Unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system and detection method

Abstract

Provided are a UAV array aerial multi-component electric field and magnetic field cooperative detection system and method, the detection system comprising: a UAV array, a transmitting unit, multiple receiving units, and a ground auxiliary unit; the UAV array comprising a master UAV and multiple slave UAVs; the transmitting unit being configured to transmit a primary electromagnetic field pulse; the transmitting unit comprising a loop source transmitting device, the loop source transmitting device comprising a current transmitter, a transmitting coil, and a compensation coil; the multiple receiving units being respectively mounted on the master UAV and the slave UAVs and configured to collect electromagnetic data after the primary electromagnetic field pulse acts on a region to be detected, the electromagnetic data comprising horizontal component electric field signals and three-component magnetic field signals; each receiving unit comprising a capacitive electric field sensor, a three-component coil magnetic field sensor, and an electromagnetic data receiver; and the ground auxiliary unit being configured to control the collection of the horizontal component electric field signals and the three-component magnetic field signals, and to process the electromagnetic data to obtain underground space electrical property information of a detection region.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of electromagnetic detection technology, in particular to a UAV arrayed aerial multi-component electric field and magnetic field cooperative detection system and method. BACKGROUND

[0002] The transient electromagnetic method (TEM) is a geophysical method for obtaining the resistivity distribution of underground media by analyzing and studying the secondary field response characteristics of induced eddy currents generated by underground media under the excitation of external field sources. The basic principle is to use a non-grounded loop or grounded line source to transmit a primary pulse magnetic field, and to use a coil or grounded electrode to detect the secondary induced eddy current field in the underground medium during the primary pulse magnetic field interval. By measuring the secondary field variation with time in each time period after power-off, the geoelectric characteristics at different depths can be obtained. The transient electromagnetic method can be mainly divided into three modes of full-airborne, semi-airborne and ground detection according to the instrument mounting platform. Among them, the full-airborne transient electromagnetic method adopts a helicopter or unmanned aerial vehicle to carry an electromagnetic field transmitting and receiving integrated device, uses a loop source to transmit a primary pulse magnetic field, excites the secondary electromagnetic field response of underground abnormal electrical bodies, and the measured magnetic field response is sensitive to low-resistance targets, which is mainly used for metal mineral, underground water and other target detection.

[0003] At present, the airborne electromagnetic detection technology has been developed and applied relatively maturely. This system places the entire loop source transmitting and receiving device in the air for detection with the help of unmanned aerial vehicles or helicopters, and has the advantages of flexibility, low labor cost and high detection efficiency. However, the traditional airborne electromagnetic detection technology only detects single-component magnetic field signals and cannot realize air electric field measurement, so that the ground electric field measurement system cannot be expanded to the unmanned aerial vehicle platform and still needs manpower for ground station operation. Until recently, breakthroughs have been made in the hardware technology of electric field sensors, making stable measurement of air electric field components possible. On the other hand, the existing airborne electromagnetic detection system is composed of a single flight platform carrying a transmitting source and a receiving sensor. With the rapid development of software and hardware technology, the unmanned, miniaturized, integrated and arrayed geophysical exploration system has become an inevitable trend of future development. However, the traditional single-machine flight operation mode has limited information of abnormal electromagnetic response of the underground electrical structure excited by the transmitting source due to the fixed relative position of the transmitting and receiving, which is difficult to fully obtain the electromagnetic response characteristics related to the underground electrical structure, and faces serious multi-solution problems for complex three-dimensional underground space exploration. SUMMARY

[0004] Therefore, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides a UAV arrayed aerial multi-component electric field and magnetic field cooperative detection system and a detection method, aiming to simultaneously obtain multi-view and multi-parameter electromagnetic response information of underground electric medium by combining a UAV array platform and an electric field and magnetic field multi-parameter cooperative detection system, and improve the detection accuracy of complex underground space three-dimensional target bodies.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present disclosure is as follows:

[0006] In an embodiment of one aspect of the present disclosure, a UAV arrayed aerial multi-component electric field and magnetic field cooperative detection system is provided, comprising: a UAV array, a transmitting unit, a plurality of receiving units, and a ground auxiliary unit; wherein the UAV array comprises a master UAV and a plurality of slave UAVs; the transmitting unit is mounted under the master UAV and is configured to transmit a primary electromagnetic field pulse; the transmitting unit comprises a loop source transmitting device, the loop source transmitting device comprising a current transmitter, a transmitting coil, and a compensation coil; the plurality of receiving units are respectively mounted under the master UAV and the slave UAVs and are configured to collect electromagnetic data after the primary electromagnetic field pulse acts on a to-be-detected region, the electromagnetic data comprising a horizontal component electric field signal and a three-component magnetic field signal; each receiving unit comprises a capacitive electric field sensor, a three-component coil magnetic field sensor, and an electromagnetic data receiver; the ground auxiliary unit is configured to control the collection of the horizontal component electric field signal and the three-component magnetic field signal and to process the electromagnetic data to obtain underground space electric information of a detection region.

[0007] According to the embodiment of the present disclosure, the capacitive electric field sensor comprises an x-component electric field sensor and a y-component electric field sensor. The x-component electric field sensor is configured to point in a direction parallel to the travel direction of the survey line for measuring the x-component electric field; and the y-component electric field sensor is configured to point in a direction perpendicular to the travel direction of the survey line for measuring the y-component electric field.

[0008] According to the embodiment of the present disclosure, the capacitive electric field sensor adopts a non-contact measurement principle to convert an unknown to-be-detected electric field into a voltage across a capacitor; the capacitive electric field sensor is arranged at the front and back ends of the connecting framework in the travel direction of the survey line, and comprises an upper electrode plate, a lower electrode plate, a measurement circuit board, and an insulating column: the upper electrode plate and the lower electrode plate are arranged in parallel to form a parallel-plate capacitor, and the materials, areas, and thicknesses of the upper electrode plate and the lower electrode plate are the same; the input ends of the measurement circuit board are respectively connected to the upper electrode plate and the lower electrode plate, and the measurement circuit board comprises a sampling capacitor; the insulating column is configured to connect and fix the upper electrode plate, the lower electrode plate, and the measurement circuit board; the capacitive electric field sensor is placed in an electric field space, and the charges generated on the surfaces of the upper electrode plate and the lower electrode plate form a voltage across the sampling capacitor, and the voltage across the sampling capacitor is measured to obtain electric field data.

[0009] According to the embodiment of the present disclosure, the three-component coil magnetic field sensor comprises an x-component magnetic field sensor, a y-component magnetic field sensor, and a z-component magnetic field sensor. The x-component magnetic field sensor is configured as a semicircle, and the normal of the plane where the x-component magnetic field sensor is located points to the x direction, and is used for measuring the x-component magnetic field; the y-component magnetic field sensor is configured as a semicircle, and the normal of the plane where the y-component magnetic field sensor is located points to the y direction, and is used for measuring the y-component magnetic field; and the z-component magnetic field sensor is configured as a circle, and the normal of the plane where the z-component magnetic field sensor is located points to the z direction, and is used for measuring the z-component magnetic field.

[0010] According to the embodiment of the present disclosure, the transmitting coil, the compensation coil, and the z-component magnetic field sensor are arranged in the same plane, and the radius ratio of the transmitting coil and the compensation coil is equal to the turn ratio of the transmitting coil and the compensation coil.

[0011] According to the embodiment of the present disclosure, the electromagnetic data receiver comprises a signal conditioning module, a signal acquisition module, a storage module, and a transmission module. The signal conditioning module is configured to filter and amplify the received horizontal component electric field signal and three-component magnetic field signal; the signal acquisition module comprises an analog-to-digital conversion circuit and is configured to sample the signal processed by the signal conditioning module; the storage module is configured to store the multi-component electric field data and magnetic field data sampled by the signal acquisition module; and the transmission module is configured to transmit the acquired multi-component electric field data and magnetic field data to an auxiliary unit.

[0012] The ground auxiliary unit comprises a control device, a monitoring device, and a data processing device. The control device is configured to send a working control instruction in cooperation with the detection system; the monitoring device is configured to monitor the system parameter state, the multi-component electric field data, the magnetic field data, and the position information of the cooperative detection system in real time; and the data processing device is configured to process the electromagnetic data to obtain the underground space electrical property information of the detection area.

[0013] According to the embodiment of the present disclosure, the cooperative detection system further comprises a positioning device, a radar altimeter, and a power supply device. The positioning device is used to position the unmanned aerial vehicle array in real time to obtain the longitude and latitude information of each unmanned aerial vehicle in the unmanned aerial vehicle array; the radar altimeter is used to measure the flight height of the unmanned aerial vehicle array; and the power supply device is used to supply power to the cooperative detection system.

[0014] In another aspect of the embodiments of the present disclosure, a detection method based on the cooperative detection system of any one of the above is provided, comprising: S1, assembling and debugging the cooperative detection system; S2, setting the detection system parameters and the unmanned aerial vehicle array flight parameters according to the field conditions and the user detection requirements; S3, exciting a primary electromagnetic field pulse signal through the center primary field compensation technology according to the received control instruction; S4, collecting the horizontal component electric field signal and the three-component magnetic field signal data; and S5, pre-processing the obtained horizontal component electric field signal and the three-component magnetic field signal data, and obtaining the underground space electrical property information of the detection area through the electric field and magnetic field data joint inversion method.

[0015] According to the embodiments of the present disclosure, the detection system system parameters include the emission current amplitude, the emission current shape, the emission current frequency of the current transmitter, and the electromagnetic data receiver sampling rate; and the unmanned aerial vehicle array flight parameters include the unmanned aerial vehicle array formation mode, the flight height, the flight speed, and the flight route.

[0016] According to the embodiments of the present disclosure, obtaining the underground space electrical property information of the detection area through the electric field and magnetic field data joint inversion method comprises: S51, setting the initial resistivity model and the model parameters; S52, calculating the magnetic field response error and the electric field response error by using the magnetic field and electric field response forward modeling to respectively calculate the magnetic field response and the electric field response of the initial resistivity model and the errors between the calculated magnetic field response and electric field response and the detected magnetic field response and electric field response; S53, constructing the Jacobian matrix of the magnetic field and electric field data inversion by using the resistivity model, and respectively calculating the model update amount of the magnetic field data inversion and the model update amount of the electric field data inversion by using the magnetic field response error and the electric field response error; S54, adding the model update amount and the model parameters to obtain the updated resistivity model; S55, determining whether the fitting error of the forward electric field and magnetic field response data of the updated resistivity model is less than a set threshold value, and sequentially determining whether to iterate; and S56, terminating when the fitting error is less than the set threshold value, and iterating the number of times when the fitting error is greater than the set threshold value, and entering the S53 step, at this time, the resistivity model updated by the electric field inversion is calculated by the model parameters obtained in the magnetic field inversion in the last iteration, and the resistivity model updated by the magnetic field inversion is calculated by the model parameters obtained in the electric field inversion in the last iteration, until the iteration is terminated when the fitting error is less than the set threshold value. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 A working scene schematic diagram of the unmanned aerial vehicle array type aviation multi-component electric field and magnetic field cooperative detection system according to the embodiments of the present disclosure is schematically shown.

[0019] Figure 2a Fig. 2 schematically shows a structural schematic diagram of an aerial receiving unit of a slave unmanned aerial vehicle of the unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system according to an embodiment of the present disclosure.

[0020] Figure 2b Fig. 2 schematically shows a structural schematic diagram of an aerial receiving unit of a slave unmanned aerial vehicle of the unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system according to an embodiment of the present disclosure.

[0021] Figure 3 Fig. 4 schematically shows a center primary field compensation technology diagram of the unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system according to an embodiment of the present disclosure.

[0022] Figure 4 Fig. 5 schematically shows an internal structure schematic diagram of a capacitive electric field sensor of the unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system according to an embodiment of the present disclosure.

[0023] Figure 5 Fig. 6 schematically shows a flowchart of a detection method based on the unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system according to an embodiment of the present disclosure.

[0024] Figure 6 Fig. 7 schematically shows an electromagnetic response diagram after processing by the center primary field compensation technology according to an embodiment of the present disclosure.

[0025] Figure 7a Fig. 8 schematically shows a flowchart of an electric field and magnetic field data joint inversion method according to an embodiment of the present disclosure.

[0026] Figure 7b Fig. 9 schematically shows a flowchart architecture diagram of the electric field and magnetic field data joint inversion method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The present disclosure provides an unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system and a detection method, which realizes simultaneous receiving of multi-azimuth, multi-component electric field and magnetic field data in the air, solves the problem of single electromagnetic response acquisition parameter and limited information quantity in the single-machine detection mode of the traditional airborne electromagnetic method detection technology, and improves the detection precision in the underground space detection field.

[0028] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, further detailed descriptions will be given below in combination with specific embodiments and with reference to the drawings.

[0029] In the embodiments of the present disclosure, an unmanned aerial vehicle arrayed aerial multi-component electric field and magnetic field cooperative detection system is provided, which combines Figure 1 , Figure 2a , Figure 2bAs shown, the cooperative detection system comprises a UAV array, a transmitting unit, a plurality of receiving units, and a ground auxiliary unit; wherein:

[0030] The UAV array comprises a master UAV and a plurality of slave UAVs;

[0031] The transmitting unit is mounted under the master UAV and is configured to transmit a primary electromagnetic field pulse; the transmitting unit comprises a loop source transmitting device, which comprises a current transmitter, a transmitting coil, and a compensation coil;

[0032] The plurality of receiving units are respectively mounted under the master UAV and the slave UAVs and are configured to collect electromagnetic data after the primary electromagnetic field pulse acts on the region to be detected, the electromagnetic data comprising horizontal component electric field signals and three-component magnetic field signals; each receiving unit comprises a capacitive electric field sensor, a three-component coil magnetic field sensor, and an electromagnetic data receiver;

[0033] The ground auxiliary unit is configured to control the collection of the horizontal component electric field signals and the three-component magnetic field signals and to process the electromagnetic data to obtain underground space electrical property information of the detection region.

[0034] The master UAV platform simultaneously mounts the transmitting unit and the receiving unit, the number of the slave UAV platforms is 3-5, and only the receiving unit is mounted, thereby forming different transmitting and receiving distances with the master UAV platform. The compensation coil is arranged between the transmitting coil and the three-component coil magnetic field sensor, the current flowing through the compensation coil and the transmitting coil is of the same size but opposite directions, so as to eliminate the electromagnetic field interference of the transmitting coil on the three-component coil magnetic field sensor, the three-component coil magnetic field sensor is used to acquire x, y, and z component magnetic field data, and the capacitive electric field sensor is used to acquire horizontal x and y component electric field data.

[0035] According to the embodiment of the present disclosure, the master UAV and the slave UAV platforms are the same type of UAV, the pod under the master UAV platform simultaneously comprises the transmitting unit, the receiving unit, and a connecting device, the pod under the slave UAV platform only comprises the receiving unit and the connecting device, and the slave UAV platform keeps synchronous and same direction flight with the UAV platform, the master UAV platform and the slave UAV platform can be at different heights, and the relative distance between them ranges from 30 m to 150 m, so as to ensure the detection precision. The connecting device can comprise a signal cable, a rope composite cable, and a connecting skeleton, for example, and is used to realize the fixation or connection between the master UAV, the slave UAV, and the corresponding transmitting unit and receiving unit, and between the transmitting unit and the receiving unit.

[0036] According to the embodiment of the present disclosure, the transmitting coil, the compensation coil and the z-component coil of the three-component coil magnetic field sensor are arranged on the same horizontal plane and share the same center, and are connected and fixed by the rope composite cable and suspended below the unmanned aerial vehicle. The transmitting coil and the compensation coil are both circular. In addition, the transmitting coil and the compensation coil can be bundled in a carbon fiber pipe, for example, to maintain the shape of the coil and ensure safety of power supply.

[0037] According to the embodiment of the present disclosure, the current transmitter can generate continuous current waveforms with different amplitudes, different frequencies and different shapes according to user requirements, and load them into the transmitting coil to form an air loop source to radiate electromagnetic field outward. In addition, the current transmitter is powered by the unmanned aerial vehicle.

[0038] According to the embodiment of the present disclosure, the capacitive electric field sensor includes x-component electric field and y-component electric field sensors, which are respectively directed to x and y directions to measure x-component and y-component electric fields in the air. The performance parameters of the x-component electric field sensor and the y-component electric field sensor are the same, and they are connected by a connecting frame at the front and rear ends of the transmitting coil.

[0039] According to the embodiment of the present disclosure, the three-component coil magnetic field sensor includes x-component magnetic field sensor, y-component magnetic field sensor and z-component magnetic field sensor, which are respectively used to measure x-component, y-component and z-component magnetic fields and are orthogonally arranged in a hemispherical protective cover.

[0040] According to the embodiment of the present disclosure, the electromagnetic data receiver includes a signal conditioning module, a signal acquisition module, a storage module and a transmission module. The signal conditioning module is used to filter and amplify the received multi-component electric field and magnetic field data. The signal acquisition module is an analog-to-digital converter circuit used to sample the conditioned signal. The storage module is used to store the acquired multi-component electric field and magnetic field data. The transmission module is used to remotely transmit the acquired multi-component electric field and magnetic field data to the ground auxiliary unit.

[0041] According to the embodiment of the present disclosure, the unmanned aerial vehicle aerial multi-component electric field and magnetic field cooperative detection system further comprises a positioning device for real-time positioning of the unmanned aerial vehicle array system to obtain the latitude and longitude information of the unmanned aerial vehicle array system; a radar altimeter for measuring the flight height of the unmanned aerial vehicle array system; a power supply device for supplying power to the cooperative detection system, such as for supplying power to the unmanned aerial vehicle array system and for supplying power to the transmitting unit; the ground auxiliary unit comprises a control device for sending start, temporary, continue, and terminate work instructions to the system; a monitoring device for real-time monitoring of system state (such as detection system parameter state), electric field, magnetic field data, and system position, height, and other information. A data processing device is configured to process electromagnetic data to obtain underground space electrical property information of the detection area. The system parameters of the detection system may include, for example, the emission current amplitude, emission current shape, emission current frequency of the current transmitter, and the sampling rate of the electromagnetic data receiver; and the unmanned aerial vehicle array flight parameters include the unmanned aerial vehicle array formation mode, flight height, flight speed, and flight route.

[0042] In another aspect of the embodiment of the present disclosure, a detection method based on the unmanned aerial vehicle array aerial multi-component electric field and magnetic field cooperative detection system is provided, as shown in Figure 5 The detection method comprises the following steps:

[0043] S1: Assembling and debugging the cooperative detection system;

[0044] S2: Setting the detection system parameters and the unmanned aerial vehicle array flight parameters according to the site conditions and user detection requirements of the detection area;

[0045] S3: According to the received control instructions, exciting a primary electromagnetic field pulse signal through the center primary field compensation technology;

[0046] S4: Collecting the horizontal component electric field signal and three-component magnetic field signal data; and

[0047] S5: Preprocessing the obtained horizontal component electric field signal and three-component magnetic field signal data, and obtaining the underground space electrical property information of the detection area through the electric field and magnetic field data joint inversion method.

[0048] According to the embodiment of the present disclosure, the electric field and magnetic field data joint inversion method for obtaining the underground space electrical property information of the detection area comprises Figure 5 and Figure 7a , Figure 7b

[0049] S51: Setting an initial resistivity model and model parameters;

[0050] ​S52: calculate the magnetic field response error and the electric field response error by using the magnetic field and electric field response forward model to calculate the magnetic field response and the electric field response of the initial resistivity model and the error between the detected magnetic field response and the electric field response;

[0051] S53: construct the Jacobian matrix of the magnetic field and electric field data inversion by using the resistivity model, and calculate the model update amount of the magnetic field data inversion and the model update amount of the electric field data inversion by using the magnetic field response error and the electric field response error, respectively;

[0052] S54: add the model update amount and the model parameter to obtain the updated resistivity model;

[0053] S55: determine whether the forward electric field and magnetic field response data fitting error of the updated resistivity model is less than a set threshold, and determine whether to perform iteration in turn; and

[0054] S56: terminate when the fitting error is less than the set threshold, and when the fitting error is greater than the set threshold, increase the iteration number by one and enter the step S53, wherein the resistivity model updated by the electric field inversion is calculated by using the model parameter obtained by the magnetic field inversion in the last iteration, and the resistivity model updated by the magnetic field inversion is calculated by using the model parameter obtained by the electric field inversion in the last iteration, until the fitting error is less than the set threshold to terminate the iteration.

[0055] According to the embodiments of the present disclosure, in combination with Figure 7a and Figure 7b In step S56, it is determined whether the forward electric field and magnetic field data fitting error of the updated resistivity model is less than a set threshold; if yes, the algorithm terminates; if no, the iteration number n is increased by one and the step S53 is entered, wherein the resistivity model updated by the electric field inversion is calculated by using the model parameter obtained by the magnetic field inversion in the last iteration, and the resistivity model updated by the magnetic field inversion is calculated by using the model parameter obtained by the electric field inversion in the last iteration. Enter the steps S54 and S55 until the iteration termination condition is met.

[0056] More specifically, first, the debugging airborne electromagnetic detection system device is assembled, flight safety test of the unmanned aerial vehicle array is carried out, and flight safety of the unmanned aerial vehicle aerial multi-component electric field and magnetic field cooperative detection system during work is ensured; according to the field situation of the survey area and the user detection requirement, system parameters and flight parameters of the aerial unmanned aerial vehicle multi-component electric field and magnetic field cooperative detection system are set, wherein the system parameters may for example include a transmission current amplitude of the current transmitter, a transmission current shape, a transmission current frequency and a sampling rate of the receiving unit, and the flight parameters may for example include a formation of the unmanned aerial vehicle array, a flight height, a flight speed and a flight route; the system starts to work according to the set parameters, when the system starts to work, the pulsed electromagnetic field is transmitted by the under-slung pod return line source transmission device of the main unmanned aerial vehicle, and the main unmanned aerial vehicle and the slave unmanned aerial vehicle receive unit cooperatively and continuously collect horizontal component electric field and three-component magnetic field data; the obtained multi-azimuth detection horizontal component electric field and three-component magnetic field data are preprocessed, and the underground space electrical information of the detection area is obtained through the electric field and magnetic field data joint inversion method.

[0057] According to the embodiments of the present disclosure, with the help of the unmanned aerial vehicle array system and the capacitive electric field sensor, multi-azimuth, multi-component electric field data of the airborne electrical source transient electromagnetic system can be measured very conveniently; by setting the compensation coil in the transmission coil, the first field electromagnetic interference of the transmission coil on the magnetic field sensor is reduced, relatively pure multi-azimuth, multi-component magnetic field data can be obtained, and thus the underground space electrical information obtained through analysis is more accurate; the multi-azimuth angle, multi-component electric field and magnetic field data can be obtained simultaneously through once air operation by using the unmanned aerial vehicle array collection mode; combined with the multi-azimuth, multi-component electric field and magnetic field data joint inversion method, the multi-solution of single electromagnetic field parameter inversion can be effectively reduced, and the system detection information obtained through fusion is more comprehensive and accurate.

[0058] According to the embodiments of the present disclosure, as Figure 1 shown, the unmanned aerial vehicle array type aerial multi-component electric field and magnetic field cooperative detection system of the embodiments of the present disclosure includes an unmanned aerial vehicle array, a transmission unit, a receiving unit and a ground auxiliary unit, and simultaneously has multi-azimuth collection of horizontal component electric field (E X and E Y ) and three-component magnetic field signal (dB X / dt, dB Y / dt and dB ZThe ability of the unmanned aerial vehicle arrayed airborne multi-component electric field and magnetic field cooperative detection system to radiate electromagnetic field to the outside by inputting pulse current to the airborne loop source, and to cause the underground structure to generate induced eddy current, and the ability of the multiple receiving units suspended on the unmanned aerial vehicle array to acquire the electric field and magnetic field signals generated by the induced eddy current from multiple directions, can realize high-precision detection of underground resistivity. Specifically, the unmanned aerial vehicle arrayed airborne multi-component electric field and magnetic field cooperative detection system can acquire the resistivity information of the underground space by analyzing and processing the received electric field and magnetic field signal data.

[0059] According to the embodiments of the present disclosure, as shown in Figure 2a and Figure 2b , the unmanned aerial vehicles of the master unmanned aerial vehicle and the slave unmanned aerial vehicle are the flight platforms of the system, which are used to carry the airborne loop source transmitting device and the receiving device, and enable the detection system to fly in the air according to the pre-planned detection path. The unmanned aerial vehicles can be remotely controlled by the staff, and the specific structure and performance parameters are not limited here. As shown in Figure 2a , the master unmanned aerial vehicle airborne loop source subsystem includes a transmitting coil, a compensation coil, a three-component magnetic field sensor, a horizontal component electric field sensor, and a current transmitter and a data receiver. The current transmitter and the data receiver are integrated at the lower part of the unmanned aerial vehicle and are powered by the unmanned aerial vehicle alone; the transmitting coil, the compensation coil, the three-component magnetic field sensor, and the electric field sensor are suspended below the unmanned aerial vehicle by the main cable. As shown in Figure 2b , the slave unmanned aerial vehicle receiving subsystem only includes a three-component magnetic field sensor, a horizontal component electric field sensor, and a data receiver, and does not include a transmitting source. The data receiver is integrated at the lower part of the unmanned aerial vehicle and is powered by the unmanned aerial vehicle alone, and the three-component magnetic field sensor and the horizontal component electric field sensor are suspended below the unmanned aerial vehicle by the main cable.

[0060] According to the embodiments of the present disclosure, the current transmitter described above can generate current pulse waveforms of different amplitudes, different frequencies, and different shapes according to user needs, and load them into the transmitting coil and the compensation coil. The data receiver described above is a multi-channel sampling receiver, which can perform multi-channel synchronous sampling and storage of the electric field and magnetic field response data according to the set sampling rate.

[0061] According to the embodiments of the present disclosure, as shown in Figure 2a , the transmitting coil and the compensation coil carried by the master unmanned aerial vehicle can be wound by multiple turns of copper wire, the winding directions of the two are opposite, and the turn ratio of the transmitting coil to the compensation coil is equal to the radius ratio of the transmitting coil to the compensation coil. The transmitting coil and the compensation coil are both bundled in a circular glass fiber tube, and the compensation coil is inside the transmitting coil, and the two are fixed by the cable connection.

[0062] According to the embodiment of the present disclosure, three-component magnetic field data can be acquired through the three-component coil magnetic field sensor at the center of the transmitting coil; the compensation coil between the transmitting coil and the coil magnetic field sensor can reduce the first field electromagnetic interference of the transmitting coil on the coil magnetic field sensor, and further make the acquired underground space electrical property information more accurate. In addition, the three-component coil magnetic field sensor is installed in the hemispherical protective cover, and the compensation coil and the transmitting coil are indirectly connected through the composite cable, avoiding direct connection to make the sensor device jolt under stress.

[0063] According to the embodiment of the present disclosure, the electric field sensor includes an x-component electric field sensor and a y-component electric field sensor. The x-component electric field sensor and the y-component electric field sensor are respectively directed to the x and y directions, and are used to measure the x-component and y-component electric fields. The capacitive electric field sensor adopts a non-contact measurement principle, and can very conveniently measure the air electric field component without grounding. The performance parameters of all the electric field sensors are the same, and the electric field sensors are arranged at both ends of the transmitting coil through the connecting framework, and each electric field sensor is 0.3-0.5 m away from the edge of the transmitting coil.

[0064] According to the embodiment of the present disclosure, as shown in Figure 3 , the compensation coil is arranged on the inner side of the transmitting coil, and the coil winding modes of the transmitting coil and the compensation coil make the current direction I T of the transmitting coil opposite to the current direction I B of the compensation coil, and an equal-amplitude opposite-direction first magnetic field is generated in the area of the central receiving coil, thereby better offsetting the strong first field in the secondary electromagnetic field signal received by the three-component magnetic sensor, realizing weak coupling between the transmitting coil and the receiving coil, acquiring a pure secondary field signal, and reducing the electromagnetic field interference of the transmitting device on the receiving device.

[0065] According to the embodiment of the present disclosure, as shown in Figure 4 , the internal structure of the capacitive electric field sensor (which can be simply referred to as a capacitor or a flat capacitor) includes two symmetrical upper and lower plates, a measurement circuit and an insulating column. The upper and lower plates are two copper plates with the same area and thickness, forming a parallel plate capacitor; the measurement circuit is used to convert the measurement of the unknown electric field into the measurement of the voltage between the known capacitors; and the insulating column is used to connect the upper and lower plates and the measurement circuit board. The capacitive electric field sensor measurement principle is as follows: the sensor is placed in the electric field space, the surface charge Q of the plate is proportional to the electric field E between the two plates, and satisfies Q=C1EH, where C1 is the parallel plate capacitor capacity, and H is the relative height between the two plates. The upper and lower plates and the measurement circuit board are connected by wires, and the core element of the measurement circuit board is a sampling capacitor C2. The charge on the parallel plate will form a micro power supply voltage U e =Q / C2 on both ends of the sampling capacitor. Therefore, by measuring the voltage between the sampling capacitors, the electric field E=C2U eC1H. When measuring the sampling capacitor voltage, a differential input circuit is used, which can suppress common-mode noise and improve sensor sensitivity.

[0066] According to the embodiments of the present disclosure, as shown in Figure 6 After the first magnetic field compensation, the pure quadratic magnetic field receiving signal of the underground target can be obtained, which is beneficial to reduce the dynamic range of the receiving unit and improve the quality of the early electromagnetic response signal. Further, the receiving device can obtain relatively pure electromagnetic data, and a relatively clear underground target electrical property detection image can be obtained by processing the electromagnetic data.

[0067] Thus far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that the implementation manners not shown or described in the drawings or the specification are known to those skilled in the art, and are not described in detail. In addition, the definitions of the elements and methods described above are not limited to the various specific structures, shapes or manners mentioned in the embodiments, and can be simply changed or replaced by those skilled in the art.

[0068] According to the above description, those skilled in the art should have a clear understanding of the unmanned aerial vehicle array type aerial multi-component electric field and magnetic field cooperative detection system and detection method of the present disclosure.

[0069] In summary, the present disclosure provides an unmanned aerial vehicle array type aerial multi-component electric field and magnetic field cooperative detection system and detection method, which uses a light and small unmanned aerial vehicle as a flight carrying platform, has the advantages of low flight cost, flexibility and high safety; the present disclosure breaks through the traditional single-aircraft working mode and uses an unmanned aerial vehicle array formation detection method to realize multi-directional and multi-channel electromagnetic response signal acquisition. The present disclosure acquires rich electromagnetic response characteristics of underground electrical property medium and reduces the multi-solution property of inversion. In addition, the present disclosure breaks through the traditional single-air magnetic field detection and invents a method for simultaneous detection of aerial electric field and magnetic field. Through cooperative detection of electric field and magnetic field, the recognition ability of the underground detection target and the detection accuracy of the system are greatly improved.

[0070] It should be noted that, in this document, unless specifically indicated otherwise, having "one" element is not limited to having a single element, but can have one or more elements.

[0071] In addition, in this document, unless specifically indicated otherwise, the ordinal numbers "first", "second", etc. are only used to distinguish multiple elements with the same name, and do not indicate the existence of a hierarchy, level, execution order, or process order between them. A "first" element and a "second" element can appear together in the same component, or separately in different components. The existence of an element with a larger ordinal number does not necessarily mean the existence of another element with a smaller ordinal number.

[0072] In this document, the terms "comprises", "comprising", "includes", "including", "has", "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0073] Also, in this document, relational terms such as "first", "second", and the like can be used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises", "comprising", "includes", "including", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Additionally, unless otherwise specified, the steps of a process, method, or the like can be performed in any order or sequence and need not be performed in the order or sequence in which they are recited.

[0074] Also, unless specifically stated otherwise, or as can be clearly inferred from the specification, steps of a process, method, or the like can be performed in any order or sequence and need not be performed in the order or sequence in which they are recited. Also, the above-described embodiments can be mixed and matched with each other or with other embodiments, based on design and reliability considerations, i.e., technical features of different embodiments can be freely combined with each other to form further embodiments.

[0075] The specific embodiments described herein have been chosen for purposes of concreteness and readability. Those of ordinary skill in the art will appreciate that other embodiments can be practiced with the same or similar function without departing from the spirit and scope of the disclosure. Accordingly, the disclosure is intended to embrace all such alterations, modifications, and variations which fall within the scope of this disclosure.

Claims

1. A method for coordinated detection of airborne multi-component electric and magnetic fields using an array-type unmanned aerial vehicle (UAV), comprising: S1: Assemble and debug the cooperative detection system; S2: Based on the actual conditions of the survey area and the user's detection needs, set the system parameters of the detection system and the flight parameters of the UAV array; S3: According to the received control command, the electromagnetic field pulse signal is excited through the central primary field compensation technology; S4: Acquire horizontal component electric field signal and three-component magnetic field signal data; as well as S5: The acquired horizontal component electric field signal and three component magnetic field signal data are preprocessed, and the electrical information of the underground space in the detection area is obtained by the joint inversion method of electric field and magnetic field data. The system parameters of the detection system include the amplitude, shape, and frequency of the transmitted current of the current transmitter and the sampling rate of the electromagnetic data receiver; the flight parameters of the UAV array include the UAV array formation mode, flight altitude, flight speed, and flight path. The electrical information of the subsurface space in the detection area was obtained through a joint inversion method using electric and magnetic field data, including: S51: setting the initial resistivity model and model parameters; S5 2. Using the forward modeling models of magnetic field and electric field responses, calculate the errors between the initial resistivity model's magnetic field and electric field responses and the detected magnetic field and electric field responses to obtain the magnetic field response error and electric field response error, respectively; S53. Construct the Jacobian matrix for magnetic field and electric field data inversion using the resistivity model, and calculate the model update amount for magnetic field data inversion and electric field data inversion using the magnetic field response error and electric field response error, respectively; S54. Add the model update amount and model parameters to obtain the updated resistivity model; S55. Determine whether the fitting error of the forward modeling electric field and magnetic field response data of the updated resistivity model is less than a set threshold, and determine whether to perform iteration accordingly; and S56. Terminate when the fitting error is less than the set threshold, increment the iteration count by one when the fitting error is greater than the set threshold, and proceed to step S53. At this time, the resistivity model updated by electric field inversion is calculated from the model parameters obtained by magnetic field inversion in the previous iteration, and the resistivity model updated by magnetic field inversion is calculated from the model parameters obtained by electric field inversion in the previous iteration, until the iteration terminates when the fitting error is less than the set threshold.

2. A UAV array-type airborne multi-component electric and magnetic field cooperative detection system for implementing the detection method of claim 1, comprising: The system includes an unmanned aerial vehicle (UAV) array, a launch unit, multiple receiving units, and ground support units; among which, The drone array includes a master drone and multiple slave drones; The transmitting unit is mounted on the main UAV and is configured to transmit a single electromagnetic field pulse; the transmitting unit includes a loop source transmitter, which includes a current transmitter, a transmitting coil, and a compensation coil; The multiple receiving units are respectively mounted on the main UAV and the slave UAV, and are configured to collect electromagnetic data after an electromagnetic field pulse is applied to the area to be measured. The electromagnetic data includes a horizontal component electric field signal and a three-component magnetic field signal. Each receiving unit includes a capacitive electric field sensor, a three-component coil magnetic field sensor, and an electromagnetic data receiver. The ground auxiliary unit is configured to control the acquisition of the horizontal component electric field signal and the three component magnetic field signal, and to perform electromagnetic data processing to obtain the electrical information of the underground space in the detection area.

3. The cooperative detection system according to claim 2, wherein the capacitive electric field sensor comprises: The x-component electric field sensor is configured to point parallel to the direction of travel of the measuring line and is used to measure the x-component electric field. A y-component electric field sensor, configured to point perpendicular to the direction of travel of the measuring line, is used to measure the y-component electric field.

4. The collaborative detection system according to claim 2 or 3, wherein the capacitive electric field sensor adopts a non-contact measurement principle to convert the unknown electric field to be measured into a voltage across a capacitor; the capacitive electric field sensor is arranged at both ends of the connecting frame in the direction of the measuring line travel, and the capacitive electric field sensor includes an upper electrode plate, a lower electrode plate, a measuring circuit board, and an insulating column. The upper and lower plates are arranged in parallel to form a parallel plate capacitor, and the upper and lower plates are made of the same material, area and thickness. A measurement circuit board, wherein the input ends of the measurement circuit board are respectively connected to the upper plate and the lower plate, and the measurement circuit board includes a sampling capacitor; The insulating column is constructed to connect and fix the upper electrode plate, the lower electrode plate, and the measuring circuit board. The capacitive electric field sensor is placed in an electric field space. The charges generated on the surfaces of the upper and lower plates will form a voltage across the sampling capacitor. Electric field data can be obtained by measuring the voltage across the sampling capacitor.

5. The cooperative detection system according to claim 2, wherein the three-component coil magnetic field sensor comprises: The x-component magnetic field sensor is constructed as a semicircle with the normal of its plane pointing in the x-direction, and is used to measure the x-component magnetic field. The y-component magnetic field sensor is constructed as a semicircle with the normal of its plane pointing in the y direction, and is used to measure the y-component magnetic field. The z-component magnetic field sensor is constructed in a circular shape with the normal of its plane pointing in the z-direction, and is used to measure the z-component magnetic field.

6. In the cooperative detection system according to claim 5, the transmitting coil, the compensation coil, and the z-component magnetic field sensor are arranged in the same plane, and the radius ratio of the transmitting coil and the compensation coil is equal to the turns ratio of the transmitting coil and the compensation coil.

7. The cooperative detection system according to claim 2, wherein, The electromagnetic data receiver includes: The signal conditioning module is configured to filter and amplify the received horizontal component electric field signal and the three component magnetic field signal. The signal acquisition module includes an analog-to-digital conversion circuit and is configured to sample data from the signal conditioned by the signal conditioning module. The storage module is configured to store multi-component electric field data and magnetic field data sampled by the signal acquisition module; and The transmission module is configured to transmit the acquired multi-component electric field data and magnetic field data to the auxiliary unit; The ground support unit includes: The control device is configured to send operational control commands to the collaborative detection system; The monitoring device is configured to perform real-time monitoring of the system parameter status, multi-component electric field data, magnetic field data, and location information of the cooperative detection system; and The data processing device is configured to process electromagnetic data to obtain electrical information about the underground space of the detection area.

8. The cooperative detection system according to claim 2, further comprising: The positioning device is used to perform real-time positioning of the UAV array and obtain the latitude and longitude information of each UAV in the UAV array; Radar altimeter, used to measure the flight altitude of unmanned aerial vehicle (UAV) arrays; as well as Power supply unit, used to power the cooperative detection system.

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