Unmanned aerial vehicle array operation frequency domain electromagnetic detection system and detection method

Abstract

The invention discloses an unmanned aerial vehicle array operation frequency domain electromagnetic detection system and detection method, and belongs to the technical field of aviation electromagnetic detection. The system comprises an unmanned aerial vehicle array, a ground control station, a transmitting device, a compensation device, a receiving device, a signal control and data storage and transmission module, an array cooperative control module and a data processing and mapping module. The invention has the advantages of low cost, miniaturization, separable frequency domain transceiving device, flexible arrangement of the transceiving device, high detection efficiency and the like; the detection method is simple and flexible, the small unmanned aerial vehicle and the detection instrument are adopted, the method has the advantage in obstacle avoidance, the flight operation limited area is reduced, and the method is particularly suitable for operation in the low-altitude complex terrain ground feature environment.

Description

Technical Field

[0001] This invention relates to the field of airborne electromagnetic detection technology, and in particular to a frequency domain electromagnetic detection system and method for unmanned aerial vehicle (UAV) array operations. Background Technology

[0002] Airborne electromagnetic methods, a commonly used geophysical exploration method, are primarily applied in mineral resource exploration, groundwater surveys, underground pollutant detection, and UXO (unexploded ordnance) detection. Airborne electromagnetic methods are divided into time-domain and frequency-domain methods. Time-domain airborne electromagnetic detection systems are generally large, heavy, and have high transmission power, suitable for deep mineral resource exploration; frequency-domain airborne electromagnetic detection systems are relatively small, lightweight, and have low transmission power, suitable for shallow exploration. Both types of systems are mostly based on manned aircraft, resulting in high operating costs, high risks at low altitudes, and poor operational flexibility. This has led to the development of unmanned aerial vehicle (UAV) airborne electromagnetic detection. However, most existing UAV airborne electromagnetic detection systems operate as stand-alone units, with detection sensors integrated onto the same UAV, making them inseparable and limiting their operational modes. Especially in complex low-altitude environments with numerous obstacles, the inability to effectively avoid obstacles hinders reliable and effective operation, leading to high operational risks. With the development of UAV swarm technology and deep learning (AI) technology, miniaturized, low-cost, swarm-based intelligent airborne electromagnetic detection systems will become a development trend. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problems of existing airborne electromagnetic detection systems, such as complex structure, high cost, and limited operation in low-altitude complex terrain and ground environment. This invention provides a frequency domain electromagnetic detection system and detection method for UAV array operation. This invention has the advantages of low cost, miniaturization, separable frequency domain transceiver devices, flexible arrangement of transceiver devices, and high detection efficiency.

[0004] A frequency domain electromagnetic detection system for unmanned aerial vehicle (UAV) array operations, comprising an UAV array, a ground control station, a transmitting device, a compensation device, a receiving device, a signal control and data transmission / storage module, an array cooperative control module, and a data processing and mapping module; The aforementioned UAV array includes a master node UAV and several auxiliary node UAVs. The master node UAV is equipped with a transmitting device, and the auxiliary node UAVs are all equipped with receiving devices and compensation devices. The master node UAV and the auxiliary node UAVs are all equipped with signal control and data storage and transmission modules as well as array collaborative control modules. The ground control station is located on the ground and communicates remotely with the UAV array and its payload. It is used by ground personnel to send control commands and parameters to the UAV array and its payload, and to receive data transmitted back to the ground by the UAV array and its payload. It can perform functions such as UAV array flight path planning and display, setting operating parameters for the UAV array and payload, and displaying status parameters.

[0005] The data processing and mapping module is installed on the ground control station. It processes the status parameters and measurement data transmitted back by the main node UAV and the auxiliary node UAV, including latitude and longitude, altitude, electromagnetic measurement data, flight speed, flight attitude, etc. Its functions include data filtering (filtering out interference signals), operation data correction (correcting for non-strict coplanarity of transceiver coils, transmission and reception distance errors, operation altitude errors, etc.), and result interpretation and mapping.

[0006] The main body of the transmitting device is a coil, which is used to generate and transmit a pulsed primary electromagnetic field to the measurement area. The transmission frequency of the primary electromagnetic field is 25Hz-96kHz, so that the conductors in the measurement area generate eddy currents based on the primary electromagnetic field to generate a secondary electromagnetic field, which then propagates to the ground surface.

[0007] The main body of the receiving device is a coil, which is used to receive secondary electromagnetic fields.

[0008] The main body of the compensation device is a coil, which filters out the primary electromagnetic field in real time when a reverse electromagnetic field is generated, ensuring that the receiving device receives a pure secondary electromagnetic field.

[0009] The coils included in the main body of the transmitting device, receiving device, and compensation device are located on a common horizontal plane during operation.

[0010] The auxiliary node drones consist of four units.

[0011] The main node UAV and several auxiliary node UAVs are all small multi-rotor UAVs.

[0012] The main node UAV is detachably connected to the launching device; the auxiliary node UAV is detachably connected to both the receiving device and the compensation device; the detachable connection method is either a plug-in or a locking method.

[0013] Signal control and data transmission / storage modules are installed on all UAVs, corresponding to their respective mission payloads. For the transmitting unit, these modules set the start time, transmission frequency, and duration of the primary electromagnetic field, communicating with the ground control station via the UAV's own data link. For the receiving unit, these modules set the sampling frequency and start time, receive and store the secondary electromagnetic field data, and communicate with the ground control station via the UAV's own data link. For the compensation unit, these modules set the filtering frequency of the reverse electromagnetic field so that it is generated simultaneously with the primary electromagnetic field, and ensure that the filtering frequency is the same as the sampling frequency.

[0014] The array collaborative control module is installed on the master node UAV and the auxiliary node UAV respectively. The master node UAV and the auxiliary node UAV can sense each other and work together to achieve precise position tracking control of the auxiliary node UAV relative to the master node UAV.

[0015] The data processing and mapping module includes a filtering software module, a correction software module, and a result interpretation and plotting software module.

[0016] Ground personnel send control commands and parameters to the UAV array and its mission payload through the ground control station. This station is used to receive data transmitted back to the ground from the UAV array and its mission payload. It can realize functions such as UAV array flight path planning and display, UAV array and payload working parameter setting and status parameter display.

[0017] There are two principles of electromagnetic detection, and this invention can adopt different schemes based on these two principles: One method is geometric depth sounding, which uses a fixed transmission frequency and changes the distance between the transmitting and receiving coils (transmission and reception distance) to achieve different detection depths. The greater the transmission and reception distance, the deeper the detection. In this invention, a fixed transmission frequency is used for the electromagnetic field. The distance between the main node UAV and the auxiliary node UAV is changed, which changes the transmission and reception distance. The greater the transmission and reception distance, the deeper the detection.

[0018] The second method is frequency sounding, which uses a fixed transmit and receive distance and changes the transmission frequency. The higher the frequency, the shallower the detection; the lower the frequency, the deeper the detection. In this invention, the distance between the main node UAV and the auxiliary node UAV is kept constant, and the transmission frequency of the electromagnetic field is changed. The higher the frequency, the shallower the detection; the lower the frequency, the deeper the detection.

[0019] The detection method using the above-mentioned UAV array operating frequency domain electromagnetic detection system includes the following steps: Step 1: Determine the scope of the operation area based on the low-altitude reconnaissance mission; based on the terrain and features of the operation area, set the topology and parameters of the UAV array, flight altitude, flight speed and survey line spacing on the ground control station, plan the flight path of the main node UAV and set the array flight control parameters; Step 2: The ground control station sends control parameters to the UAV array. The array collaborative control module sets the topology and geometric parameters of the main node UAV and the auxiliary node UAV of the UAV array. The UAVs take off in sequence, hover at the starting position of the operation, and deploy the array formation according to the settings. Step 3: The ground control station sends the operating parameters of the transmitting device, compensation device, and receiving device to the UAV array; through the signal control and data storage and transmission module, the primary electromagnetic field transmission frequency, operating time, and start-up time of the transmitting device are set; the sampling frequency and start-up time of the receiving device are set; the filtering frequency and start-up time of the reverse electromagnetic field used by the compensation device to filter the primary electromagnetic field are set; and the data storage method and remote data transmission mode are set. Step 4: The UAV array flies precisely along the planned flight path, while the launching device emits a pulsed primary electromagnetic field according to the predetermined settings; the compensation device generates a reverse electromagnetic field based on the filtering frequency to filter the primary electromagnetic field in real time; the receiving device receives the secondary electromagnetic field excited by the primary electromagnetic field in the underground medium within the measurement area; and simultaneously collects the position and time information when the secondary electromagnetic field is received. Step 5: During the flight of the UAV array, the attitude and position of each UAV are coordinated through the array cooperative control module to ensure that the working coils in the transmitting device, receiving device and compensation device are horizontally coplanar. Step 6: The signal control and data storage module synchronously stores the secondary electromagnetic field data, as well as the position and time information when the secondary electromagnetic field is received, and transmits the measured data to the ground control station in real time through the data link of each UAV. Step 7: The ground control station receives the data and imports it into the data processing and mapping module. The data is filtered by the filtering software module and corrected by the correction software module. Finally, the preliminary results are displayed on the software interface of the ground control station through the results interpretation and drawing software module. Step 8: The UAV array senses obstacles on the path, controls the geometry of the UAV array through the array cooperative control module to avoid obstacles, coordinates the flight positions of each UAV, and quickly restores the set flight array shape after obstacle avoidance. Step 9: After the UAV array completes its detection mission, unused payloads are turned off to extend its flight time. The UAV array then flies back to the landing point, hovers, lands safely in sequence, and shuts down. Ground personnel perform maintenance to prepare for the next operation.

[0020] The beneficial effects of this invention are: 1. This invention is based on UAV array operation. In addition to having all the advantages of single UAV operation (intelligent, low cost, no risk of personnel casualties, etc.), it can also significantly improve operation efficiency, has the ability to adjust the array topology in real time, flexibly configure the transmission and reception distance, and improve the detection effect of the frequency domain electromagnetic detection system. 2. The present invention features a modular design, characterized by miniaturization, lightweight, and simple structure, resulting in low cost and flexible operation. Due to the separate design of the UAV array and transceiver device, one main node UAV carries a transmitting device, and several auxiliary node UAVs each carry a compensation device and a receiving device. The primary electromagnetic field parameters of the transmitting device, the compensation signal of the compensation device, and the sampling frequency of the receiving device are set through the signal control and data storage and transmission module. The transmitting device transmits once, and several receiving devices receive simultaneously, which can realize the efficient planar grid detection function for underground or underwater targets. 3. The signal control and data storage and transmission module of the present invention stores the position, attitude, time, and secondary electromagnetic field data of the transceiver device together and transmits them to the data processing module. Through a complete data processing flow such as interference filtering and attitude error correction, it realizes the function of accurate and efficient interpretation of the detection data. 4. This invention uses miniaturized drones and detection instruments, which have advantages in obstacle avoidance and reduce the restricted area for flight operations, making it particularly suitable for operations in low-altitude complex terrain and object environments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system in Embodiment 1 of the present invention.

[0022] Figure 2 This is a system structure framework diagram of Embodiment 1 of the present invention.

[0023] Figure 3 This is a flowchart of the methods in Embodiments 2 and 3 of the present invention.

[0024] Figure 4 This is a schematic diagram illustrating the principle of the geometric sounding method described in this invention.

[0025] Figure 5 This is a schematic diagram illustrating the principle of the frequency depth sounding method described in this invention.

[0026] Figure 6 This is a contour map of apparent conductivity at a transmission frequency of 83625Hz in Embodiment 3 of the present invention.

[0027] Figure 7 This is a contour map of apparent conductivity at a transmission frequency of 63025Hz in Embodiment 3 of the present invention.

[0028] Figure 8This is a contour map of apparent conductivity at a transmission frequency of 18325Hz in Embodiment 3 of the present invention.

[0029] Figure 9 This is a contour map of apparent conductivity at a transmission frequency of 5325Hz in Embodiment 3 of the present invention.

[0030] Figure 10 This is a contour map of apparent conductivity at a transmission frequency of 1525Hz in Embodiment 3 of the present invention.

[0031] Explanation of reference numerals in the attached figures: 1. UAV array; 2. Ground control station; 3. Transmitting device; 4. Compensation device; 5. Receiving device; 6. Signal control and data transmission / storage module; 7. Array collaborative control module; 8. Data processing and mapping module; 11. Master node UAV; 12. Auxiliary node UAV. Detailed Implementation

[0032] Please see Figure 1 and Figure 2 As shown, this is Embodiment 1 of the present invention.

[0033] A frequency domain electromagnetic detection system for unmanned aerial vehicle (UAV) array operations, comprising an UAV array 1, a ground control station 2, a transmitting device 3, a compensation device 4, a receiving device 5, a signal control and data transmission / storage module 6, an array cooperative control module 7, and a data processing and mapping module 8. The drone array 1 includes one master node drone 11 and four auxiliary node drones 12. All five drones are small multi-rotor drones.

[0034] The main node UAV 11 is equipped with a transmitter 3, and the four auxiliary node UAVs 12 are all equipped with receivers 5 and compensation devices 4; the main node UAV 11 and the four auxiliary node UAVs 12 are all equipped with signal control and data storage and transmission modules 6 and array collaborative control modules 7. Ground control station 2 is located on the ground and communicates remotely with UAV array 1 and its payload. It is used by ground personnel to send control commands and parameters to UAV array 1 and its payload, and to receive data transmitted back to the ground from UAV array 1 and its payload. It can perform functions such as UAV array 1 flight path planning and display, and setting and displaying operating parameters and status parameters for UAV array 1 and its payload.

[0035] The data processing and mapping module 8 is installed on the ground control station 2. It processes the status parameters and measurement data transmitted back by the main node UAV 11 and the four auxiliary node UAVs 12, including latitude and longitude, altitude, electromagnetic measurement data, flight speed, and flight attitude. Its functions include data filtering (filtering out interference signals), operation data correction (correcting for non-strict coplanarity of transceiver coils, transmission and reception distance errors, and operation altitude errors), and result interpretation and mapping.

[0036] The main body of the transmitting device 3 is a coil, which is used to generate and transmit a pulsed primary electromagnetic field to the measurement area. The transmission frequency range of the primary electromagnetic field is 25Hz-96kHz, so that the conductor in the measurement area generates a secondary electromagnetic field based on the primary electromagnetic field to generate eddy currents and propagate to the ground surface.

[0037] The main body of the receiving device 5 is a coil, which is used to receive secondary electromagnetic fields.

[0038] The main body of the compensation device 4 is a coil, which filters out the primary electromagnetic field in real time when a reverse electromagnetic field is generated, ensuring that the receiving device 5 receives a pure secondary electromagnetic field.

[0039] The main node UAV 11 is detachably connected to the transmitter 3 via a plug-in method; the auxiliary node UAV 12 is detachably connected to the receiver 5 and the compensation device 4 via a plug-in method.

[0040] During operation, the coils included in the main bodies of the transmitting device 3, receiving device 5, and compensation device 4 are located on a common horizontal plane.

[0041] Signal control and data transmission / storage modules 6 are installed on all UAVs, corresponding to their respective mission payloads. For the transmitting device 3, it sets the start time, transmission frequency, and duration of the primary electromagnetic field, communicating with the ground control station 2 via the UAV's own data link. For the receiving device 5, it sets the sampling frequency and start time, receives and stores the secondary electromagnetic field data, communicating with the ground control station 2 via the UAV's own data link. For the compensation device 4, it sets the filtering frequency of the reverse electromagnetic field so that the reverse electromagnetic field and the primary electromagnetic field are generated simultaneously, and makes the filtering frequency the same as the sampling frequency.

[0042] The array collaborative control module 7 is installed on the main node UAV 11 and the four auxiliary node UAVs 12. The main node UAV 11 and the four auxiliary node UAVs 12 can sense each other and work together to achieve precise position tracking control of the auxiliary node UAVs 12 relative to the main node UAV 11.

[0043] The data processing and mapping module 8 includes a filtering software module, a correction software module, and a result interpretation and plotting software module.

[0044] Ground personnel send control commands and parameters to UAV array 1 and its mission payload through ground control station 2. This station is used to receive data transmitted back to the ground from UAV array 1 and its mission payload. It can realize functions such as flight path planning and display of UAV array 1, setting working parameters of UAV array 1 and payload, and displaying status parameters.

[0045] There are two principles of electromagnetic detection, and this invention adopts different schemes based on these two principles: One method is geometric depth sounding, which uses a fixed transmission frequency and changes the distance between the transmitting and receiving coils (transmission and reception distance) to achieve different detection depths. The greater the transmission and reception distance, the deeper the detection. In this invention, a fixed transmission frequency is used for the electromagnetic field. The distance between the main node UAV 11 and the auxiliary node UAV 12 is changed, which changes the transmission and reception distance. The greater the transmission and reception distance, the deeper the detection.

[0046] The second method is frequency sounding, which uses a fixed transmission and reception distance and changes the transmission frequency. The higher the frequency, the shallower the detection; the lower the frequency, the deeper the detection. In this invention, the distance between the main node UAV 11 and the auxiliary node UAV 12 is kept constant, and the transmission frequency of the electromagnetic field is changed. The higher the frequency, the shallower the detection; the lower the frequency, the deeper the detection.

[0047] Please see Figures 1 to 4 This is Embodiment 2 of the present invention.

[0048] The detection method using the UAV array operation frequency domain electromagnetic detection system in Embodiment 1 above includes the following steps: Step 1: Determine the scope of the operation area based on the low-altitude reconnaissance mission; based on the terrain and features of the operation area, set the topology and parameters, flight altitude, flight speed and survey line spacing of the UAV array 1 on the ground control station 2, plan the flight path of the main node UAV 11 and set the array flight control parameters. Step 2: Ground control station 2 sends control parameters to UAV array 1. The array collaborative control module 7 sets the topology and geometric parameters of the main node UAV 11 and auxiliary node UAV 12 of UAV array 1. The UAVs take off sequentially, hover at the starting point of the operation, 1 meter above the ground, and deploy into the array formation as set. The geometric depth sounding method is selected, using a fixed transmission frequency. Different detection depths are achieved by changing the transmission and reception distance; the greater the transmission and reception distance, the deeper the detection. In this embodiment, the primary electromagnetic field uses a fixed transmission frequency of 50kHz. By changing the distance between the main node UAV 11 and auxiliary node UAV 12, the relative distance between the four auxiliary node UAVs 12 and the main node UAV 11 remains equal at all times. The transmission and reception distance changes; the greater the transmission and reception distance, the deeper the detection.

[0049] Step 3: Ground control station 2 sends the operating parameters of transmitter 3, compensation device 4, and receiver 5 to UAV array 1; and sets the primary electromagnetic field transmission frequency, operating time, and start-up time of transmitter 3, the sampling frequency and start-up time of receiver 5, the filtering frequency and start-up time of the reverse electromagnetic field of compensation device 4 used to filter the primary electromagnetic field, and sets the data storage method and remote data transmission mode through signal control and data storage and transmission module 6. Step 4: The UAV array 1 flies precisely along the planned flight path, while the launching device 3 emits a pulsed primary electromagnetic field according to the predetermined settings; the compensation device 4 generates a reverse electromagnetic field based on the filtering frequency to filter the primary electromagnetic field in real time; the receiving device 5 receives the secondary electromagnetic field excited by the primary electromagnetic field in the underground medium within the measurement area; and simultaneously collects the position and time information when the secondary electromagnetic field is received. Step 5: During the flight of UAV array 1, the attitude and position of each UAV are coordinated by array cooperative control module 7 to ensure that the working coils in the transmitting device 3, receiving device 5 and compensation device 4 are horizontally coplanar. Step 6: The signal control and data storage module 6 synchronously stores the secondary electromagnetic field data, as well as the position and time information when the secondary electromagnetic field is received, and transmits the measured data to the ground control station 2 in real time through the data link of each UAV. Step 7: Ground control station 2 receives data and imports it into the data processing and mapping module 8. The data is filtered by the filtering software module and corrected by the correction software module. Finally, the preliminary results are displayed on the software interface of ground control station 2 by the result interpretation and drawing software module. Step 8: The UAV array 1 senses obstacles on the path, controls the geometry of the UAV array 1 through the array cooperative control module 7 to avoid obstacles, coordinates the flight positions of each UAV, and quickly restores the set flight array shape after obstacle avoidance. Step 9: After completing the detection mission, UAV array 1 shuts down unused payloads to extend its flight time. UAV array 1 then flies back to the landing point, hovers, lands safely in sequence, and shuts down. Ground personnel perform maintenance to prepare for the next operation.

[0050] Please see Figures 1 to 3 , Figures 5 to 10 This is Embodiment 3 of the present invention.

[0051] The detection method using the UAV array operation frequency domain electromagnetic detection system in Embodiment 1 above includes the following steps: Step 1: Determine the scope of the operation area based on the low-altitude reconnaissance mission; based on the terrain and features of the operation area, set the topology and parameters, flight altitude, flight speed and survey line spacing of the UAV array 1 on the ground control station 2, plan the flight path of the main node UAV 11 and set the array flight control parameters. Step 2: Ground control station 2 sends control parameters to UAV array 1. The array collaborative control module 7 sets the topology and geometric parameters of the main node UAV 11 and auxiliary node UAV 12 of UAV array 1. The UAVs take off sequentially, hover at the starting point of the operation, 1 meter above the ground, and deploy into the array formation as set. Frequency sounding is selected, using a fixed transmit / receive distance. Changing the transmission frequency results in shallower detection with higher frequencies and deeper detection with lower frequencies. In this embodiment, the distance between the main node UAV 11 and auxiliary node UAV 12 is kept constant. The transmission frequency of the electromagnetic field is changed to 83625Hz, 63025Hz, 18325Hz, 5325Hz, and 1525Hz, respectively, resulting in detection depths of 0.5m, 1m, 1.8m, 2.5m, and 4.6m. Higher frequencies result in shallower detection and lower frequencies result in deeper detection.

[0052] Step 3: Ground control station 2 sends the operating parameters of transmitter 3, compensation device 4, and receiver 5 to UAV array 1; and sets the primary electromagnetic field transmission frequency, operating time, and start-up time of transmitter 3, the sampling frequency and start-up time of receiver 5, the filtering frequency and start-up time of the reverse electromagnetic field of compensation device 4 used to filter the primary electromagnetic field, and sets the data storage method and remote data transmission mode through signal control and data storage and transmission module 6. Step 4: The UAV array 1 flies precisely along the planned flight path, while the launching device 3 emits a pulsed primary electromagnetic field according to the predetermined settings; the compensation device 4 generates a reverse electromagnetic field based on the filtering frequency to filter the primary electromagnetic field in real time; the receiving device 5 receives the secondary electromagnetic field excited by the primary electromagnetic field in the underground medium within the measurement area; and simultaneously collects the position and time information when the secondary electromagnetic field is received. Step 5: During the flight of UAV array 1, the attitude and position of each UAV are coordinated by array cooperative control module 7 to ensure that the working coils in the transmitting device 3, receiving device 5 and compensation device 4 are horizontally coplanar. Step 6: The signal control and data storage module 6 synchronously stores the secondary electromagnetic field data, as well as the position and time information when the secondary electromagnetic field is received, and transmits the measured data to the ground control station 2 in real time through the data link of each UAV. Step 7: Ground control station 2 receives data and imports it into the data processing and mapping module 8. The data is filtered by the filtering software module and corrected by the correction software module. Finally, the preliminary results are displayed on the software interface of ground control station 2 by the result interpretation and drawing software module. Step 8: The UAV array 1 senses obstacles on the path, controls the geometry of the UAV array 1 through the array cooperative control module 7 to avoid obstacles, coordinates the flight positions of each UAV, and quickly restores the set flight array shape after obstacle avoidance. Step 9: After completing the detection mission, UAV array 1 shuts down unused payloads to extend its flight time. UAV array 1 then flies back to the landing point, hovers, lands safely in sequence, and shuts down. Ground personnel perform maintenance to prepare for the next operation.

Claims

1. A frequency domain electromagnetic detection system for unmanned aerial vehicle (UAV) array operations, characterized in that: The system includes an unmanned aerial vehicle (UAV) array (1), a ground control station (2), a transmitter (3), a compensation device (4), a receiver (5), a signal control and data storage and transmission module (6), an array cooperative control module (7), and a data processing and mapping module (8). The UAV array (1) includes a master node UAV (11) and several auxiliary node UAVs (12). The master node UAV (11) is equipped with a transmitter (3), and the several auxiliary node UAVs (12) are all equipped with receivers (5) and compensation devices (4). The master node UAV (11) and the several auxiliary node UAVs (12) are all equipped with signal control and data transmission and storage modules (6) and array coordination control modules (7). The ground control station (2) is located on the ground and communicates remotely with the UAV array (1) and its onboard mission payload; the data processing and mapping module (8) is installed on the ground control station (2).

2. The frequency domain electromagnetic detection system for UAV array operation according to claim 1, characterized in that: The main body of the transmitting device (3) is a coil, which is used to generate and transmit a pulsed primary electromagnetic field to the measurement area. The transmission frequency of the primary electromagnetic field is 25Hz-96kHz. After the underground object is subjected to electromagnetic action, it induces a secondary electromagnetic field and propagates to the surface. The main body of the receiving device (5) is a coil, which is used to receive secondary electromagnetic fields; The main body of the compensation device (4) is a coil, which filters out the primary electromagnetic field in real time when a reverse electromagnetic field is generated, ensuring that the receiving device (5) receives a pure secondary electromagnetic field.

3. The frequency domain electromagnetic detection system for UAV array operation according to claim 2, characterized in that: The coils included in the main body of the transmitting device (3), receiving device (5) and compensation device (4) are located on a common horizontal plane during operation.

4. The frequency domain electromagnetic detection system for UAV array operation according to claim 3, characterized in that: The data processing and mapping module (8) includes a filtering software module, a correction software module, and a result interpretation and mapping software module.

5. The frequency domain electromagnetic detection system for unmanned aerial vehicle array operation according to claim 1, characterized in that: The auxiliary node UAV (12) consists of four aircraft.

6. The frequency domain electromagnetic detection system for UAV array operation according to claim 5, characterized in that: The main node UAV (11) and the four auxiliary node UAVs (12) are all small multi-rotor UAVs.

7. The frequency domain electromagnetic detection system for UAV array operation according to claim 4, characterized in that: The main node UAV (11) is detachably connected to the transmitting device (3); the auxiliary node UAV (12) is detachably connected to the receiving device (5) and the compensation device (4); the detachable connection method is either plug-in or latching.

8. The detection method using the UAV array operation frequency domain electromagnetic detection system according to claim 4, characterized in that: Includes the following steps: Step 1: Determine the scope of the operation area based on the low-altitude detection mission; Based on the terrain and features of the operation area, set the topology and parameters, flight altitude, flight speed and survey line spacing of the UAV array (1) on the ground control station (2), plan the flight path of the main node UAV (11), and set the array flight control parameters. Step 2: The ground control station (2) sends control parameters to the UAV array (1). The array collaborative control module (7) sets the topology and geometric parameters of the main node UAV (11) and auxiliary node UAV (12) of the UAV array (1). The UAVs take off in sequence, hover at the starting point of the operation, and unfold the array formation according to the settings. Step 3: The ground control station (2) sends the operating parameters of the transmitter (3), compensation device (4), and receiver (5) to the UAV array (1); and sets the primary electromagnetic field transmission frequency, operating time, and start-up time of the transmitter (3) through the signal control and data storage and transmission module (6), sets the sampling frequency and start-up time of the receiver (5), sets the filtering frequency and start-up time of the reverse electromagnetic field used by the compensation device (4) to filter the primary electromagnetic field, and sets the data storage method and remote data transmission mode. Step 4: The UAV array (1) flies precisely along the planned flight path, while the launching device (3) emits a pulsed primary electromagnetic field according to the predetermined settings; the compensation device (4) generates a reverse electromagnetic field based on the filtering frequency to filter the primary electromagnetic field in real time; the receiving device (5) receives the secondary electromagnetic field excited by the primary electromagnetic field in the underground medium within the measurement area; and simultaneously collects the position and time information when the secondary electromagnetic field is received. Step 5: During the flight of the UAV array (1), the attitude and position of each UAV are coordinated by the array cooperative control module (7) to ensure that the working coils in the transmitting device (3), receiving device (5) and compensation device (4) are horizontally coplanar; Step 6: The signal control and data storage module (6) synchronously stores the secondary electromagnetic field data as well as the position and time information when the secondary electromagnetic field is received, and transmits the measured data to the ground control station (2) in real time through the UAV’s built-in data link. Step 7: The ground control station (2) receives the data and imports it into the data processing and mapping module (8). The data is filtered by the filtering software module and corrected by the correction software module. Finally, the preliminary results of the processing are displayed on the software interface of the ground control station (2) by the result interpretation and drawing software module. Step 8: The UAV array (1) senses obstacles on the path, controls the geometry of the UAV array (1) through the array cooperative control module (7) to avoid obstacles, coordinates the flight positions of each UAV, and quickly restores the set flight array shape after avoiding obstacles. Step 9: After the UAV array (1) completes the detection mission, it shuts down the unused mission payload to extend the flight time. The UAV array (1) flies back to the landing point and hovers. It lands safely in sequence and shuts down. Ground personnel perform maintenance to prepare for the next operation.

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