Wireless communication system, transport carriage, and control method

Abstract

A transport carriage (4) has a first communication unit (24) and a second communication unit (28) that are disposed set apart from each other by a prescribed distance or more and are communicably connected to each other via a serial cable (34). The first communication unit (24) performs wireless communication with a communication device (8) using a prescribed channel. The second communication unit (28) shares, with the first communication unit (24) via the serial cable (34), information relating to wireless communication between the first communication unit (24) and the communication device (8). When a failure occurs in wireless communication between the first communication unit (24) and the communication device (8), the second communication unit (28) starts wireless communication with the communication device (8) using a prescribed channel.

Description

Wireless communication system, transport vehicle, and control method

[0001] The present invention relates to a wireless communication system, a transport vehicle, and a control method.

[0002] BACKGROUND ART A semiconductor manufacturing system is known that includes an overhead transport vehicle for transporting front opening unified pods (FOUPs) storing semiconductor wafers, and semiconductor manufacturing equipment for processing the semiconductor wafers.

[0003] The E84 communication sequence of SEMI (Semiconductor Equipment and Materials International) is applied to wireless communication between the transport vehicle and a communication device communicatively connected to a loading port of the semiconductor manufacturing equipment. When transferring a FOUP between the transport vehicle and the loading port, control signals are exchanged between the transport vehicle and the communication device according to the E84 communication sequence.

[0004] Incidentally, Patent Literature 1 discloses a wireless communication technology that includes a first wireless module that performs wireless communication on a first channel (frequency band) and a second wireless module that performs wireless communication on a second channel different from the first channel. In this wireless communication technology, data transmission is attempted using the first wireless module, and if the data transmission using the first wireless module fails, the technology switches to data transmission using the second wireless module.

[0005] Japanese Patent Application Laid-Open No. 2019-36816

[0006] When the wireless communication technology disclosed in Patent Document 1 is applied to the semiconductor manufacturing system described above and the first wireless module and the second wireless module are mounted on a transport vehicle, the following problem occurs: If data transmission from the first wireless module to the communication device fails, it takes time to change from the first channel to the second channel, which may delay the start of data transmission from the second wireless module to the communication device.

[0007] The present invention has been made in consideration of such problems, and its purpose is to provide a wireless communication system, a transport vehicle, and a control method that can quickly start wireless communication between one or more other communication units and a communication device when a failure occurs in wireless communication between a specific communication unit and a communication device.

[0008] In order to achieve the above-mentioned object, a wireless communication system according to a first aspect of the present invention is a wireless communication system comprising a transport vehicle that travels along a track and transports items, and a communication device that is communicatively connected to a transfer device to which the items are transferred between the transport vehicle and the transport vehicle, and that conducts wireless communication with the transport vehicle, wherein the transport vehicle has a plurality of communication units that are arranged at a distance from each other by a predetermined distance or more and are communicatively connected to each other via a communication cable, and a specific communication unit among the plurality of communication units conducts wireless communication with the communication device using a predetermined channel, and one or more other communication units among the plurality of communication units other than the specific communication unit share information regarding the wireless communication between the specific communication unit and the communication device with the specific communication unit via the communication cable, and when a failure occurs in the wireless communication between the specific communication unit and the communication device, the other one or more communication units start wireless communication with the communication device using the predetermined channel.

[0009] According to this aspect, information regarding wireless communication is shared among the multiple communication units, and the same predetermined channel is used for wireless communication between each of the multiple communication units and the communication device. As a result, even if a wireless communication failure occurs between a specific communication unit and the communication device, one or more other communication units can quickly start wireless communication with the communication device. Furthermore, the multiple communication units are arranged at least a predetermined distance from each other. As a result, even if a wireless communication failure occurs between a specific communication unit and the communication device due to a wireless communication path between the two being physically blocked by an obstacle or the like, the likelihood of successful wireless communication between the one or more other communication units and the communication device can be increased.

[0010] In addition, in the wireless communication system according to the second aspect of the present invention, in the first aspect, when a failure occurs in wireless communication between the specific communication unit and the communication device, the specific communication unit may be configured to hand over the wireless communication to one or more of the other communication units.

[0011] According to this aspect, even if a failure occurs during wireless communication between a specific communication unit and a communication device, one or more other communication units can take over the wireless communication between the specific communication unit and the communication device.

[0012] In addition, in a wireless communication system according to a third aspect of the present invention, in the first or second aspect, the information regarding the wireless communication may be configured to include wireless communication settings between the specific communication unit and the communication device.

[0013] According to this aspect, even if a failure occurs in wireless communication between a specific communication unit and a communication device, one or more other communication units can quickly start wireless communication with the communication device.

[0014] Furthermore, in a wireless communication system according to a fourth aspect of the present invention, in any one of the first to third aspects, the transporting cart may further have a control unit that controls the transporting cart, the specific communication unit may be wired to the control unit so as to be able to communicate with it, and may send and receive information between it and the control unit, and the other one or more communication units may be configured to send and receive information between them via the communication cable and the specific communication unit.

[0015] According to this aspect, the number of communication cables and I / O ports can be reduced compared to when each of the multiple communication units is directly connected to the control unit by wire. Also, the upper system can pretend that it is communicating with one of the multiple communication units of the transport vehicle.

[0016] In addition, in a wireless communication system according to a fifth aspect of the present invention, in any one of the first to fourth aspects, the communication cable may be a serial cable, and the one or more other communication units may be configured to share information regarding the wireless communication with the specific communication unit via serial communication using the serial cable.

[0017] According to this aspect, one or more other communication units can share information related to wireless communication with a specific communication unit through serial communication.

[0018] In addition, in a wireless communication system according to a sixth aspect of the present invention, in any one of the first to fifth aspects, the transport cart may further be configured to have a control unit that determines the specific communication unit from among the plurality of communication units that will communicate wirelessly with the communication device, depending on the location to which the item is to be transferred.

[0019] According to this aspect, depending on the location to which the item is to be transferred, a specific communication unit that is optimal for wireless communication with the communication device (e.g., the communication unit that is least likely to experience interference in wireless communication with the communication device) can be selected from among multiple communication units.

[0020] In addition, a seventh aspect of the present invention is a transport vehicle that runs along a track and transports items, and the transport vehicle has a plurality of communication units that are arranged at a distance greater than a predetermined distance from each other and are communicatively connected to each other via a communication cable, and a specific communication unit among the plurality of communication units uses a predetermined channel to communicate wirelessly with a communication device that is communicatively connected to a transfer device to which the items are transferred between the transport vehicle and the transport vehicle, and one or more other communication units among the plurality of communication units other than the specific communication unit share information regarding the wireless communication between the specific communication unit and the communication device with the specific communication unit via the communication cable, and when a failure occurs in the wireless communication between the specific communication unit and the communication device, the other one or more communication units start wireless communication with the communication device using the predetermined channel.

[0021] According to this aspect, information regarding wireless communication is shared among the multiple communication units, and the same predetermined channel is used for wireless communication between each of the multiple communication units and the communication device. As a result, even if a wireless communication failure occurs between a specific communication unit and the communication device, one or more other communication units can quickly start wireless communication with the communication device. Furthermore, the multiple communication units are arranged at least a predetermined distance from each other. As a result, even if a wireless communication failure occurs between a specific communication unit and the communication device due to a wireless communication path between the two being physically blocked by an obstacle or the like, the likelihood of successful wireless communication between the one or more other communication units and the communication device can be increased.

[0022] Furthermore, a control method according to an eighth aspect of the present invention is a control method for a wireless communication system comprising a mobile body that transports items and a communication device that is communicatively connected to a transfer device to which the items are transferred between the mobile body and that performs wireless communication with the mobile body, wherein the mobile body has a plurality of communication units that are arranged at a distance greater than a predetermined distance from each other and are communicatively connected to each other via a communication cable, and the control method includes the steps of: a specific communication unit among the plurality of communication units performing wireless communication with the communication device using a predetermined channel; one or more communication units among the plurality of communication units other than the specific communication unit sharing information regarding wireless communication between the specific communication unit and the communication device with the specific communication unit via the communication cable; and when a failure occurs in wireless communication between the specific communication unit and the communication device, the other one or more communication units starting wireless communication with the communication device using the predetermined channel.

[0023] According to this aspect, information regarding wireless communication is shared among the multiple communication units, and the same predetermined channel is used for wireless communication between each of the multiple communication units and the communication device. As a result, even if a wireless communication failure occurs between a specific communication unit and the communication device, one or more other communication units can quickly start wireless communication with the communication device. Furthermore, the multiple communication units are arranged at least a predetermined distance from each other. As a result, even if a wireless communication failure occurs between a specific communication unit and the communication device due to a wireless communication path between the two being physically blocked by an obstacle or the like, the likelihood of successful wireless communication between the one or more other communication units and the communication device can be increased.

[0024] The present invention can be realized not only as an apparatus, but also as a method in which the processing means constituting the apparatus are steps, as a program that causes a computer to execute those steps, as a computer-readable recording medium such as a CD-ROM on which the program is recorded, or as information, data, or signals that represent the program.These programs, information, data, and signals may be distributed via a communication network such as the Internet.

[0025] According to a wireless communication system, etc. relating to one aspect of the present invention, when a failure occurs in wireless communication between a specific communication unit and a communication device, wireless communication between one or more other communication units and the communication device can be started early.

[0026] 1 is a diagram illustrating an overview of a wireless communication system according to an embodiment. FIG. 2 is a schematic diagram for explaining transfer of a FOUP in the wireless communication system according to an embodiment. FIG. 3 is a schematic diagram for explaining the positional relationship between a control unit, a first communication unit, and a second communication unit in a transport platform according to an embodiment. FIG. 4 is a block diagram illustrating the functional configuration of a wireless communication system according to an embodiment. FIG. 5 is a sequence diagram illustrating the flow of operation of the wireless communication system according to an embodiment when no failure occurs in wireless communication between a first communication unit and a communication device. FIG. 6 is a sequence diagram illustrating the flow of operation of the wireless communication system according to an embodiment when a failure occurs in wireless communication between the first communication unit and the communication device. FIG. 7 is a sequence diagram illustrating the flow of operation of the wireless communication system according to an embodiment when a failure occurs in wireless communication between the first communication unit and the communication device, and in wireless communication between the second communication unit and the communication device.

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection forms, steps, step order, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0028] (Embodiments) [1. Overview of Wireless Communication System] First, an overview of a wireless communication system 2 according to an embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a diagram showing an overview of the wireless communication system 2 according to an embodiment. Fig. 2 is a schematic diagram for explaining the transfer of a FOUP 10 in the wireless communication system 2 according to an embodiment. Fig. 3 is a schematic diagram for explaining the positional relationship between a control unit 22, a first communication unit 24, and a second communication unit 28 in a transporting platform 4 according to an embodiment.

[0029] 1, the wireless communication system 2 is a system established in, for example, a semiconductor manufacturing factory. The wireless communication system 2 includes a transport vehicle 4 (an example of a moving object), a semiconductor manufacturing apparatus 6, and a communication device 8.

[0030] The transport vehicle 4 is an overhead traveling transport vehicle, known as an OHT (Overhead Hoist Transfer), for transporting FOUPs 10 (an example of an article) storing semiconductor wafers. The transport vehicle 4 travels unmanned along a track 12 installed on the ceiling of the semiconductor manufacturing factory. Although a plurality of transport vehicles 4 (e.g., several hundred vehicles) are arranged in the semiconductor manufacturing factory, for the sake of convenience of explanation, only one transport vehicle 4 is shown in FIG. 1.

[0031] The transport vehicle 4 has a vehicle body 14 , a gripping unit 16 , a lifting mechanism 18 , and a lateral mechanism 20 .

[0032] The carriage body 14 is configured to be hollow and have a substantially rectangular shape when viewed in the XY plane, and travels along the track 12. The carriage body 14 is capable of storing a FOUP 10 inside.

[0033] The gripper 16 is mounted inside the carriage body 14. The gripper 16 holds the FOUP 10 by gripping the upper end of the FOUP 10, thereby suspending and holding the FOUP 10.

[0034] The lifting mechanism 18 is mounted inside the carriage body 14. The lifting mechanism 18 is a mechanism for raising and lowering the gripping part 16 in the vertical direction (Z-axis direction), and is made of, for example, metal.

[0035] The lateral mechanism 20 is mounted inside the carriage body 14. The lateral mechanism 20 is a mechanism for moving the gripping unit 16 and the lifting mechanism 18 in the horizontal direction (Y-axis direction), and is made of, for example, metal. The lateral mechanism 20 is slidable between a storage position (not shown) in which it is stored inside the carriage body 14, and a protruding position (see FIG. 2) in which it protrudes laterally from the carriage body 14. When the lateral mechanism 20 is in the storage position, the gripping unit 16 and the lifting mechanism 18 are located inside the carriage body 14. On the other hand, when the lateral mechanism 20 is in the protruding position, the gripping unit 16 and the lifting mechanism 18 are located outside the carriage body 14.

[0036] For example, when transferring a FOUP 10 between the transport platform 4 and a loading port 38 (described later) of the semiconductor manufacturing equipment 6, the transport platform 4 first stops at a position directly above the loading port 38. In this state, the lateral mechanism 20 slides from the storage position to the protruding position, and then the lifting mechanism 18 lowers the gripper 16 from the transport platform 4 to the vicinity of the loading port 38, and transfers the FOUP 10 between the gripper 16 and the loading port 38. Specifically, the FOUP 10 placed on the loading port 38 is grasped by the gripper 16, or the FOUP 10 is unloaded from the gripper 16 to the loading port 38. Thereafter, when the transfer of the FOUP 10 is completed, the lifting mechanism 18 raises the gripper 16 from the vicinity of the loading port 38 to the transport platform 4, and then the lateral mechanism 20 slides from the protruding position to the storage position.

[0037] As shown in Figures 2 and 3, the transport vehicle 4 further has a control unit 22, a first communication unit 24 (an example of a specific communication unit), a first antenna 26, a second communication unit 28 (an example of one or more other communication units), and a second antenna 30.

[0038] The control unit 22 is mounted inside the carriage body 14 and controls the overall operation of each part of the transport carriage 4 .

[0039] The first communication unit 24 is communicatively connected (wired) to the control unit 22 via a serial cable 32. As a result, the first communication unit 24 transmits and receives information to and from the control unit 22 by serial communication using the serial cable 32, for example, a communication method such as RS-232C. The first communication unit 24 also transmits and receives information to and from the communication device 8 by wireless communication using a predetermined channel (frequency band). The first communication unit 24 transmits and receives information to and from the communication device 8 by short-range wireless communication. The short-range wireless communication is, for example, wireless communication using BLE (Bluetooth (registered trademark) Low Energy) or the like.

[0040] The first antenna 26 is an antenna for the first communication unit 24, and is communicatively connected to the first communication unit 24 via a cable (not shown).

[0041] The second communication unit 28 is communicatively connected to the first communication unit 24 via a serial cable 34 (an example of a communication cable). As a result, the second communication unit 28 transmits and receives information to and from the first communication unit 24 via serial communication using the serial cable 34, for example, a communication method such as RS-232C. The second communication unit 28 also transmits and receives information regarding the wireless communication between the first communication unit 24 and the communication device 8 via the serial cable 34. That is, the first communication unit 24 and the second communication unit 28 share information regarding the wireless communication between them and the communication device 8. The second communication unit 28 also transmits and receives information via wireless communication with the communication device 8 using the above-mentioned predetermined channel. That is, the first communication unit 24 and the second communication unit 28 perform wireless communication with the communication device 8 using the same predetermined channel. The first communication unit 24 and the second communication unit 28 also transmit and receive information with the communication device 8 via short-range wireless communication. As shown in FIG. 3, the first communication unit 24 and the second communication unit 28 are arranged at least a predetermined distance from each other.

[0042] The second antenna 30 is an antenna for the second communication unit 28, and is communicatively connected to the second communication unit 28 via a cable (not shown). As shown in Fig. 3, the first antenna 26 and the second antenna 30 are disposed diagonally on the bogie body 14, for example, when viewed in the XY plane.

[0043] The semiconductor manufacturing equipment 6 is an apparatus for processing or temporarily storing semiconductor wafers stored in the FOUP 10, and is installed directly below the track 12. The semiconductor manufacturing equipment 6 has a loading / unloading opening 36 for loading and unloading the FOUP 10, and a loading port 38 (an example of a transfer device) located near the loading / unloading opening 36. The loading port 38 is a load port for loading the FOUP 10. The loading port 38 transfers the FOUP 10 between the gripper 16 of the transport vehicle 4 and the semiconductor manufacturing equipment 6, and delivers the FOUP 10 to and from the semiconductor manufacturing equipment 6 through the loading / unloading opening 36.

[0044] Although a semiconductor manufacturing factory is equipped with a plurality of (e.g., several thousand) semiconductor manufacturing apparatuses 6, for convenience of explanation, only one semiconductor manufacturing apparatus 6 is shown in Fig. 1. Furthermore, in the present embodiment, the semiconductor manufacturing apparatus 6 has one loading port 38, but the present invention is not limited to this, and the semiconductor manufacturing apparatus 6 may have a plurality of loading ports 38.

[0045] The communication device 8 is a communication device that mediates communication between the transport cart 4 and the load port 38 of the semiconductor manufacturing equipment 6. The communication device 8 is disposed, for example, on the top surface of the semiconductor manufacturing equipment 6, and is communicatively connected to the load port 38 of the semiconductor manufacturing equipment 6 via a parallel cable 40. This allows the communication device 8 to send and receive information to and from the load port 38 of the semiconductor manufacturing equipment 6. The SEMI E84 communication sequence is applied to communication between the communication device 8 and the transport cart 4. Note that although the same number of communication devices 8 as the load ports 38 are installed in a semiconductor manufacturing factory, for convenience of explanation, only one communication device 8 is shown in FIG. 1.

[0046] In the wireless communication system 2 described above, when the transport vehicle 4 grasps the FOUP 10 placed on the loading port 38, or when the FOUP 10 is unloaded from the transport vehicle 4 to the loading port 38, a control signal (information) is exchanged between the first communication unit 24 (or the second communication unit 28) of the transport vehicle 4 and the communication device 8 by the E84 communication sequence. The E84 communication sequence employs an interlock sequence consisting of multiple steps, such that when the FOUP 10 is transferred between the transport vehicle 4 and the loading port 38, the process does not proceed to the next step unless a specific control signal is turned off.

[0047] 2. Functional Configuration of Wireless Communication System The functional configuration of the wireless communication system 2 according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a block diagram showing the functional configuration of the wireless communication system 2 according to the embodiment.

[0048] As shown in FIG. 4, the transport vehicle 4 has a control unit 22, a first communication unit 24, and a second communication unit 28.

[0049] The control unit 22 executes various processes by controlling the first communication unit 24. For example, when the transport vehicle 4 arrives at a position directly above the loading port 38 to which the FOUP 10 (see FIG. 1 ) is to be transferred, the control unit 22 instructs the first communication unit 24 to start wireless communication with the communication device 8. Note that the control unit 22 is realized, for example, by a processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0050] The first communication unit 24 transmits and receives information to and from the control unit 22 via a serial cable 32 (see FIG. 3 ). The first communication unit 24 also transmits and receives information to and from the communication device 8 via wireless communication using the predetermined channel. Furthermore, when a failure occurs in the wireless communication between the first communication unit 24 and the communication device 8, the first communication unit 24 terminates the wireless communication with the communication device 8 and instructs the second communication unit 28 to start the wireless communication with the communication device 8.

[0051] The second communication unit 28 transmits and receives information to and from the first communication unit 24 via a serial cable 34 (see FIG. 3 ). The second communication unit 28 also transmits and receives information to and from the control unit 22 via the serial cable 34, the first communication unit 24, and the serial cable 32. If a failure occurs in wireless communication between the first communication unit 24 and the communication device 8, the second communication unit 28 starts wireless communication with the communication device 8 using the predetermined channel based on an instruction from the first communication unit 24. In other words, while one of the first communication unit 24 and the second communication unit 28 is performing wireless communication with the communication device 8, the other one does not perform wireless communication with the communication device 8.

[0052] The loading port 38 of the semiconductor manufacturing equipment 6 has a communication unit 42 and a control unit 44 .

[0053] The communication unit 42 transmits and receives information to and from the communication device 8 via the parallel cable 40 (see FIG. 1).

[0054] The control unit 44 executes various processes by controlling the communication unit 42. Specifically, the control unit 44 executes an interlock process using an E84 communication sequence for transferring the FOUP 10 to and from the transport vehicle 4. The control unit 44 also executes a process for transferring the FOUP 10 to and from the semiconductor manufacturing equipment 6 through the loading / unloading port 36 (see FIG. 1 ). The control unit 44 is realized, for example, by a processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0055] The communication device 8 includes a communication unit 46 and a control unit 48 .

[0056] The communication unit 46 transmits and receives information to and from the placement port 38 via the parallel cable 40. The communication unit 46 also transmits and receives information to and from the transporting platform 4 via wireless communication.

[0057] The control unit 48 executes various processes by controlling the communication unit 46. The control unit 48 is realized, for example, by a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

[0058] 5, a description will be given of the operation of the wireless communication system 2 when no failure occurs in wireless communication between the first communication unit 24 and the communication device 8. Fig. 5 is a sequence diagram showing the flow of operation of the wireless communication system 2 according to the embodiment when no failure occurs in wireless communication between the first communication unit 24 and the communication device 8.

[0059] 5 , when the transporting vehicle 4 arrives at a position directly above the loading port 38, the control unit 22 of the transporting vehicle 4 transmits information regarding wireless communication settings between the first communication unit 24 and the communication device 8 (an example of information regarding wireless communication between the first communication unit 24 and the communication device 8) to the first communication unit 24 via the serial cable 32 (S101). As a result, the first communication unit 24 receives the information regarding wireless communication settings from the control unit 22 of the transporting vehicle 4. The information regarding wireless communication settings includes, for example, (a) an address (a unique identifier such as an ID) of the communication device 8 to be connected, (b) a channel to be used for wireless communication, and (c) a transmission output value. At this time, as described above, the second communication unit 28 shares the information regarding wireless communication settings with the first communication unit 24 via the serial cable 34. The control unit 22 of the transporting vehicle 4 may transmit data to be transmitted to the communication device 8 (e.g., a control signal used in the E84 communication sequence) together with the information regarding wireless communication settings to the first communication unit 24.

[0060] Next, the control unit 22 of the transporting vehicle 4 instructs the first communication unit 24 to start wireless communication with the communication device 8 (S102).

[0061] Next, the first communication unit 24 of the transporting vehicle 4 transmits information for establishing wireless communication with the communication device 8 to the communication device 8 based on an instruction from the control unit 22 (S103).

[0062] At this time, since no interference has occurred in the wireless communication between the first communication unit 24 and the communication device 8, the communication device 8 can receive information from the first communication unit 24 of the transporting vehicle 4. Next, the communication device 8 transmits a response to the information to the first communication unit 24 (S104).

[0063] This establishes wireless communication between the first communication unit 24 and the communication device 8, and the first communication unit 24 executes communication with the communication device 8 for interlock processing according to the E84 communication sequence (S105).

[0064] Next, the operation of the wireless communication system 2 when a failure occurs in wireless communication between the first communication unit 24 and the communication device 8 will be described with reference to Fig. 6. Fig. 6 is a sequence diagram showing the flow of operation of the wireless communication system 2 according to the embodiment when a failure occurs in wireless communication between the first communication unit 24 and the communication device 8.

[0065] In the case shown in FIG. 6, it is assumed that no failure occurs in the wireless communication between the second communication unit 28 and the communication device 8.

[0066] As shown in FIG. 6, when the transport vehicle 4 arrives at a position directly above the loading port 38, steps S201 and S202 are executed in the same manner as steps S101 and S102 in the sequence diagram shown in FIG.

[0067] After step S202, the first communication unit 24 of the transporting vehicle 4 transmits information for establishing wireless communication with the communication device 8 to the communication device 8 based on an instruction from the control unit 22 (S203). At this time, since a failure has occurred in the wireless communication between the first communication unit 24 and the communication device 8, the communication device 8 cannot receive information from the first communication unit 24 of the transporting vehicle 4.

[0068] In addition, possible causes of interference with wireless communication between the first communication unit 24 and the communication device 8 include, for example, the lateral mechanism 20 sliding from the storage position to the protruding position physically blocking the wireless communication path between the first communication unit 24 and the communication device 8.

[0069] Next, the first communication unit 24 of the transporting vehicle 4 retries transmitting information to the communication device 8 multiple times until a response is received from the communication device 8 (S204, S205).

[0070] If the communication device 8 is fortunate enough to receive information from the first communication unit 24 of the transport vehicle 4, it will transmit a response to the information to the first communication unit 24. However, even in this case, due to a failure in wireless communication between the first communication unit 24 and the communication device 8, the radio wave intensity of the response from the communication device 8 may be extremely low (for example, −80 dBm or less), and the first communication unit 24 will ignore the response from the communication device 8.

[0071] If the first communication unit 24 of the transport cart 4 does not receive a response from the communication device 8 even after a predetermined time has passed since the first transmission of information to the communication device 8 (i.e., if a wireless communication timeout occurs), the first communication unit 24 of the transport cart 4 stops wireless communication with the communication device 8 (S206).

[0072] Next, the first communication unit 24 of the transport vehicle 4 instructs the second communication unit 28 to start wireless communication with the communication device 8 (S207). At this time, the first communication unit 24 transmits information regarding wireless communication settings to the second communication unit 28 via the serial cable 34. Here, the content of the instruction from the first communication unit 24 to the second communication unit 28 to start wireless communication may include information regarding the most recent wireless communication that the first communication unit 24 performed with the communication device 8. This information may be, for example, transmitted information (e.g., a sequence number indicated in a packet) regarding the communication data that was performed immediately before. Based on the instruction from the first communication unit 24, the second communication unit 28 transmits information for establishing wireless communication with the communication device 8 to the communication device 8 (S208).

[0073] At this time, since no interference has occurred in the wireless communication between the second communication unit 28 and the communication device 8, the communication device 8 can receive information from the second communication unit 28 of the transporting vehicle 4. Next, the communication device 8 transmits a response to the information to the second communication unit 28 (S209).

[0074] This establishes wireless communication between the second communication unit 28 and the communication device 8, and the second communication unit 28 transmits information indicating this to the first communication unit 24 (S210), and executes communication with the communication device 8 for interlock processing using the E84 communication sequence (S211).

[0075] If a failure occurs during wireless communication between the first communication unit 24 and the communication device 8, the first communication unit 24 may hand over the wireless communication to the second communication unit 28. This allows the second communication unit 28 to take over wireless communication with the communication device 8.

[0076] Next, with reference to Fig. 7, an operation of the wireless communication system 2 when a failure occurs in the wireless communication between the first communication unit 24 and the communication device 8 and in the wireless communication between the second communication unit 28 and the communication device 8 will be described. Fig. 7 is a sequence diagram showing the flow of operation of the wireless communication system 2 according to the embodiment when a failure occurs in the wireless communication between the first communication unit 24 and the communication device 8 and in the wireless communication between the second communication unit 28 and the communication device 8.

[0077] In the case shown in FIG. 7, it is assumed that after a failure occurs in wireless communication between the first communication unit 24 and the communication device 8, the failure in wireless communication is resolved.

[0078] As shown in FIG. 7, when the transport vehicle 4 arrives at a position directly above the loading port 38, steps S301 and S302 are executed in the same manner as steps S101 and S201 in the sequence diagram shown in FIG.

[0079] After step S302, the first communication unit 24 of the transporting vehicle 4 transmits information for establishing wireless communication with the communication device 8 to the communication device 8 based on an instruction from the control unit 22 (S303). At this time, since a failure has occurred in the wireless communication between the first communication unit 24 and the communication device 8, the communication device 8 cannot receive information from the first communication unit 24 of the transporting vehicle 4.

[0080] Next, the first communication unit 24 of the transporting vehicle 4 retries transmitting information to the communication device 8 multiple times until a response is received from the communication device 8 (S304, S305).

[0081] If the communication device 8 is fortunate enough to receive information from the first communication unit 24 of the transport vehicle 4, it will transmit a response to the information to the first communication unit 24. However, even in this case, the first communication unit 24 will ignore the response from the communication device 8 because, for example, the radio wave intensity of the response from the communication device 8 is extremely low due to a failure in wireless communication between the first communication unit 24 and the communication device 8.

[0082] If the first communication unit 24 of the transport cart 4 does not receive a response from the communication device 8 even after a predetermined time has elapsed since the first transmission of information to the communication device 8, it stops wireless communication with the communication device 8 (S306).

[0083] Next, the first communication unit 24 of the transporting vehicle 4 instructs the second communication unit 28 to start wireless communication with the communication device 8 (S307). At this time, the first communication unit 24 transmits information about wireless communication settings to the second communication unit 28 via the serial cable 34.

[0084] Next, the second communication unit 28 of the transporting vehicle 4 transmits information for establishing wireless communication with the communication device 8 to the communication device 8 based on the instruction from the first communication unit 24 (S308). At this time, since a failure has occurred in the wireless communication between the second communication unit 28 and the communication device 8, the communication device 8 cannot receive information from the second communication unit 28 of the transporting vehicle 4.

[0085] Next, the second communication unit 28 of the transporting vehicle 4 retries transmitting information to the communication device 8 multiple times until a response is received from the communication device 8 (S309, S310).

[0086] If no response is received from the communication device 8 even after a predetermined time has elapsed since the second communication unit 28 first transmitted information to the communication device 8, the first communication unit 24 of the transporting vehicle 4 instructs the second communication unit 28 to terminate wireless communication with the communication device 8 (S311). Here, when the second communication unit 28 receives the instruction to terminate the wireless communication, it may respond to the first communication unit 24 with information regarding the immediately preceding wireless communication that was carried out with the communication device 8.

[0087] Next, the first communication unit 24 of the transporting carriage 4 resumes wireless communication with the communication device 8 (S312) and transmits information for establishing wireless communication with the communication device 8 to the communication device 8 based on an instruction from the control unit 22 (S313). At this time, if the wireless communication failure between the first communication unit 24 and the communication device 8 has been resolved, the communication device 8 can receive information from the first communication unit 24.

[0088] Next, the communication device 8 transmits a response to the information to the first communication unit 24 (S314).

[0089] This establishes wireless communication between the first communication unit 24 and the communication device 8, and the first communication unit 24 executes communication with the communication device 8 for interlock processing according to the E84 communication sequence (S315).

[0090] [4. Effects] In the present embodiment, as described above, information related to wireless communication is shared between the first communication unit 24 and the second communication unit 28, and the same predetermined channel is used for wireless communication between each of the first communication unit 24 and the second communication unit 28 and the communication device 8. This allows the second communication unit 28 to start wireless communication with the communication device 8 early, even if a failure occurs in wireless communication between the first communication unit 24 and the communication device 8.

[0091] Furthermore, the first communication unit 24 and the second communication unit 28 are arranged at a predetermined distance or more from each other. As a result, if a wireless communication failure occurs between the first communication unit 24 and the communication device 8 due to a physical blockage of the wireless communication path between the two due to an obstacle or the like, the second communication unit 28 can be used to increase the possibility of successful wireless communication with the communication device 8.

[0092] (Other Modifications, etc.) While the wireless communication system of the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment. The present invention also includes modifications that can be made to the above embodiment by those skilled in the art, and other modifications that can be realized by arbitrarily combining the components of the above embodiment.

[0093] In the above embodiment, when the transporting vehicle 4 arrives at a position directly above the loading port 38, the control unit 22 of the transporting vehicle 4 instructs the first communication unit 24 to start wireless communication with the communication device 8, but this is not limiting. The control unit 22 of the transporting vehicle 4 may use the second communication unit 28 as a main unit and instruct the second communication unit 28 to start wireless communication with the communication device 8. In this case, the control unit 22 transmits information regarding wireless communication settings between the second communication unit 28 and the communication device 8 to the second communication unit 28 via the serial cable 32, the first communication unit 24, and the serial cable 34.

[0094] Alternatively, the control unit 22 may determine either the first communication unit 24 or the second communication unit 28 as the communication unit that will first communicate wirelessly with the communication device 8, depending on the location to which the FOUP 10 is transferred.

[0095] In addition, in the above embodiment, the transport vehicle 4 has two communication units (first communication unit 24 and second communication unit 28), but this is not limited to this and the transport vehicle 4 may have three or more communication units.

[0096] In the above embodiment, the control unit 22 and the first communication unit 24 are connected by wire, and the first communication unit 24 and the second communication unit 28 are connected by wire, but this is not limiting. For example, each of the first communication unit 24 and the second communication unit 28 may be directly connected by wire to the control unit 22.

[0097] Furthermore, in the above embodiment, the moving body is applied to a transporting platform, but the present invention is not limited to this, and the moving body may be applied to, for example, an unmanned transport vehicle that travels on the ground.

[0098] In the above-described embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0099] The wireless communication system according to the present invention can be applied to, for example, a semiconductor manufacturing system for transporting FOUPs by a transport cart that travels along a track installed on the ceiling.

[0100] 2 Wireless communication system 4 Transport vehicle 6 Semiconductor manufacturing equipment 8 Communication device 10 FOUP 12 Track 14 Vehicle body 16 Grip unit 18 Lifting mechanism 20 Lateral mechanism 22, 44, 48 Control unit 24 First communication unit 26 First antenna 28 Second communication unit 30 Second antenna 32, 34 Serial cable 36 Loading / unloading port 38 Placement port 40 Parallel cable 42, 46 Communication unit

Claims

1. A wireless communication system comprising a transport cart that travels along a track and transports articles, and a communication device that is communicatively connected to a transfer device to which the articles are transferred between the transport cart and that performs wireless communication with the transport cart, wherein the transport cart has a plurality of communication units that are arranged at a distance or more from each other and are communicatively connected to each other via a communication cable, a specific communication unit of the multiple communication units wirelessly communicates with the communication device using a specific channel, and one or more other communication units of the multiple communication units other than the specific communication unit share information regarding the wireless communication between the specific communication unit and the communication device with the specific communication unit via the communication cable, and when a failure occurs in the wireless communication between the specific communication unit and the communication device, the other one or more communication units start wireless communication with the communication device using the specific channel.

2. The wireless communication system according to claim 1, wherein, when a failure occurs in wireless communication between the specific communication unit and the communication device, the specific communication unit hands over the wireless communication to the one or more other communication units.

3. The wireless communication system according to claim 1, wherein the information regarding wireless communication includes wireless communication settings between the specific communication unit and the communication device.

4. The wireless communication system described in claim 1, wherein the transport vehicle further has a control unit that controls the transport vehicle, the specific communication unit is communicatively connected by wire to the control unit and transmits and receives information between the control unit, and the one or more other communication units transmit and receive information between the control unit via the communication cable and the specific communication unit.

5. A wireless communication system according to any one of claims 1 to 4, wherein the communication cable is a serial cable, and the one or more other communication units share information regarding the wireless communication with the specific communication unit through serial communication using the serial cable.

6. The wireless communication system according to claim 1, wherein the transport cart further has a control unit which determines, depending on the location to which the item is to be transferred, the specific communication unit from among the plurality of communication units that will wirelessly communicate with the communication device.

7. A transport cart which travels along a track and transports articles, the transport cart having a plurality of communication units arranged at least a predetermined distance from each other and communicatively connected to each other via a communication cable, a specific communication unit among the plurality of communication units using a predetermined channel to wirelessly communicate with a communication device communicatively connected to a transfer apparatus to which the articles are transferred between the transport cart, one or more communication units other than the specific communication unit among the plurality of communication units share information regarding the wireless communication between the specific communication unit and the communication device with the specific communication unit via the communication cable, and when a failure occurs in the wireless communication between the specific communication unit and the communication device, the other one or more communication units start wireless communication with the communication device using the predetermined channel.

8. A control method for a wireless communication system including a mobile body that transports articles, and a communication device that is communicatively connected to a transfer device to which the articles are transferred between the mobile body and that performs wireless communication with the mobile body, wherein the mobile body has a plurality of communication units that are arranged at a distance from each other by a predetermined distance or more and are communicatively connected to each other via a communication cable, the control method including the steps of: a specific communication unit among the plurality of communication units wirelessly performing communication with the communication device using a predetermined channel; one or more communication units among the plurality of communication units other than the specific communication unit sharing information regarding wireless communication between the specific communication unit and the communication device with the specific communication unit via the communication cable; and when a failure occurs in wireless communication between the specific communication unit and the communication device, the other one or more communication units starting wireless communication with the communication device using the predetermined channel.

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