JP2016154283A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read a response signal from a radio communication device installed in an object at a higher speed.SOLUTION: A radio communication system is a radio communication system including a radio communication device capable of responding sensing information obtained by converting an analog amount detected by a sensor into digital data through a radio communication command, and a reader for communicating with the radio communication device includes, as the radio communication device, n kinds of radio communication devices for responding to mutually different commands (n is a natural number), and, as the reader, n kinds of readers capable of transmitting commands respectively corresponding to the n kinds of radio communication devices. The n kinds of radio communication devices are installed in objects from the first to the n-th radio communication devices at prescribed intervals in turn and repeatedly, and the n kinds of readers are installed in mobile objects movable along the objects from the first to the n-th readers in prescribed intervals in turn and repeatedly.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication system.

  RFID (Radio Frequency Identification) tags, non-contact IC cards, and the like are generally known as wireless communication devices that perform non-contact communication with an external reading device via electromagnetic waves. These wireless communication devices can write or read data in response to a command request by transmitting or receiving a command from the reading device via an electromagnetic wave.

In general, an RFID tag can read less information than a non-contact IC card or the like, but more than a bar code. Among them, UHF (Ultra High Frequency) band RFID tags can be read simultaneously even at a distance of several meters. There are advantages, and it is widely used in products, people management, logistics, medical, architecture, transportation, etc.
When reading data from RFID tags, generally in the logistics field, etc., a relatively slow speed, such as when a reading device is installed at a predetermined location and an RFID tag placed on a package transported by a belt conveyor is read. Often used in. However, in the transportation field such as railways and automobiles, at least one of the RFID and the reading device may be installed on a moving body and used at a relatively high speed. For example, there is a system in which RFID tags are used for managing train train car numbers. In this system, an RFID tag is attached to a vehicle, and a reading device is installed between stations, at a yard, a large freight transportation center, and the like, and information on trains and vehicles in operation is identified.

  In recent years, an RFID tag that incorporates a sensor function in such an RFID tag has been proposed. This incorporates a sensor function for sensing environmental changes in an RFID tag, and reads sensing information from an external reader. An RFID tag incorporating such a sensor function has been studied for application in various fields, and in particular, its application in the above-described transportation field has attracted attention. For example, when managing the deterioration of the track by monitoring railway track distortion and temperature changes, or by embedding an RFID tag with a built-in temperature sensor in the concrete of the tunnel inner wall and managing the temperature, Deterioration state may be managed. In either case, the RFID tag is embedded in the maintenance management target, and the mobile RFID tag is read while the mobile body in which the reader is installed is used at a relatively high speed. In these cases, it is possible to improve the efficiency of maintenance work by reading the RFID tag at a higher speed.

  As a method of reading the RFID tag at such a relatively high speed, for example, a reading device that transmits an activation signal is installed in front of the moving body, and a reading device that receives a response signal from the tag is placed behind the moving body. A method for extending the allowable response time in the tag and collecting the measurement data to be maintained is disclosed (for example, Patent Document 1).

JP 2012-084064 A

  However, the method disclosed in Patent Document 1 is effective up to a certain level of the speed of the moving body, but when the speed further increases, the time allowed for reading the RFID tag is shortened, and the reading is eventually performed. If the required time is less than the required time, necessary information cannot be obtained from the object (for example, maintenance management target).

  SUMMARY An advantage of some aspects of the invention is that it provides a wireless communication system capable of reading a response signal from a wireless communication device installed on an object at higher speed.

  One embodiment of the present invention includes a wireless communication device capable of responding to sensing information obtained by converting an analog amount detected by a sensor into digital data via a wireless communication command, and a reading device for communicating with the wireless communication device. The wireless communication device includes n types of wireless communication devices that respond to different commands as the wireless communication device (n is a natural number), and each of the n types of wireless communication devices serves as the reading device. N kinds of reading devices capable of transmitting a corresponding command, wherein the n kinds of wireless communication devices are arranged on a target object in order of the first to nth wireless communication devices in order and repeatedly at predetermined intervals. In the type of reading device, first to n-th reading devices are sequentially and repeatedly installed at predetermined intervals on a movable body that can move along the object. And which is a wireless communication system.

  Further, according to one embodiment of the present invention, in the wireless communication system, each of the n types of reading devices is spaced from a reading device installed adjacent to the n types of wireless communication devices by a distance greater than a reading range. It is installed on the moving body.

  In addition, according to another aspect of the present invention, in the wireless communication system, the n types of reading devices can each correspond to wireless communication via corresponding commands when the moving body moves along the object. The sensing information is received from a communication device.

  According to one embodiment of the present invention, in the wireless communication system, a passive UHF (Ultra High Frequency) band RFID (Radio Frequency IDentifier) including the sensor is used as the wireless communication device.

  One embodiment of the present invention is the above wireless communication system, wherein the wireless communication device includes a temperature sensor as the sensor.

  In addition, according to another aspect of the present invention, in the wireless communication system, the n types of reading devices can each correspond to wireless communication via corresponding commands when the moving body moves along the object. The sensing information obtained by converting the analog quantity detected by the temperature sensor into digital data is received from the communication device.

  One embodiment of the present invention is the above wireless communication system, wherein the wireless communication device includes a strain sensor or a vibration sensor as the sensor.

  In addition, according to another aspect of the present invention, in the wireless communication system, the n types of reading devices can each correspond to wireless communication via corresponding commands when the moving body moves along the object. The sensing information obtained by converting the analog quantity detected by the strain sensor or the vibration sensor into digital data is received from a communication device.

  ADVANTAGE OF THE INVENTION According to this invention, the response signal from the radio | wireless communication apparatus installed in the target object can be read more rapidly.

It is explanatory drawing of an example of a structure of the radio | wireless communications system which concerns on 1st Embodiment. It is a detailed explanatory view of a configuration of a wireless communication system according to the first embodiment. It is a conceptual diagram of the polling waveform transmitted from a reader. It is a conceptual diagram of the state of RF carrier which a radio | wireless communication apparatus receives. It is a figure which shows the relationship between the antenna characteristic of a reader, and a communication range. It is the figure which showed the advancing direction of the electromagnetic wave of a circularly polarized wave and a linearly polarized wave. It is a conceptual diagram of command communication between a reading device and a wireless communication device. It is explanatory drawing of the usage example of the radio | wireless communications system which concerns on 3rd Embodiment. It is explanatory drawing of the usage example of the radio | wireless communications system which concerns on 4th Embodiment.

  First, the problems of the prior art will be specifically described. For example, the method disclosed in Patent Document 1 is effective up to a certain level of the speed of the moving object, but when the speed further increases, the time allowed for reading the RFID tag is shortened, and the reading is eventually performed. If the required time is less than the required time, the necessary information cannot be obtained from the maintenance management target.

When at least one of the reading device and the RFID tag is installed on the moving body and the reading is performed dynamically, the reading range of the reading device is L [m], the speed of the moving body is V [km / h], When the reading time allowed for the RFID tag is t [sec], these relationships are expressed by the following (formula 1).
t = 3.6 × L / V [sec] (Equation 1)

  For example, when L = 1 m and V = 60 km / h and calculation is performed using the above (Equation 1), the read time t allowed for the RFID tag is 60 ms (t = 3.6 × 1/60 = 0.06 [sec] = 60 [ms]).

  However, in order to complete reading at least once within the reading time t allowed for the RFID tag regardless of the communication timing, the reading period of the RFID tag needs to be less than half of the time t. is there. Note that the RFID tag can be read more stably and surely as the number of times the RFID tag can be read within a predetermined time is increased in consideration of a case where a communication error occurs.

Therefore, when the number of times of reading within a predetermined reading time is N, the RFID tag reading cycle T is expressed by the following (Equation 2).
T = (3.6 / (N + 1)) × (L / V) [sec] (Expression 2)

  For example, assuming that N = 1, L = 1 m, and V = 60 km / h and calculating using the above (Equation 2), the read cycle T allowed for the RFID tag is 30 ms (T = (3. 6/2) × (1/60) = 30 [ms]). That is, when a mobile body equipped with a reading device having a communication range of 1 m passes through an RFID tag at a speed of 60 km / h, a reading cycle for completing at least one reading within a predetermined time. Is 30 ms or less.

  In recent years, a maintenance management system using a system using an RFID tag with a built-in sensor function has been studied. For example, a system that manages the deterioration of the track by monitoring strain and temperature changes in the railway track, or an RFID tag with a built-in temperature sensor in the concrete on the tunnel inner wall, and the concrete is managed by controlling the temperature. A system for managing the deterioration state of the slag is being studied. In any of these methods, a maintenance vehicle equipped with a reading device is run, and sensing information is collected from RFID tags installed at various locations while the vehicle is running, thereby managing a deterioration state of a maintenance management target.

  However, when RFID tags equipped with such a sensor function start to be introduced, the number of maintenance management targets increases, and therefore, reading at a higher speed is required for the efficiency of maintenance management work. In order to read the RFID tag at a higher speed, it is conceivable to lengthen the communication range L or shorten the RFID tag reading cycle T in the above (Formula 2).

  A general RFID tag can read a plurality of RFID tags at the same time, but since command communication is performed serially, the more RFID tags that are read simultaneously, the longer the time required for command communication. For this reason, in such mobile communication, it is necessary to shorten the command processing time by setting only the selected RFID tag to be read. However, the RFID tag read cycle T depends on the processing capability of the reading apparatus as well as the command processing time. For this reason, it is difficult to shorten it to a certain time (for example, several ms) or less due to the limitations of the processing time and processing capacity.

As a countermeasure against this, it is conceivable to lengthen the communication range L and increase the read time t allowed for the RFID tag. As a measure for increasing the communication range L, it is conceivable to use a UHF band having a relatively long communication distance among RFID tags. In the RFID tag of the UHF band, communication is generally possible at 3 to 5 m.
For example, assuming that N = 1, L = 5 m, and V = 60 km / h and calculating using the above (Equation 2), the read cycle T allowed for the RFID tag is 150 msec (T = (3. 6/2) × (5/60) = 150 [ms]).

Here, the speed of the movable body that can be handled with respect to the read cycle T is expressed by the following (formula 3).
V = (3.6 / (N + 1)) × (L / T) [sec] (Equation 3)
Assuming that the read cycle T is 30 ms, the speed V of the movable body that can be handled is 300 km / h according to (Equation 3) (V = (3.6 / 2) × (5/0. 03) = 300 [km / h]).

  However, there is no problem when there is only one RFID tag installed in the maintenance management target within the communication range of the reading device, but when there are a plurality of RFID tags, a desired RFID is included in the communication command from the reading device. There is a problem that other than tags will respond. When a plurality of RFID tags respond in a single reading setting state, a plurality of RFID tags respond simultaneously to one command, so that a collision occurs, and as a result, even one sheet cannot be read. . Therefore, when installing the RFID tag, it is necessary to leave an interval larger than the reading range of the reading device, and there is a problem that fine management is not possible.

  For example, when managing the concrete state of the inner wall of a tunnel more finely, it is necessary to install RFID tags at intervals of about 1 m. In this case, if the communication range L of the reading device is 5 m, a plurality of RFID tags will respond simultaneously, so the communication range of the reading device must be set narrow. However, if the operating range of the reading device is 1 m, the interval between RFID tags can be shortened, but the allowable reading time t is also shortened, which makes it difficult to read at high speed.

Therefore, in the wireless communication device according to the present embodiment, even if the interval between the wireless communication devices installed on the maintenance management target (an example of the target object) is shortened, it does not interfere with neighboring wireless communication devices, and the moving body Sensing information can be obtained from each wireless communication device even when traveling at high speed.
Hereinafter, this embodiment will be described with reference to the drawings. Note that the permissible read time t is also referred to as “allowable read time t” in the following description.

[Overview of this embodiment]
First, an outline of the present embodiment will be described. The wireless communication system according to the present embodiment reads sensing information obtained by converting an analog amount detected by a sensor into digital data, and a wireless communication device capable of responding via a wireless communication command to communicate with the wireless communication device. Device. As wireless communication devices, n types of wireless communication devices that respond to mutually different commands are provided (n is a natural number). Further, as reading devices, n types of reading devices capable of transmitting commands corresponding to the n types of wireless communication devices are provided. In the n types of wireless communication devices, the first to n-th wireless communication devices are sequentially and repeatedly installed at maintenance management targets at predetermined intervals. On the other hand, n types of reading devices are sequentially and repeatedly installed at predetermined intervals on a movable body that can move along a maintenance management target.

  Then, the n types of reading devices installed in the mobile body receive sensing information from the corresponding wireless communication devices via the corresponding commands as the mobile body moves along the maintenance management target. Thereby, a mobile body can collect sensing information at high speed without interfering with adjacent wireless communication apparatuses.

For example, the first wireless communication apparatus is set in advance to respond only to the command 1 from the first reading apparatus. For this reason, there is no response to a command transmitted from a reading device other than the first reading device. Similarly, the nth wireless communication device is set in advance to respond only to the command n from the nth reading device. For this reason, there is no response to a command transmitted from a reading device other than the nth reading device.
In addition, for example, each of the n types of reading devices is installed on the moving body with an interval equal to or greater than the reading range for the n types of wireless communication devices.

  In such a configuration, when the first reading device installed in the mobile body transmits the command 1 to all of the plurality of wireless communication devices within the communication range, only the first wireless communication device responds. Therefore, only the information of the first wireless communication device can be collected from the plurality of wireless communication devices. That is, when the nth reading device installed in the mobile body transmits a command n to all of the plurality of wireless communication devices within the communication range, only the nth wireless communication device returns a response. Only information on the nth wireless communication device can be collected from the plurality of wireless communication devices.

  Therefore, even if there are n types of wireless communication devices within the communication range of the reading device, only information on the desired wireless communication device can be reliably read. Further, the speed of the moving body can be further increased by adjusting the antenna characteristics and output of the reader to widen the communication range and increasing the value of n accordingly.

Here, the relationship between the value of n and the communication range of the reading device will be described.
When n types of wireless communication devices are installed as maintenance management targets, it is necessary to determine the value of n depending on the communication range of the reading device. The relationship between the value of n and the communication range L [m] of the reading device is expressed by the following (Equation 4), where the arrangement interval of the wireless communication devices is Dt [m].
n = L / Dt (Formula 4)

For example, when wireless communication devices are arranged at 1 m intervals with respect to a reading device having a communication range L of 5 m, n = 5/1 = 5. However, the value of n is a natural number and must be rounded up when the upper end of the calculation is obtained. Therefore, in the case of this example, by setting the value of n to at least 5 or more, while setting the communication range L to 5 m, the information on the desired wireless communication device without interfering with neighboring wireless communication devices. Only you can get for sure.
Hereinafter, the wireless communication system according to the present embodiment will be specifically described with reference to the drawings.

[First embodiment]
FIG. 1 is an explanatory diagram of an example of the configuration of the wireless communication system according to the present embodiment. The wireless communication system 100 includes a wireless communication device 2j (j = 1 to n) installed in the maintenance management target 300 and a reading device 4j (j = 1 to n) installed in the mobile body 200. The maintenance management object 300 shown in this figure is, for example, concrete on the inner wall of a railway tunnel. A moving body 200 (for example, a vehicle) travels in the maintenance management target 300. The traveling direction of the moving body 200 is the longitudinal direction of the tunnel (the traveling direction may be forward or reverse), and is indicated by an arrow 90.

  In the maintenance management object 300, n types of wireless communication devices 2j that can convert an analog amount detected by the sensor into digital data and respond via different wireless communication commands are embedded. Specifically, the maintenance management target 300 includes wireless communication devices 2j in order from the wireless communication device 21 to the wireless communication device 2n at predetermined intervals along the longitudinal direction of the tunnel (the direction of the arrow 90), and , Buried side by side repeatedly. For example, the wireless communication device 2j is embedded in the maintenance management target 300 at an arbitrary interval necessary for management.

  The mobile body 200 is provided with n types of reading devices 4j for reading information of the wireless communication device 2j. Specifically, on both side surfaces of the moving body 200 facing the maintenance management target 300, the reading device 41 to the reading device 4n are spaced at predetermined intervals along the traveling direction of the moving body 200 (the direction of the arrow 90). It is installed in order and repeatedly. For example, the reading device 4j is arranged at a certain interval so that the communication range does not overlap with the reading device 4j on both sides. The communication range of the reading device 4j is set according to the distance between the wireless communication device 2j and the reading device 4j and the value of n.

  Here, each of the n types of reading devices 4j can transmit a command corresponding to each of the n types of wireless communication devices capable of responding to different wireless communication commands. That is, the reading device 4n transmits a wireless communication command to which only the wireless communication device 2n can respond, and receives sensing information from only the wireless communication device 2n. That is, the reading device 4n can communicate only with the wireless communication device 2n.

The communication range of the reading device 4j will be described with reference to FIG.
FIG. 2 is a detailed explanatory diagram of the configuration of the wireless communication system according to the present embodiment. This figure is shown in detail as a configuration example in the case where n is 4 in FIG. In the configuration shown in this figure, four types of wireless communication devices 2j, that is, the wireless communication device 21 to the wireless communication device 24, are embedded in the maintenance management object 300 in order and repeatedly at an arrangement interval Dt [m]. The mobile body 200 is provided with four types of reading devices 4j from the reading device 41 to the reading device 44. In addition, a part is omitted and illustrated.

  In this figure, when the mobile body 200 travels within the maintenance management target 300, the distance between the reading device 4j installed in the mobile body 200 and the wireless communication device 2j embedded in the maintenance management target 300 is the distance It is assumed that d [m]. A communication range L [m] of the reading device 4j indicates a range in which communication is possible at a position separated from the wireless communication device 2j by a distance d [m].

Here, while the mobile unit 200 passes at a speed V [km / h] next to the maintenance management target 300 in which the wireless communication device 2j having the read cycle T is embedded, at least once from each wireless communication device 2j. When acquiring the above information, the communication range L required for the reading device 4j can be expressed by (Expression 5) obtained by modifying (Expression 3) described above.
L = V × T × ((N + 1) /3.6) [m] (Formula 5)
Here, assuming that V = 240 km / h and T = 0.03 sec, L = 240 × 0.03 × (2 / 3.6) = 4 [m], and the communication range L is 4 m or more. It turns out that it is good to adjust to.

The relationship between the communication ranges L and n and the interval Dt is expressed by the following (formula 6).
Dt = L / n [m] (Expression 6)
Here, when L is 4 m and n is 4, Dt = 4/4 = 1 [m], and it is understood that the interval Dt at which the wireless communication device 2 j is installed should be set to 1 m or more.
When n is 5, Dt = 4/5 = 0.8 [m]. When n is 8, Dt = 4/8 = 0.5 [m]. By increasing n, Regardless of the speed of the moving body 200, the interval Dt between the wireless communication devices 2j can be reduced. In addition, the arrangement interval Dr [m] of the reading device 4j in the moving body 200 is, for example, an interval that is greater than or equal to the reading range for the wireless communication device 2j, that is, an interval that is greater than or equal to the communication range L. For example, when L is 4 m, the arrangement interval Dr of the reading device 4 j is set to 4 m or more. The arrangement interval Dr is not limited to the communication range L or more, but may be an interval less than the communication range L.

  In the state shown in this figure, the reading device 41 is connected to the wireless communication device 21 among the wireless communication device 24, the wireless communication device 21, the wireless communication device 22, and the wireless communication device 23 within the communication range L of itself. Only communicate. Further, the reading device 42 performs communication only with the wireless communication device 22 among the wireless communication device 24, the wireless communication device 21, the wireless communication device 22, and the wireless communication device 23 that are within the communication range L of the reading device 42.

Next, the relationship between the allowable read time t and the read cycle T will be described with reference to FIGS.
FIG. 3 is a conceptual diagram of a polling waveform transmitted from the reading device 4j. Normally, when the reading device 4j transits from the RF carrier OFF state to the ON state, the reading device 4j transmits a wireless communication command to the wireless communication device 2j. When the wireless communication device 2j that responds to this wireless communication command does not exist in the vicinity, the reading device 4j transitions the RF carrier to the OFF state. The OFF period of the RF carrier is also a reset signal to the wireless communication device 2j. When the reading device 4j changes to OFF for a certain period, the reading device 4j changes to the ON state again and transmits a wireless communication command. A state in which this is repeated is generally called polling.

FIG. 4 is a conceptual diagram of the state of the RF carrier received by the wireless communication device 2j when the polling reading device 4j and the wireless communication device 2j communicate with each other dynamically. When the reading device 4j and the wireless communication device 2j communicate with each other while dynamically passing, the RF carrier received by the wireless communication device 2j changes according to the passing timing. Therefore, in order to correctly read information from the wireless communication device 2j, at least one RF carrier OFF period and a command communication period, that is, a reading cycle T are required.
Therefore, in order to perform reading at least once within the allowable reading time t regardless of the passing timing, it is necessary to set the reading cycle T to half or less of the allowable reading time t.

Next, the communication range L of the reading device 4j and the distance d from the wireless communication device 2j will be described. The communication range L of the reading device 4j indicates the communication range of the wireless communication device 2j at a position away from the antenna (not shown) surface of the reading device 4j by a distance d.
FIG. 5 is a diagram illustrating a relationship between the antenna characteristic of the reading device 4j and the communication range L. For the RF carrier output from the reading device 4j, when it is desired to shorten the distance d and set the communication range L large, or when the communication range L is decreased and the distance d is increased, the antenna output of the reading device 4j is adjusted. Each can respond.

  For example, with respect to the RF carrier output from the reading device 4j, when it is desired to set the communication range L large by shortening the distance d, it is possible to cope with it by using circular polarization. Further, when it is desired to reduce the communication range L and increase the distance d, it is possible to cope with it by using linearly polarized waves.

  FIG. 6 is a diagram showing the traveling directions of radio waves of circular polarization and linear polarization. In general, circularly polarized waves do not depend on the antenna direction of the wireless communication device 2j because radio waves propagate while rotating. In the case of circular polarization, long-distance communication is difficult, but the communication range in the vicinity can be widened. On the other hand, since linearly polarized waves propagate while radio waves vibrate linearly, depending on the direction of the antenna of the wireless communication device 2j, the communication distance can be increased by matching the directions.

  Next, command communication between the reading device 4j and the wireless communication device 2j will be described with reference to FIG. FIG. 7 is a conceptual diagram of command communication between the reading device 4j and the wireless communication device 2j. Here, command communication with n types of wireless communication devices 2j is shown by taking the reading device 43 (that is, j = 3) as an example. The reading device 43 transmits a command 3 that can be responded to only by the wireless communication device 23 (that is, j = 3) as a wireless communication command. Thereby, only the wireless communication device 23 responds to the command 3 transmitted from the reading device 43 and communication is established. The wireless communication device 2j other than the wireless communication device 23 does not respond to the command 3 transmitted from the reading device 43.

[Second Embodiment]
In this embodiment, a passive UHF band RFID tag with a built-in sensor is used as the wireless communication device 2j described in the first embodiment.
For example, the wireless communication device 2j is a UHF band RFID tag that converts an analog amount detected by a sensor into digital data and can respond via a wireless communication command. Specifically, the n types of wireless communication devices 2j are n types of RFID tags that respond only to predetermined wireless communication commands. The reading device 4j is a reading device for communicating with the RFID tag. For example, the n types of reading devices 4j are n types of reading devices capable of transmitting wireless communication commands respectively corresponding to the n types of RFID tags.

  Further, n types of RFID tags as n types of wireless communication devices 2 j are embedded in the maintenance management target 300. For example, as described in the first embodiment, the maintenance management target 300 includes n types of RFID tags in order at predetermined intervals along the longitudinal direction of the tunnel (the direction of the arrow 90), and It is buried side by side repeatedly.

  On the other hand, n types of reading devices 4 j are installed in the moving body 200. For example, as described in the first embodiment, predetermined distances are provided on both side surfaces of the moving body 200 facing the maintenance management target 300 along the traveling direction of the moving body 200 (the direction of the arrow 90). In order and repeatedly. Further, the reading device 4j is arranged at a certain interval so that the communication range does not overlap with the reading device 4j on both sides.

  According to the present embodiment configured as described above, n types of reading devices 4j installed in the moving body 200 receive sensing information from a desired RFID tag via n types of corresponding wireless communication commands. By doing so, the mobile body 200 can collect sensing information at high speed without interfering with adjacent RFID tags.

[Third Embodiment]
The present embodiment is an example in which a wireless communication device 2j provided with a temperature sensor is used as the wireless communication device 2j described in the first embodiment. For example, the wireless communication device 2j has a built-in temperature sensor. In this case, the frequency used for communication may be any of the LF band (30 kHz to 300 kHz), the HF band (3 MHz to 30 MHz, the UHF band (300 MHz to 3 GHz), and the wireless communication device 2j is active even if it is a passive type. In particular, in the case of a system using a plurality of sensors, it is preferable to use a semi-passive type that supplies external power only to the sensor circuit unit in order to supplement the power supplied to the sensors.

  Here, with reference to FIG. 8, the usage example of this embodiment is demonstrated. FIG. 8 is an explanatory diagram of a usage example of the wireless communication system according to the present embodiment. This figure shows, for example, a usage example in the case where the maintenance object 300 is the inner wall concrete of the tunnel 5 and the deterioration state of the inner wall concrete is managed using the wireless communication device 2j with a built-in temperature sensor. is there. (A) has shown the tunnel 5 of a railway, and the inner wall concrete of the side wall of the tunnel 5 which is the maintenance management object 300. FIG. (B) shows the moving body 200 (vehicle) passing through the tunnel 5. In the moving body 200, a plurality of reading devices 4j (j = 1 to n) are arranged side by side as in FIG.

  (C) is an enlarged view of the inner wall concrete which is the maintenance management target 300. Reinforcing bars are embedded in the inner wall concrete that is the object of maintenance management 300, and a plurality of wireless communication devices 2j (j = 1 to n) are installed or buried side by side in the same manner as in FIG. 1 near the surface of the inner wall. Yes. Reinforcing bars embedded in the inner wall concrete are corroded due to the penetration of oxygen and moisture into the concrete. In (c), normal reinforcing bars 7 and corroded reinforcing bars 8 are shown as the embedded reinforcing bars. Further, (d) shows a cross section of a normal rebar 7, and (e) shows a cross section of a corroded rebar 8.

  In this embodiment, a current is applied to the reinforcing bars embedded in the inner wall concrete, and the temperature sensor is used to calculate the difference between the surface temperature of the inner wall concrete when the reinforcing bars are forcibly heated and the surface temperature when the reinforcing bars are not heated. By measuring, the deterioration state of the inner wall concrete is determined. This utilizes the property that, when the reinforcing bar is corroded, a corrosive layer is formed between the reinforcing bar and the concrete and the thermal conductivity is deteriorated, so that the temperature difference between heating and non-heating becomes small.

  For example, the wireless communication device 2j with a built-in temperature sensor is embedded in the surface layer of the inner wall concrete, and the reading device 4j periodically acquires and monitors the temperature information in the unheated state and the temperature information in the heated state. It becomes possible to diagnose the deterioration state.

  For example, when such maintenance management is performed in a railway tunnel 5, n types of wireless communication devices 2 j with a built-in temperature sensor are embedded in the surface layer portion of the inner wall concrete of the tunnel 5, and the mobile body 200 also has n types of readings. The apparatus 4j is installed. The n types of reading devices 4j digitally convert analog amounts detected by the temperature sensors from the corresponding wireless communication devices 2j via the corresponding wireless communication commands as the moving body 200 moves along the inner wall concrete. Receives sensing information converted into data. As a result, the temperature data can be collected every time the moving body 200 passes through the tunnel 5. Moreover, it is preferable to determine the timing and heating interval for heating the reinforcing bars as necessary in operation. Note that the interval Dt at which the wireless communication device 2j is installed is set based on the communication range L of the reading device 4j and the speed V of the moving body 200 as described above. By analyzing the temperature data of the inner wall concrete collected by the reading device 4j in this way, it becomes possible to discover a deterioration state of a specific portion of the inner wall concrete at an early stage.

[Fourth Embodiment]
The present embodiment is an example in which a wireless communication device 2j provided with a strain sensor or a vibration sensor is used as the wireless communication device 2j described in the first embodiment. For example, the wireless communication device 2j includes a strain sensor or a vibration sensor. Note that the temperature sensor described in the third embodiment and the strain sensor or vibration sensor of the present embodiment may be incorporated in one wireless communication device 2j. Moreover, it is preferable that the wireless communication device 2j of the present embodiment also uses a semi-passive type as in the third embodiment.

  Here, with reference to FIG. 9, the usage example of this embodiment is demonstrated. FIG. 9 is an explanatory diagram of a usage example of the wireless communication system according to the present embodiment. In this figure, the maintenance management object 300 is a concrete block of a railway bridge 10, and the joint portion 11 of the concrete block or the concrete block existing for each bridge girder 12 using a wireless communication device 2j incorporating a strain sensor or a vibration sensor. The usage example in managing a transition is shown with the schematic diagram.

  In the concrete block of the bridge 10, a plurality of wireless communication devices 2j incorporating strain sensors or vibration sensors are installed side by side as in FIG. For example, the wireless communication device 2j is installed in a joint portion 11 between adjacent concrete blocks for each bridge girder 12 and a concrete block between adjacent bridge girders 12 (that is, a concrete block other than the joint portion 11). In the moving body 200 (vehicle) that can travel on the bridge 10, a plurality of reading devices 4j are installed side by side as in FIG. Some descriptions are omitted.

  The plurality of reading devices 4j are detected by the strain sensors or the vibration sensors from the corresponding wireless communication devices 2j via the corresponding wireless communication commands as the moving body 200 moves along the concrete block. Sensing information obtained by converting analog quantities into digital data is received. Thereby, the mobile body 200 provided with the plurality of reading devices 4j can collect the transition data of the concrete block. Data collected by the mobile unit 200 is transferred to a central control room (not shown) by communication means such as a telephone line or an internet line. Thereby, it becomes possible to always monitor the deterioration state.

  By adopting such a configuration, it is possible to collect the transition data of the concrete block of the bridge 10 only by passing the desired position without the moving body 200 reducing the speed, and therefore it is not necessary to run a special maintenance vehicle. That is, the maintenance management of the bridge 10 can be performed by installing a plurality of reading devices 4j on an ordinary business vehicle and running the same.

[Fifth Embodiment]
As the wireless communication device 2j, the passive UHF band RFID tag in the second embodiment may include a temperature sensor. For example, the wireless communication device 2j is a passive UHF band RFID tag with a built-in temperature sensor. Even in this configuration, for example, as described in the third embodiment, by analyzing the temperature data of the inner wall concrete, it is possible to detect the deterioration state of a specific portion of the inner wall concrete at an early stage.

[Sixth Embodiment]
As the wireless communication device 2j, the passive UHF band RFID tag in the second embodiment may include a strain sensor or a vibration sensor. For example, the wireless communication device 2j is a passive UHF band RFID tag incorporating a strain sensor or a vibration sensor. Also in this configuration, for example, as described in the fourth embodiment, maintenance management of the bridge 10 can be performed by installing a plurality of reading devices 4j on an ordinary business vehicle and running the same.

  As described above, according to the above embodiment, the mobile body 200 can collect sensing information of the wireless communication device 2j installed in the maintenance management target 300 at high speed without interfering with the adjacent wireless communication device 2j. It is. That is, the response signal from the wireless communication device 2j installed in the maintenance management target 300 can be read at a higher speed.

  Although the first to sixth embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design does not depart from the gist of the present invention. Etc. are also included. For example, the functions and configurations described in the first to sixth embodiments can be arbitrarily combined. In the above-described embodiment, the example in which the wireless communication device 2j is installed with the maintenance management target 300 as an example of the target object has been described. However, the target object is not limited to the target for maintenance management. It may be a subject.

  5 tunnel, 10 bridge, 12 bridge girder, 2j wireless communication device, 4j reading device, 100 wireless communication system, 200 mobile object, 300 maintenance target

Claims (5)

A wireless communication system comprising a wireless communication device capable of responding via a wireless communication command to sensing information obtained by converting an analog amount detected by a sensor into digital data, and a reading device for communicating with the wireless communication device. ,
The wireless communication device includes n types of wireless communication devices that respond to mutually different commands (n is a natural number),
The reader includes n types of readers capable of transmitting commands corresponding to the n types of wireless communication devices,
The n types of wireless communication devices, the first to n-th wireless communication devices are sequentially and repeatedly installed on the object at predetermined intervals,
In the n types of reading devices, first to n-th reading devices are sequentially and repeatedly installed at predetermined intervals on a movable body movable along the object.
Wireless communication system. Each of the n types of reading devices is installed on the mobile body with an interval equal to or greater than a reading range for the n types of wireless communication devices with a reading device installed next to the n types of reading devices.
The wireless communication system according to claim 1. The n kinds of reading devices receive the sensing information from the corresponding wireless communication devices via the corresponding commands as the moving body moves along the object.
The radio | wireless communications system of Claim 1 or Claim 2. The wireless communication device includes a temperature sensor as the sensor.
The radio | wireless communications system as described in any one of Claims 1-3. The wireless communication device includes a strain sensor or a vibration sensor as the sensor.
The radio | wireless communications system as described in any one of Claims 1-3.

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