Sensor terminal sheet and structure evaluation system

Abstract

To provide a sensor terminal sheet in which an increase in the amount of wiring due to an increase in the number of sensors can be suppressed and to provide a structure evaluation system.SOLUTION: A sensor terminal sheet is provided, having a plurality of sensor terminals and a wiring bus. Each of the plurality of sensor terminals has a sensor, a detection unit, and a communication unit. The sensor detects elastic waves. The detection unit extracts a feature quantity of the elastic waves based on the elastic waves detected by the sensor. The communication unit transmits via serial communication, the feature quantity of the elastic waves extracted by the detection unit. The wiring bus connects the plurality of sensor terminals. The plurality of sensor terminals are arranged at predetermined intervals on a sheet-like substrate, and have layered structure laminated with a film together with the wiring bus.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a sensor terminal sheet and a structure evaluation system. [Background technology]

[0002] In recent years, the deterioration of infrastructure structures has become a social issue, making traditional maintenance that relies on human labor difficult. As a countermeasure to this issue, structural health monitoring using AE (Acoustic Emission) sensors has attracted attention. AE is an ultrasonic elastic wave that occurs when an external force is applied to a material, causing deformation or destruction. By installing multiple AE sensors on a structure, the location of the AE source can be located based on the sensor's position information and the time difference between the AE reaching each sensor. This makes it possible to estimate the location of deformation or destruction inside the structure, enabling the diagnosis of the structure's health and efficient maintenance.

[0003] Conventionally used wired AE sensors have problems with installation and wiring management due to the need to install many sensors. Especially when monitoring high places and large structures, installing, removing and wiring AE sensors requires a lot of effort. This causes the maintenance costs to rise. One effective way to simplify sensor installation and removal is to integrate the sensor array with an adhesive sheet, but because the sensor output is analog, there is a problem that the number of wiring increases proportionally as the number of sensors increases. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] National Research and Development Agency, National Institute of Advanced Industrial Science and Technology, Dai Nippon Printing Co., Ltd., “Development of a sensor sheet that can monitor strain distribution in bridges”, [online], [Retrieved June 28, 2023], Internet<URL: https: / / www.dnp.co.jp / news / detail / 1187697_1587.html> [Non-Patent Document 2] Ken Kobayashi and 4 others, “Development of a bridge sensing system using flexible surface pattern sensors”, P.20-23, [online], [Retrieved June 28, 2023], Internet<URL: https: / / www.nedo.go.jp / content / 100888002.pdf > Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a sensor terminal sheet and a structure evaluation system that can suppress an increase in the number of wirings that accompanies an increase in the number of sensors. [Means for solving the problem]

[0006] The sensor terminal sheet of the embodiment has a plurality of sensor terminals and a wiring bus. The plurality of sensor terminals have a sensor, a detection unit, and a communication unit. The sensor detects elastic waves. The detection unit extracts a feature of the elastic wave based on the elastic wave detected by the sensor. The communication unit transmits the feature of the elastic wave extracted by the detection unit via serial communication. The wiring bus connects the plurality of sensor terminals. The plurality of sensor terminals are arranged at predetermined intervals on a sheet-like substrate, and have a layered structure laminated with a film together with the wiring bus. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing a system configuration of a sensor terminal sheet according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of a wiring bus according to the embodiment. [Diagram 3] FIG. 2 is a diagram showing an example of the configuration of a wiring bus according to the embodiment. [Figure 4] FIG. 2 is a diagram showing an example of the configuration of a sensor terminal according to the embodiment. [Diagram 5] FIG. 1 is a diagram showing an example of the configuration of a structure evaluation system according to an embodiment. [Figure 6] FIG. 1 is a diagram showing an example of the configuration of a structure evaluation device according to an embodiment. [Figure 7] FIG. 13 is a diagram showing an example of an arrangement of a sensor terminal sheet in a modified example. [Figure 8] FIG. 13 is a diagram showing an example of an arrangement of sensor terminals in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a sensor terminal sheet and a structure evaluation system according to an embodiment will be described with reference to the drawings.

[0009] FIG. 1 is a diagram showing a system configuration of a sensor terminal sheet 10 according to an embodiment. The sensor terminal sheet 10 is a sheet that can be adhered to a structure such as a bridge. In the following description, the structure is a bridge, but the structure does not have to be limited to a bridge. The structure may be any structure that generates elastic waves due to the occurrence or progression of a crack, or an external impact (e.g., rain, artificial rain, etc.). Note that bridges are not limited to structures erected over rivers, valleys, etc., but also include various structures (e.g., highway viaducts) that are set above the ground.

[0010] The sensor terminal sheet 10 is composed of a substrate 15, a plurality of sensor terminals 20-1 to 20-n (n is an integer of 2 or more), and a wiring bus 30. The substrate 15 is a flat, tape-like flexible substrate. Since the substrate 15 is flexible, the sensor terminal sheet 10 can be attached to a curved structure. The sensor terminal sheet 10 can be wound on a reel or the like, which has the advantage of being easy to transport and easy to mount on a mobile object such as a drone. The sensor terminals 20-1 to 20-n and the wiring bus 30 are arranged on the substrate 15. For example, the sensor terminals 20-1 to 20-n are arranged on the substrate 15 at a predetermined interval. The sensor terminal sheet 10 has a laminated structure in which the sensor terminals 20-1 to 20-n and the wiring bus 30 are laminated with a film.

[0011] The sensor terminal sheet 10 has a laminated structure including multiple layers such as a release film, an adhesive layer, a base layer, a conductive layer, an insulating layer, and a protective layer. The conductive layer may have multiple layers. The sensor terminal sheet 10 is attached to the structure by the adhesive layer. In order to efficiently propagate the elastic waves generated inside the structure to the sensor, it is desirable to adopt a material whose acoustic impedance of the adhesive layer and the base layer is consistent with the acoustic impedance of the structure. For example, an insulating material such as polyimide, PET, or Kapton may be used as the base film. The thickness of the entire sensor terminal sheet 10 is desirably several tens of um to several mm. The arrangement interval of the sensor terminals 20 on the sensor terminal sheet 10 is desirably several centimeters to 1 m. Since each sensor terminal 20 is connected to the wiring bus 30 in a daisy chain shape, the sensor terminal sheet 10 can be cut to a desired length as needed.

[0012] The sensor terminals 20-1 to 20-n have a detection function for detecting elastic waves generated inside the structure in which the sensor terminal sheet 10 is installed, and a communication function for transmitting information related to the detected elastic waves. The sensor terminals 20-1 to 20-n in the embodiment perform serial communication.

[0013] The wiring bus 30 is a bus for serial communication. Here, the configuration of the wiring bus 30 will be specifically described with reference to Figs. 2 and 3. Figs. 2 and 3 are diagrams showing an example of the configuration of the wiring bus 30 in the embodiment. Fig. 2 shows a configuration in which the wiring bus 30 has four wirings L1 to L4, and Fig. 3 shows a configuration in which the wiring bus 30 has five wirings L1 to L5. The wiring bus 30 shown in Fig. 2 is composed of four wirings, namely, a data signal SDA, a clock signal SCL, a ground GND, and a power supply Vcc. Adding a Vcc wiring makes it possible to incorporate a preamplifier in the sensor. The wiring bus 30 shown in Fig. 3 is composed of five wirings, namely, SDA, SCL, GND, Vcc, and a reference pulse signal REF.

[0014] 4 is a diagram showing an example of the configuration of the sensor terminal 20 in the embodiment. The sensor terminal 20 includes a sensor 21, a detection unit 22, and a communication unit .

[0015] The sensor 21 detects elastic waves generated from inside the structure on which the sensor terminal sheet 10 is installed. The sensor 21 is a piezoelectric MEMS (Micro Electro Mechanical Systems) sensor or a piezoelectric film type sensor. By using a thin sensor such as a piezoelectric MEMS sensor or a piezoelectric film type sensor as the sensor 21, it is possible to integrate the sensor, the sensor circuit, the protective film, and the adhesive sheet. Furthermore, by adopting a piezoelectric type sensor 21, it is not necessary to supply power to the sensor 21 during sensing, so that the sensor terminal 20 can be made more energy-efficient and simplified. By peeling off the release film and attaching the sensor terminal sheet 10 to the structure, the amount of work required to install the sensor terminal 20 can be significantly reduced. The sensor 21 converts the detected elastic waves into an electrical signal and outputs it.

[0016] The detection unit 22 extracts a feature amount of the elastic wave based on the elastic wave detected by the sensor 21. Furthermore, the detection unit 22 calculates the arrival time of the elastic wave at the sensor 21. The detection unit 22 is composed of an amplifier 221, a filter 222, an AD converter 223, and a signal processing unit 224.

[0017] The amplifier 221 amplifies the electrical signal output from the sensor 21. The amplifier 221 amplifies the electrical signal to a level that allows processing in, for example, an AD converter 223. The amplifier 221 outputs the amplified electrical signal to the filter 222.

[0018] The filter 222 removes noise components outside a predetermined band. The filter 222 is, for example, a band pass filter (BPF). The electrical signal from which noise has been removed by the filter 222 is input to the AD converter 223.

[0019] The AD converter 223 quantizes the electrical signal from which the noise has been removed and converts it into a digital signal. The AD converter 223 outputs the digital signal to the signal processing unit 224.

[0020] The signal processing unit 224 receives the digital signal output from the AD converter 223 as input. The signal processing unit 224 performs signal processing on the input digital signal. The signal processing performed by the signal processing unit 224 includes, for example, extraction of elastic wave feature values ​​and calculation of elastic wave arrival times. The signal processing unit 224 outputs information related to the elastic wave feature values ​​and elastic wave arrival times obtained by the signal processing to the communication unit 23. When outputting the information related to the elastic wave feature values ​​and elastic wave arrival times obtained by the signal processing, the signal processing unit 224 associates a sensor ID with the information. The sensor ID represents identification information for identifying the sensor terminal 20.

[0021] The signal processing unit 224 is configured using an analog circuit or a digital circuit. When the signal processing unit 224 is configured using an analog circuit, the AD converter 223 does not need to be provided between the sensor 21 and the signal processing unit 224. That is, when the signal processing unit 224 is configured using an analog circuit, an electric signal from which noise has been removed by the filter 222 is input to the signal processing unit 224. The digital circuit is realized by, for example, an FPGA (Field Programmable Gate Array) or a microcomputer. The digital circuit may be realized by a dedicated LSI (Large-Scale Integration). The signal processing unit 224 may be equipped with a non-volatile memory such as a flash memory or a removable memory. In the following description, a case where the signal processing unit 224 is configured using a digital circuit will be described.

[0022] The characteristic quantities of the elastic wave are, for example, the amplitude [mV] of the waveform, the rise time [usec] of the waveform, the duration [usec] of the gate signal, the number of zero cross counts [times], the energy [arb.] of the waveform, the frequency [Hz], and the root mean square (RMS) value. The amplitude of the waveform is, for example, the maximum amplitude value in the noise elimination signal. The rise time of the waveform is, for example, the time T1 from the start of the rise of the gate signal to the time when the noise elimination signal reaches its maximum value. The duration of the gate signal is, for example, the time from the start of the rise of the gate signal to the time when the amplitude becomes smaller than a preset value. The number of zero cross counts is, for example, the number of times the noise elimination signal crosses a reference line that passes through a zero value.

[0023] The energy of the waveform is, for example, a value obtained by integrating the squared amplitude of the noise-removing signal at each time point over time. The definition of the energy is not limited to the above example, and may be, for example, an approximation using the envelope of the waveform. The frequency is the frequency of the noise-removing signal. The RMS value is, for example, a value obtained by squaring the amplitude of the noise-removing signal at each time point and taking the square root.

[0024] The communication unit 23 performs serial communication with other sensor terminals 20 or external devices. The communication unit 23 transmits, for example, the feature amount of the elastic wave extracted by the detection unit 22 and information on the arrival time to the external device by serial communication. When the sensor terminal 20 is a master terminal, the communication unit 23 transmits information on the time obtained by the sensor terminal 20 itself to the other sensor terminals 20 via the wiring bus 30. When the sensor terminal 20 is a terminal other than the master terminal, the communication unit 23 receives information on the time transmitted from the sensor terminal 20 that is the master terminal via the wiring bus 30. The communication unit 23 employs an I2C (Inter-Integrated Circuit) method, which is a type of clock-synchronized serial communication. I2C is a communication method that transmits data one bit at a time in sequence using one signal line. The problem of an increase in the number of wirings due to an increase in the number of sensors is solved by digitally processing the output of the sensor 21 and converting it into serial communication. This makes it easy to reduce wiring and space in the entire device.

[0025] In order to pinpoint the location of the source of elastic waves with high accuracy based on the elastic waves detected by the sensors 21 provided in each sensor terminal 20, it is necessary to obtain the time difference of the elastic waves arriving at each sensor terminal 20 with high accuracy. By digitally processing the output of the sensor 21 and making it serial communication, it is possible to avoid an increase in the number of lines, but this makes it difficult to achieve time synchronization, which is necessary for positioning. There are two possible methods for time synchronization. The first method is a method in which an external relay device transmits a reference signal including information about time to each sensor terminal 20 to perform time synchronization. The second method is a method in which the sensor terminals 20 other than the master terminal perform time synchronization based on the output signal of the sensor terminal 20 that is the master terminal among the multiple sensor terminals 20 provided in the sensor terminal sheet 10.

[0026] The first method can be realized when the wiring bus 30 has four wires as shown in Fig. 2. In the first method, an external relay device transmits a reference signal including information about time to each sensor terminal 20, and each sensor terminal 20 can use the reference signal to determine the arrival time difference of the elastic waves at each sensor terminal 20. However, since the source of the elastic waves and the timing of their generation are unknown, the relay device needs to keep sending the reference signal at regular time intervals. This may result in a high load on the entire system.

[0027] The second method can be realized when the wiring bus 30 has five wires as shown in Fig. 3. In the second method, one sensor terminal 20 (e.g., sensor terminal 20-1) is arbitrarily selected from the multiple sensor terminals 20 and set as the master terminal. The elastic wave (e.g., the amplitude of the digitized elastic wave) detected by the sensor terminal 20-1 is transmitted as information related to time information to the sensor terminals 20 other than the master terminal via the reference pulse signal REF of the wiring bus 30.

[0028] The signal processor 224 of the sensor terminals 20 other than the master terminal calculates the arrival time of the elastic wave at each sensor terminal 20 based on the time difference between the rising time of the hit gate of the elastic wave, which indicates the arrival timing of the detected elastic wave, and information on the time information (reference pulse signal). The time difference can be measured by counting the rising edge interval of two gate signals with the number of clocks. As another time difference measurement method, a TDC (Time-To-Digital Converter) that measures the time difference between two gate signals with high accuracy based on the propagation delay of the logic gate may be used. The TDC is a method that takes the logical sum of a start pulse and a stop pulse that have passed through multiple stages of logic gates, and measures the time difference by the product of the number of delay gates whose output has changed and the delay time per gate. The delay time per gate is, for example, on the order of about 10 ps, ​​and high-accuracy time difference measurement is possible.

[0029] According to the sensor terminal sheet 10 configured as above, it is possible to suppress an increase in the number of wirings accompanying an increase in the number of sensors. Specifically, the sensor terminal sheet 10 includes a plurality of sensor terminals 20 and a wiring bus 30. The plurality of sensor terminals 20 include a sensor 21, a detection unit 22, and a communication unit 23. The sensor 21 detects an elastic wave. The detection unit 22 extracts a feature of the elastic wave based on the elastic wave detected by the sensor 21. The communication unit 23 transmits the feature of the elastic wave extracted by the detection unit 22 by serial communication. The wiring bus 31 connects the plurality of sensor terminals 20. The plurality of sensor terminals 20 are arranged at a predetermined interval on the sheet-shaped substrate 15, and have a laminated structure laminated with a film together with the wiring bus 30. In this way, in the sensor terminal sheet 10, the output of the sensor terminal 20 is digitally processed and communicated by serial communication. This makes it possible to suppress an increase in the number of wirings accompanying an increase in the number of sensors. Furthermore, the number of wirings in the entire device can be reduced, and the scale of the sensor terminal sheet 10 can be reduced.

[0030] Furthermore, the sensor terminal sheet 10 can facilitate sensor installation by integrating a plurality of sensor terminals 20 with an adhesive sheet.

[0031] (System using the sensor terminal sheet 10) Next, a structure evaluation system 100 using the above-mentioned sensor terminal sheet 10 will be described. Fig. 5 is a diagram showing an example of the configuration of the structure evaluation system 100 in an embodiment. The structure evaluation system 100 is used to evaluate the soundness of a structure. In the following description, evaluation means determining the degree of soundness of a structure, that is, the deterioration state of a structure, based on a certain criterion.

[0032] Damage that affects the evaluation of the deterioration state of a structure includes damage inside the structure that impedes the propagation of elastic waves 11, such as cracks, cavities, and sedimentation. Here, cracks include vertical cracks, horizontal cracks, and diagonal cracks. A vertical crack is a crack that occurs in a direction perpendicular to the road surface. A horizontal crack is a crack that occurs in a direction horizontal to the road surface. A diagonal crack is a crack that occurs in a direction other than horizontal and vertical to the road surface. Sedimentation is a deterioration in which concrete turns into sediment, mainly at the boundary between the asphalt and the concrete deck.

[0033] The structure evaluation system 100 includes a plurality of sensor terminal sheets 10-1 to 10-m (m is an integer equal to or greater than 2), a plurality of relay devices 60-1 to 60-m, and a structure evaluation device 70. The plurality of sensor terminal sheets 10-1 to 10-m and the plurality of relay devices 60-1 to 60-m are connected via connectors 50-1 to 50-m. The plurality of relay devices 60-1 to 60-m and the structure evaluation device 70 are connected wirelessly.

[0034] Each of the sensor terminals 20-1-1 to 20-1-n is linked to the relay device 60-1 via the wiring bus 30-1. Each of the sensor terminals 20-m-1 to 20-mn is linked to the relay device 60-m via the wiring bus 30-m. Each of the sensor terminals 20-1-1 to 20-1-n, 20-m-1 to 20-mn transmits transmission data including the feature amount of the elastic wave (at least the amplitude of the elastic wave) extracted in and information regarding the arrival time of the elastic wave to the relay devices 60-1 to 60-m by I2C communication.

[0035] The relay devices 60-1 to 60-m transfer the transmission data obtained from each of the sensor terminals 20-1-1 to 20-1-n, 20-m-1 to 20-mn to the structure evaluation device 70 by wireless communication. It is preferable that the relay devices 60-1 to 60-m include at least a first communication unit, a second communication unit, and a memory. The first communication unit performs I2C communication with each of the sensor terminals 20. The second communication unit performs wireless communication with the structure evaluation device 70. The memory temporarily stores the transmission data.

[0036] The structure evaluation device 70 analyzes the transmission data collected from the relay devices 60-1 to 60-m, and estimates the deterioration state and the deterioration location of the structure. This enables the diagnosis of the soundness of the structure and efficient maintenance and management. An address is assigned to each sensor terminal 20, and transmission and reception are performed between the sensor terminal 20 specified by the master. This allows the usage interval of the sensor terminal to be adjusted to an integer multiple of the sensor arrangement interval. The sensor terminals 20 to which no address is assigned can also be used as spare sensor terminals.

[0037] 6 is a diagram showing an example of the configuration of a structure evaluation device 70 in an embodiment. The structure evaluation device 70 includes a communication unit 71, a control unit 72, a storage unit 73, and a display unit 74. The communication unit 71 receives one or more pieces of transmission data transferred from each relay device 60.

[0038] The control unit 72 controls the entire structure evaluation device 70. The control unit 72 is configured using a processor such as a CPU (Central Processing Unit) and a memory. The control unit 72 executes a program to function as an acquisition unit 721, an event extraction unit 722, a position determination unit 723, a distribution generation unit 724, and an evaluation unit 725.

[0039] Some or all of the functional units of the acquisition unit 721, the event extraction unit 722, the positioning unit 723, the distribution generation unit 724, and the evaluation unit 725 may be realized by hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA, or may be realized by cooperation between software and hardware. The program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a non-transitory storage medium such as a portable medium such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), or a CD-ROM, or a storage device such as a hard disk built into a computer system. The program may be transmitted via an electric communication line.

[0040] Some of the functions of the acquisition unit 721, the event extraction unit 722, the position determination unit 723, the distribution generation unit 724, and the evaluation unit 725 do not need to be pre-installed in the structure evaluation device 70, and may be realized by installing additional application programs in the structure evaluation device 70.

[0041] The acquisition unit 721 acquires various information. For example, the acquisition unit 721 acquires transmission data received by the communication unit 71. The acquisition unit 721 acquires transmission data for an evaluation target period. The acquisition unit 721 stores the acquired transmission data in the storage unit 73.

[0042] The event extraction unit 722 extracts transmission data for one event from the transmission data for the evaluation period stored in the memory unit 73. An event refers to an elastic wave generating event that occurs in a structure. In this embodiment, the elastic wave generating event is the passage of a vehicle over a road surface. When one event occurs, elastic waves are detected at approximately the same time by multiple sensors 21. In other words, the memory unit 73 stores transmission data related to elastic waves detected at approximately the same time. Therefore, the event extraction unit 722 sets a predetermined time window and extracts all transmission data whose arrival time is within the range of the time window as transmission data for one event. The event extraction unit 722 outputs the extracted transmission data for one event to the position location unit 723.

[0043] The time window range Tw may be determined using the elastic wave propagation velocity v in the target structure and the maximum sensor interval dmax so as to be in the range of Tw≧dmax / v. In order to avoid erroneous detection, it is desirable to set Tw to a value as small as possible, so that Tw=dmax / v can be practically satisfied. The elastic wave propagation velocity v may be obtained in advance.

[0044] The position locating unit 723 locates the position of the elastic wave source based on the sensor position information and the sensor ID and time information included in each of the multiple pieces of transmission data extracted by the event extracting unit 722.

[0045] The sensor position information includes information on the installation position of the sensor terminal 20 in association with the sensor ID. The sensor position information includes information on the installation position of the sensor terminal 20, such as latitude and longitude, or horizontal and vertical distances from a reference position of the structure. The positioning unit 723 holds the sensor position information in advance. The sensor position information may be stored in the positioning unit 723 at any timing before the positioning unit 723 performs positioning of the elastic wave source.

[0046] The sensor position information may be stored in the storage unit 73. In this case, the position locating unit 723 acquires the sensor position information from the storage unit 73 at the timing of performing position locating. A Kalman filter, a least squares method, or the like may be used to locate the position of the elastic wave source. The position locating unit 723 outputs the position information of the elastic wave source obtained during the evaluation period to the distribution generating unit 724.

[0047] The distribution generating unit 724 receives as input the position information of the multiple elastic wave sources output from the position determining unit 723. The distribution generating unit 724 generates an elastic wave source distribution using the input position information of the multiple elastic wave sources. The elastic wave source distribution represents a distribution in which the positions of the elastic wave sources are indicated. More specifically, the elastic wave source distribution is a distribution in which the horizontal axis represents the distance in the traffic direction and the vertical axis represents the distance in the width direction, and in which points indicating the positions of the elastic wave sources are indicated on virtual data representing the structure to be evaluated.

[0048] The distribution generating unit 724 generates an elastic wave source density distribution using the elastic wave source distribution. The elastic wave source density distribution represents a distribution in which a density value calculated according to the number of elastic wave sources included in each region is indicated for each region determined in advance in the elastic wave source distribution. Specifically, the distribution generating unit 724 first divides the elastic wave source distribution into a plurality of regions by dividing the elastic wave source distribution into predetermined sections. Next, the distribution generating unit 724 calculates the density of each region by dividing the number of elastic wave sources located in the region by the area of ​​the region. Then, the distribution generating unit 724 generates an elastic wave source density distribution by allocating the calculated density value of each region to each region. In this way, the distribution generating unit 724 generates an elastic wave source density distribution by calculating the density for the evaluation target region.

[0049] The evaluation unit 725 evaluates the deterioration state of the structure in which the sensor terminal sheet 10 is installed, using the elastic wave source density distribution generated by the distribution generation unit 724. For example, the evaluation unit 725 evaluates an area in the elastic wave source density distribution where the density of the elastic wave source is equal to or greater than a threshold as a healthy area, and evaluates an area where the density of the elastic wave source is less than the threshold as a damaged area.

[0050] The storage unit 73 stores the transmission data for the evaluation period acquired by the acquisition unit 721. The storage unit 43 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device.

[0051] The display unit 74 displays the evaluation results under the control of the evaluation unit 725. For example, the display unit 74 may display the corrected elastic wave source density distribution as the evaluation result, or may display the area considered to be a damaged area in a different display mode from other areas. The display unit 74 is an image display device such as a liquid crystal display or an organic EL (Electro Luminescence) display. The display unit 74 may be an interface for connecting the image display device to the structure evaluation device 70. In this case, the display unit 74 generates a video signal for displaying the evaluation result and outputs the video signal to the image display device connected to itself.

[0052] (Variation 1) In the above-described embodiment, the multiple sensor terminals 20 provided on the sensor terminal sheet 10 are arranged in a row, but there is no particular limitation on the arrangement of the multiple sensor terminals 20 provided on the sensor terminal sheet 10. For example, the multiple sensor terminals 20 provided on the sensor terminal sheet 10 may be arranged in a radial, annular or polygonal shape.

[0053] (Variation 2) In the above-described embodiment, the sensor terminal sheets 10 are arranged one-dimensionally, but the sensor terminal sheets 10 may be arranged two-dimensionally. FIG. 7 is a diagram showing an example of an arrangement of the sensor terminal sheets 10 in a modified example. In the example shown in FIG. 7, a plurality of sensor terminal sheets 10-1 to 10-m are connected to one relay device 60 by a wiring cable 75. With such a configuration, it is possible to reduce the number of relay devices 60. Although not shown in FIG. 7, the arrangement of the sensor terminal sheets 10-1 to 10-m is not limited to the arrangement in FIG. 7, and they may be arranged in a radial, annular or polygonal shape.

[0054] (Variation 3) In the above-described embodiment, the sensor terminals 20 are arranged in one dimension, but the sensor terminals 20 may be arranged in two dimensions. FIG. 8 is a diagram showing an example of an arrangement of the sensor terminals 20 in a modified example. In the example shown in FIG. 8, a set of a plurality of sensor terminals 20 is arranged in parallel on the substrate 15 included in one sensor terminal sheet 10. This configuration makes it easier to arrange the sensor terminals 20, and also makes it possible to reduce the number of relay devices 60. Although not shown in FIG. 8, the arrangement of the sensor terminals 20 included in the sensor terminal sheet 10 is not limited to the arrangement in FIG. 8, and the sensor terminals 20 may be arranged in a radial, annular, or polygonal shape.

[0055] (Variation 4) In the above-described embodiment, the resonant frequencies of the sensors 21 included in each of the multiple sensor terminals 20 may be the same, or at least some of the sensors 21 may have different resonant frequencies.

[0056] The following supplementary notes are provided regarding the sensor terminal sheet 10 shown in this embodiment. (Additional Note) The following notes are disclosed: A sensor (e.g., sensor 21) for detecting elastic waves; A detection unit (e.g., detection unit 22) that extracts a feature amount of the elastic wave based on the elastic wave detected by the sensor; A communication unit (e.g., a communication unit 23) that transmits the feature amount of the elastic wave extracted by the detection unit by serial communication; A sensor terminal (for example, the sensor terminal 20) comprising:

[0057] According to at least one embodiment described above, the sensor terminal sheet 10 has a plurality of sensor terminals 20 and a wiring bus 30. The plurality of sensor terminals 20 have a sensor 21, a detection unit 22, and a communication unit 23. The sensor 21 detects elastic waves. The detection unit 22 extracts a feature of the elastic wave based on the elastic wave detected by the sensor 21. The communication unit 23 transmits the feature of the elastic wave extracted by the detection unit 22 by serial communication. The wiring bus 31 connects the plurality of sensor terminals 20. The plurality of sensor terminals 20 are arranged at predetermined intervals on the sheet-like substrate 15, and have a laminated structure laminated with a film together with the wiring bus 30, thereby making it possible to suppress an increase in the number of wirings accompanying an increase in the number of sensors.

[0058] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0059] 10, 10-1 to 10-m... sensor terminal sheet, 15... substrate, 20, 20-1 to 20-n, 20-1-1 to 20-1-n, 20-m-1 to 20-mn... sensor terminal, 21... sensor, 22... detection unit, 23... communication unit, 30, 30-1 to 30-m... wiring bus, 50, 50-1 to 50-m... connector, 60, 60-1 to 60-m... relay device, 70... structure evaluation device, 221... amplifier, 222... filter, 223... AD converter, 224... signal processing unit

Claims

1. A sensor for detecting elastic waves; A detection unit that extracts a feature amount of the elastic wave based on the elastic wave detected by the sensor; a communication unit that transmits the feature amount of the elastic wave extracted by the detection unit through serial communication; A plurality of sensor terminals each having a wiring bus connecting the plurality of sensor terminals; Equipped with The sensor terminal sheet has a laminated structure in which the plurality of sensor terminals are arranged at predetermined intervals on a sheet-like substrate and laminated together with the wiring bus with a film.

2. any one of the plurality of sensor terminals is designated as a master terminal, and a detection unit of the sensor terminal designated as the master terminal determines an arrival time of the elastic wave, and outputs a reference pulse signal including information of the determined arrival time of the elastic wave to sensor terminals other than the master terminal via the wiring bus. The sensor terminal sheet according to claim 1 .

3. The detection unit included in the sensor terminal other than the master terminal further Calculating the arrival time of the elastic wave based on a time difference between a rise time indicating the arrival timing of the elastic wave detected by the device itself and a time indicated by information on the arrival time of the elastic wave included in the reference pulse signal. The sensor terminal sheet according to claim 2 .

4. The communication unit included in each of the plurality of sensor terminals transmits the feature amount of the elastic wave extracted by the detection unit and information related to the arrival time of the elastic wave to an external device via a relay device. The sensor terminal sheet according to claim 3 .

5. The laminated structure is composed of a release film, an adhesive layer, a base layer, a conductive layer, an insulating layer and a protective layer, and the conductive layer is composed of one or more layers. The sensor terminal sheet according to claim 1 or 2.

6. The acoustic impedance of the adhesive layer and the base layer is matched to the acoustic impedance of a structure in which the plurality of sensor terminals are installed. The sensor terminal sheet according to claim 5 .

7. the plurality of sensor terminals are arranged on the sheet-like substrate in one or two dimensions; The sensor terminal sheet according to claim 1 or 2.

8. The sensor included in each of the plurality of sensor terminals is a piezoelectric type Micro Electro Mechanical Systems (MEMS) sensor or a piezoelectric type film type sensor. The sensor terminal sheet according to claim 1 or 2.

9. Some of the sensors included in each of the plurality of sensor terminals have different resonant frequencies, The sensor terminal sheet according to claim 1 or 2.

10. The sensor terminal sheet according to claim 1 or 2; one or more relay devices that receive transmission data including at least a feature amount of the elastic wave obtained by the sensor terminal sheet from the sensor terminal sheet via the serial communication and transfer the received transmission data; a structure evaluation device that evaluates a deterioration state of a structure in which the sensor terminal sheet is installed based on the transmission data transferred from the one or more relay devices; and A structure evaluation system comprising:

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