JP3773353B2 - Method and apparatus for exploring buried object in underground propulsion method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a radar transmission / reception unit provided in a propulsion body emits a wave signal to the object while moving in the medium toward the object in the medium, and a reflected signal of the emitted wave signal from the object is emitted. Receiving, performing position survey of the object based on the received signal strength data of the reflected signal, and underground burial such as existing buried pipes when laying various pipes in the ground by underground propulsion method The present invention relates to a buried object exploration method in an underground propulsion method for preventing damage to objects.
[0002]
[Prior art]
Conventionally, as a method of detecting the position of underground objects such as underground pipes and underground structures, wave signals such as electromagnetic waves are radiated from the ground surface to the ground while moving on the ground surface. A two-dimensional image that receives a reflected signal that is reflected and uses coordinates (x, t) as the movement distance x of the ground surface with respect to the signal intensity of the received reflected signal and the reflection time t of the wave signal from the object Data is generated, image processing such as synthetic aperture processing and migration processing is performed on the two-dimensional image data, and the propagation speed of the wave signal in the ground is estimated to detect the position of the object.
[0003]
[Problems to be solved by the invention]
However, in the conventional propagation velocity estimation in the above-described position detection from the ground surface, in order to execute the above-described image processing with high accuracy, the computer processing performance effective and practical at the time of the present application is about Processing time of about 40 seconds is required, and in the underground propulsion method that requires forward monitoring in real time, the processing time must be significantly reduced. For example, in the case of the boremore method, which is a kind of underground propulsion method, the propulsion speed is about 30 cm / min as a standard, so a position detection method that can be processed in about several seconds as the processing time is required.
[0004]
In addition, when detecting the position from the ground surface, it may not always be possible to search from the ground surface in line with the direction of propulsion in the ground, and it is possible to accurately detect the position of an object in real time while propelling in the ground. It is desired that the propulsion head can be reliably prevented from being damaged by contact with the buried object. However, at present, the propulsion head is provided with a transmission / reception unit for an underground exploration radar, and only a function of judging the presence or absence of a front obstacle has been put into practical use. Not enough.
[0005]
The present invention has been made in view of the above-mentioned problems, and its purpose is to solve the above-mentioned problems, and in the underground propulsion method, it is possible to reliably prevent damage to buried objects such as buried pipes. It is in providing a method and apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve this object, the first characteristic configuration of the present invention relates to a buried object search method in the underground propulsion method, and as described in claim 1 of the claims, the radar provided in the propulsion unit. A transmission / reception unit radiates a wave signal to the object while moving in the medium toward the object in the medium, and receives the reflected signal from the object of the radiated wave signal, and received in the transmission / reception process A two-dimensional image data generating step for generating two-dimensional image data having coordinates (x, t) as a moving distance x toward the object with respect to the signal intensity of the reflected signal and a reflection time t of the wave signal from the object; , The signal intensity of the two-dimensional image data generated in the two-dimensional image data generation step is expressed as a specific movement distance x on the x-t plane constituted by the movement distance x and the reflection time t. Every definitive reflection time t, and the signal strength adding step of adding along each inclination corresponding to the plurality of the propagation velocity v _i that is set in advance in the medium of the wave signal, generated by the signal intensity addition step An object distance calculating step of identifying a propagation speed v _P in the medium from the convergence of the added reflected signal intensity for each propagation speed v _i and calculating a distance to the object using the propagation speed v _P ; When the distance calculated in the object distance calculating step is less than or equal to a predetermined value, the propulsion body is instructed to stop moving toward the object.
[0007]
The second characteristic configuration relates to a buried object exploration method in the underground propulsion method, and as described in claim 2 in the column of the claims, the radar transmission / reception unit provided in the propulsion body passes through the medium. A transmitting / receiving step of radiating a wave signal to the object while moving toward the object, and receiving a reflected signal from the object of the radiated wave signal, and the signal strength of the reflected signal received in the transmitting / receiving step A two-dimensional image data generating step for generating two-dimensional image data having a coordinate (x, t) as a moving distance x toward the object and a reflection time t of the wave signal from the object; and the moving distance x and the reflection time. The signal intensity of the two-dimensional image data generated in the two-dimensional image data generation step on the x-t plane constituted by t is the wave for each reflection time t at a specific movement distance x. Plurality of propagation and signal intensity summation step of summing along each inclination corresponding to velocity v _i, performed sequentially, the signal strength each propagation velocity generated by the adding process has been set in advance in the medium of the signal v amplitude values of the respective propagation velocity v set predetermined critical reflection time t _Bi following the area for each _i of the addition the reflected signal intensity for each _i is, when equal to or greater than a predetermined threshold value S _T, the propellant The point is to instruct the stop of the movement toward the object.
[0008]
The third characteristic configuration relates to a buried object exploration device in the underground propulsion method, and as described in claim 3 in the column of claims, the object moves while moving in the medium toward the object in the medium. A radar transmission / reception unit that radiates a wave signal to the object and receives a reflection signal of the radiated wave signal from the object is provided in the propulsion unit, and the movement toward the object with respect to the signal intensity of the reflection signal received by the radar transmission / reception unit A two-dimensional image data generating means for generating two-dimensional image data having a distance x and a reflection time t of the wave signal from the object as coordinates (x, t); and the moving distance x and the reflection time t. On the x-t plane, the signal intensity of the two-dimensional image data generated by the two-dimensional image data generating means is used for each reflection time t at a specific movement distance x for the medium of the wave signal. A signal intensity adding means for adding along each inclination corresponding to the plurality of the propagation velocity v _i that is set in advance in the summing reflected signal intensity of the signal intensity adding means wherein each propagation velocity v _i generated in each the amplitude value of the propagation velocity v set following areas predetermined critical reflection time t _Bi for each _i is, when equal to or greater than a predetermined threshold value S _T, instructs the stop of the movement towards the object of the propellant And a propulsion stop means.
[0009]
In the second and third characteristic configurations, the amplitude value of the added reflected signal intensity means the absolute value regardless of the polarity.
[0010]
The operation and effect will be described below.
According to the first characteristic configuration of the present invention, in the two-dimensional image generation step, characteristic points such as a maximum value and a minimum value in the two-dimensional image data obtained by displaying the reflected signal intensity by, for example, luminance display, When the radar transmitter / receiver is positioned forward in the traveling direction, it is arranged on a straight line on the xt plane, and when the object is positioned obliquely away from the radar transmitting / receiving unit's traveling direction, the ground surface Since the characteristic points of the reflected signal intensity are arranged on a straight line, the inclination (Δx / Δt) of the arrangement direction on the x-t plane is arranged similarly to the search image from Is the propagation velocity v of the wave signal in the medium, or when the reflection time t is the round-trip time between the radar transmitter / receiver and the object, it corresponds to half the value of the propagation velocity v, and the signal intensity The addition process is repeated for each predetermined moving distance x. By executing a predetermined distance in the arrangement direction at each irradiation time t, the propagation speed having the maximum convergence of the added reflected signal intensity among the preset propagation speeds v _i is determined as the propagation speed v _P in the medium. The reflection time t in which the added reflected signal intensity exceeds a predetermined threshold is extracted, and the distance to the object can be calculated from the propagation velocity v _P and the reflection time t, and the distance is a predetermined threshold. By instructing the propulsion unit to stop propulsion in the following cases, contact with the object can be reliably prevented, and damage to the object can be avoided in advance.
Even when the object is slightly off the traveling direction of the radar transmission / reception unit and is located in an oblique direction, if the distance to the object is far away, the characteristic point of the reflected signal intensity is substantially linear. The same processing can be performed by arranging them above, and even in such a case, contact with the object can be reliably prevented, and damage to the object can be avoided in advance.
[0011]
As described above, since the distance to the object can be calculated by a calculation process that simply repeats the four arithmetic operations in this way, the processing time can be significantly reduced as compared with the above-described conventional method, and the operator can move to the object. Compared with the case where the distance is manually determined from the array image of the maximum and minimum values of the reflected signal intensity of the two-dimensional image data by eye measurement or the like, the calculation of the distance is remarkably highly accurate and speeded up. It is possible to reliably prevent contact with the
[0012]
When the wave signal is an electromagnetic wave, a relationship of v = c ₀ / ε ^1/2 is established between the relative dielectric constant ε of the medium and the propagation speed v in the medium, where c ₀ is the speed of light. A similar effect can be obtained by setting the relative dielectric constant ε of the medium that uniquely corresponds to the propagation speed v in the medium, or an equivalent constant thereof, instead of setting the propagation speed v _i in advance.
By the way, when the medium is soil in the ground, for example, the relative permittivity ε varies depending on the soil quality, while the relative permittivity of ordinary river sand is 8 and the relative permittivity of clay is 15, whereas there is much groundwater. In the contained soil, the relative dielectric constant increases to about 80.
Therefore, according to this characteristic configuration, the relative dielectric constant ε of the medium is specified from the propagation velocity v _P in the medium in the first half of the object distance calculating step, or the plurality of propagations in the signal intensity adding step. When setting a plurality of relative dielectric constants ε _i instead of setting the speed v _i , since the relative dielectric constant ε is directly specified, the characteristics of the medium can be known simultaneously from the relative dielectric constant ε, for example, It is also possible to detect in advance when the medium itself is inconvenient, such as soil containing a lot of groundwater.
[0013]
According to the second or third feature configuration, an effect substantially similar to that of the first feature configuration described above instructs to stop the propulsion of the propulsion body without finally calculating the distance to the object. Therefore, it is possible to respond more promptly and more reliably prevent contact with the object. That is, in this characteristic configuration, a predetermined critical reflection time set for each propagation velocity v _i of the amplitude value of the added reflected signal intensity for each propagation velocity v _i generated by the signal intensity addition step or means. t _Bi as follows in the area is, if equal to or greater than a predetermined threshold value S _T, given its coordinate point (v _i, t _j) from the always equal to or less than a predetermined critical distance, the propellant is on the object It is possible to easily and accurately determine that the vehicle is close to the distance.
[0014]
Here, the relative than back round noise level when the back round noise including stationary noise and random noise of the reflected signal intensities received by the radar transceiver unit as the threshold value S _T obtained by adding by the signal strength adding step or means By making the signal value larger than a certain level, it is possible to make a highly accurate determination with the influence of these noises removed. In particular, the amplitude value of the sum reflection signal intensity is plotted on the v-t plane, when determining visually generate the propagation velocity distribution image, by performing threshold processing by the threshold value S _T, easily An accurate determination can be made. As the threshold value S _T, for example, (about 3.16 times the amplitude) relatively 10dB than the back round noise level greater value is desirable.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the buried object exploration method and the buried object exploration device in the underground propulsion method according to the present invention are applied to exploration of buried objects such as underground pipes will be described with reference to the drawings.
[0016]
As shown in FIG. 1, a propulsion device system 10 used in the underground propulsion method is connected to a propulsion head 11 for underground propulsion movement having a drill for drilling at the tip, and a base end side of the propulsion head 11. The connecting rod 13 is connected to the propulsion drive device 12 disposed on the ground, and the control vehicle 15 is equipped with a control device 14 for controlling these. In addition, this structure is the same structure as the propulsion apparatus used for the conventional flow molding method.
[0017]
In the present embodiment, the propulsion head 11 is supplied with a single pulse wave signal having a center frequency of 100 MHz to 1 GHz, for example, which can be transmitted through the medium (ground in the present embodiment) with low loss, at the tip of the propulsion head 11. The reflected signal of the wave signal is a part of the reflected wave that is radiated from the front and incident on the object 1 such as an embedded pipe embedded forward in the propulsion direction of the propulsion head 11 and reflected and scattered on the surface thereof. As shown in FIG. Specifically, the radar transmission / reception unit 2 includes an antenna that transmits and receives electromagnetic waves and an electronic circuit unit that forms an electronic circuit for transmission and reception.
Further, a position detection processing device 3 for processing the reflected signal received by the radar transmitting / receiving unit 2 and specifically executing the method of the present invention is provided in the control vehicle 15 on the ground together with the control device 14. This position detection processing device 3 executes the main steps of the method of the present invention described later by computer processing. Further, this computer processing is performed by processing a predetermined execution program with a normal stored program computer system. What remove | excluded the part which concerns on the said propulsion apparatus system 10 from the above structure comprises the embedded object search apparatus which concerns on this invention, Even if a part or all of the said propulsion apparatus system 10 is included in an embedded object search apparatus. The function of the entire system is substantially the same.
[0018]
As shown in FIG. 2, the position detection processing device 3 includes an arithmetic processing unit 4 having a hardware configuration equivalent to a general computer system including a microprocessor, a semiconductor memory, a magnetic storage device, and other peripheral devices, As an input / output device, an analog signal input unit 5 capable of inputting the reflected signal, which is an analog signal received by the radar transmission / reception unit 2, and an A / D conversion unit 6 that quantizes the analog signal in real time with a predetermined resolution, An image display device 7 such as a CRT display or a liquid crystal display for displaying various two-dimensional image data and processing results, which will be described later, and a keyboard device 8 capable of keying various commands are provided. Since the detailed hardware configuration of the position detection processing device 3 is the same as that of a general computer system as described above, a detailed description is omitted.
[0019]
On the other hand, as shown in FIG. 2, the functional configuration of the position detection processing device 3 includes a moving distance x toward the object 1 with respect to the signal intensity of the reflected signal received by the radar transmitting / receiving unit 2 and the wave signal. A two-dimensional image data generating means 20 for generating two-dimensional image data having the reflection time t from the object 1 as coordinates (x, t), and an x-t plane constituted by the moving distance x and the reflection time t The signal intensity of the two-dimensional image data generated by the two-dimensional image data generating means 20 is set to a plurality of preset wave signals in the medium for each reflection time t _j at a specific movement distance x. propagating a signal intensity adding means 21 for adding along each inclination corresponding to velocity v _i, the signal intensity adding means 21 wherein each propagation speed of the generated the sum reflected signal intensity S _ij for each propagation velocity v _i in the v _i the amplitude value of the set predetermined threshold reflection time following area t _Bi for each is, if equal to or greater than a predetermined threshold value S _T, to the control unit 14 so as to stop the propulsion of the propulsion head 11 From the convergence of the added reflected signal intensity S _ij for each propagation velocity v _i generated by the signal intensity adding means 21 and the propulsion stopping means 22 that gives an instruction to stop propulsion or issues an alarm to the operator. The arithmetic processing unit 4 includes an object distance calculating unit 23 that specifies a propagation velocity v _P in the medium and calculates a distance to the object 1 using the propagation velocity v _P.
[0020]
As shown in FIG. 3, in the present embodiment, the buried object exploration device includes a transmission / reception step S1, a two-dimensional image data generation step S2, a signal intensity addition step S3, a propulsion stop step S4, and an object distance calculation step S5. Each step is sequentially executed to calculate the distance between the propulsion head 11 and the object 1 and to search for the position of the object 1. The propulsion stop step S4 is executed only when a predetermined condition is satisfied.
[0021]
In the transmission / reception step S1, the radar transmission / reception unit 2 moves toward the object 1 by the propulsion of the propulsion head 11, and radiates the wave signal toward the object 1, that is, forward in the propulsion direction. The reflected signal from the object 1 of the wave signal is received. The received reflected signal is subjected to amplification processing or noise removal processing as necessary, and transmitted to the position detection processing device 3 in real time.
[0022]
In the two-dimensional image data generation step S2, the two-dimensional image data generation means 20 receives the reflected signal received in the transmission / reception step S1 by the analog signal input unit 5, and then the A / D conversion unit 6 The amplitude value of the reflected signal, that is, the reflected signal intensity is quantized into binary data having a predetermined number of bits at a predetermined sampling interval (0.1406 ns in this embodiment). Therefore, the travel distance x toward the object 1 can be calculated every time the received signal is received by a stroke meter or the like, and the reflection time t from the object 1 of the wave signal timed at the travel distance x and the sampling interval. 2D image data is generated with the coordinates (x, t) as.
[0023]
As an example of the two-dimensional image data, as shown in FIG. 4, the image size is composed of 200 pixels on the horizontal axis x (movement distance x) and 256 pixels on the vertical axis y (reflection time t). Regarding the movement distance x, since the reflected signal is not received on the actual movement distance x _P , that is, on the propulsion direction side (+ x direction) from the current position x _P of the propulsion head 11, the reflection signal intensity is set to 0 and the two-dimensional. Image data has been generated. In addition, the reflection time t actually represents the sampling timing of the propagation time when the wave signal reciprocates the object 1 with the wave signal emission time being 0 ns, and the reflection time t is measured from 0 ns to 36 ns. The received reflected signal is quantized at a sampling point of 256 reflection times t for each moving distance x.
[0024]
The reflected signal intensity quantized with a predetermined number of bits is displayed in the image display device 7 with an intensity of 0 at medium luminance, high luminance when the polarity of the signal intensity is positive, and negative. Is displayed with low brightness. The number of gradations of display luminance is determined by the number of quantization bits. In FIG. 4, for the sake of convenience, the intermediate luminance is displayed in a paper background color, the high luminance portion is indicated by a broken line, and the low luminance portion is indicated by a solid line.
[0025]
In order to understand the two-dimensional image data shown in FIG. 4 more visually, FIG. 5 shows reflected signal waveforms in three dimensions for the three points of the movement distance x.
[0026]
By the way, in the case of the two-dimensional image data of FIG. 4, since the locus T of the received reflected signal is a straight line, the object is located at the intersection x ₀ (near 80 pixels of the moving distance x) with the horizontal axis x on the extension line of the straight line. If 1 is present and the vehicle goes straight ahead, it can be seen that the object 1 collides. Further, if the trajectory T of the reception reflected signal is not a straight line but a hyperbola, it can be understood that the object 1 is shifted obliquely from the propulsion direction of the propulsion head 11.
As described above, if it is determined from the image display of the two-dimensional image data that the object 1 is present ahead of the propulsion direction, each process after the next step is performed in order to accurately calculate the distance to the object 1. .
[0027]
Before executing the signal intensity adding step S3, first, a plurality of propagation speeds v of the wave signal in the medium are temporarily set and tabulated. Here, the relationship between the propagation speed v and the reflection time t at a certain moving distance x is represented by t = 2 (x ₀ −x) / v, and the inclination of the locus T is twice the reciprocal of the propagation speed v. It corresponds to. Note that the relationship between the inclination of the trajectory T and the propagation velocity v changes depending on the way of taking the coordinate axes of the two-dimensional image data and the reflection time t as a one-way propagation time instead of a round trip time.
In this embodiment, the plurality of propagation velocities v _i are temporarily set in advance so as to satisfy the relationship defined by the following equation (1). i is a natural number of 1-20.
[0028]
[Expression 1]
log ₁₀ (v / c ₀ ) = − 0.4− (i−1) * 0.02
[0029]
In the signal intensity adding step S3, as shown in FIG. 3, the signal intensity adding means 21 sequentially selects the 20 temporarily set propagation speeds v _i in the order of i = 1 to 20 (substep #). 1).
Incidentally, each of the propagation velocity v _i is not to select the one previously temporarily set, may be to calculate the number 1 sequentially sets each of said propagation velocity v _i.
[0030]
Next, for the one propagation velocity v _i selected or set in the sub-step # 1, the two-dimensional image data generating step is performed along the inclination on the xt plane specified by the propagation velocity v _i. An addition start point for adding the signal intensities of the two-dimensional image data generated in S2 is set. Specifically, the reflection time t _j corresponding to each pixel in the vertical axis y direction at the moving distance x _P that is the current position is set (substep # 2).
[0031]
Next, starting from the coordinate point (x _P , t _j ) composed of the movement distance x _P and the reflection time t _j set in substep # 2, the propagation velocity v _i set in substep # 1 is set. The reflected signal intensity data from the moving distance x _P to the moving distance x ₁ for 16 pixels in the −x direction is added at an inclination (Δx / Δt) corresponding to a half, and the added reflected signal intensity is _expressed as S _ij. (Substep # 3). Here, the length from the movement distance x _P to the movement distance x ₁ corresponds to about 20 cm as a propulsion distance.
In this way, the range of addition is limited because the reflected signal intensity received as the distance from the object 1 decreases, and the reflected signal intensity at which the S / N ratio deteriorates is added in the signal intensity adding step S3. The S / N ratio of the added reflected signal intensity S _ij itself, which is the addition result, can be improved, and the determination of the convergence of the added reflected signal intensity S _ij in the subsequent process becomes clearer. is there. In addition, since a lot of data is not repeatedly added, the processing time can be shortened.
[0032]
Then, the added reflected signal intensity S _ij is plotted on a vt plane with the horizontal axis representing the propagation velocity v _i and the vertical axis representing the reflection time t _j , thereby generating a propagation velocity distribution image (substep). # 4).
[0033]
In the above manner, the substeps # 1 to # 4 are repeated in the range of i = 1 to 20 and j = 1 to 256 to complete the propagation velocity distribution image, and the signal intensity adding step S3 is completed. It should be noted that any of i and j iteration loops may be first.
[0034]
As an example of the propagation velocity distribution image, as shown in FIG. 6, the horizontal axis i (propagation velocity v _i , i = 1 to 20, several pixels in the horizontal axis direction are displayed as one data), the vertical axis y (reflection time t _j ) Configured as 256 pixels. Further, the added reflected signal intensity S _ij is displayed in the image display device 7 in the same way as the two-dimensional image data illustrated in FIG. 3 when the intensity 0 is displayed at intermediate luminance and the polarity of the signal intensity is positive. It is displayed with high brightness and low brightness when negative. Further, for the sake of convenience, the intermediate luminance is displayed as a paper background color, the high luminance portion is indicated by a broken line, and the low luminance portion is indicated by a solid line.
[0035]
In the propulsion stopping step S4, the propulsion stop means 22, to the addition reflected signal intensity S _ij of the signal intensity addition each step the respective propagation velocity generated by v _i, smaller than a predetermined threshold S _T is 0, and only made with the threshold S _T or more, subjected to a threshold process of saving while maintaining intact gradation (substep # 7), the amplitude value of the addition the reflected signal intensity S _ij after the threshold processing It is determined for each propagation velocity v _i whether or not it exists within a predetermined critical reflection time t _Bi or less (substep # 8), and if not, the object distance calculation in the next step is performed. The process proceeds to step S5, and if it exists, the control device 14 is instructed to stop propulsion to stop the propulsion of the propulsion head 11 (sub step # 9), and the process proceeds to the object distance calculating step S5.
[0036]
Here, as the threshold value S _T, than back round noise level when the back round noise including stationary noise and random noise of the reflected signal intensities the radar transceiver 2 receives the signal intensity adding means 21 adds Use a relatively large value of 10 dB (approximately 3.16 times in amplitude). As a result, by setting the threshold value _ST to a signal value larger than the background noise level by a certain level or more, it becomes possible to make a highly accurate determination with the influence of these noises removed.
Each propagation velocity v _i and each corresponding critical reflection time t _Bi have a relation represented by the following equation (2), and the critical distance d _B calculated by the equation (2) is constant between i. Therefore, the distance is set in advance so as to be the shortest distance (for example, 30 cm) at which the approach to the object 1 is allowed.
[0037]
[Expression 2]
d _B = v _i * t _Bi / 2
[0038]
In the object distance calculating step S5, the object distance calculating means 23 determines the convergence degree from the maximum value of the added reflected signal intensity S _ij of the propagation velocity distribution image generated in the signal intensity adding step S3, and determining the propagation velocity v _P and the moving distance x reflected at _P time t _P in the medium that gives the maximum value, the distance of the to the object 1 (x ₀ -x _P) is calculated by the number 3 in the following equation.
[0039]
[Equation 3]
(X ₀ −x _P ) = v _P * t _P / 2
[0040]
In the case of the propagation velocity distribution image shown in FIG. 6, i = 11, ie, v _P = 7.536 cm / ns (7.536 * 10 ⁷ m / s), j = 92, ie, t _j = 12.93 ns. , (X ₀ −x _P ) = 48.73 cm.
[0041]
Furthermore, in addition to the distance calculation of the to the object 1, because the wave signal is an electromagnetic wave, the relationship between the relative dielectric constant ε of the propagation velocity v and the medium, the c ₀ as the speed of light, v = c ₀ / It is expressed by ε ^1/2 , and from the result of the propagation velocity v _P , it is found that ε = 15.8 (clay), and it can be determined that it does not contain a large amount of groundwater or the like.
[0042]
Next, in order to confirm the exploration accuracy of the buried object searching method and apparatus, an experimental example will be described in which the buried object searching method is performed in the experimental soil tank 16 shown in FIG.
In this experiment, a steel pipe having a diameter of 25 mm is used as the object 1, and the two-dimensional image data generation step S2 and the signal intensity addition step are performed while moving the propulsion head 11 from the object 1 to a distance of 10 cm. S3 and the propulsion stop step S4 were respectively executed to obtain two-dimensional image data, an added reflection signal intensity S _ij , and an added reflection signal intensity S _ij after the threshold processing.
[0043]
FIG. 8 shows the two-dimensional image data displayed with the image size of the movement distance x (0 to 160 pixels) on the horizontal axis and the reflection time t (0 to 20 nsec) on the vertical axis.
In FIG. 9, the added reflected signal intensity S _ij before the threshold processing is represented by v−, where the horizontal axis represents the propagation velocity v _i (i = 1 to 20) and the vertical axis represents the reflection time t _j (0 to 20 nsec). A propagation velocity distribution image plotted on the t plane is shown.
The reflected signal intensity shown in FIG. 8 and the added reflected signal intensity _Sij shown in FIG. 9 are displayed in the same manner as in FIGS. Display high brightness when positive, low brightness when negative, and for the sake of convenience, intermediate brightness is displayed on paper, high brightness areas are indicated by broken lines, low brightness areas are indicated by solid lines, and noise is displayed. Omitted and displayed in a simulated manner.
Further, the relationship between each propagation velocity v _i and each corresponding critical reflection time t _Bi is shown by a one-dot chain line in FIG. Here, the critical distance d _B calculated by the number 2 is set to 30 cm. Therefore, the amplitude value of the signal intensity to promote stopping area of the upper than the critical reflection time t _Bi lines indicated by dash-dotted line (reflection time is small) is if there is the threshold value S _T or more portions, of the propulsion head 11 Instruct to stop propulsion.
[0044]
Further, from the propagation velocity distribution image shown in FIG. 9, the relative dielectric constant ε of the medium, which is uniquely determined from the relationship of v = c ₀ / ε ^1/2 corresponding to the propagation velocity v _i having the highest convergence, is 17. Since the relative permittivity of the soil used in this experimental example separately measured in advance is about 18, the propagation speed estimation accuracy in the medium in the buried object search method according to the present invention is sufficiently practical. It was confirmed that the level was
[0045]
FIG. 10 shows the summed reflected signal intensity S _ij after the threshold processing, the horizontal axis indicates the propagation velocity v _i (i = 1 to 20), the vertical axis indicates the reflection time t _j, and the distance d (to the object 1). 0 to 100 cm) and shown as a propagation velocity distribution image plotted on the vd plane. In this case as well, the intensity 0 is displayed with an intermediate luminance, the signal intensity is displayed with a high luminance when the polarity is positive, and the signal intensity is displayed with a low luminance when the signal intensity is negative. The high luminance portion is indicated by a broken line, the low luminance portion is indicated by a solid line, and the critical distance d _B (30 cm) is indicated by a one-dot broken line.
In FIG. 10, since the threshold processing is performed, the noise and weak signal portions omitted in FIG. 9 are not displayed because they are removed.
[0046]
Another embodiment will be described below.
<1> In the calculation of the added reflected signal intensity S _ij in sub-step # 3 in the signal intensity adding step S3, the moving distance x ₁ is not necessarily a position corresponding to 16 pixels in the −x direction from the moving distance x _P. It doesn't matter.
For example, the position of x = 0 where the transmission / reception process S1 is started may be used, or the position where the effective signal intensity is received for the first time in the transmission / reception process S1 may be used as appropriate.
[0047]
<2> In the above embodiment, after executing the signal intensity adding step S3, the propulsion stopping unit 22 does not execute the propulsion stopping step S4, and the object distance calculating unit 23 performs the object distance calculating step S5. run, where if the distance to the calculated the object 1 is less than the critical distance d _B, may be instructed to stop the propulsion of the propulsion head 11.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a propulsion device system to which an embedded object searching method and apparatus according to the present invention are applied. FIG. 2 is a block diagram showing a position detection processing apparatus for executing an embedded object searching method according to the present invention. FIG. 4 is an explanatory view showing an example of two-dimensional image data generated in the two-dimensional image data generating step. FIG. 5 is an explanatory view showing an example of the embedded object searching method according to the present invention. FIG. 6 is an explanatory diagram showing an example of a propagation velocity distribution image generated in the signal intensity addition process. FIG. FIG. 8 is an explanatory diagram showing the experimental soil tank used in the example. FIG. 8 is an explanatory diagram showing the two-dimensional image data generated in the two-dimensional image data generating step in the present experimental example. FIG. Generated before threshold processing Explanatory view showing a propagation velocity distribution image after the threshold process in the diagram Figure 10 This experiment example showing velocity distribution image EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 1 Object 2 Radar transmission / reception part 3 Position detection processing apparatus 4 Operation processing part 5 Analog signal input part 6 A / D conversion part 7 Image display apparatus 8 Keyboard apparatus 10 Propulsion system 11 Propulsion head 12 Propulsion drive apparatus 13 Connecting rod 14 Control apparatus 15 Control wheel 16 Experimental soil tank 20 Two-dimensional image data generation means 21 Signal intensity addition means 22 Promotion stop means 23 Object distance calculation means S1 Transmission / reception process S2 Two-dimensional image data generation process S3 Signal intensity addition process S4 Promotion stop process S5 Object distance Calculation process

Claims (3)

A transmission / reception process in which a radar transmission / reception unit provided in the propulsion body emits a wave signal to the object while moving in the medium toward the object in the medium, and receives a reflection signal of the emitted wave signal from the object When,
Two-dimensional image data for generating two-dimensional image data having coordinates (x, t) as a moving distance x toward the object with respect to the signal intensity of the reflected signal received in the transmission / reception step and a reflection time t of the wave signal from the object An image data generation process;
The signal intensity of the two-dimensional image data generated in the two-dimensional image data generation step on the x-t plane constituted by the movement distance x and the reflection time t is the reflection time at a specific movement distance x. a signal intensity addition step of adding along each slope corresponding to a plurality of preset propagation velocities v _i in the medium of the wave signal at every t;
The propagation velocity v _P in the medium is specified from the convergence of the added reflected signal intensity for each propagation velocity v _i generated in the signal intensity addition step, and the distance to the object is determined using the propagation velocity v _P. Sequentially executing the object distance calculating step of calculating
A buried object exploration method in an underground propulsion method, wherein when the distance calculated in the object distance calculation step is equal to or less than a predetermined value, the propulsion body is instructed to stop moving toward the object. A transmission / reception process in which a radar transmission / reception unit provided in the propulsion body emits a wave signal to the object while moving in the medium toward the object in the medium, and receives a reflection signal of the emitted wave signal from the object When,
Two-dimensional image data for generating two-dimensional image data having coordinates (x, t) as a moving distance x toward the object with respect to the signal intensity of the reflected signal received in the transmission / reception step and a reflection time t of the wave signal from the object An image data generation process;
The signal intensity of the two-dimensional image data generated in the two-dimensional image data generation step is expressed as a reflection time at a specific movement distance x on an x-t plane composed of the movement distance x and the reflection time t. a signal intensity addition step of adding along each inclination corresponding to a plurality of preset propagation velocities v _i in the medium of the wave signal every t,
An amplitude value in a region of a predetermined critical reflection time t _Bi or less set for each propagation velocity v _i of the added reflected signal strength for each propagation velocity v _i generated in the signal intensity addition step is predetermined. buried objects exploration method in underground jacking method, characterized in that the when equal to or greater than the threshold value S _T, instructs the stop of the movement towards the object of the propellant. Providing a propulsion unit with a radar transmission / reception unit that radiates a wave signal to the object while moving toward the object in the medium, and receives a reflected signal from the object of the radiated wave signal,
Generates two-dimensional image data with coordinates (x, t) representing a moving distance x toward the object with respect to the signal intensity of the reflected signal received by the radar transceiver and a reflection time t of the wave signal from the object 2 Dimensional image data generating means;
The signal intensity of the two-dimensional image data generated by the two-dimensional image data generation unit is expressed as a reflection time t at a specific movement distance x on an x-t plane constituted by the movement distance x and the reflection time t. Signal intensity adding means for adding each wave signal along each slope corresponding to a plurality of preset propagation velocities v _i in the medium;
An amplitude value in a region of a predetermined critical reflection time t _Bi or less set for each of the propagation speeds v _i of the added reflected signal intensity for each of the propagation speeds v _i generated by the signal intensity adding means is a predetermined value. If equal to or greater than the threshold value S _T, buried object locator of the ground jacking method comprising a propulsion stop means for instructing a stop of the movement towards the object of the propellant.

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