JP7159926B2 - Apparatus and method for inspecting concrete panels with embedded metal - Google Patents

Description

The present invention relates to techniques for inspecting concrete panels in which metal is embedded.

A destructive test must be performed to confirm the position of the rebar embedded in the concrete panel. However, once destructive testing is done, the destroyed concrete panel cannot be used as a product. Therefore, non-destructive inspection using an eddy current sensor is generally performed (see Patent Documents 1 to 5).

In this non-destructive inspection, it is usually estimated that the rebar is present at the position corresponding to the peak of the output waveform of the eddy current sensor. Specifically, the eddy current sensor is configured to output a value corresponding to the distance between the eddy current sensor and the reinforcing bar. An inspection apparatus using an eddy current sensor is configured to arrange the values output by the eddy current sensor in time series, form a waveform, and recognize the position of the reinforcing bar based on the position of the peak in the waveform.

Japanese Patent No. 5146673 JP 2018-132426 A JP 2018-9862 A Japanese Patent No. 5241200 JP 2009-109304 A

However, if there is another rebar in the vicinity of the rebar being inspected, the eddy current sensor may be affected by the eddy currents generated by the other rebar. Therefore, an inspection device using an eddy current sensor may not be able to accurately recognize the position of the reinforcing bar being inspected.

Therefore, it is desirable to provide a device that can more accurately identify the location of metal embedded in concrete panels.

An apparatus according to an embodiment of the present invention is an apparatus for inspecting a concrete panel in which metal is embedded, comprising an eddy current sensor, a movement mechanism for moving the eddy current sensor relative to the concrete panel, and an arithmetic device, wherein the arithmetic device estimates the position of the metal in the concrete panel based on the position of the peak of the output waveform of the eddy current sensor, and the peak of the output waveform of the eddy current sensor. It is configured to correct the estimated position of the metal based on the shape.

The device described above can more accurately identify the location of metal embedded in concrete panels.

1 is a perspective view of a concrete panel in which reinforcing bars are embedded; FIG. 2 is a partial cross-sectional view of the concrete panel of FIG. 1; FIG. It is a functional block diagram which shows the structural example of an inspection apparatus. FIG. 4 is a diagram showing an example of the trajectory of an eddy current sensor relatively moving on a concrete panel conveyed by a conveyor; FIG. 4 is a diagram showing an example of an output waveform of an eddy current sensor passing over a portion where one reinforcing bar is embedded; FIG. 10 is a diagram showing an example of an output waveform of an eddy current sensor passing over a portion where two reinforcing bars are embedded side by side; 7 is an enlarged view of a part of FIG. 6; FIG. FIG. 4 is a diagram showing details of an output waveform of an eddy current sensor; It is a figure which shows the relationship between inclination ratio and correction amount. 9 is a flowchart of fogging thickness estimation processing;

First, an inspection apparatus 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. The inspection device 100 is configured to inspect a concrete panel in which metal is embedded. FIG. 1 is a perspective view of a concrete panel 11 to be inspected by an inspection device 100. FIG. FIG. 2 is a partial cross-sectional view of the concrete panel 11 on a virtual vertical plane (XZ plane) including the dashed-dotted line L1 in FIG. FIG. 3 is a functional block diagram of the inspection device 100. As shown in FIG. FIG. 4 is a diagram showing the positional relationship between the concrete panel 11 transported by the inspection apparatus 100 and the eddy current sensor 51. As shown in FIG. Specifically, FIG. 4A is a top view of the concrete panel 11 and the eddy current sensor 51, and FIG. 4B is a side view of the concrete panel 11 and the eddy current sensor 51. FIG. A region MR indicated by a dot pattern in FIG. 4B represents the detection range of the eddy current sensor 51 .

As shown in FIG. 1, reinforcing bars 12 are embedded in the concrete panel 11 . Specifically, in the concrete panel 11, long reinforcing bars 12L as main bars parallel to the long sides of the concrete panel 11 and short reinforcing bars 12S as horizontal reinforcing bars parallel to the short sides of the concrete panel 11 are embedded. ing. In the example of FIG. 1, the long reinforcing bar 12L includes three long reinforcing bars 12L1-12L3, and the short reinforcing bar 12S includes five short reinforcing bars 12S1-12S5.

The positions of the reinforcing bars 12 embedded in the concrete panel 11 are determined by manufacturing conditions. However, after the reinforcing bars 12 are embedded in the concrete panel 11, the inspector cannot directly confirm the position of the reinforcing bars 12 unless the concrete panel 11 is destroyed.

Therefore, the inspection device 100 according to the embodiment of the present invention uses the eddy current sensor 51 to indirectly and automatically confirm the position of the reinforcing bar 12 . Specifically, the inspection device 100 is configured to inspect whether or not the reinforcing bars 12 are embedded at appropriate positions within the concrete panel 11 . More specifically, the inspection apparatus 100 is configured to estimate the cover thickness CT, which is the distance from the +X side end surface 11S of the concrete panel 11 to the short reinforcing bar 12S1. Note that the cover thickness CT may be estimated as the distance from the +X side end surface 11S of the concrete panel 11 to the center of the short reinforcing bar 12S1.

FIG. 3 is a functional block diagram of the inspection device 100. As shown in FIG. The inspection device 100 mainly includes an arithmetic device 50, an eddy current sensor 51, a moving mechanism 52, a display device 53, a sound output device 54, and the like.

The display device 53 is configured to display information about the inspection device 100 . In this embodiment, the display device 53 is a liquid crystal display and is configured to display the value of the fogging thickness CT estimated by the inspection device 100 . When the difference between the value of the cover thickness CT estimated by the inspection apparatus 100 and the reference value is greater than or equal to a predetermined value, the display device 53 may display a warning screen to notify that the cover thickness CT is abnormal.

The sound output device 54 is configured to audibly output information about the inspection device 100 . In this embodiment, the sound output device 54 is a speaker, and when the difference between the value of the cover thickness CT estimated by the inspection device 100 and the reference value is equal to or greater than a predetermined value, the sound output device 54 notifies that the cover thickness CT is abnormal. Output a warning sound. The sound output device 54 may output a voice message telling that the fogging thickness CT is abnormal.

The computing device 50 is configured to be able to control the inspection device 100 . In this embodiment, the computing device 50 is a microcomputer including a CPU, a volatile memory device, a nonvolatile memory device, an input/output interface, and the like.

Each function of the arithmetic unit 50 is implemented by the CPU executing a program stored in the nonvolatile storage device. However, each function of the computing device 50 may be realized by hardware or firmware. The computing device 50 has an estimating section 50A and a correcting section 50B as functional elements that perform each function.

The estimating unit 50A is configured to estimate the positions of the reinforcing bars 12 embedded in the concrete panel 1 . In this embodiment, the estimation unit 50A estimates the cover thickness CT, which is the distance from the +X side end surface 11S of the concrete panel 11 to the short reinforcing bar 12S1, based on the peak position of the output waveform of the eddy current sensor 51. It is configured.

The correction unit 50B is configured to correct the positions of the reinforcing bars 12 estimated by the estimation unit 50A. In this embodiment, the correction unit 50B is configured to correct the estimated cover thickness CT of the short reinforcing bar 12S1 based on the peak shape of the output waveform of the eddy current sensor 51. FIG. The peak shape means the shape of the portion including before and after the peak in the output waveform.

The eddy current sensor 51 is configured to detect the position of a conductive object such as metal embedded in the concrete panel 11 without contact. In this embodiment, the eddy current sensor 51 includes an excitation coil and a detection coil, and detects a magnetic field caused by an eddy current generated in the reinforcing bar 12 when the reinforcing bar 12 approaches. It is configured to be able to detect the position of Specifically, the eddy current sensor 51 detects the strength of the magnetic field caused by the eddy current generated in the reinforcing bar 12 as a voltage value, and outputs the voltage value to the computing device 50 . The computing device 50 may be configured to receive the output of a single eddy current sensor 51 or may be configured to receive the outputs of a plurality of eddy current sensors 51 .

The moving mechanism 52 is a mechanism for moving the eddy current sensor 51 relative to the concrete panel 11, and may move only the eddy current sensor 51 or only the concrete panel 1. Both the sensor 51 and the concrete panel 1 may be moved.

In this embodiment, the moving mechanism 52 is composed of a conveyor that moves the concrete panel 1 from the -X side to the +X side along the X axis, as indicated by the arrow AR1 in FIG. 4(A). Conveyors are, for example, belt conveyors, roller conveyors, and the like. The X-axis is parallel to the long sides of the concrete panel 1 and typically extends horizontally. With this configuration, the moving mechanism 52 can move the concrete panel 1 linearly and horizontally at a constant speed.

In this embodiment, as shown in FIG. 4B, the eddy current sensor 51 is fixed at a position above the +Z side surface 11a of the concrete panel 11 that is conveyed through the production line by a predetermined distance. are strategically placed. Therefore, the scanning locus of the eddy current sensor 51 relatively moving on the concrete panel 11 extends from the +X side to the -X side along the X axis as indicated by the dotted line arrow AR2 in FIG. The eddy current sensor 51 may be fixedly arranged at a lower position separated by a predetermined distance from the rear surface of the concrete panel 11 on the -Z side.

However, the moving mechanism 52 may be configured to reciprocate the eddy current sensor 51 along the Y-axis perpendicular to the X-axis. The Y-axis is parallel to the short sides of the concrete panel 1 and typically extends horizontally. This reciprocating mechanism is configured so that the eddy current sensor 51 can reciprocate a predetermined distance by using a known technology such as a linear actuator. The movement range of the reciprocating mechanism is set equal to or larger than the width of the concrete panel 11 .

In this embodiment, as described above, the eddy current sensor 51 can scan the ventral surface 11a of the concrete panel 11 from the +X side end to the −X side end. Therefore, when the reinforcing bar 12 embedded in the concrete panel 11 approaches the eddy current sensor 51, the output value of the eddy current sensor 51 changes. The computing device 50 can acquire an output waveform by continuously receiving this output value.

FIG. 5 shows an example of an output waveform acquired by the computing device 50. As shown in FIG. The computing device 50 acquires an output waveform as shown in FIG. 5 when the eddy current sensor 51 passes over the part of the concrete panel 11 in which one short reinforcing bar 12S is embedded. For example, when the eddy current sensor 51 passes over the portion where the short reinforcing bars 12S1 are embedded in another concrete panel in which the short reinforcing bars 12S2 are not embedded in FIG. get a good output waveform.

In FIG. 5, the vertical axis corresponds to the output value of the eddy current sensor 51, and the horizontal axis corresponds to the distance in the X-axis direction from the end face 11S of the concrete panel 11. As shown in FIG. 5, the output value of the eddy current sensor 51 begins to increase at the position of the distance D1 from the end face 11S, the output value of the eddy current sensor 51 forms a peak P1 at the position of the distance D2 from the end face 11S, and the end face 11S The output value of the eddy current sensor 51 returns to zero at the position of the distance D3 from .

In this case, the estimating unit 50A of the arithmetic device 50 estimates that the short reinforcing bar 12S1 is buried at a position a distance D2 from the end surface 11S where the peak P1 is formed, and estimates the cover thickness CT of the short reinforcing bar 12S1. Derive the distance D2 as a value.

FIG. 6 shows another example of output waveforms acquired by the arithmetic device 50 . Arithmetic device 50 acquires an output waveform as shown in FIG. 6 when eddy current sensor 51 passes over a portion of concrete panel 11 where two short reinforcing bars 12S are buried adjacent to each other. . For example, when the eddy current sensor 51 passes over a portion of the concrete panel 11 in FIG. get a good output waveform. The cover thickness CT of the short reinforcing bar 12S1 that produces the output waveform shown in FIG. 6 is the same as the cover thickness CT of the short reinforcing bar 12S1 that produces the output waveform shown in FIG.

6, the vertical axis corresponds to the output value of the eddy current sensor 51, and the horizontal axis corresponds to the distance in the X-axis direction from the end surface 11S of the concrete panel 11, as in the case of FIG. 6, the output value of the eddy current sensor 51 starts to increase at the position of the distance D1 from the end face 11S, and the output value of the eddy current sensor 51 forms the first peak P11 at the position of the distance D11 from the end face 11S. , the output value of the eddy current sensor 51 forms a dip DP1 at a position a distance D12 from the end surface 11S, the output value of the eddy current sensor 51 forms a second peak P12 at a position a distance D13 from the end surface 11S, and the output value of the eddy current sensor 51 forms a second peak P12. The output value of the eddy current sensor 51 returns to zero at a position of a distance D14 from .

As described above, when the eddy current sensor 51 passes over the portion of the concrete panel 11 in which the two adjacent short reinforcing bars 12S1 and 12S2 are embedded, the output waveform is as indicated by the dashed line in FIG. Instead of an output waveform containing two independent convex waveforms, a series of output waveforms containing two peaks P11 and P12 and one dip DP1 as indicated by the solid line in FIG. ). This is because the magnetic fields generated by the eddy currents generated in the two short reinforcing bars 12S1 and 12S2 affect each other. The multi-peak waveform may be a continuous output waveform including three or more peaks and two or more dips derived from three or more adjacent short reinforcing bars 12S in the concrete panel 11.

When the output waveform shown in FIG. 6 is obtained, the estimation unit 50A of the calculation device 50 determines that the short reinforcing bar 12S1 is buried at a position a distance D11 from the end surface 11S where the first peak P11 is formed. and derive the distance D11 as an estimated value of the cover thickness CT for the short reinforcing bar 12S1.

However, when the actual cover thickness CT of the short reinforcing bar 12S1 is measured by destructive inspection, it is confirmed that the measured value of the cover thickness CT is smaller than the estimated value of the cover thickness CT. Specifically, as shown in FIG. 7, which is an enlarged view of the range R1 surrounded by the dashed line in FIG. It is confirmed that only the distance GP is greater. Below, this distance GP is referred to as a deviation amount.

Therefore, the arithmetic device 50 is configured to correct the estimated value of the fogging thickness CT derived from the peaks of the output waveform when a multi-peak waveform as shown in FIG. 6 is detected.

A method of deriving a correction amount used by the calculation device 50 to correct the estimated value of the fogging thickness CT will be described below with reference to FIG. FIG. 8 is an enlarged view of the output waveform of the eddy current sensor 51. FIG. Specifically, FIG. 8 is an enlarged view of a portion including before and after the first peak P11 in the output waveform shown in FIG.

When the correction unit 50B of the arithmetic device 50 detects an output waveform including two peaks P11 and P12 and one dip DP1 as shown in FIG. A moving average line L10 is derived. In the example of FIG. 8 , the correcting unit 50B includes the preceding two output values and the following two output values among the output values of the eddy current sensor 51 repeatedly obtained in a predetermined control cycle. An average value of the two output values is derived as a moving average value corresponding to each output value of the eddy current sensor 51 . However, the number of preceding output values may be other than two, and the number of subsequent output values may be other than two. Also, the number of preceding output values may differ from the number of subsequent output values.

Then, the correction unit 50B derives the tangent angle, which is the angle between the tangent to each point forming the moving average line L10 and the horizontal axis. Specifically, the correction unit 50B determines the upward tangent angle α (absolute value), which is the tangent angle for each point between the point P21 and the point P22 on the moving average line L10, and the point on the moving average line L10. and the downward tangent angle β (absolute value), which is the tangent angle for each point between P22 and P23. The point P21 corresponds to the point P10 on the output waveform at which the output value of the eddy current sensor 51 starts to increase, the point P22 corresponds to the first peak P11 on the output waveform, and the point P23 corresponds to the output It corresponds to the dip DP1 on the waveform. In this case, the shape of the portion from the point P10 to the dip DP1 in the output waveform means the peak shape of the output waveform of the eddy current sensor 51.

Then, the correction unit 50B derives a point on the moving average line L10 at which the upward tangent angle α is maximum, and derives a point on the moving average line L10 at which the downward tangent angle β is maximum.

After that, the correction unit 50B calculates a slope ratio (αmax/βmax), which is the ratio of the maximum value αmax of the upward tangent angle α to the maximum value βmax of the downward tangent angle β. However, the slope ratio may be the ratio (βmax/αmax) of the maximum value βmax of the downward tangent angle β to the maximum value αmax of the upward tangent angle α.

In the example of FIG. 8, the correction unit 50B derives the upward tangent line angle α with respect to the point P31 on the moving average line L10 as the maximum value αmax, and derives the downward tangent line angle β with respect to the point P32 on the moving average line L10 with the maximum value βmax. derived as Then, the correction unit 50B acquires the tilt ratio (αmax/βmax).

After that, the correction unit 50B refers to a reference table that stores the correspondence relationship between the tilt ratio and the correction amount, which is stored in the nonvolatile storage device, and derives the correction amount corresponding to the acquired tilt ratio.

FIG. 9 is a scatter diagram showing an example of the correspondence relationship between the slope ratio and the correction amount. The vertical axis in FIG. 9 corresponds to the deviation amount, that is, the correction amount, and the horizontal axis corresponds to the tilt ratio. The deviation amount is the difference between the estimated value of the cover thickness CT and the actual cover thickness CT. A distance GP in FIG. 7 is an example of the amount of deviation.

The amount of deviation indicated by each point in FIG. 9 is based on actual measurements obtained by destructive testing of a plurality of concrete panels 11 in which the short reinforcing bars 12S1 and 12S2 are embedded. A line segment L20 in FIG. 9 indicates a regression line based on the method of least squares. The correction unit 50B refers to a reference table that stores the correspondence relationship between the tilt ratio and the correction amount represented by the regression line in FIG. 9, and derives the correction amount corresponding to the obtained tilt ratio. For example, when the value of the tilt ratio is "10", the correction unit 50B derives the value of the correction amount "-7 [mm]". The correction unit 50B may substitute the slope ratio into the regression equation for the regression line in FIG. 9 to calculate the correction amount. Alternatively, the correction unit 50B refers to a reference table that stores the correspondence represented by the approximate straight line derived by a method other than the least squares method, or adds the slope ratio to the calculation formula for such an approximate straight line. By substituting, a correction amount corresponding to the obtained tilt ratio may be derived.

Finally, the correcting unit 50B calculates a value obtained by adding the correction amount to the estimated value of the fog thickness CT estimated by the estimating unit 50A as a corrected estimated value of the fog thickness CT.

Next, with reference to FIG. 10, the flow of the process of estimating the cover thickness CT of the short reinforcing bars 12S1 embedded in the concrete panel 11 by the arithmetic device 50 (hereinafter referred to as "cover thickness estimation process") will be described. FIG. 10 shows a flowchart of an example of fogging thickness estimation processing. The computing device 50 executes this cover thickness estimation processing, for example, each time the eddy current sensor 51 finishes scanning the individual concrete panels 11 successively conveyed by the moving mechanism 52 . Note that the arithmetic device 50 continuously acquires the output value of the eddy current sensor 51 at a predetermined control cycle regardless of whether or not the fogging thickness estimation process is being executed. Based on the output value of the eddy current sensor 51 , the arithmetic device 50 is configured to detect the start and end of scanning of each concrete panel 11 by the eddy current sensor 51 . However, the computing device 50 may be configured to detect the start and end of scanning of each concrete panel 11 by the eddy current sensor 51 based on the output of another sensor such as a proximity sensor.

First, the arithmetic device 50 determines whether or not a peak has been detected in the output waveform of the eddy current sensor 51 (step ST1). In this embodiment, the computing device 50 detects that the output value of the eddy current sensor 51 for the most recently scanned concrete panel 11 exceeds a first predetermined value and then falls below a second predetermined value that is smaller than the first predetermined value. is detected, it is determined that a peak has been detected. However, the second predetermined value may be the same value as the first predetermined value. Alternatively, the computing device 50 may determine whether or not a peak has been detected using another method.

When determining that a peak has been detected (YES in step ST1), the estimating section 50A of the arithmetic device 50 estimates the fog thickness CT based on the position of the peak in the output waveform (step ST2). In the present embodiment, the estimating unit 50A detects a point on the ventral surface 11a of the concrete panel 11 immediately below the eddy current sensor 51 and the end surface 11S of the concrete panel 11 (see FIG. 1) when the computing device 50 detects a peak. is estimated as the cover thickness CT of the short reinforcing bar 12S1.

After that, the arithmetic device 50 determines whether or not a multi-peak waveform has been detected (step ST3). In this embodiment, as shown in FIG. 6, for example, the arithmetic unit 50 determines that the output value of the eddy current sensor 51 falls below a third predetermined value smaller than the second predetermined value after forming the first peak P11. When the second peak P12 is formed without any peaks, it is determined that a multi-peak waveform has been detected. Alternatively, the computing device 50 may use another method to determine whether a multi-peak waveform has been detected.

If it is determined that a multiple peak waveform has not been detected (NO in step ST3), the calculation device 50 causes the display device 53 to display the estimated value of the fog thickness CT estimated in step ST2 (step ST8). In the present embodiment, the calculation device 50 analyzes the output waveform as shown in FIG. 5, for example, and corrects the fogging thickness CT estimated in step ST2 when it is determined that a multiple peak waveform is not detected. Instead, the fog thickness CT estimated in step ST2 is displayed on the display device 53 as it is.

On the other hand, if it is determined that multiple peak waveforms have been detected (YES in step ST3), the correction section 50B of the arithmetic device 50 derives a moving average line (step ST4). In this embodiment, for example, when the correction unit 50B analyzes the output waveform as shown in FIG. 6 and determines that multiple peak waveforms are detected, it derives a moving average line as indicated by the dashed line in FIG.

After that, the correction unit 50B calculates the maximum value αmax of the upward tangent line angle α and the maximum value βmax of the downward tangent line angle β regarding the derived moving average line (step ST5). In the example shown in FIG. 8, the correction unit 50B converts the upward tangent line angle α with respect to the tangent line L11 passing through the point P31 on the moving average line corresponding to the waveform portion on the left side of the first peak P11 in the output waveform to the upward tangent line angle It is calculated as the maximum value αmax of α. Further, the correction unit 50B sets the downward tangent line angle β with respect to the tangent line L12 passing through the point P32 on the moving average line corresponding to the waveform portion on the right side of the first peak P11 in the output waveform to the maximum value βmax of the downward tangent line angle β. Calculate as Further, the correction unit 50B calculates a tilt ratio (αmax/βmax), which is the ratio of the maximum value αmax of the upward tangent angle α to the maximum value βmax of the downward tangent angle β.

After that, the correction unit 50B derives a correction amount based on the tilt ratio (αmax/βmax) (step ST6). In this embodiment, the correction unit 50B receives the derived tilt ratio as an input, and refers to a reference table that stores the relationship between the tilt ratio and the deviation amount (correction amount) represented by the regression line shown in FIG. A correction amount corresponding to the tilt ratio is derived.

After that, the correction unit 50B corrects the fogging thickness CT using the derived correction amount (step ST7). In the present embodiment, the correction unit 50B calculates a corrected estimated value by adding the correction amount to the estimated value of the fogging thickness CT estimated by the estimating unit 50A in step ST2. Note that the correction amount may be a positive value or a negative value.

After that, the arithmetic device 50 causes the display device 53 to display the corrected estimated value of the fogging thickness CT corrected in step ST7 (step ST8). In this embodiment, for example, when the calculation device 50 analyzes the output waveform as shown in FIG. The corrected estimated value of the fogging thickness CT corrected in step ST7 is displayed on the display device 53 .

When determining that no peak has been detected (NO in step ST1), the arithmetic device 50 displays a warning (step ST9). The computing device 50 causes, for example, the sound output device 54 to output a warning sound, and the display device 53 to display a text message such as "reinforcement cannot be detected." Note that the warning display may be accompanied by stopping the moving mechanism 52 or the like. Alternatively, the warning display may be replaced by the output of a warning sound or the output of a warning sound accompanied by the stoppage of the moving mechanism 52 or the like.

The calculation device 50 may be configured to display a warning when the estimated value or the corrected estimated value of the cover thickness displayed on the display device 53 deviates from a predetermined range.

As described above, the inspection apparatus 100 according to the embodiment of the present invention is an apparatus for inspecting a concrete panel 11 in which a metal such as a reinforcing bar 12 is embedded. A moving mechanism 52 for relatively moving the current sensor 51 and an arithmetic unit 50 are provided. Then, the arithmetic unit 50 estimates the position of the metal in the concrete panel 11 based on the peak position of the output waveform of the eddy current sensor 51, and estimates based on the peak shape of the output waveform of the eddy current sensor 51. It is configured to correct the position of the metal.

With this configuration, the computing device 50 can, for example, determine the cover of the short reinforcing bars 12S1 embedded in the concrete panel 11 as shown in FIG. Thickness CT can be estimated more accurately. Specifically, as shown in FIG. 6, for example, the computing device 50 estimates the cover thickness CT of the short reinforcing bar 12S1 based only on the position of the first peak P11 in the output waveform of the eddy current sensor 51. The cover thickness CT of the short reinforcing bar 12S1 can be estimated with high accuracy.

Note that the calculation device 50 can derive the cover thickness of the short reinforcing bar 12S2 in the same manner as in the case of deriving the cover thickness CT of the short reinforcing bar 12S1. The same applies to the short reinforcing bars 12S3 to 12S5.

In addition, the computing device 50 can derive the distance between the -X side end face of the concrete panel 11 and the short reinforcing bar 12S5 in the same manner as in the case of deriving the cover thickness CT of the short reinforcing bar 12S1.

Further, the computing device 50 may be configured to derive the cover thickness of the long reinforcing bar 12L in the same manner as in the case of deriving the cover thickness CT of the short reinforcing bar 12S1. The cover thickness of the long reinforcing bar 12L is, for example, the distance between the +Y side of the concrete panel 11 (see FIG. 1) and the long reinforcing bar 12L1, or the -Y side of the concrete panel 11 (see FIG. 1 ) and the long reinforcing bar 12L3. In this case, the eddy current sensor 51 is configured to be relatively movable in the Y-axis direction with respect to the concrete panel 11 . With this configuration, the inspection apparatus 100 can estimate the cover thickness based only on the position of the peak in the output waveform of the eddy current sensor 51 when the two long reinforcing bars 12L are buried next to each other. , the cover thickness of each of the two long reinforcing bars 12L can be estimated more accurately.

The computing device 50 may be configured to correct the estimated metal position based on, for example, the relationship between the left and right portions of the peak shape. Specifically, the correction unit 50B of the arithmetic device 50, as shown in FIG. The short reinforcing bar estimated by the estimating unit 50A based on the relationship between the maximum value αmax of the tangent angle α and the maximum value βmax of the downward tangent angle β with respect to the moving average line corresponding to the waveform portion on the right side of the first peak P11. It may be configured to correct the thickness of the 12S1 fog. More specifically, the correction unit 50B determines the short reinforcing bar estimated by the estimation unit 50A based on the slope ratio (αmax/βmax), which is the ratio of the maximum value αmax of the upward tangent angle α to the maximum value βmax of the downward tangent angle β. It may be configured to correct the thickness of the 12S1 fog.

That is, as shown in FIG. 8, the arithmetic device 50 derives the moving average line L10 of the output waveform of the eddy current sensor 51, and determines the upward tangent angle α of the portion on the left side of the point P22, which is the peak of the moving average line L10. The slope ratio, which is the ratio between the maximum value αmax and the maximum value βmax of the downward tangent angle β related to the portion on the right side of the point P22, is calculated, and the cover thickness of the short reinforcing bar 12S1 estimated by the estimation unit 50A based on the slope ratio may be configured to derive a correction amount when correcting the .

Then, the arithmetic unit 50 uses a formula representing the relationship between the tilt ratio and the correction amount as shown in FIG. may be used to derive the correction amount from the tilt ratio.

Preferred embodiments of the present invention have been described above. However, the invention is not limited to the embodiments described above. Various modifications or replacements may be applied to the above-described embodiments without departing from the scope of the present invention. Also, each of the features described with reference to the above-described embodiments may be combined as appropriate as long as they are not technically inconsistent.

For example, in the above embodiment, the correction section 50B is configured to derive a moving average line, but may be configured to smooth the output waveform using a low-pass filter or the like. In this case, the correction unit 50B may calculate the slope ratio based on the maximum value αmax of the upward tangent angle α and the maximum value βmax of the downward tangent angle β with respect to the smoothed output waveform.

Also, in the above-described embodiment, the corrector 50B is configured to derive the maximum value of the tangent angle, but instead of the maximum value, other statistical values such as a minimum value, an average value, or a median value are used. It may be configured to derive

Further, in the above-described embodiment, the correction unit 50B is configured to derive a tangent line, but instead of the tangent line, it is configured to derive another straight line such as a regression line or an approximate straight line based on the method of least squares. may be

Alternatively, the correction section 50B may be configured to recognize a waveform pattern of the output waveform of the eddy current sensor 51 and derive a correction amount corresponding to the recognized waveform pattern.

The inspection device 100 according to the embodiment of the present invention is used when checking whether or not the reinforcing bars 12 embedded in the concrete panel 11 are embedded according to manufacturing conditions.

DESCRIPTION OF SYMBOLS 11... Concrete panel 11S... End surface 12... Reinforcing bar 12L... Long reinforcing bar 12S... Short reinforcing bar 50... Arithmetic device 50A... Estimation part 50B... Correction part 51... Eddy current sensor 52 Moving mechanism 53 Display device 54 Sound output device

Claims (5)

An apparatus for inspecting concrete panels in which metal is embedded, comprising:
an eddy current sensor;
a movement mechanism for moving the eddy current sensor relative to the concrete panel;
a computing device;
The computing device is
estimating the position of the metal in the concrete panel based on the position of the peak of the output waveform of the eddy current sensor; and
configured to correct the estimated position of the metal based on the peak shape of the output waveform of the eddy current sensor,
Device. The computing device is configured to correct the estimated position of the metal based on the relationship between the left side portion and the right side portion of the peak shape.
A device according to claim 1 . The computing device is
Deriving a moving average line of the output waveform of the eddy current sensor,
Calculate a slope ratio, which is the ratio of the maximum upward tangent angle for the portion on the left side of the moving average peak and the maximum downward tangent angle for the portion on the right side of the moving average peak,
Based on the tilt ratio, it is configured to derive a correction amount when correcting the estimated position of the metal.
3. Apparatus according to claim 1 or 2. The calculation device uses a formula representing the relationship between the tilt ratio and the correction amount, or uses a reference table that stores the correspondence relationship between the tilt ratio and the correction amount, and calculates the correction amount from the tilt ratio. is configured to derive
4. Apparatus according to claim 3. A method for inspecting a concrete panel with embedded metal, comprising:
A computing device receives an output of an eddy current sensor that moves relative to the concrete panel,
The computing device estimates the position of the metal in the concrete panel based on the position of the peak of the output waveform of the eddy current sensor, and
The computing device corrects the estimated position of the metal based on the peak shape of the output waveform of the eddy current sensor.
Method.

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