JP2011209244A - Water level measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem wherein when water level is detected using a method utilizing a conventional image processing method and a sensor detecting difference of electric resistance, complicated processing and complicated constitution are required and atime is spent on these processing, resulting in delayed announcement of an alert in an emergency.SOLUTION: Communication is always performed using an RFID system and dangerous water level is detected based on whether communication is completed in signal strength above a certain signal level, resulting in the water level measuring system where water level is measured and detected quickly and inexpensively with a simplified processing.

Description

  The present invention relates to a water level measurement system using wireless communication.

  As a method for measuring the water level, there is a sensor system that measures the water level by installing a sensor element on a measurement target such as a river or a tank and detecting water (liquid) by the sensor element. For example, it is a method of measuring the water level by detecting a change in electrical resistance by increasing the electrical resistance when the sensor element is immersed in water.

  As another method, there is an image-type water level observation system that measures a water level by imaging a water level measurement location such as a river or a tank and processing the captured image. For example, the detection is performed based on whether or not a water level measurement marker previously set in the captured image is hidden by water (see, for example, Patent Document 1).

JP 2001-307274 A

  However, in the method of measuring the water level with a sensor, a detection unit that detects a change in electrical resistance must be installed at the site to be measured.

  In addition, in an image processing apparatus, it takes time for complicated image processing, and when an emergency is required, the issuing of an alarm may be delayed.

  The present invention has been made in view of the above circumstances, and always performs communication using an RFID system, and detects the dangerous water level based on whether or not communication can be performed with a signal strength of a certain level or more, thereby enabling simple processing. An object of the present invention is to provide a water level measurement system capable of measuring and detecting a water level quickly and inexpensively.

In order to achieve the above object, the water level measurement system of the present invention comprises:
When a transmission command for transmitting a radio signal is detected at a predetermined height of a measurement target, a tag that transmits the radio signal;
Reading means for transmitting the transmission command to the tag at regular intervals and receiving the radio signal from the tag;
A water level measuring means for detecting that the water level has reached the predetermined height when the radio signal from the tag cannot be received within the predetermined time after the transmission of the transmission command;
It is characterized by providing.

  According to the present invention, it is possible to provide a quick and inexpensive water level measurement system without requiring complicated processing.

The figure which shows the structure of the water level measurement system before the flooding in the 1st Embodiment of this invention. The conceptual diagram of the water level measurement system in the case of trying to communicate with respect to a tag from the reading part after the flooding in the 1st Embodiment of this invention. The conceptual diagram of the water level measurement system in the case of trying to communicate with respect to a reading part from a tag in the 1st Embodiment of this invention after submergence. The figure which illustrates the signal strength of the signal sent from the tag which the reading part after the submergence received in the 1st Embodiment of this invention received. The flowchart which shows the operation | movement of the 1st Embodiment of this invention. The figure which shows the structure of the water level measurement system before the flooding in the 2nd Embodiment of this invention. The figure which shows the structure of the water level measurement system after the flooding in the 2nd Embodiment of this invention. The figure which illustrates the signal strength of the signal sent from the tag which the reading part after the flooding in the 2nd Embodiment of this invention received. The flowchart which shows the operation | movement of the 2nd Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram showing a configuration of a water level measurement system before submergence in the first embodiment of the present invention.

  FIG. 2 is a conceptual diagram of the water level measurement system in the first embodiment of the present invention when communication is performed from the reading unit to the tag after flooding.

  FIG. 3 is a conceptual diagram of a water level measurement system in the first embodiment of the present invention when communication is performed from a tag to a reading unit after submergence.

  As shown in FIG. 1, the water level measurement system of the present embodiment includes an IC tag 10, a reading unit 21, a control unit 22, a display unit 23, a broadcasting unit 24, and a communication unit 25.

The control unit 32, the display unit 33, the broadcast unit 34, and the communication unit 35 are included.

  The IC tag 10 is installed at a place where the water level is measured. For example, the IC tag 10 is installed on a boundary line (hereinafter referred to as a flooding point) of a bridge strut over a river whether or not it is a critical water level. The IC tag 10 stores the identification information in the semiconductor integrated circuit chip, detects the signal when receiving a signal return instruction of a certain strength or higher from the reading unit 21, and stores the stored identification information as a radio signal. To the reading unit 21. In the present embodiment, not the identification information but a response signal including no information may be used.

  “Constant intensity” is a reception intensity necessary for the IC tag 10 to transmit a signal. The radio wave intensity of the radio signal during communication in the gas phase 1b shown in FIG. 1 and the IC intensity as shown in FIG. This is a so-called threshold value between the strengths of radio signals when communication is impossible, such as when the tag 10 is completely submerged in water (when the IC tag 10 is in the liquid phase 1a whose water level is lower than the water surface 1ab). The accuracy can be increased by lowering the threshold, and the accuracy can be adjusted lower by increasing the threshold.

  The signal response instruction radio wave from the reading unit 21 is attenuated due to factors such as separation into a reflected wave and a transmitted wave. For example, it is assumed that the radio wave intensity of wireless communication in the gas phase 1b is 100 dB and the radio wave intensity of wireless communication in the liquid phase 1a is 10 dB. At this time, the threshold value is set to, for example, 50 dB between 10 to 99 dB. In this case, even if a signal return instruction of 30 dB or less is received, the IC tag 10 does not return a signal (wireless signal). The IC tag 10 does not transmit a radio signal when the reception intensity does not exceed the threshold. The attenuation factor is not only because it is separated into a reflected wave and a transmitted wave, but there are many other factors such as energy transfer (absorption) to water, water flow, and dirt. Therefore, when wireless communication is performed at a frequency of 2.45 GHz, for example, a frequency at which so-called electromagnetic waves are easily absorbed by water, if the water surface exists within a straight line connecting the reading unit 21 and the IC tag 10, these wireless communication is The reception strength is unlikely to exceed the threshold.

  Here, as shown in FIG. 3, it is assumed that a signal return instruction having a certain strength or higher is received even when the IC tag 10 is under the surface of the water. Even in this case, transmission of a signal (wireless signal) from the IC tag 10 is attenuated by being separated into a reflected wave and a transmitted wave on the water surface 1ab, and the wireless signal intensity received by the reading unit 21 is attenuated. . That is, a factor that hinders communication twice is generated by exchanging signals once. Even in such a case, the reading unit 21 cannot receive the radio wave from the IC tag 10, and the water level can be detected with higher accuracy.

  Further, since the semiconductor integrated circuit chip of the passive type IC tag receives power from a radio signal, it does not require a power source, and is excellent in maintainability in this respect. In this embodiment, since it is immersed in water at the time of flooding, it is still more suitable if waterproof coating is made. Some passive type IC tags use frequencies such as 135 KHz, 13, 56 MHz, 433 MHz, 900 MHz band, 2.45 GHz, and the like. It is preferable to use a 2.45 GHz passive type IC tag.

  The reading unit 21 transmits a signal return instruction with a certain strength as a wireless signal to the IC tag 10 via the antenna. For example, various antennas such as a horn antenna, an array antenna, and a dipole antenna can be used as the antenna. Further, a highly accurate communication method using a DSRC (Dedicated Short Range Communication) method may be used. The reading unit 21 sends a signal return instruction to the IC tag 10 at regular intervals, and reads a signal sent from the IC tag 10. The fixed interval can be set as appropriate, and is, for example, every few seconds to several tens of seconds.

The control unit 22 detects the radio wave intensity of the radio signal received by the reading unit 21 and determines whether the radio wave intensity is equal to or higher than a threshold value, or a reply from the IC tag 10 within a predetermined time after transmitting a signal reply instruction. It is determined whether or not. If it is determined that the radio wave intensity is equal to or less than the threshold value or that no reception is made, the display unit 22 and the broadcast unit 23 are notified that the water level has exceeded the flood point. For example, as shown in FIG. 4, the reception intensity of up flood time t _k of the radio signal of the reading portion 21 is beyond the threshold value, after the time t _k is the received intensity falls below the threshold. In this case, detects the radio wave strength falls below the threshold value after submergence time t _k, it is determined that the water level has exceeded the installed height of the IC tag 10. When the installation height is the submergence point, the display unit 22 and the broadcast unit 23 are notified to issue alarm information. In other words, the reception intensity equal to or higher than the threshold and the reception intensity lower than the threshold are replaced with whether or not reception is possible, and binarization processing is performed.

  Moreover, you may notify a remote place via the wireless communication part 25 whether the water level exceeded the flooding point.

  The display unit 23 is a screen that displays character information and video information such as a liquid crystal screen. When the information that the water level has exceeded the flooding point is not notified from the control unit 22, nothing may be displayed, or a sentence or the like indicating that the water level is normal may be displayed. When a notification that the water level has exceeded the flooding point is received from the control unit 22, for example, a letter that calls attention to the surroundings in red, such as “Please evacuate because the critical water level has been exceeded in the river” Post.

  The broadcast unit 24 is a device that urges the alarm to the surroundings by sound from a speaker or the like. If the information that the water level has exceeded the flooding point is not notified from the control unit 22, nothing may be emitted, or some music or the like may flow. When receiving a notification from the control unit 22 that the water level has exceeded the flooding point, for example, "~~ Please evacuate because the water level has been exceeded in the river" or a siren to warn Etc.

  The communication unit 25 is an antenna system that performs wireless communication, for example. Inform the system that displays and alerts away from the place where the water level is measured that the water level has exceeded the flood point. In addition, you may notify that a water level is normal. In the present embodiment, it is represented wirelessly, but instead of the antenna system, it may be replaced with a wired system that notifies within a reachable range.

  The control unit 32 causes the display unit 33 and the broadcast unit 34 to post or issue alarm information on the information received by the communication unit 35. The control unit 22 may receive the radio wave intensity information as it is, and may determine whether to cause the display unit 33 or the broadcast unit 34 to issue an alarm based on another standard.

  The display unit 33 is a display screen having the same function as the display unit 23. Used to display danger information.

  The broadcasting unit 34 is a sound generating device such as a speaker having the same function as the broadcasting unit 24. It is used to inform the surroundings of danger information through sound.

  Next, the operation of the first embodiment will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating the signal intensity of a signal transmitted from a tag received by a reading unit before and after submergence in the first embodiment of the present invention.

  FIG. 5 is a flowchart showing the operation of the first exemplary embodiment of the present invention.

  First, a signal reply instruction that is a transmission command for transmitting a wireless signal from the reading unit 21 to the IC tag 10 is transmitted. The signal reply instruction is transmitted at regular intervals, for example, every 10 seconds (step S101).

  Within 10 seconds from this signal reply instruction, the reading unit 21 reads the reply of the wireless signal from the IC tag 10. The control unit 22 determines whether or not the radio field intensity of the transmitted radio signal is greater than or equal to a threshold value or is returned (step S102).

If the control unit 22 determines that the radio wave intensity of the radio signal from the IC tag 10 cannot be received within the threshold value or within a certain time (for example, 10 seconds) (NO in step S102), the water level is flooded to the display unit 23. The display unit 23 and the broadcast unit 24 are notified that the points have been exceeded. The notified display unit 23 urges the surroundings to be alerted by posting or broadcasting characters such as “Please evacuate because the dangerous water level has been exceeded in the river”. For example, as shown in FIG. 4, the reception intensity of up flood time t _k of the radio signal of the reading portion 21 is beyond the threshold value, after the time t _k is the received intensity falls below the threshold. In this case, the signal detection threshold following reception strength after submergence time t _k is made, the display unit 22, so that the water level to the broadcast unit 23 is notified that exceeds the flood point IC tag 10 is installed . Moreover, you may notify a remote place via the wireless communication part 25 whether the water level exceeded the flooding point (step S103).

  Thereafter, a new signal return instruction is issued from the reading unit 21 to the IC tag 10 (step S101).

  In step 102, if the received radio wave intensity detected by the control unit 22 is determined to be higher than the threshold value, the alarm information is not notified to the display unit 23 and the broadcast unit 24. If warning information is displayed or broadcast, the display or broadcast may be terminated (step S104).

  Thereafter, a new signal return instruction is issued from the reading unit 21 to the IC tag 10 (step S101).

  As described above, by using this embodiment, it is possible to provide a quick and inexpensive water level measurement system without requiring complicated processing. That is, the IC tag 10 and the reading unit 21 can easily and quickly issue a warning by determining whether or not the inundation point has been exceeded depending on whether or not the radio wave intensity of a certain intensity can be received, that is, whether or not communication is possible. This is a system that issues an alarm.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS.

  The difference between the present embodiment and the first embodiment is that a plurality of IC tags 10 are provided.

  Differences in components from the first embodiment will be described.

The IC tags 10a and 10b are tags each having identification information. The IC tags 10a and 10b store the identification information in the semiconductor integrated circuit chip, detect the signal when receiving a signal return instruction of a certain intensity or more from the reading unit 21, and wirelessly store the stored identification information. It transmits to the reading part 21 via a signal.
In addition, the control unit 22 receives the identification information and notifies the display unit 23 and the broadcast unit 24 of the received radio wave identification information.

  At this time, for example, it is assumed that the installation position (installation height) of the IC tag 10a is a warning water level, and the installation position (installation height) of the IC tag 10b is a warning water level that should be alerted around. Therefore, as shown in FIG. 8, if the reading unit 21 receives a signal received from the IC tag 10 a below the threshold or fails to receive the signal, the display unit 23 and the broadcasting unit 24 display a signal for displaying or broadcasting attention information for calling attention. To notify. If the received radio wave of the signal from the IC tag 10b is less than the threshold value or cannot be received, the display unit 23 and the broadcast unit 24 are notified of a signal to display or broadcast an alarm.

  The display unit 23 displays the water level information corresponding to each IC tag 10a, 10b sent from the control unit 22, and when receiving a signal for displaying a caution or an alarm, displays the urgent alarm around the display. For example, if the IC tag 10b is a warning water level that should alert the surroundings, when the water level reaches the IC tag 10a, the water level information corresponding to the installation height of the IC tag 10a is displayed. Further, when the water level reaches the IC tag 10b, the water level information corresponding to the installation height of the IC tag 10b is displayed, and the text etc. for warning are also displayed.

  The alarm unit 24 broadcasts water level information corresponding to the installation height of each IC tag 10a, 10b sent from the control unit 22. If it is not dangerous, the current water level information may not be broadcast, and the water level information may be provided as a safe indication or just as information provision.

  Next, the operation of the second embodiment will be described with reference to FIG.

  FIG. 9 is a flowchart showing the operation of the second exemplary embodiment of the present invention.

  First, a signal return instruction which is a transmission command for transmitting a radio signal from the reading unit 21 to the IC tags 10a and 10b is transmitted. The signal reply instruction is transmitted at regular intervals, for example, every 10 seconds (step S201).

  Until the next signal reply instruction is transmitted, that is, within 10 seconds from the previous signal reply instruction, the reading unit 21 determines whether or not there is a wireless signal reply from the IC tag 10a. Specifically, the reading unit 21 transmits a wireless signal returned from the IC tag 10 a to the control unit 22. The control unit 22 determines whether or not the radio field intensity of the transmitted radio signal is equal to or greater than a threshold value (step S202).

  If the radio wave intensity of the radio signal from the IC tag 10a is detected at a threshold value or more within a certain time (for example, 10 seconds), the alarm information is not notified to the display unit 23 and the broadcast unit 24. If attention information or warning information is displayed or broadcast, the display or broadcast may be terminated (step S204).

  Thereafter, a new signal reply instruction is issued from the reading unit 21 to the IC tag 10 (step S201).

  In the present embodiment, if the radio field intensity of the radio signal from the IC tag 10a cannot be observed at a value equal to or higher than the threshold value within a certain time (for example, 10 seconds), the radio signal returned from the IC tag 10b is next sent. It is determined whether or not the signal can be observed (step S203).

  Here, when the wireless signal cannot be observed, the control unit 22 can detect that the water level is not less than the installation height of the IC tag 10a and not more than the installation height of the IC tag 10b. In this case, a response when the IC tag 10a is flooded is displayed. For example, if the installation position of the IC tag 1a is a caution water level that calls attention to the surroundings, the fact is notified to the display unit 23 or the broadcast unit 24 to display or broadcast the caution information (step S205).

  Next, a case where a reception signal equal to or higher than the threshold value cannot be obtained from the IC tag 10b in step S203 will be described.

  In this case, a countermeasure is taken when the IC tag 10b is submerged. For example, assuming that the installation position of the IC tag b is a warning water level for calling attention to the surroundings, the fact is notified to the display unit 23 or the broadcast unit 25, and the warning information is displayed or broadcast (step S206).

  Thereafter, a new signal reply instruction is issued from the reading unit 21 to the IC tag 10 (step S201).

  As described above, according to the present embodiment, more accurate water level measurement can be performed by using the plurality of IC tags 10a and 10b. In addition, by issuing warnings to the surroundings in stages, water level information before and after reaching the warning water level can be transmitted to the surroundings. Furthermore, since wireless signals are exchanged in a question format, the wireless signal path can have two obstruction factors and can be used for more accurate water level detection.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. For example, the number of IC tags can be 3 or more. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, you may delete the component of the control part 32, the display part 33, the broadcast part 34, and the communication part 35 from all the structural elements shown by embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1a ... Gas phase 1b ... Liquid phase 1ab ... Water surface (boundary surface)
DESCRIPTION OF SYMBOLS 10 ... IC tag 10a ... IC tag 10b ... IC tag 10c ... IC tag 21 ... Reading part 22 ... Control part 23 ... Display part 24 ... Broadcasting part 25 ... Communication part 32 ... Control part 33 ... Display part 34 ... Broadcasting part 35 ... Communication department

Claims (6)

When a transmission command for transmitting a radio signal is detected at a predetermined height of a measurement target, a tag that transmits the radio signal;
Reading means for transmitting the transmission command to the tag at regular intervals and receiving the radio signal from the tag;
A water level measuring means for detecting that the water level has reached the predetermined height when the radio signal from the tag cannot be received within the predetermined time after the transmission of the transmission command;
A water level measurement system comprising: A tag that is installed at a predetermined height of the measurement target and detects a transmission command for transmitting a wireless signal, and transmits the wireless signal with a constant signal strength;
Reading means for transmitting the transmission command to the tag at regular intervals and receiving the radio signal;
A determination unit that determines whether or not the reading unit has received the wireless signal whose reception intensity exceeds a threshold value within the predetermined time;
When the determination unit determines that the reception intensity of the wireless signal is below a threshold, it detects that the water level has reached the predetermined height,
A water level measuring means for detecting that the water level has not reached the predetermined height when the determination unit has a radio signal reception intensity exceeding a threshold;
A water level measurement system comprising: The first tag that transmits the first identification information when the transmission command that transmits the identification information that identifies the self and the other is installed is installed at the first height of the measurement target;
When installed at a position higher than the first height and detecting the transmission command, a second tag that transmits second identification information;
Reading means for transmitting the transmission command to the first tag and the second tag every predetermined time, and receiving the transmitted first identification information and second identification information;
After transmitting the transmission command and within the predetermined time,
If the first identification information cannot be received and the second identification information can be received, it is detected that the water level has reached the first height,
If the second identification information could not be received, water level measuring means for detecting that the water level has reached the second height,
A water level measurement system comprising: When the water level detected by the water level measuring means reaches a dangerous water level, an alarm means for displaying or broadcasting an alarm for alerting the surroundings;
The water level measurement system according to claim 1, further comprising: The water level measurement system according to claim 1, wherein the frequency of the radio signal is 900 MHz. The water level measurement system according to claim 1, wherein the frequency of the radio signal is 2.45 GHz.

Images