Wireless communication method and wireless communication system

Abstract

This conveyance system comprises a plurality of conveyance carriages and a plurality of communication devices. The communication device has a one-to-one connection with each of a plurality of load ports through which an object being conveyed is transferred to and from the conveyance carriage. The conveyance carriage uses a carriage communication unit to wirelessly transmit a signal to the plurality of communication devices prior to communication associated with transfer of the object being conveyed. On the basis of a communication state of the transmission performed on the plurality of communication devices, the carriage communication unit transmits and receives communication data to and from a specific communication device among the plurality of communication devices via a communication path, at least a portion of which is a wireless communication path.

Description

Wireless communication method and wireless communication system

[0001] The present invention relates to wireless communication performed in a transport system including a plurality of transport vehicles.

[0002] Patent Document 1 discloses a transport system including multiple transport vehicles. In the transport system of Patent Document 1, the overhead traveling vehicle stops traveling above a load port provided in semiconductor manufacturing equipment and transfers semiconductor wafers and the like between the load port and the overhead traveling vehicle. A communication device is installed in the semiconductor manufacturing equipment. The overhead traveling vehicle performs interlock communication with the communication device via wireless communication.

[0003] In Patent Document 1, a specific transport vehicle transmits a first signal to a plurality of communication devices, the first signal being finalized as a specific communication device among the plurality of communication devices. The specific communication device as the final destination receives the first signal from the specific transport vehicle via a communication path that passes through another communication device among the plurality of communication devices.

[0004] In Patent Document 1, even if a specific communication device cannot directly receive a first signal from a specific transport vehicle due to a communication failure, the specific communication device can indirectly receive the first signal via a communication path via another communication device, thereby making wireless communication in interlock communication of the transport system redundant.

[0005] Patent No. 6923148

[0006] The above-mentioned Patent Document 1 does not disclose how to determine a communication path via another communication device.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to efficiently determine a communication path in a configuration in which wireless communication is made redundant. Means to solve the problem and effects

[0008] The problem to be solved by the present invention is as described above. Next, the means for solving this problem and the effects thereof will be explained.

[0009] According to a first aspect of the present invention, there is provided a wireless communication method applicable to the following transport system. That is, the transport system includes a plurality of transport vehicles and a plurality of communication devices. The transport vehicle transports an object to be transported. The communication devices are connected one-to-one to each of a plurality of facilities between which the object is transferred and which are connected to the transport vehicle. The plurality of communication devices are capable of communicating with each other. In this transport system, the wireless communication method is used by the transport vehicle to perform wireless communication with the facilities to transfer the object to and from the transport vehicle. The wireless communication method includes a first step and a second step. In the first step, a vehicle communication unit provided in a specific transport vehicle among the plurality of transport vehicles wirelessly transmits signals to the multiple communication devices prior to communication associated with the transfer of the object. In the second step, the vehicle communication unit transmits and receives communication data to a specific communication device among the multiple communication devices via a communication path, at least a portion of which is a wireless communication path, based on a communication state regarding the transmission performed to the multiple communication devices in the first step.

[0010] This makes it possible to efficiently determine the communication path in the second step based on the communication in the first step in a configuration where wireless communication is made redundant.

[0011] The wireless communication method preferably has the following configuration: In other words, in the first step, the signal wirelessly transmitted to the plurality of communication devices is one in which the specific communication device among the plurality of communication devices is specified as a final destination. In the second step, the specific communication device that is the final destination receives the signal from the vehicle communication unit via a communication path that passes through another communication device among the plurality of communication devices. The wireless communication method includes a third step and a fourth step. In the third step, position information of the specific transport vehicle in the first step and identification information of the other communication device that was present on the communication path in the second step are stored in association with each other. In the fourth step, based on the information stored in the third step, the vehicle communication unit transmits the communication data to the other communication device, with the specific communication device as the final destination.

[0012] As a result, in the third step, the communication path used in the second step can be stored in association with the position of the transporting vehicle. In the fourth step, the communication path can be determined quickly using the information stored in the third step. Therefore, this method is suitable for cases where it is desirable to change the communication path from the transporting vehicle communication unit to the final destination communication device depending on the position of the transporting vehicle.

[0013] In the wireless communication method, it is preferable to store the following: In the third step, the posture information of the specific transport vehicle in the first step and the identification information of the other communication device that was present on the communication path in the second step are associated with each other.

[0014] As a result, in the third step, the communication path used in the second step can be stored in association with the position of the transporting vehicle as well as the posture of the transporting vehicle. In the fourth step, the communication path can be determined quickly using the information stored in the third step. Therefore, this method is suitable for cases where it is desirable to change the communication path from the transporting vehicle communication unit to the final destination communication device depending on the posture of the transporting vehicle.

[0015] In the wireless communication method, it is preferable that the specific transport vehicle includes a plurality of antennas, and in the third step, (1) position information of the specific transport vehicle in the first step, (2) information specifying the antenna that performed communication in the second step among the plurality of antennas, and (3) identification information of the other communication device that was present on the communication path in the second step are stored in association with each other.

[0016] As a result, in the third step, the communication path used in the second step can be appropriately stored in association with the position of the antenna used by the bogie communication unit for wireless communication.

[0017] According to a second aspect of the present invention, there is provided a wireless communication method applicable to the following transport system. That is, the transport system includes a plurality of transport vehicles and a plurality of communication devices. The transport vehicle transports an object. The communication devices are connected one-to-one to each of a plurality of facilities between which the object is transferred and which are connected to the transport vehicle. The plurality of communication devices are capable of communicating with each other. In this transport system, the wireless communication method is used by the transport vehicle to perform wireless communication with the facilities to transfer the object. The wireless communication method includes a fifth step, a sixth step, a seventh step, an eighth step, and a ninth step. In the fifth step, a signal including final destination communication device information specifying a specific communication device among the plurality of communication devices as a final destination is wirelessly transmitted to the multiple communication devices using a vehicle communication unit provided in a specific transport vehicle among the multiple transport vehicles prior to communication associated with the transfer of the object. In the sixth step, preliminary result information is stored. The preliminary result information is at least one of the communication status of the transmission performed to the multiple communication devices in the fifth step and preliminary transmission response information indicating the response of the communication device to the transmission. In the seventh step, a vehicle communication unit provided in the transport vehicle transmits and receives communication data to and from a specific communication device designated as the final destination among the multiple communication devices via a communication path, at least a portion of which is a wireless communication path. In this transmission and reception, whether any other communication device among the multiple communication devices will relay the transmission and reception of the communication data, and if so, which communication device will perform the relay, are determined based on the preliminary result information stored in the sixth step. In the eighth step, the preliminary result information of the sixth step or information based thereon is stored as recommended communication information in association with the final destination communication device information and transport vehicle information of the fifth step. The transport vehicle information is information about the transport vehicle that transmitted the signal in the fifth step.In the ninth step, the carriage communication unit of the transport carriage transmits and receives communication data to and from a specific communication device designated as the final destination among the plurality of communication devices via a communication path at least a part of which is a wireless communication path. In this transmission and reception, whether or not any other communication device among the plurality of communication devices will relay the transmission and reception of the communication data, and if so, which communication device will relay the communication data, is determined based on the recommended communication information stored in the eighth step.

[0018] As a result, in a configuration in which wireless communication is redundant, preliminary result information, which is the result of the communication performed in the preliminary step 5, can be acquired in the sixth step. In the seventh step, a communication path can be appropriately determined based on the preliminary result information acquired in the sixth step, and communication can be performed with the communication device that is the final destination. By storing recommended communication information based on the preliminary result information acquired in the sixth step in the eighth step, a communication path can be efficiently determined using the stored information in the communication in the ninth step.

[0019] In the wireless communication method, it is preferable that the signal transmission in the fifth step is performed using a plurality of wireless communication channels, and the communication data transmission and reception in the seventh and ninth steps are performed using the plurality of channels.

[0020] As a result, in a situation where wireless communication is possible over multiple channels, the preliminary communication is also performed over multiple channels, making it possible to appropriately determine the communication path.

[0021] In the wireless communication method, it is preferable that the recommended communication information is stored in association with at least one of information specifying the type of the transporting vehicle, information specifying the position of the transporting vehicle, and information specifying the attitude of the transporting vehicle in the eighth step.

[0022] As a result, in the ninth step, a communication route can be efficiently determined in accordance with important conditions when selecting a communication route.

[0023] In the wireless communication method, it is preferable that the recommended communication information in the eighth step includes at least one of (1) information identifying the vehicle communication unit that is recommended to transmit and receive the communication data, (2) information identifying a wireless communication antenna that is recommended to be used to transmit and receive the communication data, (3) information identifying another communication device among the plurality of communication devices that is recommended to relay communication between the vehicle communication unit and the communication device specified as the final destination, and (4) wireless transmission power that is recommended when the vehicle communication unit transmits the communication data.

[0024] This allows appropriate communication to be carried out in the ninth step.

[0025] In the wireless communication method, it is preferable that a storage unit included in each of the plurality of communication devices is capable of storing the recommended communication information in the eighth step, and the plurality of communication devices share the recommended communication information stored in the storage unit through communication between the communication devices.

[0026] As a result, in the ninth step, the recommended communication information stored in the eighth step can be acquired from any of the plurality of communication devices, thereby facilitating acquisition of information necessary for determining a communication route in the ninth step.

[0027] In the wireless communication method, it is preferable that the preliminary result information stored in the sixth step includes a communication state related to the transmission of the signal in the fifth step. The communication state includes a radio wave strength indicating the radio wave strength when the vehicle communication unit receives a signal from the communication device, or a received radio wave strength indicating the radio wave strength when the communication device receives a signal from the vehicle communication unit. In the seventh step, whether any other communication device among the plurality of communication devices will relay the transmission and reception of the communication data, and if so, which communication device will relay the communication data, is determined based on a result of comparing the received radio wave strengths for the plurality of communication devices.

[0028] This allows the communication route to be appropriately determined in the seventh step based on the received radio wave intensity.

[0029] In the wireless communication method, it is preferable that the preliminary result information stored in the sixth step includes a communication state related to the transmission of the signal in the fifth step. The communication state includes a radio wave strength indicating the radio wave strength when the vehicle communication unit receives a signal from the communication device, or a received radio wave strength indicating the radio wave strength when the communication device receives a signal from the vehicle communication unit. If a communication device whose received radio wave strength is equal to or greater than a threshold is found while the fifth step and the sixth step are being performed for each of the plurality of communication devices, the preliminary result information for that communication device is stored, and then the fifth step and the sixth step are aborted.

[0030] This allows the time required for trial communication to be substantially reduced.

[0031] In the wireless communication method, it is preferable that the transport system includes a control server that controls the plurality of transport vehicles, and in the eighth step, the recommended communication information is stored in a storage unit included in the control server.

[0032] This allows the recommended communication information commonly applied to a plurality of transporting vehicles to be collected and stored in the control server, thereby preventing inconsistencies in the information.

[0033] In the wireless communication method, it is preferable that the transport vehicle is capable of transferring the transported object while stopped at a position selected from a plurality of positions relative to the facility, and in the eighth step, the stopping position of the specific transport vehicle is stored as information specifying the position of the specific transport vehicle.

[0034] As a result, in the ninth step, the communication path can be determined efficiently, taking into account the stopping position of the transport vehicle relative to the facility, and communication can be carried out.

[0035] In the wireless communication method, it is preferable that the transport vehicle is capable of transferring the transported object while stopped in a posture selected from a plurality of postures relative to the equipment, and in the eighth step, the stopping posture of the specific transport vehicle is stored as information specifying the posture of the specific transport vehicle.

[0036] As a result, in the ninth step, the communication path can be efficiently determined by appropriately considering the stopping posture of the transport vehicle relative to the facility, and communication can be performed.

[0037] In the wireless communication method, it is preferable that the transport vehicle moves in a first direction and a second direction on a track configured in a lattice pattern, the second direction being perpendicular to the first direction, and the transport vehicle transfers the transported object to the equipment installed below the track.

[0038] This makes it possible to efficiently determine communication paths based on prior communication in a transport system in which there is a wide variety of stopping positions for transport vehicles.

[0039] In the wireless communication method, it is preferable that the plurality of communication devices are connected to each other by cables.

[0040] This allows stable communication between multiple communication devices.

[0041] According to a third aspect of the present invention, there is provided a wireless communication system having the following configuration. That is, the wireless communication system includes a plurality of transport vehicles, a vehicle communication unit, and a plurality of communication devices. The transport vehicles transport objects to be transported. The vehicle communication unit is disposed on each of the plurality of transport vehicles. The communication devices are connected one-to-one to each of a plurality of pieces of equipment between which the objects are transferred to and from the transport vehicles. The plurality of communication devices are capable of communicating with each other. The vehicle communication unit provided on a specific transport vehicle among the plurality of transport vehicles that transfers the objects to wirelessly transmits signals to the plurality of communication devices. Based on the communication state of the transmission made to the plurality of communication devices, the vehicle communication unit transmits and receives communication data to a specific communication device among the plurality of communication devices via a communication path, at least a portion of which is a wireless communication path.

[0042] This makes it possible to efficiently determine a communication path for transmitting and receiving communication data based on prior communication in a configuration where wireless communication is made redundant.

[0043] 1 is a plan view schematically showing a transport system to which a wireless communication system according to an embodiment of the present invention is applied. FIG. 2 is a block diagram of a wireless communication system. FIG. 3 is a block diagram showing in detail the configuration of a carriage communication unit and a communication device. FIG. 4 is a diagram showing a frame of a trial signal. FIG. 5 is a diagram explaining possible stopping positions and attitudes for a load port. FIG. 6 is a diagram explaining possible stopping positions and attitudes for a load port. FIG. 7 is a diagram explaining possible stopping positions and attitudes for a load port. FIG. 8 is a diagram showing a frame of a trial response signal. FIG. 9 is a flowchart explaining the first half of the trial communication process. FIG. 10 is a flowchart explaining the second half of the trial communication process. FIG. 11 is a flowchart explaining the first half of the process for determining a recommended combination of a carriage communication unit and a communication device. FIG. 12 is a flowchart explaining the second half of the process for determining a recommended combination of a carriage communication unit and a communication device. FIG. 13 is a flowchart showing the process for performing trial communication and SEMI E84 communication. FIG. 14 is a diagram explaining a frame for notifying a trial communication result. FIG. 15 is a diagram showing the contents of storage related to the trial communication result. FIG. 16 is a flowchart showing the process for performing trial communication and SEMI E84 communication in a second embodiment.

[0044] Next, an embodiment of the present invention will be described with reference to the drawings. First, an overview of a transport system 1 will be described with reference to Fig. 1. Fig. 1 is a plan view schematically showing the configuration of a transport system 1 according to a first embodiment.

[0045] The transport system 1 is installed in a facility such as a semiconductor manufacturing plant. The transport system 1 can transport any object, such as a FOUP that stores semiconductor wafers. FOUP is an abbreviation for Front Opening Unified Pod. As shown in FIG. 1 , the transport system 1 includes a track 90 and multiple transport vehicles 30a and 30b. In this embodiment, the transport vehicles 30a and 30b are configured as suspended traveling vehicles. In the following description, when there is no particular need to identify each of the two transport vehicles 30a and 30b, the transport vehicles may be denoted by the reference numeral 30.

[0046] The track 90 is suspended from the ceiling by a mounting member (not shown). The track 90 includes a plurality of first tracks 91 and a plurality of second tracks 92. The first tracks 91 and the second tracks 92 are both linear tracks. The first tracks 91 and the second tracks 92 are arranged so as to be perpendicular to each other in a plan view. Hereinafter, the longitudinal direction of the first tracks 91 may be referred to as a first direction D1, and the longitudinal direction of the second tracks 92 may be referred to as a second direction D2.

[0047] The transport vehicle 30 travels along the track 90 while suspended from the track 90. ​​Specifically, each of the transport vehicles 30a, 30b can travel in a first direction D1 by rotating drive wheels (not shown) while supported by two adjacent first tracks 91. The transport vehicles 30a, 30b can also travel in a second direction D2 by rotating drive wheels while supported by two adjacent second tracks 92. The transport vehicles 30a, 30b are provided with a position change mechanism (not shown), which can change the orientation (position) of the transport vehicles 30a, 30b in a plan view in 90° increments. In FIG. 1, the position of each of the transport vehicles 30a, 30b is indicated by an arrow pointing forward in the traveling direction of the transport vehicle 30.

[0048] The travel area of ​​the transport vehicle 30 includes a lattice area. In the lattice area, first tracks 91 and second tracks 92 are arranged in a lattice pattern. Specifically, the first tracks 91 are arranged at equal intervals (at an interval that allows the transport vehicles 30a and 30b to travel between two adjacent first tracks 91), and the second tracks 92 are arranged at equal intervals (at an interval that allows the transport vehicles 30a and 30b to travel between two adjacent second tracks 92). When an area surrounded by two adjacent first tracks 91 and two adjacent second tracks 92 is called a unit block, the first tracks 91 and the second tracks 92 are formed so that unit blocks of the same shape are arranged in a matrix in the first direction D1 and the second direction D2. This allows the transport vehicle 30 to travel in both the first direction D1 and the second direction D2 regardless of which unit block it is located in.

[0049] Taking note of this feature, the transport vehicle 30 of this embodiment is sometimes called a grid type. Instead of a grid type transport vehicle, for example, an overhead hoist transfer (OHT) that travels along a long, narrow track can also be used as the transport vehicle. OHT is an abbreviation for overhead hoist transfer.

[0050] Below the track 90, processing equipment 50, load ports (equipment) 60a-60d, etc. are arranged. The processing equipment 50 is equipment that performs various processes on semiconductor wafers and the like. In this embodiment, four load ports 60a-60d are arranged side by side. Each load port 60a-60d is connected to a space where the processing equipment 50 performs processing. In the following, when there is no particular need to identify each of the four load ports 60a-60d, the load ports may be referred to by the reference numeral 60. The number of load ports 60 varies depending on the processing equipment 50, and is generally between two and six. In this embodiment, the case where the number of load ports 60 is four will be described, but this is not limiting.

[0051] The semiconductor wafers (more specifically, FOUPs 95 containing semiconductor wafers) transported by the transport vehicle 30 are placed on one of the four load ports 60a to 60d. In FIG. 1, an example in which the FOUP 95 is placed on the load port 60a is shown by a dotted line. The semiconductor wafers are then transported from the FOUP 95 by, for example, a robot arm, and processed in the processing equipment 50. The FOUP 95 containing the processed semiconductor wafers is then transported from the load port 60a to the equipment for the next process by the same or a different transport vehicle 30.

[0052] As shown in FIG. 2 , the transport system 1 of this embodiment includes a control server 10 and a wireless communication device 20 in addition to the transport vehicle 30 described above.

[0053] The control server 10 functions as a host control device of the transport system 1. The control server 10 includes a computer equipped with an arithmetic unit. The control server 10 controls the running / stopping of the multiple transport vehicles 30 and the transfer of FOUPs to the transport vehicles 30. The control server 10 includes a control unit 11, a storage unit 12, and a communication unit 13.

[0054] The storage unit 12 includes a non-volatile storage unit (not shown) and a volatile storage unit. The non-volatile storage unit stores programs for operating the control server 10 and various information related to the control of the transport vehicle 30. The volatile storage unit is used for temporary storage during control processing.

[0055] The communication unit 13 is connected to a first communication unit 23 included in the wireless communication device 20 via a cable 81. The cable 81 may be, for example, a known LAN cable, but is not limited to this. The communication unit 13 can send and receive various information by communicating with the first communication unit 23.

[0056] The wireless communication device 20 mediates communication of various information between the control server 10 and the multiple transport vehicles 30. The various information includes control information for the transport vehicles 30 and status information for the transport vehicles 30 (for example, a status indicating whether a FOUP 95 is being transported). The wireless communication device 20 is configured to include a computer equipped with a calculation unit. The wireless communication device 20 includes a control unit 21, a storage unit 22, a first communication unit 23, and a second communication unit 24.

[0057] The control unit 21 controls communication with the control server 10 and wireless communication with the transport vehicle 30 .

[0058] The storage unit 22 includes a nonvolatile storage unit (not shown) and a volatile storage unit. The nonvolatile storage unit stores programs and the like for controlling the wireless communication device 20. The volatile storage unit is used for temporary storage during control processing.

[0059] As described above, the first communication unit 23 can send and receive signals through communication with the communication unit 13 .

[0060] The second communication unit 24 is configured to be capable of wireless communication with the communication unit 33 provided in the transporting cart 30. Any method of wireless communication may be used, but for example, it may be one that complies with a known wireless LAN standard.

[0061] The transport vehicle 30 travels along a track 90 on the ceiling of the semiconductor factory in accordance with commands received from the control server 10. Although only one processing device 50 is depicted in FIG. 1 , in reality, a plurality of processing devices 50 are arranged in the travel area of ​​the transport vehicle 30. The transport vehicle 30 can travel between the plurality of processing devices 50 while carrying a FOUP 95. The transport vehicle 30 can transfer the FOUP 95 between the transport vehicle 30 and the load port 60 of the processing device 50.

[0062] The transport vehicle 30 includes a vehicle control unit 31, a memory unit 32, a communication unit 33, and a vehicle communication unit 34.

[0063] The carriage control unit 31 controls the travel of the transport carriage 30 and the transfer of the FOUP 95 .

[0064] The storage unit 32 includes a non-volatile storage unit (not shown) and a volatile storage unit. The non-volatile storage unit stores programs and the like for controlling the transport vehicle 30. The volatile storage unit stores various types of information. The various types of information include information related to the control of the transport vehicle 30 and information related to the transfer of FOUPs. The volatile storage unit is used for temporary storage during control processing.

[0065] As described above, the communication unit 33 performs wireless communication with the second communication unit 24 included in the wireless communication device 20. Although Fig. 2 shows an example in which one communication unit 33 is provided for one transport vehicle 30, a plurality of communication units 33 may be provided.

[0066] The carriage communication units 34a, 34b are arranged on each of the multiple transport carriages 30. Each of the carriage communication units 34a, 34b can communicate wirelessly with the communication devices 70a to 70d arranged on the processing device 50 side. Any form of wireless communication can be used, but for example, close proximity wireless communication such as BLE communication can be used. BLE is an abbreviation for Bluetooth Low Energy. Bluetooth is a registered trademark. In the following, when there is no particular need to identify each of the two carriage communication units 34a, 34b, the carriage communication units may be referred to by the reference numeral 34.

[0067] Although the vehicle communication units 34a and 34b are omitted from FIG. 1 , the vehicle communication unit 34a is disposed at the front of the transport vehicle 30a, and the vehicle communication unit 34b is disposed at the rear of the transport vehicle 30a. The positions of the two vehicle communication units 34a and 34b are the same on both the transport vehicles 30a and 30b. On the transport vehicle 30, each vehicle communication unit 34a and 34b can be identified, for example, by using a number counted sequentially from the front. This number is used, for example, in a process for identifying a pair of communication partners between the vehicle communication unit 34 and the communication device 70, which will be described later.

[0068] The transport vehicle 30a is equipped with two antennas 39a, 39b. In the following description, when there is no particular need to identify each of the two antennas 39a, 39b, the antennas may be denoted by the reference numeral 39. The two antennas 39a, 39b are connected one-to-one to the vehicle communication units 34a, 34b. Therefore, identifying the vehicle communication unit 34 used for wireless communication, for example, by using a number, is synonymous with identifying the antenna 39 used for wireless communication. The relative positions of the two antennas 39a, 39b are the same between the two transport vehicles 30a, 30b.

[0069] The detailed configuration of the vehicle communication unit 34 is shown in Fig. 3. Each vehicle communication unit 34 includes a computer having a calculation device. As shown in Fig. 3, the vehicle communication unit 34 includes a control unit 35, a storage unit 36, a first communication unit 37, and a second communication unit 38.

[0070] The control unit 35 controls communication with the carriage control unit 31 and communication with the communication device 70 .

[0071] The storage unit 36 ​​includes a non-volatile storage unit (not shown) and a volatile storage unit. The non-volatile storage unit stores various information including programs for operating the bogie communication unit 34 and communication log information. The volatile storage unit is used for temporary storage during control processing.

[0072] The first communication unit 37 is connected to the carriage control unit 31 via a cable 82, and performs communication with the carriage control unit 31. The cable 82 is arbitrary, and may be, for example, a known LAN cable or a serial communication cable such as RS232C.

[0073] The second communication unit 38 uses the antenna 39 to perform close proximity wireless communication with the communication device 70 .

[0074] The processing apparatus 50 shown in FIG. 2 takes out a wafer from the FOUP 95 placed on the load port 60 and performs appropriate processing.

[0075] Communication devices 70a to 70d are arranged corresponding to the load ports 60a to 60d in the processing device 50. In the following, when there is no particular need to identify each of the four communication devices 70a to 70d, the communication devices may be denoted by the reference numeral 70.

[0076] The four communication devices 70a to 70d are connected to the four load ports 60a to 60d in a one-to-one correspondence. Specifically, the communication device 70a and the load port 60a are connected in a one-to-one relationship via a cable 83. The communication device 70b and the load port 60b are connected in a one-to-one relationship via a cable 83. The communication device 70c and the load port 60c are connected in a one-to-one relationship via a cable 83. The communication device 70d and the load port 60d are connected in a one-to-one relationship via a cable 83. These cables 83 may be, for example, parallel I / O cables based on the SEMI E84 standard.

[0077] 2, four communication devices 70a to 70d are arranged for one processing device 50. The load ports 60a to 60d can communicate with the corresponding communication devices 70a to 70d, respectively.

[0078] The cart communication unit 34 and the communication device 70 mediate the sending and receiving of signals communicated between the load port 60 and the transport cart 30 to transfer transported items, specifically signals related to interlock control (interlock signals and interlock response signals which are response signals to the interlock signals), via wireless communication.

[0079] Interlock control is a control in which a specific operation is prohibited unless a specific condition is met. By performing interlock control in the transport system 1, it is possible to implement a restriction that prevents the process from proceeding to the next step unless a specific condition is met when transferring a FOUP 95 from the transport vehicle 30 to the load port 60a. For example, in order for a specific transport vehicle 30a to proceed to the step of transferring the FOUP 95 to a specific load port 60a, the following two conditions must be met. The first condition is that the transport vehicle 30a transmits an interlock signal to the load port 60a, which includes an instruction to confirm whether or not the transport vehicle 30a is in a state where transfer is possible. The second condition is that the transport vehicle 30a receives an interlock response signal from the load port 60a, indicating that transfer is currently possible. This interlock control ensures that the FOUP 95 can be transferred from the specific transport vehicle 30a to the specific load port 60a.

[0080] The communication device 70 wirelessly transmits and receives an interlock signal and an interlock response signal to and from the carriage communication unit 34 provided on the transport carriage 30 .

[0081] The multiple communication devices 70a to 70d are connected to each other so that they can communicate with each other. Therefore, interlock signals and interlock response signals can be transmitted and received between the multiple communication devices 70a to 70d. For example, the multiple communication devices 70a to 70d are connected to each other by a cable 84. The cable 84 is optional, but could be, for example, a well-known RS485 cable. Because a wired connection is used, communication between the multiple communication devices 70a to 70d can be more stable than in the case of a wireless connection. The multiple communication devices 70a to 70d may also be configured to communicate with each other wirelessly.

[0082] In response to a command from the carriage control unit 31, an interlock signal is wirelessly transmitted from a selected one of the carriage communication units 34 to a selected one of the communication devices 70. Which carriage communication unit 34 and communication device 70 are selected is determined based on the result of a prior trial communication. The trial communication will be described later.

[0083] The interlock signal transmitted by the carriage communication unit 34 must ultimately reach the communication device 70 corresponding to the load port 60 to which or from which the FOUP 95 is to be transferred. Hereinafter, the communication device 70 corresponding to the load port 60 where the transfer operation is performed may be referred to as the "final destination." The following description will be given assuming that the communication device 70a is the final destination. The interlock signal may be wirelessly transmitted directly to the communication device 70a of the final destination, or may be wirelessly transmitted directly to one of the communication devices 70b-70d (e.g., communication device 70b) different from the final destination and then transmitted via wired communication to the communication device 70a of the final destination. In the latter case, the communication device 70b relays communication between the carriage communication unit 34 and the communication device 70a of the final destination. Communication between the communication device 70b and the communication device 70a is performed via a cable 84.

[0084] In either case, the communication device 70a, which is the final destination and receives the interlock signal, transmits an interlock response signal. The interlock response signal travels in the reverse direction along the communication path used when the interlock signal was transmitted and reaches the vehicle communication unit 34. The vehicle control unit 31 determines whether or not it is possible to proceed to the next process based on the content of the interlock response signal received by the vehicle communication unit 34.

[0085] Next, a detailed description will be given of the configuration of the communication device 70. The communication device 70 includes a computer having a calculation unit. As shown in FIG. 3 , the communication device 70 includes a control unit 71, a storage unit 72, a first communication unit 73, a second communication unit 74, and a third communication unit 75.

[0086] The control unit 71 controls near field communication with the carriage communication unit 34 provided in the transport carriage 30, and also controls communication with the load port 60. In addition, the control unit 71 controls wired communication with other communication devices 70.

[0087] The storage unit 72 includes a non-volatile storage unit (not shown) and a volatile storage unit. The non-volatile storage unit stores various information including programs for operating the communication device 70 and communication log information. The volatile storage unit is used for temporary storage during control processing.

[0088] The first communication unit 73 is connected to the control computer of the load port 60 via the aforementioned cable 83. The first communication unit 73 can send and receive signals to and from the load port 60. These signals can be, for example, parallel I / O signals based on the SEMI E84 standard, but are not limited to this.

[0089] The second communication unit 74 is connected to the second communication unit 74 of the other communication device 70 via the above-mentioned cable 84. The second communication unit 74 can send and receive signals to and from the second communication unit 74 included in the other communication device 70. The communication can be performed according to RS485, for example.

[0090] The third communication unit 75 performs close proximity wireless communication with the second communication unit 38 included in the carriage communication unit 34 .

[0091] Next, the trial communication that is performed before the exchange of the interlock signal and the interlock response signal will be described in detail.

[0092] When transmitting and receiving signals related to interlock control via wireless communication in semiconductor manufacturing factories, etc., communication failures must be taken into consideration. Possible causes of communication failures include, but are not limited to, reflection of radio waves due to the surrounding environment, radiation of radio waves from various devices including multiple processing devices 50, and dead points in communication due to overlapping of radio waves.

[0093] In this embodiment, in order to deal with communication failures, multiple communication devices 70 arranged in one processing device 50 are communicatively connected to each other via cables 84 to form a group. Consider a case where the vehicle communication unit 34 is unable to communicate directly wirelessly with a specific communication device 70 (typically, a communication device 70 corresponding to a load port 60 to which or from which a FOUP 95 is to be transferred). Even in this case, if the vehicle communication unit 34 can communicate directly wirelessly with any other communication device 70 belonging to the same group, signals can be essentially transmitted and received with the target communication device 70 via communication between groups. This achieves redundancy in the communication path and ensures stable communication.

[0094] The trial communication is performed to determine which of the multiple communication paths available as described above is suitable for the transport vehicle 30 to communicate with a specific communication device 70. In this embodiment, the interlock signal can be transmitted from either of the two vehicle communication units 34 (34a, 34b). The direct wireless transmission destination of the interlock signal may be any of the four communication devices 70. Additionally, the close proximity wireless communication of this embodiment can use one arbitrarily selected from three candidate channels. Therefore, by transmitting and receiving appropriate data for each of the 2 × 4 × 3 = 24 combinations, the most preferable communication path can be identified from the perspective of communication stability, etc. Hereinafter, channel numbers #1, #2, and #3 may be used to identify each channel. However, the number of candidate channels used for close proximity wireless communication is not limited to three and can be determined arbitrarily.

[0095] In the transport vehicle 30, the antennas 39a, 39b provided on each of the two vehicle communication units 34a, 34b are located at different positions. Therefore, the radio wave transmission conditions differ depending on which of the two vehicle communication units 34 is used for wireless communication. In the processing device 50, the antennas (not shown) provided on each of the four communication devices 70 are located at different positions. Therefore, the radio wave reception conditions differ depending on which of the four communication devices 70 receives the radio waves. In addition, radio wave interference and the like differ depending on which of the three channels is used for close proximity wireless communication.

[0096] Taking this into consideration, in this embodiment, in principle, radio waves are transmitted and received in all of the 24 combinations described above. This makes it possible to obtain the combination of the vehicle communication unit 34 as the signal source and the communication device 70 as the signal destination that is estimated to provide the best wireless communication. The obtained combination is stored in the storage unit 72 provided in the communication device 70 as recommended communication combination information, which will be described later.

[0097] The trial communication will be briefly explained below.

[0098] In this embodiment, as shown in FIG. 1, a wireless communication system 5 is constructed by a plurality of transport carts 30a, 30b, cart communication units 34a, 34b provided on each of the plurality of transport carts 30a, 30b, and a plurality of communication devices 70a to 70d.

[0099] In response to a command from the bogie control unit 31, the bogie communication unit 34a wirelessly transmits a trial signal to the communication device 70a using channel #1. Upon receiving the signal, the communication device 70a wirelessly transmits a trial response signal to the bogie communication unit 34a. As will be described in detail later, the trial response signal includes an RSSI value. RSSI is an abbreviation for Received Signal Strength Indication. The RSSI (received signal strength) value essentially indicates the radio wave strength on the receiving side. Therefore, the RSSI value included in the trial response signal is measured when the communication device 70a receives the trial signal from the bogie communication unit 34a.

[0100] The vehicle communication unit 34a receives the trial response signal from the communication device 70a. When receiving the response signal, the vehicle communication unit 34a can measure the RSSI value. The vehicle control unit 31 stores the RSSI value measured when receiving the trial response signal in the memory unit 32 together with the RSSI value included in the trial response signal.

[0101] The carriage communication unit 34a similarly performs trial communication with the communication device 70a using the other channels #2 and #3, respectively.

[0102] The cart communication unit 34a also performs trial communication using three channels #1, #2, and #3 with communication devices 70b, 70c, and 70d, respectively, and links each communication device 70 to the RSSI value contained in the trial response signal and stores it in the memory unit 32.

[0103] Next, the trolley communication unit 34b similarly performs trial communication using three channels #1, #2, and #3 with communication devices 70a, 70b, 70c, and 70d, respectively, in response to instructions from the trolley control unit 31, and links each communication device 70 to the RSSI value contained in the trial response signal and stores it in the memory unit 32.

[0104] 4 shows a frame of the trial signal transmitted from the carriage communication unit 34 to the communication device 70. As shown in Fig. 4, the frame of the trial signal includes a final destination communication device ID, a trial communication destination communication device ID, a carriage communication unit ID, a channel number, transport carriage information, and carriage position and attitude information.

[0105] The "final destination communication device ID" refers to the ID of the communication device 70 connected to the load port 60 to which or from which the FOUP 95 is to be transferred. The ID is identification information for uniquely identifying an apparatus. The ID may take any format, but for example, an identification number can be used. A MAC address can also be used as the ID. MAC is an abbreviation for Media Access Control. For example, when a FOUP 95 being transported by the transport vehicle 30a needs to be transferred to the load port 60a, the "final destination communication device ID" describes the identification information of the communication device 70a. In this way, the trial signal is transmitted by specifying the final destination communication device 70, similar to the interlock signal described above.

[0106] The "trial communication destination communication device ID" describes the ID of the communication device 70 that will be the other party in the trial communication. For example, when the transport vehicle 30a directly transmits a trial signal to the communication device 70b via close proximity wireless communication, the "trial communication destination communication device ID" describes identification information of the communication device 70b.

[0107] The "carriage communication unit ID" describes the ID of the carriage communication unit that transmits the trial signal in the transport carriage 30a. For example, if the carriage communication unit 34a is the transmission source of the trial signal, the "carriage communication unit ID" describes the identification information of the carriage communication unit 34a.

[0108] In the "channel number" field, a value indicating the channel number used for transmitting the trial signal is written.

[0109] The "transport vehicle information" field contains information specifying the type of the transport vehicle 30a. The type of the transport vehicle 30a is, for example, information specifying whether the transport vehicle 30a is a ceiling-suspended type or a road-surface type, or whether the transport vehicle 30a is a grid type.

[0110] The "cart position and attitude information" describes information that specifies the position and attitude of the transport cart relative to the load port 60 that is the transfer destination or the transfer source at the time of transmitting the trial signal. Therefore, the "cart position and attitude information" is a type of position information and also a type of attitude information.

[0111] This will be explained in more detail below. As shown in Figure 5, consider a case in which four load ports 60a-60d equipped to a processing device 50 are arranged in a row along the aisle 52 of the transport vehicle 30a. Although a suspended type transport vehicle 30 is shown as an example in Figure 1, it is assumed here that the transport vehicle 30 is a road-traveling type. Because the housing of the processing device 50 is located on the opposite side of the aisle 52 from the load ports 60a-60d, when the transport vehicle 30a is traveling on the road, the load ports 60a-60d can only be accessed from the aisle 52 side.

[0112] Consider a case where a transport vehicle 30a traveling along the aisle 52 from another position stops at a position on the aisle 52 facing the load port 60a. When the transport vehicle 30a transfers a FOUP 95 to the load port 60a, three possible cases are possible depending on the orientation of the transport vehicle 30a: the load port 60a is positioned adjacent to the front of the transport vehicle 30a (R1), adjacent to the right (R2), or adjacent to the left (R3). Theoretically, there are four possible orientations for the transport vehicle 30a in 90° increments, but due to the structure of the transport system 1, a situation in which the load port 60a is adjacent to the rear of the transport vehicle 30a is excluded. In this way, there are three possible orientations (postures) for the transport vehicle 30a. The transport vehicle 30a horizontally extends a known lateral mechanism toward the load port 60a and transfers the FOUP to the load port 60a. In FIG. 5, the lateral mechanism is shown in dashed lines in its extended state.

[0113] Space is formed above the load ports 60a-60d and the processing equipment 50. Therefore, when the transport vehicle 30a travels on the ceiling, it can stop directly above the load port 60a, as shown in FIG. 6. In this case, the orientation (posture) of the transport vehicle 30a can be considered in four different positions in 90° increments, as shown by R4 to R7 in FIG. 6. Because the transport vehicle 30a stops directly above the load port 60a, there is no need to extend the lateral mechanism to transfer the FOUP 95.

[0114] When the transport vehicle 30a travels on the ceiling, it can also stop at a position adjacent to the load port 60a on the opposite side of the aisle 52, as shown in Figure 7. In this case, there are four possible orientations (postures) of the transport vehicle 30a in 90° increments, as shown by R8 to R11 in Figure 7. The transport vehicle 30a extends its lateral mechanism toward the load port 60a and transfers the FOUP to the load port 60a.

[0115] In this embodiment, a specific numerical value is assigned in advance to each combination of the stop position and attitude of the transporting vehicle 30a shown above in R1 to R11. The numerical value is described in the "cart position and attitude information." Therefore, the "cart position and attitude information" simultaneously specifies the stop position and stop attitude of the transporting vehicle 30a relative to the load port 60a, which is the transfer destination or source position.

[0116] The frames of the trial response signals returned by the communication devices 70a to 70d in response to the trial signal are shown in Fig. 8. As shown in Fig. 8, the frame of the trial response signal includes the vehicle communication unit ID, the channel number, the final destination communication device ID, the trial communication destination communication device ID, the communication device side RSSI value, the communication device cooperation status, past recommended communication combination information, and past recommended wireless power value.

[0117] The "vehicle communication unit ID," "channel number," "final destination communication device ID," and "trial communication destination communication device ID" are described with the same values ​​as the contents of the trial signal frame received by the communication devices 70a to 70d. For example, when the communication device 70b returns a trial response signal to the vehicle communication unit 34a, the "trial communication destination communication device ID" describes the identification information of the communication device 70b.

[0118] The “RSSI value on the communication device side” describes the RSSI value when the communication device 70 receives a trial signal frame from the bogie communication unit 34 .

[0119] The "communication device cooperation status" describes information indicating whether each of the four communication devices 70a to 70d belonging to the same group is in a cooperation state. A cooperation state refers to a state in which a device performs an operation to forward a signal it has received to another communication device. The "communication device cooperation status" may further describe information specifying which of the four communication devices 70a to 70d is operating as the master device for RS485 communication.

[0120] The "past recommended communication combination information" describes information that specifies a combination of the cart communication unit 34 and the communication device 70 that is recommended for good wireless communication when trial communication has been performed in the past. The recommended combination is typically, but is not limited to, the combination that results in the highest RSSI value.

[0121] For example, consider a case where the communication device 70 of the final destination is the communication device 70a, the transport vehicle 30a is a grid-type vehicle, and the position and attitude of the transport vehicle 30a are in the situation shown in R4 in Fig. 6. In this case, if trial communication has been performed in the past under similar circumstances, information indicating which of the two vehicle communication units 34a and 34b as the transmission source and the four communication devices 70a, 70b, 70c, and 70d as the communication partner had the highest RSSI value is described in the "past recommended communication combination information." If trial communication has not been performed in the past, information indicating this is described in the "past recommended communication combination information."

[0122] The "past recommended wireless power value" describes the wireless transmission power recommended when the bogie communication unit 34 performs wireless communication in accordance with the "past recommended communication combination information" when trial communication has been performed in the past.

[0123] The past recommended communication combination information and the past recommended wireless power values ​​are both types of past recommended communication information, which will be described later.

[0124] Next, the trial communication process will be described with reference to the flowcharts of FIGS.

[0125] When the process starts, the carriage control unit 31 instructs the carriage communication unit 34a to transmit a trial signal frame to the communication device 70a using channel #1 (step S101).

[0126] The communication device 70a that has received the trial signal transmits a response signal frame, and the vehicle communication unit 34a waits until it receives the response signal frame (step S102).

[0127] If trial communication has been performed in the past under similar circumstances, the response signal returned by the communication device 70 contains recommended communication information based on the results of the past trial communication. The vehicle communication unit 34a checks whether the response signal frame contains valid past recommended communication information (step S103). If the response signal contains past recommended communication information, the trial communication is stopped and processing is terminated. This avoids trial communication that overlaps with past communication and allows communication for interlock control to be started early.

[0128] Depending on the synchronization status of the wireless communication, the vehicle communication unit 34a may receive a response signal returned by one of the other communication devices 70b to 70d. The vehicle communication unit 34a checks, based on the frame of the response signal, whether the communication device that sent the response signal matches the communication device 70a with which the trial communication is to be performed (step S104). If the communication device 70a does not match the communication device with which the trial communication is to be performed, the timing of the trial communication is slightly delayed (step S105) and the trial communication is performed again. This can promote synchronization of the trial communication between the vehicle communication unit 34a and the communication device 70.

[0129] If the communication device 70a that received the response signal matches the communication device of the trial communication destination, the vehicle control unit 31 stores the RSSI value measured at the time of receiving the response signal in the storage unit 32 (step S106).The vehicle control unit 31 also stores the RSSI value included in the frame of the response signal in the storage unit 32 (step S107).

[0130] The RSSI value obtained in step S107 indicates the communication state regarding the transmission of the trial signal. The RSSI value obtained in step S106 indicates the communication state regarding the response of the communication device 70a to the trial signal. Therefore, the RSSI value obtained in step S106 is a type of advance transmission response information. Both of the two RSSI values ​​are information on the results of communications performed in advance. Therefore, the two RSSI values ​​are a type of advance result information.

[0131] The bogie control unit 31 determines whether both of the two RSSI values ​​are equal to or greater than a predetermined threshold (step S108). If the two RSSI values ​​are equal to or greater than the threshold, it is expected that a sufficiently good communication state can be achieved by the combination of the bogie communication unit 34a and the communication device 70a, without the need for other comparisons, and the process ends. By terminating the trial communication midway, communication for interlock control can be started early.

[0132] The carriage control unit 31 and the carriage communication unit 34a repeat the processing of steps S101 to S108 while changing the wireless communication channel from #1 to #2 to #3 (steps S109 and S110).

[0133] When trial communication is completed for all channels #1 to #3, the trolley control unit 31 and the trolley communication unit 34a repeat the processing of steps S101 to S110 while switching the trial communication destination between communication device 70a, communication device 70b, etc. (steps S111 and S112 in Figure 10).

[0134] When the trial communication is completed for all of the communication devices 70a to 70d, the vehicle control unit 31 switches the transmission source of the trial signal from the vehicle communication unit 34a to the vehicle communication unit 34b, and repeats the processing of steps S101 to S112 (steps S113 and S114). When the trial communication is completed for all of the vehicle communication units 34a and 34b, the series of processing ends.

[0135] The combination of the vehicle communication units 34a, 34b and the communication devices 70a to 70d that produces the highest RSSI value in trial communication can be obtained, for example, by performing the processing shown in Figures 11 and 12. This processing will be described below.

[0136] First, various initializations are performed in the bogie control unit 31 (step S201). In this initialization process, a first loop counter is initialized to 1. The first loop counter identifies the communication device 70; for example, a value of 1 indicates the communication device 70a, and a value of 2 indicates the communication device 70b. In this embodiment, since the number of communication devices 70 belonging to one group is four, the value that the first loop counter can take is an integer between 1 and 4.

[0137] The second loop counter is also similarly initialized to 1. The second loop counter identifies the vehicle communication unit 34, and for example, a value of 1 indicates vehicle communication unit 34a, and a value of 2 indicates vehicle communication unit 34b. In this embodiment, since the number of vehicle communication units 34 is two, the value that the second loop counter can take is an integer between 1 and 2.

[0138] Next, with respect to the RSSI value when the bogie communication unit 34 receives a response signal frame from the communication device 70, a first comparison variable is initialized to a value (e.g., a lower limit value) indicating that the radio wave strength is sufficiently small.

[0139] With respect to the RSSI value when the communication device 70 receives a command signal frame from the bogie communication unit 34, a second comparison variable is initialized to a value (e.g., a lower limit value) that indicates that the radio wave strength is sufficiently small.

[0140] Next, a first index variable is initialized to, for example, zero, for the RSSI value when the bogie communication unit 34 receives a frame of a response signal from the communication device 70 .

[0141] A second index variable is initialized, for example to zero, for the RSSI value when the communication device 70 receives a frame of a command signal from the bogie communication unit 34 .

[0142] Next, the following processes (a) and (b) are repeated for all combinations of the communication device 70 and the bogie communication unit 34 using the first loop counter and the second loop counter.

[0143] (a) The bogie control unit 31 reads from the storage unit 32 the RSSI value when the bogie communication unit 34 indicated by the value of the second loop counter receives a trial response signal frame from the communication device 70 indicated by the value of the first loop counter (step S202). The bogie control unit 31 compares the RSSI value read from the storage unit 32 with the value of the first comparison variable (step S203). If the read RSSI value indicates a radio wave intensity higher than the value of the first comparison variable, the value of the first comparison variable is updated to the RSSI value, and further, the first index variable is updated to the value of the first loop counter (step S204).

[0144] (b) The vehicle control unit 31 reads from the storage unit 32 the RSSI value when the communication device 70 indicated by the value of the first loop counter receives a trial signal frame from the vehicle communication unit 34 indicated by the value of the second loop counter (step S205). The vehicle control unit 31 compares the RSSI value read from the storage unit 32 with the value of the second comparison variable (step S206). If the read RSSI value indicates a radio wave intensity higher than the value of the second comparison variable, the value of the second comparison variable is updated to the RSSI value, and the second index variable is updated to the value of the second loop counter (step S207).

[0145] The processes of steps S202 to S207 are repeated while the first loop counter is incremented by one until it exceeds 4 (steps S208 and S209).

[0146] The processing of steps S201 to S209 is repeated while the second loop counter is incremented by 1 until it exceeds 2 (steps S210 and S211). Each time this is repeated, the value of the first loop counter is initialized to 1 (step S212).

[0147] When the iterative processing using the double loop is completed, the value of the first index variable and the value of the second index variable indicate the combination of the vehicle communication unit 34 and the communication device 70 that provides the highest RSSI value. The vehicle control unit 31 generates a value specifying the recommended combination of the vehicle communication unit 34 and the communication device 70 based on the value of the first index variable and the value of the second index variable, and stores the value in the storage unit 32 (step S213). At this time, the recommended vehicle communication unit 34 is specified using the above-mentioned number. On the other hand, the recommended communication device 70 is specified using, for example, an ID.

[0148] The value of the second comparison variable represents the RSSI value of the communication device 70 when the combination of the vehicle communication unit 34 and the communication device 70 obtained in step S213 is used for wireless communication. The vehicle control unit 31 compares the value of this second comparison variable with a predetermined threshold (step S214). If the value of the second comparison variable is equal to or greater than the threshold, excessively good communication quality is expected. Therefore, the vehicle control unit 31 sets a value lower than normal as the recommended wireless power value for the vehicle communication unit 34 and stores it in the storage unit 32 (step S215). The extent to which the recommended wireless power value should be lower than normal is determined based on the value of the second comparison variable. If the value of the second comparison variable is less than the threshold, the vehicle control unit 31 sets a normal value as the recommended wireless power value for the vehicle communication unit 34 and stores it in the storage unit 32 (step S216). The series of processes then ends.

[0149] It is expected that good wireless communication will be performed between the recommended cart communication unit 34 and the communication device 70. Therefore, by reducing the wireless transmission power of the cart communication unit 34 to a range that does not impede communication, it is possible to achieve energy conservation while suppressing interference with close proximity wireless communication performed between other cart communication units 34 and other communication devices 70 in the wireless communication system 5.

[0150] As explained in step S108 of the flowchart shown in Fig. 9, the RSSI value may be determined to be equal to or greater than the threshold value, and the trial communication may be terminated at that point. In this case, a value specifying the combination of the vehicle communication unit 34 and the communication device 70 when an RSSI value equal to or greater than the threshold value is obtained may be stored in the storage unit 32 as a recommended combination of communication devices. Therefore, the processing shown in Figs. 11 and 12 may be omitted except for the portions corresponding to steps S214 to S216.

[0151] The recommended communication combinations and recommended wireless power values ​​obtained as described above are each a type of recommended communication information. Hereinafter, the recommended communication combinations and recommended wireless power values ​​may be collectively referred to as recommended communication information.

[0152] Next, the trial communication and the subsequent SEMI E84 communication for interlock control will be described with reference to the flowchart in Fig. 13. Here, the case where the transport vehicle 30a communicates for interlock control with the communication device 70a corresponding to the load port 60a to which the FOUP 95 is to be transferred will be described.

[0153] Before performing communication for interlock control, the carriage control unit 31 of the transport carriage 30a performs the trial communication described above for the combination of the carriage communication units 34a and 34b and the communication devices 70a, 70b, 70c, and 70d (step S301). This process is the same as that described with reference to Figures 9 and 10, so its description will be omitted.

[0154] The vehicle control unit 31 determines whether past recommended communication information is present in the trial response signal received by the vehicle communication unit 34 from the communication device 70 during the trial communication (step S302). This determination is substantially the same as the determination in step S103 shown in FIG. 9.

[0155] If the trial response signal does not substantially include past recommended communication information, the vehicle control unit 31 determines a combination of the vehicle communication unit 34 and the communication device 70 that is recommended for achieving good communication based on the results of the trial communication (step S303). The obtained combination is stored in the storage unit 32 as recommended communication combination information. This determination process corresponds to steps S201 to S213 in the flowcharts shown in Figures 11 and 12. Here, it is assumed that the combination of the vehicle communication unit 34a and the communication device 70b has been determined as the recommended combination.

[0156] The vehicle control unit 31 determines a recommended wireless power value for the vehicle communication unit 34a based on the result of the trial communication, and stores the value in the storage unit 32 (step S304). This determination process corresponds to steps S214 to S216 in the flowchart shown in FIG. 12.

[0157] If it is determined in step S302 that the trial response signal substantially includes the past recommended communication information, the vehicle control unit 31 determines the recommended communication combination information and the recommended wireless power value to be the same as the past recommended communication information (step S305). In this case, the processes of steps S303 and S304 are skipped. Here, as in the above, it is assumed that the combination of the vehicle communication unit 34a and the communication device 70b is determined as the recommended combination.

[0158] The bogie control unit 31 causes the bogie communication unit 34a to perform SEMI E84 communication with the communication device 70a via the wireless communication path to the communication device 70b based on the recommended combination and wireless power value (step S306). Specifically, this signal transmission and reception is performed by issuing SEMI E84 PI / O commands or the like via wireless communication. This allows the bogie control unit 31 to obtain information necessary for interlock control.

[0159] In the process of the above-described SEMI E84 communication, the vehicle communication unit 34a transmits a command signal to the communication device 70b, and the communication device 70b transmits a command response signal to the vehicle communication unit 34a. Similar to the frame of the trial response signal (FIG. 8) described above, the frame of the command response signal describes the RSSI value at the time when the communication device 70b received the frame of the command signal from the vehicle communication unit 34a.

[0160] During the SEMI E84 communication, the vehicle control unit 31 monitors the RSSI value of the communication device 70b included in the command response signal (step S307). If the monitored RSSI value is equal to or greater than a predetermined threshold, the vehicle control unit 31 updates the recommended wireless power value to an appropriately lower value and changes the wireless transmission power value of the vehicle communication unit 34a according to the updated recommended value. This makes it possible to achieve energy conservation and suppress interference with nearby close-proximity wireless communication even after the start of SEMI E84 communication.

[0161] When the necessary processing is completed, the bogie control unit 31 determines whether the recommended communication information, which is a set of recommended communication combination information and recommended wireless power value, is a newly obtained value or a value that has been updated after being determined based on past recommended communication information (step S308). If the processing of steps S303 and S304 has been performed, the recommended communication information will be a new value. If the processing of step S305 has been performed, or if the recommended wireless power value has been changed as described in step S307, the recommended communication information will be an updated value.

[0162] If the determination result in step S308 is positive, the vehicle control unit 31 causes the vehicle communication unit 34a to transmit the above-mentioned recommended communication combination information and the recommended wireless power value to the communication device 70b (step S309). The communication device 70b stores the received recommended communication combination information and the recommended wireless power value in the storage unit 72.

[0163] The recommended communication combination information and recommended wireless power values ​​are transmitted from communication device 70b to the other communication devices 70 that are part of the same group. This communication uses the second communication unit 74. Each communication device 70 stores the received trial communication results in the storage unit 72. Therefore, the recommended communication combination information and recommended wireless power values ​​based on the trial communication results are shared among all communication devices 70 that belong to the same group and are linked to each other.

[0164] If the determination result in step S308 is negative, the stored contents of the storage unit 72 remain up to date, and therefore the process of step S309 is skipped.

[0165] The frame of the trial communication result notification signal transmitted from the carriage communication unit 34a to the communication device 70b in step S309 is shown in Fig. 14. As shown in Fig. 14, the frame of the trial communication result notification signal includes the final destination communication device ID, transport carriage information, carriage position and orientation information, recommended communication combination information, and recommended wireless power value.

[0166] The "final destination communication device ID," "transportation vehicle information," and "vehicle position and attitude information" contain the values ​​of the "final destination communication device ID," "transportation vehicle information," and "vehicle position and attitude information" described in Figure 4 as they are.

[0167] In the "recommended communication combination information", a value specifying which combination of the two vehicle communication units 34 and the four communication devices 70 determined in step S303 is recommended is described.

[0168] The "recommended wireless power value" describes the transmission power determined in step S304 that is recommended when the vehicle communication unit 34 performs wireless communication.

[0169] Next, the contents stored in the storage unit 72 regarding the trial communication results will be described with reference to Fig. 15. Fig. 15 is a diagram showing the contents stored in the storage unit 72 in a schematic table format.

[0170] Each of the communication devices 70 stores the recommended communication combination information and the recommended wireless power value based on the trial communication result in the storage unit 72 in association with a combination of the final destination communication device ID, the transport vehicle information, and the vehicle position and attitude information, as shown in Fig. 15. Since the recommended communication information is stored on the communication device 70 side, the configuration is such that inconsistencies in information are unlikely to occur between the multiple transport vehicles 30a, 30b.

[0171] In step S309 of Fig. 13, when the communication device 70 receives recommended communication combination information and recommended wireless power values ​​from the vehicle communication unit 34 for a new combination of final destination communication device ID, transport vehicle information, and vehicle position and orientation information, the communication device 70 stores the values ​​described in the frame shown in Fig. 14 in the form of adding a row to the table of Fig. 15. If recommended communication combination information and recommended wireless power values ​​have already been stored corresponding to the combination of final destination communication device ID, transport vehicle information, and vehicle position and orientation information, the recommended communication combination information and transmission power value of that row are updated based on the newly received information.

[0172] When trial communication is subsequently performed, the communication device 70 receives a trial signal shown in step S101 of FIG. 9 from the vehicle communication unit 34. When generating a frame of the trial response signal, the control unit 71 of the communication device 70 searches the stored contents shown in FIG. 15 for a row that matches the combination of the final destination communication device ID, transport vehicle information, and vehicle position and orientation information included in the received frame (see FIG. 4). If a matching row is found, the communication device 70 writes the recommended communication combination information and the transmission power value included in that row in the “past recommended communication combination information” and “past recommended wireless power value” fields. The communication device 70 transmits the generated frame including the past recommended communication information to the vehicle communication unit 34 as a trial response signal. When the vehicle communication unit 34 receives the trial response signal in step S102 of FIG. 9, the vehicle control unit 31 detects the presence of past recommended communication information in step S103 and terminates the trial communication.

[0173] As described above, the contents stored in the storage unit 72 are shared by all communication devices 70 that are part of the same group and are linked to one another. Therefore, even if the cart communication unit 34 performs trial communication with any of the four communication devices 70 as its direct communication partner, it can appropriately obtain past recommended communication information that meets the conditions.

[0174] In this embodiment, the transport vehicle information only indicates the type of the transport vehicle 30a, 30b, and does not include an ID that uniquely identifies the transport vehicle 30a, 30b. For example, consider a case where both the two transport vehicles 30a, 30b are ceiling-suspended grid-type transport vehicles. In this case, the values ​​of the transport vehicle information can be considered to be the same. That is, as long as the final destination communication device ID and the transport vehicle position and orientation information match, the same recommended communication information is applied to the transport vehicles 30a and 30b. Therefore, as long as the transport vehicle 30a uses the same load port 60a as the transfer destination or the transfer source and stops at the same position and orientation relative to the load port 60a, the transport vehicle 30b can acquire and use, for example, recommended communication information based on trial communication previously performed by the transport vehicle 30a.

[0175] As described above, the transport system 1 of this embodiment includes a plurality of transport vehicles 30 and a plurality of communication devices 70. The transport vehicle 30 transports a FOUP 95. The plurality of communication devices 70a to 70d are connected one-to-one to each of a plurality of pieces of equipment between which the FOUP 95 is transferred and loaded to and from the transport vehicle 30. The plurality of communication devices 70a to 70d can communicate with each other. In this transport system 1, the transport vehicle 30 performs wireless communication with the load port 60 to transfer the FOUP 95 using the following method. The wireless communication method of this embodiment includes a first step and a second step. In the first step (step S101 in FIG. 9 ), a trial signal is wirelessly transmitted to the plurality of communication devices 70a to 70d using the vehicle communication units 34a and 34b provided on a specific transport vehicle 30a among the plurality of transport vehicles 30, prior to communication associated with the transfer of the FOUP 95. In the second step (step S306 in FIG. 13), based on the communication status regarding the transmission performed to the multiple communication devices 70a to 70d in the first step (specifically, the RSSI values ​​obtained in steps S106 and S107 in FIG. 9), either the cart communication unit 34a or 34b transmits and receives communication data to and from a specific communication device (via one of 70a to 70d) among the multiple communication devices 70 via a communication path, at least a portion of which is a wireless communication path.

[0176] This makes it possible to efficiently determine the communication path in the second step based on the communication in the first step in a configuration where wireless communication is made redundant.

[0177] In this embodiment, in the first step (step S101 in FIG. 9 ), the trial signal wirelessly transmitted to the plurality of communication devices 70a to 70d is designated as a final destination for a specific communication device (e.g., communication device 70a) among the plurality of communication devices 70a to 70d. In the second step (step S306 in FIG. 13 ), the communication device 70a, which is the final destination, may receive a signal from the carriage communication unit 34a via a communication path that passes through another communication device (e.g., communication device 70b) among the plurality of communication devices 70a to 70d. The wireless communication method of this embodiment includes a third step and a fourth step. In the third step (step S309), as shown in FIG. 15 , the position information of the specific transport carriage 30a in the first step and the identification information of the other communication device 70b that was present on the communication path in the second step are stored in the storage unit 72 of the communication device 70 in an associated form. 15, the identification information of the other communication device 70b is substantially included in the recommended communication combination information. In a fourth step (steps S305 and S306 in a situation where the flow in FIG. 13 is restarted after the flow has ended with the processing of step S309), the vehicle communication unit 34a transmits a signal to the other communication device 70b, with the specific communication device 70a as the final destination, based on the information stored in the third step.

[0178] As a result, in the third step, the communication path used in the second step can be stored in association with the position of the transporting vehicle 30a. In the fourth step, the communication path can be determined quickly using the information stored in the third step. Therefore, this method is suitable for cases where it is desirable to change the communication path from the transporting vehicle communication unit 34a to the final destination communication device 70a depending on the position of the transporting vehicle 30a.

[0179] In the third step of this embodiment, as shown in Figure 15, the posture information of a specific transport cart 30a in the first step and the identification information of another communication device 70b that was present on the communication path in the second step are stored in a corresponding manner in the memory unit 72 of the communication device 70.

[0180] As a result, in the third step, the communication path used in the second step can be stored in association with the position of the transport vehicle 30a as well as the posture of the transport vehicle 30a. This is therefore suitable for cases where it is desirable to change the communication path from the transport vehicle communication unit 34a to the final destination communication device 70a depending on the posture of the transport vehicle 30a.

[0181] In this embodiment, the specific transport vehicle 30a is equipped with multiple antennas 39a, 39b. In the third step, as shown in Fig. 15 , the position information of the specific transport vehicle 30a in the first step, information specifying the antenna 39a used for wireless communication in the second step, and information specifying another communication device 70b that was present on the communication path in the second step are stored in a corresponding form in the storage unit 72 of the communication device 70. In Fig. 15 , the number of the transport vehicle communication unit 34a is included in the recommended communication combination information, which is substantially the same as specifying the antenna 39a.

[0182] As a result, in the third step, the communication path used in the second step can be appropriately stored in a form that substantially includes the position of the antenna 39a used by the bogie communication unit 34a for wireless communication.

[0183] The wireless communication method of this embodiment includes a fifth step, a sixth step, a seventh step, an eighth step, and a ninth step. In the fifth step (step S101 in FIG. 9 ), a trial signal is wirelessly transmitted to the plurality of communication devices 70a-70d using the carriage communication units 34a, 34b provided on a specific one of the plurality of transport carriages 30, prior to communication associated with the transfer of the FOUP 95. The trial signal includes final destination communication device information. The final destination communication device information is information that specifies a specific communication device among the plurality of communication devices as the final destination of the trial signal. In the sixth step (steps S106, S107 in FIG. 9 ), preliminary result information is stored in the storage unit 32. The preliminary result information includes the communication status of the transmission performed to the plurality of communication devices 70a-70d in the fifth step (specifically, the RSSI values ​​measured by the carriage communication units 34a, 34b). In addition, the preliminary result information includes preliminary transmission response information indicating the responses of the communication devices 70a to 70d to the transmission (specifically, the contents of the communication device-side RSSI values ​​shown in FIG. 8 in the trial response frame, etc.). In a seventh step (step S306 in FIG. 13), the carriage communication unit 34a provided in the transport carriage 30a transmits and receives communication data to and from a specific communication device 70a designated as the final destination among the multiple communication devices 70a to 70d via a communication path, at least a portion of which is a wireless communication path. In this transmission and reception, whether any other communication device among the multiple communication devices 70a to 70d will relay the transmission and reception of the communication data, and if so, which communication device (e.g., communication device 70b) will relay the transmission and reception of the communication data, follows the recommended communication combination information determined in step S303 based on the preliminary result information stored in the sixth step. In an eighth step (step S309), recommended communication information (specifically, recommended communication combination information and recommended transmission power values) based on the preliminary result information of the sixth step is stored in the storage unit 72 in association with the final destination communication device information and the transport vehicle information of the fifth step. The transport vehicle information is information relating to the transport vehicle 30a that transmitted the trial signal in the fifth step.In the ninth step (steps S305 and S306 in a situation where the flow in FIG. 13 is restarted after the flow has ended with the processing of step S309), the carriage communication unit 34a provided in the transport carriage 30a transmits and receives communication data to and from a specific communication device 70a designated as a final destination among the plurality of communication devices 70a to 70d via a communication path at least a part of which is a wireless communication path. In this transmission and reception, whether or not any other communication device among the plurality of communication devices 70a to 70d will relay the transmission and reception of the communication data, and if so, which communication device (e.g., communication device 70b) will relay the transmission and reception of the communication data, is determined based on the recommended communication combination information stored in the eighth step.

[0184] As a result, in a configuration in which wireless communication is redundant, preliminary result information, which is the result of the communication performed in the preliminary step 5, can be acquired in the sixth step. In the seventh step, communication can be performed with the communication device 70a, which is the final destination, via a communication path appropriately determined based on the preliminary result information acquired in the sixth step. By storing recommended communication information based on the preliminary result information acquired in the sixth step in the eighth step, the communication path can be efficiently determined using the stored information in the communication in the ninth step.

[0185] In this embodiment, the transmission of the trial signal in the fifth step is performed using multiple wireless communication channels, and the transmission and reception of communication data in the seventh and ninth steps is performed using multiple channels.

[0186] As a result, in a situation where wireless communication is possible over multiple channels, the preliminary communication is also performed over multiple channels, making it possible to appropriately determine the communication path.

[0187] In this embodiment, the recommended communication combination information of the eighth step is stored in the memory unit 72 in a form corresponding to information specifying the type of transport vehicle 30a, information specifying the position of the transport vehicle 30a (position information of the transport vehicle 30a), and information specifying the posture of the transport vehicle 30a (posture information of the transport vehicle 30a), as shown in Figure 15.

[0188] As a result, in the ninth step, a communication route can be efficiently determined in accordance with important conditions when selecting a communication route.

[0189] In this embodiment, the recommended communication combination information, which is one type of recommended communication information stored in step 8, includes information identifying a vehicle communication unit (e.g., the vehicle communication unit 34a) that is recommended to transmit and receive communication data. The recommended communication combination information also includes information identifying another communication device (e.g., the communication device 70b) among the multiple communication devices 70a to 70d that is recommended to relay communication between the vehicle communication unit 34a and the final destination communication device 70a. In addition, the recommended wireless power value, which is one type of recommended communication information, includes the wireless transmission power that is recommended when the vehicle communication unit 34a transmits communication data.

[0190] This allows appropriate communication to be carried out in the ninth step.

[0191] In this embodiment, the storage unit 72 included in each of the plurality of communication devices 70a to 70d is capable of storing the recommended communication information in step 8. The plurality of communication devices 70a to 70d share the recommended communication information stored in the storage unit 72 through communication between the communication devices 70a to 70d.

[0192] As a result, in the ninth step, the recommended communication information stored in the eighth step can be acquired from any of the communication devices 70a to 70d, thereby facilitating acquisition of information necessary for determining a communication route in the ninth step.

[0193] In this embodiment, the preliminary result information stored in the storage unit 32 in the sixth step includes a communication state regarding the transmission of the trial communication signal in the fifth step. This communication state includes the RSSI value when the vehicle communication units 34a, 34b receive a signal from the communication devices 70a-70d, and the RSSI value when the communication devices 70a-70d receive a signal from the vehicle communication units 34a, 34b. In the seventh step, whether any other communication device among the plurality of communication devices 70a-70d will relay the transmission and reception of communication data, and if so, which communication device (e.g., communication device 70b) will perform the relay, is determined based on the result of comparing the RSSI values ​​regarding the plurality of communication devices 70a-70d.

[0194] This allows the communication path to be appropriately determined in the seventh step based on the RSSI value.

[0195] In this embodiment, if a communication device is discovered in which both of the two RSSI values ​​are above the threshold value while performing the fifth and sixth steps for each of the multiple communication devices 70a to 70d, the two RSSI values ​​for that communication device are stored in the memory unit 32, and then the fifth and sixth steps are terminated midway.

[0196] This allows the time required for trial communication to be substantially reduced.

[0197] In this embodiment, the transporting vehicle 30a is capable of transferring the FOUP 95 while stopped at a position selected from a plurality of positions relative to the load port 60a. In the eighth step, the stopping position of the transporting vehicle 30a is stored in the memory unit 72 as information specifying the position of the transporting vehicle 30a (position information of the transporting vehicle 30a).

[0198] As a result, in the ninth step, the communication path can be determined efficiently, taking into account the stopping position of the transport vehicle 30a relative to the load port 60a, and communication can be performed.

[0199] In this embodiment, the transport vehicle 30a is capable of transferring the FOUP 95 while stopped in a posture selected from a plurality of postures relative to the load port 60a. In the eighth step, the stopping posture of the transport vehicle 30a is stored in 72 as information specifying the posture of the transport vehicle 30a (posture information of the transport vehicle 30a).

[0200] As a result, in the ninth step, the communication path can be determined efficiently, taking into account the stopping posture of the transport vehicle 30a relative to the load port 60a, and communication can be performed.

[0201] In this embodiment, the transport vehicles 30a, 30b move in a first direction D1 and a second direction D2 on a grid-shaped track 90. ​​The second direction D2 is perpendicular to the first direction D1. The transport vehicles 30a, 30b transfer FOUPs 95 to and from load ports 60a to 60d installed below the track 90.

[0202] This allows the communication route to be determined efficiently based on prior communication in a transport system in which the transport vehicles 30a and 30b have a wide variety of stopping positions.

[0203] In this embodiment, the plurality of communication devices 70 a to 70 d are connected to one another by cables 84 .

[0204] This allows stable communication between the plurality of communication devices 70a to 70d.

[0205] Next, a second embodiment will be described. In the description of this embodiment, the same or similar components as those in the previous embodiment are denoted by the same reference numerals in the drawings, and the description thereof may be omitted.

[0206] In the first embodiment described above, recommended communication combination information and recommended transmission power values ​​based on the results of trial communications are stored in the storage units 72 of the communication devices 70a to 70d. In contrast, in this embodiment, the recommended communication combination information and recommended transmission power values ​​are stored in the storage unit 12 of the control server 10 shown in Fig. 2. Because the recommended communication information is stored in the control server 10, inconsistencies in information are less likely to occur between the multiple transport vehicles 30a, 30b.

[0207] In this embodiment, information corresponding to the table shown in Fig. 15 is handled by the control server 10, not the communication device 70. Therefore, there is no need to perform trial communication between the cart communication unit 34 and the communication device 70 in order to obtain information based on the results of past trial communication (i.e., past recommended communication information).

[0208] The transport vehicles 30a, 30b transport the FOUP 95 from one processing device 50 to another processing device 50 in accordance with a transport command from the control server 10. In this embodiment, before transmitting the transport command to the transport vehicle 30, the control unit 11 of the control server 10 searches the contents stored in the memory unit 12 for recommended communication information corresponding to a combination of the final destination communication device ID, transport vehicle information, and vehicle position and orientation information. If corresponding recommended communication information is obtained, the control unit 11 adds the recommended communication information to the transport command as past recommended communication information. Therefore, the transport vehicle 30 can acquire past recommended communication information at the same time as receiving the transport command from the control server 10 via the wireless communication device 20.

[0209] Hereinafter, the trial communication in the second embodiment and the subsequent SEMI E84 communication for interlock control will be described with reference to the flowchart of FIG.

[0210] When the transport vehicle 30a stops at the position and attitude specified by the transport command, the vehicle control unit 31 determines whether past recommended communication information has been given together with the transport command (step S401).

[0211] If past recommended communication information is not provided, the vehicle control unit 31 performs trial communication (step S402). This trial communication is substantially similar to the flows in Figures 9 and 10. However, in this embodiment, the response signal returned from the communication device 70 to the vehicle communication unit 34 in response to the trial communication does not include past recommended communication information. Therefore, the determination in step S103 in Figure 9 is omitted in this embodiment.

[0212] The processing in steps S403 to S408 is substantially the same as the processing in steps S303 to S308 in FIG. 13, and therefore a description thereof will be omitted.

[0213] If the determination result in step S408 is positive, the vehicle control unit 31 causes the vehicle communication unit 34a to transmit the above-mentioned recommended communication combination information and recommended wireless power value to the control server 10 via the wireless communication device 20 (step S409). The control unit 11 of the control server 10 stores the received trial communication result in the storage unit 12.

[0214] As described above, the transport system 1 of this embodiment includes the control server 10. The control server 10 controls the multiple transport vehicles 30. In an eighth step (step S409), the storage unit 12 included in the control server 10 stores recommended communication information (specifically, recommended communication combination information and recommended transmission power values).

[0215] This allows the recommended communication information commonly applied to a plurality of transporting vehicles 30 to be collected and stored in the control server 10. This makes it possible to prevent inconsistencies in the information.

[0216] Two preferred embodiments of the present invention have been described above, but the above configurations can be modified, for example, as follows. Each modification may be made alone, or multiple modifications may be made in any combination.

[0217] The recommended communication combination information and the recommended wireless power value based on the result of the trial communication do not have to be associated with the stopped posture of the transport vehicle 30a.

[0218] The determination of the recommended radio power value based on the result of the trial communication may be omitted.

[0219] An index other than the RSSI value may be used as an index indicating communication quality. For example, a packet error rate may be used instead of the RSSI value.

[0220] The number of carriage communication units 34 provided on one transport carriage 30a is not limited to two, but may be, for example, three or more.

[0221] It is also possible to configure the transporting carriage 30a so that one carriage communication unit 34 is provided, multiple antennas 39 are connected to the carriage communication unit 34, and an antenna 39 selected from the multiple antennas 39 is used for wireless communication. In this case, the recommended communication combination information is a combination of information specifying the antenna 39 to be used, which is expected to provide the best wireless communication, and information specifying the communication device 70 to which the signal is to be transmitted.

[0222] The stopping positions and postures that the transport vehicle 30 can take relative to the load port 60 are not limited to those shown in Figures 5 to 7. For example, the transport vehicle 30 may be configured so that the lateral mechanism can be extended in a direction diagonally 45° relative to both the first track 91 and the second track 92. In this case, the transport vehicle 30 can stop at a position diagonally adjacent to the load port 60 and transfer a FOUP to and from the load port 60.

[0223] In the first embodiment, the recommended communication information based on the results of the trial communication does not need to be shared among a plurality of communication devices 70 .

[0224] In the first embodiment, as shown in FIG. 15 , after the recommended communication information is stored in the storage unit 72 of the communication device 70, the recommended communication information may be deleted after a predetermined period of time has elapsed. This prevents the recommended communication information from becoming excessively outdated. Furthermore, if good communication is not obtained as a result of the transport vehicle 30 performing communication in accordance with the recommended communication information, the recommended communication information may be deleted from the storage unit 72. Possible cases in which good communication is not obtained include when the command response signal from the communication device 70 is delayed in response to a command signal from the vehicle communication unit 34, or when the error rate increases. If the recommended communication information is deleted, trial communication is performed again thereafter, and new recommended communication information is stored in the storage unit 72. Similarly, in the second embodiment, the recommended communication information stored in the storage unit 12 of the control server 10 may be deleted.

[0225] In the above embodiment, in steps S214 to S216 of Fig. 12, the recommended wireless power value is changed based on the value of the second comparison variable. Alternatively, the recommended wireless power value may be changed based on the values ​​of both the first comparison variable and the second comparison variable. For the same purpose, in step S307 of Fig. 13, the RSSI value of the vehicle communication unit 34a may be monitored in addition to the RSSI value of the communication device 70a, and the recommended wireless power values ​​of the communication device 70a and the vehicle communication unit 34a may be changed independently.

[0226] Furthermore, when another communication device 70b relays communication to the final destination communication device 70a, the communication can be relayed directly or via another communication device (e.g., communication device 70c). For example, in RS485 communication, when both communication devices 70a and 70b are operating as slave devices, the communication is relayed via the communication device 70c operating as the master device.

[0227] REFERENCE SIGNS LIST 1 Transport system 5 Wireless communication system 30 Transport vehicle 32 Storage unit 34 Vehicle communication unit 60 Load port (facility) 70 Communication device 72 Storage unit

Claims

1. A wireless communication method for a transport system comprising a plurality of transport vehicles for transporting transported objects, and a plurality of communication devices connected one-to-one to a plurality of pieces of equipment between which the transported objects are transferred and which are connected to the transport vehicle, wherein the plurality of communication devices are capable of communicating with each other, in which the transport vehicle performs wireless communication with the equipment to transfer the transported objects, the wireless communication method comprising: a first step of using a vehicle communication unit provided in a specific transport vehicle among the plurality of transport vehicles to wirelessly transmit signals to the plurality of communication devices prior to communication accompanying the transfer of the transported objects; and a second step of using the vehicle communication unit to transmit and receive communication data between the specific communication device among the plurality of communication devices and the specific communication device among the plurality of communication devices via a communication path, at least a portion of which is a wireless communication path, based on the communication state regarding the transmission performed to the multiple communication devices in the first step.

2. A wireless communication method as claimed in claim 1, wherein in the first step, the signal wirelessly transmitted to the plurality of communication devices is designated with the specific communication device among the plurality of communication devices as the final destination; and in the second step, the specific communication device that is the final destination receives the signal from the carriage communication unit over a communication path that passes through another communication device among the plurality of communication devices; and the wireless communication method comprises: a third step of correlating and storing position information of the specific transport carriage in the first step with identification information of the other communication device that intervened on the communication path in the second step; and a fourth step of, based on the information stored in the third step, the carriage communication unit transmits the communication data to the other communication device, with the specific communication device as the final destination.

3. A wireless communication method as described in claim 2, characterized in that in the third step, the posture information of the specific transport vehicle in the first step and the identification information of the other communication device that was present on the communication path in the second step are stored in association with each other.

4. A wireless communication method according to claim 2, wherein the specific transport vehicle is equipped with a plurality of antennas, and in the third step, the position information of the specific transport vehicle in the first step, information specifying the antenna among the plurality of antennas that performed communication in the second step, and identification information of the other communication device that was present on the communication path in the second step are stored in association with each other.

5. A wireless communication method for a transport system comprising a plurality of transport vehicles for transporting transported objects, and a plurality of communication devices connected one-to-one to a plurality of pieces of equipment between which the transported objects are transferred and which are connected to the transport vehicle, wherein the plurality of communication devices are capable of communicating with each other, wherein the transport vehicle performs wireless communication with the equipment to transfer the transported objects, the method comprising: a fifth step of wirelessly transmitting a signal including final destination communication device information that designates a specific communication device among the plurality of communication devices as a final destination, to the plurality of communication devices, using a vehicle communication unit provided in a specific transport vehicle among the plurality of transport vehicles, prior to communication accompanying the transfer of the transported objects; and a sixth step of storing advance result information that is at least one of the communication status of the transmission made to the plurality of communication devices in the fifth step and advance transmission response information that indicates the response of the communication device to the transmission. a seventh step in which a carriage communication unit provided in the transport carriage transmits and receives communication data to and from a specific communication device designated as the final destination among the plurality of communication devices via a communication path at least a part of which is a wireless communication path, and whether or not any other communication device among the plurality of communication devices will relay the transmission and reception of the communication data, and if so, which communication device will perform the relay, is determined based on the preliminary result information stored in the sixth step; an eighth step in which the preliminary result information of the sixth step or information based thereon is stored as recommended communication information in association with the final destination communication device information of the fifth step and transport carriage information which is information related to the transport carriage that transmitted the signal in the fifth step; a ninth step in which a carriage communication unit provided on the transport carriage transmits and receives communication data to and from a specific communication device among the plurality of communication devices that is designated as the final destination via a communication path, at least a portion of which is a wireless communication path, and whether any other communication device among the plurality of communication devices will relay the transmission and reception of the communication data, and if so, which communication device will relay it, is determined based on the recommended communication information stored in the eighth step.

6. A wireless communication method according to claim 5, wherein the transmission of the signal in the fifth step is carried out using a plurality of wireless communication channels, and the transmission and reception of the communication data in the seventh and ninth steps is carried out using the plurality of channels.

7. A wireless communication method as described in claim 5, characterized in that in the eighth step, the recommended communication information is stored in association with at least one of information specifying the type of the transport vehicle, information specifying the position of the transport vehicle, and information specifying the attitude of the transport vehicle.

8. A wireless communication method as described in claim 5, characterized in that in the eighth step, the recommended communication information includes at least one of information identifying the vehicle communication unit that is recommended to send and receive the communication data, information identifying a wireless communication antenna that is recommended to be used to send and receive the communication data, information identifying another communication device among the plurality of communication devices that is recommended to relay communication between the vehicle communication unit and the communication device specified as the final destination, and wireless transmission power that is recommended when the vehicle communication unit sends the communication data.

9. A wireless communication method as described in claim 5, wherein a memory unit provided in each of the plurality of communication devices is capable of storing the recommended communication information in the eighth step, and the plurality of communication devices share the recommended communication information stored in the memory unit through communication between the communication devices.

10. A wireless communication method as described in claim 5, wherein the preliminary result information stored in the sixth step includes a communication status regarding the transmission of the signal in the fifth step, and the communication status includes a received radio wave strength indicating the radio wave strength when the vehicle communication unit receives a signal from the communication device, or the radio wave strength when the communication device receives a signal from the vehicle communication unit, and wherein in the seventh step, whether any other communication device among the plurality of communication devices will relay the transmission and reception of the communication data, and if so, which communication device will perform the relay, is determined based on the result of comparing the received radio wave strengths for the plurality of communication devices.

11. A wireless communication method as described in claim 5, wherein the preliminary result information stored in the sixth step includes a communication status regarding the transmission of the signal in the fifth step, and the communication status includes a received radio wave strength indicating the radio wave strength when the vehicle communication unit receives a signal from the communication device, or the radio wave strength when the communication device receives a signal from the vehicle communication unit, and if a communication device whose received radio wave strength is above a threshold is discovered while performing the fifth step and the sixth step for each of the plurality of communication devices, the preliminary result information for that communication device is stored, and then the fifth step and the sixth step are terminated.

12. A wireless communication method according to claim 5, wherein the transport system includes a control server that controls a plurality of the transport vehicles, and in the eighth step, the recommended communication information is stored in a memory unit included in the control server.

13. A wireless communication method according to claim 7, wherein the transport vehicle is capable of transferring the transported object while stopped at a position selected from a plurality of positions relative to the facility, and wherein in the eighth step, the stopping position of the transport vehicle is stored as information specifying the position of the specific transport vehicle.

14. A wireless communication method according to claim 7, wherein the transport vehicle is capable of transferring the transported object while stopped in a posture selected from a plurality of postures relative to the equipment, and wherein in the eighth step, the stopped posture of the transport vehicle is stored as information specifying the posture of the specific transport vehicle.

15. A wireless communication method according to any one of claims 1 to 14, characterized in that the transport vehicle moves on a track configured in a lattice pattern in a first direction and a second direction perpendicular to the first direction, and transfers the transported object to the equipment installed below the track.

16. A wireless communication method according to any one of claims 1 to 14, characterized in that the plurality of communication devices are connected to each other by cables.

17. A wireless communication system comprising: a plurality of transport vehicles for transporting transported objects; a vehicle communication unit disposed on each of the plurality of transport vehicles; and a plurality of communication devices connected one-to-one to each of a plurality of pieces of equipment between which the transported objects are transferred and which are connected to the transport vehicles, wherein the plurality of communication devices are capable of communicating with each other; the vehicle communication unit disposed on a specific transport vehicle among the plurality of transport vehicles that transfers the transported objects wirelessly transmits signals to the plurality of communication devices prior to communication associated with the transfer of the transported objects; and based on the communication status of the transmission made to the plurality of communication devices, the vehicle communication unit transmits and receives communication data to and from a specific communication device among the plurality of communication devices via a communication path, at least a portion of which is a wireless communication path.

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