JP2001042940A - Moving vehicle operation control system and radio communicating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To substantially prevent a communication from being broken by changing a communication partner to the adjacent in-communication repeater (AP) which has the largest reception intensity indicated by acquired adjacent AP data among adjacent APs when the reception intensity of a signal oscillated by an AP is less than a given threshold. SOLUTION: Data indicating adjacent APs are registered in a corresponding high-speed roaming table (S1). A moving vehicle acquires data indicating the corresponding adjacent APs from an AP in communication (S2). The moving vehicle measures the signal intensity from the AP in communication (S3). When the signal intensity becomes less than the given threshold (S4), the reception intensity values of signals sent from the respective adjacent AP are measured (S5). When some measured reception intensity is larger than the given threshold (S6), the moving vehicle changes its connection destination from the AP in communication to the adjacent AP having the maximum reception intensity (fast roaming) (S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile-vehicle operation control system, which uses a wireless communication system for communication between a plurality of repeaters connected to a management device and a mobile vehicle, and speeds up roaming by the communication. And a wireless communication method thereof.

[0002]

2. Description of the Related Art In an automobile assembly line, a system for controlling the operation of a moving vehicle that transports a vehicle body to be assembled is used.

[0003] A moving vehicle in the prior art is operated along a predetermined energized track. For power supply to mobile vehicles,
This is done by brush contact with the track.

[0004] Here, in an automobile assembly line,
The prior art mobile vehicle operation control system used in a completed vehicle assembly line for mounting parts such as seats, doors, interiors, and exteriors on a painted vehicle body is shown below.

First, in a completed car assembly line, different individual works are performed manually or by a work robot at a plurality of stations on a track of a moving car. At stations where work is performed manually,
Mobile vehicles run at a slow speed. In the station where the work is performed by the work robot, the moving vehicle stops in a state where the positioning is completely performed. The work by the work robot is performed with the moving vehicle stopped. Here, the work performed manually is generally a work of attaching small parts. The work performed by the work robot is generally a work of mounting a large component such as a door. Also, at each station, the height of the vehicle body being conveyed to the moving vehicle from the floor is automatically adjusted to the height at which workers can easily work or the height at which the work robot performs work. Is done.

[0006] Further, it has a management device for managing the entire system. The operation management of the mobile vehicle is performed through communication between the management device and the mobile vehicle. This communication is performed via a communication device provided in the mobile vehicle and a plurality of repeaters (access points: AP) connected to the management device.

Here, a fixed point communication system using optical communication for communication between a mobile vehicle and an AP has been mainly used. In recent years, a wireless communication system has been used for communication between a mobile vehicle and an AP. As a related invention using such a wireless communication system, Japanese Patent Application Laid-Open No. 7-95145 discloses an invention called "mobile vehicle operation control equipment". According to the present invention, communication states at all communication positions on the traveling route are
The purpose is to enable easy checking. The control means controls the running and controls the communication operation of the mobile communication device in a mobile vehicle provided with the mobile communication device for performing wireless communication with the ground communication device of the ground station. And a communication position detecting means for detecting a communication position for executing communication with the ground station side communication device, wherein the control means activates the mobile vehicle side communication device based on the detection result of the communication position detection means. In the operation control equipment, the mobile vehicle or the ground station is provided with communication state detecting means for detecting a communication state between the mobile vehicle communication device and the ground station side communication device, and the control unit is instructed to perform a communication test mode. Then, a test run that passes through all of the plurality of test communication positions is performed, and test communication with the ground station side communication device is performed at each of the plurality of test communication positions. This wireless communication can use a spread spectrum communication method.

In the mobile vehicle operation control system, when a wireless communication system is used for communication between the management device and the mobile vehicle,
It is desired that the communication be substantially uninterrupted.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mobile vehicle operation system capable of preventing the communication from being substantially interrupted when a wireless communication system is used for communication between the management device and the mobile vehicle. A control system and a wireless communication method thereof are provided.

Another object of the present invention is to perform wireless communication between a mobile vehicle and an AP when using a wireless communication system via a plurality of APs connected to the management device for communication between the management device and the mobile vehicle. Provided is a mobile vehicle operation control system and a wireless communication method that enable high-speed roaming.

Still another object of the present invention is to avoid a collision between mobile vehicles caused by a problem occurring in a running mobile vehicle when a wireless communication system is used for communication between the management device and the mobile vehicle, or The present invention provides a mobile vehicle operation control system and a wireless communication method that enable the reduction.

[0012]

According to the present invention, there is provided, in accordance with the present invention, a plurality of mobile vehicles, a plurality of repeaters connected to a management device, and performing wireless communication with the plurality of mobile vehicles, A management device having a repeater registration table in which adjacent repeater data indicating at least one adjacent repeater designated as a fast roaming destination is registered for each repeater; A communication unit for communicating with one communicating repeater, an acquiring unit for acquiring adjacent repeater data corresponding to the communicating repeater from the repeater registration table from the management device via the communication unit, When the reception strength of the signal transmitted from the repeater is less than the predetermined threshold, the communication partner is changed to the one having the highest reception strength among the adjacent repeaters indicated in the adjacent repeater data acquired by the acquisition unit. Change section To, to provide a mobile vehicle operation control system.

According to another aspect of the present invention, there is provided a vehicle comprising: a plurality of mobile vehicles; a management device; and a plurality of repeaters connected to the management device and performing wireless communication with the plurality of mobile vehicles. , Each repeater includes a repeater registration table in which neighboring repeater data indicating at least one neighboring repeater designated as a fast roaming destination is registered, and each mobile vehicle has one of a plurality of repeaters. A communication unit that communicates with the two communicating repeaters, an acquiring unit that acquires the corresponding adjacent repeater data from the repeater registration table of the communicating relay, and a reception intensity of a signal transmitted from the communicating repeater is predetermined. A change unit that changes the communication partner to the one having the highest reception strength among the adjacent repeaters indicated in the adjacent repeater data acquired by the acquisition unit when the threshold value is less than the threshold value. I will provide a

In the above-mentioned moving vehicle operation control system,
The management device has an input unit to which adjacent repeater data corresponding to each repeater is input, and a notification unit that notifies the input adjacent repeater data to each of the corresponding repeaters. The corresponding neighboring repeater data notified from the device can be stored in the corresponding repeater registration table.

Further, according to the present invention, in order to solve the above-mentioned problems, a plurality of mobile vehicles, a management device, and a plurality of repeaters connected to the management device and performing wireless communication with the plurality of mobile vehicles are provided. Each mobile vehicle includes, for each repeater, a repeater registration table in which adjacent repeater data indicating at least one adjacent repeater designated as a fast roaming destination is registered, and one of a plurality of repeaters. The communication unit that communicates with the communicating repeater, and the receiving repeater that is obtained by referring to the repeater registration table when the reception strength of the signal transmitted from the communicating repeater is less than a predetermined threshold. A mobile vehicle operation control system comprising: a changing unit that changes a communication partner to one having the highest reception strength among adjacent relays indicated by corresponding adjacent relay data.

In the above-mentioned mobile vehicle operation control system,
The management device has an input unit to which adjacent repeater data corresponding to each repeater is input, and a notification unit that notifies the input adjacent repeater data to a plurality of mobile vehicles via a plurality of repeaters, Each mobile vehicle can register the adjacent repeater data corresponding to each repeater notified from the management device in the repeater registration table.

In the above moving vehicle operation control system,
As the wireless communication, a spread spectrum communication based on a frequency hopping scheme can be used.

In the above moving vehicle operation control system,
The changing unit measures the reception strength of each signal emitted from the plurality of repeaters when the reception strength of the signal emitted from the adjacent repeater is less than the threshold, and is measured instead of the adjacent repeater. It may further comprise changing the communication partner to one repeater having the highest signal strength.

In addition, in order to solve the above-mentioned problems, according to the present invention, a plurality of mobile vehicles, a management device, and a plurality of repeaters connected to the management device and performing wireless communication with the plurality of mobile vehicles are provided. (A)
Registering, for each repeater, adjacent repeater data indicating at least one adjacent repeater designated as a fast roaming destination; and (b) determining whether the mobile vehicle is communicating with one of the plurality of repeaters during communication. Acquiring adjacent repeater data indicating an adjacent repeater corresponding to the communicating repeater; (c)
If the reception strength of the identification signal transmitted from the communicating repeater is less than a predetermined threshold, refer to the adjacent repeater data,
Measuring the reception strength of each signal emitted from the adjacent repeater corresponding to the communicating repeater;
There is provided a wireless communication method including a step of changing a communication partner to an adjacent repeater corresponding to a communicating repeater and having a maximum reception strength.

In the above wireless communication method, the wireless communication can use a frequency hopping type spread spectrum communication.

In the above radio communication method, the step (d) is performed when the reception intensity of each signal emitted from the adjacent repeater corresponding to the communicating relay measured in the step (c) is less than a threshold value. And the step of changing the communication partner to the one showing the maximum reception strength among the plurality of repeaters.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mobile vehicle operation control system according to the present invention will be described below with reference to the drawings. In the present embodiment, a mobile vehicle operation control system according to the present invention is applied to an automobile manufacturing line, in particular, an assembly line of a completed automobile.

FIG. 1 is a configuration diagram of an embodiment of a mobile vehicle operation management system according to the present invention.

Referring to FIG. 1, a mobile vehicle operation management system according to the present invention includes a management device 100, a plurality of repeaters (access points: AP) 200, and a predetermined track 400.
The vehicle includes a plurality of mobile vehicles 300 traveling thereon, a plurality of block controllers 410, and a plurality of stations 412 and 414 managed by each block controller 410.

The management device 100 is connected to a plurality of APs 200. The AP 200 and the mobile vehicle 300 perform wireless communication. The frequency hopping (FH) method of spread spectrum (SS) communication is applied to the wireless communication performed here. Using this wireless communication, the management device 100 manages the operation of the mobile vehicle 300.

The management device 100 is connected to a plurality of block controllers 410 and a plurality of stations 41 managed by each block controller 410.
2 and 414 are managed. Here, in each of the stations 412 and 414, a completed vehicle assembling process is performed on the transported object of the mobile vehicle 300 (the under-assembled vehicle 500) by a human or a robot.

Further, the management apparatus 100 includes an input / output unit 101
Having. By input from the input / output unit 101, it is possible to update management data for managing the mobile vehicle 300 and the stations 412 and 414 stored in the management device 100.

Repeater (access point: AP) 200
Can perform wireless communication with a plurality of mobile vehicles 300. The AP 200 can communicate with the mobile vehicle 300 when the mobile vehicle 300 exists in the corresponding cell area. Here, the cell area of the AP 200 is an area in which the strength of the transmission signal is equal to or higher than a predetermined threshold strength.

The arrangement of the plurality of APs 200 is based on AP2.
Communication between the mobile vehicle 300 and the management device 100 via the communication device 00 is always performed. At this time, the moving vehicle 300
Is included in at least one cell region. In addition, a plurality of AP2s are arranged such that an arbitrary location in a closed space (such as the entire automobile assembly line) where the mobile vehicle 300 exists is included in at least one cell area.
00 can also be arranged.

FIG. 2 shows an example of the arrangement of a plurality of APs in the mobile vehicle operation management system of the present invention. In this arrangement example,
Six APs 201, 202, 203, 204, 205,
206 is arranged.

The six APs 201, 202, 203, 20
4, 205 and 206 correspond to the corresponding cell areas 21 respectively.
1, 212, 213, 214, 215, 216,
An arbitrary location on a predetermined track 400 on which each mobile vehicle 300 moves is included in at least one cell area.
Each mobile vehicle 300 has a communication device 350, and performs wireless communication with one of the plurality of APs 200 using the communication device 350.

Each mobile vehicle 300 transports a vehicle 500 during assembly, which is a transported object. Further, each mobile vehicle 300 communicates with one of the plurality of APs 200 whose reception intensity is equal to or higher than a predetermined threshold.

Here, when the frequency hopping (FH) method of the spread spectrum (SS) communication is used for the wireless communication between the mobile vehicle 300 and the AP 200, each AP 200 transmits using a different hopping pattern. Therefore, the moving vehicle 30
0 indicates that when a transmission signal transmitted from one AP 200 is received, a transmission signal from another AP 200 does not substantially become noise. Therefore, the mobile vehicle 300 is
It is possible to individually identify and receive outgoing signals from 0. Therefore, even in the overlapping area where the cell area of the plurality of APs 200 overlaps, the mobile vehicle 300 is not
It is possible to communicate with one of the zeros.

The plurality of block controllers 410 manage the plurality of stations 412 and 414 according to the notification from the management device 100.

At the stations 412 and 414,
A predetermined completed vehicle assembly process is performed manually or by a robot.

According to the present embodiment, the management device 100
Host computer 110, host computer display device 111, backup computer 120, backup computer display device 121, data input / output computer 142, data input / output computer display device 144, block controller relay device 15
2, the first relay device 132, the second relay device 134, A
The P relay device 136 is provided.

The host computer 110 records a control algorithm for controlling the entire system, station control data in which data indicating the processes of the stations 412 and 414 are recorded, and data indicating the operation of the mobile vehicle 300. Mobile vehicle control data. The control algorithm includes a station control algorithm for controlling operations of the stations 412 and 414 and an AP control algorithm for controlling wireless communication between the AP 200 and the mobile vehicle 300. The station control data is transmitted to the plurality of block controllers 410 via the second relay device 134 and the block controller relay device 152. Each station 412, 414 is transmitted by the block controller 410 to which the station control data is transmitted.
Is controlled. The vehicle control data is stored in the second relay device 1
34 and the AP relay device 136 to the AP 200, and from the AP 200 to the mobile vehicle 300 by wireless communication.

Input / output of data to / from the host computer 110 is performed by a data input / output computer 142 connected via a first relay device 132. By the input from the data input / output computer 142, the above control algorithm and / or control data can be updated. Here, the data input / output computer 142 is connected to the data input / output computer display device 144, and causes the data input / output computer display device 144 to display information regarding data input / output to / from the host computer 110. It is possible.

The host computer 110 is connected to the display device 111 for the host computer, and can display various data managed by the host computer 110 on the display device 111 for the host computer.

The management device 100 is a host computer 1
It has at least one backup computer 120 as ten fault measures. The backup computer 120 has the same function as the host computer 110, and manages this system in place of the host computer 110 when a failure occurs in the host computer 110. Therefore, the backup computer 12
0 is also the same as the host computer 110, the second relay device 134 and the relay device 152 for the block controller.
Are connected to the plurality of block controllers 410 via the second relay device 134 and the AP 200 via the AP relay device 136, and are connected to the data input / output computer 142 via the first relay device 132. ing.

Each backup computer 120
Is connected to the backup computer display device 121, and can display various data managed by the backup computer 120 on the backup computer display device 121.

Further, a LAN using Ethernet is used for connection between the devices provided in the management device 100. According to the present embodiment, the host computer 110,
Backup computer 120, data input / output computer 142, block controller relay device 15
2, the first relay device 132, the second relay device 134, A
10 is required for the connection between the relay devices 136 and 138 for P.
0Base-TX is used. 10Base-T is used for connection between the AP relay device 136 and each AP.

FIG. 3 shows a functional block diagram of the repeater.

Referring to FIG. 3, each repeater (access point: AP) 200 includes a transmitting / receiving unit 220 capable of wirelessly communicating with a plurality of mobile vehicles 300, and an own AP 200.
And a high-speed roaming table 221 in which at least one AP 200 (adjacent AP) different from the above is registered. Here, as the adjacent AP registered in the high-speed roaming table 221, the one provided physically close to the own AP 200 is selected, and the number of adjacent APs to be registered is desirably four or less. Further, each AP 200 has a cell area that can communicate with the mobile vehicle 300.

Here, the high-speed roaming table 221 in the case of the example of the arrangement of a plurality of APs shown in FIG.
Shown in

[0046]

[Table 1]

FIG. 4 is a diagram showing a configuration of the mobile vehicle 300. Referring to FIG. 4, the mobile vehicle 300 includes a control unit 31.
0, drive device 320, rotation position sensor 330, lifter height adjustment device 340, communication device 350, distance sensor 366,
The power supply device 370 includes a plurality of wheels 380 and a bumper 390.

The control unit 310 controls the operation of the mobile vehicle, the height of the lifter, and communication with the management device 100. Control unit 3
10 includes a running distance detection unit 312, a memory 314 as a storage area, and a clock unit 315 for counting time.

The driving device 320 has an electric motor, and runs and steers the mobile vehicle 300 using the electric motor.

The rotation position sensor 330 generates a pulse proportional to the number of rotations (or rotation angle) of the electric motor of the driving device 320 for driving the wheels 380, and sends the pulse to the traveling distance detection unit 312 of the control unit 310. introduce. Also,
The rotation position sensor 330 can also generate a number of pulses proportional to the number of rotations (or rotation angle) of the wheels 380 and transmit the pulses to the traveling distance detection unit 312 of the control unit 310. The traveling distance detector 312 obtains the traveling distance of the mobile vehicle 300 based on the number of pulses transmitted from the rotation position sensor 330.

The lifter height adjusting device 340 is provided for the mobile vehicle 300.
Drives a lifter (not shown) for adjusting the height from the floor of a loading platform (not shown) for loading a transported object (car 500 during assembly). This lifter can change the height from the floor.

The communication device 350 performs wireless communication with one of the plurality of APs 200 connected to the management device 100 in order to communicate with the management device 100.

The distance sensor 366 is used to detect the moving vehicle 3 running immediately before.
It is a sensor for measuring the distance to 00, and is composed of an ultrasonic sensor. This distance sensor is used to maintain the tact (interval between the moving vehicles) with the moving vehicle 300 running immediately before.

The power supply device 370 is a device for supplying power to each device and sensor in the mobile vehicle 300, and obtains power by making contact with a powered rail.

A plurality of wheels 380 are provided, and the moving vehicle 300 moves as the wheels 380 rotate. The plurality of wheels 380 are composed of running wheels 381 and idle wheels 382, and the running wheels 381 are rotated and steered by the driving device 320.

The bumpers 390 are provided before and after the moving vehicle 300, and have a function of weakening an impact received by the moving vehicle 300 when the vehicle 300 comes into contact with or collides with another moving vehicle 300.

FIG. 5 is a functional block diagram of the communication device 350 of the mobile vehicle 300.

Referring to FIG. 5, communication apparatus 350 includes a transmitting / receiving section 351 capable of communicating with one of the plurality of APs 200, and a roaming control section 352 for controlling a roaming operation for changing the AP 200 with which the communication is performed.

The roaming control section 352 has a threshold value storage section 353 for storing the threshold value, and a high-speed roaming table 354 in which data of the high-speed roaming table 221 corresponding to the AP under communication is stored. here,
Threshold storage unit 353 and fast roaming table 354
May be secured in the memory 314 instead of in the communication device 350.

Next, the operation of the roaming control unit 352 is as follows.
Roaming is performed when the reception strength of the signal from the communicating AP 200 is less than a certain threshold. At this time, the roaming control unit 352 firstly transmits each AP stored in the high-speed roaming table 221 of the AP 200 being communicated with.
With 200 as a roaming destination candidate, each signal strength is acquired from each AP 200. Next, the roaming control unit 35
2 changes the communication destination to the AP 200 corresponding to the signal strength indicating the maximum and the threshold strength or more among the obtained signal strengths.

Next, a roaming method in the mobile vehicle operation control system of the present invention will be described below.

FIG. 6 is a flowchart showing a roaming method according to the present invention.

Referring to FIG. 6, first, for each AP 200, data indicating an adjacent or close AP 200 (hereinafter referred to as an adjacent AP) corresponds to a high-speed roaming table 2 corresponding thereto.
21 (step S1). The number of adjacent APs to be registered is four at the maximum in this embodiment. Here, as an AP adjacent to each AP 200, an AP whose physical distance is short,
It is desirable that an AP provided in the traveling direction of the mobile vehicle 300 is selected.

When the mobile vehicle 300 is communicating with one AP 200 (hereinafter referred to as a communicating AP), the communicating AP
Then, data indicating the corresponding adjacent AP is acquired from (step S2).

The mobile vehicle 300 measures the signal strength from the AP during communication (step S3). When the signal strength is less than the predetermined threshold value (step S4), the mobile vehicle 300 measures the reception strength of each signal emitted from each of the adjacent APs indicated by the data acquired from the AP during communication. (Step S5). If it is determined in step S4 that the signal strength is equal to or higher than the predetermined threshold, the process returns to step S4.
Return to step 3.

When each of the reception intensities measured in step S5 includes a value greater than or equal to a predetermined threshold value (step S6), the mobile vehicle 300 changes the connection destination from the AP that is communicating to the adjacent AP whose reception intensity is maximum. Change to (fast roaming)
(Step S7).

In addition, when each of the reception intensities measured in step S5 does not include a value equal to or greater than the predetermined threshold (step S6), the mobile vehicle 300 measures the reception intensity of each signal for all APs 200, The connection destination is changed from the communicating AP to the AP 200 whose reception strength is the highest (normal roaming) (step S8).

As a first modification of the mobile vehicle operation management system according to the present invention, each AP 200 does not have the high-speed roaming table 221 and the management device 100
May be stored. In this case, the roaming method of the mobile vehicle described above is changed as described below. First, step S1
With respect to each AP 200, the adjacent or close AP 2
00 (referred to as an adjacent AP) is stored in the management device 100
Will be recorded. Next, in step S2, when the mobile vehicle 300 is communicating with one AP 200 (referred to as a communicating AP), data indicating an adjacent AP corresponding to the communicating AP recorded in the management device 100 is transmitted to the communicating device. Acquired via the medium AP.

Next, as a second modification of the mobile vehicle operation management system according to the present invention, each AP 200 does not have the high-speed roaming table 221, and the adjacent AP corresponding to each AP is stored in the high-speed roaming table 354 of the mobile vehicle 300. A stored configuration is also possible. In this case, the roaming method of the mobile vehicle described above is changed as described below. First, steps S1 and S2 are not executed. In addition, in step S5, the mobile vehicle 300 searches the high-speed roaming table 354 to obtain data indicating the adjacent AP corresponding to the communicating AP, and obtains the signal of each signal emitted from each of the adjacent APs indicated by the data. Measure the reception strength.

The recording or change of the adjacent AP corresponding to each AP stored in the high-speed roaming table 354 is performed by the following operation. First, record data or change data indicating the record or change is input from the input / output unit 101 to the management device 100. Next, the management device 100 notifies the mobile vehicle 300 of the record data or the change data via the communicating AP. Lastly, the mobile AP 300 records the adjacent AP corresponding to each AP in the high-speed roaming table 354 or the high-speed roaming table 3 based on the notified recording data or change data.
The adjacent AP corresponding to each AP stored in 54 is changed.

In the above-described embodiments and modifications, the communication device 350 of the mobile vehicle 300 can perform an operation based on the signal-to-noise ratio of the signal instead of performing an operation based on the signal reception intensity.

As described above, the effects obtained by the mobile vehicle operation control system according to the present invention will be described below.

In the case of a mobile vehicle operation control system used for an automobile assembly line, during operation of the system,
A moving vehicle is moving between stations at regular intervals and at a constant speed. If this vehicle stops due to some malfunction, if control of the following vehicle is not performed,
Since the succeeding moving vehicle continues to travel, the moving vehicle collides with the succeeding moving vehicle. The way to avoid this collision is
It is necessary to perform an emergency stop for the entire moving vehicle.

In a mobile vehicle operation control system used when a management device and each mobile vehicle perform wireless communication over a wide area such as an automobile factory, the management device is connected to a plurality of repeaters (access points: AP). Then, wireless communication with each mobile vehicle is performed via the plurality of APs. In this case, each mobile vehicle communicates with the management device via one AP determined based on the measurement result of the intensity of each received radio wave from a plurality of APs. That is, each mobile vehicle communicates with the management device while switching the AP used for communication according to its own operation.

The switching (roaming) to the AP performed by the moving vehicle is performed as follows. If the communicating AP no longer satisfies the communicable condition, the communication device of the mobile vehicle searches for an AP having the highest reception intensity of the signal emitted from the existing APs, and the reception intensity of the signal from the AP is connected. If the condition is satisfied, switch to AP.

Here, the mobile vehicle cannot communicate (exchange information) with the management device during the AP switching operation. For this reason, when an emergency stop of another mobile vehicle is performed during an AP switching operation of a certain mobile vehicle, the transmission of a signal requesting an emergency stop from the management device to the mobile vehicle performing the AP switching operation is terminated by the AP switching operation. To be done later,
Signal transmission is delayed by the time required for the AP switching operation. In addition, when the mobile vehicle that has been emergency stopped is performing the AP switching operation, the transmission of the signal requesting the emergency stop of the mobile vehicle to the management device is performed after the AP switching operation is completed. The signal transmission is delayed by the minute.

According to the present invention, there is an effect that the speed of the AP switching operation can be increased by performing high-speed roaming of the moving vehicle with the change destination candidate limited to the AP switching operation. According to experiments by the inventor, the high-speed roaming operation in the mobile-vehicle operation control system according to the present invention is performed in several tens of milliseconds, at most less than one hundred milliseconds.

Here, the moving vehicle operation management system used by the inventor has a moving speed of 1.5 m / s, a distance from the preceding vehicle of 0.8 m, a weight of the moving vehicle of 1,400 kg, and a weight of the conveyed object. Is 1,400
Running at kg. Here, when a certain moving vehicle makes an emergency stop, if a signal requesting the following moving vehicle to make an emergency stop is not notified within approximately 500 ms from the time of the emergency stopping of a certain moving vehicle, the moving vehicle that has made an emergency stop and the subsequent moving vehicle A moving vehicle collides.

Here, in the mobile vehicle operation management system used by the inventor, emergency stop is performed for all mobile vehicles by the following method. (1) The mobile vehicle that has performed an emergency stop notifies the management device via the AP of a signal indicating the emergency stop.
(2) In response to the signal, the management device notifies all mobile vehicles of a signal requesting an emergency stop via the AP. (3) All moving vehicles perform an emergency stop. here,
In the communication between the mobile vehicle and the AP performed in the operations (1) and (2), it is necessary to perform AP switching by the mobile vehicle depending on the strength of a signal transmitted from the AP received by the mobile vehicle before the communication. There is. During the AP switching operation, communication between the mobile vehicle and the AP cannot be performed.

In the case of the mobile vehicle operation management system used by the inventor, when the switching time between the mobile vehicle and the AP is within 200 ms, a signal for requesting the subsequent mobile vehicle to perform an emergency stop is issued from the time of emergency stop of the mobile vehicle. Notification can be made within approximately 500 ms.

According to the experiment by the inventor, the high-speed roaming operation in the mobile vehicle operation control system according to the present invention is performed in several tens of milliseconds, at most less than 100 milliseconds. In addition, since an AP provided physically close to the communicating AP or / and provided in the traveling direction of the moving vehicle is selected as the change destination partner, the AP switching operation is not performed. Almost fast roaming is applied. From this, the mobile vehicle operation control system according to the present invention avoids collision between mobile vehicles caused by a problem occurring in a moving vehicle when using a wireless communication method for communication between the management device and the mobile vehicle. Or reduce it.

That is, the mobile vehicle operation control system according to the present invention can satisfy the signal transmission time required for maintaining the system stability in communication between the management device and the mobile vehicle. Wireless communication with the user can be substantially uninterrupted in time.

[0083]

The present invention has the effect of speeding up roaming between the mobile vehicle and the AP.

[Brief description of the drawings]

FIG. 1 shows a configuration of a mobile vehicle operation control system according to an embodiment of the present invention.

FIG. 2 shows an example of the arrangement of a plurality of APs in the mobile vehicle operation management system of the present invention.

FIG. 3 shows a functional block diagram of a repeater.

FIG. 4 shows a configuration of a mobile vehicle.

FIG. 5 shows a functional block diagram of a communication device of a mobile vehicle.

FIG. 6 is a flowchart illustrating a roaming method according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 management device 101 input / output unit 110 host computer 111 host computer display device 120 backup computer 121 backup computer display device 132 first relay device 134 second relay device 136 AP relay device 142 data input / output computer 144 data Input / output computer display device 152 Block controller relay device 200, 201, 202, 203, 204, 205, 2
06 repeater (AP) 211, 212, 213, 214, 215, 216 cell area 220 transmitting / receiving section 221 high-speed roaming table 300 moving vehicle 310 control section 312 mileage detecting section 314 memory 315 timer 320 drive device 330 rotation position sensor 340 lifter Height adjustment device 350 Communication device 351 Transmission / reception unit 352 Roaming control unit 353 Threshold storage unit 354 High speed roaming table 366 Distance sensor 370 Power supply device 380 Wheel 381 Running wheel 382 Idling wheel 390 Bumper 410 Block controller 412, 414 Station

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference)

Claims (10)

[Claims] 1. A plurality of mobile vehicles, a plurality of repeaters connected to a management device for performing wireless communication with the plurality of mobile vehicles, and at least one neighbor designated as a high-speed roaming destination for each of the repeaters The management device including a repeater registration table in which adjacent repeater data indicating a repeater is registered, wherein each of the mobile vehicles communicates with one of the plurality of repeaters during communication. A communication unit, an acquisition unit that acquires adjacent repeater data corresponding to the communicating repeater from the repeater registration table via the communication unit from the management device, and a signal transmitted from the communicating repeater. When the reception strength is less than a predetermined threshold, a change unit that changes the communication partner to the one showing the maximum reception strength among the adjacent repeaters indicated in the adjacent repeater data acquired by the acquisition unit. Do Mobile vehicle operation control system. 2. A mobile device comprising: a plurality of mobile vehicles; a management device; and a plurality of repeaters connected to the management device and performing wireless communication with the plurality of mobile vehicles, wherein each of the relay devices is designated as a high-speed roaming destination. And a repeater registration table in which neighboring repeater data indicating at least one neighboring repeater is registered, wherein each of the mobile vehicles communicates with one of the plurality of repeaters during communication. A communication unit, an acquisition unit that acquires corresponding adjacent repeater data from the repeater registration table of the communicating repeater, and a reception strength of a signal transmitted from the communicating repeater is less than a predetermined threshold. The mobile vehicle operation control system, further comprising: a change unit that changes a communication partner to one having the highest reception strength among the adjacent repeaters indicated in the adjacent repeater data acquired by the acquisition unit. 3. The management device, comprising: an input unit to which the adjacent repeater data corresponding to each of the repeaters is input; and a notification unit that notifies the input adjacent repeater data to each of the corresponding repeaters. The mobile vehicle operation control system according to claim 2, wherein each of the repeaters stores the corresponding adjacent repeater data notified from the management device in the corresponding repeater registration table. 4. 4. A vehicle comprising: a plurality of mobile vehicles; a management device; and a plurality of repeaters connected to the management device and configured to perform wireless communication with the plurality of mobile vehicles. A repeater registration table in which adjacent repeater data indicating at least one adjacent repeater designated as a fast roaming destination is registered; and a communication unit that communicates with one of the plurality of repeaters during communication. And, if the reception strength of the signal transmitted from the communicating repeater is less than a predetermined threshold, the adjacent repeater data corresponding to the communicating repeater obtained by referring to the repeater registration table. A change unit for changing the communication partner to the one showing the maximum reception strength among the adjacent repeaters shown, the mobile vehicle operation control system. 5. The management device, comprising: an input unit to which adjacent repeater data corresponding to each of the repeaters is input; and the plurality of mobile units transferring the input adjacent repeater data via the plurality of repeaters. The mobile device according to claim 4, further comprising a notification unit configured to notify a vehicle, wherein each of the mobile vehicles registers adjacent relay device data corresponding to each of the relay devices, notified from the management device, in the relay device registration table. Mobile vehicle operation control system. 6. The mobile vehicle operation control system according to claim 1, wherein the wireless communication uses a spread spectrum communication of a frequency hopping method. 7. The receiving device according to claim 6, wherein the receiving unit measures the reception intensity of each signal transmitted from the plurality of relays when the reception intensity of the signal transmitted from the adjacent relay is less than the threshold. The mobile vehicle operation control according to any one of claims 1 to 6, further comprising changing a communication partner to one repeater having the maximum measured signal strength instead of the adjacent repeater. system. 8. A mobile vehicle operation control system comprising a plurality of mobile vehicles, a management device, and a plurality of repeaters connected to the management device and performing wireless communication with the plurality of mobile vehicles, wherein: Registering, for each repeater, neighboring repeater data indicating at least one neighboring repeater designated as a fast roaming destination; and (b) the mobile vehicle is communicating among the plurality of repeaters. Acquiring adjacent repeater data indicating an adjacent repeater corresponding to one communicating repeater; and (c) receiving strength of the identification signal transmitted from the communicating repeater is less than a predetermined threshold value. Measuring the reception strength of each signal transmitted from the adjacent repeater corresponding to the communicating repeater with reference to the adjacent repeater data; and Compatible with vessels Wherein of the adjacent repeaters, comprising the step of changing the communication partner to show the maximum reception strength, the wireless communication method that. 9. The wireless communication method according to claim 8, wherein the wireless communication uses a spread spectrum communication of a frequency hopping method. 10. The method as claimed in claim 10, wherein the step (d) comprises: when a reception strength of each signal emitted from the adjacent repeater corresponding to the communicating repeater measured in the step (c) is less than the threshold value; The wireless communication method according to claim 8, further comprising a step of changing a communication partner to one having a maximum reception strength among the plurality of repeaters.