Sensor terminal sheet and structural 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 methods that rely on human labor difficult. Structural health monitoring using acoustic emission (AE) sensors has attracted attention as a solution to this problem. AE is an elastic wave in the ultrasonic range that occurs when an external force is applied to a material, causing deformation or damage. By installing multiple AE sensors on a structure, the location of the AE source can be determined based on the sensor's position information and the time difference between the AE waves arriving at each sensor. This makes it possible to estimate the location of deformation or damage inside the structure, enabling health diagnosis and efficient maintenance of the structure.

[0003] Conventionally used wired AE sensors have had difficulties in installation and wiring management due to the need to install a large number of sensors. Particularly when monitoring high places or large structures, installing, removing, and wiring AE sensors requires a great deal of effort. This causes 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 in 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 capable of monitoring 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 four others, "Development of a bridge sensing system using flexible surface pattern sensors", pp. 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 each have a sensor, a detection unit, and a communication unit. The sensor detects elastic waves. The detection unit extracts features of the elastic waves based on the elastic waves detected by the sensor. The communication unit transmits the features of the elastic waves 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 in which the sensor terminals and the wiring bus are laminated with a film. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a system configuration of a sensor terminal sheet according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a wiring bus according to the embodiment. [Figure 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. [Figure 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. 10 is a diagram showing an example of the arrangement of a sensor terminal sheet in a modified example. [Figure 8] FIG. 10 is a diagram showing an example of an arrangement of sensor terminals in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[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 the 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 cracks or external impacts (for example, rain, artificial rain, etc.). Note that bridges are not limited to structures built over rivers or valleys, but also include various structures built above ground level (for example, highway viaducts).

[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 greater), and a wiring bus 30. The substrate 15 is a flat, tape-like flexible substrate. Because the substrate 15 is flexible, the sensor terminal sheet 10 can be attached to curved structures. The sensor terminal sheet 10 can be wound up on a reel or the like, which has the advantage of being easy to transport and 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 predetermined intervals. The sensor terminal sheet 10 has a layered 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 with multiple layers, including a release film, an adhesive layer, a base layer, a conductive layer, an insulating layer, and a protective layer. The conductive layer may also have multiple layers. The sensor terminal sheet 10 is attached to a structure using an adhesive layer. To efficiently transmit elastic waves generated inside the structure to the sensors, it is desirable to use materials whose acoustic impedances for the adhesive layer and base layer match the acoustic impedance of the structure. For example, insulating materials such as polyimide, PET, and Kapton may be used for the base film. The overall thickness of the sensor terminal sheet 10 is desirably several tens of microns to several millimeters. The sensor terminals 20 on the sensor terminal sheet 10 are desirably spaced apart at intervals of several centimeters to 1 meter. Because each sensor terminal 20 is connected to the wiring bus 30 in a daisy chain configuration, the sensor terminal sheet 10 can be cut to any 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 this 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 an embodiment. FIG. 2 shows a configuration in which the wiring bus 30 has four wires L1 to L4, and FIG. 3 shows a configuration in which the wiring bus 30 has five wires L1 to L5. The wiring bus 30 shown in FIG. 2 is composed of four wires: a data signal SDA, a clock signal SCL, a ground GND, and a power supply Vcc. Adding a Vcc wire makes it possible to incorporate a preamplifier into the sensor. The wiring bus 30 shown in FIG. 3 is composed of five wires: 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 according to 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. Using a thin sensor such as a piezoelectric MEMS sensor or a piezoelectric film-type sensor as the sensor 21 makes it possible to integrate the sensor, sensor circuit, protective film, and adhesive sheet. Furthermore, by adopting a piezoelectric type sensor 21, a power supply to the sensor 21 is not required during sensing, thereby achieving power saving and simplification of the sensor terminal 20. 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 it to be processed 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 noise-removed electrical signal and converts it into a digital signal, which is then output 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, extracting elastic wave feature quantities and calculating the arrival times of the elastic waves. The signal processing unit 224 outputs information relating to the elastic wave feature quantities and the arrival times of the elastic waves obtained by the signal processing to the communication unit 23. When outputting the information relating to the elastic wave feature quantities and the arrival times of the elastic waves 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 electrical 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 also 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 explanation, a case where the signal processing unit 224 is configured using a digital circuit will be described.

[0022] The elastic wave feature quantities include, for example, the waveform amplitude [mV], the waveform rise time [usec], the duration of the gating signal [usec], the number of zero-cross counts [times], the waveform energy [arb.], the frequency [Hz], and the root mean square (RMS) value. The waveform amplitude is, for example, the maximum amplitude value of the noise-removed signal. The waveform rise time is, for example, the time T1 from the start of the rising edge of the gating signal until the noise-removed signal reaches its maximum value. The duration of the gating signal is, for example, the time from the start of the rising edge of the gating signal until the amplitude becomes smaller than a predetermined value. The number of zero-cross counts is, for example, the number of times the noise-removed signal crosses a reference line passing through a zero value.

[0023] The waveform energy is, for example, the value obtained by integrating the squared amplitude of the noise-removed signal at each time point over time. Note that the definition of energy is not limited to the above example, and may be approximated using, for example, the envelope of the waveform. The frequency is the frequency of the noise-removed signal. The RMS value is, for example, the value obtained by squaring the amplitude of the noise-removed 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. For example, the communication unit 23 transmits elastic wave feature values ​​extracted by the detection unit 22 and information related to the arrival time to an external device via serial communication. When the sensor terminal 20 is a master terminal, the communication unit 23 transmits information related to the time acquired by the sensor terminal 20 itself to other sensor terminals 20 via the wiring bus 30. When the sensor terminal 20 is not a master terminal, the communication unit 23 receives information related to the time transmitted from the sensor terminal 20 that is the master terminal via the wiring bus 30. The communication unit 23 employs the I2C (Inter-Integrated Circuit) method, a type of clock-synchronized serial communication. I2C is a communication method that transmits data one bit at a time sequentially using a single signal line. Digitally processing the output of the sensor 21 for serial communication solves the problem of increased wiring due to an increase in the number of sensors. This easily reduces wiring and space required for 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 calculate the time difference between the elastic waves arriving at each sensor terminal 20 with high accuracy. Digitally processing the output of the sensor 21 for serial communication can avoid an increase in the number of lines, but this makes time synchronization necessary for positioning more difficult. There are two possible methods for time synchronization. The first method is a method in which an external relay device transmits a reference signal containing information about time to each sensor terminal 20 to perform time synchronization. The second method is a method in which sensor terminals 20 other than the master terminal perform time synchronization based on the output signal of the sensor terminal 20 that serves as the master terminal among the multiple sensor terminals 20 provided on 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 containing information about time to each sensor terminal 20, and each sensor terminal 20 uses the reference signal to determine the arrival time difference of the elastic waves at each sensor terminal 20. However, because the source of the elastic waves and the timing of their generation are unknown, the relay device must continue to send the reference signal at regular time intervals. This may increase the 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 (for example, sensor terminal 20-1) is arbitrarily selected from the multiple sensor terminals 20 and set as the master terminal. The elastic waves (for example, the amplitude of the digitized elastic waves) detected by the sensor terminal 20-1 are 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 processing unit 224 of each sensor terminal 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 edge of the elastic wave hit gate, which indicates the arrival timing of the detected elastic wave, and information related to the time information (reference pulse signal). The time difference can be measured by counting the interval between the rising edges of two gate signals using the number of clocks. Another time difference measurement method may be a time-to-digital converter (TDC), which measures the time difference between two gate signals with high precision based on the propagation delay of logic gates. The TDC calculates the time difference by taking the logical sum of the start pulse and stop pulse that have passed through multiple logic gates, and calculating 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 10 ps, ​​enabling high-precision time difference measurement.

[0029] The sensor terminal sheet 10 configured as described above can suppress an increase in the number of wirings required due to an increase in the number of sensors. Specifically, the sensor terminal sheet 10 includes multiple sensor terminals 20 and a wiring bus 30. The multiple sensor terminals 20 each include a sensor 21, a detection unit 22, and a communication unit 23. The sensor 21 detects elastic waves. The detection unit 22 extracts elastic wave features based on the elastic waves detected by the sensor 21. The communication unit 23 transmits the elastic wave features extracted by the detection unit 22 via serial communication. The wiring bus 31 connects the multiple sensor terminals 20 together. The multiple sensor terminals 20 are arranged at predetermined intervals on a sheet-like substrate 15 and have a laminated structure in which the sensor terminals 20 and the wiring bus 30 are laminated with a film. In this way, the sensor terminal sheet 10 digitally processes the output of the sensor terminals 20 and transmits it via serial communication. This suppresses an increase in the number of wirings required due to an increase in the number of sensors. Furthermore, the number of wires in the entire device can be reduced, allowing for a smaller sensor terminal sheet 10.

[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 sensor terminal sheet 10) Next, a structure evaluation system 100 using the above-described 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, i.e., the state of deterioration of a structure, based on a certain standard.

[0032] Damage that affects the evaluation of the deterioration state of a structure includes damage inside the structure that obstructs the propagation of elastic waves 11, such as cracks, cavities, and sedimentation. Here, cracks include vertical cracks, horizontal cracks, and diagonal cracks. Vertical cracks are cracks that occur in a direction perpendicular to the road surface. Horizontal cracks are cracks that occur horizontally to the road surface. Diagonal cracks are cracks that occur in a direction other than horizontal or vertical to the road surface. Sedimentation is 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 of 2 or more), 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 a relay device 60-1 via a wiring bus 30-1. Each of the sensor terminals 20-m-1 to 20-mn is linked to a relay device 60-m via a wiring bus 30-m. Each of the sensor terminals 20-1-1 to 20-1-n and 20-m-1 to 20-mn transmits transmission data including the extracted elastic wave feature amount (at least the elastic wave amplitude) and information related to the elastic wave arrival time to the relay devices 60-1 to 60-m via 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 via wireless communication. The relay devices 60-1 to 60-m preferably 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 state and location of deterioration of the structure. This enables the diagnosis of the health 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 designated by the master. This makes it possible to adjust the interval between sensor terminals in use to an integer multiple of the sensor placement interval. Sensor terminals 20 that are not assigned an address 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 according to 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, event extraction unit 722, position determination unit 723, distribution generation unit 724, and 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 a combination of software and hardware. The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, read-only memories (ROMs), and CD-ROMs, and non-transitory storage media such as hard disks built into computer systems. The program may be transmitted via a telecommunications 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 types of information. For example, the acquisition unit 721 acquires transmission data received by the communication unit 71. The acquisition unit 721 acquires transmission data for the evaluation 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 a vehicle passing over the 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 falls 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 determination 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 spacing dmax so that it is in the range of Tw≧dmax / v. To avoid false detection, it is desirable to set Tw to as small a value as possible, so that Tw can essentially be set to dmax / v. The elastic wave propagation velocity v may be determined 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 plurality of transmission data extracted by the event extracting unit 722.

[0045] The sensor position information includes information about the installation position of the sensor terminal 20 in association with the sensor ID. The sensor position information includes information about 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 generation unit 724 receives as input the position information of the multiple elastic wave sources output from the position determination unit 723. The distribution generation 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 indicating the positions of the elastic wave sources. More specifically, the elastic wave source distribution is a distribution in which points indicating the positions of the elastic wave sources are displayed on virtual data representing the structure to be evaluated, with the horizontal axis representing the distance in the traffic direction and the vertical axis representing the distance in the width direction.

[0048] The distribution generation 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 density values ​​calculated according to the number of elastic wave sources included in each predetermined region in the elastic wave source distribution are indicated. Specifically, the distribution generation unit 724 first divides the elastic wave source distribution into multiple regions by dividing it into predetermined sections. Next, the distribution generation unit 724 calculates the density of each region by dividing the number of elastic wave sources located within the region by the area of ​​the region. Then, the distribution generation unit 724 generates an elastic wave source density distribution by assigning the calculated density value for each region to each region. In this way, the distribution generation unit 724 generates an elastic wave source density distribution by calculating the density for the region to be evaluated.

[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 sources is equal to or greater than a threshold as a healthy area, and evaluates an area where the density of the elastic wave sources 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 73 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 results and outputs the video signal to the image display device connected to the display unit 74.

[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 are no particular limitations 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, multiple sensor terminal sheets 10-1 to 10-m are connected to one relay device 60 by a distribution cable 75. This configuration makes it 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 shown in FIG. 7, and they may be arranged in a radial, circular, or polygonal shape.

[0054] (Variation 3) In the above-described embodiment, the sensor terminals 20 are arranged one-dimensionally, but the sensor terminals 20 may be arranged two-dimensionally. 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 multiple sensor terminals 20 is arranged in parallel on the substrate 15 provided on 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 provided on the sensor terminal sheet 10 is not limited to the arrangement shown in FIG. 8, and the sensor terminals 20 may be arranged in a radial, circular, or polygonal shape.

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

[0056] The following notes are provided regarding the sensor terminal sheet 10 shown in this embodiment. (Addendum) 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., communication unit 23) that transmits the feature amount of the elastic wave extracted by the detection unit via 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 each have a sensor 21, a detection unit 22, and a communication unit 23. The sensor 21 detects elastic waves. The detection unit 22 extracts features of the elastic waves based on the elastic waves detected by the sensor 21. The communication unit 23 transmits the features of the elastic waves extracted by the detection unit 22 via serial communication. The wiring bus 31 connects the plurality of sensor terminals 20 together. The plurality of sensor terminals 20 are arranged at predetermined intervals on a sheet-like substrate 15, and have a laminated structure in which the sensor terminals 20 and the wiring bus 30 are laminated with a film, thereby suppressing an increase in the number of wires that accompanies an increase in the number of sensors.

[0058] Although several 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 within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [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 via serial communication; a plurality of sensor terminals each including 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 are 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 on the determined arrival time of the elastic wave to the 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 the 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 one-dimensionally or two-dimensionally on the sheet-like substrate; 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 MEMS (Micro Electro Mechanical Systems) sensor or a piezoelectric 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 the feature quantity 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 the 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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