An integrated coupling imaging device and method for ground penetrating radar and millimeter wave radar

Abstract

The present invention discloses a ground penetrating radar and millimeter wave radar integrated coupling imaging device and method, belonging to the field of earth exploration and information technology. The device constructs a three-dimensional model above the ground surface using a millimeter wave radar, and then, a processor performs ray tracing on the three-dimensional ground surface model to synthesize an air direct wave model trace of surface structures; an adaptive filtering method is used to adaptively subtract the air direct wave caused by structures above the ground surface from the ground penetrating radar data; finally, the ground penetrating radar data with the air direct wave suppressed is subjected to migration imaging to construct an underground medium model and accurately match it with the three-dimensional ground surface model of the millimeter wave radar, realizing the construction of an integrated three-dimensional model of the ground surface and underground. The ground penetrating radar and millimeter wave radar integrated coupling imaging device and method provided by the present invention solve the anti-interference problem of the ground penetrating radar while realizing the integrated coupling imaging of the ground surface and underground, and have high practical value and innovation.

Description

Technical Field

[0001] The present invention relates to the field of geodetection and information technology, and particularly to a device and method for integrated coupling imaging of a ground penetrating radar and a millimeter wave radar. Background Art

[0002] In addition to propagating underground, the electromagnetic waves emitted by a ground penetrating radar will inevitably also propagate into the air above the ground surface. Therefore, in complex environments such as urban overhead high-voltage lines, viaducts, and utility poles, the direct air wave reflected by surface structures in the ground penetrating radar will interfere with the effective transmitted wave reflected back by underground geological bodies, bringing serious troubles to the accurate imaging of underground geological bodies by the ground penetrating radar. To address this problem, existing ground penetrating radars mostly adopt the method of shielding antennas to reduce the influence of direct air waves, but the shielding cavity will increase the size and mass of the antenna, and at the same time may bring obvious ringing interference to the ground penetrating radar data and affect the detection depth to a certain extent. Especially for low-frequency antennas with a large detection depth below 50Mhz, it is very difficult to use shielding. Currently, most commercial low-frequency ground penetrating radar antennas adopt non-shielding methods, and the interference of direct air waves caused by surface structures in complex environments is an important factor affecting the imaging effect of underground media by the ground penetrating radar at a large depth. Therefore, exploring a non-shielding ground penetrating radar method and equipment that can adapt to such harsh environments is a very practical content. Summary of the Invention

[0003] The purpose of the present invention is to provide a device and method for integrated coupling imaging of a ground penetrating radar and a millimeter wave radar to solve the problems existing in the background art.

[0004] To achieve the above purpose, the present invention provides an integrated coupling imaging device for a ground penetrating radar and a millimeter wave radar, including:

[0005] An RTK module and a millimeter radar module for three-dimensional scanning and imaging of surface structures in the detection site;

[0006] A processor for obtaining high-precision three-dimensional discrete point cloud information and three-dimensional models of surface objects in the detection site, calculating the propagation time of the electromagnetic signal of the ground penetrating radar, synthesizing the direct air wave model trace during the acquisition process of the ground penetrating radar, and suppressing the direct air wave noise in the actual ground penetrating radar data;

[0007] A memory for storing the three-dimensional model of surface structures and various parameters;

[0008] The processor is also connected to a transmitting antenna and a receiving antenna.

[0009] An integrated coupling imaging method for a ground penetrating radar and a millimeter wave radar includes the following steps:

[0010] S1. Extract the ground penetrating radar (GPR) wavelet using the correlation coefficient method, high-order cumulant method, or metal plate reflection method , and store it in the memory;

[0011] S2. Use the RTK module and millimeter-wave radar module to perform three-dimensional scanning and imaging of surface objects in the detection site. The processor obtains high-precision three-dimensional discrete point cloud information of surface objects in the detection site (including the spatial position and reflectivity of the objects), and constructs a three-dimensional model of the surface structure and stores it in the memory;

[0012] S3. Using the three-dimensional model of the surface structure in the memory, the processor calculates the propagation time t and reflectivity when the electromagnetic wave emitted by the GPR transmitting antenna at the surface acquisition position reaches the receiving antenna after being reflected by the surface structure in the way of ray tracing ;

[0013] S4. The processor performs convolution synthesis on the air direct wave model trace in the GPR acquisition process according to the propagation time t, reflectivity and the GPR wavelet extracted in S1 ;

[0014] S5. The processor uses the method of adaptive filtering to suppress the air direct wave noise of the actual GPR data with the air direct wave model trace as the input model trace data;

[0015] S6. The processor performs filtering, gain, and Kirchhoff migration imaging on the GPR data after noise suppression to achieve precise imaging of the geological bodies below the surface in the detection site and obtain a three-dimensional model of the underground medium;

[0016] S7. Precisely match the three-dimensional model of the surface structure obtained by millimeter-wave radar imaging in S2 and the three-dimensional model of the GPR underground medium obtained in S6 as the final three-dimensional model of the integrated surface and underground coupled imaging.

[0017] Preferably, in S4, the method of convolution is used to synthesize the air direct wave model trace of the GPR, which is expressed by the following formula:

[0018] ;

[0019] In the formula, is the synthesized air direct wave model trace; is the GPR wavelet; is the reflectivity of the surface object.

[0020] Preferably, the adaptive filtering method used in S5 includes L1 / L2 norm adaptive matching subtraction, artificial intelligence, pattern recognition, matched filtering, linear least squares, single-channel and multi-channel Wiener filtering.

[0021] Preferably, in S7, the high-precision positioning information of the shared RTK module is used for accurate matching of the surface and underground models.

[0022] Therefore, the present invention adopts the above-mentioned integrated imaging device and method of ground penetrating radar and millimeter wave radar, and has the following beneficial effects:

[0023] (1) On the one hand, the millimeter wave radar adopted constructs a near-surface structure model, which helps the ground penetrating radar to suppress the near-surface air direct wave noise; on the other hand, fully combining the ground penetrating radar and the millimeter wave radar realizes integrated imaging of the surface and underground, which is helpful for geological disaster detection, geological exploration, etc.

[0024] (2) The method combining software and hardware solves the problem that the existing ground penetrating radar has poor effect in suppressing air direct wave interference, and has strong practicability and innovation in practice.

[0025] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the device structure of the embodiment of the present invention;

[0027] Figure 2 is the overall flow block diagram of the embodiment of the present invention;

[0028] Figure 3 is the surface imaging diagram of the millimeter wave radar of the embodiment of the present invention;

[0029] Figure 4 is the comparison diagram of the ground penetrating radar cross-sections before and after suppressing the air direct wave interference of the embodiment of the present invention; wherein, (a) is the ground penetrating radar cross-section diagram before suppressing the air direct wave interference, and (b) is the ground penetrating radar cross-section diagram after suppressing the air direct wave interference;

[0030] Figure 5 is the three-dimensional model of the integrated imaging of the surface and underground of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention to be protected, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0032] Please refer to Figure 1 , an integrated imaging device of ground penetrating radar and millimeter wave radar, comprising:

[0033] An RTK module and a millimeter-wave radar module for three-dimensional scanning and imaging of surface objects within a detection site;

[0034] A processor for obtaining high-precision three-dimensional discrete point cloud information and three-dimensional models of surface objects within the detection site, calculating the propagation time of ground-penetrating radar electromagnetic signals, synthesizing the air direct wave model trace during the ground-penetrating radar acquisition process, and suppressing air direct wave noise in actual ground-penetrating radar data;

[0035] A memory for storing three-dimensional models and various parameters of surface structures;

[0036] The processor is also connected to a transmitting antenna and a receiving antenna.

[0037] Such as Figure 2 , a method for integrated coupling imaging of a ground-penetrating radar and a millimeter-wave radar, comprising the following steps:

[0038] S1. Extract the ground-penetrating radar wavelet using the metal plate reflection method . Specifically, first use the ground-penetrating radar to collect data from an erected metal plate to obtain the ground-penetrating radar full reflection data volume. Then extract the wavelet of the ground-penetrating radar full reflection data volume according to a certain time window , and store it in the memory.

[0039] S2. Use the RTK module and the millimeter-wave radar module to perform three-dimensional scanning and imaging of surface objects within the detection site, especially focusing on scanning and imaging large metal objects such as high-voltage lines and iron towers that cause severe interference to the ground-penetrating radar electromagnetic waves. Use the processor to obtain high-precision three-dimensional discrete point cloud information (including the spatial position and reflectivity of the objects) of surface objects within the detection site, and construct a three-dimensional model of the surface structure (such as Figure 3 ) and store it in the memory.

[0040] From Figure 3 , it can be clearly seen that there are two overhead high-voltage lines and a steel plate house on the surface, and these surface artificial structures will cause significant interference to the ground-penetrating radar signals.

[0041] S3. Using the three-dimensional model of the surface structure in the memory, the processor calculates the propagation time t and reflectivity when the electromagnetic wave emitted by the ground-penetrating radar transmitting antenna at the surface acquisition position reaches the receiving antenna after being reflected by the surface structure by means of ray tracing .

[0042] S4. The processor performs convolution synthesis of the air direct wave model trace during the ground-penetrating radar acquisition process according to the propagation time t, the reflectivity and the ground-penetrating radar wavelet extracted in S1 .

[0043] The method of synthesizing the air direct wave model trace of a ground penetrating radar using convolution can be expressed by the following formula:

[0044] ;

[0045] In the formula, is the synthesized air direct wave model trace; is the ground penetrating radar wavelet; is the reflectivity of surface objects.

[0046] S5. The processor uses the method of adaptive filtering to take the air direct wave model trace as the input model trace data to suppress the air direct wave noise in the actual ground penetrating radar data.

[0047] The methods of adaptive filtering include L1 / L2 norm adaptive matching subtraction, artificial intelligence, pattern recognition, matched filtering, linear least squares, single-channel and multi-channel Wiener filtering. The adaptive filtering method used in this embodiment is L1 norm adaptive subtraction to suppress the air direct wave noise in the actual ground penetrating radar data. The expression formula is as follows:

[0048] ;

[0049] In the formula, M is the data of the synthesized air direct wave interference model trace; d is the original ground penetrating radar data; f is the matched filtering operator; Q 1 is the objective function.

[0050] The ground penetrating radar profiles before and after the suppression of air direct wave interference are as Figure 4 shown. It can be seen from Figure 4 that the ground penetrating radar profile before the suppression of air direct wave interference is seriously interfered by the overhead high-voltage lines on the surface, and the lower rock and soil stratification interface and pipeline anomalies are seriously affected. When the air direct wave interference is suppressed by the method of this embodiment, the data quality of the ground penetrating radar profile is significantly improved, and the rock and soil interface and pipeline diffraction wave in the middle and deep parts can be better distinguished.

[0051] S6. The processor uses filtering, gain, and Kirchhoff migration imaging on the ground penetrating radar data after noise suppression to achieve accurate imaging of the geological bodies below the surface in the detection site and obtain a three-dimensional model of the underground medium. Among them, the band-pass filtering parameters are [10 90], and the Kirchhoff migration imaging velocity is 0.09 m / ns.

[0052] The spatial position information of the RTK module is synchronously transmitted to the ground penetrating radar as the positioning information for the data collected by the ground penetrating radar to facilitate the registration of the surface and underground imaging models in step S7.

[0053] S7. The three-dimensional model of the surface structures imaged by the millimeter-wave radar in S2 and the three-dimensional model of the underground medium of the ground penetrating radar obtained in S6 are accurately matched according to the high-precision positioning information of the RTK module to serve as the final integrated three-dimensional imaging model of the surface and underground (such as Figure 5 ).

[0054] Therefore, the present invention adopts the above-mentioned integrated coupling imaging device and method of a ground penetrating radar and a millimeter-wave radar. The millimeter-wave radar is used to accurately model the near-surface structures, and then the ray tracing technology is used to accurately synthesize the air direct wave model for the air direct wave interference generated by the near-surface structures during the detection of the ground penetrating radar. Subsequently, an adaptive filter is used to suppress the air direct wave in the data collected by the ground penetrating radar to obtain a high-quality three-dimensional model of the underground medium. Finally, the integrated coupling imaging of the surface and underground is realized through the accurate matching of the millimeter-wave radar surface model and the ground penetrating radar underground model. While solving the anti-interference problem of the ground penetrating radar, the device and method achieve the integrated coupling imaging of the surface and underground, and have high practical value and innovation.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A ground penetrating radar and millimeter wave radar integrated coupling imaging method, characterized in that: include: S1. Extract ground penetrating radar wavelets using correlation coefficient method, high-order cumulant method or metal plate reflection method , and store it in a memory; S2. Use the RTK module and the millimeter wave radar module to perform three-dimensional scanning and imaging of the surface objects in the detection site, use the processor to obtain high-precision three-dimensional discrete point cloud information of the surface objects in the detection site, and construct a three-dimensional model of the surface structure and store it in the memory; S3. Using the three-dimensional model of the surface structure in the memory, the processor uses ray tracing to calculate the propagation time t and reflectivity of the electromagnetic wave emitted by the transmitting antenna of the ground-penetrating radar at the detection site when it is reflected by the surface structure and reaches the receiving antenna. ; S4, the processor calculates the propagation time t and reflectivity GPR wavelet extracted from S1 Perform convolution to synthesize the air direct wave model during the ground penetrating radar acquisition process; The convolution method is used to synthesize the ground penetrating radar air direct wave model channel, which is expressed by the following formula: ； In the formula, is the synthetic air direct wave model channel; is the ground penetrating radar wavelet; is the reflectivity of the surface object; S5, the processor uses an adaptive filtering method to use the air direct wave model channel as input model channel data to suppress the air direct wave noise of the actual ground penetrating radar data; The adaptive filtering method used is L1 norm adaptive subtraction to suppress the air direct wave noise of the actual ground penetrating radar data. The expression formula is as follows: ； In the formula, M It is the synthetic air direct wave interference model channel data; is the original ground penetrating radar data; is the matched filter operator; is the objective function; S6. The processor uses filtering, gain and Kirchhoff shift imaging on the ground penetrating radar data after noise suppression to achieve accurate imaging of the geological body below the surface of the detection site and obtain a three-dimensional model of the underground medium; S7, accurately matching the three-dimensional model of the surface structure in S2 with the three-dimensional model of the underground medium obtained by the ground penetrating radar in S6 as the final surface and underground integrated coupled imaging three-dimensional model.

2. The method for integrated coupling imaging of ground penetrating radar and millimeter wave radar according to claim 1, characterized in that: The adaptive filtering methods used by S5 include L1 / L2 norm adaptive matched subtraction, artificial intelligence, pattern recognition, matched filtering, linear least squares, single-channel and multi-channel Wiener filtering.

3. The method for integrated coupling imaging of ground penetrating radar and millimeter wave radar according to claim 2, characterized in that: S7 uses the high-precision positioning information of the RTK module to accurately match the surface and underground models.

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