Wireless communication receiving method and communication system using the same

Abstract

The present invention provides a wireless communication receiving method and a communication system using the method. The communication system includes a communication management unit, an access point, and a plurality of traveling vehicles. The access point is connected to the communication management unit. Each traveling vehicle has a wireless communication unit. The communication system performs wireless polling communication between the communication management unit and the plurality of traveling vehicles via the access point every polling period (T). In the communication system, in order to accept a newly-built traveling vehicle as a wireless communication object, a process including a wireless communication party addition process is performed. In the wireless communication party addition process, within the polling period (T), after the wireless polling communication between the communication management unit and the plurality of traveling vehicles is completed and until the end of the period in which the wireless polling communication can be performed, that is, during the idle time, a connection sequencing for enabling the communication system to accept the newly-built traveling vehicle is performed.

Description

Technical Field

[0001] The present invention mainly relates to wireless communication with a traveling vehicle as a target, and more particularly to a method for allowing a wireless communication system to accept a newly built traveling vehicle as a wireless communication target. Background Art

[0002] Conventionally, for example, in an automatic transport system, a communication system is used that performs wireless polling communication (hereinafter referred to as wireless polling communication) between a controller and a plurality of traveling vehicles under its management. Patent Document 1 discloses such an automatic transport system.

[0003] The automatic transport system (transportation vehicle system) of Patent Document 1 is configured such that a controller and a vehicle controller provided in a vehicle perform wireless polling-based communication.

[0004] Patent Document 1: Japanese Patent No. 4360344 Summary of the invention

[0005] Problem that the invention aims to solve

[0006] In an automatic transport system, a newly built trolley is sometimes added after the fact for the purpose of enhancing transport force, replacing a spare trolley in case of failure, etc. When a newly built trolley is added to a transport trolley system such as Patent Document 1, it is necessary to make the communication system recognize the newly built trolley as the object of wireless polling communication.

[0007] The general procedure for adding a newly created vehicle as a target of wireless polling communication can be, for example, as follows. The communication system continuously sends a beacon for detecting the vehicle to be added at a predetermined time interval. When the vehicle receives the beacon, it obtains information related to wireless communication from the received beacon and performs settings for wireless communication.

[0008] It is also possible that the vehicle side continuously transmits a beacon requesting the addition of the vehicle itself at a predetermined time interval. In this case, when the communication system receives the beacon, it obtains information related to wireless communication from the received beacon and performs settings for wireless communication.

[0009] In the transport trolley system of Patent Document 1, periodic wireless polling communication is almost continuously performed between the controller and the trolley controller during operation. Therefore, if beacons are continuously sent as described above to add a newly built trolley, wireless polling communication may be hindered, thereby damaging the stability of trolley control.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the influence on the wireless polling communication already being performed and to allow the communication system to accept a newly-built vehicle as a wireless communication target.

[0011] Means used to solve the problem and their effects

[0012] The problems to be solved by the present invention are as described above. Next, means for solving the problems and their effects will be described.

[0013] According to the first aspect of the present invention, a wireless communication receiving method having the following structure is provided. That is, the wireless communication receiving method is a method for causing a communication system to accept a newly-built vehicle as a wireless communication object. The communication system comprises a controller, an access point, and a plurality of vehicles. The access point is connected to the controller. The plurality of vehicles respectively have a wireless communication unit. The communication system performs wireless polling communication between the controller and the plurality of vehicles via the access point at intervals of a predetermined polling cycle. The wireless communication receiving method performs a process including a wireless communication party addition process. In the wireless communication party addition process, within the polling cycle, after the wireless polling communication between the controller and the plurality of vehicles is completed and until the end of a period during which wireless polling communication is possible, that is, during idle time, a connection sequencing accompanied by wireless communication is performed, and the connection sequencing is used to cause the communication system to accept the newly-built vehicle.

[0014] In this way, by executing the connection sequence of the newly-added vehicle during the idle time when the wireless polling communication is not performed, the influence of the connection sequence on the wireless polling communication can be eliminated. In addition, the communication system can accept the newly-added vehicle through a simple operation.

[0015] In the wireless communication receiving method described above, the following configuration is preferred. That is, in the wireless communication receiving method, a process including a connection determination step of determining whether the idle time is longer than a prescribed time is performed. If it is determined in the connection determination step that the idle time is longer than a prescribed time, the wireless communication party adding step is performed. If it is determined in the connection determination step that the idle time is shorter than a prescribed time, the wireless communication party adding step is not performed.

[0016] This makes it possible to reliably prevent the wireless polling communication from being hindered by the execution of the connection sequence.

[0017] In the wireless communication receiving method, preferably, in the wireless communication party adding step, the controller wirelessly transmits a frame for starting the connection sequencing via the access point during the idle time.

[0018] This eliminates the need to input information for wireless communication (eg, identification information of access points) into a newly built vehicle in advance, thereby preventing input errors from occurring and reducing the operator's workload.

[0019] In the wireless communication receiving method, preferably, in the wireless communication party adding step, the controller transmits a frame for starting the connection sequencing based on an acceptance command input by an operator.

[0020] As a result, frames are not transmitted when there is no operation by the operator, and thus it is possible to avoid unnecessary transmission when there is no new traveling vehicle.

[0021] In the wireless communication receiving method, preferably, in the wireless communication party adding step, the newly-built vehicle wirelessly transmits a frame for starting the connection sequencing during the idle time.

[0022] This eliminates the need to input information for wireless communication (eg, identification information of a newly-built vehicle) into an access point or a controller in advance, thereby preventing input errors from occurring and reducing the workload of operators.

[0023] In the wireless communication receiving method, the following configuration is preferred. That is, in the wireless communication receiving method, the newly-built vehicle performs a process including an idle time estimation process. In the idle time estimation process, the newly-built vehicle monitors the wireless polling communication between the controller and the plurality of vehicles, and estimates the idle time.

[0024] This allows the newly built vehicle to estimate the idle time when wireless polling communication is not performed. Therefore, the newly built vehicle can send a frame for joining the wireless communication during the time period when wireless polling communication is not performed. That is, it is possible to avoid the transmission of frames that hinder wireless polling communication.

[0025] According to a second aspect of the present invention, a communication system having the following structure is provided. That is, the communication system comprises a controller, an access point, and a plurality of traveling vehicles. The access point is connected to the controller. The plurality of traveling vehicles respectively have a wireless communication unit. In the communication system, the controller performs wireless polling communication with a predetermined number of traveling vehicles under its jurisdiction via the access point at intervals of a predetermined polling cycle. During the polling cycle, during the time after the wireless polling communication between the controller and the predetermined number of traveling vehicles via the access point is completed and until the end of the polling cycle, that is, during the idle time, a connection sequencing accompanied by wireless communication is performed, and the connection sequencing is used to accept wireless communication with a newly-created traveling vehicle that is not included in the plurality of traveling vehicles that are the objects of the wireless polling communication.

[0026] In this way, by executing the connection sequence of the newly-added vehicle during the idle time when the wireless polling communication is not performed, the influence of the connection sequence on the wireless polling communication can be eliminated. In addition, the communication system can accept the newly-added vehicle through a simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a diagram showing the configuration of a communication system according to the first embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram showing the relationship between the communication management unit, access point, and traveling vehicle.

[0029] Figure 3 This is a timing chart showing the transmission timing of a beacon for accepting a newly-established traveling vehicle as a wireless communication partner.

[0030] Figure 4 This is a diagram showing the relationship between the idle time of wireless polling communication and the start timing of connection sequencing.

[0031] Figure 5 This is a schematic diagram showing the relationship among the communication management unit, access points, and traveling vehicles in the second embodiment.

[0032] Figure 6 This is a diagram showing the relationship between the predicted idle time and the start timing of the connection sequencing in the second embodiment.

[0033] Figure 7 This is a diagram showing an example of connection sequencing according to the second embodiment. DETAILED DESCRIPTION

[0034] Next, embodiments of the present invention will be described with reference to the drawings. Figure 1 It is a diagram showing the configuration of a communication system 100 according to the first embodiment of the present invention. Figure 2 Schematic diagram showing the relationship among the communication management unit 3 , the access point 2 , and the traveling vehicle 1 . Figure 3 1 is a timing chart showing the transmission timing of a beacon for accepting the newly-built traveling vehicle 1a as a wireless communication partner. Figure 4 The diagram shows the relationship between the idle time of the wireless polling communication and the start timing of the connection sequence with respect to the access point 2 in the communication area A among the four communication areas A to D managed by the communication management unit 3 .

[0035] Figure 1 The communication system 100 shown is used for, for example, a conveying system installed in a semiconductor manufacturing factory having a plurality of processing devices (not shown in the figure), an automatic warehouse having a plurality of stockers (not shown in the figure), or the like.

[0036] A plurality of communication areas are formed in the communication system 100. The communication system 100 includes a plurality of traveling vehicles (traveling vehicles) 1, a plurality of access points 2, and a communication management unit (controller) 3 in each communication area. The number of communication areas is arbitrary, and may be one, for example.

[0037] The maximum number N of traveling vehicles 1 included in each communication area max For example, the unit communication time t0 required for one communication between one traveling vehicle 1 and the communication management unit 3 is considered and set in advance. The traveling vehicle 1 sometimes moves between multiple communication areas while traveling. Therefore, the number of traveling vehicles 1 belonging to each communication area is greater than 0 N. max Change appropriately within the following range.

[0038] Each traveling trolley 1 is a conveying device that travels in a travel area formed by a track 4. The track 4 is, for example, a ceiling track suspended from the ceiling of a semiconductor manufacturing plant, an automatic warehouse, etc. Alternatively, the track 4 may be laid on the ground. The traveling trolley 1 can be used, for example, to transport a transport object such as a FOUP between a processing device and a stacking rack. FOUP is the abbreviation of FrontOpening Unify Pod.

[0039] The traveling trolley 1 is, for example, an elevated traveling vehicle that travels along a track 4 suspended from a ceiling. In this embodiment, the traveling trolley 1 travels along the track 4 in a state where its main body (not shown) is suspended downward from the track 4. The elevated traveling vehicle is configured as, for example, an OHT. OHT is the abbreviation of Overhead Hoist Transfer. However, this is not limited to this, and the traveling trolley 1 may also be configured by, for example, an RGV, which is a rail-guided unmanned transport vehicle that travels along a track 4 set on the ground. RGV is the abbreviation of Rail Guided Vehicle.

[0040] Furthermore, the traveling vehicle 1 may also be configured as a trackless traveling vehicle represented by an AGV, which is an unmanned transport vehicle. AGV is the abbreviation of Automated Guided Vehicle. In this case, the traveling path and traveling area of ​​the traveling vehicle 1 are substantially determined by a sensing tape such as a magnetic tape attached to the ground, or a guide composed of a barcode, a two-dimensional code, etc.

[0041] like Figure 2As shown, the traveling trolley 1 is provided with a trolley wireless communication unit (wireless communication unit) 11 and a trolley control unit 12. A well-known computer is built into the traveling trolley 1. The computer is provided with a CPU, an HDD, a ROM, a RAM, etc. The HDD, the ROM, and the RAM constitute a trolley storage unit (not shown) that stores various information related to wireless communication. Programs for realizing wireless communication, etc. are stored in the non-volatile memory of the trolley storage unit composed of the HDD and the ROM. Through the cooperation of the above-mentioned hardware and software, the computer can be operated as the trolley wireless communication unit 11 and the trolley control unit 12.

[0042] The trolley wireless communication unit 11 communicates with the communication management unit 3 via wireless communication with the access point 2 in accordance with a predetermined wireless communication standard. As a wireless communication standard, for example, IEEE802.11 can be used, but any wireless communication standard that uses management frames (Japanese: マネジメントフレーム) in wireless communication is not limited thereto. Wireless communication can be achieved by a wireless LAN that complies with the wireless communication standards exemplified above.

[0043] The vehicle wireless communication unit 11 performs wireless communication with one of the plurality of access points 2 corresponding to the travel position of the travel vehicle 1. The wireless communication ranges of the plurality of access points 2 are different. Therefore, in each communication area described later, the access point 2 to which the vehicle wireless communication unit 11 performs wireless communication can be changed according to the travel position of the travel vehicle 1 (roaming between access points 2).

[0044] The vehicle control unit 12 controls the wireless communication of the vehicle wireless communication unit 11, and instructs the vehicle wireless communication unit 11 on the communication channel and communication rate corresponding to the driving position of the vehicle. The vehicle control unit 12 obtains the driving position information indicating the driving position of the vehicle in the driving area, for example, via a position sensor (not shown) installed on the driving vehicle 1. The acquisition of the driving position information is performed, for example, as follows.

[0045] That is, a plurality of identifications (such as bar codes, etc.) are provided along the track 4 on which the traveling vehicle 1 travels, and the vehicle control unit 12 of the traveling vehicle 1 obtains the driving position information of the vehicle by determining the identification based on the information read by the identification reader not shown. Alternatively, reference marks (ID tags) are provided at predetermined intervals along the track 4 on which the traveling vehicle 1 travels, and the vehicle control unit 12 of the traveling vehicle 1 may also calculate the distance from the reference mark by counting the output of the wheel encoder, thereby obtaining the driving position information of the vehicle. Alternatively, the position sensor mounted on the traveling vehicle 1 may be constituted by a light receiver. In this embodiment, a plurality of light transmitters are provided along the track 4 on which the traveling vehicle 1 travels. The coordinates of each light transmitter in the driving area are stored in advance by the vehicle storage unit in a state where the coordinates are established in correspondence with the identification information of each light transmitter. Each light transmitter transmits a light signal containing identification information for identifying the device. When the traveling vehicle 1 passes through a predetermined position on the track 4, the position sensor (light receiver) receives the light signal transmitted from the light transmitter. The vehicle control unit 12 of the traveling vehicle 1 identifies the optical transmitter based on the received optical signal, thereby acquiring the traveling position information of the vehicle.

[0046] In the vehicle control unit 12 , correspondence information such as the communication channel and the communication rate used for wireless communication at each driving position within the driving range is stored in advance for the entire communication system 100 .

[0047] Based on the driving position information of the vehicle obtained as described above, the vehicle control unit 12 obtains information such as the communication channel and the communication rate from the stored corresponding information, and instructs the vehicle wireless communication unit 11. However, this is not limited to this, and the information such as the communication rate may be obtained through wireless communication with the access point 2.

[0048] The access point 2 is connected to the communication management unit 3 via the wired LAN 5 using a LAN cable, and performs wired communication with the communication management unit 3. In the wired LAN 5, an appropriate number of switching hubs (not shown) and the like may be arranged.

[0049] The access point 2 performs wired communication with the communication management unit 3 and forms a wireless network with itself as the center. The access point 2 can perform wireless communication with the traveling vehicle 1 existing in the wireless communication area with itself as the center.

[0050] In the communication system 100 of the present embodiment, a plurality of access points 2 are installed along the track 4 so that the entire travel area where the travel vehicle 1 travels is covered within the wireless communication range of the access points 2 .

[0051] In the present embodiment, each access point 2 is pre-set with information about the position of the traveling vehicle 1 in the traveling area of ​​the traveling vehicle 1 included in the wireless communication range with which the wireless communication is to be performed. In particular, in a portion where the wireless communication ranges of two access points 2 partially overlap, the access point 2 responsible for each position of the traveling area included in the overlapping portion is pre-determined.

[0052] In this embodiment, the correspondence between each position of the traveling vehicle 1 and the access point 2 for wireless communication with the traveling vehicle 1 is determined in advance. Therefore, the correspondence information such as the communication channel and communication rate for wireless communication performed at each traveling position within the traveling range can be prepared in advance.

[0053] The communication management unit 3 is a computer for managing each traveling vehicle 1 that is less than a predetermined number. Figure 1 The plurality of transport tasks provided by the transport management unit 6 or the like in the upper layer are respectively allocated to any of the plurality of travel vehicles 1 managed, and the travel routes and the like of the respective travel vehicles 1 are determined.

[0054] The transport management unit 6 comprehensively controls the transport system to which the communication system 100 is applied. The transport management unit 6 is composed of one or more computers, and performs various controls associated with transport management.

[0055] For example, Figure 1 As shown, the plurality of communication management units 3 managed by the transport management unit 6 are connected to each other so as to be able to communicate with each other via the wired LAN 5. The communication management units 3 may be configured to communicate with each other via the transport management unit 6 without being directly connected to each other.

[0056] The communication management unit 3 is configured as, for example, a well-known computer including a CPU, a ROM, a RAM, a HDD, etc. (not shown). Various programs, data related to management, etc. are stored in the ROM, the RAM, and the HDD.

[0057] The communication management unit 3 wirelessly performs polling communication to sequentially inquire a plurality of traveling vehicles 1 existing in the communication area under its jurisdiction via the access point 2. The plurality of access points 2 provided in the communication system 100 may perform wireless communication using the same communication channel. In this case, the distance between the plurality of access points 2 using the same communication channel should be set to be large enough to prevent communication interference. In the case where there is no possibility of communication interference between the plurality of access points 2, in the polling communication performed via these access points 2, other access points 2 do not need to be considered. That is, the access point 2 performs wireless polling communication at the polling period T.

[0058] On the other hand, when there is a possibility that communication interference occurs between multiple access points 2 using the same communication channel, the polling cycle T is divided. For example, when four access points 2 use the same communication channel for wireless communication, when there is a possibility that communication interference occurs between the four access points 2, the polling cycle T is divided into four. That is, the polling cycle divided into four is respectively allocated to the four access points 2. Hereinafter, the period allocated in this way is sometimes referred to as the allocation period Ta. Each access point 2 performs wireless polling communication within the allocation period Ta allocated to itself. Therefore, the allocation period Ta can be regarded as a period during which the communication management unit 3 can perform wireless polling communication with the traveling vehicle 1 under the access point 2 via each access point 2.

[0059] The length of the allocation period Ta is based on the unit communication time t0 and the maximum number N of traveling vehicles 1 in the communication area that the access point 2 is responsible for. max The length of the allocation period Ta is set to, for example, the unit communication time t0 and the maximum number N of traveling vehicles 1 max That is, Ta = t0 × N max Thus, no matter how many traveling vehicles 1 are present in the communication area, the time required for wireless polling communication can always be ensured. When the polling cycle T is divided according to the number of access points 2, the divided polling cycles (ie, allocation periods Ta) need to satisfy the above conditions.

[0060] The communication management unit 3 sequentially accesses a plurality of traveling vehicles 1 existing in the communication area of ​​the access point 2 within each polling cycle T for each access point 2 to communicate. The polling communication is performed wirelessly via the access point 2. After the communication management unit 3 completes the communication with each traveling vehicle 1 within one polling cycle T (strictly speaking, within the allocated period Ta), it waits for the wireless polling communication with the traveling vehicle 1 until the next polling cycle T (allocated period Ta) arrives.

[0061] Each of the traveling vehicles 1 traveling on the track 4 within the communication range of the communication system 100 is registered in advance in the communication system 100. This registration will be described later.

[0062] Hereinafter, a case where the traveling vehicle 1 moves from one communication area to another communication area while traveling (roaming between communication areas of different communication management units 3) is considered. Here, the communication management unit 3 that manages the communication area of ​​the movement source of the traveling vehicle 1 is referred to as the first communication management unit, and the other communication management unit 3 that manages the communication area of ​​the movement destination is referred to as the second communication management unit.

[0063] The first communication management unit transmits the identification information of the traveling vehicle 1 that has come out of the communication area under its jurisdiction to the second communication management unit via the wired LAN 5. Almost simultaneously, the first communication management unit deletes the identification information of the traveling vehicle 1 that has come out of the communication area under its jurisdiction from the list of wireless polling communication objects stored in the storage unit. As a result, the traveling vehicle 1 is no longer included in the objects of the next and subsequent wireless polling communications based on the first communication management unit. The second communication management unit adds the identification information of the traveling vehicle 1 received from the first communication management unit to the list of wireless polling communication objects. As a result, the traveling vehicle 1 is included in the objects of the next and subsequent wireless polling communications based on the second communication management unit.

[0064] Next, a method for causing the communication system 100 to accept the newly built traveling vehicle 1a as a wireless communication target when a newly built traveling vehicle 1, i.e., a newly built traveling vehicle (new traveling vehicle) 1a, is added to an existing transportation system will be described. In this specification, the fact that the communication system 100, which has already wirelessly communicated with several traveling vehicles 1, additionally accepts the newly built traveling vehicle 1a as a wireless communication target is sometimes referred to as "entering the line (Japanese: entering the line)". In this embodiment, along with the entry, the communication system 100 (any communication management unit 3 and transportation management unit 6) recognizes the existence of the newly built traveling vehicle 1a and performs various processes so that wireless communication with the newly built traveling vehicle 1a can be performed.

[0065] In the communication system 100 of the present embodiment, a dedicated position for adding a new traveling vehicle 1a, that is, a vehicle adding position 10 is provided. The vehicle adding position 10 can be set arbitrarily, but for example, Figure 1 As shown, it is preferably set at a position that does not hinder the travel of the existing travel vehicle 1. In addition, it is also possible to add a new travel vehicle 1a at an arbitrary position on the track 4 without particularly providing a dedicated vehicle adding position 10.

[0066] After the operator places the newly built traveling trolley 1a at the trolley additional position, Figure 3 As shown, the transport management unit 6 performs a new vehicle driving operation (accepts instructions). The new vehicle driving operation is an operation to indicate the addition of the new vehicle 1a. As a specific operation, it can be considered that, for example, the operator clicks a menu or icon instructing the new vehicle to drive in in the transport management unit 6. However, it is not limited to this.

[0067] When the new vehicle is operated to move in, the transport management unit 6 recognizes that there is a new vehicle 1a to move in. The transport management unit 6 sends a move-in instruction for moving the new vehicle 1a to the communication management unit 3 that manages the communication area including the vehicle adding position.

[0068] When the communication management unit 3 receives the driving instruction for the newly-built traveling vehicle 1a from the transportation management unit 6, it obtains the idle time during which wireless polling communication is not substantially performed in the allocation period Ta allocated to the access point 2 in the area including the vehicle addition position 10 in the next polling cycle T. Figure 3 as well as Figure 4 Idle time is exemplified in Figure 4 In FIG. 1 , the communication area A is a communication area including the newly built traveling vehicle 1 a.

[0069] Almost at the same time as the assigned period Ta is started, wireless polling communication with the traveling vehicle 1 is started. If there are multiple traveling vehicles 1 in the communication area under jurisdiction, Figure 3 As briefly shown in FIG. 1 , wireless polling communication is performed one by one while different traveling vehicles 1 are connected. The idle time in the allocation period Ta means that the access point 2 in the area including the vehicle addition position 10 completes the wireless polling communication with all traveling vehicles 1 (equivalent to Figure 4 The idle time is the idle time after the entire polling period (the entire polling period) until the end of the allocation period Ta. The idle time varies according to the number of traveling vehicles 1 under the access point 2, and the more the number of traveling vehicles 1, the shorter it is, and the fewer the number, the longer it is. The communication management unit 3 calculates the idle time based on the current time and the end time of the allocation period Ta when the wireless polling communication with all the traveling vehicles 1 in the communication area under its jurisdiction is completed.

[0070] The communication management unit 3 compares the idle time calculated as described above with the pre-set connection required time (predetermined time) to determine whether the connection sequence for the newly-built traveling vehicle 1a can be completed within the idle time (connection availability determination step). The connection required time is the time required from the start to the completion of the connection sequence executed in order for the communication system 100 to accept the newly-built traveling vehicle 1a.

[0071] In the above determination, when it is determined that the idle time is longer than the time required for connection, the communication management unit 3 immediately executes the connection sequence (wireless communication party adding process).

[0072] The following is a detailed description of the connection sequence. Figure 3 As shown, the communication management unit 3 transmits a beacon containing prescribed information in a broadcast format via (more specifically, instructs) the access point 2 within the wireless communication range centered on the access point 2. The information described in the beacon includes the identification information (e.g., MAC address, etc.) of the access point 2 as information required for communication. Other information, such as the communication rate, may also be included in the information required for communication.

[0073] The newly built traveling vehicle 1a located in the wireless communication range receives the beacon broadcasted from the access point 2, stores the information (identification information, etc.) of the access point 2 included in the beacon, and thereby performs settings related to wireless communication.

[0074] Then, the newly built vehicle 1a sends an advance response that describes the vehicle information used for wireless communication to the communication management unit 3 via wireless communication with the access point 2. The access point 2 that receives the advance response stores the information of the newly built vehicle 1a contained in the advance response and sends the information to the communication management unit 3. The communication management unit 3 stores the information of the newly built vehicle 1a so as to add the newly built vehicle 1a as an object of wireless polling communication. That is, the information related to the wireless communication of the newly built vehicle 1a is added to the list of objects of wireless polling communication of the communication management unit 3. In addition, the information includes identification information such as the MAC address of the newly built vehicle 1a.

[0075] Furthermore, the communication management unit 3 transmits the received information of the newly-built traveling vehicle 1a to the transport management unit 6. The transport management unit 6 stores the information of the newly-built traveling vehicle 1a received from the communication management unit 3. In this way, the communication system 100 recognizes the existence of the newly-built traveling vehicle 1a.

[0076] As described above, the newly built traveling vehicle 1a has completed its movement into the communication system 100. The communication management unit 3 sequentially performs wireless polling communication with the plurality of traveling vehicles 1 including the newly built traveling vehicle 1a via the access point 2 in the next polling cycle T (allocation period Ta).

[0077] like Figure 3 as well as Figure 4 As shown, the start timing of the connection sequence is automatically adjusted so that the wireless communication accompanying the connection sequence does not conflict with the wireless polling communication. Therefore, it is possible to avoid the transmission and reception of the beacon from hindering the wireless polling communication.

[0078] On the other hand, in the above determination, if it is determined that the idle time is less than the required connection time, the communication management unit 3 does not perform the connection sequencing for the newly-built traveling vehicle 1a, and waits until the next polling cycle T starts. Then, the communication management unit 3 determines again whether the idle time is sufficient in the next polling cycle T (allocated period Ta). The communication management unit 3 repeatedly and continuously performs the above processing until the newly-built traveling vehicle 1a is driven.

[0079] As described above, the driving method (i.e., wireless communication receiving method) of the present embodiment autonomously finds the timing of driving the newly built traveling vehicle 1a based on the driving operation of the newly built traveling vehicle, thereby realizing the seamless introduction of the newly built traveling vehicle 1a. In addition, by using the driving method of the present embodiment, the information of the wireless communication party can be obtained and registered through wireless communication performed on the spot. Therefore, compared with the method in which the operator manually inputs the identification information of the newly built traveling vehicle 1a into the transportation management unit 6, it is possible to avoid misregistration caused by errors. In addition, it is possible to prevent the beacon for the driving of the newly built traveling vehicle 1a from being sent in the middle of the wireless polling communication with the existing traveling vehicle 1. Therefore, it is possible to avoid the obstruction of the wireless polling communication due to the transmission and reception of the beacon. In addition, the driving method of the present embodiment can also be applied to the case where the traveling vehicles 1 traveling on the track 4 within the communication range of the communication system 100 are registered in the communication system 100 before operation, and the workload of the operator when the communication system is introduced can be reduced.

[0080] As described above, the wireless communication receiving method of the present embodiment is a method for causing the communication system 100 to accept a newly built traveling vehicle 1a as a wireless communication object. The communication system 100 includes a communication management unit 3, an access point 2, and a plurality of traveling vehicles 1. The access point 2 is connected to the communication management unit 3. The plurality of traveling vehicles 1 each have a vehicle wireless communication unit 11. The communication system 100 performs wireless polling communication between the communication management unit 3 and the plurality of traveling vehicles 1 via the access point 2 at intervals of a predetermined polling period T. The wireless communication receiving method performs a process including a wireless communication party adding step. In the wireless communication party adding step, within the polling period T, after the wireless polling communication between the communication management unit 3 and the plurality of traveling vehicles 1 is completed and until the end of the period in which the wireless polling communication can be performed, that is, during the idle time (refer to Figure 4 ) to execute connection sequencing accompanied by wireless communication for allowing the communication system 100 to accept the newly-established traveling vehicle 1a.

[0081] In this way, by executing the connection sequence of the newly-built traveling vehicle 1a during the idle time when the wireless polling communication is not being performed, the influence of the connection sequence execution on the wireless polling communication can be eliminated. In addition, the communication system 100 can accept the newly-built traveling vehicle 1a through a simple operation.

[0082] In addition, in the wireless communication receiving method of the present embodiment, a process including a connection determination step of determining whether the idle time is longer than a prescribed time is performed. If it is determined in the connection determination step that the idle time is longer than the prescribed time, a wireless communication party adding step is performed. If it is determined in the connection determination step that the idle time is shorter than the prescribed time, the wireless communication party adding step is not performed.

[0083] This makes it possible to reliably prevent the wireless polling communication from being hindered by the execution of the connection sequence.

[0084] Furthermore, in the wireless communication receiving method of the present embodiment, in the wireless communication party adding step, the communication management unit 3 wirelessly transmits a beacon for starting connection sequencing via the access point 2 during an idle time.

[0085] This eliminates the need to input information for wireless communication (for example, the MAC address of the access point 2) to the newly built traveling vehicle 1a in advance. Therefore, input errors can be prevented and the operator's workload can be reduced.

[0086] Furthermore, in the wireless communication receiving method of the present embodiment, in the wireless communication party adding step, the communication management unit 3 transmits a beacon for starting connection sequencing in response to a new traveling vehicle entry operation input by an operator.

[0087] Thus, since a beacon is not transmitted when there is no operation by the operator, it is possible to avoid unnecessary transmission when no new traveling vehicle 1 a is built.

[0088] Next, a second embodiment will be described. Figure 5 This is a schematic diagram showing the relationship among the communication management unit 3, the access point 2, and the traveling vehicle 1 in the second embodiment. Figure 6 It is a diagram showing the relationship between the idle time predicted by the newly built traveling vehicle 1b and the start timing of the connection sequence. In the description of this embodiment, the same or similar components as those in the above-mentioned embodiment are denoted by the same reference numerals and the description thereof may be omitted.

[0089] In the communication system 100 of the present embodiment, the access point 2 does not broadcast a beacon for the new traveling vehicle 1b to enter, but instead broadcasts a beacon for requesting acceptance to the new traveling vehicle 1b scheduled to enter the communication system 100.

[0090] like Figure 5 As shown, the newly built traveling vehicle 1 b (ie, the traveling vehicle 1 ) of the present embodiment includes a wireless monitoring unit 13 and a learning unit 14 in addition to the vehicle wireless communication unit 11 and the vehicle control unit 12 .

[0091] The newly built traveling vehicle 1 b can cause the built-in known computer to operate as the wireless monitoring unit 13 and the learning unit 14 through the cooperation of hardware and software included in the built-in computer.

[0092] The wireless monitoring unit 13 monitors the communication channel indicated by the vehicle control unit 12, and obtains information such as wireless communication packets and reception strength in the communication channel. The wireless monitoring unit 13 outputs the obtained information to the learning unit 14. The vehicle control unit 12 indicates in advance to the wireless monitoring unit 13 the communication channel of the access point 2 corresponding to the driving position of the newly-built vehicle 1b. By monitoring the communication channel, the wireless monitoring unit 13 can grasp the communication status of the communication management unit 3 via the access point 2 near itself. In other words, when the newly-built vehicle 1b exists within the communication range of the specified access point 2, the wireless monitoring unit 13 of the newly-built vehicle 1b monitors the communication channel of the access point 2 and grasps its communication status.

[0093] The learning unit 14 predicts the time (idle time) when the communication management unit 3 does not perform wireless polling communication in each polling cycle T (strictly speaking, in the allocation period Ta) by analyzing (learning) wireless communication packets, etc. (idle time estimation process). The learning unit 14 outputs the predicted idle time to the carriage control unit 12.

[0094] However, assuming that the monitoring period of the communication channel by the wireless monitoring unit 13 includes only a part of the period of the polling cycle T, it is impossible to correctly obtain the number N of traveling vehicles 1 that are the object of wireless polling communication in the communication area based on the wireless communication packets obtained by the monitoring. Therefore, it is necessary to set the period during which the wireless monitoring unit 13 monitors the wireless communication to be long enough so as to include the entire period of at least one polling cycle T. For example, it is conceivable to set the length of the monitoring period of wireless communication to be more than twice the polling cycle T. As a result, the learning unit 14 can correctly obtain the number of traveling vehicles 1 that are the object of wireless polling communication from the communication packets received by the wireless monitoring unit 13. In addition, the length of the monitoring period of wireless communication by the wireless monitoring unit 13 can also be appropriately and dynamically changed according to the number of traveling vehicles 1 in each communication area and the length of the polling cycle T (allocated period Ta).

[0095] The learning unit 14 can obtain the number of traveling vehicles 1 in the communication area where the newly-installed traveling vehicle 1b is scheduled to be introduced based on the number of times the communication management unit 3 performs wireless polling communications. The learning unit 14 obtains the number of times the communication management unit 3 performs wireless polling communications, for example, by analyzing the inherent identifier such as the MAC address of the traveling vehicle 1 contained in the acquired wireless communication packet. After obtaining the number of traveling vehicles 1, the learning unit 14 calculates the unit communication time t0 for each traveling vehicle 1. There are several methods for calculating the unit communication time t0. For example, the unit communication time t0 can be obtained by dividing the actual communication time (hereinafter sometimes referred to as the entire polling period) required for the communication management unit 3 to perform wireless polling communications on all traveling vehicles 1 in the communication area where the newly-installed traveling vehicle 1b is introduced by the number of traveling vehicles 1 in the communication area. The timing of the start and end of the entire polling period can be obtained based on the monitoring result of the wireless monitoring unit 13.

[0096] Due to the above-mentioned roaming between communication areas, the traveling vehicle 1 may move from another communication area between the polling cycle T and the next polling cycle T. Although it is impossible to know in advance whether this roaming will occur, even if it occurs, the number of traveling vehicles 1 that will be polled by switching the polling cycle T once is actually limited. This is because the communication management unit 3 has a design upper limit on the number of traveling vehicles 1 that can be controlled within the communication area. Therefore, the learning unit 14 subtracts the number of traveling vehicles 1 controlled within the communication area from the upper limit number, and multiplies this number by the unit communication time t0, thereby obtaining the preparation period. In addition, the above-mentioned upper limit number is preset and stored in the newly created traveling vehicle 1b.

[0097] The learning unit 14 also obtains the allocation period Ta of the access point 2 in charge of the communication area of ​​the newly introduced traveling vehicle 1b based on the monitoring result of the wireless monitoring unit 13. The allocation period Ta can be obtained based on the timing of the access point 2 starting wireless polling communication in the polling cycle T and the timing of other access points 2 starting wireless polling communication for other communication areas after the wireless polling communication ends. However, the acquisition of the allocation period Ta based on this method is based on the timing of the wireless polling communication starting in the polling cycle T. Figure 6 It is assumed that wireless polling communication is performed not only in the communication area A but also in the communication area B through the monitoring channel of the wireless monitoring unit 13 and that the newly built traveling vehicle 1b can monitor the wireless polling communication in both the communication area A and the communication area B.

[0098] The information of the allocation period Ta may be stored in advance on the newly-built traveling vehicle 1 b side. In this case, the allocation period Ta does not need to be estimated by the learning unit 14 .

[0099] Then, the learning unit 14 subtracts the total polling time from the allocated period Ta, and further subtracts the preparation time, thereby estimating the idle time in the next polling cycle T. Furthermore, the learning unit 14 compares the idle time with the required connection time, and determines whether the connection sequencing of the newly-built traveling vehicle 1b can be completed within the idle time (connection availability determination step).

[0100] When the idle time is longer than the time required for connection, the vehicle control unit 12 determines the timing at which the vehicle transmits a beacon indicating a request for wireless communication to proceed to the communication system 100 in the next polling cycle T.

[0101] The beacon transmission timing (connection sequencing start timing) is determined based on the analysis result input from the learning unit 14. Specifically, in the current polling cycle T, the beacon transmission timing is calculated with the timing when the access point 2 in charge of the communication area of ​​the newly introduced traveling vehicle 1b ends the wireless polling communication with all subordinate traveling vehicles 1 as the starting point. Specifically, the beacon transmission timing is the timing obtained by adding a preliminary period taking into account the situation where the traveling vehicle moves from other communication areas to the starting point.

[0102] The beacon transmission timing can also be calculated starting from the end of the allocation period Ta in the current polling cycle T. In this case, the beacon transmission timing is a time obtained by tracing back from the end of the allocation period Ta to the time required for connection sequencing to be completed.

[0103] On the other hand, when the idle time is less than the required connection time, the trolley control unit 12 does not instruct the trolley wireless communication unit 11 to send a beacon. In this case, the wireless communication is continuously monitored by the wireless monitoring unit 13, and the learning unit 14 determines whether the connection is possible again based on the monitoring result of the new polling cycle T. The above process is repeated until the idle time becomes longer than the required connection time.

[0104] The wireless monitoring unit 13 monitors wireless communication in real time, and outputs the acquired wireless communication packets to the learning unit 14. Therefore, it is possible to make a determination in accordance with the current situation as to whether the connection of the newly established traveling vehicle 1b is possible.

[0105] Next, refer to Figure 7 An example of a connection sequence performed by the traveling vehicle 1 in order to proceed to the communication system 100 will be briefly described. Figure 7 This is a diagram showing an example of connection sequencing according to the second embodiment.

[0106] After the newly built traveling trolley 1b is arranged at the trolley additional position, Figure 7As shown, the vehicle control unit 12 outputs information of the communication management unit 3 that governs the communication area to be introduced into the newly-built traveling vehicle 1b (or information of the access point 2 through which the communication management unit 3 passes) to the vehicle wireless communication unit 11. This information includes, for example, identification information of the communication management unit 3 or the access point 2, a communication channel, and the like.

[0107] The vehicle wireless communication unit 11 continuously monitors the communication channel via the wireless monitoring unit 13. As described above, when it is determined that there is free time to complete the connection sequence, the vehicle wireless communication unit 11 sends a beacon in a broadcast format at the start timing of the connection sequence instructed by the vehicle control unit 12. The beacon contains the identification information (e.g., MAC address) of the newly-established vehicle 1b.

[0108] The access point 2 that has received the beacon transmits a response frame to the newly-built traveling vehicle 1b. Furthermore, the access point 2 transmits the beacon received from the newly-built traveling vehicle 1b (or the information of the newly-built traveling vehicle 1b included in the beacon) to the communication management unit 3.

[0109] The communication management unit 3 stores the information of the newly-built traveling vehicle 1 b included in the beacon, and registers the newly-built traveling vehicle 1 b as a wireless polling communication partner. Then, the communication management unit 3 transmits the information of the newly-built traveling vehicle 1 b to the transport management unit 6 .

[0110] In this way, the access point 2 completes the entry of the newly built traveling vehicle 1b by registering the information of the newly built traveling vehicle 1b in the communication management unit 3 and the transport management unit 6. As a result, the communication management unit 3 can start communication with the newly built traveling vehicle 1b via the access point 2.

[0111] As described above, in the wireless communication receiving method of the present embodiment, in the wireless communication party adding step, the newly built traveling vehicle 1 b wirelessly transmits a beacon for starting the connection sequencing during an idle time.

[0112] This eliminates the need to input information for wireless communication (for example, the address of the newly-built vehicle 1b) into the access point 2 or the communication management unit 3 in advance. This prevents input errors from occurring and reduces the workload on operators.

[0113] In the wireless communication receiving method of the present embodiment, the newly-built traveling vehicle 1b performs processing including an idle time estimation step. In the idle time estimation step, the newly-built traveling vehicle 1b monitors wireless polling communication between the communication management unit 3 and a plurality of traveling vehicles 1 to estimate idle time.

[0114] This allows the newly built vehicle 1b to estimate the idle time when wireless polling communication is not performed. Therefore, the newly built vehicle 1b can send a beacon for participating in wireless communication during the time period when wireless polling communication is not performed. That is, it is possible to avoid the transmission of a beacon hindering wireless polling communication.

[0115] As mentioned above, although the preferred embodiment of the present invention was described, the above-mentioned structure can be changed as follows, for example.

[0116] In the first embodiment, the execution of the above-mentioned connection sequence related to the advance of the newly built traveling vehicle 1 a (determination of the beacon transmission time, etc.) may be performed by the control unit included in the access point 2 .

[0117] In the first embodiment, a sensor for detecting the presence of a newly-built traveling vehicle 1a may be provided at the vehicle adding position 10 predetermined for adding the newly-built traveling vehicle 1a. In this case, instead of the operator manually operating the newly-built traveling vehicle to move in, it is possible to automatically determine whether the communication system 100 needs to accept the newly-built traveling vehicle 1a based on the detection result of the sensor. In this configuration, the detection result of the sensor indicating the presence of the newly-built traveling vehicle 1a is sent to the transport management unit 6 as an acceptance command instead of the newly-built traveling vehicle to move in.

[0118] In the first embodiment and the second embodiment, the communication management unit 3 or the traveling vehicle 1 may actively transmit a beacon when the idle time in each polling cycle T is longer than the time required for connection.

[0119] In the first embodiment and the second embodiment, instead of the idle time, the maximum number N of traveling vehicles 1 that can communicate within the communication area may be used. max The number of available vehicles obtained by subtracting the number of actually existing traveling vehicles 1 is used to determine whether or not to execute the connection sequencing of the newly-created traveling vehicles 1a and 1b.

[0120] In the first and second embodiments, it is also possible to determine whether to execute connection sequencing by comparing the entire polling period with a preset threshold time instead of the idle time. Specifically, when the entire polling period is less than the threshold time, connection sequencing is executed. In addition, the threshold time can be set based on the allocation period Ta and the execution time of connection sequencing, for example.

[0121] In the first embodiment and the second embodiment, when one polling cycle T is divided into a plurality of parts and allocated to each communication management unit 3, the parts may be divided equally or unequally.

[0122] The timing and length of the allocation period Ta may also be changed dynamically during the operation of the communication system 100. In the first embodiment, even if the allocation period Ta changes dynamically, it is easy to obtain the idle time. In the second embodiment, if the timing and length of the allocation period Ta in the next polling cycle T can be predicted in some form on the new traveling vehicle 1b side, the idle time can be estimated based on this.

[0123] When the number of communication areas is small (for example, one), one polling cycle T can be used as one allocation period Ta without dividing the polling cycle T. In addition, the channel used for wireless polling communication can be used as only one channel instead of multiple channels.

[0124] In the second embodiment, the newly built traveling vehicle 1b may scan the communication channels by the wireless monitoring unit 13 (or the vehicle wireless communication unit 11) to acquire the monitored communication channel.

[0125] In the newly built traveling vehicle 1b of the second embodiment, the wireless monitoring unit 13 may monitor the usage rate of the communication channel without acquiring the wireless communication packet. In this case, for example, when the usage rate of the communication channel is below a threshold close to zero, it can be determined that wireless polling communication is not performed.

[0126] In the second embodiment, the monitoring period of the wireless monitoring unit 13 may be determined to include all the times of more than 2 times of the polling cycle T. In this case, the learning unit 14 can obtain the entire polling period for each polling cycle T. By obtaining the arithmetic mean of a plurality of entire polling periods, the obtained average value can be used, for example, to determine the transmission timing of the beacon. The length of the preparation period can also be adjusted based on the value (for example, variance) representing the deviation of the entire polling period.

[0127] Explanation of symbols

[0128] 1 Traveling trolley (traveling vehicle)

[0129] 1a Newly built traveling vehicle (newly built traveling vehicle)

[0130] 2 Access Points

[0131] 3. Communication Management Unit (Controller)

Claims

1. A wireless communication receiving method, which enables a communication system to accept a newly-built vehicle as a wireless communication object, The communication system comprises a controller, an access point connected to the controller, and a plurality of traveling vehicles each having a wireless communication unit. The communication system performs wireless polling communication between the controller and the plurality of traveling vehicles via the access point at every predetermined polling cycle. The wireless communication receiving method is characterized in that A process including a wireless communication party adding step is performed, wherein the wireless communication party adding step executes connection sequencing accompanied by wireless communication in the polling cycle, after the wireless polling communication between the controller and the plurality of traveling vehicles is completed and in an idle time until the end of a period during which wireless polling communication is possible, the connection sequencing being used to allow the communication system to accept the newly added traveling vehicle; performing a process including a connection availability determination step of determining whether the idle time is longer than a predetermined time, When it is determined in the connection availability determination step that the idle time is longer than a predetermined time, the wireless communication party adding step is performed. If it is determined in the connection availability determination step that the idle time is less than the predetermined time, the wireless communication party adding step is not performed.

2. The wireless communication receiving method according to claim 1, characterized in that: In the wireless communication party adding step, the controller wirelessly transmits a frame for starting the connection sequencing via the access point during the idle time.

3. The wireless communication receiving method according to claim 2, characterized in that: In the wireless communication party adding step, the controller transmits a frame for starting the connection sequencing according to an acceptance command input by an operator.

4. The wireless communication receiving method according to claim 1, characterized in that: In the wireless communication adding step, the newly-built vehicle wirelessly transmits a frame for starting the connection sequencing during the idle time.

5. The wireless communication receiving method according to claim 4, characterized in that: The newly built traveling vehicle performs a process including an idle time estimating step of estimating the idle time by monitoring the wireless polling communication between the controller and the plurality of traveling vehicles.

6. A communication system comprising a controller, an access point connected to the controller, and a plurality of traveling vehicles each having a wireless communication unit, wherein: The controller performs wireless polling communication with a predetermined number of the traveling vehicles under its control via the access point at predetermined polling cycles. In the polling cycle, after the wireless polling communication between the controller and the predetermined number of the traveling vehicles via the access point is completed and in an idle time until the end of the polling cycle, a connection sequence accompanied by wireless communication is executed, the connection sequence being used to accept wireless communication with a newly-created traveling vehicle that is not included in the plurality of traveling vehicles that are the objects of the wireless polling communication; performing a process including a connection availability determination step of determining whether the idle time is longer than a predetermined time, When it is determined in the connection availability determination step that the idle time is longer than a predetermined time, the wireless communication party adding step is performed. If it is determined in the connection availability determination step that the idle time is less than the predetermined time, the wireless communication party adding step is not performed.

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