indicated by a first arrow M1), the IP address of the guided vehicle 1 is not changed. Therefore, the upper control unit 14 performs a handover between access points 30 belonging to the same network segment while maintaining the activation states of the first physical layer device 11, the communication control unit 12, and the protocol stack 13.

[0031] On the other hand, when a handover is performed between access points 30 belonging to different network segments (in FIG. 2, the travel of the guided vehicle 1 accompanied by such a handover is indicated by a second arrow M2), the IP address of the guided vehicle 1 is changed. In this embodiment, a handover between access points 30 belonging to different network segments includes a first switching and a second switching. Here, the first switching is a switching from a state in which the guided vehicle 1 is connected to an access point 30 constituting the first access point group 31 to a state in which the guided vehicle 1 is connected to an access point 30 constituting the second access point group 32. Furthermore, the second switching is a switching from a state in which the guided vehicle 1 is connected to an access point 30 constituting the second access point group 32 to a state in which the guided vehicle 1 is connected to an access point 30 constituting the first access point group 31. In this embodiment, the first switching and the second switching are performed when the guided vehicle 1 travels along the connection path 63 and moves from one of the first building 71 and the second building 72 to the other (see FIG. 1).

[0032] In this way, when a handover is performed between access points 30 belonging to different network segments, if the first physical layer device 11 is restarted (reset), the communication link between the first physical layer device 11 and the second physical layer device 21 is disconnected. Therefore, a process (link-up process) is required to re-establish the communication link between the first physical layer device 11 and the second physical layer device 21, and this link-up process usually takes a certain amount of time. As a result, the time required for the handover becomes longer, which may cause a traffic jam of the guided vehicles 1 on the connection path 63, for example.

[0033] In view of this, in the article conveying facility 100 of the present disclosure, when performing the first switching or the second switching (in the present embodiment, when performing both the first switching and the second switching), the upper control unit 14 executes a network segment switching process to restart the communication control unit 12 and the protocol stack 13 while maintaining the activated state of the first physical layer device 11. That is, the upper control unit 14 executes the network segment switching process when performing a handover between access points 30 belonging to different network segments. Here, the access point 30 to which the guided vehicle 1 (specifically, the wireless communication device 20) was connected before the handover is referred to as the "pre-switching access point," and the access point 30 to which the guided vehicle 1 (specifically, the wireless communication device 20) is connected after the handover is referred to as the "post-switching access point."

[0034] In the network segment switching process, restarting the communication control unit 12 allows the communication data with the previous access point to be properly deleted and the communication control unit 12 to be initialized, and restarting the protocol stack 13 allows the IP address of the guided vehicle 1 to be properly switched to an IP address that allows communication with the new access point. Restarting the communication control unit 12 and the protocol stack 13 does not involve a process that requires a relatively long time, such as the link-up process described above. On the other hand, since the network segment switching process maintains the activated state of the first physical layer device 11 (i.e., the communication link between the first physical layer device 11 and the second physical layer device 21 is maintained), the link-up process that would be required when the first physical layer device 11 is restarted is not required, and the time required for handover can be shortened. As a result, even if the movement of the guided vehicle 1 involves handover between access points 30 belonging to different network segments, it is possible to prevent a state in which communication between the control device 50 and the guided vehicle 1 is not maintained for a long time, and to suppress a decrease in the efficiency of transporting the article 2 that occurs due to the handover.

[0035] Note that, although an example has been described here in which the first access point group 31 is made up of a plurality of access points 30 arranged in the first building 71 and the second access point group 32 is made up of a plurality of access points 30 arranged in the second building 72, the present invention is not limited to this. For example, when the article conveying facility 100 is configured to perform interfloor conveyance, which is conveyance of articles 2 between different floors in the same building, the first access point group 31 may be made up of a plurality of access points 30 arranged on the first floor, and the second access point group 32 may be made up of a plurality of access points 30 arranged on the second floor (a floor different from the first floor). In this case, the conveying vehicle 1 moves between the travel path 60 arranged on the first floor and the travel path 60 arranged on the second floor by, for example, being raised and lowered by an elevator device.

[0036] The embodiments disclosed in this specification are merely examples in all respects, and various modifications can be made as appropriate within the scope of the present disclosure.

[0037] [Summary of the above embodiment] An outline of the article transport facility described above will now be described.

[0038] an access point group consisting of a part of the plurality of access points is defined as a first access point group, and an access point group consisting of a plurality of access points different from the first access point group is defined as a second access point group; the communication network comprises a first network segment connecting the plurality of access points that constitute the first access point group, and a second network segment connecting the plurality of access points that constitute the second access point group; and the transport vehicle communicates with a wireless communication device, and the transport vehicle communicates with an access point selected from the plurality of access points via the wireless communication device. and a communication unit for communicating with the wireless communication device, the communication unit comprising: a physical layer device that controls the connection with the wireless communication device; a communication control unit that processes data sent and received via the physical layer device and controls communication; a protocol stack having a communication protocol for communication via the communication network; and an upper control unit that controls the physical layer device, the communication control unit, and the protocol stack, wherein when switching from a state in which the guided vehicle is connected to an access point that constitutes the first access point group to a state in which the guided vehicle is connected to an access point that constitutes the second access point group, or when switching from a state in which the guided vehicle is connected to an access point that constitutes the second access point group to a state in which the guided vehicle is connected to an access point that constitutes the first access point group, the upper control unit executes a network segment switching process that restarts the communication control unit and the protocol stack while maintaining the startup state of the physical layer device.

[0039] In this configuration, a network segment switching process is executed when switching from a state in which the guided vehicle is connected to an access point constituting a first access point group (in other words, an access point belonging to the first network segment) to a state in which the guided vehicle is connected to an access point constituting a second access point group (in other words, an access point belonging to the second network segment), or when switching from a state in which the guided vehicle is connected to an access point constituting the second access point group to a state in which the guided vehicle is connected to an access point constituting the first access point group. That is, in this configuration, a network segment switching process is executed when handover is performed between access points belonging to different network segments. Here, the access point to which the guided vehicle was connected before the handover was executed is referred to as the pre-switching access point, and the access point to which the guided vehicle is connected after the handover was executed is referred to as the post-switching access point.

[0040] In this configuration, the network segment switching process restarts the communication control unit and the protocol stack while maintaining the activation state of the physical layer device. In this way, the network segment switching process restarts the communication control unit and the protocol stack, allowing for proper handover. Specifically, restarting the communication control unit allows for proper deletion of communication data with the pre-switching access point and initialization of the communication control unit, and restarting the protocol stack allows for proper switching of the identification information of the transport vehicle to identification information (e.g., IP address) that enables communication with the post-switching access point. Meanwhile, the network segment switching process maintains the activation state of the physical layer device, eliminating the need for re-establishing a communication link between the physical layer device and the wireless communication device (specifically, the physical layer device of the wireless communication device), which would be required if the physical layer device were restarted. This reduces the time required for handover.

[0041] As described above, this configuration can shorten the time required for handover between access points belonging to different network segments. Furthermore, because this time can be shortened, even when the movement of the transport vehicle involves handover between access points belonging to different network segments, it is possible to prevent a prolonged state in which communication between the control device and the transport vehicle is not possible, and to suppress a decrease in the efficiency of transporting goods due to the handover.

[0042] Here, it is preferable that the control device comprises a first communication server and a second communication server, the first network segment is configured to connect the first communication server and a plurality of the access points that constitute the first access point group, and the second network segment is configured to connect the second communication server and a plurality of the access points that constitute the second access point group.

[0043] According to this configuration, when the transport vehicle is connected to an access point belonging to the first network segment, the transport vehicle and the first communication server can be communicatively connected, and when the transport vehicle is connected to an access point belonging to the second network segment, the transport vehicle and the second communication server can be communicatively connected. As described above, in the article transport equipment disclosed herein, the time required for handover between access points belonging to different network segments can be kept short, so that the transport vehicle can be prevented from being unable to communicate with either the first communication server or the second communication server for a long period of time.

[0044] It is sufficient for the article transport facility according to the present disclosure to achieve at least one of the above-described effects. [Explanation of symbols]

[0045] 1: Transport vehicle 2: Goods 3: Communication equipment 10: Communication unit 11: First physical layer device (physical layer device) 12: Communication control unit 13: Protocol stack 14: Upper control unit 20: Wireless communication device 30: Access point 31: First access point group 32: Second access point group 40: Communication Network 41: First network segment 42: Second network segment 50: Control device 51: First communication server 52: Second communication server 60: Travel route 100: Goods transport equipment

Claims

1. An article transport facility including a transport vehicle that travels along a specified travel route to transport an article, a control device that controls the transport vehicle, and a communication facility that connects the transport vehicle and the control device so that they can communicate with each other, the communication equipment includes a plurality of wireless communication access points installed so as to be able to communicate with the transport vehicle, and a communication network connecting the plurality of access points; an access point group configured by some of the plurality of access points is defined as a first access point group, and an access point group configured by a plurality of the access points different from the first access point group is defined as a second access point group; the communication network comprises a first network segment connecting the plurality of access points constituting the first access point group and a second network segment connecting the plurality of access points constituting the second access point group; the transport vehicle includes a wireless communication device and a communication unit that communicates with the access point selected from the plurality of access points via the wireless communication device; the communication unit comprises a physical layer device that controls connection with the wireless communication device, a communication control unit that processes data transmitted and received via the physical layer device and controls communication, a protocol stack that includes a communication protocol for communication via the communication network, and an upper control unit that controls the physical layer device, the communication control unit, and the protocol stack; The upper control unit performs a network segment switching process to restart the communication control unit and the protocol stack while maintaining the physical layer device in an activated state when switching from a state in which the transport vehicle is connected to an access point that constitutes the first access point group to a state in which the transport vehicle is connected to an access point that constitutes the second access point group, or when switching from a state in which the transport vehicle is connected to an access point that constitutes the second access point group to a state in which the transport vehicle is connected to an access point that constitutes the first access point group.

2. the control device includes a first communication server and a second communication server; the first network segment is configured to connect the first communication server and a plurality of the access points that make up the first access point group; The article transport facility according to claim 1 , wherein the second network segment is configured to connect the second communication server and a plurality of the access points that make up the second access point group.

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