Semi-aviation transient electromagnetic acquisition device and method for calibrating data drift in real time

Abstract

The invention provides a semi-aviation transient electromagnetic acquisition device and method for calibrating data drift in real time, and relates to the technical field of data calibration, and the device comprises an electromagnetic data acquisition unit which receives a secondary induction signal generated by a ground transmitting end through a transient electromagnetic hollow induction coil disposed in a coil storage cabin of an unmanned aerial vehicle, and transmits the secondary induction signal to an unmanned aerial vehicle; self-adaptive gain control is carried out according to the signal intensity to obtain real-time electromagnetic data; the flight control unit monitors the swing amplitude and frequency of the coil in real time according to the inclination angle and acceleration data fed back by the sensor in the coil storage cabin, and carries out flight attitude adjustment and control; the drift calibration unit adopts a static reference mode for calibration at the beginning stage of flight; and switching to a dynamic reference mode in the flight process, and carrying out self-adaptive calibration on the real-time data stream based on a sliding window. According to the invention, drift calibration of traditional software post-processing is migrated to a hardware acquisition stage, so that synchronous completion of data acquisition and drift compensation is realized.

Description

Technical Field

[0001] This invention relates to the field of data calibration technology, specifically to a semi-airborne transient electromagnetic acquisition device and method for real-time calibration of data drift. Background Technology

[0002] In existing semi-airborne transient electromagnetic detection technologies, the detected data often suffers from zero-point drift. This zero-point drift primarily originates from the input offset voltage of the operational amplifier. This offset voltage is amplified exponentially after multiple stages of amplification, causing a shift in the system output. This offset is inherent to the circuit and drifts with time and temperature changes. Furthermore, during high-altitude flight, drastic temperature differences cause changes in electronic component parameters, such as input offset voltage, resistance, and capacitance values. In transient electromagnetic methods, especially the secondary induced signal, is very weak, while the zero-point drift often reaches the same order of magnitude as or even higher than the true signal. If these drifts are not addressed, it may lead to misjudgments of geological structures or the location of ore bodies.

[0003] Currently, zero-point drift is generally addressed by software and algorithms after data acquisition. However, this method cannot solve the drift problem in real time and increases the complexity of backend digital signal processing, making it difficult to guarantee data stability in complex environments. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a semi-airborne transient electromagnetic acquisition device and method for real-time data drift calibration, migrating drift calibration from traditional software post-processing to the hardware acquisition stage, thereby achieving simultaneous data acquisition and drift compensation.

[0005] According to some embodiments, the present invention adopts the following technical solution: A semi-airborne transient electromagnetic data acquisition device for real-time data drift calibration includes a flight control unit, an electromagnetic data acquisition unit, and a drift calibration unit mounted on an unmanned aerial vehicle (UAV). The electromagnetic data acquisition unit receives secondary induction signals generated by the ground transmitter through a transient electromagnetic hollow induction coil installed in the UAV coil storage compartment, and performs adaptive gain control based on the signal strength to obtain real-time electromagnetic data. The flight control unit monitors the swing amplitude and frequency of the coil in real time based on the tilt angle and acceleration data fed back by the sensors in the coil storage compartment, and performs flight attitude adjustment and control. The drift calibration unit performs calibration using a static reference mode at the start of flight; during flight, it switches to a dynamic reference mode to perform adaptive calibration of the real-time data stream based on a sliding window.

[0006] According to some embodiments, the present invention adopts the following technical solution: A semi-airborne transient electromagnetic data acquisition method for real-time data drift calibration involves using a UAV carrying a semi-airborne transient electromagnetic data acquisition device to acquire and calibrate electromagnetic data in real time. The specific steps during UAV flight are as follows: By using a transient electromagnetic hollow induction coil installed in the drone's coil storage compartment, the system receives secondary induction signals generated by the ground transmitter and performs adaptive gain control based on the signal strength to obtain real-time electromagnetic data. Two modes, static reference mode and dynamic reference mode, are used to perform drift calibration on real-time electromagnetic data to obtain calibrated electromagnetic data. During flight, the tilt angle and acceleration data fed back by sensors in the coil storage compartment are used to monitor the swing amplitude and frequency of the coil in real time, and to adjust and control the flight attitude.

[0007] According to some embodiments, the present invention adopts the following technical solution: A computer program product includes a computer program that, when executed by a processor, implements the aforementioned semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0008] According to some embodiments, the present invention adopts the following technical solution: A non-transitory computer-readable storage medium is provided for storing computer instructions, which, when executed by a processor, implement a semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0009] According to some embodiments, the present invention adopts the following technical solution: An electronic device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform a semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a semi-airborne transient electromagnetic data acquisition device for real-time data drift calibration. It migrates drift correction from traditional software post-processing to the hardware acquisition stage, constructing a dual calibration mode of "static reference mode + dynamic reference mode." Drift parameters are stored in FLASH memory, enabling simultaneous data acquisition and drift compensation. The FLASH-stored parameters can be preserved for over 10 years, preventing data loss in the event of power failure. The modular design allows for portability to various electromagnetic detection devices. Based on a calibration method involving pre-flight automatic triggering, autonomous input isolation, static sampling, non-volatile storage, and real-time dynamic correction, drift is eliminated during the data acquisition stage, achieving full-process compensation and stability improvement for data offset from the source.

[0011] 2. This invention discloses a multi-rotor UAV structure suitable for transient electromagnetic detection, which features a central coil storage compartment, a coaxial reversing motor, and an insulated wing design, achieving the dual objectives of stable flight attitude and suppression of electromagnetic interference.

[0012] 3. This invention discloses a design based on a split hollow induction coil, which supports the replacement of coils with different numbers of turns / diameters within 5 minutes, adapting to multi-depth detection requirements. Combined with a built-in attitude sensor and signal receiving / synchronization module, it improves the attitude perception and signal synchronization accuracy of the coil in flight.

[0013] 4. The semi-airborne transient electromagnetic acquisition device of the present invention has a multi-channel parallel receiving system with adaptive gain control, dynamic channel switching, and redundant sampling retention mechanism to ensure continuous data acquisition capability with high dynamic range and high signal-to-noise ratio. Attached Figure Description

[0014] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0015] Figure 1 This is a structural diagram of the semi-airborne transient electromagnetic acquisition device of Example 1. Detailed Implementation The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] Example 1 One embodiment of the present invention provides a semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift, such as... Figure 1 As shown, this includes the flight control unit, electromagnetic data acquisition unit, and drift calibration unit installed on the UAV. The electromagnetic data acquisition unit receives secondary induction signals generated by the ground transmitter through a transient electromagnetic hollow induction coil installed in the UAV coil storage compartment, and performs adaptive gain control based on the signal strength to obtain real-time electromagnetic data. The flight control unit monitors the swing amplitude and frequency of the coil in real time based on the tilt angle and acceleration data fed back by the sensors in the coil storage compartment, and performs flight attitude adjustment and control. The drift calibration unit performs calibration using a static reference mode at the start of flight; during flight, it switches to a dynamic reference mode to perform adaptive calibration of the real-time data stream based on a sliding window.

[0019] As one embodiment, the present invention provides a semi-airborne transient electromagnetic data acquisition device for real-time calibration of data drift. This device migrates drift calibration from traditional software post-processing to the hardware acquisition stage, enabling simultaneous data acquisition and drift compensation. The specific implementation process is as follows: The Semi-Airborne Transient Electromagnetic Method (SATEM) is a hybrid geophysical exploration technology that combines ground-based transmission and airborne reception. It is primarily used to detect underground electrical structures. Typically, it includes a transmitter and a receiver. The transmitter lays a high-power transmitting coil or long conductor on the ground to send transient current pulses (typically step or rectangular waves) underground, exciting underground eddy current fields. The receiver uses a magnetic sensor (such as a high-sensitivity coil or superconducting magnetometer) carried by a UAV, helicopter, or fixed-wing aircraft to measure the secondary decaying magnetic field (i.e., the secondary induced signal) in the air. By analyzing the time-domain characteristics of the decay curve, the underground resistivity distribution is inverted to obtain the underground electrical structure. This embodiment focuses on "measuring the secondary decaying magnetic field (i.e., the secondary induced signal) in the air" and "signal post-processing," without involving the analysis or inversion of time-domain characteristics. The following describes the semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0020] (I) Unmanned Aerial Vehicle (UAV) Designed Specifically for Semi-Airborne Transient Electromagnetic Acquisition Devices The drone comprises a hollow frame, a power system, and a coil storage compartment. The drone employs a multi-rotor structure with a high-strength, lightweight hollow frame equipped with multiple arms, each with a power system at its end. A coil storage compartment is located in the center of the frame to house the separate receiving coil, ensuring its stable and secure attachment to the drone during flight. This prevents data quality degradation due to shaking or swaying, and also solves problems such as inaccurate positioning and susceptibility to external interference found in traditional mounting methods.

[0021] The power system includes a coaxially distributed rotor shaft, an insulated wing, and a double-layer motor. The insulated wing consists of upper and lower layers, both connected to the rotor shaft. The inner and outer layers of the double-layer motor rotate in opposite directions to eliminate electromagnetic interference generated when the inner rotor rotates. Furthermore, the insulated wing does not generate electromagnetic interference by cutting magnetic field lines, ensuring the purity of the detection signal.

[0022] The coil storage compartment is used to house the separate receiving coil, and its specific structure includes: 1) Storage recess: The coil storage compartment has multiple coil storage grooves, and the grooves are lined with anti-slip and shock-absorbing pads made of a material with good elasticity and memory function. The surface is soft and has a high coefficient of friction, which can provide good protection for the receiving coil.

[0023] 2) Fixed latch: The storage groove is evenly distributed with multiple coil fixing buckles. The buckles are made of soft leather, which can not only firmly fix the coil, but also avoid damage to the appearance of the coil caused by hard buckles.

[0024] 3) Quick disassembly design: The coil storage compartment and the drone frame adopt a modular design and are connected through a quick-disassembly interface, which facilitates the installation and replacement of the receiving coil.

[0025] Based on the structure of the aforementioned UAV, flight attitude adjustment and control are achieved, thereby automatically eliminating coil oscillation, specifically as follows: 1) Oscillation detection and feedback: High-precision tilt and acceleration sensors are installed in the coil storage compartment of the drone to monitor the attitude changes and acceleration information of the receiving coil in real time. The data collected by the sensors is transmitted to the flight control unit in real time through the data transmission module.

[0026] 2) Posture adjustment and control: Based on tilt and acceleration data fed back from sensors and combined with a preset control algorithm, the flight control unit automatically calculates the attitude parameters that need to be adjusted. By adjusting the speed and direction of the coaxial dual-layer motors, the UAV can fine-tune its flight attitude in real time, thereby counteracting the oscillation of the receiving coil. For example, when the sensor detects that the receiving coil is oscillating in a certain direction, the flight control unit will adjust the speed of the motor in the corresponding direction to generate a reverse torque, restoring the coil to a stable state.

[0027] The control algorithm here can employ intelligent control algorithms such as fuzzy control, PID control, or adaptive control. Based on the real-time monitored swing amplitude and frequency, it dynamically adjusts control parameters to achieve rapid and accurate swing suppression. This intelligent control algorithm can automatically optimize the control effect according to different flight states and environmental conditions, ensuring the receiving coil remains stable under various complex conditions. For example, a method combining PID control and extended Kalman filtering (EKF) is used: sensor monitoring of swing amplitude and frequency data → preprocessing (filtering, outlier removal) → EKF attitude estimation → PID error calculation → control output → actuator → closed-loop feedback to achieve attitude adjustment and control. This algorithm, through multi-sensor fusion and closed-loop control, can achieve high-precision attitude stabilization in the complex electromagnetic environment of a semi-aircraft transient electromagnetic system, ensuring the validity of the detected data.

[0028] This UAV is suitable for semi-airborne transient electromagnetic detection systems and can be used for geological exploration and resource surveys in areas with complex geological and topographical conditions, such as high-altitude cold regions, high-altitude mountains, deserts, Gobi deserts, forested areas, and karst areas. By carrying a semi-airborne transient electromagnetic acquisition device on the UAV, it can quickly and efficiently acquire geological information over large areas, providing important data support and technical means for geological exploration, mineral resource development, environmental monitoring, and other fields.

[0029] (ii) Transient electromagnetic hollow induction coils used for acquiring electromagnetic signals The coil body adopts a multi-turn hollow coil structure with no magnetic core, avoiding magnetic saturation and hysteresis losses and ensuring good linear frequency characteristics. In terms of material selection, the coil conductor uses high-conductivity copper wire with an outer insulating layer to reduce electromagnetic interference. The coil support structure uses lightweight, high-strength non-magnetic materials, such as carbon fiber composites. Regarding size optimization, the number of turns and diameter of the coil are optimized according to the detection depth and resolution requirements. Through finite element analysis, the optimal coil size is determined to be radii of 5m, 6m, 7m, 8m, 9m, and 10m to improve signal sensitivity and signal-to-noise ratio. For the split structure, the receiving coil adopts a split design, with the coil shell and top cover connected and fixed by a latch. The internal coil can be replaced with coils of different numbers of turns and materials according to detection needs.

[0030] Built-in sensors: High-precision tilt and acceleration sensors are integrated inside the receiving coil storage compartment to monitor the coil's attitude changes and acceleration information in real time, providing data support for the automatic sway elimination function.

[0031] This embodiment also optimizes the damping and resonant frequency of the coil, specifically as follows: 1) Damping ratio design: According to research, the coil can reach stable output the fastest when the damping ratio is 0.9118. By adjusting the resistance and inductance of the coil, the damping ratio is designed to be 0.9118 to reduce the impact of the transient process on the signal.

[0032] 2) Resonant frequency adjustment: Increasing the resonant frequency can improve the coil's response speed and received energy. Therefore, by optimizing the coil's inductance and distributed capacitance, the resonant frequency is set above the inflection point of the speed increase to ensure the overall performance of the coil.

[0033] Specifically, based on the detection requirements of the transient electromagnetic system and the electromagnetic coupling characteristics of the coil, a reasonable range of resonant frequency is determined. The "inflection point" of the system's growth rate is determined through experiments or simulations—that is, when the resonant frequency exceeds a certain critical value. By reducing the coil inductance, lowering the distributed capacitance, optimizing parameters, and through experimental verification and tuning, the transient response speed of the coil is significantly improved.

[0034] (III) Electromagnetic Data Acquisition Unit To adapt to the varying signal strength requirements of semi-airborne transient electromagnetic detection in complex environments, this paper proposes an adaptive electromagnetic data acquisition unit addressing challenges such as large dynamic range of signal strength, fast transient signal response, and complex airborne interference. The unit features automatic range switching, high linearity amplification, multi-channel parallel sampling, and linkage with a zero-point drift calibration mechanism. This ensures the device maintains a high signal-to-noise ratio and high dynamic response characteristics even during flight detection with drastic changes in signal strength. Key modules include: 1) Multi-channel parallel sampling structure The electromagnetic data acquisition unit has multiple built-in synchronous (Analog-to-Digital Converter) ADCs. The ADCs convert the analog signals acquired by the coils into digital signals. Each ADC is fixedly connected to an amplifier module, forming a "fixed sampling rate-fixed gain" pair. After parallel acquisition by each channel, the control logic selects the best acquired data as the main data output. The channels here include, in sequence, the coil signal, the amplifier module (multi-level variable gain), the anti-interference filter / limiting circuit, the parallel sampling of the multi-channel ADC, the digital logic selects the best channel, and the output is sent to the data processing unit.

[0035] It avoids timing errors introduced during channel gain switching; it can simultaneously retain data from different gain channels for later analysis and backup; and it can automatically degrade to a backup channel when the main data is saturated or severely interfered with.

[0036] 2) Amplifier Module Based on a multi-stage variable gain amplifier, a three-stage cascaded amplification structure is adopted. Each stage of the amplifier can realize high, medium and low gain adjustment, for example, the gain can be set to: ×1, ×10, ×100. Each stage of the amplifier has a pre-amplifier overvoltage protection and noise filtering circuit to ensure that there is no saturation or distortion when a strong signal is input. The amplifiers all use low offset and low noise operational amplifier chips, and are used in conjunction with a drift calibration module to automatically calibrate the baseline offset.

[0037] The adaptive gain control algorithm is used to achieve dynamic switching between multiple stages of variable gain amplifiers, specifically: By detecting the peak and root mean square values ​​of the sampled signal in the receiving channel in real time, the current signal strength is determined, and a gain control command is issued: if the signal strength is lower than the preset lower threshold, it automatically switches to the high gain channel; if the signal strength is higher than the upper threshold, it automatically switches to the low gain channel to prevent signal saturation; all gain switching is performed within the signal stable range to avoid interference introduced by transient switching.

[0038] Signal strength is determined based on the peak value and root mean square (RMS) of the signal. The peak value is the maximum instantaneous amplitude of the signal in the time domain, reflecting the extreme value of the signal. The RMS value is the effective value of the signal, representing the average power of the signal (for resistive loads, the power is proportional to the square of RMS). There are two core indicators for judging signal strength: the RMS value and the ratio of peak value to RMS value (peak-to-average power ratio, PAPR). The RMS value directly reflects the average energy or strength of the signal; the larger the RMS, the stronger the signal. A high PAPR indicates that the signal has violent fluctuations (such as pulses or transient noise), which may require a system with a higher dynamic range. A low PAPR indicates that the signal is stable (such as a sine wave or steady-state noise). Based on these two indicators, the steps for judging signal strength are as follows: Measure RMS: Determine the average signal strength.

[0039] Measure Peak: Identify the maximum instantaneous intensity.

[0040] Calculate PAPR: If PAPR is close to 1.414 (sine wave), the signal strength is approximately equal to RMS; if PAPR is significantly higher, it is necessary to determine whether transient components need to be considered in conjunction with the application scenario.

[0041] 3) Dynamic distortion suppression and anti-interference mechanism The electromagnetic data acquisition unit integrates hardware amplitude limiting protection circuit and electromagnetic interference suppression filter to improve resistance to lightning interference; it adopts a cross-channel cross-verification mechanism to judge the consistency of multiple channel outputs within the same time window, eliminate interference pulses or instantaneous jump signals, and ensure high-reliability data output.

[0042] Specifically, firstly, a high-precision clock module is designed to generate a global synchronization signal, which serves as a unified time reference for all sampling channels. For example, a 10MHz clock signal can be generated using a high-stability TCXO crystal oscillator. After processing by a frequency divider circuit, a signal suitable for the sampling frequency (such as 1MHz) is obtained. This signal is then precisely distributed to the ADC modules of each channel using a low-jitter signal distributor, ensuring that the ADCs of each channel start sampling synchronously within the same time window, thus achieving consistency in sampling time.

[0043] Secondly, in each sampling period, each channel ADC converts the acquired analog signal into a digital signal and temporarily stores it in its respective buffer. After completing a time window sampling, the data comparison module (e.g., implemented by an FPGA) is activated to read the sampled data within the corresponding time window from each channel buffer and compare them one by one. The comparison method is to calculate the difference value (e.g., absolute difference) between the data of each channel and determine whether these difference values ​​are within a preset threshold range (e.g., 10 sampling units). If the difference value exceeds the threshold, the corresponding channel output is considered inconsistent.

[0044] Finally, the inconsistent channel data are further analyzed, and statistical analysis methods (such as calculating the mean and variance) are used to determine whether there are interference pulses or instantaneous jump signals. If the statistical quantity of a certain channel data is abnormal (such as excessive variance), the channel is identified as being interfered with. At this time, a data fusion algorithm (such as weighted average) is used to process the data of the interfered channel with other normal channel data to obtain more reliable output results, and the interference information is recorded for subsequent analysis and optimization.

[0045] 4) Zero-point calibration linkage module After each gain switch, the corresponding channel drift offset stored in the drift calibration unit will be reread and used in the drift calibration algorithm to ensure that each gain channel can maintain zero-point consistency under different operating conditions, and prevent signal distortion caused by offset mismatch during range switching.

[0046] (iv) Drift Calibration Unit This is used to perform drift calibration on the electromagnetic data of the electromagnetic data acquisition unit. Calibration is performed in static reference mode at the start of flight; during flight, it switches to dynamic reference mode to perform adaptive calibration of the real-time data stream based on a sliding window. The specific steps are as follows: 1. Static offset sampling initialization After the acquisition device is started, it enters the "static offset sampling initialization" stage. A simulated short circuit is used through the input channel to isolate the receiving coil signal. The receiving front-end acquisition circuit acquires the static output voltage over a period of time and calculates the initial average value. This initial offset value is stored in the memory for initial calibration reference during the early stages of flight. Specifically: 1) Multi-source triggering: Before the drone takes off, the data acquisition device can start the calibration action in a semi-automatic or fully automatic manner by pressing a physical button on the drone or by sending a command remotely (manual method: pressing a physical button on the drone by ground personnel; remote method: sending a command through the flight control system to trigger automatically). This reduces the cost of manual intervention and is especially suitable for multiple repetitive flight missions or surveys in extreme environments.

[0047] 2) Input switching: By using an analog switch or analog multiplexer, the input of the electromagnetic data acquisition unit can be switched from "receiving coil channel" to "internal short circuit" or "known reference circuit", effectively shielding all external geological signal interference.

[0048] Among them, internal short circuit: makes the voltage at the input terminal of the op-amp return to zero, only reflecting the zero bias of the system itself; known reference circuit: forms a controlled reference through virtual ground or low potential reference point.

[0049] This structure enables electrical isolation conditions for the device to sense its own offset, ensuring that the device only senses the offset it generates, thus providing a basis for accurate calibration.

[0050] 3) Acquiring Static Offset: Immediately after input switching, the static offset (including amplifier zero drift, thermal noise, ground potential changes, etc.) of the current sampling channel is sampled at multiple points, and the results are statistically modeled. This offset can be considered as:

[0051] in, This is the static offset. This is the op-amp input offset. Voltage changes caused by temperature drift For system reference potential fluctuation, These are transient noises, and all of them come from the data acquisition module ADC.

[0052] Sampling employs a high-resolution ADC and a filtered averaging algorithm to ensure stable and usable sampled values. After isolating external signals, static drift data such as the overall amplifier offset and thermal noise are acquired and recorded in real time. At this point, there is no receiving coil signal input, and the output voltage is the offset caused by the op-amp and ambient temperature. This process ensures accurate measurement of the system's inherent offset, providing an accurate reference for subsequent drift compensation.

[0053] 4) Offset storage: The final sampled offset is written to a local non-volatile memory (such as FLASH or EEPROM) and saved as the "zero reference value" of the current acquisition cycle, and associated with the timestamp and ambient temperature record value; multiple drift offset archives are supported, which facilitates dynamic backtracking and version comparison.

[0054] 2. Data calibration based on two modes After static offset sampling initialization, normal data acquisition is performed, i.e., electromagnetic data is received, and the acquired electromagnetic data is calibrated based on the drift offset, thereby achieving real-time drift cancellation and significantly improving the measurement accuracy and stability of the sensor under long-term operation or environmental changes.

[0055] A mechanism for fusion and switching between static and dynamic reference modes was designed. At the beginning of flight, the static reference mode based on static offset is used first for calibration. During flight, the dynamic reference mode based on dynamic offset is switched for calibration according to factors such as real-time noise level, attitude change, and temperature change.

[0056] (1) Calibration based on static reference mode of static offset Use static offset Calibration is performed, expressed by the formula:

[0057] in, The collected value is at time t, i.e., the real-time electromagnetic data. This is the calibrated electromagnetic data.

[0058] (2) Calibration based on dynamic reference mode of dynamic offset A sliding window is used to adaptively calculate the dynamic offset, and the dynamic offset is then used for calibration. Specifically: The receiving module performs sliding window statistical processing on the real-time data stream. Assume the collected value at time t is... The window is composed of measurements taken at the first N time points: ,...,

[0059] If there is no significant excitation response in this window (the excitation gap can be detected by combining the trigger signal window or setting a threshold), the dynamic offset is automatically calculated as the zero-point offset estimate for the current time period. The dynamic offset is expressed by the formula:

[0060] Dynamic calibration of real-time signals is performed based on dynamic offset:

[0061] If the device is detected to be in the excitation response zone (such as the electromagnetic pulse disturbance zone), calibration is paused to avoid weakening the signal itself.

[0062] The sliding window width N can be adaptively set according to the vibration characteristics of the flight platform and the signal period; it supports extreme value removal preprocessing of the filtering window to improve the ability to resist transient noise; the sliding calibration module is embedded in a low-power MCU or FPGA to ensure the real-time processing and energy consumption control of the device.

[0063] The sliding window adaptive method is simple to implement, has low computational cost, and is suitable for the real-time and stability requirements of flight platforms. It can take into account both the calibration of static reference and the dynamic update of micro offsets during flight, making it particularly suitable for long-duration UAV flight missions.

[0064] Example 2 One embodiment of the present invention provides a semi-airborne transient electromagnetic data acquisition method for real-time calibration of data drift. The method involves using a UAV carrying the semi-airborne transient electromagnetic data acquisition device provided in Embodiment 1 to acquire and calibrate electromagnetic data in real time. The specific steps during UAV flight are as follows: By using a transient electromagnetic hollow induction coil installed in the drone's coil storage compartment, the system receives secondary induction signals generated by the ground transmitter and performs adaptive gain control based on the signal strength to obtain real-time electromagnetic data. Two modes, static reference mode and dynamic reference mode, are used to perform drift calibration on real-time electromagnetic data to obtain calibrated electromagnetic data. During flight, the tilt angle and acceleration data fed back by sensors in the coil storage compartment are used to monitor the swing amplitude and frequency of the coil in real time, and to adjust and control the flight attitude.

[0065] Example 3 One embodiment of the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0066] Example 4 In one embodiment of the present invention, a non-transitory computer-readable storage medium is provided for storing computer instructions. When the computer instructions are executed by a processor, they realize the aforementioned semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0067] Example 5 One embodiment of the present invention provides an electronic device, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform a semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift.

[0068] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0069] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1The steps of the function specified in one or more boxes.

[0070] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift, characterized in that, This includes setting up the flight control unit, electromagnetic data acquisition unit, and drift calibration unit on the drone: The electromagnetic data acquisition unit receives secondary induction signals generated by the ground transmitter through a transient electromagnetic hollow induction coil installed in the UAV coil storage compartment, and performs adaptive gain control based on the signal strength to obtain real-time electromagnetic data. The flight control unit monitors the swing amplitude and frequency of the coil in real time based on the tilt angle and acceleration data fed back by the sensors in the coil storage compartment, and performs flight attitude adjustment and control. The drift calibration unit uses a static reference mode to calibrate real-time electromagnetic data at the beginning of flight; during flight, it switches to a dynamic reference mode to perform adaptive calibration of real-time electromagnetic data based on a sliding window.

2. The semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift as described in claim 1, characterized in that, The drone includes a hollow frame, a power system, and a coil storage compartment. The hollow frame is equipped with multiple arms, each with a power system at its end. The hollow frame has a coil storage compartment in the middle to house transient electromagnetic hollow induction coils. The power system includes a coaxially distributed rotor shaft, an insulated wing, and a double-layer motor; the flight attitude adjustment and control is achieved by adjusting the speed and direction of the coaxial double-layer motor to fine-tune the flight attitude in real time and counteract the oscillation of the receiving coil.

3. The semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift as described in claim 1, characterized in that, The transient electromagnetic hollow induction coil adopts a split design. The coil shell and the top cover are connected and fixed by a latch. The internal coil can be replaced with coils of different numbers of turns and materials according to the detection requirements. By adjusting the resistance and inductance of the coil, the damping ratio of the coil is optimized. By optimizing the inductance and distributed capacitance of the coil, the resonant frequency of the coil is set above the acceleration inflection point.

4. The semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift as described in claim 1, characterized in that, The adaptive gain control based on signal strength is achieved by detecting the peak value and root mean square value of the sampled signal in the receiving channel in real time, determining the current signal strength level, and then dynamically switching between several multi-stage variable gain amplifiers.

5. A semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift as described in claim 1, characterized in that, The static reference mode simulates a short circuit in the input channel to isolate the receiving coil signal. The receiving front-end acquisition circuit collects the static output voltage over a period of time and uses it as a static offset for data calibration in the early stages of flight.

6. The semi-airborne transient electromagnetic acquisition device for real-time calibration of data drift as described in claim 1, characterized in that, The dynamic reference mode continuously collects the measurement values ​​of the receiving coil at N times according to the preset sliding window width N, forms a sliding window, calculates the average measurement value within the sliding window as a dynamic offset, and uses it for data calibration of the current sliding window.

7. A semi-airborne transient electromagnetic acquisition method for real-time calibration of data drift, characterized in that, The specific steps during the drone flight process are as follows: Electromagnetic data is collected and calibrated in real time using a semi-airborne transient electromagnetic data acquisition device as described in any one of claims 1-6 carried on a drone. By using a transient electromagnetic hollow induction coil installed in the drone's coil storage compartment, the system receives secondary induction signals generated by the ground transmitter and performs adaptive gain control based on the signal strength to obtain real-time electromagnetic data. Two modes, static reference mode and dynamic reference mode, are used to perform drift calibration on real-time electromagnetic data to obtain calibrated electromagnetic data. During flight, the tilt angle and acceleration data fed back by sensors in the coil storage compartment are used to monitor the sway amplitude and frequency of the coil in real time, and to adjust and control the flight attitude.

8. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the semi-airborne transient electromagnetic acquisition method for real-time calibration of data drift as described in claim 7.

9. A non-transitory computer-readable storage medium, characterized in that, The non-transient computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement a semi-airborne transient electromagnetic acquisition method for real-time calibration of data drift as described in claim 7.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform a semi-airborne transient electromagnetic acquisition method for real-time calibration of data drift as described in claim 7.

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