Detection device

Abstract

This detection device comprises: a plurality of sensors that measure vibrations in the ground; a position information acquisition unit that acquires position information of the plurality of sensors; an instruction unit that instructs the plurality of sensors to start measurement; and a measurement unit that acquires a measurement signal, which is the measurement result from the plurality of sensors, that synchronizes measurement timings of the plurality of sensors on the basis of an instruction from the instruction unit, and that, on the basis of the measurement signal after synchronization and the position information acquired by the position information acquisition unit, determines the position of damage to a pipe-shaped structure embedded in the ground.

Description

Detection device

[0001] The present invention relates to a detection device for detecting damage to structures such as pipes buried in the ground.

[0002] Patent Document 1 describes that a Geophone (hereinafter referred to as a geophone), which is a velocity sensor using a coil and a magnet, is widely used as a sensor for detecting damage to structures such as pipes buried in the ground.

[0003] International Publication No. 2019-082292

[0004] In vibration sensors using sound such as geophones, noise generated by normal environments, such as automobiles or human walking, may intrude. Also, since the state of the underground soil is not always the same, the time of the signal transmitted to the geophone is not always the same as the ideal state where there are no obstacles on the ground. Therefore, detecting only based on the speed of the signal transmitted to the geophone may not be able to accurately determine the location of the damage due to the influence of the soil and noise.

[0005] An object of the present invention is to provide a detection device that can accurately and precisely determine the location of damage without being affected by soil or noise.

[0006] The detection device of this invention includes a plurality of sensors for measuring vibrations in the ground, a position information acquisition unit for acquiring the position information of the plurality of sensors, an instruction unit for instructing the plurality of sensors to start measurement, a measurement signal that is the measurement result of the plurality of sensors is acquired, and based on the instruction of the instruction unit, the measurement timings of the plurality of sensors are synchronized, and based on the synchronized measurement signal and the position information acquired by the position information acquisition unit, a measurement unit for determining the damage location of the pipe-shaped structure buried in the ground.

[0007] According to this invention, it is possible to provide a detection device that can accurately and precisely determine the location of damage to a pipe-shaped structure installed in the ground without being affected by soil or noise.

[0008] This is a schematic diagram of a detection device 1 according to an embodiment of the present invention. This is a block diagram showing the configuration of the sensor 10A. This is a block diagram showing the configuration of the information processing terminal 20. This is a flowchart showing the operation of the detection device 1. This is a block diagram showing the functional configuration of the detection device 1.

[0009] Figure 1 is a schematic diagram showing the configuration of the detection device 1 of this embodiment. The detection device 1 shown in Figure 1 has a plurality of sensors 10A, 10B, and 10C (three in this embodiment) and an information processing terminal 20. The detection device 1 of this embodiment uses the three sensors 10A, 10B, and 10C to determine the location of damage to a pipe-shaped structure buried underground. In particular, in this embodiment, the location of damage to a water pipe is determined as the pipe-shaped structure buried underground, and the location of water leakage is determined.

[0010] Multiple sensors 10A, 10B, and 10C are installed on the ground surface. However, multiple sensors 10A, 10B, and 10C may be buried underground. In this embodiment, two of the three sensors 10B and 10C are installed directly above a location where it is estimated that a water pipe is buried (for example, near a fire hydrant), and the remaining sensor 10A is installed between the two sensors 10A and 10B. However, the locations in which the multiple sensors are installed in the present invention are not limited to the example in Figure 1.

[0011] Figure 2 is a block diagram showing the configuration of sensor 10A. Since sensors 10A, 10B, and 10C all have the same configuration and function, Figure 2 shows the configuration of sensor 10A as a representative example. Sensor 10A includes a CPU 11, RAM 12, flash memory 13, geophone 14, UWB (Ultra Wide Band) communication unit 15, and BLE (Bluetooth® Low Energy) communication unit 16.

[0012] The CPU 11 reads the operation program stored in the flash memory 13 into the RAM 12 and controls the sensor 10A.

[0013] Geophone 14 is an example of an acoustic sensor. Geophone 14 consists of a magnet and a coil and outputs a measurement signal in response to vibrations in the ground. The frequency range that geophone can detect is 0.01 Hz to 100 kHz.

[0014] The UWB communication unit 15 is a wireless communication function that utilizes an ultra-wideband frequency bandwidth (for example, a bandwidth of several hundred MHz to several GHz). The UWB communication unit 15 communicates wirelessly with the UWB communication units 15 of other sensors according to the control of the CPU 11.

[0015] BLE16 communicates with the information processing terminal 20 via short-range wireless communication. However, communication with the information processing terminal 20 is not limited to the BLE standard; it may also use other standards such as Wi-Fi®, RFID (Radio Frequency Identification), NFC (Near-field Communication), or wired communication such as USB.

[0016] The information processing terminal 20 consists of a personal computer or a smartphone, etc. Figure 3 is a block diagram showing the configuration of the information processing terminal 20. The information processing terminal 20 includes a display 21, a user interface 22, a CPU 23, RAM 24, a communication unit 25, and flash memory 26.

[0017] The CPU 23 reads the program stored in the flash memory 26, which is the storage medium, into the RAM 24 and controls the information processing terminal 20. The display 21 displays the GUI (Graphical User Interface) related to the program. The user interface 22 is, for example, a touch panel stacked on the display 21, and accepts user operations via the GUI.

[0018] The communication unit 25 is a communication unit conforming to wireless communication standards such as UWB, Wi-Fi (registered trademark), RFID, NFC, LTE (Long Term Evolution), or 5G (fifth generation mobile communication system). In this embodiment, the communication unit 25 performs short-range wireless communication with the sensor 10 in accordance with the BLE standard.

[0019] Figure 4 is a flowchart showing the operation of the detection device 1. Figure 5 is a block diagram showing the functional configuration of the detection device 1. Functionally, the information processing terminal 20 comprises an instruction unit 200, a location information acquisition unit 201, and a measurement unit 202.

[0020] The instruction unit 200 of the information processing terminal 20 transmits a measurement start trigger to the representative sensor via the communication unit 25 (S11). The representative sensor may be specified by the user using a GUI, or the nearest sensor (with the highest radio wave strength) may be automatically selected. Alternatively, the information processing terminal 20 may designate a sensor connected via a wired connection such as USB as the representative sensor. In this embodiment, as an example, sensor 10A is designated as the representative sensor.

[0021] Upon receiving the measurement start trigger, sensor 10A transmits a start message corresponding to the measurement start trigger to the other sensors 10B and 10C via the UWB communication unit 15 (S12). Sensors 10A, 10B, and 10C each measure the distance between them and acquire the measurement signal from the geophone 14 using the functions of the UWB communication unit 15 (S13).

[0022] Sensors 10A, 10B, and 10C determine the relative distance between them using methods such as ToF (Time of Flight), SDS-TWR (Symmetrical Double-Sided Two-Way Range), TDoA (Time Difference of Arrival), or IPD (Internal Phase Difference).

[0023] For example, in Time of Flight (ToF), sensor 10A sends the above start message at a certain time t0. At this time, sensor 10A starts measuring the geophone 14. The measurement is performed for a predetermined time (for example, 10 to 30 seconds).

[0024] Upon receiving the start message, sensor 10B records the time t1 at which the start message was received. At this time, sensor 10B begins measuring the geophone 14. When sensor 10B finishes measuring the geophone 14, it sends a response message to sensor 10A at the time t2 at which the measurement is completed. Sensor 10B includes the information of the time t1 at which the start message was received and the time t2 at which the response message is sent in the response message. In other words, the time t1 at which the start message was received by sensor 10B becomes the start time of the geophone 14 measurement. The measurement time for sensor 10B is the same as for sensor 10A, and is performed for a predetermined time, for example (e.g., 10 to 30 seconds).

[0025] Sensor 10A, upon receiving a response message, records the reception time t3 of the response message. Sensor 10A calculates the average transmission and reception time difference between sensors 10A and 10B from the time difference between time t0 and time t1, and the time difference between time t2 and time t3.

[0026] In a similar manner, sensor 10A determines the average transmission and reception time difference of electromagnetic waves between sensor 10A and sensor 10C. In this case as well, for sensor 10C, the time t1 at which the start message is received becomes the start time of measurement for the geophone 14.

[0027] In SDS-TWR, for example, sensor 10A sends the above start message at a certain time t0. Sensor 10B, upon receiving the start message, records the time t1 when the start message was received and sends a response message back at time t2. Upon receiving the response message, sensor 10A further sends a completion message to sensor 10B. At this time, sensor 10A, upon receiving the response message, includes the time t0 when the start message was sent, the time t3 when the response message was received, and the time t4 when the completion message was sent, and sends them to sensor 10B.

[0028] In SDS-TWR, errors due to the processing time of each sensor can be canceled out by transmitting and receiving electromagnetic waves multiple times. Therefore, even if the clocks of sensors 10A, 10B, and 10C are not perfectly synchronized, the accurate transmission and reception time difference can be determined.

[0029] The transmission and reception time differences of electromagnetic waves between sensors 10A, 10B, and 10C, as determined above, can be converted into relative distances. Once the relative distances between sensors 10A, 10B, and 10C are determined, their relative positions are also determined.

[0030] Sensors 10A, 10B, and 10C each transmit a measurement signal related to the measurement result of the geophone 14 in their response message (or completion message). In this case, sensor 10A, which is the representative sensor, receives the measurement signal related to the measurement result of the geophone 14.

[0031] Sensor 10A transmits the measurement signals from sensors 10A, 10B, and 10C, as well as information relating to the transmission and reception time difference of electromagnetic waves between sensors 10A, 10B, and 10C, to the information processing terminal 20 (S14).

[0032] The information processing terminal 20 determines the water leak location based on the measurement signals and transmission / reception time difference information received from sensor 10A. More specifically, the measurement unit 202 of the information processing terminal 20 acquires measurement signals, which are the measurement results of multiple sensors, and synchronizes the measurement signals of multiple sensors based on the instructions of the instruction unit 200. Synchronization is performed based on the transmission / reception time difference of electromagnetic waves between sensors 10A, 10B, and 10C measured by UWB. For example, the time t0 when sensor 10A sends a start message becomes the measurement start time of the geophone 14, and the measurement start time at sensor 10B is the time t2 when the start message is received. The information processing terminal 20 synchronizes the measurement start time at sensor 10B with the measurement start time at sensor 10A using the transmission / reception time difference of electromagnetic waves between sensor 10A and sensor 10B. Similarly, the information processing terminal 20 synchronizes the measurement start time at sensor 10C with the measurement start time at sensor 10A using the transmission / reception time difference of electromagnetic waves between sensor 10A and sensor 10C.

[0033] Furthermore, the information processing terminal 20 obtains the position information of sensors 10A, 10B, and 10C from information relating to the transmission and reception time difference of the received electromagnetic waves. As described above, the information processing terminal 20 converts the transmission and reception time difference of electromagnetic waves between sensors 10A, 10B, and 10C into a relative distance and obtains the relative positions between sensors 10A, 10B, and 10C.

[0034] The information processing terminal 20 then determines the location of damage to a pipe-shaped structure (e.g., a water pipe) buried underground based on the measurement signals from the geophones 10A, 10B, and 10C. When a pipe-shaped structure such as a water pipe is damaged, fluid such as water leaks out from the damaged location. At the damaged location, a characteristic sound is produced by the leaked fluid. This sound is detected as vibration by the geophones 14. The information processing terminal 20 determines the location of the water leak estimated by each sensor by comparing the measurement signals from each sensor with a reference waveform such as a water leak, for example, by pattern matching. Alternatively, the information processing terminal 20 may prepare a machine learning model that has learned the relationship between the measurement signals and the water leak location using a predetermined learning algorithm, and determine the water leak location by inputting the measurement signals into the machine learning model.

[0035] The information processing terminal 20 then considers the overlapping position of the three sensors 10A, 10B, and 10C (for example, the weighted center of gravity position) as the final water leakage location.

[0036] As described above, the detection device 1 of this embodiment can accurately and precisely determine the location of a water leak with high precision, even when a single sensor cannot accurately determine the location of the water leak due to the influence of soil or noise, by using the measurement results of multiple sensors and the principle of triangulation using the positional information of multiple sensors.

[0037] In the above embodiment, an example was shown in which the information processing terminal 20 functionally includes a location information acquisition unit 201 that acquires location information from multiple sensors and a measurement unit 202 that determines the location of a water leak. However, the location information acquisition unit 201 and the measurement unit 202 may be provided by a representative sensor (for example, sensor 10A). In this case, sensor 10A transmits information indicating the determined water leak location to the information processing terminal 20. Alternatively, sensor 10A may be equipped with a display and display information indicating the water leak location on the display.

[0038] In the above embodiment, a water pipe was shown as the pipe-shaped structure buried underground. However, the pipe-shaped structure buried underground could be, for example, a gas pipe, and is not limited to a water pipe.

[0039] In the above embodiment, an example was shown in which the relative position information of each sensor is determined based on the information of the time difference in the transmission and reception of electromagnetic waves by UWB. However, the method of determining the position information of each sensor is not limited to the above example. For example, if each sensor is equipped with GPS (Global Positioning System) functionality, the position information obtained by GPS may be considered as the position information of each sensor. Furthermore, the relative position information may be determined not only based on the time difference in the transmission and reception of electromagnetic waves, but also based on RSSI (Received Signal Strength Indicator) information or phase difference.

[0040] In the case of UWB, due to the positional accuracy of UWB, the relative distance between sensors 10A, 10B, and 10C should preferably be within 20m. In the case of GPS, the absolute position must be determined with an error of at least 30cm. The measurement unit 202 utilizes the amplitude, resonance point, and phase of the vibration itself, and the position information acquisition unit 201 acquires the relative or absolute distance and position between the measurement units 202, and processes the data based on the interrelationship of these relative positions and the vibration information.

[0041] In addition, in the above embodiment, an example of synchronizing the measurement signals of each sensor based on the information on the transmission / reception time difference of electromagnetic waves by UWB was shown, but the synchronization method is not limited to the above example. For example, it is also possible for each sensor to synchronize using the time information included in the GPS signal by GPS. However, by acquiring relative position information and synchronizing the measurement signals based on the information on the transmission / reception time difference of electromagnetic waves by UWB as in this embodiment, there is no need to separately provide other configurations or functions for synchronization.

[0042] Note that the number of sensors may be even more, or may be two. When the number of sensors is two, if they are installed directly above the position where it is estimated that the water pipe is buried (for example, near a fire hydrant), it can be estimated that there is a leakage position between the two sensors.

[0043] In this embodiment, a geophone was used to estimate the damage position of the underground pipe-shaped structure. However, for example, other vibration meters such as an accelerometer or a hydrophone may be used to estimate the damage position.

[0044] The description of this embodiment is illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

[0045] 1: Detection device 10A: Sensor 10B: Sensor 10C: Sensor 11: CPU 12: RAM 13: Flash memory 14: Geophone 15: UWB communication unit 16: Communication unit 20: Information processing terminal 21: Display 22: User I / F 23: CPU 24: RAM 25: Communication unit 26: Flash memory 200: Instruction unit 201: Position information acquisition unit 202: Measurement unit

Claims

1. A detection device comprising: a plurality of sensors for measuring vibrations in the ground; a position information acquisition unit for acquiring position information of the plurality of sensors; an instruction unit for instructing the plurality of sensors to start measurement; and a measurement unit that acquires measurement signals which are the measurement results of the plurality of sensors, synchronizes the measurement timing of the plurality of sensors based on the instruction of the instruction unit, and determines the location of damage to a pipe-shaped structure buried in the ground based on the synchronized measurement signals and the position information acquired by the position information acquisition unit.

2. The detection device according to claim 1, wherein the position information acquisition unit obtains the position information by determining the relative distance between the plurality of sensors.

3. The detection device according to claim 2, wherein each of the plurality of sensors is equipped with a wireless communication unit, and the position information acquisition unit determines the relative distance between the plurality of sensors based on the electromagnetic waves transmitted and received by the wireless communication unit.

4. The detection device according to claim 3, wherein the synchronization is performed based on the time difference between the transmission and reception of electromagnetic waves between the plurality of sensors.

5. The detection device according to any one of claims 1 to 4, wherein each of the plurality of sensors includes an acoustic sensor.

6. The detection device according to any one of claims 1 to 5, wherein the number of the plurality of sensors is three or more.

7. The detection device according to any one of claims 1 to 6, wherein the plurality of sensors are installed on the ground surface.

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