A magnetic induction intensity measurement method applied to an unmanned aeromagnetic geophysical flight platform

Abstract

The application discloses a magnetic induction intensity measuring method applied to an unmanned aeromagnetic geophysical exploration flight platform, and the method comprises the following steps: selecting a measured point for installing a probe rod on the flight platform, acquiring intrinsic magnetic induction intensity distribution characteristics of the measured point at different directions and different distances in a static state through static measurement; acquiring intrinsic magnetic induction intensity gradient change characteristics of the measured point at different distances and different directions in a dynamic change process from static engine-off to in-flight and then to engine-off on the ground through dynamic measurement; and comprehensively evaluating results of the static measurement and the dynamic measurement to determine the probe rod installation position and the probe rod length. Thus, the magnetic induction intensity measuring method applied to the unmanned aeromagnetic geophysical exploration flight platform can be measured anywhere and is free from site constraints.

Description

Technical Field

[0001] This invention belongs to the field of airborne geophysical exploration technology, and in particular relates to a method for measuring magnetic induction intensity applied to an unmanned airborne magnetophysical exploration flight platform. Background Technology

[0002] Airborne magnetic surveying is one of the important methods in airborne geophysical exploration. Small unmanned airborne magnetic surveying platforms are increasingly widely used in airborne magnetic surveying due to their low operating cost, high mobility, and relatively simple logistical support. Currently, a rigid frame suspension modification scheme is commonly used in UAV airborne magnetic surveying: the airborne magnetic probe is usually fixed to one end of a probe rod, extending a certain distance outside the fuselage, while the other end of the probe rod is fixed to the fuselage of the flight platform; this fixed position is the probe rod installation point. Determining the installation position and extension distance of the probe rod is a key aspect of UAV modification.

[0003] Traditional measurement methods place stringent requirements on the measurement site to accurately determine probe length. According to aeromagnetic standards, the measurement site must have a calm magnetic field and minimal human interference. The site gradient must be such that the magnetic field variation within a 2m radius of the probe does not exceed half the design mean square error (total accuracy)—extremely demanding requirements. In field production environments, these conditions are difficult to meet, hindering the on-the-spot measurement and use of small unmanned aerial vehicles (UAVs). Overcoming the limitations of the site requirements and enabling small UAVs to measure intrinsic magnetic induction intensity distribution characteristics in field production environments is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This invention aims to provide a method for measuring magnetic flux density on unmanned aerial magnetic geophysical exploration platforms, enabling on-site measurement, overcoming site constraints, and providing accurate and reliable results. This invention considers the differences in the intrinsic magnetic flux density distribution characteristics at the probe installation point between the stationary and flight states of the flight platform, and designs a measurement scheme combining static and dynamic measurements. This overcomes the limitations imposed by site gradients on the measurement, making it possible for UAVs to measure intrinsic magnetic flux density in field production environments.

[0005] This invention provides a method for measuring magnetic induction intensity applied to an unmanned aerial magnetic geophysical exploration flight platform. The method includes: determining a test point on the flight platform for mounting a probe, wherein one end of the probe is used to mount an aerial magnetic probe and extends outside the aircraft by a predetermined distance, and the other end of the probe is fixed to the test point; performing static measurement on the test point: fixing a first magnetometer probe at the origin of the measurement site, taking any one of multiple measurement directions as the starting direction, moving the flight platform along the starting direction to gradually move the test point away from the origin from near to far, recording the first magnetic induction intensity value measured by the first magnetometer probe at different distances, and simultaneously recording the magnetic diurnal variation value measured by a second magnetometer probe set away from the measurement site; rotating the flight platform to the next measurement direction and repeating the above measurement until static measurement in all measurement directions is completed; and performing dynamic measurement on the test point: moving the flight platform... The flight platform is fixed at the take-off and landing point. A magnetometer probe is placed at the measured point, and the second magnetic induction intensity value measured by the magnetometer probe is recorded in three states: stationary, hovering in the air, and landing and shutting down. The distance between the magnetometer probe and the measured point is changed and the recording is repeated until the change in the second magnetic induction intensity value in the three states tends to a fixed value. The flight platform is rotated to the next measurement direction and the above measurement is repeated until dynamic measurement in all measurement directions is completed. Based on the static measurement data, the first minimum distance from the measured point to the probe is determined when the magnetic induction intensity direction difference of the measured point in the stationary state is less than a preset direction difference threshold. Based on the dynamic measurement data, the second minimum distance from the measured point to the probe is determined when the change in magnetic induction intensity of the measured point in the flight platform tends to a fixed value during take-off and landing. Based on the first minimum distance and the second minimum distance, the installation position and length of the probe rod are determined.

[0006] In some embodiments of the present invention, the gradient change of the continuous recording of the magnetic diurnal variation at the measurement site is no greater than 1 nT / min; the overall mass of the flight platform is less than 100 kg, and the fuselage is mainly made of non-magnetic materials; the first magnetometer probe and the second magnetometer probe are respectively from an airborne magnetometer, the step response rise time of the airborne magnetometer is no greater than 1 s, the probe directional difference is no greater than 1.0 nT, and the sampling rate is no less than 2 times / second; the bracket for fixing the magnetometer probe is made of completely non-magnetic material.

[0007] In some embodiments of the present invention, the plurality of measurement directions include eight directions centered on the origin: north, northeast, east, southeast, south, southwest, west, and northwest, corresponding to 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, respectively. Rays are drawn along each measurement direction from the origin within the measurement site. The length of each ray is greater than 1.5 times the maximum length of the flight platform. A distance marker is set on each ray at preset step intervals. In the static measurement, the nose of the flight platform is aligned with the current measurement direction, starting from the position where the measured point coincides with the origin, and moving away from the origin step by step according to the preset step interval. Optionally, the preset step interval is greater than or equal to 0.3 meters and less than or equal to 0.7 meters.

[0008] In some embodiments of the present invention, the static measurement further includes: when the bracket fixing the first magnetometer probe causes the measured point to not coincide with the origin, in the last measurement direction before the bracket needs to be moved, after the magnetic field stabilizes, recording the first magnetic induction intensity value measured by the first magnetometer probe and the magnetic diurnal variation value measured by the second magnetometer probe; moving the bracket to a designated position, after the magnetic field stabilizes, recording the first magnetic induction intensity value measured by the first magnetometer probe and the magnetic diurnal variation value measured by the second magnetometer probe again; and normalizing the static measurement data in each measurement direction after moving the bracket based on the values ​​recorded before and after the movement, so as to eliminate the error caused by moving the bracket.

[0009] In some embodiments of the present invention, the second magnetometer probe is placed at a location far from the measurement site, and the distance between the location and the measurement site is such that the magnetic field does not change significantly when people are active in the measurement site; before starting the static measurement, it is determined whether the trend of change of the magnetic diurnal variation curve and the magnetic field curve of the first magnetometer probe at the origin is stable and consistent. If so, the measurement is started.

[0010] In some embodiments of the present invention, during the dynamic measurement, the center position of the flight platform is on the same vertical line as the origin at the take-off and landing point during each take-off and landing; taking the initial position of the measured point as the zero point, a distance marker is set outward along the measurement direction at preset steps; the flight platform hovers at a preset height directly above the origin in the hovering state; when there are multiple measured points, a magnetometer probe with the same number as the measured points is set, and each magnetometer probe corresponds one-to-one with each measured point, so as to simultaneously observe the magnetic induction intensity change characteristics of all measured points.

[0011] In some embodiments of the present invention, determining the first minimum distance based on static measurement data includes: subtracting the corresponding magnetic diurnal variation value from the first magnetic flux density value measured by the first magnetometer probe at each distance to obtain the magnetic flux density difference at each measurement direction and distance; for the same distance, taking the difference between the maximum and minimum values ​​of the magnetic flux density differences at each measurement direction as the direction difference of the measured point at that distance; when the direction difference is less than a preset direction difference threshold, determining the distance corresponding to the direction difference as the first minimum distance. Optionally, the preset direction difference threshold is 1 nT.

[0012] In some embodiments of the present invention, determining the second minimum distance based on dynamic measurement data includes: subtracting the second magnetic induction intensity value measured by the magnetometer probe during hovering from the average value of the second magnetic induction intensity value measured by the magnetometer probe before takeoff and after landing, to obtain the change in magnetic induction intensity at each measurement direction and at each distance; when the change in magnetic induction intensity at a distance tends to a fixed value in all measurement directions, the distance is determined as the second minimum distance.

[0013] In some embodiments of the present invention, determining the installation position and length of the probe rod based on the first minimum distance and the second minimum distance includes: determining the larger of the first minimum distance and the second minimum distance as the minimum length of the probe rod; when the flight platform is equipped with multiple aeromagnetic probes, determining multiple test points equal to the number of aeromagnetic probes, and performing the static measurement and the dynamic measurement on each test point to determine the probe rod length corresponding to each test point.

[0014] Therefore, the method provided by this invention combines static and dynamic measurements to examine the intrinsic magnetic induction intensity distribution characteristics of the probe installation location points in both static and flight states of the flight platform. It eliminates errors caused by diurnal variations and support movement through synchronous observation and normalization of magnetic diurnal variations. The measurement process is insensitive to changes in site gradient; it can be implemented as long as the site is flat and open, the magnetic field is calm, and human interference is minimal. This eliminates the stringent requirements of traditional measurement methods regarding site gradients, making it possible for small unmanned aerial magnetic geophysical exploration platforms to measure intrinsic magnetic induction intensity distribution characteristics anywhere in field production environments. The obtained magnetic induction intensity distribution data at the measured points can provide a scientific basis for determining the probe installation location and extension distance, thereby providing strong technical support for the equipment integration and UAV modification work of aerial magnetic surveying. Attached Figure Description

[0015] Figure 1A This is an exemplary flowchart of the magnetic induction intensity measurement method of the present invention applied to an unmanned aerial magnetic geophysical exploration flight platform;

[0016] Figure 1B This is a schematic diagram of the static measurement site marking method of the present invention;

[0017] Figure 2 This is a schematic diagram showing the positional relationship between the origin probe, the flight platform, and the ground marker at the zero point position in the 135° direction of this invention;

[0018] Figure 3 This is a schematic diagram showing the positional relationship between the flight platform and the origin probe when the measured point in the 135° direction is 0.5 meters away from the origin.

[0019] Figure 4 This is a schematic diagram showing the positional relationship between the flight platform and the origin probe when the measured point in the 135° direction is 2.5 meters away from the origin.

[0020] Figure 5 This is a schematic diagram showing the positional relationship between the flight platform and the support before and after the moving probe support in the static measurement of this invention;

[0021] Figure 6 This is a schematic diagram showing the positional relationship between the magnetometer probe and the flight platform during dynamic measurement in this invention.

[0022] Figure 7 This is a schematic diagram showing the positional relationship between the magnetometer probe and the flight platform when the probe moves to 0.5 meters during the dynamic measurement of this invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0024] In one or more embodiments of this application, firstly, a test point for installing the probe is selected on the flight platform, and the intrinsic magnetic induction intensity distribution characteristics of the test point at different orientations and distances are obtained through static measurement. Secondly, the intrinsic magnetic induction intensity gradient change characteristics of the test point at different distances and directions are obtained through dynamic measurement during the dynamic process of the flight platform changing from stationary shutdown to flight and then landing shutdown. Finally, the results of static and dynamic measurements are comprehensively evaluated to determine the probe installation position and probe length.

[0025] Therefore, this invention addresses the difficulties of traditional measurement methods, which have stringent requirements for the gradient of the measurement site and are difficult to implement in field production environments. It proposes a measurement scheme that combines static and dynamic measurements and uses synchronous observation of magnetic and solar variations for correction. This eliminates the constraints of the site on measurement and makes it possible for small unmanned aerial magnetic geophysical exploration platforms to measure and use anywhere. It can provide strong technical support for the equipment integration and UAV modification work of aerial magnetic surveying.

[0026] Example 1

[0027] Please refer to Figure 1A This embodiment provides a method for measuring magnetic induction intensity applied to an unmanned aerial magnetic geophysical exploration platform, the method comprising:

[0028] Step 101: Determine the test point on the flight platform for mounting the probe.

[0029] One end of the probe rod is used to install an aeromagnetic probe and extends out of the aircraft body at a predetermined distance, while the other end of the probe rod is fixed to the point being measured.

[0030] Step 102: Perform static measurements on the measured point.

[0031] The process involves fixing a first magnetometer probe at the origin of the measurement site, using any one of multiple measurement directions as the starting direction, and moving the flight platform along the starting direction to gradually move the measured point away from the origin. The first magnetic induction intensity value measured by the first magnetometer probe at different distances is recorded, and the magnetic diurnal variation value measured by a second magnetometer probe located away from the measurement site is recorded simultaneously. The flight platform is then rotated to the next measurement direction, and the above measurements are repeated until static measurements in all measurement directions are completed.

[0032] Step 103: Perform dynamic measurement on the measured point.

[0033] The process involves fixing the flight platform at the takeoff and landing point, placing a magnetometer probe at the measurement point, and recording the second magnetic induction intensity value measured by the magnetometer probe in three states: stationary, hovering in the air, and landing and shutting down. The distance between the magnetometer probe and the measurement point is changed and the recording is repeated until the change in the second magnetic induction intensity value in the three states tends to a fixed value. The flight platform is rotated to the next measurement direction and the above measurement is repeated until dynamic measurement in all measurement directions is completed.

[0034] Step 104: Determine the first minimum distance based on static measurement data, and determine the second minimum distance based on dynamic measurement data.

[0035] Wherein, the first minimum distance is the minimum distance from the test point to the probe when the magnetic induction intensity direction difference of the test point is less than a preset direction difference threshold in a static state; the second minimum distance is the minimum distance from the test point to the probe when the change in magnetic induction intensity of the test point tends to a fixed value during the take-off and landing of the flight platform.

[0036] Step 105: Determine the installation position and length of the probe rod based on the first minimum distance and the second minimum distance.

[0037] In this embodiment, the small unmanned aerial magnetic geophysical exploration platform refers to a drone specifically designed for aerial magnetic geophysical exploration, with a fuselage weight of less than 100 kg, to facilitate the measurement of its intrinsic magnetic induction intensity distribution characteristics using this scheme. When performing aerial magnetic measurements, the aerial magnetic probe is typically mounted on the end of a probe rod extending a certain distance from the fuselage, while the other end of the probe rod is fixed to the flight platform. The flight platform can be stably parked at the test site under natural conditions and has certain modification potential: the platform cabin must have the necessary space to house the aerial geophysical measurement equipment, a DC28V power interface for external power supply, and a location outside the cabin away from the power source for installing the magnetometer probe, or an ideal probe installation position can be obtained by adding a probe rod.

[0038] The measured point refers to the selected installation location on the flight platform where the probe is fixed. The intrinsic magnetic flux density distribution characteristics to be measured in this scheme refer to the magnetic flux density distribution characteristics at the probe installation location, not the magnetic flux density distribution characteristics of the entire fuselage. The number of measured points corresponds to the number of probes installed on a flight platform. Before measurement, the probe installation location must be selected; this location is the measured point, such as the wingtip or nose of the flight platform. By calculating the static and dynamic measurement data of the measured point, the magnetic flux density variation characteristics of the measured point are obtained, thereby determining whether the measured point location is reasonable, and the probe extension distance or probe length.

[0039] The intrinsic magnetic flux density distribution refers to the distribution of magnetic flux density at a measured point under the influence of the platform's own magnetic field (intrinsic magnetic field) and its spatial orientation and distance. For locations where aeromagnetic probes can be installed, the intrinsic magnetic flux density spatially decreases from that point away from the aircraft, eventually approaching a fixed value. The intrinsic magnetic flux density distribution at the probe installation location differs significantly under different conditions, such as between a stationary and flying UAV. Different fuselage structures also cause variations in the intrinsic magnetic flux density distribution within localized areas; for example, the magnetic flux density near electronic control equipment and power units is generally significantly higher than at other locations.

[0040] Static measurement refers to the measurement of the intrinsic magnetic flux density of a test point at different orientations and distances when the flight platform is powered off, not running, and completely stationary. Its main purpose is to determine the minimum distance from the test point to the probe when the directional difference of the magnetic flux density at the test point is less than a preset directional difference threshold in a static state. This distance is one of the main scientific bases for determining the distance the probe should extend beyond the aircraft body when the flight platform is modified. Static measurement uses a fixed probe and a moving test platform to measure the magnetic flux density at the test point. For the selected test point, in actual operation, the probe extends beyond the aircraft body with the test point as its endpoint; therefore, only the planar magnetic flux density distribution at that point needs to be measured, and three-dimensional measurement is not required.

[0041] Dynamic measurement refers to the measurement of the intrinsic magnetic flux density gradient characteristics at different distances and directions from the probe during the dynamic process of the flight platform changing from a stationary shutdown to flight and then to landing shutdown. The main purpose is to determine the minimum distance from the probe to the measured point when the change in magnetic flux density at the measured point approaches zero or a fixed value during the shutdown process. Dynamic measurement uses a method of changing the probe position while keeping the flight platform's takeoff and landing points fixed to measure the magnetic flux density gradient at the measured point. If the probe is installed beyond the aforementioned minimum distance, the magnetic field generated by the flight platform's takeoff and landing can be considered to have no effect on the probe.

[0042] Magnetic diurnal variation refers to the natural changes in the Earth's magnetic field over time caused by factors such as solar activity. During measurement, this magnetic diurnal variation is superimposed on the intrinsic magnetic field of the flight platform, affecting the judgment of the magnetic induction intensity distribution characteristics at the measured point. Therefore, a second magnetometer is needed for diurnal variation observation, i.e., a second magnetometer probe. This probe should be placed far away from the measurement site, at a distance where the magnetic field does not change significantly when personnel are active at the measurement site. By subtracting the synchronous magnetic diurnal variation value from the measurement value of the origin probe, the influence of magnetic diurnal variation on the measurement results can be eliminated.

[0043] Directional difference refers to the difference in measurement results of the same magnetic field by a magnetometer probe under different orientations. In static measurements, for the same distance, the difference between the maximum and minimum values ​​of the magnetic induction intensity value and the magnetic diurnal variation value of the probe at the origin in each measurement direction is the directional difference of the measured point when the probe is at that distance from the measured point. According to current aeromagnetic standards, the directional difference should be less than 1 nT, therefore, the preset directional difference threshold can be taken as 1 nT.

[0044] Airborne magnetometers refer to high-precision magnetometers suitable for airborne magnetic measurements. This scheme uses at least two airborne magnetometers, with a step response rise time not exceeding 1 second, a probe directional difference not exceeding 1.0 nT, and a sampling rate not less than 2 times / second. The consistency requirement for the two devices is that the maximum change in measurement difference during continuous observation for 5 hours should be less than 0.5 nT. The peak-to-peak value of the envelope of local variations of a single magnetometer should be less than 0.1 nT within any 10 seconds.

[0045] A non-magnetic bracket refers to a bracket used to fix an aeromagnetic probe. It must be made entirely of non-magnetic material, with dimensions no larger than 0.5m × 0.5m × 0.25m, be lightweight and sturdy, and have multiple anchor points. A bracket made entirely of non-magnetic material will not generate an additional magnetic field around it, thus avoiding interference with the measurement results.

[0046] For a small UAV used for aeromagnetic surveying, the intrinsic magnetic flux density distribution at the probe mounting location must be measured before production. The intrinsic magnetic flux density at the mounting location generally decreases gradually from that location away from the aircraft, eventually approaching a fixed value. The intrinsic magnetic flux density distribution at the probe mounting location differs significantly under different conditions, such as when the UAV is stationary versus in flight. Different fuselage structures also cause variations in the intrinsic magnetic flux density distribution within localized areas; for example, the magnetic flux density near electronic control equipment and power units is generally significantly higher than at other locations. Based on the measurement results, technicians can determine whether the flight platform is suitable for aeromagnetic surveying and, accordingly, determine the probe length so that the probe can extend a certain distance away from the aircraft's magnetic field source.

[0047] The method provided in this embodiment determines the measurement point on the flight platform for mounting the probe, performs static and dynamic measurements on the measurement point, and determines a first minimum distance based on the static measurement data and a second minimum distance based on the dynamic measurement data. The installation position and length of the probe are then determined by combining the first and second minimum distances. This allows technicians to obtain magnetic field strength distribution data and maps of the measurement point on a plane, determining the installation position and extension distance of the probe, providing a scientific basis for equipment integration and UAV modification work in aeromagnetic surveying. Simultaneously, the measurement process only requires a flat and open site, a calm magnetic field, and minimal human interference. The impact of site gradient changes on the measurement scheme is limited, eliminating the stringent site requirements of traditional measurement methods where the magnetic field variation within a 2m radius space centered on the probe cannot exceed half of the design mean square error (total accuracy). This makes it possible for a small unmanned aeromagnetic geophysical surveying flight platform to measure the intrinsic magnetic field strength distribution characteristics anywhere in the field production environment.

[0048] In some embodiments of the present invention, the gradient change of the continuous recording of the magnetic diurnal variation of the measurement site is no greater than 1 nT / min; the overall mass of the flight platform is less than 100 kg, and the fuselage is mainly made of non-magnetic materials; the step response rise time of the airborne magnetometer is no greater than 1 s, the probe directional difference is no greater than 1.0 nT, and the sampling rate is no less than 2 times / second; the bracket for fixing the magnetometer probe is made of all non-magnetic materials.

[0049] Therefore, the measurement site is only required to retain the requirement that the gradient change of the continuous recording of the magnetic diurnal variation should not exceed 1 nT / min. The gradient change of the site has a limited impact on this measurement scheme, which greatly reduces the dependence of the measurement on the site and allows the measurement to be carried out in ordinary field sites. The restrictions on the overall mass of the flight platform, the fuselage materials, the performance of the magnetometer, and the material of the support structure ensure the consistency and reliability of the measurement data: the consistency requirements that the maximum change of the measurement difference between two magnetometers after 5 hours of continuous observation should be less than 0.5 nT and the peak-to-peak value of the envelope of the local change of a single magnetometer should be less than 0.1 nT within any 10 seconds ensure the comparability between the observation data of the origin probe and the diurnal variation probe, and provide an accuracy basis for subsequent difference correction.

[0050] In some embodiments of the present invention, the plurality of measurement directions include eight directions centered on the origin: north, northeast, east, southeast, south, southwest, west, and northwest, corresponding to 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, respectively. Rays are drawn along each measurement direction from the origin within the measurement site. The length of each ray is greater than 1.5 times the maximum length of the flight platform. A distance marker is set on each ray at preset step intervals. In the static measurement, the nose of the flight platform is aligned with the current measurement direction, starting from the position where the measured point coincides with the origin, and moving away from the origin step by step according to the preset step interval. Optionally, the preset step interval is greater than or equal to 0.3 meters and less than or equal to 0.7 meters.

[0051] The origin point refers to the reference point marked on the ground at the measurement site, used to fix the first magnetometer probe (origin probe). Eight measurement directions, evenly distributed at 45° intervals, cover the entire horizontal plane, comprehensively depicting the magnetic field strength distribution of the measured point in all directions. The ray length is greater than 1.5 times the maximum length of the flight platform, ensuring that the measured point can be moved to a sufficiently far distance where the intrinsic magnetic field strength decays to near a fixed value. Distance markers provide accurate positional references for the movement of the flight platform, ensuring the accuracy of measurement data at each distance.

[0052] Therefore, by systematically deploying measurement points in eight directions from near to far, the measurement data can fully reflect the variation of the intrinsic magnetic induction intensity of the measured point with azimuth and distance, providing a complete data foundation for calculating the directional difference at different distances, thus enabling accurate determination of the minimum distance at which the directional difference meets the aeromagnetic standard under stationary conditions.

[0053] In some embodiments of the present invention, the static measurement further includes: when the bracket fixing the first magnetometer probe causes the measured point to not coincide with the origin, in the last measurement direction before the bracket needs to be moved, after the magnetic field stabilizes, recording the first magnetic induction intensity value measured by the first magnetometer probe and the magnetic diurnal variation value measured by the second magnetometer probe; moving the bracket to a designated position, after the magnetic field stabilizes, recording the first magnetic induction intensity value measured by the first magnetometer probe and the magnetic diurnal variation value measured by the second magnetometer probe again; and normalizing the static measurement data in each measurement direction after moving the bracket based on the values ​​recorded before and after the movement, so as to eliminate the error caused by moving the bracket.

[0054] Normalization refers to the correction processing performed on measurement data to eliminate errors caused by moving the probe support. In static measurements, because the probe support occupies a certain amount of space, when the flight platform rotates around the origin, the probe support may hinder the measured point from approaching the probe in certain directions and at certain distances, making it impossible for the measured point to coincide with the origin. In this case, it is necessary to move the position of the probe support. During the movement, the probe orientation changes, and due to the probe's inherent directional difference, it will introduce some errors; the probe position will also change slightly, and due to the gradient of the ground, it will also introduce some errors. By recording the magnetic induction intensity values ​​of the origin probe and the magnetic diurnal variation before and after the support movement, the systematic deviation caused by the movement of the support can be obtained, and the measurement data in each direction after the support movement can be uniformly corrected.

[0055] Therefore, normalization eliminates the probe orientation error and site gradient error introduced by the forced movement of the support, ensuring the consistency and comparability of data in all eight measurement directions. This enables accurate and reliable static measurement results to be obtained even when the support has to be moved, and improves the adaptability of the measurement scheme to complex site conditions.

[0056] In some embodiments of the present invention, the second magnetometer probe is placed at a location far from the measurement site, and the distance between the location and the measurement site is such that the magnetic field does not change significantly when people are active in the measurement site; before starting the static measurement, it is determined whether the trend of change of the magnetic diurnal variation curve and the magnetic field curve of the first magnetometer probe at the origin is stable and consistent. If so, the measurement is started.

[0057] Therefore, the diurnal variation probe is placed far away from the measurement site, avoiding interference from the activities of measurement personnel and the movement of the flight platform, thus ensuring the purity of the magneto-diurnal variation data. The judgment of the stability and consistency between the magneto-diurnal variation curve and the magnetic field curve of the origin probe before the measurement begins ensures that the measurement is carried out during the period of magnetic field stability, thus ensuring the validity of the measurement data from the source and avoiding data distortion caused by measurement during periods of magnetic disturbance.

[0058] In some embodiments of the present invention, during the dynamic measurement, the center position of the flight platform is aligned vertically with the origin at each takeoff and landing point; using the initial position of the measured point as the zero point, a distance marker is set outward along the measurement direction at preset step intervals; the flight platform hovers at a preset height directly above the origin in an air-hovering state; when there are multiple measured points, a magnetometer probe with the same number as the measured points is set, with each magnetometer probe corresponding to each measured point to simultaneously observe the magnetic induction intensity change characteristics of all measured points. Optionally, the preset height is 50 centimeters.

[0059] Therefore, the center position of the flight platform is on the same vertical line as the origin at the take-off and landing point during each take-off and landing, ensuring that the measurement data of each measured point is obtained under the same flight state during dynamic measurement, which improves the comparability of data between different distances and directions; multiple probes correspond one-to-one with multiple measured points for simultaneous observation, so that dynamic data of all measured points can be obtained in one take-off and landing process, which not only ensures that the data of each measured point corresponds to the exact same flight state, but also significantly improves the measurement efficiency; the hovering height is set at 50 cm to simulate the actual magnetic field changes near the probe during the take-off and landing of the flight platform, making the measurement results closer to the actual aeromagnetic operation state.

[0060] In some embodiments of the present invention, determining the first minimum distance based on static measurement data includes: subtracting the corresponding magnetic diurnal variation value from the first magnetic flux density value measured by the first magnetometer probe at each distance to obtain the magnetic flux density difference at each measurement direction and distance; for the same distance, taking the difference between the maximum and minimum values ​​of the magnetic flux density differences at each measurement direction as the direction difference of the measured point at that distance; when the direction difference is less than a preset direction difference threshold, determining the distance corresponding to the direction difference as the first minimum distance. Optionally, the preset direction difference threshold is 1 nT.

[0061] Therefore, by correcting the difference between the measured value of the origin probe and the value of the magnetic diurnal variation, the influence of the magnetic diurnal variation over time on the static measurement data is eliminated, and the data measured at different times and in different directions are attributed to the same magnetic field reference. The difference between the maximum and minimum values ​​of the difference in each direction at the same distance is taken as the directional difference of that distance, which directly corresponds to the requirement in the current aeromagnetic standard that the directional difference should be less than 1 nT. Thus, the minimum distance that the probe extends out of the aircraft body in a static state can be scientifically and quantitatively determined.

[0062] In some embodiments of the present invention, determining the second minimum distance based on dynamic measurement data includes: subtracting the second magnetic induction intensity value measured by the magnetometer probe during hovering from the average value of the second magnetic induction intensity value measured by the magnetometer probe before takeoff and after landing, to obtain the change in magnetic induction intensity at each measurement direction and at each distance; when the change in magnetic induction intensity at a distance tends to a fixed value in all measurement directions, the distance is determined as the second minimum distance.

[0063] Therefore, by using the average value of the measurements taken before takeoff and after landing as a benchmark, and subtracting the measurement value during hovering, the influence of the flight platform's start-up and flight state on the magnetic field of the measured point is quantitatively characterized. When the changes in all measurement directions at a certain distance tend to a fixed value, it indicates that the influence of the magnetic field generated by the flight platform's takeoff and landing on the probe no longer changes with distance and direction beyond that distance. It can be considered that the magnetic field generated by the flight platform's takeoff and landing has no effect on the probe, thus scientifically determining the shortest distance of the probe under dynamic conditions.

[0064] In some embodiments of the present invention, determining the installation position and length of the probe rod based on the first minimum distance and the second minimum distance includes: determining the larger of the first minimum distance and the second minimum distance as the minimum length of the probe rod; when the flight platform is equipped with multiple aeromagnetic probes, determining multiple test points equal to the number of aeromagnetic probes, and performing the static measurement and the dynamic measurement on each test point to determine the probe rod length corresponding to each test point.

[0065] Therefore, by taking the larger value between the static and dynamic measurement results as the minimum probe length, the influence of the flight platform on the magnetic induction intensity measured by the probe can be eliminated in both static and dynamic states. This ensures that the modified aeromagnetic measurement system meets the aeromagnetic accuracy requirements throughout the entire process of ground parking, takeoff and landing, and flight. By measuring each point on the multi-probe platform and determining the probe length separately, the installation position of each probe has been rigorously verified, providing a complete technical basis for the integration of the multi-probe aeromagnetic system.

[0066] Example 2

[0067] This embodiment provides a method for measuring magnetic induction intensity applied to an unmanned aerial magnetic geophysical exploration platform, including the following steps:

[0068] The first step is measurement preparation. Select a flat, open measurement site with a calm magnetic field and minimal human interference, and confirm that the gradient change in the continuous magnetic diurnal variation record does not exceed 1 nT / min; prepare the small unmanned aeromagnetic geophysical exploration flight platform to be measured, at least two airborne magnetometers, and several non-magnetic supports for fixing the aeromagnetic probes; select the location where the probe rod will be installed as the measurement point, and if there are several measurement points, then each measurement point will need to be measured separately.

[0069] The second step is static measurement. Mark the origin, direction, and length on the ground. Fix the origin probe at the origin using a non-magnetic support, and place the diurnal variation probe at a location far from the measurement site. Turn on the diurnal variation observation system and the origin probe's recording system. If the diurnal variation magnetic field curve and the probe's magnetic field curve at the origin show a stable trend, begin the measurement. Using a certain direction as the starting direction, align the flight platform's nose with that direction and ensure the measured point coincides with the origin. Record the magnetic induction intensity values ​​of the origin probe and the diurnal variation record under stable magnetic field conditions. Keeping the nose direction unchanged, gradually move the flight platform further away according to a preset step size, recording the measurement values ​​at each distance. Rotate the flight platform to the next direction and repeat the above process. One rotation completes the static measurement of one measured point. If the support needs to be moved during the measurement process because it obstructs the coincidence of the measured point and the origin, normalization processing is performed.

[0070] The third step is dynamic measurement. A fixed point is set as the origin within the site. The center of the flight platform is aligned vertically with the origin at each takeoff and landing. A certain direction is selected as the starting direction, and the initial position of the measured point is recorded as the zero point. A mark is made at preset steps outward, and each probe is placed at the corresponding zero point position of each measured point. The magnetic induction intensity values ​​measured by each probe are recorded sequentially in three states: the flight platform is stationary (before takeoff), hovering at a preset height directly above the origin (while hovering), and landing at the origin (after landing). Subsequently, the distance of each probe relative to the measured point is continuously changed according to the ground marks, and the measurement values ​​in the three states are recorded repeatedly. When the observed value changes tend to a fixed value, the measurement in one direction is completed. The flight platform is rotated to the next direction to continue the measurement. After one rotation, the dynamic measurement of all measured points is completed.

[0071] The fourth step is static data processing. The magnetic flux density value measured at the origin probe at each distance is subtracted from the corresponding magnetic diurnal variation value to obtain the difference in each direction and distance. Laterally, the differences in each direction at the same distance are compared, and the maximum value minus the minimum value represents the directional difference between the probe and the measured point at that distance. For each direction after moving the probe position, the data is first normalized and corrected before being compared. The minimum distance corresponding to a directional difference less than 1 nT is the first minimum distance in the static state.

[0072] The fifth step is dynamic data processing. The average magnetic field strength before takeoff and after landing is subtracted from the magnetic field strength during hovering to obtain the change in magnetic field strength in each direction and at each distance. When the change in magnetic field strength in all directions at a certain distance tends to a fixed value, that distance is the second minimum distance under dynamic conditions. The results of both static and dynamic measurements are comprehensively evaluated, and the larger of the first and second minimum distances is taken as the minimum length of the probe, ultimately determining the probe's installation position and length.

[0073] This embodiment has the following advantages:

[0074] (1) The intrinsic magnetic induction intensity distribution characteristics to be measured in this scheme refer to the magnetic induction intensity distribution characteristics at the probe installation position, not the magnetic induction intensity distribution characteristics of the entire machine body. The measurement target is clear and the workload is controllable. By combining static and dynamic measurements, the first minimum distance with a directional difference of less than 1nT in the static state and the second minimum distance with a magnetic induction intensity change tending to a fixed value in the dynamic state are determined respectively. The probe length is determined by both static and dynamic measurements, and the measurement results are scientific and reliable.

[0075] (2) In addition to being consistent with the requirements of the aeromagnetic specification in the continuous recording of the gradient change of the magnetic diurnal variation, the gradient change of the measurement site has a limited impact on this measurement scheme. As long as the site is flat and open, the magnetic field is calm, and human interference is minimal, it can be done without the constraints of the site on the measurement. This makes it possible for UAVs to measure the intrinsic magnetic induction intensity in the field production environment, which is conducive to the measurement and use of small UAVs anywhere.

[0076] Example 3

[0077] This embodiment uses the wingtip position of the flight platform as the measurement point, combined with... Figures 1B to 7 The measurement method and data processing procedure of the present invention will be described in detail below.

[0078] (1) Standard procedures for static measurement. Mark the site and place the probe and flight platform. The surveyors determine the origin point and, using the origin point as the center, set eight directions: north, northeast, east, southeast, south, southwest, west, and northwest, as 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°. Along these eight directions, starting from the origin point, draw rays on the measurement site. The ray length should ideally be greater than 1.5 times the maximum length of the aircraft. Mark a point every 50 cm along each ray. The ground marking effect is as follows: Figure 1B As shown. The origin probe is fixed at one corner of the non-magnetic support, which coincides with the origin. The flight platform uses any one of the eight directions as the measurement starting point, with the nose of the aircraft aligned with that direction, and the measured point and the origin position are made as coincident as possible.

[0079] Turn on the diurnal variation observation system and observe whether the diurnal variation is stable; turn on the recording system of the origin probe and observe whether the recorded curve of the origin probe is stable; if the diurnal variation magnetic field curve and the magnetic field curve of the probe at the origin have a stable and consistent trend, then measurement can begin. Taking a probe head pointing at 135° as an example, the positional relationship between the measured point and the probe in the marked area is as follows: Figure 2 As shown. After the magnetic field changes at the origin and the wingtip position stabilize, data is recorded. A distance of 0 indicates that the wingtip position coincides with the origin. With the probe position fixed, starting from the origin, keeping the nose pointing at 135°, the flight platform is gradually moved further away in 0.5-meter increments. When the wingtip is 0.5 meters from the origin, the positions of the flight platform and the probe are as follows. Figure 3 As shown; the magnetic induction intensity values ​​of the origin probe and the magnetic diurnal variation were recorded when the wingtip was 1 meter, 1.5 meters, 2 meters, and 2.5 meters away from the origin. The orientation of the flight platform and the origin probe on the ground at the furthest distance is shown in the figure. Figure 4 As shown. Thus, all measurements of the wingtip position in one direction are completed, and the measurement results are shown in Table 1.

[0080] Origin probe (nT) 43.1 41.0 40.8 40.5 40.6 40.6 Magnetoheliodynamic Variation (nT) 38.1 38.3 38.3 38.0 38.0 37.9

[0081] Table 1-135° Direction: Magnetic Induction Intensity of Origin Probe and Magnetic Diurnal Variation at Different Distances from the Origin at the Wingtip.

[0082] Move the flight platform clockwise, pointing the nose towards the 180° direction, while simultaneously aligning the wingtip with the origin again. Record the magnetic induction intensity values ​​from the origin probe and the diurnal variation record under stable magnetic field conditions. Then, continuing in 0.5-meter increments, gradually move the flight platform away from the origin along the 180° ray direction until the measured point is 2.5 meters from the origin, completing the 180° measurement of the wingtip measured point. Afterward, rotate the flight platform, pointing the nose towards 225°, 270°, 315°, 0°, 45°, and 90° respectively, measuring the magnetic induction intensity values ​​at different distances from the origin to the wingtip in each direction. Once all eight directions have been measured, the measurement of one measured point is complete. For multiple measured points, the static measurement method is the same as the measurement method for the wingtip measured point.

[0083] (2) Normalized measurement of static measurements. Taking the wingtip position as an example, during the measurement process, when the nose rotates to 315°, if the probe support position remains unchanged, the wingtip position of the flight platform will not completely coincide with the origin probe. Therefore, it is necessary to move the probe support, such as... Figure 5As shown in Table 2. The specific measurement method is as follows: In the last measurement direction before moving the probe support, after the magnetic field stabilizes, accurately record the magnetic induction intensity value, including both the original probe value and the magnetic diurnal variation value; then, the measurement personnel move the probe support to the designated position, and after the magnetic field stabilizes, record the magnetic induction intensity values ​​of the original probe and the magnetic diurnal variation value again. The recorded results are shown in Table 2. Because the probe itself has a certain directional difference, and the measurement site has a certain gradient, the error must be eliminated through normalization after changing the original position of the probe.

[0084] Origin probe (nT) 40.2 38.1 Magnetoheliodynamic Variation (nT) 37.4 37.4

[0085] Table 2 - Magnetic induction intensity of normalized operation records

[0086] (3) Dynamic Measurement. A fixed point is set up in the field and marked as the origin. The center position of the flight platform is on the same vertical line as the origin at the take-off and landing point for each take-off and landing. Taking the direction of due south 180° as the starting direction, the initial position of the measured point is recorded as the zero point, and a mark is made every 0.5 meters outward. The probe is placed at the zero point position. The number of marks and probes corresponds to the number of measured points. Taking the wing and nose as two measured points as examples, the positional relationship between each probe and the flight platform is as follows: Figure 6 As shown. With the flight platform stationary, record the magnetic induction intensity values ​​measured by each probe in the initial state; then start the flight platform, requiring it to hover 50 cm directly above the origin. After the magnetic induction intensity values ​​stabilize, record the magnetic induction intensity values ​​measured by each probe; the flight platform lands at the origin, and after the magnetic induction intensity values ​​stabilize, record the magnetic induction intensity values ​​measured by each probe. This completes the measurement of each measured point at the zero point along the 180° direction. Following the ground markings, keeping the flight platform position unchanged, move the probe position to a location 0.5 meters away from the measured point, as shown. Figure 7 As shown, the magnetic induction intensity values ​​recorded by each probe were recorded before takeoff, during hovering, and after landing. Subsequently, the probes were placed at 1 meter and 1.5 meters, and the magnetic induction intensity values ​​in the three states were recorded again. The magnetic induction intensity values ​​at various distances in the 180° direction at the wingtip position are shown in Table 3. Then, following the measurement method in the 180° direction, the magnetic induction intensity values ​​of the measured points on the flight platform were measured successively at different distances in the remaining seven directions (225°, 270°, 315°, 0°, 45°, 90°, 135°), in the three states, respectively. At this point, the dynamic measurement of all measured points was completed.

[0087] Before takeoff 114.7 202 212 204 Hovering 107 193 207 202 After landing 115 201 210 205

[0088] Table 3 - Dynamic Magnetic Induction Intensity Values ​​(nT) at Wingtip Positions in the 180° Direction

[0089] (4) Static data processing. Taking the data obtained from the measurement point at the 135° wingtip position as an example, the magnetic induction intensity value of the origin probe measured at each distance is subtracted from the corresponding magnetic diurnal variation value; the measurement data of other directions of the measurement point are calculated and filled in, and the data are observed laterally to obtain the difference between the origin probe and the magnetic diurnal variation in each direction at different distances; the maximum value of the difference in each direction at the same distance minus the minimum value is the direction difference of the measurement point when the probe is at that distance from the measurement point. For the data in each direction at 315°, 0°, 45°, and 90° after moving the probe position, they are corrected according to the normalized measurement results in Table 2 before being compared. The processing results show that the directional difference is 10.9 nT at a distance of 0 meters, 3.6 nT at 0.5 meters, 1.3 nT at 1 meter, 0.9 nT at 1.5 meters, 0.5 nT at 2 meters, and 0.4 nT at 2.5 meters. According to current aeromagnetic standards, the directional difference should be less than 1 nT. Therefore, under static conditions, the directional difference at a distance of 1.5 meters already meets the standard. Thus, if the probe is installed at the wingtip, the minimum probe length in a static state is 1.5 meters, i.e., the first minimum distance is 1.5 meters. Using the same processing method, the data measured at other test points were processed to obtain the shortest distances where the directional difference is less than 1 nT in a static state for each test point.

[0090] (5) Dynamic Data Processing. Taking the 180° direction as an example, the data measured at the wingtip position is processed by subtracting the magnetic induction intensity value during hovering from the average value of the magnetic induction intensity before takeoff and after landing to obtain the change in magnetic induction intensity at each direction and distance. Observing the data laterally, the distribution of the change in magnetic induction intensity in each direction at a certain distance can be obtained: when the distance is 1 meter, the change in the 180° direction tends to a fixed value, while the value in the 270° direction shows no obvious trend; when the distance is 2 meters, the change in the difference in magnetic induction intensity in each direction tends to a fixed value. Therefore, when installing the probe at the wingtip position, the minimum length of the probe under dynamic conditions should be 2 meters, that is, the second minimum distance is 2 meters.

[0091] (6) Comprehensive Evaluation. Combining the first minimum distance of 1.5 meters from the static measurement results and the second minimum distance of 2 meters from the dynamic measurement results, taking the larger value, it can be seen that if a probe is to be installed on the wingtip, the probe rod needs to be at least 2 meters long to simultaneously eliminate the influence of the flight platform on the magnetic induction intensity measured by the probe under both static and dynamic conditions. At this point, all measurements and data processing for the wingtip measurement point are complete. Other measurement points are processed in the same way.

[0092] This embodiment has the following advantages:

[0093] (1) Traditional measurement methods have strict requirements for the measurement site. Typically, the change in magnetic field within a 2m radius of the probe should not exceed 1 / 2 of the design mean square error (total accuracy). This requirement is not conducive to the on-the-spot measurement and use of small UAVs. This embodiment uses a static measurement method with a fixed probe and a moving platform, and a dynamic measurement method with a fixed take-off and landing point and a changed probe position. Combined with synchronous observation correction and normalization of magnetic and solar variations, the measurement results are not significantly affected by the site gradient. Accurate and reliable measurement data can be obtained in ordinary field sites, freeing the measurement from the constraints of the site.

[0094] (2) The static data processing method and dynamic data processing method given in this embodiment directly correspond to the requirements of the current aeromagnetic standard that the directional difference is less than 1nT and the requirement that the influence of the flight platform on take-off and landing tends to be stable. The criteria are clear and the operation is simple. The measured probe length can simultaneously eliminate the influence of the flight platform on the probe's magnetic induction intensity under static and dynamic conditions, providing a scientific basis for the equipment integration of aeromagnetic measurement and the modification of UAVs.

[0095] As used herein, the term "preferred" is meant as an example, illustration, or illustration. Any aspect or design described herein as "preferred" need not be construed as being more advantageous than other aspects or designs. Rather, the use of the term "preferred" is intended to present the concept in a specific manner. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusionary "or." That is, unless otherwise specified or clear from the context, "X uses A or B" naturally includes either of the permutations. That is, if X uses A; X uses B; or X uses both A and B, then "X uses A or B" is satisfied in any of the foregoing examples.

[0096] Furthermore, although this disclosure has been shown and described with respect to one or more implementations, equivalent variations and modifications will occur to those skilled in the art based on a reading and understanding of this specification and the accompanying drawings. This disclosure includes all such modifications and variations and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the aforementioned components (e.g., elements, etc.), the terminology used to describe such components is intended to correspond to any component (unless otherwise indicated) that performs the specified function of said component (e.g., is functionally equivalent to it), even if structurally not equivalent to the disclosed structure performing the functions in the exemplary implementations of this disclosure shown herein. Moreover, although specific features of this disclosure have been disclosed with respect to only one of several implementations, such features may be combined with one or more features of other implementations that may be desirable and advantageous for a given or particular application. Furthermore, with regard to the use of the terms “comprising,” “having,” “containing,” or variations thereof in the Detailed Description or claims, such terms are intended to be included in a manner similar to the term “including.”

[0097] In summary, the above embodiments are one implementation of the present invention, but the implementation of the present invention is not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made that deviate from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A method for measuring magnetic induction intensity applied to an unmanned aerial magnetic geophysical exploration platform, characterized in that, The method includes: The test point on the flight platform is determined for mounting a probe rod, wherein one end of the probe rod is used to mount an aeromagnetic probe and extends out of the aircraft body at a predetermined distance, and the other end of the probe rod is fixed to the test point; Static measurements are performed on the measured point: The first magnetometer probe is fixed at the origin of the measurement site. Taking any one of the multiple measurement directions as the starting direction, the measured point is gradually moved away from the origin by moving the flight platform in the starting direction. The first magnetic induction intensity value measured by the first magnetometer probe at different distances is recorded, and the magnetic diurnal variation value measured by the second magnetometer probe set away from the measurement site is recorded simultaneously. The flight platform is rotated to the next measurement direction and the above measurements are repeated until the static measurements in all measurement directions are completed. Dynamic measurements are performed on the measured point: the flight platform is fixed at the take-off and landing point, the magnetometer probe is placed at the measured point, and the second magnetic induction intensity value measured by the magnetometer probe is recorded in three states: stationary, hovering in the air, and landing and shutting down. The distance between the magnetometer probe and the measured point is changed and the recording is repeated until the change in the second magnetic induction intensity value in the three states tends to a fixed value. The flight platform is rotated to the next measurement direction and the above measurement is repeated until dynamic measurements in all measurement directions are completed. Based on static measurement data, the first minimum distance from the measured point to the probe is determined when the magnetic induction intensity direction difference of the measured point in a static state is less than a preset direction difference threshold. Based on dynamic measurement data, the second minimum distance from the measured point to the probe is determined when the change in magnetic induction intensity of the measured point during the take-off and landing of the flight platform tends to a fixed value. The installation position and length of the probe are determined based on the first minimum distance and the second minimum distance.

2. The method according to claim 1, characterized in that, The gradient change of the continuous recording of the magnetic diurnal variation at the measurement site is no greater than 1 nT / min; The overall weight of the flight platform is less than 100 kg; The first magnetometer probe and the second magnetometer probe are respectively from an airborne magnetometer. The step response rise time of the airborne magnetometer is no greater than 1 second, the probe direction difference is no greater than 1.0 nT, and the sampling rate is no less than 2 times / second. The bracket that holds the magnetometer probe is made of a completely non-magnetic material.

3. The method according to claim 1, characterized in that, The multiple measurement directions include eight directions centered on the origin: due north, northeast, due east, southeast, due south, southwest, due west, and northwest, corresponding to 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, respectively. Within the measurement site, rays are drawn along each measurement direction starting from the origin. The length of each ray is greater than 1.5 times the maximum length of the flight platform. A distance marker is set on each ray at preset step intervals.

4. The method according to claim 3, characterized in that, In the static measurement, the nose of the flight platform is aligned with the current measurement direction, and the starting position is the position where the measured point coincides with the origin. The platform moves away from the origin step by step according to the preset step size. The preset step size is greater than or equal to 0.3 meters and less than or equal to 0.7 meters.

5. The method according to claim 1, characterized in that, The static measurement also includes: When the bracket fixing the first magnetometer probe causes the measured point to not coincide with the origin, in the last measurement direction before the bracket needs to be moved, after the magnetic field stabilizes, record the first magnetic induction intensity value measured by the first magnetometer probe and the magnetic diurnal variation value measured by the second magnetometer probe. Move the bracket to the designated position, and after the magnetic field stabilizes, record the first magnetic induction intensity value measured by the first magnetometer probe and the magnetic diurnal variation value measured by the second magnetometer probe again. Based on the values ​​recorded before and after the movement, the static measurement data in each measurement direction after the support was moved were normalized.

6. The method according to claim 1, characterized in that, The second magnetometer probe is placed at a location far from the measurement site; Before starting static measurement, determine whether the trend of change of the magnetic diurnal variation curve and the magnetic field curve of the first magnetometer probe at the origin is stable and consistent. If so, start measurement.

7. The method according to claim 1, characterized in that, In the dynamic measurement, the center position of the flight platform is on the same vertical line as the origin at the take-off and landing point for each take-off and landing; with the initial position of the measured point as the zero point, a distance mark is set outward along the measurement direction at preset steps; The flight platform hovers at a preset height directly above the origin in an air-hovering state. When there are multiple test points, a magnetometer probe with the same number of test points is set up, and each magnetometer probe corresponds to each test point to observe the magnetic induction intensity change characteristics of all test points at the same time.

8. The method according to claim 1, characterized in that, The step of determining the first minimum distance from the measured point to the probe when the magnetic induction intensity direction difference of the measured point in a static state is less than a preset direction difference threshold based on static measurement data includes: Subtract the corresponding magnetic diurnal variation value from the first magnetic flux density value measured by the first magnetometer probe at each distance to obtain the magnetic flux density difference value at each measurement direction and distance. For the same distance, the difference between the maximum and minimum values ​​of the magnetic induction intensity differences in each measurement direction is taken as the direction difference of the measured point at that distance; When the directional difference is less than a preset directional difference threshold, the distance corresponding to the directional difference is determined as the first minimum distance.

9. The method according to claim 1, characterized in that, The second minimum distance from the measured point to the probe when the change in magnetic induction intensity at the measured point during the takeoff and landing of the flight platform tends to a fixed value, determined based on dynamic measurement data, includes: The average value of the second magnetic induction intensity measured by the magnetometer probe before takeoff and after landing is subtracted from the value of the second magnetic induction intensity measured by the magnetometer probe during hovering to obtain the change in magnetic induction intensity in each measurement direction and at each distance. When the change in magnetic induction intensity in all measurement directions at a given distance tends to a fixed value, that distance is determined as the second minimum distance.

10. The method according to claim 1, characterized in that, Determining the installation position and length of the probe rod based on the first minimum distance and the second minimum distance includes: The larger of the first minimum distance and the second minimum distance is determined as the minimum length of the probe. When the flight platform is equipped with multiple aeromagnetic probes, multiple test points are determined, the same number as the number of aeromagnetic probes. Static measurement and dynamic measurement are performed on each test point to determine the probe length corresponding to each test point.

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