Unmanned aerial vehicle array type aviation multi-component electric field and magnetic field cooperative detection system and detection method

Abstract

The invention provides an unmanned aerial vehicle array type aviation multi-component electric field and magnetic field cooperative detection system and detection method. The detection system comprises an unmanned aerial vehicle array, a transmitting unit, a plurality of receiving units and a ground auxiliary unit. The unmanned aerial vehicle array comprises a master unmanned aerial vehicle and a plurality of slave unmanned aerial vehicles; the transmitting unit is used for transmitting primary electromagnetic field pulses; the transmitting unit comprises a loop source transmitting device, and the loop source transmitting device comprises a current transmitter, a transmitting coil and a compensating coil; the plurality of receiving units are respectively mounted under the master unmanned aerial vehicle and the slave unmanned aerial vehicle and are used for acquiring electromagnetic data after the primary electromagnetic field pulse acts on the to-be-detected area, and the electromagnetic data comprise 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; and the ground auxiliary unit is used for controlling acquisition of the horizontal component electric field signal and the three-component magnetic field signal, and performing electromagnetic data processing to obtain underground space electrical information of the detection area.

Description

Technical Field

[0001] The present disclosure relates to the field of electromagnetic detection technology, and in particular to an unmanned aerial vehicle array aviation multi-component electric field and magnetic field collaborative detection system and detection method. Background Art

[0002] The transient electromagnetic method (TEM) is a geophysical method that analyzes and studies the secondary field response characteristics of the induced eddy currents generated by the underground medium under the excitation of an external field source, thereby obtaining the resistivity distribution of the underground medium. Its basic principle is to use an ungrounded loop or a grounded line source to transmit a pulse magnetic field to the underground, and during the interval of a pulse magnetic field, use a coil or a grounding electrode to detect the secondary induced eddy current field caused in the underground medium. By measuring the time-varying law of the secondary field in each time period after power failure, the geoelectric characteristics of different depths can be obtained. According to the different instrument carrying platforms, the induction electromagnetic method can be mainly divided into three modes: full aviation, semi-aerial and ground detection. Among them, the full aviation transient electromagnetic method uses a helicopter or unmanned aerial vehicle equipped with an integrated electromagnetic field transceiver and transmitter, and uses a loop source to transmit a pulse magnetic field to stimulate the underground abnormal electrical body to produce a secondary electromagnetic field response. The measured magnetic field response is sensitive to low-resistance targets and is mostly used for the detection of targets such as metal minerals and groundwater.

[0003] At present, the application of airborne electromagnetic detection technology has been relatively mature. The system uses drones or helicopters to place the entire loop source transceiver in the air for detection. It has the advantages of flexibility, low labor cost and high detection efficiency. However, traditional airborne electromagnetic detection technology only detects single-component magnetic field signals and cannot realize airborne electric field measurement, so that the ground electrical source electric field measurement system cannot be extended to drone platforms and still requires manpower to operate on the ground. It was not until recent years that the electric field sensor hardware technology has made breakthrough progress, making it possible to measure the stable electric field components in the air; on the other hand, the existing airborne electromagnetic detection system consists of a single flight platform mounted with a transmitting source and a receiving sensor. With the rapid development of software and hardware technology, the unmanned, miniaturized, integrated and arrayed geophysical detection systems have become an inevitable trend for future development. However, in the traditional single-machine flight operation mode, due to the fixed relative position of the transmitter and the receiver, the sensor measures the amount of abnormal electromagnetic response information generated by the transmitter exciting the underground electrical medium, which is limited, and it is difficult to fully obtain the electromagnetic response characteristics related to the underground electrical structure. For the detection of complex three-dimensional underground space, it faces severe multi-solution problems. Summary of the invention

[0004] In view of this, in order to at least partially solve at least one of the technical problems mentioned above, the present disclosure provides a UAV array aviation multi-component electric field and magnetic field collaborative detection system and detection method, which aims to simultaneously obtain multi-perspective, multi-parameter electromagnetic response information of underground electrical media by combining the UAV array platform and the electric field and magnetic field multi-parameter collaborative detection system, so as to improve the detection accuracy of three-dimensional targets in complex underground spaces.

[0005] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0006] An embodiment of one aspect of the present disclosure provides a drone array-type aviation multi-component electric field and magnetic field collaborative detection system, comprising: a drone array, a transmitting unit, a plurality of receiving units, and a ground auxiliary unit; wherein the drone array comprises a master drone and a plurality of slave drones; the transmitting unit is mounted under the master drone and is configured to transmit an electromagnetic field pulse; the transmitting unit comprises a loop source transmitting device, and the loop source transmitting device comprises a current transmitter, a transmitting coil, and a compensation coil; the plurality of receiving units are respectively mounted under the master drone and the slave drone, and are configured to collect electromagnetic data after an electromagnetic field pulse acts on a to-be-detected area, 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 perform electromagnetic data processing to obtain the electrical information of the underground space of the detection area.

[0007] According to an embodiment of the present disclosure, the capacitive electric field sensor includes an x-component electric field sensor and a y-component electric field sensor. The x-component electric field sensor is configured to point parallel to the direction of travel of the survey line for measuring the x-component electric field; the y-component electric field sensor is configured to point perpendicular to the direction of travel 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 the non-contact measurement principle to convert the unknown electric field to be measured into a voltage across the capacitor; the capacitive electric field sensor is arranged at the front and rear ends of the connecting skeleton in the direction of the measuring line, and the capacitive electric field sensor includes an upper plate, a lower plate, a measuring circuit board, and an insulating column: the upper plate and the lower plate are arranged in parallel to form a parallel plate capacitor, and the material, area, and thickness of the upper plate and the lower plate are the same; the input ends of the measuring circuit board are respectively connected to the upper plate and the lower plate, and the measuring circuit board includes a sampling capacitor; the insulating column is constructed to connect and fix the upper plate, the lower plate and the measuring circuit board; the capacitive electric field sensor is placed in the electric field space, and the charges generated on the surfaces of the upper plate and the lower plate will form a voltage across the sampling capacitor, and the electric field data is obtained by measuring the voltage across the sampling capacitor.

[0009] According to an embodiment of the present disclosure, the three-component coil magnetic field sensor includes: 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 constructed as a semicircle, and the normal of the plane in which it is located points to the x direction, and is used to measure the x-component magnetic field; the y-component magnetic field sensor is constructed as a semicircle, and the normal of the plane in which it is located points to the y direction, and is used to measure the y-component magnetic field; the z-component magnetic field sensor is constructed as a circle, and the normal of the plane in which it is located points to the z direction, and is used to measure the z-component magnetic field.

[0010] According to an 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 turns ratio of the transmitting coil and the compensation coil.

[0011] According to an embodiment of the present disclosure, an electromagnetic data receiver includes: 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 the three-component magnetic field signal; the signal acquisition module includes an analog-to-digital conversion circuit and is configured to perform data sampling on the signal conditioned 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; the transmission module is configured to transmit the collected multi-component electric field data and magnetic field data to the auxiliary unit;

[0012] The ground auxiliary unit includes: a control device, a monitoring device, and a data processing device. The control device is configured to send work control instructions to the collaborative detection system; the monitoring device is configured to monitor the system parameter status, multi-component electric field data, magnetic field data, and location information of the collaborative detection system in real time; and the data processing device is configured to process electromagnetic data to obtain electrical information of the underground space in the detection area.

[0013] According to the disclosed embodiment, the collaborative detection system further includes a positioning device, a radar altimeter, and a power supply device. The positioning device is used to perform real-time positioning of the drone array and obtain the longitude and latitude information of each drone in the drone array; the radar altimeter is used to measure the flight altitude of the drone array; and the power supply device is used to supply power to the collaborative detection system.

[0014] An embodiment of another aspect of the present disclosure provides a detection method based on the collaborative detection system described in any one of the above items, including: S1: assembling and debugging the collaborative detection system; S2: setting the detection system parameters and the flight parameters of the drone array according to the actual conditions of the survey area and the user's detection needs; S3: according to the received control instructions, realizing the excitation of the primary electromagnetic field pulse signal through the central primary field compensation technology; S4: collecting the horizontal component electric field signal and the three-component magnetic field signal data; and S5: pre-processing the acquired horizontal component electric field signal and the three-component magnetic field signal data, and obtaining the underground space electrical information of the detection area through the joint inversion method of the electric field and magnetic field data.

[0015] According to an embodiment of the present disclosure, the detection system parameters include the transmitting current amplitude, transmitting current shape, transmitting current frequency of the current transmitter and the sampling rate of the electromagnetic data receiver; the UAV array flight parameters include the UAV array formation mode, flight altitude, flight speed and flight route.

[0016] According to the embodiment of the present disclosure, the electrical information of the underground space of the detection area is obtained by the joint inversion method of electric field and magnetic field data, including: S51: setting the initial resistivity model and model parameters; S52: using the magnetic field and electric field response forward model to respectively calculate the errors between the magnetic field response and electric field response of the initial resistivity model and the detected magnetic field response and electric field response to obtain the magnetic field response error and the electric field response error; S53: using the resistivity model to construct the Jacobian matrix of the magnetic field and electric field data inversion, and respectively using the magnetic field response error and the electric field response error to calculate the model update amount of the magnetic field data inversion and the model update amount of the electric field data inversion; S54 : Add the model update amount and the model parameters to obtain the updated resistivity model; S55: Determine whether the fitting error of the forward electric field and magnetic field response data of the updated resistivity model is less than the set threshold, and determine whether to iterate in turn; and S56: When the fitting error is less than the set threshold, terminate; when the fitting error is greater than the set threshold, increase the number of iterations by one, and enter step S53, at which time the resistivity model updated by the electric field inversion is calculated by the model parameters obtained by the magnetic field inversion in the previous iteration, and the resistivity model updated by the magnetic field inversion is calculated by the model parameters obtained by the electric field inversion in the previous iteration, until the fitting error is less than the set threshold, the iteration is terminated. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 1 The working scenario diagram of the UAV array aviation multi-component electric field and magnetic field collaborative detection system according to the embodiment of the present disclosure is schematically shown.

[0019] Figure 2a The structure diagram of the main UAV aerial transmitting and receiving unit of the UAV array aviation multi-component electric field and magnetic field collaborative detection system according to the embodiment of the present disclosure is schematically shown.

[0020] Figure 2b The schematic diagram shows the structure of the aerial receiving unit of the drone of the drone array aviation multi-component electric field and magnetic field collaborative detection system according to the embodiment of the present disclosure.

[0021] Figure 3 The schematic diagram of the central primary field compensation technology of the UAV array aviation multi-component electric field and magnetic field collaborative detection system according to the embodiment of the present disclosure is schematically shown.

[0022] Figure 4 The internal structure diagram of the capacitive electric field sensor of the drone array aviation multi-component electric field and magnetic field collaborative detection system according to the embodiment of the present disclosure is schematically shown.

[0023] Figure 5 The flowchart of the detection method based on the UAV array aviation multi-component electric field and magnetic field collaborative detection system according to the embodiment of the present disclosure is schematically shown.

[0024] Figure 6 The electromagnetic response diagram after being processed by the central primary field compensation technology according to an embodiment of the present disclosure is schematically shown.

[0025] Figure 7a A flow chart of a method for joint inversion of electric and magnetic field data according to an embodiment of the present disclosure is schematically shown.

[0026] Figure 7b The flowchart of the joint inversion method of electric field and magnetic field data according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0027] The present invention provides a UAV array aerial multi-component electric field and magnetic field collaborative detection system and detection method, which realizes the simultaneous reception of multi-directional and multi-component electric field and magnetic field data in the air, solves the problem of single electromagnetic response collection parameters and limited information in the single-machine detection mode of traditional aerial electromagnetic detection technology, and improves the detection accuracy in the field of underground space detection.

[0028] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0029] In the embodiment of the present disclosure, a drone array aviation multi-component electric field and magnetic field collaborative detection system is provided, which is combined with Figure 1 , Figure 2a , Figure 2bAs shown, the collaborative detection system includes a drone array, a transmitting unit, a plurality of receiving units, and a ground auxiliary unit; wherein:

[0030] The drone array includes a master drone and a plurality of slave drones;

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

[0032] The multiple receiving units are mounted on the master drone and the slave drone respectively, and are configured to collect electromagnetic data after an electromagnetic field pulse acts on the area to be tested, wherein 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;

[0033] 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 perform electromagnetic data processing to obtain the electrical information of the underground space in the detection area.

[0034] The main UAV platform is equipped with both a transmitting unit and a receiving unit, and the number of the slave UAV platforms is 3 to 5, which are only equipped with receiving units, forming different transmitting and receiving distances with the main UAV platform. The compensation coil is arranged between the transmitting coil and the three-component coil magnetic field sensor, and the currents passing through the compensation coil and the transmitting coil are of the same magnitude and 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 obtain the magnetic field data of the x, y, and z components, and the capacitive electric field sensor is used to obtain the horizontal x and y component electric field data.

[0035] According to an embodiment of the present disclosure, the master drone and the slave drone platform are the same type of drones, the pod below the master drone platform includes a transmitting unit, a receiving unit and a connecting device at the same time, and the pod below the slave drone platform only includes a receiving unit and a connecting device, which keeps synchronization with the drone platform and flies in the same direction. The master drone platform and the slave drone platform can be at different heights, and the relative distance between them ranges from 30 to 150 meters to ensure detection accuracy. The connecting device may include, for example, a signal cable, a rope composite cable and a connecting skeleton, and the connecting device is used to achieve fixation or connection between the master drone, the slave drone and the corresponding transmitting unit, the receiving unit, and between the transmitting unit and the receiving unit.

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

[0037] According to the embodiments of the present disclosure, the above-mentioned current transmitter can generate continuous current waveforms of different amplitudes, frequencies and shapes according to user needs, and load them into the transmitting coil to form an aerial loop source to radiate electromagnetic fields outward; in addition, the above-mentioned current transmitter is powered separately by the drone.

[0038] According to an embodiment of the present disclosure, the above-mentioned capacitive 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 point to the x and y directions respectively, and are used to measure the 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 to the front and rear ends of the transmitting coil in the direction of travel through a connecting skeleton.

[0039] According to an embodiment of the present disclosure, the above-mentioned three-component coil magnetic field sensor includes: an x-component magnetic field sensor, a y-component magnetic field sensor and a z-component magnetic field sensor; the above-mentioned three-component coil magnetic field sensor is used to measure the x-component, y-component and z-component magnetic fields respectively, and is placed orthogonally in pairs in a hemispherical protective cover.

[0040] According to an embodiment of the present disclosure, an 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 perform data sampling on the conditioned signal. The storage module is used to store the collected multi-component electric field and magnetic field data. The transmission module is used to remotely transmit the collected multi-component electric field and magnetic field data to a ground auxiliary unit.

[0041] According to the embodiment of the present disclosure, the above-mentioned UAV aviation multi-component electric field and magnetic field cooperative detection system also includes: a positioning device for real-time positioning of the UAV array system to obtain the latitude and longitude information of the above-mentioned UAV array system; a radar altimeter for measuring the flight altitude of the UAV array system; a power supply device for powering the cooperative detection system, for example, for powering the UAV array system and the transmitting unit; the above-mentioned ground auxiliary unit includes: a control device for sending work instructions such as start, tentative, continue, and terminate to the system; a monitoring device for real-time monitoring of system status (such as detection system parameter status), electric field, magnetic field data and system position, height and other information. The data processing device is configured to be used for electromagnetic data processing to obtain the underground space electrical information of the detection area. The above-mentioned detection system system parameters may include, for example, the emission current amplitude, emission current shape, emission current frequency and electromagnetic data receiver sampling rate of the current transmitter; the UAV array flight parameters include the UAV array formation mode, flight altitude, flight speed and flight route.

[0042] Another aspect of the embodiments of the present disclosure provides a detection method based on the above-mentioned drone array aviation multi-component electric field and magnetic field collaborative detection system, such as Figure 5 As shown, the above detection method includes:

[0043] S1: Assemble and debug the collaborative detection system;

[0044] S2: Set the detection system parameters and UAV array flight parameters according to the actual situation of the survey area and the user's detection needs;

[0045] S3: According to the received control instruction, the excitation of the primary electromagnetic field pulse signal is realized through the central primary field compensation technology;

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

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

[0048] According to the present embodiment, combined with Figure 5 and Figure 7a , Figure 7b As shown in the figure, the underground space electrical information of the detection area obtained by the joint inversion method of electric field and magnetic field data includes:

[0049] S51: setting the initial resistivity model and model parameters;

[0050] S52: using the magnetic field and electric field response forward model, respectively calculating the errors between the magnetic field response and electric field response of the initial resistivity model and the detected magnetic field response and electric field response to obtain a magnetic field response error and an electric field response error;

[0051] S53: constructing Jacobian matrices for inversion of magnetic field and electric field data using the resistivity model, and calculating model update amounts for inversion of magnetic field data and model update amounts for inversion of electric field data using magnetic field response errors and electric field response errors respectively;

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

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

[0054] S56: The process terminates when the fitting error is less than the set threshold. When the fitting error is greater than the set threshold, the number of iterations increases by one, and the process enters step S53. At this time, the resistivity model updated by the electric field inversion is calculated by the model parameters obtained by the magnetic field inversion in the previous iteration. The resistivity model updated by the magnetic field inversion is calculated by the model parameters obtained by the electric field inversion in the previous iteration. The iteration is terminated until the fitting error is less than the set threshold.

[0055] According to the embodiment of the present disclosure, Figure 7a and Figure 7b As shown, in step S56, it is determined whether the fitting error of the forward electric field and magnetic field data of the updated resistivity model is less than the set threshold; if yes, the algorithm terminates; if no, the number of iterations n is increased by 1, and the process proceeds to step S53. At this time, the resistivity model updated by the electric field inversion is calculated by the model parameters obtained by the magnetic field inversion in the previous iteration, and the resistivity model updated by the magnetic field inversion is calculated by the model parameters obtained by the electric field inversion in the previous iteration. Steps S54 and S55 are entered until the iteration termination condition is met.

[0056] More specifically, firstly, the aerial electromagnetic detection system equipment is assembled and debugged, and a flight safety test of the UAV array is carried out to ensure the flight safety of the above-mentioned UAV aviation multi-component electric field and magnetic field collaborative detection system when it is working; according to the actual situation of the survey area and the user's detection needs, the system parameters and flight parameters of the above-mentioned aerial UAV multi-component electric field and magnetic field collaborative detection system are set, wherein the above-mentioned system parameters may include, for example, the transmitting current amplitude, transmitting current shape, transmitting current frequency and receiving unit sampling rate of the current transmitter, and the above-mentioned flight parameters may include, for example, the formation form of the UAV array, flight altitude, flight speed and flight route; the system starts to work according to the above-mentioned set parameters, and when the system starts to work, the pod return line source transmitting device under the main UAV transmits a pulsed electromagnetic field, and the main UAV and the slave UAV receiving units cooperate to continuously collect horizontal component electric field and three-component magnetic field data; the horizontal component electric field and three-component magnetic field data obtained by the multi-directional detection are preprocessed, and the underground space electrical information of the detection area is obtained by the joint inversion method of electric field and magnetic field data.

[0057] According to the embodiments of the present disclosure, with the help of a drone array system and a capacitive electric field sensor, the multi-directional and multi-component electric field data of an electrical source transient electromagnetic system can be conveniently measured in the air; by setting a compensation coil in the transmitting coil, the primary field electromagnetic interference of the transmitting coil on the magnetic field sensor is reduced, and relatively pure multi-directional and multi-component magnetic field data can be obtained, thereby making the analyzed underground space electrical information more accurate; using the drone array acquisition working mode, multi-directional angles, multi-component electric field and magnetic field data can be obtained simultaneously in one aerial operation; combining the multi-directional, multi-component electric field and magnetic field data joint inversion method can effectively reduce the multi-solution nature of the inversion of a single electromagnetic field parameter, and the fused system detection information is more comprehensive and accurate.

[0058] According to the embodiment of the present disclosure, Figure 1 As shown, the drone array aviation multi-component electric field and magnetic field cooperative detection system of the embodiment of the present disclosure includes a drone array, a transmitting unit, a receiving unit and a ground auxiliary unit, and has the function of multi-directionally collecting horizontal component electric field (E X and E Y ) and three-component magnetic field signals (dB X / dt, dB Y / dt and dB Z / dt direction), can realize high-precision detection of underground resistivity. Specifically, the drone array aviation multi-component electric field and magnetic field collaborative detection system radiates electromagnetic fields outward by passing pulse current into the air loop source, and causes induced eddy currents in the underground structure. The electric field and magnetic field signals generated by the induced eddy currents can be obtained from multiple directions by multiple receiving units suspended on the drone array. Finally, the resistivity information of the underground space can be obtained by analyzing and processing the received electric field and magnetic field signal data.

[0059] According to the embodiment of the present disclosure, Figure 2a and Figure 2b As shown, the master drone and the slave drone are the flight platforms of the system, which are used to carry the air return source transmitting device and the receiving device, and enable the detection system to perform aerial flight detection according to the pre-planned detection path. The drone can be remotely controlled by the staff, and its specific structure and performance parameters are not limited here. Figure 2a As shown in the figure, the main UAV air loop source subsystem includes a transmitting coil, a compensating coil, a three-component magnetic field sensor, a horizontal component electric field sensor, a current transmitter, and a data receiver. Among them, the current transmitter and the data receiver are integrated in the lower part of the UAV and powered by the UAV separately; the transmitting coil, the compensating coil, the three-component magnetic field sensor, and the electric field sensor are connected and suspended under the UAV by the main cable. Figure 2b The figure shows the receiving subsystem from the drone, which only includes the three-component magnetic field sensor, the horizontal component electric field sensor and the data receiver, but does not include the transmitting source. The data receiver is integrated in the lower part of the drone and powered by the drone alone. The three-component magnetic field sensor and the horizontal component electric field sensor are connected and suspended under the drone by the main cable.

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

[0061] According to the embodiments of the present disclosure, Figure 2a As shown, the transmitting coil and compensating coil carried by the main UAV can be wound by multiple turns of copper wire, the two are wound in opposite directions, and the turn ratio of the transmitting coil and the compensating coil is equal to the radius ratio of the transmitting coil and the compensating coil. The transmitting coil and the compensating coil are both bundled in a circular fiberglass tube, where the compensating coil is inside the transmitting coil, and the two are connected and fixed by a cable.

[0062] According to the embodiments of the present disclosure, three components of magnetic field data can be obtained 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 primary field electromagnetic interference of the transmitting coil to the coil magnetic field sensor, thereby making the acquired underground space electrical information more accurate. In addition, the three-component coil magnetic field sensor is installed in a hemispherical protective cover, and the compensation coil and the transmitting coil are indirectly connected by a composite cable to avoid direct connection that causes the sensor device to be subjected to force and bumps.

[0063] According to an 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 point to the x and y directions respectively, 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 conveniently measure the electric field components in the air without grounding. All electric field sensors have the same performance parameters and are arranged at both ends of the transmitting coil through a connecting skeleton. Each electric field sensor is 0.3~0.5m away from the edge of the transmitting coil.

[0064] According to the embodiment of the present disclosure, Figure 3 As shown, the compensation coil is arranged inside the transmitting coil, and the coil winding method of the transmitting coil and the compensation coil makes the direction of the current flowing through the transmitting coil I T The current direction of the compensation coil I B On the contrary, primary magnetic fields of equal amplitude and opposite directions are generated in the area of ​​the central receiving coil, which can better offset the strong primary field in the secondary electromagnetic field signal received by the three-component magnetic sensor, thereby realizing weak coupling between the transmitting and receiving coils, obtaining pure secondary field signals, and reducing the electromagnetic field interference of the transmitting device on the receiving device.

[0065] According to the embodiment of the present disclosure, Figure 4 As shown in the figure, the internal structure of the capacitive electric field sensor (which can be referred to as a capacitor or a flat plate capacitor) includes two symmetrical upper and lower plates, a measuring circuit and an insulating column. The upper and lower plates are two copper plates of the same area and thickness, forming a parallel plate capacitor; the measuring circuit is used to convert the measurement of the unknown electric field into the measurement of the voltage across the known capacitor; the insulating column is used to connect the upper and lower plates and the measuring circuit board. The measurement principle of the capacitive electric field sensor is as follows: Place the sensor 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 capacitance of the parallel plate capacitor and H is the relative height between the two plates. Use wires to connect the upper and lower plates and the measuring circuit board, where the core component of the measuring circuit board is a sampling capacitor C2. The charges on the parallel plates will form a small power supply voltage U at both ends of the sampling capacitor. e =Q / C2. Therefore, by measuring the voltage across the sampling capacitor, the electric field between the plates can be obtained: E=C2U e / C1H. Using a differential input circuit when measuring the sampling capacitor voltage can suppress common-mode noise and improve sensor sensitivity.

[0066] According to the embodiment of the present disclosure, Figure 6 As shown, after the primary magnetic field compensation, the pure secondary magnetic field receiving signal of the underground target can be obtained, which is conducive to reducing the dynamic range of the receiving unit and improving the quality of the early electromagnetic response signal. Furthermore, the receiving device can obtain relatively pure electromagnetic data, and by processing the electromagnetic data, a relatively clear electrical detection image of the underground target can be obtained.

[0067] So far, the embodiments of the present disclosure have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in the field can simply change or replace them.

[0068] Based on the above description, those skilled in the art should have a clear understanding of the disclosed UAV array aviation multi-component electric field and magnetic field collaborative detection system and detection method.

[0069] In summary, the present disclosure provides a drone array aviation multi-component electric field, magnetic field collaborative detection system and detection method, which uses a light and small drone as a flight carrier platform, and has the advantages of low flight cost, flexibility, and high safety; the present invention breaks through the traditional single-machine working mode of aviation, and adopts a drone array formation detection method to achieve multi-directional and multi-channel electromagnetic response signal collection. Acquire rich electromagnetic response characteristics of underground electrical media and reduce inversion multi-solutions; in addition, the present invention breaks through the traditional single aerial magnetic field detection, and invents a method for simultaneous detection of aerial electric and magnetic fields. Through the collaborative detection of electric and magnetic fields, the recognition ability of underground detection targets and the detection accuracy of the system are greatly improved.

[0070] It should be noted that, in this document, unless otherwise specified, “a” element is not limited to a single element, but may include one or more elements.

[0071] In addition, in this document, unless otherwise specified, ordinal numbers such as "first" and "second" are only used to distinguish multiple components with the same name, and do not indicate that there is a hierarchy, level, execution order, or process order between them. A "first" component and a "second" component may appear together in the same component, or appear in different components. The presence of a component with a larger ordinal number does not necessarily indicate the presence of another component with a smaller ordinal number.

[0072] In this document, unless otherwise specified, the so-called feature A "or" or "and / or" (and / or) feature B means that A exists alone, B exists alone, or A and B exist at the same time; the so-called feature A "and" (and) or "and" (and) or "and" (and) feature B means that A and B exist at the same time; the so-called "include", "comprise", "have" and "contain" mean including but not limited to these.

[0073] In addition, in this document, the terms "upper", "lower", "left", "right", "front", "back", or "between" are only used to describe the relative positions between multiple elements, and can be extended to include translation, rotation, or mirroring. In addition, in this document, unless otherwise specified, "an element is on another element" or similar descriptions do not necessarily mean that the element contacts the other element.

[0074] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0075] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A drone array aviation multi-component electric field and magnetic field collaborative detection system, comprising: An array of drones, a transmitting unit, a plurality of receiving units, and a ground support unit; wherein, The drone array includes a master drone and a plurality of slave drones; The transmitting unit is mounted under the main UAV and is configured to transmit an electromagnetic field pulse; the transmitting unit includes a loop source transmitting device, and the loop source transmitting device includes a current transmitter, a transmitting coil, and a compensation coil; The multiple receiving units are mounted on the master drone and the slave drone respectively, and are configured to collect electromagnetic data after an electromagnetic field pulse acts on the area to be tested, wherein 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 collection of the horizontal component electric field signal and the three-component magnetic field signal, and perform electromagnetic data processing to obtain the electrical information of the underground space in the detection area.

2. The collaborative detection system according to claim 1, wherein the capacitive electric field sensor comprises: An x-component electric field sensor, the x-component electric field sensor being configured to point parallel to a direction of travel of the survey line and used for measuring an x-component electric field; The y-component electric field sensor is configured to point perpendicularly to the direction of travel of the measuring line and is used to measure the y-component electric field.

3. According to the collaborative detection system of claim 1 or 2, the capacitive electric field sensor adopts a non-contact measurement principle to convert the unknown electric field to be measured into a voltage across the capacitor; the capacitive electric field sensor is arranged at the front and rear ends of the connecting skeleton in the direction of travel of the measuring line, and the capacitive electric field sensor includes an upper plate, a lower plate, a measuring circuit board, and an insulating column: The upper plate and the lower plate are arranged in parallel to form a parallel plate capacitor, and the material, area and thickness of the upper plate and the lower plate are the same; A measuring circuit board, wherein the input ends of the measuring circuit board are respectively connected to the upper plate and the lower plates, and the measuring circuit board includes a sampling capacitor; The insulating column is configured 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 the electric field space. The charges generated on the surfaces of the upper plate and the lower plate will form a voltage at both ends of the sampling capacitor. The electric field data is obtained by measuring the voltage at both ends of the sampling capacitor.

4. The collaborative detection system according to claim 1, wherein the three-component coil magnetic field sensor comprises: The x-component magnetic field sensor is constructed in a semicircular shape, with the normal of the plane pointing to the x-direction, and is used to measure the x-component magnetic field; The y-component magnetic field sensor is constructed in a semicircular shape, and the normal direction of the plane where it is located points to 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 the plane pointing to the z direction, and is used to measure the z-component magnetic field.

5. According to the collaborative detection system of claim 4, 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.

6. The cooperative detection system according to claim 1, wherein: The electromagnetic data receiver comprises: A 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 includes an analog-to-digital conversion circuit and is configured to perform data sampling on the signal conditioned by the signal conditioning module; A storage module configured to store the multi-component electric field data and magnetic field data sampled by the signal acquisition module; and a transmission module configured to transmit the collected multi-component electric field data and magnetic field data to an auxiliary unit; The ground auxiliary unit comprises: A control device configured to cooperate with the detection system to send work control instructions; A monitoring device configured to monitor in real time the system parameter status, multi-component electric field data, magnetic field data, and position information of the cooperative detection system; and The data processing device is configured to process electromagnetic data to obtain electrical information of underground space in the detection area.

7. The cooperative detection system according to claim 1, further comprising: A positioning device is used to locate the drone array in real time and obtain the longitude and latitude information of each drone in the drone array; a radar altimeter to measure the flying altitude of the drone array; as well as A power supply device is used to supply power to the collaborative detection system.

8. A detection method based on the cooperative detection system according to any one of claims 1 to 7, comprising: S1: Assemble and debug the collaborative detection system; S2: Set the detection system parameters and UAV array flight parameters according to the actual situation of the survey area and the user's detection needs; S3: According to the received control instruction, the excitation of the primary electromagnetic field pulse signal is realized through the central primary field compensation technology; S4: collecting horizontal component electric field signal and three-component magnetic field signal data; as well as S5: Preprocess the acquired horizontal component electric field signal and three-component magnetic field signal data, and obtain the underground space electrical information of the detection area through the joint inversion method of electric field and magnetic field data.

9. According to the detection method of claim 8, the detection system parameters include the transmitting current amplitude, transmitting current shape, transmitting current frequency of the current transmitter and the sampling rate of the electromagnetic data receiver; the UAV array flight parameters include the UAV array formation mode, flight altitude, flight speed and flight route.

10. According to the detection method of claim 8, obtaining the underground space electrical information of the detection area by the joint inversion method of electric field and magnetic field data comprises: S51: setting the initial resistivity model and model parameters; S52: using the magnetic field and electric field response forward model, respectively calculating the errors between the magnetic field response and electric field response of the initial resistivity model and the detected magnetic field response and electric field response to obtain a magnetic field response error and an electric field response error; S53: constructing Jacobian matrices for inversion of magnetic field and electric field data using the resistivity model, and calculating model update amounts for inversion of magnetic field data and model update amounts for inversion of electric field data using magnetic field response errors and electric field response errors respectively; S54: adding the model update amount and the model parameter to obtain an updated resistivity model; S55: judging whether the fitting error of the forward modeled electric field and magnetic field response data of the updated resistivity model is less than a set threshold, and determining whether to perform iteration in turn; and S56: The process terminates when the fitting error is less than the set threshold. When the fitting error is greater than the set threshold, the number of iterations increases by one, and the process enters step S53. At this time, the resistivity model updated by the electric field inversion is calculated by the model parameters obtained by the magnetic field inversion in the previous iteration. The resistivity model updated by the magnetic field inversion is calculated by the model parameters obtained by the electric field inversion in the previous iteration. The iteration is terminated until the fitting error is less than the set threshold.

Images