Ultra-wideband low-altitude electromagnetic integrated measurement device and method

Abstract

The invention discloses an ultra-wideband low-altitude electromagnetic integrated measuring device, which comprises a short-offset electromagnetic method measuring device, a ground penetrating radar measuring device, an infrared imaging measuring device and a power supply, wherein the short-offset electromagnetic method measuring device, the ground penetrating radar measuring device and the infrared imaging measuring device are arranged in a horizontal plate; the power supply supplies power to the short-offset electromagnetic method measuring device, the ground penetrating radar measuring device and the infrared imaging measuring device; wherein the short-offset electromagnetic method measuring device is used for measuring electromagnetic primary field data and electromagnetic secondary field data; the ground penetrating radar measuring device is used for measuring related parameters of electromagnetic reflected waves; the infrared imaging measurement device is used for imaging a measurement area by using infrared rays; the invention further discloses an ultra-wideband low-altitude electromagnetic integrated measurement method. The ultra-wideband low-altitude electromagnetic integrated measurement method can realize measurement, inversion and imaging of various parameters.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic integrated measurement, in particular to an ultra-wideband low-altitude electromagnetic integrated measurement device and method. Background Art

[0002] At present, the commonly used electromagnetic exploration methods based on low-altitude measurement include short-offset electromagnetic method and ground-penetrating radar. The short-offset electromagnetic method is based on the principle of electromagnetic induction. It transmits electromagnetic waves and receives reflected signals. By calculating and analyzing the amplitude and phase of the electromagnetic field, information about the conductivity of the underground medium can be obtained. The ground-penetrating radar ensures that the spacing between the transmitting antenna and the receiving antenna remains unchanged, and moves along the survey line at a certain measurement spacing to obtain the electromagnetic reflection wave record of the entire survey line. In addition, infrared imagers can measure infrared electromagnetic waves, that is, they use the difference in infrared radiation energy between the target and the background received by the infrared detector to detect and identify the target. The above three technologies all use a single device to measure relevant parameters.

[0003] In terms of data processing, the construction of joint constraint methods is generally based on physical property correlation and structural coupling. Physical property correlation constraints can be used when different physical property parameters have a rock physics coupling relationship. When the physical property parameter changes have no obvious directionality, the cross-gradient constraint effect is limited. Many scholars have proposed joint inversion of different parameters. For example, Yi Ke proposed a two-dimensional RMT and DC joint inversion of resistivity and dielectric constant in the working frequency band of 10kHz-1 MHz; Li Jie studied the joint inversion of resistivity and thermal conductivity of magnetotelluric method and low-temperature field. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an ultra-wideband low-altitude electromagnetic integrated measurement device and method, which can realize the measurement, inversion and imaging of multiple parameters.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an ultra-wideband low-altitude electromagnetic integrated measurement device, including a short-offset electromagnetic measurement device, a ground-penetrating radar measurement device, an infrared imaging measurement device and a power supply for the short-offset electromagnetic measurement device, the ground-penetrating radar measurement device and the infrared imaging measurement device, which are arranged in a horizontal plate; wherein the short-offset electromagnetic measurement device is used to measure electromagnetic primary and secondary field data; the ground-penetrating radar measurement device is used to measure electromagnetic reflection wave related parameters; and the infrared imaging measurement device is used to use infrared rays to image the measurement area.

[0006] As a further improvement of the present invention, a slide rail for adjusting the offset distance of the short offset distance electromagnetic measurement device is also provided in the horizontal plate.

[0007] As a further improvement of the present invention, counterweights for maintaining the balance of the electromagnetic integrated measuring device are also provided on both sides and the middle of the horizontal plate.

[0008] As a further improvement of the present invention, the power supply is externally placed on a horizontal plate.

[0009] The present invention also provides an ultra-wideband low-altitude electromagnetic integrated measurement method, comprising the following steps:

[0010] Step 1: Use a drone to drag the ultra-wideband low-altitude electromagnetic integrated measurement device as described above through a connecting cable; measure short-offset electromagnetic data, ground-penetrating radar data, and infrared imaging data according to the survey area and survey tasks, and transmit the data to a terminal for data processing;

[0011] Step 2, measuring data is transmitted to the terminal: for short-offset electromagnetic data measurement, the transmitting coil excites a primary electromagnetic field with different frequencies and a certain intensity, and the receiving coil simultaneously receives the superimposed primary field data and secondary field data; for ground penetrating radar data measurement, the transmitting antenna excites an electromagnetic wave signal of a frequency, and the receiving antenna receives the reflected electromagnetic wave data; for infrared detection, the power signal radiated from the surface is directly measured or converted into an electrical signal to calculate the surface temperature, and at the same time, several temperature measuring points are set in different areas of the surface to measure the temperature within a certain range underground;

[0012] Step 3, establish a multi-parameter processing module: perform joint inversion on the three parameters of resistivity, dielectric constant and temperature at the same time, add the temperature model as known information to the inversion of the other two parameters, and solve the objective function until the inversion fitting error is met or the maximum number of iterations is reached;

[0013] Step 4: Establish a multi-parameter image fusion module: select two types of parameter data within a certain range of underground depth in the same measurement interval for image fusion, realize the pairwise combination of multiple parameters, and realize the fusion of images of different depths within an extremely shallow depth range.

[0014] As a further improvement of the present invention, the step 3 specifically comprises the following steps:

[0015] Step 3.1: Establish temperature model:

[0016] ① According to soil heterogeneity and actual needs, the sampling area is divided into irregular random sampling or regular sampling, and several temperature measurement points are set to measure the temperature parameters within a certain range from the surface to the underground, and a function T(z) = T0e is established for the temperature change of a single sampling point with depth. -αz , where T0 is the surface temperature and α is the attenuation factor;

[0017] ② Use different interpolation methods for the attenuation factor according to the sampling method: For random sampling, find the expected value c of the attenuation factor of all known sampling points, and then use the simple Kriging interpolation method to find the surface position (x i ,y i ) is the attenuation factor α(x i ,y i ), whose formula is where λ k is able to satisfy the surface position (x i ,y i ) with the smallest difference between the estimated value and the true value;

[0018] For regular sampling, select the surface location (x i ,y i ) The four nearest sampling points P n (n=1,2,3,4) is obtained by using the spatial area inverse weighted method, that is, connecting the four selected sampling points to form a rectangle, drawing two perpendicular lines through the calculation points, respectively perpendicular to the sides of the rectangle, and dividing the area W of four different sizes by the rectangle and the perpendicular lines n (n=1,2,3,4), calculate Get the surface position (x i ,y i ) is the attenuation factor α(x i ,y i );

[0019] ③ The infrared imaging measurement device in the integrated device measures the surface temperature parameters of a large area in order to obtain the surface position (x i ,y i ) surface temperature T0(x i ,y i );

[0020] ④ Place the same position (x i ,y i ) is the attenuation factor α(x i ,y i ) and the surface temperature T0(x i ,y i ) combination, we get the function of the temperature at that location changing with depth T(z) = T0e -αz ; The temperature parameters at different depths underground at that location are calculated; After multiple calculations are performed in a certain order, multiple groups of one-dimensional discrete temperature parameters with regular arrangement are obtained, and after combining them and performing linear interpolation calculations, a three-dimensional temperature model required for joint inversion is obtained;

[0021] Step 3.2, input the resistivity and dielectric constant measured by short offset electromagnetic method and ground penetrating radar and their corresponding initial models; then, input the constructed temperature model;

[0022] Step 3.3, based on the separate inversion of resistivity and dielectric constant, add the cross-gradient terms of resistivity and dielectric constant, the cross-gradient terms of resistivity and temperature, and the cross-gradient terms of dielectric constant and temperature to solve the joint inversion iterative calculation, and its objective function is:

[0023]

[0024] in, are the measured short-offset electromagnetic data and ground-penetrating radar data, F1 and F2 are forward operators, and is the covariance matrix of the data and the model, m1, m2 and m3 are the resistivity model, dielectric constant model and temperature model, m 0,1 、m 0,2 is the a priori model of resistance and dielectric constant, λ1 and λ2 are regularization factors, μ1, μ2 and μ3 are cross-gradient term weights;

[0025] Step 3.4, calculate the inversion fitting difference of the current resistivity model and dielectric constant model, and judge whether it meets the termination condition: if it meets the condition, save the current resistivity model and dielectric constant model and stop the iteration, and jump to step 3.5; if it does not meet the condition, continue the iteration, and the temperature model always remains unchanged as the constraint information in the inversion;

[0026] Step 3.5: Stop the inversion and output the calculated resistivity model and dielectric constant model.

[0027] The present invention can measure three parameters simultaneously or asynchronously, and realizes a multi-parameter (resistivity, dielectric constant and temperature) joint inversion algorithm of electromagnetic method, ground penetrating radar and infrared imaging.

[0028] Multi-parameter acquisition: The present invention sets the UAV flight route, measurement device combination, and measurement method according to the survey area; Multi-parameter processing: The present invention processes multiple parameters. Set appropriate inversion parameters based on the number and type of data to be processed. The joint inversion process is that three parameters are carried out simultaneously, and the temperature model is added as known information to the inversion of the other two parameters to solve the objective function until the inversion fit difference is met or the maximum number of iterations is reached; Multi-parameter image fusion: Multi-parameter image fusion is performed by combining multi-parameter data of different depths in the same area and extremely shallow depth range to explain multi-parameter abnormal characteristics.

[0029] The beneficial effects of the present invention are:

[0030] The present invention combines the measurement of resistivity, dielectric constant and temperature, realizes the measurement of large-area multi-parameters, avoids interference due to environmental conditions, machines and humans, is beneficial to setting the corresponding acquisition parameter types and acquisition methods according to actual survey work, and greatly saves measurement time and expenses; realizes a multi-parameter (resistivity, dielectric constant and temperature) joint inversion algorithm based on electromagnetic method, ground penetrating radar and infrared imaging and a multi-parameter image extremely shallow depth fusion method, and visualization of the processing results is helpful to explain the multi-parameter abnormal characteristics of the study area. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The measurement schematic diagram provided by the present invention;

[0032] Figure 2 A top view of the integrated device provided by the present invention;

[0033] Figure 3 A side view of the integrated device provided by the present invention;

[0034] Figure 4 Schematic diagram of the measurement principle provided by the present invention;

[0035] Figure 5 The random temperature measurement point distribution diagram provided by the present invention;

[0036] Figure 6 The equidistant temperature measurement point distribution diagram provided by the present invention;

[0037] Figure 7 Schematic diagram of the principle of the area inverse weighting method provided by the present invention;

[0038] Figure 8 Schematic diagram of fusion of surface temperature and apparent resistivity image provided by the present invention;

[0039] Fig. 9 Schematic diagram of the fusion of surface temperature and dielectric constant images provided by the present invention;

[0040] Fig.10 Schematic diagram of fusion of surface temperature and inversion resistivity image provided by the present invention;

[0041] Fig.11 Schematic diagram of the fusion of surface temperature and inverted dielectric constant image provided by the present invention. DETAILED DESCRIPTION

[0042] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] Example

[0044] In order to achieve multi-parameter measurement, processing and imaging, this embodiment performs the following steps:

[0045] Step 1: Follow the steps below Figure 1 The measurement diagram shown in the figure is used to measure data, that is, a drone drags the integrated device of the present invention through a connecting cable. The integrated device diagram is shown in Figure 2 and Figure 3 As shown, the contents and their functions are as follows:

[0046] 1: Short offset electromagnetic measurement device: measure electromagnetic primary and secondary field data;

[0047] 2: Slide rail: can adjust the offset distance of the short offset electromagnetic measurement device;

[0048] 3: Ground penetrating radar measurement device: measures parameters related to electromagnetic reflection waves;

[0049] 4: Infrared imaging measurement device: uses infrared rays to image the measurement area;

[0050] 5: Power supply: to supply power to devices 1, 3, and 4 (externally located on a horizontal plate for easy replacement);

[0051] 6: Counterweight: maintain the balance of the entire integrated device;

[0052] 7: Signal shielding layer: prevents each measuring device from being affected by adjacent devices.

[0053] This device integrates short-offset electromagnetic method, ground-penetrating radar and infrared imaging, and can collect single parameters as well as synchronous or asynchronous multi-parameters. The above method is used for data measurement, that is, a drone drags the integrated device of the present invention through a connecting cable. According to the survey area and survey task, short-offset electromagnetic method data, ground-penetrating radar data and infrared imaging data are measured, and the data are transmitted to the terminal for data processing.

[0054] Step 2: Transmit the measured data to the terminal. The measurement principle is as follows Figure 4 As shown in the figure, for short-offset electromagnetic data measurement, the transmitting coil excites a primary electromagnetic field with different frequencies and a certain intensity, and the receiving coil can simultaneously receive the superimposed primary field data and secondary field data. For ground penetrating radar data measurement, the transmitting antenna excites an electromagnetic wave signal of a frequency, and the receiving antenna receives the reflected electromagnetic wave data. For infrared detection, the power signal radiated by the surface is directly measured or converted into an electrical signal to calculate the surface temperature. At the same time, several temperature measurement points are set in different areas of the surface to measure the temperature within 1m underground.

[0055] Step 3: Establish a multi-parameter processing module:

[0056] The three parameters of resistivity, dielectric constant and temperature are jointly inverted at the same time. The temperature model is added as known information to the inversion of the other two parameters. The following objective function is solved until the inversion fitting error is met or the maximum number of iterations is reached. The detailed process is as follows:

[0057] (1) Establish a temperature model.

[0058] ① According to soil heterogeneity and actual needs, the sampling area is divided into irregular random sampling (such as Figure 5 ), or regular sampling (as shown Figure 6 Set up several temperature measurement points to measure the temperature parameters within the range of 1m from the surface to the underground, and establish a function T(z)=T0e where the temperature of a single sampling point changes with depth. -αz , where T0 is the surface temperature and α is the attenuation factor.

[0059] ② Use different interpolation methods for the attenuation factor according to the sampling method. For random sampling, find the expected value c of the attenuation factor of all known sampling points, and then use the simple Kriging interpolation method to find the surface position (x i ,y i ) is the attenuation factor α(x i ,y i ), whose formula is where λ k is able to satisfy the surface position (x i ,y i ) with the smallest difference between the estimated value and the true value;

[0060] For regular sampling, select the surface location (x i ,y i ) The four nearest sampling points P n (n=1,2,3,4) is obtained by using the spatial area inverse weighted method, that is, connecting the four selected sampling points to form a rectangle, drawing two perpendicular lines through the calculation points, respectively perpendicular to the sides of the rectangle, and dividing the area W of four different sizes by the rectangle and the perpendicular lines n (n=1,2,3,4)(e.g. Figure 7 As shown), calculate Get the surface position (x i ,y i ) is the attenuation factor α(x i ,y i ).

[0061] ③ The infrared imaging measurement device in the integrated device measures the surface temperature parameters of a large area in order to obtain the surface position (x i ,y i ) surface temperature T0(x i ,y i).

[0062] ④ Place the same position (x i ,y i ) is the attenuation factor α(x i ,y i ) and the surface temperature T0(x i ,y i ) combination, we get the function of the temperature at that location changing with depth T(z) = T0e -αz . Thus, the temperature parameters at different depths underground can be calculated. After performing the above calculations multiple times in a certain order, multiple groups of regularly arranged one-dimensional discrete temperature parameters can be obtained. After combining them and performing linear interpolation calculations, the three-dimensional temperature model required for joint inversion can be obtained.

[0063] (2) Input the resistivity and dielectric constant data measured by short offset electromagnetic method and ground penetrating radar and their corresponding initial models. Then, input the temperature model constructed in step (1).

[0064] (3) Based on the traditional single inversion of resistivity and dielectric constant, the cross-gradient terms of resistivity and dielectric constant, the cross-gradient terms of resistivity and temperature, and the cross-gradient terms of dielectric constant and temperature are added to solve the joint inversion iterative calculation. The objective function is:

[0065]

[0066] in, are the measured short-offset electromagnetic data and ground-penetrating radar data, F1 and F2 are forward operators, and is the covariance matrix of the data and the model, m1, m2 and m3 are the resistivity model, dielectric constant model and temperature model, m 0,1 、m 0,2 are the resistance prior model and the dielectric constant prior model, λ1 and λ2 are regularization factors, and μ1, μ2 and μ3 are the cross-gradient term weights.

[0067] (4) Calculate the inversion fitting difference of the current resistivity model and dielectric constant model to determine whether the termination condition is met: if so, save the current resistivity model and dielectric constant model and stop the iteration, and jump to step (5); if not, continue the iteration, and the temperature model remains unchanged as constraint information in the inversion.

[0068] (5) Stop inversion and output the calculated resistivity model and dielectric constant model.

[0069] Step 4: Establish a multi-parameter image fusion module:

[0070] This embodiment can select two types of parameter data with an underground depth within 1 m in the same measurement interval for image fusion, which can not only realize the pairwise combination of multiple parameters, but also realize the fusion of images at different depths.

[0071] The surface temperature obtained by infrared imaging is fused with the resistivity at a depth of 0.5 meters obtained by short-offset electromagnetic method. Figure 8 .

[0072] The surface temperature obtained by infrared imaging and the dielectric constant at a depth of 0.5 meters obtained by ground penetrating radar are fused. Fig. 9 .

[0073] Furthermore, for the joint inversion results, the present invention can still use image fusion to visualize the data, which helps to make the interpretation intuitive and characterization.

[0074] The surface temperature obtained by infrared imaging and the resistivity and dielectric constant of the underground depth of 0.5 meters obtained by joint inversion are fused separately as follows: Fig.10 and Fig.11 shown.

[0075] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An ultra-wideband low-altitude electromagnetic integrated measurement device, It is characterized in that It includes a short-offset electromagnetic measurement device, a ground-penetrating radar measurement device, an infrared imaging measurement device and a power supply for the short-offset electromagnetic measurement device, the ground-penetrating radar measurement device and the infrared imaging measurement device, which are arranged in a horizontal plate; wherein the short-offset electromagnetic measurement device is used to measure electromagnetic primary and secondary field data; the ground-penetrating radar measurement device is used to measure parameters related to electromagnetic reflection waves; and the infrared imaging measurement device is used to image the measurement area using infrared rays.

2. The ultra-wideband low-altitude electromagnetic integrated measurement device according to claim 1, It is characterized in that The horizontal plate is also provided with a slide rail for adjusting the offset distance of the short offset distance electromagnetic measurement device.

3. The ultra-wideband low-altitude electromagnetic integrated measurement device according to claim 1, It is characterized in that Counterweights for maintaining the balance of the electromagnetic integrated measuring device are also provided on both sides and the middle of the horizontal plate.

4. The ultra-wideband low-altitude electromagnetic integrated measurement device according to claim 1, It is characterized in that The power supply is externally mounted on a pre-leveling board.

5. An ultra-wideband low-altitude electromagnetic integrated measurement method, It is characterized in that The following steps are involved: Step 1: Use a drone to drag the ultra-wideband low-altitude electromagnetic integrated measurement device as described in any one of claims 1 to 4 through a connecting cable; measure short-offset electromagnetic data, ground penetrating radar data and infrared imaging data according to the survey area and survey tasks, and transmit the data to a terminal for data processing; Step 2, measuring data is transmitted to the terminal: for short-offset electromagnetic data measurement, the transmitting coil excites a primary electromagnetic field with different frequencies and a certain intensity, and the receiving coil simultaneously receives the superimposed primary field data and secondary field data; for ground penetrating radar data measurement, the transmitting antenna excites an electromagnetic wave signal of a frequency, and the receiving antenna receives the reflected electromagnetic wave data; for infrared detection, the power signal radiated from the surface is directly measured or converted into an electrical signal to calculate the surface temperature, and at the same time, several temperature measuring points are set in different areas of the surface to measure the temperature within a certain range underground; Step 3, establish a multi-parameter processing module: perform joint inversion on the three parameters of resistivity, dielectric constant and temperature at the same time, add the temperature model as known information to the inversion of the other two parameters, and solve the objective function until the inversion fitting error is met or the maximum number of iterations is reached; Step 4: Establish a multi-parameter image fusion module: select two types of parameter data within a certain range of underground depth in the same measurement interval for image fusion, realize the pairwise combination of multiple parameters, and realize the fusion of images of different depths within an extremely shallow depth range.

6. The ultra-wideband low-altitude electromagnetic integrated measurement method according to claim 5, It is characterized in that The step 3 specifically comprises the following steps: Step 3.1: Establish temperature model: ① According to soil heterogeneity and actual needs, the sampling area is divided into irregular random sampling or regular sampling, and several temperature measurement points are set to measure the temperature parameters within a certain range from the surface to the underground, and a function T(z) = T is established for the temperature change of a single sampling point with depth. 0 e -αz , where T 0 is the surface temperature, α is the attenuation factor; ② Use different interpolation methods for the attenuation factor according to the sampling method: For random sampling, find the expected value c of the attenuation factor of all known sampling points, and then use the simple Kriging interpolation method to find the surface position (x i ,y i ) is the attenuation factor α(x i ,y i ), whose formula is where λ k is able to satisfy the surface position (x i ,y i ) with the smallest difference between the estimated value and the true value; For regular sampling, select the surface location (x i ,y i ) The four nearest sampling points P n (n=1,2,3,4) is obtained by using the spatial area inverse weighted method, that is, connecting the four selected sampling points to form a rectangle, drawing two perpendicular lines through the calculation points, respectively perpendicular to the sides of the rectangle, and dividing the area W of four different sizes by the rectangle and the perpendicular lines n (n=1,2,3,4), calculate Get the surface position (x i ,y i ) is the attenuation factor α(x i ,y i ); ③ The infrared imaging measurement device in the integrated device measures the surface temperature parameters of a large area in order to obtain the surface position (x i ,y i ) surface temperature T 0 (x i ,y i ); ④ Place the same position (x i ,y i ) is the attenuation factor α(x i ,y i ) and the surface temperature T 0 (x i ,y i ) combination, we get the function of the temperature at that location changing with depth T(z) = T 0 e -αz ; The temperature parameters at different depths underground at that location are calculated; After multiple calculations are performed in a certain order, multiple groups of one-dimensional discrete temperature parameters with regular arrangement are obtained, and after combining them and performing linear interpolation calculations, a three-dimensional temperature model required for joint inversion is obtained; Step 3.2, input the resistivity and dielectric constant measured by short offset electromagnetic method and ground penetrating radar and their corresponding initial models; then, input the constructed temperature model; Step 3.3, based on the separate inversion of resistivity and dielectric constant, add the cross-gradient terms of resistivity and dielectric constant, the cross-gradient terms of resistivity and temperature, and the cross-gradient terms of dielectric constant and temperature to solve the joint inversion iterative calculation, and its objective function is: in, The short-offset electromagnetic data and ground-penetrating radar data are measured. 1 、F 2 is the forward operator, and is the covariance matrix between the data and the model, m 1 、m 2 and m 3 is the resistivity model, dielectric constant model and temperature model, m 0,1 、m 0,2 is the a priori model of resistance and dielectric constant, λ 1 , 2 is the regularization factor, μ 1 , μ 2 and μ 3 is the cross gradient term weight; Step 3.4, calculate the inversion fitting difference of the current resistivity model and dielectric constant model, and judge whether it meets the termination condition: if it meets the condition, save the current resistivity model and dielectric constant model and stop the iteration, and jump to step 3.5; if it does not meet the condition, continue the iteration, and the temperature model always remains unchanged as the constraint information in the inversion; Step 3.5: Stop the inversion and output the calculated resistivity model and dielectric constant model.

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