Reinforcing steel detector and method for detecting reinforcing steel

Abstract

To provide a reinforcing steel detector and a method for detecting a reinforcing steel which improve the accuracy of detecting a reinforcing steel buried in a concrete structure.SOLUTION: A reinforcing steel detector 100 of the present invention includes: a collection unit 1 for collecting acceleration data from an acceleration sensor 30 attached to a boring machine 10 for boring a hole in a concrete 20; an analysis unit 2 for performing frequency analysis on the collected acceleration data; and a determination unit 3 for determining the presence of a reinforcing steel buried in the concrete 20 on the basis of the result of the frequency analysis. The reinforcing steel detector 100 further includes an extraction unit 4 for extracting the waveform of the frequency band resulting from boring a hole in concrete from the acceleration data in the frequency analysis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reinforcing bar detection device and a reinforcing bar detection method. [Background technology]

[0002] The Post-Head-Bar (PHB, registered trademark) method is known as a technique for improving the earthquake resistance of existing concrete structures (see, for example, Patent Document 1). The PHB method is a method for improving the shear strength of an existing concrete structure by drilling an insertion hole from the surface of the existing concrete structure with a drill or the like, inserting a shear reinforcement member into the insertion hole, and integrating it with the existing concrete structure. When drilling an insertion hole, it is preferable to grasp the position of the reinforcing bar embedded in the existing concrete structure. Methods for detecting reinforcing bars in an existing concrete structure include those that use a reinforcing bar arrangement diagram at the time of construction of the existing concrete structure and non-destructive testing. Examples of non-destructive testing include the inventions in Patent Documents 2 and 3. Patent Document 2 discloses a non-destructive testing method for reinforced concrete structures that uses an electromagnetic wave radar to measure the position directly above the reinforcing bar relative to the wall surface. Patent Document 3 discloses an invention for measuring the cover thickness of reinforcing bars in a reinforced concrete wall by combining an electromagnetic exploration method with a magnetic exploration method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4472729 [Patent Document 2] Patent Publication No. 2021-128029 [Patent Document 3] JP 2003-315004 A Summary of the Invention [Problem to be solved by the invention]

[0004] The inventions of Patent Documents 2 and 3 have a problem in that it is difficult to detect reinforcing bars buried deep inside a concrete structure. From this perspective, an object of the present invention is to provide a reinforcing bar detection device and a reinforcing bar detection method that improve the accuracy of detecting reinforcing bars buried in concrete structures. [Means for solving the problem]

[0005] The present invention, which solves the above-mentioned problems, is a rebar detection device that includes a collection unit that collects acceleration data from an acceleration sensor attached to a drilling machine that drills holes in a concrete structure, an analysis unit that performs frequency analysis on the collected acceleration data, and a determination unit that determines the presence of rebar buried in the concrete structure based on the results of the frequency analysis. The present invention also provides a rebar detection method comprising the steps of collecting acceleration data from an acceleration sensor attached to a drilling machine that drills holes in a concrete structure, performing frequency analysis on the collected acceleration data, and determining the presence of rebar buried in the concrete structure based on the results of the frequency analysis. According to the present invention, the spectrum during drilling of concrete can be observed according to the progress of drilling by frequency analysis of acceleration data. In addition, when the drill of the drilling machine comes into contact with reinforcing bars, a change in the spectrum intensity can be observed in a specific frequency band. Such a change in the spectrum intensity also applies to reinforcing bars buried deep inside a concrete structure. Therefore, reinforcing bars buried inside a concrete structure can be detected in real time.

[0006] In addition, it is preferable that the frequency analysis further comprises an extraction unit that extracts a waveform of a frequency band caused by drilling into concrete from the acceleration data. This allows the change in spectral intensity caused by the contact of the reinforcing bar to be observed more clearly.

[0007] In addition, it is preferable that the determination unit determines the possibility of the presence of reinforcing bars based on a change in an amplitude value of the extracted waveform. This makes it possible to detect the signs that the drill of the drilling machine is about to come into contact with the rebar, allowing the drilling operation to be adjusted.

[0008] It is also preferable that the collection unit collects distance data from a distance sensor attached to the drilling machine, the analysis unit calculates the drilling length or drilling speed from the collected distance data, and the determination unit determines the presence of the reinforcing bar based on the calculated drilling length or drilling speed. This allows the stationary value of the drilling length or the zero value of the drilling speed to be observed when the drill of the drilling machine comes into contact with the reinforcing bar. Such stationary or zero values ​​also apply to reinforcing bars buried deep inside a concrete structure. Therefore, reinforcing bars buried in a concrete structure can be detected in real time.

[0009] The present invention also provides a rebar detection device that includes a collection unit that collects distance data from a distance sensor attached to a drilling machine that drills holes in a concrete structure, an analysis unit that calculates the drilling length or drilling speed from the collected distance data, and a determination unit that determines the presence of rebar buried in the concrete structure based on the calculated drilling length or drilling speed. The present invention also provides a rebar detection method comprising the steps of collecting distance data from a distance sensor attached to a drilling machine that drills holes in a concrete structure, calculating a drilling length or a drilling speed from the collected distance data, and determining the presence of rebar buried in the concrete structure based on the calculated drilling length or drilling speed. According to the present invention, when the drill of the drilling machine comes into contact with the reinforcing bar, the steady-state value of the drilling length or the zero value of the drilling speed can be observed. Such steady-state value or zero value also applies to the reinforcing bar buried deep in the concrete structure. Therefore, the reinforcing bar buried in the concrete structure can be detected in real time. Effect of the Invention

[0010] According to the present invention, it is possible to improve the detection accuracy of reinforcing bars buried in concrete structures. [Brief description of the drawings]

[0011] [Figure 1] 1 is an overall view of a drilling system using the reinforcing bar detection device of this embodiment. [Diagram 2] 13 is a graph showing an example of the results of a frequency analysis of vibration during drilling. [Diagram 3] 1 is a graph showing an example of a raw waveform of acceleration data. [Figure 4] 1 is a graph showing an example of a waveform after passing through a BPF. [Diagram 5] 13 is a graph showing an example of the change over time in amplitude value from 500 Hz to 900 Hz. [Figure 6] 13 is a graph showing an example of change in hole length over time. [Figure 7] 13 is a graph showing an example of the change in drilling speed over time. [Figure 8] 13 is a graph showing an example of the change over time in the judgment value of drilling compressed gravel abutment. [Figure 9] 3 is a flowchart showing a reinforcing bar detection method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In each drawing, common or similar components are denoted by the same reference numerals, and duplicated explanations thereof will be omitted.

[0013] [composition] FIG. 1 is an overall view of a drilling system using the reinforcing bar detection device of this embodiment. This drilling system includes a drilling machine 10 and a reinforcing bar detection device 100, and analyzes the drilling of concrete 20 by the drilling machine 10. The drilling machine 10 is a device that drills a concrete structure. The drilling machine 10 is held by a jig (not shown) so as to be horizontally movable, and the drill 11 of the drilling machine 10 can drill holes horizontally in the existing concrete 20 at a predetermined drilling speed. An acceleration sensor 30 and a laser range finder 40 are attached to the drilling machine 10. The acceleration sensor 30 is a three-axis acceleration sensor that detects vibrations during drilling. The laser range finder 40 is a distance sensor that measures the distance between the drilling machine 10 and the concrete 20 by irradiating the concrete 20 with a laser and receiving the reflected light.

[0014] The reinforcing bar detection device 100 is a computer that detects reinforcing bars buried in concrete 20 during drilling. The reinforcing bar detection device 100 includes hardware such as an input unit, an output unit, a control unit, and a storage unit. For example, when the control unit is configured with a CPU (Central Processing Unit), information processing by a computer including the control unit is realized by program execution processing by the CPU. Also, the storage unit included in the computer stores various programs for realizing the functions of the computer according to instructions from the CPU. This realizes collaboration between software and hardware. The programs can be provided by recording them on a recording medium or via a network. The reinforcing bar detection device 100 is connected to a console (not shown) used by a user so as to be able to communicate with the console. The console can display the processing results of the reinforcing bar detection device 100 and input requests to the reinforcing bar detection device 100.

[0015] The rebar detection device 100 includes a collection unit 1, an analysis unit 2, a determination unit 3, and an extraction unit 4. The collection unit 1 collects acceleration data from an acceleration sensor 30. The acceleration data is acceleration time history data obtained by measuring vibrations during drilling. The collection unit 1 also collects distance data from a laser range finder 40. The distance data is displacement time history data obtained by measuring the distance between the drilling machine 10 and the concrete 20. The collection unit 1 can be implemented as a detector equipped with an amplifier. Note that, for example, the collection unit 1 can be implemented as hardware separate from the hardware of the rebar detection device 100, and can be connected to the collection unit 1 and the rebar detection device 100 (the analysis unit 2, the determination unit 3, and the extraction unit 4) so ​​as to be communicatively connected therebetween. The analysis unit 2 performs frequency analysis on the acceleration data collected by the acceleration sensor 30. The frequency analysis is, for example, but not limited to, power FFT (Fast Fourier Transform). Power FFT is an analysis method that processes the waveform of vibration caused by drilling as the intensity for each frequency. The analysis unit 2 also calculates the drilling length or drilling speed from the distance data collected by the laser distance meter 40. The determination unit 3 determines the presence of reinforcing bars embedded in the concrete 20 based on the results of the frequency analysis by the analysis unit 2. The determination unit 3 also determines the presence of the reinforcing bars based on the drilling length or drilling speed calculated by the analysis unit 2. The extraction unit 4 extracts a waveform of a predetermined frequency band from the acceleration data in the frequency analysis. The predetermined frequency band is preferably a frequency band including characteristic frequency components contained in the acceleration data during drilling of a concrete hole. The extraction unit 4 can be, for example, a BPF (Band-Pass Filter), but is not limited thereto. The BPF can be, for example, a digital IIR (Infinite Impulse Response) filter, but is not limited thereto. In this embodiment, the model of the drilling machine 10, the mounting position of the acceleration sensor 30, the mounting position of the laser rangefinder 40, the drilling diameter, the diameter of the reinforcing bar embedded in the existing concrete 20, and the degree of contact (hammering, rubbing) between the drill 11 of the drilling machine 10 and the reinforcing bar can be changed as appropriate.

[0016] (Visualization of acceleration data) FIG. 2 is a graph showing an example of the results of frequency analysis of vibration during drilling. In FIG. 2, the vertical axis indicates the drilling length (or drilling time) and the horizontal axis indicates the spectrum frequency (sometimes simply called frequency), and the intensity of the drilling vibration waveform is shown in a heat map. The sampling frequency for collecting acceleration data by the collection unit 1 is 20 KHz, and data sampling is performed at 0.2 sec intervals. During drilling, the intensity is obtained in 10 Hz units in the frequency band of 0 to 10 KHz. The drilling vibration analysis direction coincides with the drilling direction of the drilling machine 10. FIG. 2 shows that a characteristic spectrum contained in the acceleration data during concrete drilling can be observed in the frequency band of 500 to 900 Hz (see the dashed-dotted ellipse in FIG. 2). 2, when the drill 11 of the drilling machine 10 comes into contact with a reinforcing bar embedded in the concrete 20, absorption of the spectrum from 500 to 900 Hz (a phenomenon in which the spectrum intensity of the frequency components included in the acceleration data decreases at 500 to 900 Hz) can be observed (see the dashed ellipse in FIG. 2). The determination unit 3 can determine the presence of a reinforcing bar based on such absorption of the spectrum.

[0017] (Determined by BPF) Considering the results of FIG. 2, it is preferable to pay attention to the vibration characteristics in the frequency band of 500 to 900 Hz. Therefore, the BPF as the extraction unit 4 is used to remove unnecessary components from the collected acceleration data. FIG. 3 is a graph showing an example of the raw waveform of the acceleration data. FIG. 4 is a graph showing an example of the waveform after passing through the BPF. As shown in FIG. 3, the waveform collected from the acceleration sensor 30 over a predetermined measurement period (for example, 0.1 sec) is a waveform in which many sine waves of various frequencies overlap. The waveform of about 130 (G) shown in FIG. 3 (part surrounded by a dashed circle) is a waveform caused by the impact force of the drilling machine 10, and the frequency band is 30 to 40 Hz. The extraction unit 4 performs BPF processing on the acceleration data of FIG. 3, thereby extracting a waveform in which many sine waves of frequencies included in the band of 500 to 900 Hz overlap, and the waveform shown in FIG. 4 is output. By passing through the BPF, the amount of information of the entire waveform can be reduced while retaining the characteristics of the acceleration data obtained during concrete drilling, thereby reducing the calculation load.

[0018] FIG. 5 is a graph showing an example of the change over time of the amplitude value of 500 Hz-900 Hz. The graph in FIG. 5 corresponds to a graph obtained by converting the waveform in FIG. 4 into an absolute value, calculating the average value of the absolute amplitude value over a predetermined measurement period (for example, 0.1 sec), and plotting the calculated average value at each interval (0.2 sec) of data sampling for drilling. Thus, the vertical axis of the graph in FIG. 5 indicates the average value (G) of the absolute value of acceleration (G), and the horizontal axis indicates the drilling time (Time (sec)). From FIG. 5, it can be seen that the average value indicates a predetermined value (4 to 7 (G)) during drilling of concrete, but suddenly drops to approximately 0 (G) around 150 (sec). From the sudden drop in the average value, the determination unit 3 can determine that the drill 11 of the drilling machine 10 has come into contact with the reinforcing bar about 150 (sec) after the start of drilling (the reinforcing bar is buried at a position about 150 (sec) after the start of drilling). For example, the judgment unit 3 can control the drilling machine 10 to stop drilling.

[0019] (Visualization of distance data) 6 is a graph showing an example of the change in the drilling length over time. As the drilling time (Time (sec)) elapses, the distance length L between the drilling machine 10 and the concrete 20, which is shown by the distance data, i becomes smaller (i indicates the order of sampling). The initial distance L0 of the hole drilling is measured in advance. The analysis unit 2 calculates the hole drilling length L (mm) as L = L0 - L i The graph in FIG. 6 corresponds to a plot of the hole-drilling length L at each interval (0.2 sec) of data sampling for hole-drilling. FIG. 6 shows that the hole-drilling length is stagnating. The determination unit 3 can determine that the drill 11 of the drilling machine 10 has come into contact with a reinforcing bar based on the stagnation of the hole-drilling length. For example, the determination unit 3 can control the drilling machine 10 to stop drilling.

[0020] (Determined by drilling speed) Since the drilling length calculated by the analysis unit 2 changes due to drilling vibrations, etc., even if the instantaneous value of the drilling length is calculated, there is a limit to the accuracy of judging whether or not the rebar is contacted. Therefore, the analysis unit 2 performs a moving average process on the distance data. Specifically, the analysis unit 2 first calculates the distance length L at the current sampling time. i and the distance length L at the previous sampling i-1 Difference S i , S i = L i - L i-1 Next, the analysis unit 2 calculates the calculated difference S i For example, calculate the moving average value for 4 seconds (20 data points). The calculated moving average value indicates the drilling length per unit time (mm / sec), that is, the drilling speed.

[0021] FIG. 7 is a graph showing an example of the change in drilling speed over time. The graph in FIG. 7 corresponds to a plot of the moving average value calculated as described above (in FIG. 7, shown as difference (mm / sec)) at each interval (0.2 sec) of the data sampling of the drilling. FIG. 7 confirms that the drilling progressed at an average drilling speed of 0.5 mm / sec, and then changed to approximately 0 mm / sec. When the average drilling speed has changed to 0 mm / sec, the determination unit 3 can determine that the drill 11 of the drilling machine 10 has come into contact with a rebar. For example, the determination unit 3 can control the drilling machine 10 to stop drilling.

[0022] (Sign of rebar contact) According to the graph of FIG. 5, before the amplitude value, i.e., the average value of the absolute value of the acceleration (G) suddenly drops about 150 (sec) from the start of drilling, an increase in the amplitude value can be confirmed for a period of 125 (sec) to 150 (sec) from the start of drilling. Also, according to the graph of FIG. 6, the stagnation of the drilling length is divided into a first stagnation for a period of 125 (sec) to 150 (sec) from the start of drilling, and a second stagnation after 150 (sec), and a phenomenon in which there is a slight step between the first and second stagnation can be confirmed. The reason why such a phenomenon can be confirmed is presumed to be as follows. That is, just before the drill 11 of the drilling machine 10 abuts against the reinforcing bar, the crushed concrete debris is in a state of being squeezed by the drilling machine 10. Due to this state, the amplitude value increased for a period of 125 (sec) to 150 (sec) from the start of drilling. After that, the compressed debris was broken and discharged outside the hole, and 150 seconds after the start of drilling, the drill 11 of the drilling machine 10 abutted against the rebar, causing a sudden drop in the amplitude value. In the graph of Fig. 6, the first stagnation indicates the state during the crushing of the debris, the step between the first and second stagnation indicates that the drilling has progressed slightly as the compressed debris is broken, and the second stagnation indicates the abutment against the rebar.

[0023] The analysis unit 2 can perform BPF processing to make the above phenomenon apparent. For example, the analysis unit 2 squares the amplitude values ​​shown in the graph of FIG. 5 to emphasize them, and then calculates a moving average value of 15 times (1.5 seconds) to smooth them. On the other hand, for comparison, the analysis unit 2 squares the amplitude values ​​shown in the graph of FIG. 5 to emphasize them, and then calculates a moving average value of 50 times (10 seconds). Note that the emphasis of the amplitude values ​​is not limited to squaring, and exponentialization other than squaring may also be used as long as the change in the graph is emphasized. Also, the emphasis of the amplitude values ​​is not essential. The analysis unit 2 calculates the judgment value of the following formula 1, for example, using two types of moving average values. Judgment value = (15-times moving average value - 50-times moving average value 10 seconds ago) / 50-times moving average value 10 seconds ago ...Formula 1

[0024] FIG. 8 is a graph showing an example of the change over time in the judgment value of the contact of drilled compressed rubble. The graph in FIG. 8 corresponds to the judgment value of Equation 1 from the graph in FIG. 5 plotted at intervals (0.2 sec) of the data sampling of drilling. Thus, the vertical axis of the graph in FIG. 8 indicates the judgment value, and the horizontal axis indicates the drilling time (Time (sec)). According to FIG. 8, the judgment value indicates a positive value of about 0 to 0.5 over a period of 125 (sec) to 150 (sec) from the start of drilling. When the judgment value indicates a threshold value (e.g., 0.5) or more, the judgment unit 3 can judge that the drill 11 of the drilling machine 10 has contacted the drilled compressed rubble over a period of 125 (sec) to 150 (sec) from the start of drilling. After that, when the judgment value becomes a negative value (e.g., about -1), the judgment unit 3 can judge that the drill 11 has contacted the reinforcing bar (the reinforcing bar is buried at a position 150 (sec) after the start of drilling). For example, the judgment unit 3 can detect contact with compressed gravel during drilling as a precursor to contact with a reinforcing bar, and control the drilling machine 10 to stop drilling before contact with the reinforcing bar.

[0025] [process] The process of the reinforcing bar detection device 100 will be described. FIG. 9 is a flowchart showing the reinforcing bar detection method of this embodiment. This process is repeatedly executed during drilling. First, the collection unit 1 collects acceleration data from the acceleration sensor 30 (step S1). Next, the analysis unit 2 performs power FFT processing on the collected acceleration data (step S2). Specifically, the analysis unit 2 creates the graph of FIG. 2. Next, the extraction unit 4 performs BPF processing on the acceleration data (step S3). Specifically, the extraction unit 4 extracts a waveform consisting of a frequency band of 500 to 900 Hz from the acceleration data. The analysis unit 2 creates the graph of FIG. 5. Note that the power FFT processing (step S2) or the BPF processing (step S3) may be selectively executed.

[0026] On the other hand, the collecting unit 1 collects distance data from the laser distance meter 40 (step S5). Next, the analyzing unit 2 performs calculation processing on the collected distance data (step S6). Specifically, the analyzing unit 2 calculates the hole drilling length to create the graph of FIG. 6, or calculates the hole drilling speed to create the graph of FIG. 7. After at least one of steps S2, S3, and S6, the determining unit 3 performs reinforcing bar determination processing (step S7). Specifically, in the result of the power FFT processing (step S2), it is determined whether or not there is absorption of the spectrum. If there is absorption, the determining unit 3 can determine the presence of reinforcing bar. Also, in the result of the BPF processing (step S3), if the amplitude value becomes 0 (G), the determining unit 3 can determine the presence of reinforcing bar. Also, in the result of the calculation processing (step S6), if the increase in the hole drilling length stagnates or the hole drilling speed changes to 0 mm / sec, the determining unit 3 can determine the presence of reinforcing bar. Furthermore, if the result of the BPF process (step S3) shows an increase in the amplitude value or a judgment value (see FIG. 8) that exceeds a threshold, the judgment unit 3 can judge that this is a precursor to rebar contact.

[0027] [effect] According to this embodiment, the spectrum during drilling of concrete can be observed according to the progress of drilling by frequency analysis of acceleration data. In addition, when the drill 11 of the drilling machine 10 abuts against a reinforcing bar, a change in the spectrum intensity can be observed in a specific frequency band. Such a change in the spectrum intensity also applies to reinforcing bars buried deep in the concrete 20. Therefore, reinforcing bars buried in the concrete 20 can be detected in real time. Furthermore, according to this embodiment, when the drill 11 of the drilling machine 10 comes into contact with a reinforcing bar, a steady-state value of the hole-drilling length or a zero value of the hole-drilling speed can be observed. Such steady-state value or zero value also applies to reinforcing bars buried deep in the concrete 20. Therefore, reinforcing bars buried in the concrete 20 can be detected in real time. As a result, the detection accuracy of reinforcing bars buried in the concrete 20 can be improved. Moreover, the extraction unit 4 allows the change in the spectrum intensity caused by the contact of the reinforcing bar to be observed more clearly. In addition, it is possible to detect the signs that the drill 11 of the drilling machine 10 is about to come into contact with the reinforcing bar, and the drilling operation can be adjusted.

[0028] [Variations] (a): The present invention is not limited to application to existing concrete structures, but can also be applied to structures made of other materials. (b): By using the same material for the drill 11 of the drilling machine 10 as the material buried in the existing concrete structure, the absorption of the spectrum can be observed in the power FFT processing of the acceleration data. Therefore, the presence of the material buried in the existing concrete structure can be determined during drilling. (c) The acceleration sensor 30 is not limited to a three-axis acceleration sensor, but may be a one-axis acceleration sensor or a two-axis acceleration sensor. (d): In this embodiment, the drilling machine 10 moves horizontally to drill holes in the existing concrete, but this is not limited to horizontal movement and horizontal drilling. For example, the drilling machine 10 may move vertically to drill holes vertically, or move diagonally to drill holes diagonally.

[0029] (e) It is also possible to realize a technology that appropriately combines the various technologies described in this embodiment. (f): The software described in this embodiment can be realized as hardware, and the hardware can be realized as software. (g) In addition, the hardware, software, flow charts, etc. may be modified as appropriate without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0030] 100 Reinforcement bar detector 1 Collection Department 2 Analysis section 3 Judgment section 4 Extraction part 10 Drilling Machine 11 Drill 20. Concrete 30 Acceleration Sensor 40 Laser range finder (distance sensor)

Claims

1. A collection unit that collects acceleration data from an acceleration sensor attached to a drilling machine that drills a concrete structure; an analysis unit that performs frequency analysis on the collected acceleration data; A reinforcing bar detection device comprising: a determination unit that determines the presence of reinforcing bars buried in the concrete structure based on the results of the frequency analysis.

2. The reinforcing bar detection device according to claim 1 , further comprising an extraction unit that extracts, in the frequency analysis, a waveform in a frequency band caused by drilling into concrete from the acceleration data.

3. The reinforcing bar detection device according to claim 2 , wherein the determination unit determines the possibility of the presence of the reinforcing bar based on an increase in an amplitude value of the extracted waveform.

4. The collection unit collects distance data from a distance sensor attached to the drilling machine, The analysis unit calculates a drilling length or a drilling speed from the collected distance data, The reinforcing bar detection device according to claim 1 , wherein the determination unit determines the presence of the reinforcing bar based on the calculated hole drilling length or hole drilling speed.

5. A collection unit that collects distance data from a distance sensor attached to a drilling machine that drills a concrete structure; An analysis unit that calculates a drilling length or a drilling speed from the collected distance data; A reinforcing bar detection device comprising: a judgment unit that judges the presence of reinforcing bars buried in the concrete structure based on the calculated drilling length or drilling speed.

6. Collecting acceleration data from an acceleration sensor attached to a drilling machine that drills a concrete structure; performing a frequency analysis on the collected acceleration data; and determining the presence of reinforcing bars buried in the concrete structure based on the results of the frequency analysis.

7. Collecting distance data from a distance sensor attached to a drilling machine that drills a concrete structure; calculating a drilling length or a drilling speed from the collected distance data; and determining the presence of reinforcing bars buried in the concrete structure based on the calculated drilling length or drilling speed.

Images