Underground radar device and buried object survey method therefor

Abstract

To provide an underground radar device and a buried object survey method therefor capable of estimating the reliability of the relative permittivity used for calculating the depth of a buried object, and issuing a warning about poor depth accuracy to a user when the reliability of the relative permittivity is estimated to be low.SOLUTION: An underground radar device comprises a radar unit 21, an underground survey device 22, and a display device 14, radiates an electromagnetic wave EM from a transmitting antenna 23 into the ground, receives a reflected wave RW reflected at a boundary surface between materials having different relative permittivities by means of a receiving antenna 24, and surveys a buried object BO in the ground. A reliability calculation section 29 estimates the reliability of the relative permittivity used for calculating the depth of the buried object on the basis of changes in the road surface condition and the measurement speed of the measurement path. When the reliability is estimated to be low, a display section 14a issues a warning about poor depth accuracy to a user.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an underground radar device and buried object exploration method that radiates electromagnetic waves into the ground and measures the reflected waves to explore buried objects and internal structures. [Background technology]

[0002] One known "underground object detection device" for detecting buried pipes and the like buried underground is one that has a fixed transmitting antenna that transmits radio waves, while a moving receiving antenna is positioned directly above the buried pipe and calculates the relative dielectric constant of the soil and the burial depth of the buried pipe by examining the change in the propagation time of the reflected wave according to the moving distance of the receiving antenna (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-286983 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology disclosed in the above-mentioned Patent Document 1 determines the relative dielectric constant and burial depth on the premise that the approximate buried location of the buried pipe, the state of the soil (for example, that the relative dielectric constant in the soil is constant), etc. are known in advance. Furthermore, to determine the relative dielectric constant, it is necessary to move the receiving antenna in the direction in which the buried pipe is laid, which makes it necessary to have a buried pipe at a constant depth as a reference.

[0005] Therefore, in places where buried pipes are not buried to a certain depth, the reliability of the estimated relative permittivity is greatly impaired. Also, the estimated relative permittivity may vary significantly depending on the exploration conditions, such as the exploration speed and linearity of the probe, and the water content of the underground exploration area. Currently, the reliability of the estimated relative permittivity is determined by the experience and intuition of the user who measures it.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide an underground radar device and a buried object exploration method that estimate the reliability of the relative dielectric constant used to calculate the depth of a buried object, and warn the user of poor depth accuracy when the reliability of the relative dielectric constant is estimated to be low. [Means for solving the problem]

[0007] An underground radar device and buried object exploration method according to one embodiment of the present invention is a device and method that emits electromagnetic waves into the ground and receives reflected waves reflected at the boundary surface of materials with different dielectric constants to explore buried objects underground, and is characterized in that the reliability of the dielectric constant used to calculate the depth of the buried object is estimated based on the road surface condition of the measurement route and changes in the measurement speed, and when the reliability of the dielectric constant is estimated to be low, a warning is given to the user of poor depth accuracy. [Effects of the Invention]

[0008] According to the underground radar device and buried object exploration method of the present invention, the reliability of the relative dielectric constant of the buried medium used to calculate the depth of the buried object is estimated based on the road surface condition of the measurement route and changes in the measurement speed, and if the reliability of the relative dielectric constant is estimated to be low, the user is warned of poor depth accuracy. This allows the reliability of the dielectric constant used to calculate the depth of a buried object to be quantitatively estimated, and if the reliability of the dielectric constant is estimated to be low, a warning can be given to the user about poor depth accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view showing a schematic configuration of an underground radar device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram of the underground radar device shown in FIG. 1. [Figure 3] 3 is a flowchart showing a buried object exploration method in the underground radar device shown in FIGS. 1 and 2. [Figure 4] 4 is a flowchart illustrating the buried object detection method following FIG. 3. [Figure 5] 1 is a display image diagram of the exploration data in the buried object exploration method of the present invention. FIG. [Figure 6] 10 is a display image diagram of the exploration data after analysis processing in the buried object exploration method of the present invention. FIG. [Figure 7] FIG. 10 is an image diagram showing an example of an image displayed under normal conditions. [Figure 8] FIG. 10 is a diagram illustrating a display image in which blurring occurs at the edges of an image. [Figure 9] FIG. 10 is a diagram illustrating a display image when distortion occurs at the edge of an image. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a schematic configuration of an underground radar device according to an embodiment of the present invention. This underground radar device 10 moves in the direction of the arrow while emitting pulsed electromagnetic waves EM into the ground, and detects buried objects BO by receiving reflected waves RW reflected at the boundary surface between materials with different dielectric constants. A handle 13 is attached to a mobile body 12 having wheels 11 and a drive mechanism (not shown) for these wheels 11. A ground-photographing camera 15, an acceleration sensor 16, a gyro sensor 17, and an inclination sensor 18 are mounted on the mobile body 12.

[0011] The mobile body 12 also has a built-in underground exploration device and a radar unit, and a display device 14 that displays the exploration results is attached near the handle 13a of the handle 13. The user (operator) moves the mobile body 12 along the measurement route while holding the handle 13a and walking, and by thoroughly scanning the survey area, the exact location of the buried object BO is determined.

[0012] Figure 2 shows a block diagram of the underground radar device 10 shown in Figure 1. The underground radar device 10 includes a radar unit 21, an underground exploration device 22, and a display device 14. The radar unit 21 is provided with a transmitting antenna 23 and a receiving antenna 24. Pulsed electromagnetic waves EM generated by a transmitter (not shown) are emitted into the ground from the transmitting antenna 23, and are received and measured by the receiving antenna 24 while the radar unit 21 (underground radar device 10) is moved, thereby changing the relative distance between the transmitting and receiving antennas 23, 24 and the target, and capturing the shape of the target in the radar waveform.

[0013] The underground exploration device 22 is composed of a data acquisition unit 25, a signal processing unit 26, an analysis unit 27, an image analysis unit 28, a reliability calculation unit (reliability calculation means) 29, a ground photographing camera 15, an acceleration sensor 16, a gyro sensor 17, and an inclination sensor 18. When a reflected wave RW reflected at a boundary surface between materials with different relative dielectric constants in the soil is received by the receiving antenna 24, it is input to the data acquisition unit 25. The data acquired by the data acquisition unit 25 is input to the signal processing unit 26 where it is processed, and then input to the analysis unit 27 where it is analyzed.

[0014] Meanwhile, the ground photographing camera 15 is used to detect puddles on the ground along the measurement route, and the output of this camera 15 is input to the image analysis unit 28 to detect the presence or absence of puddles. The acceleration sensor 16 measures the maximum speed change during measurement, and the gyro sensor 17 measures the maximum angular velocity of the measurement route. Furthermore, the tilt sensor 18 measures the tilt of the measurement route.

[0015] The outputs of the image analysis unit 28, acceleration sensor 16, gyro sensor 17, and tilt sensor 18 are each input to a reliability calculation unit 29. The reliability calculation unit 29 uses the presence or absence of puddles on the ground of the measurement route, the inclination of the measurement route, and the maximum angular velocity as parameters for information on the road surface condition of the measurement route, and the change in maximum velocity during measurement as a parameter for information on change in measurement velocity, to estimate the reliability of the relative dielectric constant. The reliability calculated by the reliability calculation unit 29 is then input to the analysis unit 27, and the analysis results by the analysis unit 27 and the reliability information calculated by the reliability calculation unit 29 are displayed on the display device 14.

[0016] 3 and 4 are flowcharts showing a buried object exploration method in the underground radar device 10 shown in Fig. 1 and Fig. 2. When the underground exploration process is started (step ST1), the underground radar device 10 (mobile body 12) moves while emitting pulsed electromagnetic waves EM into the ground from the transmitting antenna 23, and the reflected waves RW reflected at the boundary surface between materials with different relative dielectric constants are received by the receiving antenna 24, and the data acquisition unit 25 acquires exploration data (step ST2). The data acquired by the data acquisition unit 25 is input to the signal processing unit 26, where signal processing is performed (step ST3). The signal-processed exploration data is displayed on the display unit 14a of the display device 14 (step ST4).

[0017] 5 is a display image diagram of the exploration data in the buried object exploration method of the present invention. Here, the vertical axis represents depth (meters), the horizontal axis represents travel distance (meters), and the mobile body 12 of the underground radar device 10 moves from left to right in the diagram. This image is displayed on the display unit 14a in step ST4, and shows the raw exploration data before data analysis processing in real time.

[0018] In the next step ST5, it is determined whether or not the exploration has ended. If it is determined that the exploration has ended (if step ST5 is Yes), the underground exploration process ends (step ST6), and the analysis unit 27 executes an analysis process of the exploration data (step ST7). On the other hand, if it is determined that the exploration has not ended (if step ST5 is No), the process returns to step ST2 and the exploration data is acquired. Then, the operations of steps ST2 to ST5 are repeated until it is determined that the exploration has ended.

[0019] Figure 6 is a display image of the exploration data after analysis processing in the buried object exploration method of the present invention. Here, too, the vertical axis is depth (meters) and the horizontal axis is travel distance (meters). The two rectangular areas represent buried objects BO, and what appears to be a buried pipe (labeled "N2-1 S0.94") was detected at a depth of approximately 0.4 m, about 4.0 m from the measurement start point, and what appears to be a buried pipe (labeled "N3-1 S1.00") was detected at a depth of approximately 1.5 m, about 5.5 m from the measurement start point.

[0020] Next, it is determined whether or not a buried object BO exists (step ST8), and if it is determined that a buried object BO exists (if step ST8 is Yes), the analysis unit 27 executes a process of estimating the relative dielectric constant (step ST9). Also, the image taken by the ground photographing camera 15 is input to the image analysis unit 28, and an image analysis process is performed during the exploration (step ST10), and the reliability calculation unit 29 determines whether or not there is a puddle on the ground above the buried object BO based on the image analysis result (step ST11).

[0021] Furthermore, the reliability calculation unit 29 calculates the degree of change in inclination based on the inclination angle in the pitch direction of the mobile body 12 detected by the inclination sensor 18 (step ST12).The reliability calculation unit 29 calculates the maximum angular velocity during exploration based on the angular velocity detected by the gyro sensor 17 (step ST13).The reliability calculation unit 29 calculates the maximum velocity during exploration based on the acceleration detected by the acceleration sensor 16 (step ST14). If it is determined in step ST8 that no buried object BO is present (if step ST8 is No), the processing from step ST9 onwards is unnecessary and is therefore terminated.

[0022] Next, based on the calculation results of steps ST11 to ST14, the reliability calculation unit 29 calculates the reliability of the relative dielectric constant (step ST15), and inputs the calculation results to the analysis unit 27. The reliability calculation unit 29 calculates the reliability of the relative dielectric constant as follows. The reliability of the relative dielectric constant is R, the presence or absence of puddles on the ground above the buried object BO is A, the maximum speed during the survey is B, the degree of change in slope is C, and the maximum angular velocity during the survey is D. The weights of these parameters A, B, C, and D are respectively W A , W B , W C , W D Then, the reliability is estimated based on the following equation:

number

[0023] Next, a calculation example is shown. Weight W A =100, W B =100, W C =400, W D When =400, When A=1 (no puddles), B=1 (below the exploration limit speed), C=0.5 (minimum inclination 0.5°, maximum 3.5°), and D=0.7 (maximum angular velocity 0.3), the equation is as follows:

number

[0024] On the other hand, the same weight WA =100, W B =100, W C =400, W D When =400, When A=0 (puddle present), B=1 (below the limit speed for exploration), C=0.1 (minimum inclination 0.5°, maximum 5°), and D=0.8 (maximum angular velocity 0.2), the equation is as follows:

number

[0025] The analysis unit 27 determines whether the reliability is equal to or greater than a predetermined threshold value based on the dielectric constant estimated in step ST9 and the reliability of the dielectric constant calculated in step ST15 (step ST16). This threshold value differs depending on the survey area and the required accuracy, and can be set by the user.

[0026] If the reliability is equal to or greater than a predetermined threshold (if step ST16 is Yes), the display unit 14a displays the relative dielectric constant and the depth of the buried object B0 (step ST17). On the other hand, if the reliability is less than the predetermined threshold (if step ST16 is No), the display unit 14a displays a warning that the accuracy of the depth of the buried object B0 is poor (step ST18). The user who received the warning can improve the reliability by re-measuring the same measurement path or by changing the direction of the measurement path.

[0027] Fig. 7 shows an example of a normal image (high depth accuracy) displayed in step ST17. Fig. 8 shows a display image when blurring occurs at the edge of the image, and Fig. 9 shows a display image when distortion occurs at the edge of the image.

[0028] When the depth accuracy is high, the edge caused by the buried object BO appears clearly as an arc, as shown by the box in Figure 7. In contrast, when there is a puddle on the ground along the measurement path, the edge itself becomes blurred (faint) or is not displayed, as shown by the box in the corresponding position in Figure 8. Furthermore, if there are differences in the tilt, angular velocity, and maximum velocity, the arc edge will be distorted as shown in FIG. 9 (the right part indicated by the arrow in the area enclosed by the square).

[0029] Therefore, if the reliability is not above a predetermined threshold, the display unit 14a will display a blurred or distorted edge as shown in Figure 8 or Figure 9, and will also display a warning that the depth accuracy of the buried object BO is inaccurate or poor.

[0030] As described above, according to the present invention, the reliability of the dielectric constant of the buried medium used to calculate the depth of a buried object B0 is estimated based on the road surface condition of the measurement path and changes in the measurement speed, and when it is estimated that the reliability of the dielectric constant is low, a warning of poor depth accuracy is given to the user. This makes it possible to quantitatively estimate the reliability of the dielectric constant used to calculate the depth of a buried object B0, and when it is estimated that the reliability of the dielectric constant is low, a warning of poor depth accuracy is given to the user. Then, the user who receives the warning can measure the same measurement route again, or measure again by changing the direction of the measurement route, thereby improving reliability.

[0031] The configurations and operation procedures described in the above embodiments are merely schematic illustrations to enable understanding and implementation of the present invention. Therefore, the present invention is not limited to the described embodiments, and can be modified in various forms without departing from the scope of the technical idea set forth in the claims.

[0032] For example, the monitor screen of a personal computer can be used as the display device 14 that displays the exploration results, and the data acquisition unit 25, signal processing unit 26, analysis unit 27, and image analysis unit 28 of the underground exploration device 22 may be configured to be realized by software on the personal computer.

[0033] Furthermore, although the case where the acceleration sensor 16 is used to measure the change in maximum speed during measurement has been described, other sensors that measure the rotation speed of the wheels 11 or the moving speed of the mobile body 12 can also be used.

[0034] Furthermore, the display device 14 (display unit 14a) that displays reliability information has been used as an example of a notification means for warning the user of poor depth accuracy, but a light-emitting device that emits a light alarm or a sound-emitting device that emits an alarm sound may also be used, and multiple devices may be combined, such as a display and an alarm sound, a display and a light alarm (flashing of the display screen), or an alarm sound and a light alarm. [Explanation of symbols]

[0035] 10...underground radar device, 11...wheel, 12...mobile body, 13...handle, 14...display device, 14a...display unit (alert means), 15...ground photographing camera, 16...acceleration sensor, 17...gyro sensor, 18...tilt sensor, 21...radar unit, 22...underground exploration device, 23...transmitting antenna, 24...receiving antenna, 25...data acquisition unit, 26...signal processing unit, 27...analysis unit, 28...image analysis unit, 29...reliability calculation unit (reliability calculation means), EM...electromagnetic wave, RW...reflected wave, BO...buried object

Claims

1. A device for detecting buried objects underground by emitting electromagnetic waves into the ground and receiving the waves reflected at the boundary surface between materials with different dielectric constants, a reliability calculation means for estimating the reliability of the relative dielectric constant used to calculate the depth of the buried object based on the road surface condition of the measurement route and changes in the measurement speed; a notification means for warning a user of poor depth accuracy when the reliability calculation means estimates that the reliability is low; A ground penetrating radar device comprising:

2. 2. The underground radar device according to claim 1, wherein the reliability calculation means uses, as parameters for information on the road surface condition of the measurement path, the presence or absence of puddles on the ground of the measurement path, and the inclination and maximum angular velocity of the measurement path, and uses, as parameters for information on the change in the measurement velocity, a change in maximum velocity during measurement, to estimate the reliability of the relative dielectric constant.

3. 3. The underground radar device according to claim 2, further comprising: a camera that detects puddles on the ground of the measurement path; an inclination sensor that measures the inclination of the measurement path; a gyro sensor that measures the maximum angular velocity of the measurement path; and an acceleration sensor that measures changes in maximum velocity during measurement.

4. The reliability calculation means defines the reliability of the relative dielectric constant as R, the presence or absence of a puddle on the buried object as A, the maximum speed during the search as B, the degree of change in the slope as C, and the maximum angular speed during the search as D, and assigns weights to the parameters A, B, C, and D as W. Ａ , W Ｂ , W Ｃ , W Ｄ Then, the reliability is estimated based on the following formula: [Equation 1] However, when there is a puddle on the buried object, A=0, and when there is no puddle, A=1. When the search limit speed is exceeded, B=0, and when it is not exceeded, B=1. The degree of change in the slope is expressed as "C = minimum value (degrees) / maximum value (degrees)" The maximum angular velocity during exploration is expressed as "D = 1 - maximum angular velocity".

4. The underground radar device according to claim 2 or 3.

5. 2. The underground radar device according to claim 1, wherein the notification means is at least one of a display device that displays reliability information, a light emitting device that issues a light warning, and a sound emitting device that issues a warning sound.

6. A method for detecting buried objects underground by emitting electromagnetic waves into the ground and receiving the waves reflected at the boundary surface between materials with different dielectric constants, comprising: The reliability of the relative permittivity used to calculate the depth of the buried object is estimated based on the road surface condition of the measurement route and changes in the measurement speed, When the reliability of the dielectric constant is estimated to be low, a warning of poor depth accuracy is given to a user. A method for detecting buried objects using a ground-penetrating radar device.

7. 7. The buried object exploration method for an underground radar device according to claim 6, wherein the reliability of the dielectric constant is estimated using, as parameters for the information on the road surface condition of the measurement path, the presence or absence of puddles on the ground of the measurement path, and the inclination and maximum angular velocity of the measurement path, and using, as parameters for the information on the change in the measurement velocity, a change in maximum velocity during measurement.

8. The reliability of the relative dielectric constant used to calculate the depth of the buried object is defined as R, the presence or absence of a puddle on the buried object as A, the maximum speed during the search as B, the degree of change in the slope as C, and the maximum angular speed during the search as D. The weights of these parameters A, B, C, and D are respectively W Ａ , W Ｂ , W Ｃ , W Ｄ Then, it is estimated based on the following formula: [Equation 1] However, when there is a puddle on the buried object, A=0, and when there is no puddle, A=1. When the search limit speed is exceeded, B=0, and when it is not exceeded, B=1. The degree of change in the slope is expressed as "C = minimum value (degrees) / maximum value (degrees)" The maximum angular velocity during exploration is expressed as "D = 1 - maximum angular velocity".

8. The buried object exploration method for a ground penetrating radar device according to claim 7.

9. 7. The method for detecting buried objects using a ground-penetrating radar device according to claim 6, wherein the warning to the user is at least one of a display of reliability information, a light warning, and an audible warning.

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