JP2007263882A - Underground exploration equipment - Google Patents

Abstract

An underground exploration device having excellent discrimination of weak reflected waves from a buried object is provided.
An underground exploration device 100 includes a carriage 10 that moves on the ground surface, a transmission antenna 11 that is mounted on the carriage 10 and radiates electromagnetic waves for exploration into the ground, and a carriage 10 that is spaced apart from the transmission antenna 11 by a different distance. The first and second receiving antennas (12, 13) for receiving the reflected waves from the buried object, the buffer memory 21 for storing the received signals of both receiving antennas, and at least one received reception A depth calculation circuit 24 that calculates the depth of the buried object from the signal, an identification circuit 22 that compares the two received signals and identifies the buried object of the received signal based on both the moving direction distance and the depth of the carriage 10. A correction circuit 23 that corrects the carriage movement direction deviation of both received signals of the buried object from the depth value, and a composite display circuit 25 that combines the corrected both received signals.
[Selection] Figure 1

Description

  The present invention relates to an underground exploration device for exploring a buried object by emitting an electromagnetic wave for exploration in the ground and receiving a reflected wave from the buried object.

  In conventional underground exploration devices, exploration electromagnetic waves are radiated from the transmitting antenna toward the ground, and the exploration electromagnetic waves are reflected at the interface between the earth and sand and the buried object having different electrical properties, and the reflected waves are received by the receiving antenna. The distance to the reflecting object is obtained from the propagation time to reach the object, and the underground exploration device obtains a desired underground image by moving the ground surface.

  Since this underground image is formed based on the received signal received by one receiving antenna, it is weakly reflected from small-sized embedded objects due to the influence of interference electromagnetic waves due to reflection from the ground surface and leakage along its surface. There was a limit to identifying waves.

  In order to solve such a problem, Patent Document 1 discloses that a plurality of receiving antennas are arranged so that the left and right are symmetrical with respect to the center line of the transmitting antenna to reduce the influence of the interference electromagnetic wave from the embedded object. A technique for discriminating weak reflected waves is disclosed.

  In addition, since it is necessary to accurately measure the relative dielectric constant in the ground in order to accurately measure the depth of the buried object, Patent Document 2 accurately describes the relative dielectric constant in the ground using two receiving antennas. A technique for measuring the depth of a buried object is disclosed.

Japanese Patent Laid-Open No. 11-166977 Japanese Patent Laid-Open No. 11-84020

  The technique of Patent Document 1 is small by arranging a transmitting antenna at the center of two receiving antennas, receiving the reflected waves in both directions from the embedded object, creating two underground images, and superimposing them. This makes it possible to identify shaped objects.

  Since the device shown in Patent Document 1 has the same path length from the transmitting antenna to the two receiving antennas, it is easy to distinguish the signal from the embedded object from noise and interference electromagnetic waves by simply adding both received signals. It has the advantage of being. However, on the other hand, there is a drawback that it is not possible to obtain the effect due to the uneven arrangement of the receiving antenna with respect to the transmitting antenna.

  For example, as shown in Patent Document 2, by using an underground exploration device that arranges a transmitting antenna and two receiving antennas on a straight line at a predetermined distance in a horizontal direction, an accurate depth and relative permittivity of an embedded object can be obtained. Although it is possible to measure, such a measurement is impossible in the prior art of Patent Document 1.

  However, in the prior art of Patent Document 2, since the length of each path from the transmitting antenna to the two receiving antennas is different, the search electromagnetic wave radiated from the transmitting antenna is reflected by the same embedded object, The received path and angle are different. For this reason, the display position of the embedded object in the obtained underground image is different, and there is another problem that it is not possible to display it as it is.

  Therefore, the underground exploration device according to the present invention has the function of measuring the accurate depth shown in Patent Document 2 while maintaining the identification function by superimposing small-shaped embedded objects as shown in Patent Document 1. The object is to provide an underground exploration device that combines the two.

  In order to achieve the above object, an underground exploration apparatus according to the present invention is different from a transmission vehicle that is a carriage that moves on the ground surface, a transmission antenna that is mounted on the carriage and radiates electromagnetic waves for exploration, and the transmission antenna. Based on at least one received signal, first and second receiving antennas that are mounted on a carriage at a distance and receive reflected waves from an embedded object, a buffer memory that stores received signals from both receiving antennas, respectively A depth calculation circuit that calculates the depth, an identification circuit that compares both received signals and identifies the embedded object of the received signal based on both the moving direction distance and the depth of the carriage, and both received signals of the identified embedded object It is characterized by comprising a correction circuit that corrects the carriage movement direction deviation from the depth value, and a combined display circuit that combines both corrected received signals.

  Further, in the underground exploration device according to the present invention, the composite display circuit is characterized in that the composite display circuit combines by correcting the sum of the two received signals.

  Furthermore, in the underground exploration apparatus according to the present invention, the composite display circuit is characterized in that the composite display circuit performs synthesis by calculating a difference between both corrected reception signals.

  Furthermore, in the underground exploration apparatus according to the present invention, the composite display circuit is characterized in that it combines by a product operation of both corrected reception signals.

  By using the present invention, there is an effect that it is possible to provide an underground exploration device having two functions of measuring an accurate depth while maintaining a function of identifying a small-sized embedded object.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the underground exploration device 100. The underground exploration device 100 radiates exploration electromagnetic waves in the ground mounted on the carriage 10, the carriage 10 that moves on the ground surface by the wheels 31, the rotary encoder 14 that detects the movement direction and distance of the carriage 10, and the like. A transmission antenna 11; first and second reception antennas (12, 13) that are mounted on the carriage 10 at a different distance from the transmission antenna 11 and receive a reflected wave from an embedded object; and a control unit 15. Contains.

  The control unit 15 includes a buffer memory 21 that stores reception signals of both reception antennas (12, 13), a depth calculation circuit 24 that calculates the depth of the embedded object from at least one stored reception signal, and both reception signals. And the identification circuit 22 for identifying the embedded object of the received signal based on both the moving direction distance and the depth of the carriage 10 and the carriage movement direction deviation of both received signals of the identified buried object are corrected from the depth value. A correction circuit 23, a combined display circuit 25 that combines the corrected reception signals, and an operation switch 26 are provided.

  Note that the composite display circuit 25 performs calculation display described later in response to an input from the operation switch 26, and provides various information regarding the embedded object to the operator.

  FIG. 2 shows a transmission path of the electromagnetic wave for exploration when the underground exploration device 100 moves on the buried pipe 40 along the ground surface. In the underground exploration device 100, the transmitting antenna 11 and the receiving antenna 1 (12) are arranged with a distance a apart, and the transmitting antenna 11 and the receiving antenna 2 (13) are arranged with a distance "a + b" apart. Yes. FIG. 2A shows a state in which the apparatus 100 has moved a distance X from the measurement start point and has moved onto the buried pipe 40, and FIG. 2B shows that the apparatus 100 has moved a distance c in the traveling direction (X + c). Shows the state.

  In the state of FIG. 2A, the search electromagnetic wave radiated from the transmission antenna 11 is reflected by the boundary surface of the buried tube 40 and reaches the reception antenna 13 in T2 time. Hereinafter, this transmission path is referred to as a parallel type 2. In the state of FIG. 2B, the search electromagnetic wave radiated from the transmission antenna 11 is reflected by the boundary surface of the buried tube 40 and reaches the reception antenna 12 in T1 time. Hereinafter, this transmission path is referred to as a parallel type 1. The apparatus 100 calculates the depth d of the buried pipe 40 from the relative dielectric constant calculated by the known technique of Patent Document 2 based on the separation distance of the transmission / reception antennas (11, 12, 13) and the arrival times T2, T1. . A description of the calculation method of the relative permittivity and the depth d is omitted.

  FIG. 3 shows an underground image obtained by the underground exploration device 100, and shows an outline of processing for correcting the underground image based on the installation position of the receiving antennas (12, 13). The echo of the same embedded object in the parallel type 1 obtained by the receiving antenna (12) is indicated by a broken line, and the echo of the same embedded object in the parallel type 2 obtained by the receiving antenna (13) is indicated by a solid line.

  As shown in the underground image of FIG. 3, the depth is the same, but the echo display position and shape do not match. This is due to the distance between the transmitting and receiving antennas. Therefore, in the present embodiment, the identification circuit 22 executes a process of searching for the echo of the same buried object at the same depth from the underground images obtained by the parallel type 1 and the parallel type 2. The echo of the same embedded object obtained by the identification circuit 22 is corrected by the following process.

  With reference to the receiving antenna 13, the distance from the receiving antenna 13 to the echo (broken line) of the same embedded object in the parallel type 1 is "b + a / 2", and the echo of the same embedded object in the parallel type 2 from the receiving antenna 13 (solid line) ) Is “(a + b) / 2”. Since the offset distance between the two echoes is “b / 2”, the echoes of the same embedded object coincide with each other by giving this horizontal offset. In the present embodiment, the horizontal direction offset processing is executed by the correction circuit 23.

  FIG. 4 shows an echo composite image of the underground image obtained by the underground exploration device 100. The echo of the same embedded object is identified by the above-described identification circuit 22 from the echo by the reception antenna R1 (12) and the echo by the reception antenna R2 (13), and the correction circuit 23 corrects it by giving a horizontal offset. Further, the composite display circuit 25 displays the echoes in a superimposed manner.

  FIG. 5 shows calculation display (C, D) using the received signals of (A) parallel type 1 and (B) parallel type 2 obtained by the underground exploration device 100. In addition, four arrows in the underground image indicate the positions of the buried pipes, and echoes of the two buried pipes close to each other and the other two buried pipes are shown.

  The calculation display by the composite display circuit 25 is to emphasize the correlated data between the two images by calculating the respective data of the two parallel type 1 and parallel type 2 received signals. For example, the (C) sum operation shown in FIG. 5 is an operation that takes the sum of the parallel type 1 and the parallel type 2, and a smooth image is obtained by the averaging effect. It can be seen that echoes from two adjacent buried pipes are emphasized and displayed as distorted echoes in the sum calculation of FIG.

  The (D) difference calculation shown in FIG. 5 is an operation for obtaining a difference between the parallel type 1 and the parallel type 2, and the correlated data is weakened and the noise data is strengthened. Therefore, it can be seen that the measurement is normal when there is no noise abnormal data in the difference calculation. As described above, the difference calculation is used when the measurement result is evaluated, and is used for data verification.

  FIG. 6 shows the result of emphasis processing of the cavity and the buried pipe by the received signal measured by the underground exploration device 100. The (E) product operation shown in FIG. 6 is an operation for obtaining a product of the parallel type 1 and the parallel type 2, and makes correlated data clear. Also, it is shown as (simple) to distinguish from other product operations. (F) Product calculation (negative polarity) shown in FIG. 6 is obtained by multiplying only the negative polarity data of parallel type 1 and parallel type 2 and multiplying the calculation result by “−1”, thereby making the cavity reflection clear. Become. This is because, for example, in the underground exploration device 100, the reflected wave from the cavity often indicates the negative electrode, and conversely, the reflected wave of the positive electrode is obtained from the buried pipe. It becomes possible to make it.

  The (G) product calculation (positive polarity) shown in FIG. 6 clarifies buried pipe reflection and the like by accumulating only the positive polarity data of the parallel type 1 and the parallel type 2. In addition, (H) product calculation (bipolarity) makes the cavity reflection and buried pipe reflection clear by taking the sum of (F) product calculation (negative polarity) and (G) product calculation (positive polarity). .

  Note that there are cases where the relative permittivity in the ground is not uniform or the electromagnetic wave transmission path may not follow the simple modeling shown in FIG. 2 or FIG. Even if processing or correction processing is used, an image shift occurs. Therefore, in the present embodiment, for example, after obtaining the product operation (positive polarity or bipolar), the position where the peak of the echo is maximized is again found by the identification circuit 22 and recorrected by the correction circuit 23 at the subsequent stage. . By this processing, it is possible to deal with the underground image blur. Such re-identification and re-correction may be processed automatically or may be started manually.

  As described above, by using the underground exploration device according to the present embodiment, the underground exploration device having both the identification function of the small-shaped embedded object and the function of measuring the accurate depth is provided. It becomes possible to do.

  In the present embodiment, the flow of echo synthesis display using the received signals of the single parallel type 1 and the parallel type 2 has been shown. However, the present invention is not limited to this, and the parallel type 1 measured multiple times and It is also possible to use a reception signal with the parallel type 2. In this case, it is possible to reduce an error due to non-uniformity of a medium such as earth and sand as compared with a case where a single received signal is used.

1 is an overall configuration diagram of an underground exploration device according to an embodiment of the present invention. An electromagnetic wave transmission path will be described. It is a schematic diagram which shows the outline | summary which correct | amends an underground image with the installation position of a receiving antenna. It is a composite image figure of an underground image. It is an image figure of the calculation display obtained by the underground exploration device. It is an image figure of the calculation display obtained by the underground exploration device.

Explanation of symbols

  10 trolleys, 11 transmitting antennas, 12 receiving antennas, 13 receiving antennas, 14 rotary encoders, 15 control units, 21 buffer memories, 22 identification circuits, 23 correction circuits, 24 depth calculation circuits, 25 composite display circuits, 26 operation switches, 31 Wheels, 40 buried pipes, 100 underground exploration equipment.

Claims (4)

A carriage that moves on the ground surface, a transmission antenna that is mounted on the carriage and radiates electromagnetic waves for exploration, and a first antenna that receives a reflected wave from an embedded object that is mounted on the carriage at a different distance from the transmission antenna. A second receiving antenna;
A buffer memory for storing the received signals of both receiving antennas;
A depth calculation circuit for calculating a depth based on at least one received signal;
An identification circuit that compares the two received signals and identifies the embedded object of the received signal based on both the moving direction distance and depth of the carriage,
A correction circuit for correcting the carriage movement direction deviation of both received signals of the identified buried object from the depth value;
A combined display circuit for combining the corrected received signals;
An underground exploration device characterized by comprising: In the underground exploration device according to claim 1,
An underground exploration apparatus characterized in that the combined display circuit combines the corrected received signals with a sum operation. In the underground exploration device according to claim 1,
An underground exploration apparatus characterized in that the combined display circuit combines the corrected reception signals with a difference calculation. In the underground exploration device according to claim 1,
An underground exploration apparatus characterized in that the combined display circuit combines the corrected reception signals by product operation.