Unmanned aerial vehicle airborne electromagnetic detection system based on gradient difference coil and design method

Abstract

The present application belongs to the technical field of unmanned aerial vehicle airborne electromagnetic detection, and relates to an unmanned aerial vehicle airborne electromagnetic detection system based on gradient differential coils and a design method thereof. The present application makes the mutual inductance coefficient zero by accurately designing the relative position of the transmitting and receiving coils, thereby eliminating the direct coupling of the primary field generated by the off of the transmitting current in the receiving coil from the source, and reducing the shallow detection blind area. The lateral gradient differential technology is adopted, which has a natural inhibitory effect on common mode interference such as environmental noise, and the signal-to-noise ratio is further improved by double-differential signal superposition. The designed gradient differential coil can clearly distinguish the left and right boundaries of the conductive ring model, while the traditional single coil can only identify one boundary, thereby improving the lateral resolution capability for small-scale or adjacent geoelectric target bodies. The coil structure layout is regular and relatively small in size, and is very suitable for unmanned aerial vehicle platforms with limited load space and weight, thereby providing a hardware foundation for realizing high-precision airborne electromagnetic detection.

Description

Technical Field

[0001] This invention belongs to the field of UAV aerial electromagnetic detection technology, specifically relating to a UAV aerial electromagnetic detection system and design method based on gradient differential coils. Background Technology

[0002] Airborne electromagnetic detection (AEFD) technology, as a highly efficient geophysical exploration method, has been widely applied in many fields such as mineral resource exploration, geological structure analysis, and underground pipeline detection. Based on the principle of electromagnetic induction, AEFD works by transmitting a primary electromagnetic field into the underground through a transmitting coil, which excites induced eddy currents (i.e., a secondary field) in the underground medium. The secondary field signal is then detected by a receiving coil, thereby obtaining information about the underground electrical structure.

[0003] Traditional airborne transient electromagnetic systems typically use a single coil as the receiving unit, which has the following obvious technical limitations: on the one hand, in the early time channel, the primary and secondary field signals are prone to aliasing, resulting in a large shallow detection blind zone; on the other hand, due to volume effects and external environmental noise interference, the system has low lateral resolution, making it difficult to accurately identify small or nearby ground electrical targets.

[0004] With the widespread application of unmanned aerial vehicle (UAV) platforms, the cost and safety of airborne electromagnetic systems have been significantly improved. However, detection accuracy and anti-interference capabilities remain key issues restricting their further development. Although a few researchers have attempted to improve the signal-to-noise ratio through multi-coil arrangements or differential methods, systematic optimization is still lacking in areas such as transceiver coil coupling design, primary field suppression capability, and lateral resolution improvement.

[0005] Therefore, there is an urgent need to develop a new type of transceiver coil structure that can effectively suppress primary field interference in strong noise environments and improve the ability to distinguish small-sized ground electrical targets, so as to meet the high-precision airborne electromagnetic detection requirements under complex terrain conditions. Summary of the Invention

[0006] The purpose of this invention is to provide an unmanned aerial vehicle (UAV) airborne electromagnetic detection system and design method based on gradient differential coils, so as to solve the problems of large shallow blind zone, severe primary field interference, weak environmental noise suppression capability and low lateral resolution in the existing single-receiving coil transient electromagnetic system.

[0007] This invention is achieved through the following technical solution:

[0008] A UAV airborne electromagnetic detection system based on gradient differential coils includes a transmitting coil. and No. 1 receiving coil No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 Composed of drone aviation electromagnetic transceiver coils;

[0009] Among them, the transmitting coil lie in On a plane, its axis is inter... Axis coincidence; No. 1 receiving coil -4 receiving coil They have the same structure and number of turns, and are arranged in the transmitting coils respectively. Eccentric position, horizontal offset distance With transmitting coil Parallel and about the transmitting coil Centrally symmetric;

[0010] No. 1 receiving coil With receiving coil No. 2 It is a set of differential coils, receiving coil No. 3. With receiving coil No. 4 For another set of differential coils, each receiving coil Center and transmitting coil The vertical distance between the centers is transmitting coil The side length is No. 1 receiving coil -4 receiving coil The radii are all ;

[0011] Also includes conductive rings The conductive ring Settings On the axis, located at the transmitting coil Directly below.

[0012] Furthermore, the transmitting coil side length =1.2m, No. 1 receiving coil -4 receiving coil radius =0.15m.

[0013] Furthermore, each receiving coil Center and transmitting coil Vertical distance between centers The value was selected as 0.06m.

[0014] Furthermore, horizontal offset distance =0.619.

[0015] Furthermore, conductive ring With transmitting coil The vertical distance between the planes is 1m, and the conductive ring is... The radius is 0.2m.

[0016] A design method for an unmanned aerial vehicle (UAV) airborne electromagnetic detection system based on gradient differential coils includes the following steps:

[0017] A. Arrangement and setup of UAV electromagnetic transceiver coils:

[0018] transmit coil Set in On a plane, its axis is inter... Shaft alignment; align receiving coil 1 No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 Arranged separately in the transmitting coil Eccentric position, horizontal offset distance With transmitting coil Parallel and about the transmitting coil Centrally symmetrical; No. 1 receiving coil With receiving coil No. 2 It is a set of differential coils, receiving coil No. 3. With receiving coil No. 4 For another set of differential coils, each receiving coil Center and transmitting coil The vertical distance between the centers is transmitting coil The side length is No. 1 receiving coil -4 receiving coil The radii are all ;

[0019] B. Mutual inductance analysis between the transmitting and receiving coils:

[0020] B1. Mutual inductance voltage between the transmitting and receiving coils:

[0021] When the transmitting coil When the current in the circuit is momentarily cut off, the magnetic field it generates will pass through the receiving coil, specifically receiving coil number 1. -4 receiving coil The magnetic flux in the coil changes with the current, thus affecting the No. 1 receiving coil. -4 receiving coil A voltage is induced in the transceiver coil; this voltage is called the mutual inductance voltage. The mutual inductance voltage between the transceiver coils can be expressed as:

[0022] ;

[0023] In the formula, It is receiving coil No. 1. and No. 2 receiving coil The induced voltage on it, It is a transmitting coil With receiving coil No. 1 No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 mutual inductance coefficient, It is the emission current;

[0024] B2. When the mutual inductance between the transmitting and receiving coils is zero, i.e. At that time, the mutual inductance voltage between the transmitting and receiving coils is zero. This eliminates interference from the primary field in transient electromagnetic fields;

[0025] B3, Receiving coil With transmitting coil Mutual inductance coefficient between them:

[0026] According to Neumann's formula, the receiving coil With transmitting coil The mutual inductance coefficient between them can be expressed as:

[0027] ;

[0028] In the formula, each receiving coil Center and transmitting coil The vertical distance between the centers is transmitting coil The side length is No. 1 receiving coil -4 receiving coil The radii are all , H / m is the permeability of free space. and These are the number of turns in the transmitting coil and the receiving coil, respectively, assuming the coil structure is fixed. Only with horizontal offset and each receiving coil Center and transmitting coil Vertical distance between centers related, For the angular integral variable in the plane of the receiving coil, Let be the linear integral variable on the side of the transmitting coil;

[0029] C. Signal Processing:

[0030] First, test the receiving coil No. 1 in the same differential coil. With receiving coil No. 2 The induced voltage signal is differentially processed to eliminate common-mode noise and primary field interference; then the two differential coils are superimposed on the processed differential signal to amplify the effective secondary field signal, obtain pipeline exploration results without blind zones, and eliminate environmental noise interference.

[0031] D. Setting parameters for UAV aerial electromagnetic transceiver coils:

[0032] transmitting coil The side length a = 1.2m, and the radius of the receiving coil... =0.15m, each receiving coil Center and transmitting coil Vertical distance between centers The horizontal offset was selected as 0.06m. =0.619, there is no mutual inductance between the receiving coils;

[0033] E. Establish the conductive loop model:

[0034] The difference between the lateral resolution of the designed coil and that of a single receiving coil is analyzed from a mathematical model perspective. A conductive loop model is established, and the conductive loop is placed in... On the axis, located at the transmitting coil Directly below; along the transmitting coil of Seven points, spaced from point 1 to point 7, are set along the axial direction, each corresponding to a conductive ring. The seven relative positions of the coil, the conductive ring and the transmitting coil The vertical distance to the plane is 1m;

[0035] F. Perform tests on single receiving coil and gradient weakly coupled coil respectively.

[0036] Further, in step A, receiving coil No. 1 -4 receiving coil The structure and number of turns are the same.

[0037] Further, in step E, the conductive ring The radius is 0.2m.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] 1. This invention achieves zero mutual inductance by precisely designing the relative positions of the transmitting and receiving coils, thereby eliminating the direct coupling of the primary field generated by the transmission current turn-off in the receiving coil from the source, solving the early signal aliasing problem, and reducing the shallow detection blind zone.

[0040] 2. The use of transverse gradient differential technology has a natural suppression effect on common-mode interference such as environmental noise, and the signal-to-noise ratio is further improved by superimposing the signals of the dual differential pairs.

[0041] 3. The gradient differential coil designed in this invention can clearly distinguish the left and right boundaries of the conductive ring model, while the traditional single coil can only identify one boundary, which significantly improves the lateral resolution capability for small-scale or nearby geoelectric targets.

[0042] 4. The coil has a regular structure and a relatively small size, making it very suitable for UAV platforms with limited load space and weight, providing a hardware foundation for achieving high-precision airborne electromagnetic detection. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the coil structure and its relative positions;

[0045] Figure 2 This is a schematic diagram showing the relationship between the mutual inductance coefficients of the transmitting and receiving coils and the offset distance.

[0046] Figure 3 This is a diagram of a numerical simulation model of a conductive ring, using only... Voltage characteristic curve during reception;

[0047] Figure 4 For only use Three-dimensional plot of voltage characteristics during reception;

[0048] Figure 5 For only use Voltage characteristic curve during reception;

[0049] Figure 6 For only use Three-dimensional plot of voltage characteristics during reception;

[0050] Figure 7 For only use Voltage characteristic curve during reception;

[0051] Figure 8 To utilize simultaneously and Three-dimensional plot of voltage characteristics during reception;

[0052] Figure 9 To utilize simultaneously and Voltage characteristic curve during reception.

[0053] In the picture, : No. 1 receiving coil; Receiver coil #2; Receiver coil #3; Receiver coil #4; : Transmitting coil. Detailed Implementation

[0054] The present invention will be further described below with reference to embodiments:

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0056] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0057] This invention relates to an unmanned aerial electromagnetic detection system based on gradient differential coils, comprising a transmitting coil. and No. 1 receiving coil No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 Composed of drone aviation electromagnetic transceiver coils;

[0058] Among them, the transmitting coil lie in On a plane, its axis is inter... Axis coincidence; No. 1 receiving coil -4 receiving coil They have the same structure and number of turns, and are arranged in the transmitting coils respectively. Eccentric position, horizontal offset distance With transmitting coil Parallel and about the transmitting coil Centrally symmetrical; No. 1 receiving coil With receiving coil No. 2 It is a set of differential coils, receiving coil No. 3. With receiving coil No. 4 For another set of differential coils, each receiving coil (including receiving coil No. 1) No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 The center and transmitting coil The vertical distance between the centers is transmitting coil The side length is No. 1 receiving coil -4 receiving coil The radii are all It also includes conductive rings. The conductive ring Settings On the axis, located at the transmitting coil Directly below.

[0059] Specifically, the transmitting coil side length =1.2m, receiving coil radius =0.15m. Each receiving coil Center and transmitting coil Vertical distance between centers The selected value is 0.06m. The horizontal offset distance s = 0.619. Conductive ring. With transmitting coil The vertical distance between the planes is 1m, and the conductive ring is... The radius is 0.2m.

[0060] The present invention discloses a design method for an unmanned aerial vehicle (UAV) airborne electromagnetic detection system based on gradient differential coils, comprising the following steps:

[0061] A. Arrangement and setup of UAV electromagnetic transceiver coils:

[0062] transmit coil Set in On a plane, its axis is inter... Shaft alignment; align receiving coil 1 No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 Arranged separately in the transmitting coil Eccentric position, horizontal offset distance With transmitting coil Parallel and about the transmitting coil Centrally symmetrical; No. 1 receiving coil With receiving coil No. 2 It is a set of differential coils, receiving coil No. 3. With receiving coil No. 4 This is another set of differential coils. Receiver coil number 1. -4 receiving coil The structure and number of turns are the same.

[0063] B. Mutual inductance analysis between the transmitting and receiving coils:

[0064] B1. Mutual inductance voltage between the transmitting and receiving coils:

[0065] When the transmitting coil When the current in the circuit is momentarily cut off, the magnetic field it generates will pass through the receiving coil, specifically receiving coil number 1. -4 receiving coil The magnetic flux in the coil changes with the current, thus affecting the No. 1 receiving coil. -4 receiving coil A voltage is induced in the transceiver coil; this voltage is called the mutual inductance voltage. The mutual inductance voltage between the transceiver coils can be expressed as:

[0066] ;

[0067] In the formula, It is receiving coil No. 1. and No. 2 receiving coil The induced voltage on it, It is a transmitting coil With receiving coil No. 1 No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 mutual inductance coefficient, It is the emission current;

[0068] B2. When the mutual inductance between the transmitting and receiving coils is zero, i.e. At that time, the mutual inductance voltage between the transmitting and receiving coils is zero. This eliminates interference from the primary field in transient electromagnetic fields;

[0069] B3, Receiving coil With transmitting coil Mutual inductance coefficient between them:

[0070] According to Neumann's formula, the receiving coil With transmitting coil The mutual inductance coefficient between them can be expressed as:

[0071] ;

[0072] In the formula, each receiving coil The vertical distance between the center of the transmitter coil T and the center of the transmitting coil T is transmitting coil The side length is No. 1 receiving coil -4 receiving coil The radii are all , H / m is the permeability of free space. and These are the number of turns in the transmitting coil and the receiving coil, respectively, assuming the coil structure is fixed. Only with horizontal offset and each receiving coil Center and transmitting coil Vertical distance between centers related, For the angular integral variable in the plane of the receiving coil, Let be the linear integral variable on the side of the transmitting coil.

[0073] C. Signal Processing:

[0074] First, test the receiving coil No. 1 in the same differential coil. With receiving coil No. 2 The induced voltage signal is differentially processed to eliminate common-mode noise and primary field interference; then the two differential coils are superimposed on the processed differential signal to amplify the effective secondary field signal, obtain pipeline exploration results without blind zones, and eliminate environmental noise interference.

[0075] D. Setting parameters for UAV aerial electromagnetic transceiver coils:

[0076] transmitting coil side length =1.2m, receiving coil radius =0.15m, each receiving coil Center and transmitting coil Vertical distance between centers The horizontal offset was selected as 0.06m. =0.619, there is no mutual inductance between the receiving coils.

[0077] E. Establish the conductive loop model:

[0078] Analyze the difference between the lateral resolution of the designed coil and that of a single receiving coil, establish a conductive loop model, and place the conductive loop in... On the axis, located at the transmitting coil Directly below; along the transmitting coil of Seven points, spaced from point 1 to point 7, are set along the axial direction, each corresponding to a conductive ring. The conductive rings are in seven relative positions to the coil. With transmitting coil The vertical distance between the planes is 1m; conductive ring The radius is 0.2m.

[0079] F. Perform tests on single receiving coil and gradient weakly coupled coil respectively.

[0080] Example 1:

[0081] A UAV airborne electromagnetic detection system based on gradient differential coils includes UAV airborne electromagnetic transceiver coils, the structure of which is as follows: Figure 1 As shown. The transmitting coil... lie in On a plane, its axis is inter... Shaft coincidence, receiving coil In this embodiment, it is receiving coil number 1. No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 That is, receiving coil No. 1 -4 receiving coil They have the same structure and number of turns, and are arranged in the transmitting coils respectively. Eccentric position, horizontal offset distance With transmitting coil Parallel and about the transmitting coil Centrally symmetrical. Among them, receiving coil number 1... With receiving coil No. 2 It is a set of differential coils, receiving coil No. 3. With receiving coil No. 4 For another set of differential coils, each receiving coil Center and transmitting coil The vertical distance between the centers is transmitting coil The side length is No. 1 receiving coil -4 receiving coil The radii are all .

[0082] When the transmitting coil When the current in the circuit is momentarily cut off, the magnetic field it generates will pass through the receiving coil, specifically receiving coil number 1. -4 receiving coil The magnetic flux in the coil changes with the current, thus affecting the No. 1 receiving coil. -4 receiving coil A voltage is induced in the transceiver coil; this voltage is called the mutual inductance voltage. The mutual inductance voltage between the transceiver coils can be expressed as:

[0083] ;

[0084] In the formula, It is receiving coil No. 1. and No. 2 receiving coil The induced voltage on it, It is the transmitting coil T and the receiving coil No. 1. No. 2 receiving coil No. 3 receiving coil and receiving coil No. 4 mutual inductance coefficient, It is the emission current.

[0085] From this formula, we can see that when the mutual inductance between the transmitting and receiving coils is zero, that is... At that time, the mutual inductance voltage between the transmitting and receiving coils is zero. Theoretically, it can eliminate interference from the primary field in transient electromagnetic fields.

[0086] According to Neumann's formula, the receiving coil With transmitting coil The mutual inductance coefficient between them can be expressed as:

[0087] ;

[0088] In the formula, H / m is the permeability of free space. and These are the number of turns in the transmitting coil and the receiving coil, respectively, assuming the coil structure is fixed. Only with horizontal offset and each receiving coil Center and transmitting coil Vertical distance between centers related.

[0089] In terms of signal processing, this invention first processes the first receiving coil in the same differential coil. With receiving coil No. 2 The induced voltage signal is differentially processed to eliminate common-mode noise and primary field interference. Subsequently, the processed differential signals are superimposed by two differential coils to further amplify the effective secondary field signal, obtaining pipeline exploration results without blind zones. This also eliminates environmental noise interference, resulting in more accurate data features and higher resolution.

[0090] The transmitting coil designed in this invention side length =1.2m, receiving coil radius =0.15m, considering practical engineering issues, each receiving coil Center and transmitting coil Vertical distance between centers The value was selected as 0.06m. Horizontal offset distance Relationships, such as Figure 2 As shown, to eliminate the influence of the primary field, the horizontal offset distance... =0.619m. The mutual inductance between the receiving coils has a negligible effect; therefore, it can be considered that there is no mutual inductance between the receiving coils.

[0091] To analyze the difference between the lateral resolution of the designed coil and that of a single take-up coil, a system is established as follows: Figure 3 The conductive ring model shown has seven relative positions between the conductive ring and the coil, from point 1 to point 7. With transmitting coil The vertical distance between the two planes is 1m, and the horizontal relative distance is shown in Table 1. (Conductive ring) The radius is 0.2m. This invention uses a conductive ring to simulate underground anomalies in geophysical electromagnetic detection, and compares the received signals of a traditional single receiving coil and the weak gradient coupling coil proposed in this invention, finding that the weak gradient coupling coil performs better.

[0092] Table 1:

[0093]

[0094] in, It is a conductive ring. For transmitting coil, and These are receiving coils No. 1. No. 2 receiving coil .

[0095] Single receiver coil test:

[0096] Using only a single receiving coil, a traditional airborne electromagnetic detection device is simulated. A conductive ring target is guided horizontally past seven predetermined points, and the induced voltage of the coil at each point is recorded. For example... Figures 4-7 As shown, the induced voltage curve exhibits a broad, gentle single peak. The system can only detect the approximate existence of the target, unable to distinguish its left and right boundaries, exhibiting low lateral resolution of approximately 0.5 meters, and the early signal is susceptible to primary field interference.

[0097] Gradient weakly coupled coil test:

[0098] Using a pair of symmetrically arranged receiving coils and First, perform real-time differential processing on the voltage signals of both devices, then analyze the changes in this differential signal with the target position. For example... Figures 8-9As shown, the differential signal curve exhibits two clear, sharp peaks with opposite polarities, precisely corresponding to the left and right boundaries of the conductive ring target. The lateral resolution is significantly improved to approximately 0.2 meters, and direct coupling of the primary field and common-mode ambient noise are fundamentally suppressed.

[0099] Simulation results show that, compared with traditional single-coil technology, the gradient differential design of this invention achieves high-resolution and high-interference-resistant detection of the boundary of small geoelectric targets by measuring the spatial gradient of the magnetic field.

[0100] It should be noted that those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A design method for an unmanned aerial vehicle (UAV) airborne electromagnetic detection system based on gradient differential coils, characterized in that, Includes the following steps: A. Arrangement and setup of UAV electromagnetic transceiver coils: The transmitting coil ( ) set in On a plane, its axis is inter... Shaft alignment; align receiving coil 1 ( ), No. 2 receiving coil ( ), No. 3 receiving coil ( ) and No. 4 receiving coil ( ) are respectively arranged in the transmitting coil ( ) Eccentric position, horizontal offset distance With the transmitting coil ( Parallel and about the transmitting coil ( ) Centrally symmetrical; No. 1 receiving coil ( ) and No. 2 receiving coil ( ) is a set of differential coils, receiving coil No. 3 ( ) and No. 4 receiving coil ( () is another set of differential coils; B. Mutual inductance analysis between the transmitting and receiving coils: B1. Mutual inductance voltage between the transmitting and receiving coils: When the transmitting coil ( When the current in the receiver coil is switched off instantaneously, the magnetic field it generates will pass through the receiving coil. (Receiver coil #1) -4 receiving coil ( The magnetic flux in the ) changes with the change of current, thus affecting the 1st receiving coil ( -4 receiving coil ( A voltage is induced in the transceiver coil, which is called the mutual inductance voltage. The mutual inductance voltage between the transceiver coil can be expressed as: ； In the formula, It is receiver coil number 1 ( ) and No. 2 receiving coil ( The induced voltage on ) It is a transmitting coil ( ) and No. 1 receiving coil ( ), No. 2 receiving coil ( ), No. 3 receiving coil ( ) and No. 4 receiving coil ( The mutual inductance coefficient, It is the emission current; B2. When the mutual inductance between the transmitting and receiving coils is zero, i.e. At that time, the mutual inductance voltage between the transmitting and receiving coils is zero. This eliminates interference from the primary field in transient electromagnetic fields; B3, Receiving coil With the transmitting coil ( Mutual inductance coefficient between: According to Neumann's formula, the receiving coil With the transmitting coil ( The mutual inductance coefficient between them can be expressed as: ； In the formula, each receiving coil The center and transmitting coil ( The vertical distance between the centers of ) is Transmitting coil ( The side length of ) is No. 1 receiving coil ( -4 receiving coil ( The radius of ) is , H / m is the permeability of free space. and These are the number of turns in the transmitting coil and the receiving coil, respectively, assuming the coil structure is fixed. Only with horizontal offset and each receiving coil The center and transmitting coil ( Vertical distance between the centers of ) related, For the angle integral variable in the plane of the receiving coil, Let be the linear integral variable on the side of the transmitting coil; C. Signal Processing: First, test the receiving coil No. 1 in the same differential coil ( ) and No. 2 receiving coil ( The induced voltage signal is differentially processed to eliminate common-mode noise and primary field interference; The two differential coils are then superimposed on the processed differential signal to amplify the effective secondary field signal, obtain pipeline exploration results without blind spots, and eliminate environmental noise interference. D. Setting parameters for UAV aerial electromagnetic transceiver coils: Transmitting coil ( The side length of ) =1.2m, receiving coil radius =0.15m, each receiving coil The center and transmitting coil ( Vertical distance between the centers of ) The horizontal offset was selected as 0.06m. =0.619, there is no mutual inductance between the receiving coils; E. Establish the conductive loop model: Analyze the difference between the lateral resolution of the designed coil and that of a single receiving coil, establish a conductive loop model, and place the conductive loop in... On the axis, located at the transmitting coil ( Directly below; along the transmitting coil ( )of Seven points, spaced from point 1 to point 7, are set along the axial direction, each corresponding to a conductive ring. The seven relative positions of the coil, the conductive ring and the transmitting coil ( The vertical distance between the plane containing the object is 1m; F. Perform tests on single receiving coil and gradient weakly coupled coil respectively; Among them, the UAV airborne electromagnetic detection system based on gradient differential coils includes a transmitting coil ( ) and No. 1 receiving coil ( ), No. 2 receiving coil ( ), No. 3 receiving coil ( ) and No. 4 receiving coil ( The drone's aviation electromagnetic transceiver coil consists of ) Among them, the transmitting coil ( )lie in On a plane, its axis is inter... Axis coincidence; No. 1 receiving coil ( -4 receiving coil ( The structures and number of turns are the same, and they are arranged in the transmitting coil ( ) Eccentric position, horizontal offset distance With the transmitting coil ( Parallel and about the transmitting coil ( Centrally symmetric; No. 1 receiving coil ( ) and No. 2 receiving coil ( ) is a set of differential coils, receiving coil No. 3 ( ) and No. 4 receiving coil ( (This is) another set of differential coils, each receiving coil The center and transmitting coil ( The vertical distance between the centers of ) is Transmitting coil ( The side length of ) is No. 1 receiving coil ( -4 receiving coil ( The radius of ) is ; Also includes conductive rings The conductive ring Settings On the axis, located at the transmitting coil ( Directly below; The transmitting coil ( The side length of ) =1.2m, No. 1 receiving coil ( -4 receiving coil ( radius =0.15m; each receiving coil The center and transmitting coil ( Vertical distance between the centers of ) Selected as 0.06m; Horizontal offset distance =0.619; Conductive ring With the transmitting coil ( The vertical distance between the plane and the conductive ring is 1m. The radius is 0.2m.

2. The design method of an unmanned aerial vehicle (UAV) airborne electromagnetic detection system based on gradient differential coils according to claim 1, characterized in that: Step A, receiving coil No. 1 ( -4 receiving coil ( The structure and number of turns are the same.

3. The design method of an unmanned aerial vehicle (UAV) airborne electromagnetic detection system based on gradient differential coils according to claim 1, characterized in that: Step E, conductive ring The radius is 0.2m.

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