WIRELESS COMMUNICATION SYSTEM, TRANSPORT VEHICLE AND CONTROL METHOD

Abstract

A transport vehicle (4) has a first communication unit (24) and a second communication unit (28), which are arranged at a predetermined distance from each other and connected to each other via a communication cable (34). The first communication unit (24) conducts wireless communication with a communication device (8) using a predetermined channel. The second communication unit (28) shares information with the first communication unit (24) via the communication cable (34), the information being information relating to the wireless communication between the first communication unit (24) and the communication device (8).If an error occurs in the wireless communication between the first communication unit (24) and the communication device (8), the second communication unit (28) initiates wireless communication with the communication device (8) using the specified channel.

Description

[Technical field]

[0001] The present invention relates to wireless communication systems, transport vehicles and control methods. [Technical background]

[0002] Semiconductor manufacturing systems are known which include: overhead transport vehicles for transporting Front Opening Unified Pods (FOUPs) containing semiconductor wafers, and semiconductor manufacturing equipment for processing the semiconductor wafers (see, for example, patent literature (PTL) 1).

[0003] The E84 communication sequence from Semiconductor Equipment and Materials International (SEMI) is used for wireless communication between a transport vehicle and a communication device connected to the loading port of a semiconductor device. When a FOUP (Factory Open Up) is transmitted between the transport vehicle and the loading port, control signals are exchanged between the transport vehicle and the communication device via the E84 communication sequence.

[0004] PTL 1 discloses a wireless communication technology comprising a first wireless module that performs wireless communication using a first channel (frequency band), and a second wireless module that performs wireless communication using a second channel that differs from the first channel. In this wireless communication technology, if data transmission using the first wireless module is attempted and fails, data transmission is switched to using the second wireless module. [Citation list][Patent literature]

[0005] [PTL 1] Japanese unexamined patent application no. 2019-36816 [Description of the invention][Technical problem]

[0006] When the wireless communication technology disclosed in PTL 1 is applied to the semiconductor manufacturing system described above, and the first and second wireless modules are mounted on the transport vehicle, the following problem occurs. If data transmission from the first wireless module to the communication device fails, the start of data transmission from the second wireless module to the communication device could be delayed because switching from the first channel to the second channel takes time.

[0007] The present invention was conceived in light of this problem and aims to provide a wireless communication system, a transport vehicle and a control method that enable an early start of wireless communication between one or more other communication units and a communication device when a fault occurs in the wireless communication between a particular communication unit and the communication device. [Solution to the problem]

[0008] To achieve the above-described goal, a wireless communication system according to a first aspect of the present invention comprises: a transport vehicle moving along a track and carrying an object; and a communication device connected to a transfer device that transfers the object to and from the transport vehicle and performs wireless communication with the transport vehicle. The transport vehicle has several communication units arranged at a predetermined distance from one another and connected to each other via a communication cable. A specific communication unit from among the several communication units performs wireless communication with the communication device using a predetermined channel.One or more other communication units, excluding the specified communication unit, exchange information with the specified communication unit via the communication cable. This information pertains to the wireless communication between the specified communication unit and the communication device. If a fault occurs in the wireless communication between the specified communication unit and the communication device, the one or more other communication units initiate wireless communication with the communication device using the designated channel.

[0009] According to this aspect, information regarding wireless communication is exchanged between the multiple communication units, and the same predefined channel is used for wireless communication between each of the multiple communication units and the communication device. This allows one or more other communication units to immediately establish wireless communication with the communication device, even if a fault occurs in the wireless communication between a particular communication unit and the communication device. The multiple communication units are arranged at a predefined distance from each other.This can increase the probability of success for wireless communication between one or more other communication units and the communication device, for example, if a failure in wireless communication between the specific communication unit and the communication device occurs due to a physical blockage by obstacles in the wireless communication path between the specific communication unit and the communication device.

[0010] In a wireless communication system according to a second aspect of the present invention, in the first aspect of the present invention, if an error occurs in the wireless communication between the specific communication unit and the communication device, the specific communication unit could transfer the wireless communication to one or more other communication units.

[0011] According to the present aspect, even if an error occurs during wireless communication between the specific communication unit and the 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 a wireless communication system according to a third aspect of the present invention, the information relating to wireless communication in the first or second aspect of the present invention could include wireless communication settings between the specific communication unit and the communication device.

[0013] According to the present aspect, even if an error occurs in the wireless communication between the specific communication unit and the communication device, one or more other communication units can immediately establish wireless communication with the communication device.

[0014] In a wireless communication system according to a fourth aspect of the present invention, the transport vehicle could further comprise a control device that controls the transport vehicle, as specified in any one of the first to third aspects of the present invention. The communication unit could be connected to and able to communicate with the control device, transmitting and receiving information to and from the control device. One or more other communication units could transmit and receive information to and from the control device via the communication cable and the communication unit.

[0015] Based on this aspect, the number of communication cables and I / O ports can be reduced compared to cases where each of the multiple communication units is directly wired and connected to the control unit. It is also possible to design the system as if the upper system communicates with one of the multiple communication units that the transport vehicle has.

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

[0017] According to the present aspect, one or more other communication units can exchange information with the specific communication unit via serial communication using wireless communication.

[0018] In a wireless communication system according to a sixth aspect of the present invention, the transport vehicle could further comprise a control device which, according to a location to which the object is to be transported, determines the specific communication unit which performs the wireless communication with the communication device, wherein the specific communication unit is determined from several communication units.

[0019] According to the present aspect, it is possible, depending on the location to which an object is to be transported, to determine from among the several communication units a specific communication unit that is optimal as the communication unit that carries out the wireless communication with the communication device (e.g. the one where the probability of a failure of the wireless communication with the communication device is lowest).

[0020] A transport vehicle according to a seventh aspect of the present invention travels along a rail and transports an object. The transport vehicle has several communication units arranged at a predetermined distance from one another and connected to each other via a communication cable. A specific communication unit among the several communication units performs wireless communication with a communication device using a predetermined channel, the communication device being connected to a transmission device that transmits the object to and from the transport vehicle.One or more other communication units, excluding the specified communication unit among the multiple communication units, exchange information with the specified communication unit via the communication cable, the information being information regarding the wireless communication between the specified communication unit and the communication device. If a fault occurs in the wireless communication between the specified communication unit and the communication device, one or more other communication units begin wireless communication with the communication device using the designated channel.

[0021] According to this aspect, information regarding wireless communication is exchanged between the multiple communication units, and the same predefined channel is used for wireless communication between each of the multiple communication units and the communication device. This allows one or more other communication units to immediately establish wireless communication with the communication device, even if a failure occurs in the wireless communication between a specific communication unit and the communication device. The multiple communication units are arranged at a predefined distance from each other.This can increase the probability of successful wireless communication between one or more other communication units and the communication device, for example, if a failure in wireless communication between the specific communication unit and the communication device occurs due to a physical blockage caused by obstacles in the wireless communication path between the specific communication unit and the communication device.

[0022] A control method according to an eighth aspect of the present invention is a control method in a wireless communication system comprising: a movable body that transports an object; and a communication device that is in communication connection with a transmission device that transmits the object to and from the movable body and performs wireless communication with the movable body. The movable body has several communication units that are arranged at a predetermined distance from one another and are connected to each other via a communication cable.The control method includes: conducting wireless communication with the communication device using a predetermined channel and a specific communication unit; sharing information regarding the wireless communication between the specific communication unit and the communication device by one or more other communication units with the specific communication unit via the communication cable, wherein the one or more other communication units exclude the specific communication unit from the multiple communication units; and. initiating wireless communication with the communication device using the specified channel by one or more other communication units when an error occurs in the wireless communication between the specified communication unit and the communication device.

[0023] According to this aspect, information regarding wireless communication is exchanged between multiple communication units, and the same predefined channel is used for wireless communication between these units and the communication device. This allows one or more other communication units to immediately initiate wireless communication with the communication device, even if a fault occurs in the wireless communication between a particular communication unit and the device. The multiple communication units are arranged at a predetermined distance from each other.This can increase the probability of success for wireless communication between one or more other communication units and the communication device, for example, if a failure in wireless communication between the specific communication unit and the communication device occurs due to a physical blockage by obstacles in the wireless communication path between the specific communication unit and the communication device.

[0024] It should be noted that the present invention can be implemented not only as a device but also as a method comprising, as steps, processes that are carried out by means contained in the device, as a program that causes a computer to execute these 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 specify the program. The program, information, data, and signals could be disseminated via a communication network such as the Internet. [Advantageous effects of the invention]

[0025] The wireless communication system according to a first aspect of the present invention enables the early commencement of wireless communication between one or more other communication units and a communication device when an error occurs in the wireless communication between a particular communication unit and the communication device. [Brief description of the drawings] [ Fig. 1] Fig. Figure 1 is a diagram illustrating the structure of a wireless communication system according to one embodiment. [ Fig. 2] Fig. Figure 2 is a schematic diagram to illustrate the transmission of FOUP in the wireless communication system according to the embodiment. [ Fig. 3] Fig. Figure 3 is a schematic diagram to illustrate the positional relationship between a control device, a first communication unit and a second communication unit in a transport vehicle according to the embodiment. [ Fig. 4] Fig. Figure 4 is a block diagram illustrating the functional design of the wireless communication system according to the embodiment. [ Fig. 5] Fig. Figure 5 is a sequence diagram that represents the operating sequence of the wireless communication system according to the embodiment when no error occurs in the wireless communication between the first communication unit and a communication device. [ Fig. 6] Fig. Figure 6 is a sequence diagram that illustrates the operating sequence of the wireless communication system according to the embodiment when a fault occurs in the wireless communication between the first communication unit and the communication device. [ Fig. 7] Fig. Figure 7 is a sequence diagram that illustrates the operation of the wireless communication system according to the embodiment when a fault occurs in: the wireless communication between the first communication unit and the communication device; and the wireless communication between the second communication unit and the communication device. [Description of the embodiments]

[0026] An embodiment of the present invention is described in detail below with reference to the drawings. Note that the embodiment described below represents an essential or specific example of the present invention. The numerical values, shapes, materials, elements, arrangement and connection of elements, steps, arrangement of steps, etc., specified in the following embodiment are merely examples and are not intended to limit the scope of the present invention. Among the elements described in the following embodiment, those not described in any of the independent claims are described as optional elements. [Execution format] 1. Overview of the wireless communication system

[0027] First, an overview of the wireless communication system 2 according to one embodiment is given with reference to Fig. 1, Fig. 2 to Fig. 3 described. Fig. Figure 1 is a diagram that provides an overview of the wireless communication system 2 according to the embodiment. Fig. Figure 2 is a schematic diagram to illustrate the transmission of a FOUP 10 in the wireless communication system 2 according to the embodiment. Fig. Figure 3 is a schematic diagram to illustrate the positional relationship between the control device 22, the first communication unit 24 and the second communication unit 28 in the transport vehicle 4 according to the embodiment.

[0028] As in Fig. As shown in Figure 1, the wireless communication system 2 is a system that is, for example, set up within a semiconductor manufacturing apparatus. The wireless communication system 2 comprises a transport vehicle 4 (an example of a moving body), a semiconductor manufacturing apparatus 6, and a communication device 8.

[0029] The transport vehicle 4 is an overhead transport vehicle for transporting FOUPs 10 (e.g., objects) that house semiconductor wafers and is a so-called Overhead Hoist Transfer (OHT). The transport vehicle 4 is an unmanned vehicle that moves along a rail 12 provided on the ceiling of a semiconductor manufacturing device. Several (e.g., hundreds) of transport vehicles 4 are arranged in the semiconductor manufacturing device, but in Fig. Figure 1 shows only one transport vehicle 4 for illustrative purposes.

[0030] The transport vehicle 4 has a main vehicle body 14, a gripping section 16, a lifting mechanism 18 and a side mechanism 20.

[0031] The vehicle body 14 is designed to have a hollow structure with an approximately rectangular shape when viewed in the XY plane, and travels along the rail 12. The FOUP 10 can be stored in the vehicle body 14.

[0032] The gripping section 16 is mounted in the vehicle main body 14. The gripping section 16 suspends and holds the FOUP 10 by gripping its upper end.

[0033] The lifting mechanism 18 is mounted in the vehicle body 14. The lifting mechanism 18 is a mechanism for raising and lowering the gripping section 16 in a vertical direction (Z-axis direction) and is made, for example, of metal.

[0034] The side mechanism 20 is mounted in the vehicle body 14. The side mechanism 20 is a mechanism for moving the gripping section 16 and the lifting mechanism 18 in a horizontal direction (Y-axis direction) and is, for example, made of metal. The side mechanism 20 is positioned between a stowed position (not shown in the figure) within the vehicle body 14 and a protruding position (see Fig. 2), which extends laterally from the main vehicle body 14, is displaceable. When the side mechanism 20 is in the stowed position, the gripping section 16 and the lifting mechanism 18 are arranged inside the main vehicle body 14. However, when the side mechanism 20 is in the protruding position, the gripping section 16 and the lifting mechanism 18 are arranged outside the main vehicle body 14.

[0035] For example, when the FOUP 10 is transported between the transport vehicle 4 and the loading port 38 (described later) of the semiconductor manufacturing device 6, the transport vehicle 4 initially stops directly above the loading port 38. In this state, after the side mechanism 20 has been moved from the stowed position to the protruding position, the lifting mechanism 18 lowers the gripping section 16 from the transport vehicle 4 to the vicinity of the loading port 38 and transfers the FOUP 10 between the gripping section 16 and the loading port 38. Specifically, the lifting mechanism 18 grips the FOUP 10 at the loading port 38 with the gripping section 16 or unloads the FOUP 10 from the gripping section 16 to the loading port 38.Then, when the transfer of the FOUP 10 is complete, the side mechanism 20 moves from the protruding position to the stowed position after the lifting mechanism 18 has lifted the gripping section 16 from near the loading opening 38 to the transport vehicle 4.

[0036] As in Fig. 2 and Fig. As shown in Figure 3, the transport vehicle 4 also has a control device 22, a first communication unit 24 (for example, a specific communication unit), a first antenna 26, a second communication unit 28 (for example, one or more other communication units), and a second antenna 30.

[0037] The control unit 22 is mounted in the main body of the vehicle 14 and centrally controls the operation of all parts of the transport vehicle 4.

[0038] The first communication unit 24 is connected (wired) to the control device 22 via a serial cable 32. This allows the first communication unit 24 to transmit and receive information to and from the control device 22 via serial communication using a communication protocol such as RS-232C, which utilizes the serial cable 32. The first communication unit 24 also transmits and receives information to and from the communication device 8 via wireless communication using a predefined channel (frequency band). The first communication unit 24 transmits and receives information to and from the communication device 8 via short-range wireless communication. Short-range wireless communication refers to wireless communication that uses, for example, Bluetooth Low Energy (BLE).

[0039] The first antenna 26 is an antenna for the first communication unit 24 and is connected to the first communication unit 24 via a cable (not shown in the figure).

[0040] The second communication unit 28 is connected to the first communication unit 24 via a serial cable 34 (for example, a communication cable). The second communication unit 28 thus transmits and receives information to and from the first communication unit 24 via serial communication using a communication protocol such as RS-232C, which utilizes the serial cable 34. The second communication unit 28 also transmits and receives information regarding wireless communication between the first communication unit 24 and the communication device 8 via the serial cable 34 to and from the first communication unit 24.In other words, the first communication unit 24 and the second communication unit 28 exchange information via wireless communication, which both the first communication unit 24 and the second communication unit 28 conduct with the communication device 8. The second communication unit 28 also transmits and receives information to and from the communication device 8 via wireless communication using the predetermined channel. In other words, the first communication unit 24 and the second communication unit 28 conduct wireless communication with the communication device 8 using the same predetermined channel. The first communication unit 24 and the second communication unit 28 transmit and receive information to and from the communication device 8 via short-range wireless communication. As in . Fig. As shown in Figure 3, the first communication unit 24 and the second communication unit 28 are arranged at a predetermined distance from each other.

[0041] The second antenna 30 is an antenna for the second communication unit 28 and is connected to the second communication unit 28 via a cable (not shown in the figure). As in Fig. As shown in Figure 3, the first antenna 26 and the second antenna 30 are arranged diagonally on the vehicle body 14, for example, when viewed in the XY plane.

[0042] The semiconductor manufacturing device 6 is a device, for example, for processing or temporarily storing semiconductor wafers held in FOUPs 10, and is located directly below the rail 12. The semiconductor manufacturing device 6 has: a delivery inlet and outlet 36 for loading and unloading FOUPs 10; and a loading port 38 (an example of a transfer device) located near the delivery inlet and outlet 36. The loading port 38 is a loading port for transferring FOUPs 10. The loading port 38 transfers FOUPs 10 to and from the gripping section 16 of the transport vehicle 4 and also passes FOUPs 10 to the semiconductor manufacturing device 6 via the delivery inlet and outlet 36.

[0043] It should be noted that a semiconductor manufacturing apparatus provides for several (e.g., several thousand) semiconductor manufacturing devices 6, but in Fig. Figure 1 shows only one semiconductor manufacturing device 6 for illustrative purposes. Furthermore, the present embodiment describes a semiconductor manufacturing device 6 with a single loading port 38; the semiconductor manufacturing device 6 is not limited to this example and could also have multiple loading ports 38.

[0044] The communication device 8 is a communication device for mediating communication between the transport vehicle 4 and the loading port 38 of the semiconductor manufacturing device 6. The communication device 8 is, for example, placed on the surface of the semiconductor manufacturing device 6 and connected to the loading port 38 of the semiconductor manufacturing device 6 via a parallel cable 40. This allows the communication device 8 to transmit and receive information to and from the loading port 38 of the semiconductor manufacturing device 6. The E84 communication sequence of SEMI is applied to the communication between the communication device 8 and the transport vehicle 4. Although the semiconductor manufacturing device provides the same number of communication devices 8 as loading ports 38, in Fig. 1 For illustrative purposes only one communication device 8 is shown.

[0045] In the wireless communication system 2 described above, when FOUP 10, which is placed at the loading port 38, is picked up by the transport vehicle 4, or when FOUP 10 is unloaded by the transport vehicle 4 at the loading port 38, control signals (information) are exchanged between the first communication unit 24 (or the second communication unit 28) of the transport vehicle 4 and the communication device 8 via the E84 communication sequence. The E84 communication sequence uses a multi-process interlock sequence. This sequence prevents the transition to the next step unless a specific control signal is switched off when FOUP 10 is being transferred between the transport vehicle 4 and the loading port 38. 2. Functional configuration of the wireless communication system

[0046] The functional configuration of the wireless communication system 2 according to the embodiment is described with reference to Fig. 4 described. Fig. Figure 4 is a block diagram that illustrates the functional configuration of the wireless communication system 2 according to the embodiment.

[0047] As in Fig. As shown in Figure 4, the transport vehicle 4 has a control device 22, a first communication unit 24 and a second communication unit 28.

[0048] The control unit 22 controls the first communication unit 24 to perform various processing operations. For example, the control unit 22 instructs the first communication unit 24 to initiate wireless communication with the communication device 8 when the transport vehicle 4 arrives at a position directly above the loading opening 38, to which the transport vehicle 4 is to transport the FOUP 10 (see Fig. 1) The control device 22 is implemented, for example, by a processor that reads and executes a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0049] 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 transmits and receives information to and from the communication device 8 via wireless communication using the specified channel. Furthermore, if an error 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 initiate wireless communication with the communication device 8.

[0050] 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 device 22 via serial cable 34, the first communication unit 24, and serial cable 32. If a fault occurs in the wireless communication between the first communication unit 24 and the communication device 8, the second communication unit 28, at the instruction of the first communication unit 24, initiates wireless communication with the communication device 8 using the designated channel. In other words, while one of the first communication units 24 and the second communication unit 28 is conducting wireless communication with the communication device 8, the other of the first communication units 24 and the second communication unit 28 is not conducting wireless communication with the communication device 8.

[0051] The loading port 38 of the semiconductor manufacturing device 6 has a communication device 42 and a control device 44.

[0052] The communication device 42 transmits and receives information via a parallel cable 40 (see Fig. 1) to and from the communication device 8.

[0053] The control unit 44 controls the communication unit 42 to perform various operations. In particular, the control unit 44 performs an interlock operation via the E84 communication sequence to transfer the FOUP 10 to and from the transport vehicle 4. The control unit 44 also performs operations to transfer the FOUP 10 to the semiconductor manufacturing device 6 and from there via the delivery input and output 36 (see Fig. 1) by. The control device 44 is implemented, for example, by a processor that reads and executes a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0054] The communication device 8 has a communication unit 46 and a control unit 48.

[0055] The communication device 46 transmits and receives information via a parallel cable 40 to and from the loading opening 38. The communication device 46 also transmits and receives information via wireless communication to and from the transport vehicle 4.

[0056] The control unit 48 controls the communication unit 46 to perform various processing operations. The control unit 48 is implemented, for example, by a processor that reads and executes a software program recorded on a recording medium such as a hard disk or semiconductor memory. 3. Operation of the wireless communication system

[0057] The operation of the wireless communication system 2, when no interference occurs in the wireless communication between the first communication unit 24 and the communication device 8, is described with reference to Fig. 5 described. Fig. Figure 5 is a sequence diagram that represents the operating sequence of the wireless communication system 2 according to the embodiment when no interference occurs in the wireless communication between the first communication unit 24 and the communication device 8.

[0058] As in Fig. As shown in Figure 5, when the transport vehicle 4 arrives at a position directly above the loading opening 38, the control unit 22 of the transport vehicle 4 transmits information relating to wireless communication for the communication between the first communication unit 24 and the communication device 8 (for example, information regarding the wireless communication between the first communication unit 24 and the communication device 8) via the serial cable 32 to the first communication unit 24 (S101). Thus, the first communication unit 24 receives the information relating to the settings for wireless communication from the control unit 22 of the transport vehicle 4.The information relating to the wireless communication settings includes, for example, (a) the address of the communication device 8, which is a connection destination (a unique identifier such as an ID), (b) a channel used for wireless communication, and (c) a transmission output value or the like. In this case, the second communication unit 28 shares the information relating to the wireless communication settings with the first communication unit 24 via the serial cable 34. The control unit 22 of the transport vehicle 4 could transmit data for transmission to the communication device 8 (e.g., a control signal to be used in the E84 communication sequence) to the first communication unit 24, along with the information relating to the wireless communication settings.

[0059] Then the control unit 22 of the transport vehicle 4 instructs the first communication unit 24 to start wireless communication with the communication device 8 (S102).

[0060] Then, the first communication unit 24 of the transport vehicle 4 transmits information to the communication device 8 (S103) on the instruction of the control unit 22 for establishing wireless communication with the communication device 8.

[0061] Since no interference occurs 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 transport vehicle 4. The communication device 8 then transmits a response to the information to the first communication unit 24 (S104).

[0062] This establishes wireless communication between the first communication unit 24 and the communication device 8, and the first communication unit 24 performs the communication for the locking processing using the E84 communication sequence (S105).

[0063] Next, the operation of the wireless communication system 2 is described when a fault occurs in the wireless communication between the first communication unit 24 and the communication device 8, with reference to Fig. 6. Fig. Figure 6 is a sequence diagram that illustrates the operation of the wireless communication system 2 according to the embodiment when a fault occurs in the wireless communication between the first communication unit 24 and the communication device 8.

[0064] In the Fig. In the case shown in Figure 6, it is assumed that no error occurs in the wireless communication between the second communication unit 28 and the communication device 8.

[0065] As in Fig. As shown in Figure 6, when the transport vehicle 4 arrives at a position directly above the loading opening 38, steps S201 and S202 are performed as steps S101 and S102 in the sequence diagram in Fig. 5 carried out.

[0066] After step S202, the first communication unit 24 of the transport vehicle 4 transmits information to the communication device 8 on the instruction of the control unit 22 (S203) to establish wireless communication with the communication device 8. Since an error occurs in the wireless communication between the first communication unit 24 and the communication device 8 in this case, the communication device 8 cannot receive any information from the first communication unit 24 of the transport vehicle 4.

[0067] Causes for the error in wireless communication between the first communication unit 24 and the communication device 8 could include, for example, the side mechanism 20 or similar, which is moved from the stowed position to the protruding position and thereby physically blocks the wireless communication path between the first communication unit 24 and the communication device 8.

[0068] Then the first communication unit 24 of the transport vehicle 4 repeats the transmission of information to the communication device 8 several times until a response is received from the communication device 8 (S204 and S205).

[0069] If the communication device 8 fortunately receives information from the first communication unit 24 of the transport vehicle 4, the communication device 8 transmits a response to the information to the first communication unit 24. However, even in this case, the radio signal strength of the response from the communication device 8 is extremely low (e.g., -80 dBm or less) due to the failed wireless communication between the first communication unit 24 and the communication device 8. For this reason, the first communication unit 24 ignores the response from the communication device 8.

[0070] If the first communication unit 24 of the transport vehicle 4 cannot receive a response from the communication device 8 even after a predetermined time has elapsed since the first communication unit 24 first sent information to the communication device 8 (i.e., if a timeout occurs in wireless communication), the first communication unit 24 terminates the wireless communication with the communication device 8 (S206).

[0071] The first communication unit 24 of the transport vehicle 4 then instructs the second communication unit 28 to initiate wireless communication with the communication device 8 (S207). In this case, the first communication unit 24 transmits information concerning the wireless communication settings to the second communication unit 28 via serial cable 34. The content instructing the second communication unit 28 to initiate wireless communication could include information about the last wireless communication between the first communication unit 24 and the communication device 8. This information could be, for example, transmitted data from the communication that took place immediately prior (such as sequence numbers specified in packets, etc.).Based on the instruction from the first communication unit 24, the second communication unit 28 transmits information to the communication device 8 to establish wireless communication with the communication device 8 (S208).

[0072] Since no interference occurs in the wireless communication between the second communication unit 28 and the communication device 8 in this case, the communication device 8 can receive information from the second communication unit 28 of the transport vehicle 4. The communication device 8 then transmits a response to the information to the second communication unit 28 (S209).

[0073] This establishes wireless communication between the second communication unit 28 and the communication device 8; the second communication unit 28 transmits information indicating the manufacturing process to the first communication unit 24 (S210) and executes communication with the communication device 8 for locking processing via the E84 communication sequence (S211).

[0074] If an error occurs during wireless communication between the first communication unit 24 and the communication device 8, the first communication unit 24 could transfer the wireless communication to the second communication unit 28. This would allow the second communication unit 28 to take over the wireless communication with the communication device 8.

[0075] Next, the operation of the wireless communication system 2 is described when a fault occurs in each of the following cases: during wireless communication between the first communication unit 24 and the communication device 8, and during wireless communication between the second communication unit 28 and the communication device 8, with reference to Fig. 7. Fig. Figure 7 is a sequence diagram that illustrates the operation of the wireless communication system 2 according to the embodiment when a fault occurs in each of the following cases: during wireless communication between the first communication unit 24 and the communication device 8, and during wireless communication between the second communication unit 28 and the communication device 8.

[0076] In the Fig. In the case to be presented in section 7, it is assumed that the fault in the wireless communication between the first communication unit 24 and the communication device 8 is rectified after the fault occurs.

[0077] As in Fig. As shown in Figure 7, if the transport vehicle 4 is positioned directly above the loading opening 38, steps S301 and S302 are performed like steps S101 and S201 in the sequence diagram in Fig. 5 carried out.

[0078] After step S302, the first communication unit 24 of the transport vehicle 4 transmits information to the communication device 8 on the instruction of the control unit 22 (S303) to establish wireless communication with the communication device 8. Since an error occurs in the wireless communication between the first communication unit 24 and the communication device 8 in this case, the communication device 8 cannot receive any information from the first communication unit 24 of the transport vehicle 4.

[0079] Then the first communication unit 24 of the transport vehicle 4 repeats the transmission of information to the communication device 8 several times until a response is received from the communication device 8 (S304 and S305).

[0080] If the communication device 8 fortunately receives information from the first communication unit 24 of the transport vehicle 4, the communication device 8 transmits a response to the information to the first communication unit 24. However, even in this case, the radio signal strength of the response from the communication device 8 is extremely low due to the failure of wireless communication between the first communication unit 24 and the communication device 8. For this reason, the first communication unit 24 ignores the response from the communication device 8.

[0081] If the first communication unit 24 of the transport vehicle 4 cannot receive a response from the communication device 8 even after a predetermined time has elapsed, after the first communication unit 24 has first sent information to the communication device 8, the first communication unit 24 terminates the wireless communication with the communication device 8 (S306).

[0082] The first communication unit 24 of the transport vehicle 4 then instructs the second communication unit 28 to initiate wireless communication with the communication device 8 (S307). In this case, the first communication unit 24 transmits information relating to the wireless communication settings to the second communication unit 28 via the serial cable 34.

[0083] Subsequently, the second communication unit 28 of the transport vehicle 4 transmits information to the communication device 8 (S308) on the instructions of the first communication unit 24 to establish wireless communication with the communication device 8. Since an error occurs in the wireless communication between the second communication unit 28 and the communication device 8 in this case, the communication device 8 cannot receive any information from the second communication unit 28 of the transport vehicle 4.

[0084] Then the second communication unit 28 of the transport vehicle 4 repeats the transmission of information to the communication device 8 several times until a response is received from the communication device 8 (S309 and S310).

[0085] If the first communication unit 24 of the transport vehicle 4 cannot receive a response from the communication device 8 even after a predetermined time has elapsed, following the initial transmission of information by the second communication unit 28 to the communication device 8, the first communication unit 24 instructs the second communication unit 28 to terminate the wireless communication with the communication device 8 (S311). Upon receiving the instruction to terminate the wireless communication, the second communication unit 28 could transmit information about the last wireless communication with the communication device 8 to the first communication unit 24 as a response.

[0086] Afterwards, the first communication unit 24 of the transport vehicle 4 restarts wireless communication with the communication device 8 (S312) and, on instruction from the control unit 22 (S313), transmits information to the communication device 8 for establishing wireless communication with the communication device 8. In this case, the communication device 8 can receive information from the first communication unit 24 when the disturbance in the wireless communication between the first communication unit 24 and the communication device 8 has been resolved.

[0087] The communication device 8 then transmits a response to the information to the first communication unit 24 (S314).

[0088] This establishes wireless communication between the first communication unit 24 and the communication device 8, and the first communication unit 24 performs communication with the communication device 8 for locking processing via the E84 communication sequence (S315). 4. Beneficial effects

[0089] In the present embodiment, the first communication unit 24 and the second communication unit 28 share information regarding wireless communication, and the same predefined channel is used for wireless communication between the first communication unit 24 and the communication device 8, as well as for wireless communication between the second communication unit 28 and the communication device 8, as described above. This allows the second communication unit 28 to immediately initiate wireless communication with the communication device 8, even if an error occurs in the wireless communication between the first communication unit 24 and the communication device 8.

[0090] The first communication unit 24 and the second communication unit 28 are arranged at a predetermined distance from each other. This can increase the probability of successful wireless communication with the communication device 8 by using the second communication unit 28 if a failure in wireless communication between the first communication unit 24 and the communication device 8 occurs due to a physical blockage, for example, by obstacles in the wireless communication path between the first communication unit 24 and the communication device 8. (Other variants)

[0091] Although the wireless communication system according to the present invention has been described above based on the aforementioned embodiment, the present invention is not limited to this embodiment. Embodiments obtained by modifications of the embodiment that could be devised by those skilled in the art, and other embodiments resulting from any combination of elements of the embodiment, also fall within the scope of the present invention.

[0092] In the embodiment described above, the control unit 22 of the transport vehicle 4 instructs the first communication unit 24 to initiate wireless communication with the communication device 8 when the transport vehicle 4 arrives at a position directly above the loading opening 38. However, the instruction of the control unit 22 is not limited to this example. The control unit 22 of the transport vehicle 4 could designate the second communication unit 28 as the primary unit and instruct the second communication unit 28 to initiate wireless communication with the communication device 8. In this case, the control unit 22 transmits information concerning the wireless communication settings for communication between the second communication unit 28 and the communication device 8 to the second communication unit 28 via serial cable 32, the first communication unit 24, and serial cable 34.

[0093] Alternatively, depending on the location to which the FOUP 10 is to be transported, the control device 22 could designate either the first communication unit 24 or the second communication unit 28 as the communication unit that first performs wireless communication with the communication device 8.

[0094] Although the transport vehicle 4 in the aforementioned embodiment has two communication units (first communication unit 24 and second communication unit 28), the transport vehicle 4 is not limited to this example and could have three or more communication units.

[0095] In the embodiment described above, the control device 22 and the first communication unit 24 are wired and connected, and the first communication unit 24 and the second communication unit 28 are wired and connected, but the connections are not limited to this example. For instance, each of the first communication unit 24 and the second communication unit 28 could be directly wired and connected to the control device 22.

[0096] In the aforementioned embodiment, a movable body is applied to a transport vehicle in the above embodiment, but the application of the movable body is not limited to this example, and a movable body could, for example, be applied to an unmanned transport vehicle that moves on the ground.

[0097] In the aforementioned embodiment, each element could be implemented using dedicated hardware or by executing a software program suitable for that element. Each element could be implemented by a program executor, such as a CPU or processor, which reads and executes a software program recorded on a storage medium, such as a hard drive or semiconductor memory. [Industrial applicability]

[0098] The wireless communication system according to the present invention can, for example, be applied to semiconductor manufacturing systems for transporting FOUPs by transport vehicles that move along rails, which are provided, for example, on a ceiling. [List of reference symbols] 2 Wireless communication systems 4 Transport vehicles 6 Semiconductor manufacturing equipment 8 Communication device 10 FOUP 12 rail 14 Vehicle body 16 Gripping section 18 Lifting mechanism 20-sided mechanism 22, 44, 48 Control device 24 first communication unit 26 first antenna 28 second communication unit 30 second antenna 32, 34 serial cable 36 Incoming and outgoing deliveries 38 Loading opening 40 parallel cables 42, 46 Communication device QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-36816

[0005]

Claims

[1] Wireless communication system comprising: a transport vehicle moving along a track and carrying an object; and a communication device connected to a transmission device transmitting the object to and from the transport vehicle and performing wireless communication with the transport vehicle, where the transport vehicle has several communication units that are arranged at a predetermined distance from each other and connected to each other via a communication cable, a specific communication unit from among the multiple communication units performs wireless communication with the communication device using a predetermined channel, one or more other communication units, with the exception of the specific communication unit, exchange information from the multiple communication units with the specific communication unit via the communication cable, the information being information relating to the wireless communication between the specific communication unit and the communication device, and If an error occurs in the wireless communication between the specified communication unit and the communication device, one or more other communication units will initiate wireless communication with the communication device using the specified channel. [2] Wireless communication system according to claim 1, wherein, if an error occurs in the wireless communication between the specified communication unit and the communication device, the specified communication unit transfers the wireless communication to one or more other communication units. [3] Wireless communication system according to claim 1, wherein the information relating to wireless communication includes wireless communication settings between the specified communication unit and the communication device. [4] Wireless communication system according to claim 1, wherein the transport vehicle also has a control device that controls the transport vehicle, the specific communication unit is connected to the control device and can communicate with it, transmitting information to and receiving information from the control device, and one or more other communication units transmit information to and receive information from the control unit via the communication cable and the specific communication unit. [5] Wireless communication system according to any one of claims 1 to 4, wherein the communication cable is a serial cable and one or more other communication units exchange information with the specified communication unit regarding wireless communication via serial communication using the serial cable. [6] Wireless communication system according to claim 1, wherein the transport vehicle further comprises a control device which, according to a location to which the object is to be transferred, determines the specific communication unit which performs the wireless communication with the communication device, wherein the specific communication unit is determined from the multiple communication units. [7] Transport vehicle moving along a track and carrying an object, wherein the transport vehicle has: several communication units arranged at a predetermined distance from each other and connected to each other via a communication cable, wherein a specific communication unit from among several communication units performs wireless communication with a communication device using a predetermined channel, wherein the communication device is connected to a transmission device that transmits the object to and from the transport vehicle, wherein one or more other communication units, with the exception of the specific communication unit from among the multiple communication units, exchange information with the specific communication unit via the communication cable, the information being information relating to the wireless communication between the specific communication unit and the communication device, and If an error occurs in the wireless communication between the specified communication unit and the communication device, one or more other communication units will initiate wireless communication with the communication device using the specified channel. [8] Control method in a wireless communication system comprising: a movable body that transports an object; and a communication device that is in communication connection with a transmission device that transmits the object to and from the movable body and performs wireless communication with the movable body, wherein the movable body has several communication units that are arranged at a predetermined distance from each other and connected to each other via a communication cable, the control method exhibits: Conducting wireless communication with the communication device using a predetermined channel by a specific communication unit; Sharing information regarding wireless communication between the specific communication unit and the communication device by one or more other communication units with the specific communication unit via the communication cable, wherein the one or more other communication units exclude the specific communication unit from the multiple communication units; and initiating wireless communication with the communication device using the specified channel by one or more other communication units when an error occurs in the wireless communication between the specified communication unit and the communication device.

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