State determination device, method, program, and recording medium

Abstract

To cope with the difference of eddy currents due to the depth of a reinforcement 2a in a reinforcement concrete 2 when the state of the reinforcement 2a is determined according to the eddy currents EC generated by exciting the reinforcement 2a inside the reinforcement concrete 2.SOLUTION: A state determination device 1 includes an excitation unit 1a configured to excite a reinforcing bar 2a inside a ferroconcrete 2, a plurality of magnetic measuring units 1b configured to measure magnetic fields generated by eddy currents EC generated in the reinforcing bar 2a, a correspondence recording unit 1d configured to record a correspondence between a state of the reinforcing bar 2a and a measured result of the magnetic measuring units 1b, and a state determination unit 1d configured to determine the state of the reinforcing bar 1b based on the measured result of the magnetic measuring units and a recorded content of the correspondence recording unit. 2a 1e. The recorded contents of the correspondence relation recording part 1d are for the case where the reinforcement 2a is disposed at a plurality of depths in the reinforcement concrete 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to determining the state (for example, presence or absence of corrosion) of a measurement target (for example, reinforcing steel) inside an object (for example, reinforced concrete). [Background technology]

[0002] Various methods have been proposed for non-destructively inspecting the corrosion of rebars in reinforced concrete. Currently, electrochemical methods such as half-cell potential and polarization resistance are the mainstream. Other methods that have been proposed include electromagnetic radar, ultrasound, and excitation heating. However, these methods are highly dependent on the measurement environment (changes in the relative dielectric constant due to humidity and water content) and the condition inside the concrete (presence or absence of cracks and cavities), and the problem is that they only provide low-accuracy results.

[0003] On the other hand, measurements using a magnetic field can measure the effects of only the reinforcing bars without being affected by the measurement environment and the conditions inside the concrete. Methods for detecting reinforcing bar corrosion using a magnetic field are described in Patent Documents 1 to 7.

[0004] Patent Documents 1 to 4 describe methods that do not utilize the generation of eddy currents by an excitation coil. These methods have various problems. For example, they cannot be considered completely non-destructive testing because they must pass a current through the rebars (Patent Document 1), the magnetization state of each rebar varies (Patent Document 2), a strong magnetic field must be generated to magnetize the rebars (Patent Document 3), it is unclear whether corrosion of rebars located deep in reinforced concrete can be detected, and measurement results vary greatly depending on the surrounding environment (Patent Document 4).

[0005] Patent Documents 5 to 7 describe methods that utilize the generation of eddy currents by an excitation coil. However, in Patent Documents 5 to 7, a single detection coil is used to detect the eddy currents. Note that Patent Documents 8 to 12 also describe methods that utilize the generation of eddy currents in the object to detect the state of the object. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-138094 [Patent Document 2] Japanese Patent Publication No. 2020-12851 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-292572 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-194341 [Patent Document 5] Japanese Patent Application Publication No. 2019-15655 [Patent Document 6] Japanese Patent Application Publication No. 2018-25434 [Patent Document 7] Japanese Patent Application Publication No. 2019-128161 [Patent Document 8] Japanese Patent Application Laid-Open No. 2016-105046 [Patent Document 9] Japanese Patent Application Laid-Open No. 2016-114533 [Patent Document 10] Japanese Patent Application Publication No. 2020-003289 [Patent Document 11] Japanese Patent Publication No. 2020-012851 [Patent Document 12] Japanese Patent Application Laid-Open No. 2010-048723 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even when the state of the object to be measured is detected by utilizing the generation of eddy currents in the object to be measured, the measurement results of the eddy currents differ depending on the depth of the object to be measured (e.g., rebar) inside the object (e.g., reinforced concrete), making it difficult to detect the state of the object to be measured.

[0008] Therefore, an object of the present invention is to deal with differences in eddy currents depending on the depth of the object being measured when the state of the object being measured is determined based on eddy currents generated by exciting the object inside the object. [Means for solving the problem]

[0009] The state determination device of the present invention comprises an excitation unit that excites a measurement object inside an object, a plurality of magnetic measurement units that measure the magnetic field generated by eddy currents generated in the measurement object, a correspondence relationship recording unit that records the correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement units, and a state determination unit that determines the state of the measurement object based on the measurement results of the magnetic measurement units and the recorded contents of the correspondence relationship recording unit, and is configured so that the recorded contents of the correspondence relationship recording unit are for when the measurement object is placed at a plurality of different depths in the object.

[0010] According to the state determination device configured as described above, the magnetic excitation unit excites the measurement object inside the object. Multiple magnetic measurement units measure magnetic fields generated by eddy currents generated in the measurement object. A correspondence relationship recording unit records the correspondence relationship between the state of the measurement object and data based on the measurement results of the magnetic measurement units. A state determination unit determines the state of the measurement object based on the measurement results of the magnetic measurement units and the recorded contents of the correspondence relationship recording unit. The recorded contents of the correspondence relationship recording unit are for cases where the measurement object is placed at multiple depths in the object.

[0011] In addition, in the state determination device of the present invention, the correspondence recording unit may record the correspondence between the state of the object to be measured and the depth of the object to be measured and the data, the state determination unit may determine the state of the object to be measured according to the known depth of the object to be measured, and the data may be the measurement result of the magnetic measurement unit.

[0012] In addition, in the state determination device of the present invention, the correspondence recording unit may record the correspondence between the state of the measurement object and the data, and the data may be obtained by multivariate analysis of the measurement results of the magnetic measurement unit.

[0013] In addition, in the state determination device of the present invention, the correspondence recording unit may record the correspondence between the state of the object to be measured and the depth of the object to be measured, and the data, the state determination unit may determine the state of the object to be measured and further measure the depth of the object to be measured, and the data may be obtained by multivariate analysis of the measurement results of the magnetic measurement unit.

[0014] In the state determination device according to the present invention, the correspondence relationship may be obtained by machine learning using the state of the measurement object and the measurement results of the magnetic measurement unit as training data.

[0015] In addition, in the state determination device of the present invention, the correspondence may be obtained by machine learning using the state of the object to be measured, the depth of the object to be measured, and the measurement results of the magnetic measurement unit as training data.

[0016] The state determination device according to the present invention may be configured so that the correspondence relationship differs depending on the depth of the measurement object.

[0017] In the state determination device according to the present invention, the object may be reinforced concrete, and the measurement target may be reinforcing bars.

[0018] In the condition determination device according to the present invention, the condition may be determined as whether or not the reinforcing bar is corroded.

[0019] In the state determination device according to the present invention, the state may be determined as whether or not the reinforcing bar is broken.

[0020] The state determination device according to the present invention may measure the position of the reinforcing bar based on the measurement result of the magnetic measurement unit.

[0021] The state determination device according to the present invention may measure the diameter or radius of the reinforcing bar based on the measurement result of the magnetic measurement unit.

[0022] In the state determining device according to the present invention, the state determining unit may determine the state of the measurement object based on part of the measurement results of the magnetic measurement unit.

[0023] The present invention is a state determination method comprising an excitation step of exciting a measurement object inside an object, a plurality of magnetic measurement steps of measuring magnetic fields generated by eddy currents generated in the measurement object, a correspondence recording step of recording the correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement steps, and a state determination step of determining the state of the measurement object based on the measurement results of the magnetic measurement steps and the recorded contents of the correspondence recording step, wherein the recorded contents of the correspondence recording step are for when the measurement object is placed at a plurality of different depths in the object.

[0024] The present invention is a program for causing a computer to execute a state determination process in a state determination device having an excitation unit that excites a measurement object inside an object and a plurality of magnetic measurement units that measure magnetic fields generated by eddy currents generated in the measurement object, wherein the state determination process comprises a correspondence relationship recording step that records the correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement units, and a state determination step that determines the state of the measurement object based on the measurement results of the magnetic measurement units and the recorded contents of the correspondence relationship recording step, and the recorded contents of the correspondence relationship recording step are for cases where the measurement object is positioned at a plurality of different depths in the object.

[0025] The present invention is a computer-readable recording medium having recorded thereon a program for causing a computer to execute a state determination process in a state determination device having an excitation unit that excites a measurement object inside an object and a plurality of magnetic measurement units that measure magnetic fields generated by eddy currents generated in the measurement object, wherein the state determination process comprises a correspondence relationship recording step that records the correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement units, and a state determination step that determines the state of the measurement object based on the measurement results of the magnetic measurement units and the recorded contents of the correspondence relationship recording step, and the recorded contents of the correspondence relationship recording step are for cases where the measurement object is positioned at a plurality of different depths in the object. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a functional block diagram showing a configuration of a state determination device 1 according to a first embodiment of the present invention. [Figure 2] 2(a) shows a side view of reinforced concrete (object) 2, and FIG. 2(b) shows a cross-sectional view of the reinforced concrete (object) 2. [Figure 3] 3(a) is a front view of a state in which a substrate 1s of the state determination device 1 is attached to a reinforced concrete (object) 2, and FIG. 3(b) is a plan view of the substrate 1s of the state determination device 1. FIG. [Figure 4] This figure shows the magnetic field MF generated by the magnetic excitation unit 1a and the eddy current EC generated by the magnetic field MF when the depth of the healthy reinforcing bar 2a is shallow (depth d1) (Figure 4(a)) and when the depth of the healthy reinforcing bar 2a is deep (depth d2) (Figure 4(b)). [Figure 5] FIG. 10 is a diagram showing the magnetic field MF generated by the magnetic excitation unit 1a and the eddy current EC generated by the magnetic field MF when the depth of the reinforcing bar 2a is shallow (depth d1) and corrosion 2c exists. [Figure 6] 10 is a diagram for explaining the determination of the state of the measurement target (reinforcing bar 2a) by a state determination unit 1e according to the second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0028] First embodiment 1 is a functional block diagram showing the configuration of a state determination device 1 according to a first embodiment of the present invention. The state determination device 1 according to the first embodiment includes a magnetic excitation unit 1a, a magnetic measurement unit 1b, an excitation signal generation unit 1c, a correspondence relationship recording unit 1d, and a state determination unit 1e.

[0029] 2A and 2B are a side view (FIG. 2A) and a cross-sectional view (FIG. 2B) of a reinforced concrete (object) 2. Referring to FIG. 2A, the reinforced concrete 2 has reinforcing bars 2a and concrete 2b, and the reinforcing bars 2a are arranged inside the reinforced concrete 2.

[0030] The magnetic excitation unit 1a excites the measurement target inside the object. As an example of the object and the measurement target, in the embodiment of the present invention, the object is reinforced concrete 2 and the measurement target is reinforcing bar 2a.

[0031] FIG. 3(a) is a front view of the state determination device 1 with the substrate 1s attached to the reinforced concrete (object) 2, and FIG. 3(b) is a plan view of the substrate 1s of the state determination device 1.

[0032] Referring to FIG. 3(a), a substrate 1s of the condition determination device 1 is attached to a surface (for example, the bottom surface) of reinforced concrete 2. However, an excitation unit 1a and a magnetic measurement unit 1b are arranged on the substrate 1s (see FIG. 3(b)). Note that an excitation signal generation unit 1c, a correspondence relationship recording unit 1d, and a condition determination unit 1e are arranged at positions away from the substrate 1s.

[0033] Referring to FIG. 3(b), the excitation unit 1a is, for example, an elliptical excitation coil. However, the shape of the excitation coil is not limited to an elliptical shape, and it may be circular, rectangular, or linear. Also, referring to FIG. 3(b), the excitation unit 1a is one excitation coil, but there may be multiple excitation coils. In this case, the excitation frequencies of the multiple excitation coils may be the same, but they do not have to be the same.

[0034] The magnetic measurement unit 1b measures the magnetic field generated by the eddy current EC generated in the rebar (measurement object) 2a. Multiple magnetic measurement units 1b are provided. The magnetic measurement units 1b perform Fourier transform or detection using an excitation signal to output the amplitude and phase of a signal based on the magnetic field as the measurement result. However, the amplitude and phase are only examples of the measurement result, and the following t values ​​can also be considered as measurement results.

[0035]

number

[0036] In an embodiment of the present invention, the magnetic measurement unit 1b is a magnetic sensor. The magnetic measurement unit (magnetic sensor) 1b measures, for example, three-axis (X, Y, and Z axes) magnetic fields (see FIG. 3), but may also measure two-axis or one-axis magnetic fields. Note that the magnetic measurement unit 1b does not have to be a magnetic sensor, and may be a coil that measures magnetism. The X-axis direction is the longitudinal direction of the reinforcing bar 2a, the Z-axis direction is the direction perpendicular to the paper surface of FIG. 3(b), and the Y-axis direction is the direction perpendicular to the X-axis and Z-axis.

[0037] Referring to FIG. 3(b), multiple magnetic measurement units (magnetic sensors) 1b are arranged on the substrate 1s at equal intervals in the vertical direction (Y-axis direction) and at equal intervals in the horizontal direction (X-axis direction). An excitation unit (excitation coil) 1a is arranged directly above the central magnetic measurement unit 1b. Although the description "equally spaced" vertically and horizontally, they do not have to be equally spaced. Furthermore, the magnetic measurement units 1b may be arranged on a straight line (for example, in the X-axis or Y-axis direction) or three-dimensionally (for example, in the X-, Y-, and Z-axis directions). Furthermore, the magnetic measurement units 1b may be arranged on concentric circles.

[0038] Figure 4 shows the magnetic field MF generated by the magnetic excitation unit 1a and the eddy current EC generated by the magnetic field MF when the depth of the sound reinforcing bar 2a is shallow (depth d1) (Figure 4(a)) and when the depth of the sound reinforcing bar 2a is deep (depth d2) (Figure 4(b)). Note that in Figure 4, the reinforcing bar 2a is assumed to be sound (i.e., not corroded or broken).

[0039] 4, a magnetic field MF is applied to a reinforcing bar 2a by a magnetic excitation unit 1a. This magnetic field MF generates an eddy current EC in the reinforcing bar 2a. A magnetic measurement unit 1b measures the magnetic field generated by the eddy current EC.

[0040] As shown in Figure 4(a), when the depth of the reinforcing bar 2a is shallow (depth d1), the magnetic field lines of the magnetic field MF generated by the magnetic excitation unit 1a do not spread much in the X-axis direction, but rise almost directly upward (in the Z-axis direction) from the magnetic excitation unit 1a, enter the reinforcing bar 2a, and then extend in the X-axis direction. Therefore, the X-coordinate of the eddy current EC is close to the X-coordinate of the magnetic excitation unit 1a. Therefore, the magnetic field generated by the eddy current EC is also measured strongly by the magnetic measurement unit 1b, which is close to the magnetic excitation unit 1a.

[0041] As shown in Figure 4(b), when the reinforcing bar 2a is deep (depth d2), the magnetic field lines of the magnetic field MF generated by the magnetic excitation unit 1a spread widely in the X-axis direction before entering the reinforcing bar 2a and extending in the X-axis direction. Therefore, the X-coordinate of the eddy current EC is far from the X-coordinate of the magnetic excitation unit 1a. Therefore, the magnetic field generated by the eddy current EC is also measured to a large extent by the magnetic measurement unit 1b, which is far from the magnetic excitation unit 1a.

[0042] FIG. 5 is a diagram showing the magnetic field MF generated by the magnetic excitation unit 1a and the eddy current EC generated by the magnetic field MF when the depth of the reinforcing bar 2a is shallow (depth d1) and corrosion 2c exists.

[0043] When corrosion 2c is present on the rebar 2a, the conductivity of the corrosion 2c is lower than that of the sound portion of the rebar 2a. Furthermore, the relative permeability is generally lower than that of the sound portion of the rebar 2a, although this depends on the corrosion products generated in the corrosion 2c. Therefore, when a magnetic field MF is applied to the rebar 2a by the excitation unit 1a, the intensity of the eddy current EC generated on the surface of the corrosion 2c is lower than that of the sound portion of the rebar 2a. As a result, the magnetic field generated by the eddy current EC on the surface of the corrosion 2c measured by the magnetic measurement unit 1b has a lower magnetic field amplitude and a smaller phase delay than that of a sound portion of the rebar 2a.

[0044] Here, as shown in Fig. 5, when the X coordinate of the corrosion 2c is close to the X coordinate of the magnetic excitation unit 1a, the strength of the eddy current EC is low on the surface of the corrosion 2c and is high in parts far from the X coordinate of the magnetic excitation unit 1a. That is, as shown in Fig. 5, when the X coordinate of the corrosion 2c is close to the X coordinate of the magnetic excitation unit 1a, even though the depth of the reinforcing bar 2a is shallow (depth d1), the magnetic field generated by the eddy current EC is measured as being large by the magnetic measurement unit 1b, which is far from the magnetic excitation unit 1a.

[0045] Therefore, just because the magnetic field generated by the eddy current EC is measured as being large at the magnetic measurement unit 1b, which is far from the excitation unit 1a, does not necessarily mean that the depth of the reinforcing bar 2a is deep (Figure 4(b)) (the reinforcing bar 2a is sound), and it may also be that the depth of the reinforcing bar 2a is shallow (Figure 5) (the reinforcing bar 2a has corrosion 2c).

[0046] The same can be said even if the corroded portion 2c is broken rather than corroded.

[0047] The excitation signal generating unit 1c provides an excitation signal (for example, an electric signal) to the excitation unit 1a.

[0048] The correspondence recorder 1d records the correspondence between the state of the measurement object (reinforcing bar 2a), the depth of the measurement object (reinforcing bar 2a), and data based on the measurement results of the magnetic measurement unit 1b. However, the data is the measurement results of the magnetic measurement unit 1b. Furthermore, the contents recorded by the correspondence recorder 1d are for cases where the measurement object is placed at multiple depths in the object (reinforced concrete 2). Furthermore, the state of the measurement object is whether or not the reinforcing bar 2a is corroded (or broken).

[0049] For example, the correspondence relationship recording unit 1d records the measurement results (e.g., amplitude and phase) of the magnetic measurement unit 1b when the reinforcing bar 2a is not corroded (i.e., is sound) and the reinforcing bar 2a is at depths d1 and d2 (see FIGS. 4(a) and 4(b)). Note that the correspondence relationship recording unit 1d may record the measurement results of the magnetic measurement unit 1b for three or more depths of the reinforcing bar 2a, not limited to two depths d1 and d2.

[0050] The state determination unit 1e determines the state of the measurement object (reinforcing bar 2a) based on the measurement results of the magnetic measurement unit 1b, the recorded contents of the correspondence recorder 1d, and the known depth of the measurement object (reinforcing bar 2a).

[0051] The state determination unit 1e may determine the state of the reinforcing bar 2a based on part of the measurement results of the magnetic measurement unit 1b. For example, the state determination unit 1e may determine the state of the reinforcing bar 2a based on only the measurement results of the magnetic measurement unit 1b for one row (X direction) directly below the reinforcing bar 2a.

[0052] The state determination unit 1e may measure the position (e.g., XY coordinates) of the reinforcing bar 2a based on the measurement results of the magnetic measurement unit 1b. When the magnetic measurement unit 1b is positioned directly below the reinforcing bar 2a, the magnetic field generated by the eddy current EC becomes large, and therefore the position of the reinforcing bar 2a can be measured.

[0053] Furthermore, the state determination unit 1e may measure the diameter or radius of the reinforcing bar 2a based on the measurement results of the magnetic measurement unit 1b. The smaller the diameter of the reinforcing bar 2a, the lower the intensity of the eddy current EC generated on the surface of the reinforcing bar 2a, so the diameter or radius of the reinforcing bar 2a can be measured.

[0054] Next, the operation of the first embodiment will be described.

[0055] First, the substrate 1s of the condition determination device 1 is attached to the bottom surface of the reinforced concrete 2 (see FIG. 3(a)). When the excitation signal generating unit 1c gives an excitation signal to the exciting unit 1a, the exciting unit 1a excites the reinforcing bar 2a (magnetic field MF), and an eddy current EC is generated on the surface of the reinforcing bar 2a.

[0056] Furthermore, the circuit board 1s of the condition determination device 1 (see Figure 3(b)) is scanned in the X-axis direction and the Y-axis direction, and the circuit board 1s of the condition determination device 1 is positioned so that the magnitude of the magnetic field measured by the magnetic measurement unit 1b (i.e., the magnetic field generated by the eddy current EC generated in the reinforcing bar 2a) is approximately maximized (i.e., so that the circuit board 1s of the condition determination device 1 is positioned almost directly below the reinforcing bar 2a).

[0057] For example, suppose that the correspondence recorder 1d records the measurement results (e.g., amplitude) of the magnetic measurement unit 1b when the depth of the sound rebar 2a is d1 and d2 (see FIGS. 4(a) and 4(b)). Furthermore, suppose that the measurement results of the magnetic measurement unit 1b correspond to the case where the depth of the sound rebar 2a is d2 (when the X coordinate of the eddy current EC is far from the X coordinate of the excitation unit 1a). In other words, suppose that the magnetic field generated by the eddy current EC is measured to be large by the magnetic measurement unit 1b, which is far from the excitation unit 1a.

[0058] In such a case, if it is known that the depth of the reinforcing bar 2a is d2, the condition determining unit 1e determines that the reinforcing bar 2a is sound (see FIG. 4(b)). On the other hand, if it is known that the depth of the reinforcing bar 2a is d1, the condition determining unit 1e determines that the reinforcing bar 2a is corroded (see FIG. 5).

[0059] According to the first embodiment, the recorded contents of the correspondence recording unit 1d are for the case where the reinforcing bars 2a are arranged at a plurality of depths d1 and d2 (see FIGS. 4(a) and 4(b)) in the reinforced concrete 2. Therefore, when the state of the reinforcing bars 2a (presence or absence of corrosion or fracture) is determined according to the eddy current EC generated by exciting the reinforcing bars 2a inside the reinforced concrete 2, it is possible to deal with the difference in eddy current EC depending on the depths d1 and d2 of the reinforcing bars 2a in the reinforced concrete 2 (see FIGS. 4(a) and 4(b)).

[0060] Second embodiment The state determining device 1 according to the second embodiment differs from the first embodiment in that the data based on the measurement results of the magnetic measurement unit 1b is obtained by multivariate analysis of the measurement results of the magnetic measurement unit 1b.

[0061] The state determination device 1 according to the second embodiment includes an excitation unit 1a, a magnetic measurement unit 1b, an excitation signal generation unit 1c, a correspondence relationship recording unit 1d, and a state determination unit 1e. Hereinafter, parts similar to those in the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0062] The magnetic excitation unit 1a, magnetic measurement unit 1b, and excitation signal generation unit 1c are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0063] The correspondence recorder 1d records the correspondence between the state of the measurement target (rebar 2a) and data based on the measurement results of the magnetic measurement unit 1b. However, the data is obtained by performing multivariate analysis (for example, principal component analysis) on the measurement results of the magnetic measurement unit 1b. Other aspects of the correspondence recorder 1d are the same as those of the first embodiment, and therefore a description thereof will be omitted.

[0064] The state determination unit 1e is the same as in the first embodiment. Below, a specific example of determination by the state determination unit 1e will be described in the case where the measurement results of the magnetic measurement unit 1b are used as data obtained by principal component analysis, and the correspondence between the data and the state of the reinforcing bar 2a is recorded in the correspondence recorder 1d.

[0065] Principal component analysis is also used in image compression, and principal component analysis in image compression is applied to an embodiment of the present invention. The channel (CH) mapping of the amplitude and phase of a magnetic field-based signal measured by the magnetic measurement unit 1b can be considered a type of image. Therefore, the image compression technique can be applied directly to the measurement results by the magnetic measurement unit 1b.

[0066] As an example, we will show a case where principal component analysis is applied to the amplitude of a signal based on the magnetic field in the X, Y, and Z axis directions. A matrix D storing the amplitudes in the X, Y, and Z axis directions is defined as shown in the following equation (1).

[0067]

number

[0068]

number

[0069] FIG. 6 is a diagram for explaining the determination of the state of the measurement target (reinforcing bar 2a) by the state determination unit 1e according to the second embodiment.

[0070] First, the first and second principal components when the reinforcing bar 2a is at a depth a, b, or c (for example, a = 20 mm, b = 40 mm, c = 60 mm, but this is not particularly limited) in cases where the reinforcing bar 2a is sound and when the reinforcing bar 2a is corroded are plotted on a graph with the first principal component on the horizontal axis and the second principal component on the vertical axis. Based on this plot, a support vector machine generates a boundary line 4. The area above the boundary line 4 is determined to be sound, and the area below the boundary line 4 is determined to be corroded.

[0071] Next, the operation of the second embodiment will be described.

[0072] First, the substrate 1s of the condition determination device 1 is attached to the bottom surface of the reinforced concrete 2 (see FIG. 3(a)). When the excitation signal generating unit 1c gives an excitation signal to the exciting unit 1a, the exciting unit 1a excites the reinforcing bar 2a (magnetic field MF), and an eddy current EC is generated on the surface of the reinforcing bar 2a.

[0073] Furthermore, the circuit board 1s of the condition determination device 1 (see Figure 3(b)) is scanned in the X-axis direction and the Y-axis direction, and the circuit board 1s of the condition determination device 1 is positioned so that the magnitude of the magnetic field measured by the magnetic measurement unit 1b (i.e., the magnetic field generated by the eddy current EC generated in the reinforcing bar 2a) is approximately maximized (i.e., so that the circuit board 1s of the condition determination device 1 is positioned almost directly below the reinforcing bar 2a).

[0074] Furthermore, the correspondence relationship recording unit 1d records the first and second principal components when the reinforcing bar 2a is at a depth a, b, or c in the cases where the reinforcing bar 2a is sound and where the reinforcing bar 2a is corroded (see FIG. 6). However, it is not necessary to record the depths a, b, and c in the correspondence relationship recording unit 1d.

[0075] Here, the state determination unit 1e generates a boundary line 4 (see FIG. 6) from the contents recorded in the correspondence relationship recording unit 1d.

[0076] Furthermore, the condition determination unit 1e receives the measurement results of the magnetic measurement unit 1b and calculates the first and second principal components. Whether the reinforcing bar 2a is sound or corroded is determined depending on whether the first and second principal components are plotted on the graph in Figure 6 and are above or below the boundary line 4.

[0077] According to the second embodiment, the contents recorded in the correspondence recording unit 1d are for the case where the reinforcing bars 2a are arranged at a plurality of depths a, b, and c (see FIG. 6) in the reinforced concrete 2. Therefore, when the state of the reinforcing bars 2a (presence or absence of corrosion or fracture) is determined according to the eddy current EC generated by exciting the reinforcing bars 2a inside the reinforced concrete 2, it is possible to deal with differences in the eddy current EC depending on the depth of the reinforcing bars 2a in the reinforced concrete 2.

[0078] Moreover, according to the second embodiment, the state determination unit 1e determines whether the reinforcing bar 2a is sound or corroded depending on whether the plot of the first principal component and the second principal component of the measurement results of the magnetic measurement unit 1b is above or below the boundary line 4 (see Figure 6), so there is no particular need for the depth of the reinforcing bar 2a to be known.

[0079] The second embodiment may be modified as follows.

[0080] <Modification> In a modified example of the second embodiment, the correspondence recording unit 1d records the correspondence between the condition and depth of the reinforcing bar 2a and data based on the measurement results of the magnetic measurement unit 1b (multivariate analysis of the measurement results of the magnetic measurement unit 1b).

[0081] For example, the correspondence relationship recording unit 1d records the first and second principal components when the reinforcing bar 2a is sound and when it is corroded and when the reinforcing bar 2a is at a depth a, b, or c (see FIG. 6). Moreover, the correspondence relationship recording unit 1d also records the depths a, b, and c.

[0082] The state determination unit 1e determines the state of the reinforcing bar 2a, as in the second embodiment. Furthermore, the state determination unit 1e measures the depth of the reinforcing bar 2a. For example, the state determination unit 1e determines the depth of the reinforcing bar 2a based on whether the plot of the first and second principal components of the measurement results of the magnetic measurement unit 1b on the graph of FIG. 6 is closest to the plot of depth a, b, or c. For example, if the plot of the first and second principal components on the graph of FIG. 6 is closest to the plot of depth a, the depth of the reinforcing bar 2a is determined to be a.

[0083] Third embodiment The state determination device 1 according to the third embodiment differs from the first embodiment in that the correspondences recorded in the correspondence recording unit 1d are obtained by machine learning.

[0084] The state determination device 1 according to the third embodiment includes an excitation unit 1a, a magnetic measurement unit 1b, an excitation signal generation unit 1c, a correspondence relationship recording unit 1d, and a state determination unit 1e. Hereinafter, parts similar to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0085] The magnetic excitation unit 1a, magnetic measurement unit 1b, and excitation signal generation unit 1c are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0086] The correspondence recording unit 1d records the correspondence between the state of the measurement target (reinforcing bar 2a) and data based on the measurement results of the magnetic measurement unit 1b (for example, the measurement results of the magnetic measurement unit 1b). However, the correspondence is obtained by machine learning using the state of the reinforcing bar 2a and the measurement results of the magnetic measurement unit 1b as training data. Note that, as in the first embodiment, the recorded contents of the correspondence recording unit 1d are for cases where the reinforcing bar 2a is placed at multiple depths in the reinforced concrete 2.

[0087] Machine learning methods that can be used include convolutional neural networks (CNNs), neural networks, and other well-known machine learning methods.

[0088] For example, when a convolutional neural network (CNN) is used as a machine learning method, the decision model comprises an input layer, a convolutional layer, a pooling layer, a fully connected layer, and an output layer. n x m x 6 data is input to the input layer. Here, 6 refers to the amplitude and phase for three axes. However, it is also possible to input only some of the phases and amplitudes for the X, Y, and Z axes to the input layer, rather than all of them.

[0089] When the measurement results of the magnetic measurement unit 1b are given to the input layer, the output of the input layer is given to the convolution layer, the output of the convolution layer is given to the pooling layer, the output of the pooling layer is given to the fully connected layer, and the output of the fully connected layer is given to the output layer. The condition of the measurement target (rebar 2a) (whether it is healthy or corroded) is output from the output layer.

[0090] The activation function of the output layer is a sigmoid function. However, a Softmax function may also be used as the activation function of the output layer, which results in a multi-value output, allowing the output of the degree of corrosion (for example, heavy corrosion, medium corrosion, or light corrosion).

[0091] The state determination unit 1e determines the state of the reinforcing bar 2a based on the measurement results of the magnetic measurement unit 1b and the recorded contents of the correspondence relationship recording unit 1d.

[0092] Next, the operation of the third embodiment will be described.

[0093] First, the substrate 1s of the condition determination device 1 is attached to the bottom surface of the reinforced concrete 2 (see FIG. 3(a)). When the excitation signal generating unit 1c gives an excitation signal to the exciting unit 1a, the exciting unit 1a excites the reinforcing bar 2a (magnetic field MF), and an eddy current EC is generated on the surface of the reinforcing bar 2a.

[0094] Furthermore, the circuit board 1s of the condition determination device 1 (see Figure 3(b)) is scanned in the X-axis direction and the Y-axis direction, and the circuit board 1s of the condition determination device 1 is positioned so that the magnitude of the magnetic field measured by the magnetic measurement unit 1b (i.e., the magnetic field generated by the eddy current EC generated in the reinforcing bar 2a) is approximately maximized (i.e., so that the circuit board 1s of the condition determination device 1 is positioned almost directly below the reinforcing bar 2a).

[0095] The state determination unit 1e receives the measurement results of the magnetic measurement unit 1b and reads out the state of the reinforcing bar 2a corresponding to the measurement results of the magnetic measurement unit 1b from the contents recorded in the correspondence relationship recording unit 1d.

[0096] According to the third embodiment, the contents recorded in the correspondence recording unit 1d are for cases where the reinforcing bars 2a are arranged at a plurality of depths in the reinforced concrete 2. Therefore, when the state of the reinforcing bars 2a (presence or absence of corrosion or fracture) is determined based on the eddy current EC generated by exciting the reinforcing bars 2a inside the reinforced concrete 2, it is possible to deal with differences in the eddy current EC depending on the depth of the reinforcing bars 2a in the reinforced concrete 2.

[0097] Moreover, according to the third embodiment, it is not particularly necessary for the depth of the reinforcing bar 2a to be known.

[0098] The third embodiment may be modified as follows.

[0099] <Variation 1> In the first modification of the third embodiment, the correspondence recorded by the correspondence recording unit 1d is obtained by machine learning using the state of the reinforcing bar 2a, the depth of the reinforcing bar 2a, and the measurement results of the magnetic measurement unit 1b as training data, which allows the state determination unit 1e to measure the depth of the reinforcing bar 2a.

[0100] <Variation 2> In the second modification of the third embodiment, different correspondence relationships are recorded depending on the depth of the reinforcing bars 2a. For example, different correspondence relationships are recorded for depths of the reinforcing bars 2a of 0 to 20 mm, 20 to 40 mm, and over 40 mm. This improves the accuracy of the correspondence relationships obtained by machine learning.

[0101] The above embodiment can be realized as follows: A computer equipped with a CPU, a hard disk, and a media (USB memory, CD-ROM, etc.) reader reads media containing programs for implementing the above-mentioned components, such as the correspondence recording unit 1d and the status determination unit 1e, and installs the programs onto the hard disk. This method also realizes the above-mentioned functions. [Explanation of symbols]

[0102] 1. Status determination device 1a Excitation part 1b Magnetic measurement section 1c Excitation signal generator 1d Correspondence Recording Section 1e Status determination section 1s board 2. Reinforced concrete (object) 2a Rebar (measurement object) 2b Concrete 2c Corrosion 4. Boundaries MF magnetic field EC eddy current d1, d2, a, b, c depth

Claims

1. an excitation unit that excites a measurement target inside the object; a plurality of magnetic measurement units for measuring magnetic fields generated by eddy currents generated in the measurement object; a correspondence recorder that records a correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement unit; a state determination unit that determines a state of the measurement object based on the measurement result of the magnetic measurement unit and the recorded contents of the correspondence relationship recording unit; Equipped with The recorded contents of the correspondence relationship recording unit are for a case where the measurement target is disposed at a plurality of depths in the object. Status determination device.

2. The state determination device according to claim 1, the correspondence relationship recording unit records a correspondence relationship between the state of the measurement object and the depth of the measurement object, and the data; the state determination unit determines the state of the measurement object according to the known depth of the measurement object; The data is a measurement result of the magnetic measurement unit. Status determination device.

3. The state determination device according to claim 1, the correspondence recorder records the correspondence between the state of the measurement object and the data; The data is obtained by multivariate analysis of the measurement results of the magnetic measurement unit. Status determination device.

4. The state determination device according to claim 1, the correspondence relationship recording unit records a correspondence relationship between the state of the measurement object and the depth of the measurement object, and the data; the state determination unit determines the state of the measurement object and further measures the depth of the measurement object; The data is obtained by multivariate analysis of the measurement results of the magnetic measurement unit. Status determination device.

5. The state determination device according to claim 1, The correspondence relationship is obtained by machine learning using the state of the measurement object and the measurement result of the magnetic measurement unit as training data. Status determination device.

6. The state determination device according to claim 1, The correspondence relationship is obtained by machine learning using the state of the measurement object, the depth of the measurement object, and the measurement result of the magnetic measurement unit as training data. Status determination device.

7. The state determination device according to claim 6, The correspondence relationship is set to be different depending on the depth of the measurement object. Status determination device.

8. The state determination device according to any one of claims 1 to 7, the object is reinforced concrete, The measurement object is a reinforcing bar. Status determination device.

9. The state determination device according to claim 8, The condition is whether the rebar is corroded or not. Status determination device.

10. The state determination device according to claim 8, The state is whether the rebar is broken or not. Status determination device.

11. The state determination device according to claim 8, Measure the position of the reinforcing bar based on the measurement result of the magnetic measurement unit. Status determination device.

12. The state determination device according to claim 8, Measure the diameter or radius of the reinforcing bar based on the measurement result of the magnetic measurement unit. Status determination device.

13. The state determination device according to any one of claims 1 to 7, A state determination device in which the state determination unit determines the state of the measurement object based on a portion of the measurement results of the magnetic measurement unit.

14. an excitation step of exciting a measurement target inside the object; a plurality of magnetic measurement steps for measuring a magnetic field generated by an eddy current generated in the measurement object; a correspondence recording step of recording a correspondence between the state of the measurement object and data based on the measurement result of the magnetic measurement step; a state determination step of determining a state of the measurement object based on the measurement result of the magnetic measurement step and the recorded content of the correspondence relationship recording step; Equipped with The recorded content of the correspondence relationship recording step is for a case where the measurement target is disposed at a plurality of depths in the object. Status determination method.

15. A program for causing a computer to execute a state determination process in a state determination device having a magnetic excitation unit that excites a measurement target inside an object and a plurality of magnetic measurement units that measure magnetic fields generated by eddy currents generated in the measurement target, The state determination process a correspondence recording step of recording a correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement unit; a state determination step of determining a state of the measurement object based on the measurement result of the magnetic measurement unit and the contents recorded in the correspondence relationship recording step; Equipped with The recorded content of the correspondence relationship recording step is for a case where the measurement target is disposed at a plurality of depths in the object. program.

16. A computer-readable recording medium having recorded thereon a program for causing a computer to execute a state determination process in a state determination device having a magnetic excitation unit that excites a measurement target inside an object and a plurality of magnetic measurement units that measure magnetic fields generated by eddy currents generated in the measurement target, The state determination process a correspondence recording step of recording a correspondence between the state of the measurement object and data based on the measurement results of the magnetic measurement unit; a state determination step of determining a state of the measurement object based on the measurement result of the magnetic measurement unit and the contents recorded in the correspondence relationship recording step; Equipped with The recorded content of the correspondence relationship recording step is for a case where the measurement target is disposed at a plurality of depths in the object. Recording medium.

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