Ground penetrating radar and millimeter wave radar integrated coupling imaging device and method

Abstract

The invention discloses a ground penetrating radar and millimeter wave radar integrated coupling imaging device and method, and belongs to the technical field of earth detection and information. Performing ray tracing on the earth surface three-dimensional model by adopting a processor to synthesize an air direct wave model channel of the earth surface structure; adopting an adaptive filtering method to adaptively subtract air direct waves caused by structures above the ground surface from the ground penetrating radar data; and finally, after migration imaging is carried out on the ground penetrating radar data for suppressing the air direct waves, an underground medium model is constructed and accurately matched with the millimeter wave radar ground surface three-dimensional model, and construction of a ground surface and underground integrated three-dimensional model is achieved. According to the ground penetrating radar and millimeter wave radar integrated coupling imaging device and method, the anti-interference problem of the ground penetrating radar is solved, ground surface and underground integrated coupling imaging is achieved, and the device and method have high practical value and innovativeness.

Description

Technical Field

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

[0002] In addition to propagating underground, electromagnetic waves emitted by ground-penetrating radar will inevitably propagate into the air above the surface. Therefore, in complex environments such as urban overhead high-voltage lines, viaducts, and electric poles, the interference of direct air waves reflected by surface structures and the effective transmission waves reflected by underground geological bodies will be superimposed on each other, causing serious troubles for the accurate imaging of underground geological bodies by ground-penetrating radar. To address this problem, existing ground-penetrating radars mostly use shielded antennas to reduce the impact of direct air waves, but the shielding cavity will increase the size and mass of the antenna, and may also cause obvious ringing interference to the ground-penetrating radar data and affect the detection depth to a certain extent. In particular, it is very difficult to use shielding for low-frequency antennas with a large detection depth below 50Mhz. Currently, commercial low-frequency ground-penetrating radar antennas mostly use non-shielding methods, resulting in the interference of direct air waves caused by surface structures in complex environments, which is an important factor affecting the imaging effect of ground-penetrating radar underground media at greater depths. Therefore, exploring a non-shielded ground-penetrating radar method and equipment that can adapt to harsh environments such as the ground is a very practical content. Summary of the invention

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

[0004] To achieve the above object, the present invention provides a ground penetrating radar and millimeter wave radar integrated coupling imaging device, comprising: RTK module and millimeter radar module are used to perform three-dimensional scanning and imaging of surface structures within the detection site; Processor, used to obtain high-precision three-dimensional discrete point cloud information and three-dimensional models of surface objects in the detection site, calculate the propagation time of the electromagnetic signal of the ground penetrating radar, synthesize the air direct wave model channel in the ground penetrating radar acquisition process, and suppress the air direct wave noise of the actual ground penetrating radar data; A memory for storing three-dimensional models and various parameters of surface structures; The processor is also connected to a transmitting antenna and a receiving antenna.

[0005] A ground penetrating radar and millimeter wave radar integrated coupling imaging method, comprising the following steps: S1. Extraction of 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 (including the spatial position and reflectivity of the object) 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 ground penetrating radar transmitting antenna at the surface acquisition position 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; 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; 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 imaged by the millimeter-wave radar in S2 with the three-dimensional model of the underground medium imaged by the ground-penetrating radar in S6 as the final surface-underground integrated coupled imaging three-dimensional model.

[0006] Preferably, in S4, a 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 objects.

[0007] Preferably, the adaptive filtering methods adopted by S5 include L1 / L2 norm adaptive matching subtraction method, artificial intelligence, pattern recognition, matched filtering, linear least squares, single-channel and multi-channel Wiener filtering.

[0008] Preferably, in S7, high-precision positioning information of the shared RTK module is used to accurately match the surface and underground models.

[0009] Therefore, the present invention adopts the above-mentioned ground penetrating radar and millimeter wave radar integrated coupling imaging device and method, which has the following beneficial effects: (1) On the one hand, the millimeter-wave radar used to construct the near-surface structure model helps the ground-penetrating radar suppress the near-surface air direct wave noise; on the other hand, the full combination of ground-penetrating radar and millimeter-wave radar realizes the integrated coupling imaging of the surface and underground, which is helpful for geological disaster detection and geological survey. (2) The combination of software and hardware solves the problem of poor suppression of air direct wave interference by existing ground penetrating radar, which is highly practical and innovative in practice.

[0010] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of the structure of a device according to an embodiment of the present invention; Figure 2 It is a flowchart of the overall process of an embodiment of the present invention; Figure 3 The millimeter wave radar surface imaging diagram of an embodiment of the present invention; Figure 4 The following are comparison diagrams of the ground penetrating radar profiles before and after suppressing the interference of the direct air wave according to the embodiment of the present invention; wherein (a) is the ground penetrating radar profile before suppressing the interference of the direct air wave, and (b) is the ground penetrating radar profile after suppressing the interference of the direct air wave; Figure 5 This is a three-dimensional model of surface and underground integrated coupled imaging according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] See also Figure 1 , a ground penetrating radar and millimeter wave radar integrated coupling imaging device, comprising: RTK module and millimeter radar module are used to perform three-dimensional scanning and imaging of surface objects within the detection site; Processor, used to obtain high-precision three-dimensional discrete point cloud information and three-dimensional models of surface objects in the detection site, calculate the propagation time of the electromagnetic signal of the ground penetrating radar, synthesize the air direct wave model channel in the ground penetrating radar acquisition process, and suppress the air direct wave noise of the actual ground penetrating radar data; A memory for storing three-dimensional models and various parameters of surface structures; The processor is also connected to a transmitting antenna and a receiving antenna.

[0014] like Figure 2 , a ground penetrating radar and millimeter wave radar integrated coupling imaging method, comprising the following steps: S1. Extracting Ground Penetrating Radar Wavelet Using Metal Plate Reflection Method Specifically, the ground penetrating radar is first used to collect data from an upright metal plate to obtain the ground penetrating radar total reflection data volume. Then, the sub-wavelength of the ground penetrating radar total reflection data volume is extracted according to a certain time window. , and stored in the memory.

[0015] S2. Use the RTK module and millimeter wave radar module to perform three-dimensional scanning and imaging of the surface objects in the detection site, especially focusing on scanning and imaging large metal objects such as high-voltage lines and towers that are seriously interfered with by the electromagnetic waves of the ground penetrating radar. Use the processor to obtain high-precision three-dimensional discrete point cloud information (including the spatial position and reflectivity of the object) of the surface objects in the detection site, and construct a three-dimensional model of the surface structure (such as Figure 3 ) and stored in the memory.

[0016] from Figure 3 It can be clearly seen that there are two overhead high-voltage lines and steel houses on the surface. These artificial structures on the surface will cause significant interference to the ground penetrating radar signal.

[0017] 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 ground penetrating radar transmitting antenna at the surface acquisition position when it is reflected by the surface structure and reaches the receiving antenna .

[0018] S4, the processor calculates the propagation time t and reflectivity GPR wavelet extracted from S1 The convolution synthesis of the air direct wave model during the ground penetrating radar acquisition process.

[0019] The convolution method is used to synthesize the ground penetrating radar air direct wave model channel, which can be 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 objects.

[0020] S5. The processor adopts 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.

[0021] The adaptive filtering methods 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 of the actual ground penetrating radar data, and the expression formula is as follows: ; In the formula, M It is the synthetic air direct wave interference model channel data; d is the original ground penetrating radar data; f is the matched filter operator; Q 1 is the objective function.

[0022] The GPR profile before and after the suppression of the air direct wave interference is shown in the figure below: Figure 4 As shown. Figure 4 It can be seen that the GPR profile before the suppression of the air direct wave interference is seriously disturbed by the overhead high-voltage line on the surface, and the lower rock-soil layer interface and pipeline anomalies are seriously affected. When the air direct wave interference is suppressed by the method of this embodiment, the quality of the GPR profile data is significantly improved, and the deep rock-soil interface and pipeline diffraction waves can be better distinguished.

[0023] S6. The processor uses filtering, gain and Kirchhoff migration imaging to suppress the noise of the ground penetrating radar data 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. The bandpass filter parameter is [10 90] and the Kirchhoff migration imaging speed is 0.09m / ns.

[0024] The spatial position information of the RTK module is synchronously transmitted to the ground penetrating radar as the positioning information of the data collected by the ground penetrating radar to facilitate the registration of the surface and underground imaging model in step S7.

[0025] S7, accurately matching the three-dimensional model of the surface structure imaged by the millimeter-wave radar in S2 with the three-dimensional model of the underground medium obtained by the ground-penetrating radar in S6 according to the high-precision positioning information of the RTK module as the final surface-underground integrated coupled imaging three-dimensional model (such as Figure 5 ).

[0026] Therefore, the present invention adopts the above-mentioned ground penetrating radar and millimeter wave radar integrated coupling imaging device and method, realizes accurate modeling of near-surface structures through millimeter wave radar, and then uses ray tracing technology to accurately synthesize the air direct wave model for the near-surface structures detected by the ground penetrating radar. Subsequently, an adaptive filter is used to suppress the air direct wave of the ground penetrating radar collected data 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 precise 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 realizes the integrated coupling imaging of the surface and underground, and has high practical value and innovation.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A ground penetrating radar and millimeter wave radar integrated coupling imaging device, characterized in that: include: RTK module and millimeter wave radar module are used to perform three-dimensional scanning and imaging of surface structures within the detection site; A processor is used to obtain high-precision three-dimensional discrete point cloud information and three-dimensional models of surface structures in the detection site, calculate the propagation time of the electromagnetic signal of the ground penetrating radar, synthesize the air direct wave model channel in the ground penetrating radar acquisition process, and suppress the air direct wave noise of the actual ground penetrating radar data; A memory for storing three-dimensional models and various parameters of surface structures; The processor is also connected to a transmitting antenna and a receiving antenna.

2. A ground penetrating radar and millimeter wave radar integrated coupling imaging method, characterized in that: The following steps are involved: 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; 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; 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.

3. The method for integrated coupling imaging of ground penetrating radar and millimeter wave radar according to claim 2, characterized in that: In S4, 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 objects.

4. The method for integrated coupling imaging of ground penetrating radar and millimeter wave radar according to claim 3, 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.

5. The method for integrated coupling imaging of ground penetrating radar and millimeter wave radar according to claim 4, 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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