A magnetic source ground-to-air transient electromagnetic three-component measurement system and measurement method

Abstract

The present invention belongs to the field of magnetic source ground-to-air transient electromagnetic measurement technology, and in particular, relates to a magnetic source ground-to-air transient electromagnetic three-component measurement system and a measurement method. The magnetic source ground-to-air transient electromagnetic three-component measurement system includes a magnetic source transmitting system, a three-component aerial receiving system, and a synchronization system. The magnetic source transmitting system is used to transmit a primary magnetic field on the ground to stimulate an underground target body to generate a secondary induced magnetic field. The three-component aerial receiving system is used to measure the three-component response of the secondary induced magnetic field generated by the magnetic source transmitting system to stimulate the underground target body. The synchronization system is used to perform timing and positioning on the three-component aerial receiving system. The present invention realizes rapid acquisition of three-component transient electromagnetic data, and uses a director to correct the original data to obtain normalized three-component data.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic source ground-to-air transient electromagnetic measurement, and in particular relates to a magnetic source ground-to-air transient electromagnetic three-component measurement system and a measurement method. Background Art

[0002] In mountainous areas with complex terrain, gullies and dense vegetation, conventional ground geophysical methods are limited by complex terrain conditions, construction difficulties and long data collection cycles, and cannot meet the current actual needs of rapid and reliable detection of underground structures. Therefore, it is very necessary to carry out research on ground-to-air transient electromagnetic detection methods and technologies. The ground-to-air transient electromagnetic method is a semi-aeronautical transient electromagnetic device that transmits on the ground and receives in the air. It is a rapid exploration method developed in recent years. It has the characteristics of large exploration depth and high data quality. It is currently mainly used in coal fields, engineering surveys and other fields. Studies have shown that the ground-to-air transient electromagnetic method has great application potential in the fields of minerals, oil and gas, and geological disasters. However, my country started late in the field of aerogeophysics, and its equipment is backward. Limited by the level of flight platform equipment, my country's ground-to-air transient electromagnetic detection system is still very imperfect.

[0003] The ground-to-air transient electromagnetic detection system based on drones uses a launch system to launch on the ground, and carries the receiver and sensor on a rotorcraft drone to carry out measurements. The hollow coil transient electromagnetic sensor currently used for aerial collection can only measure the vertical component, and the single component has defects in the detection of complex targets, and the boundary of the target is not clearly reflected, which cannot meet actual needs.

[0004] Conventional ground-to-air transient electromagnetic method is to transmit on the ground through a grounded electrical source, and the receiving system in the air only receives the transient response of the vertical component. In areas with poor grounding conditions such as deserts and Gobi, the grounding resistance problem of the electrical transmitting grounding source is difficult to deal with, and the transmitting current is difficult to supply large current. In addition, there are surface saline-alkali crusts in some areas, and the power supply current will run along the layer, which cannot achieve the expected purpose. On the other hand, the single component transient response in the receiving system does not clearly reflect the boundary of the target geological body. During actual field measurements, the three-component coil will rotate in the air, and the vertical (Z) component probe will not be affected by the rotation of the probe itself on data acquisition. However, when measuring the horizontal (X, Y) components, the rotation of the coil itself in the air will have a huge impact on the measurement data. Therefore, the horizontal component (X, Y) must be corrected for angle.

[0005] The present invention proposes a magnetic source ground-to-air transient electromagnetic three-component measurement system and measurement method, which utilizes an ungrounded magnetic loop source to be transmitted on the ground through a loop transmitting frame, and uses a rotor-mounted unmanned aerial vehicle equipped with a receiver and a three-component sensor based on a director to measure in the air the transient electromagnetic three-component response stimulated by the ground transmitting system, so as to obtain more abundant information on the target geological body. Summary of the invention

[0006] The present invention provides a magnetic source ground-to-air transient electromagnetic three-component measurement system and a measurement method, aiming to realize rapid acquisition of three-component transient electromagnetic data, and to correct the original data using a director to obtain normalized three-component data.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A magnetic source ground-to-air transient electromagnetic three-component measurement system, comprising a magnetic source transmitting system, a three-component air receiving system and a synchronization system;

[0009] The magnetic source transmitting system includes a transmitter, a rectifier, a generator and a transmitting frame. One end of the rectifier is connected to the generator, and the other end of the rectifier is connected to the transmitter. The transmitter is connected to two connectors of the transmitting frame through a terminal. The magnetic source transmitting system is used to transmit a primary magnetic field on the ground to stimulate an underground target body to generate a secondary induced magnetic field.

[0010] The three-component aerial receiving system includes a UAV and a carrying platform arranged below the UAV, a receiver is arranged on the carrying platform, a three-component sensor is connected to the bottom of the carrying platform through a suspension rope, and the receiver is connected to the three-component sensor through an induction coil connecting line; the three-component aerial receiving system is used to measure the three-component response of the secondary induced magnetic field generated by the magnetic source transmitting system exciting the underground target body;

[0011] The synchronization system is used for timing and positioning of the three-component air receiving system.

[0012] Furthermore, the synchronization system includes a GPS synchronization device arranged on the UAV, and the GPS synchronization device is respectively connected to the transmitter and the receiver.

[0013] Furthermore, the three-component sensor includes two coil horizontal brackets corresponding to the X-axis and Y-axis directions, a coil vertical bracket corresponding to the Z-axis direction, a hollow coil corresponding to the three components of Z, X, and Y, and a director corresponding to the horizontal component. The coil horizontal bracket is connected to the coil vertical bracket and is perpendicular to each other. The hollow coil is connected to the coil horizontal bracket and the coil vertical bracket to form a spherical structure. The hollow coil is connected to the receiver through induction coil connecting lines, and the director is arranged at the intersection of the coil horizontal bracket and the coil vertical bracket.

[0014] Furthermore, the initial direction of the director is consistent with the normal axis of the X-component coil and is perpendicular to the normal axis of the Y-component coil.

[0015] Furthermore, the outer side of the induction coil connecting wire is wrapped with a shielded cable.

[0016] A method for measuring three-component ground-to-air transient electromagnetic of a magnetic source comprises the following steps:

[0017] S1. Arrange a loop transmission source on the ground; use a magnetic source transmission system to transmit a primary field underground to generate a secondary field;

[0018] S2. Prepare a three-component aerial receiving system, measure the three-component response of the secondary induced magnetic field generated by the magnetic source transmitting system to stimulate the underground target body through a three-component sensor, and orient the measured data of the X and Y horizontal components through a direction finder to provide a basis for subsequent data correction;

[0019] S3, the three-component aerial receiving system starts working after the drone takes off and flies to the designated endpoint of the survey line, and simultaneously measures the three-component response of the secondary field and the data of the director. The measurement only records the secondary field signal after shutdown. The measurement is continuous and synchronized through the synchronization system;

[0020] S4. After measuring each measuring point in turn, the three-component data of the measured secondary field are corrected according to the directional data measured by the orientator to obtain the corrected three-component data.

[0021] Furthermore, in step S3, the flight speed of the UAV does not exceed 5 m / s and the flight altitude is below 50 meters.

[0022] Furthermore, in step S3, the measurement is performed with the coil normal direction perpendicular to the ground set as the Z component, the coil normal direction along the flight direction set as the X component, and the Y component is determined according to the right-hand spiral criterion.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention adopts a drone equipped with a receiver and a three-component sensor, the three-component sensor includes two coil horizontal brackets corresponding to the X-axis and Y-axis directions, a coil vertical bracket corresponding to the Z-axis direction, hollow coils corresponding to the three components of Z, X, and Y, and an orienter corresponding to the horizontal component, the coil horizontal bracket is connected to the coil vertical bracket and is perpendicular to each other, the hollow coil is connected to the coil horizontal bracket and the coil vertical bracket to form a spherical structure, the hollow coil is connected to the receiver through an induction coil connecting line, and the orienter is arranged at the intersection of the coil horizontal bracket and the coil vertical bracket. The present invention can measure the measuring point by fast flight, realize the rapid collection of three-component transient electromagnetic data, and use the orienter on the three-component sensor to correct the original data to obtain normalized three-component data, which is more sensitive and reliable to the center and boundary of the abnormal body compared to the current single-component coil measured data, and the corrected three-component data is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the overall structure diagram of the magnetic source ground-to-air transient electromagnetic three-component measurement system;

[0026] Figure 2This is a schematic diagram of the three-component sensor structure of the magnetic source ground-to-space transient electromagnetic three-component measurement system.

[0027] Among them: 1-UAV; 2-carrying platform; 3-receiver; 4-sling; 5-GPS synchronization device; 6-induction coil connecting line; 7-shielded cable; 8-coil horizontal bracket; 9-coil vertical bracket; 10-hollow coil; 11-orientator. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1 , Figure 2 As shown, a magnetic source ground-to-air transient electromagnetic three-component measurement system includes a magnetic source transmitting system, a three-component airborne receiving system and a synchronization system.

[0030] The magnetic source transmission system is used to transmit a primary magnetic field on the ground to stimulate the underground target to generate a secondary induced magnetic field. The magnetic source transmission system includes a transmitter, a rectifier, a generator, and a transmission frame. One end of the rectifier is connected to the generator and the other end is connected to the transmitter. The two connectors of the transmitter frame are connected through special terminals on the transmitter. The generator is used to generate 220V AC voltage, which is converted into DC voltage by the rectifier. The transmitter converts the converted DC voltage into a bipolar square wave with a duty cycle of 50% and transmits it through the transmission frame, generating a primary field in the underground medium and then stimulating the generation of a secondary field.

[0031] The three-component aerial receiving system is used to measure the three-component response of the secondary induced magnetic field generated by the underground target. The three-component aerial receiving system includes an unmanned aerial vehicle 1 and a carrying platform 2 arranged below the unmanned aerial vehicle, wherein a receiver 3 is arranged on the carrying platform 2, and the three-component sensor is connected to the bottom of the carrying platform 2 through a suspension rope 4; the receiver 3 is connected to the GPS synchronization device 5 through a GPS connection line, and the receiver 3 is connected to the three-component sensor through an induction coil connection line 6, and the outer side of the induction coil connection line 6 is wrapped with a shielded cable 7. The carrying platform 2 is used to carry the receiver 3 and suspend the three-component sensor to realize rapid flight measurement; the main function of the receiver 3 is to receive the secondary field signal of the three-component sensor.

[0032] The three-component sensor includes two coil horizontal brackets 8 corresponding to the X-axis and the Y-axis, a coil vertical bracket 9 corresponding to the Z-axis, hollow coils 10 of the three components of Z, X, and Y, and a director 11 of the horizontal component. The coil horizontal bracket 8 is connected to the coil vertical bracket 9 and is perpendicular to each other. The hollow coil 10 forms a spherical structure by connecting the coil horizontal bracket 8 and the coil vertical bracket 9. The hollow coil 10 is connected to the receiver 3 through the induction coil connecting line 6. The director 11 is set at the intersection of the coil horizontal bracket 8 and the coil vertical bracket 9. The three-component sensor is used to measure the secondary field signal of three components. The directional function of the director 11 is used to correct the signal of the horizontal component, wherein the initial direction of the director 11 is consistent with the normal axis of the X-component coil and perpendicular to the normal axis of the Y-component coil.

[0033] The synchronization system includes a GPS synchronization device 5 arranged on the UAV, and the GPS synchronization device 5 is connected to the transmitter and the receiver 3 respectively, and its main functions are timing and positioning.

[0034] A method for measuring three-component ground-to-air transient electromagnetic of a magnetic source comprises the following steps:

[0035] S1. Arrange a loop transmission source on the ground; use a magnetic source transmission system to transmit a primary field underground to generate a secondary field;

[0036] S2. Prepare a three-component aerial receiving system, measure the three-component response of the secondary induced magnetic field generated by the magnetic source transmitting system to stimulate the underground target body through a three-component sensor, and orient the measured data of the X and Y horizontal components through a direction finder to provide a basis for subsequent data correction;

[0037] S3, the three-component aerial receiving system starts working after the drone takes off and flies to the designated endpoint of the survey line, and simultaneously measures the three-component response of the secondary field and the data of the director. The measurement only records the secondary field signal after shutdown. The measurement is continuous and synchronized through the synchronization system;

[0038] S4. After measuring each measuring point in turn, the three-component data of the measured secondary field are corrected according to the directional data measured by the orientator to obtain the corrected three-component data.

[0039] The present invention is further described in detail below by taking the use of a magnetic source ground-to-air transient electromagnetic three-component measurement system to detect irregular block metal ore bodies buried hundreds of meters underground as an example:

[0040] S1. Arrange the loop transmission source on the ground, the transmission frame side length is 200 meters to 800 meters, the transmission current is greater than 10A, and the transmission base frequency is less than 25Hz;

[0041] S2, using the magnetic source launch system to launch a primary field underground according to the set launch parameters, to stimulate the underground metal ore body to generate a secondary field;

[0042] S3. Assemble a three-component aerial receiving system. Generally, the Z component is set as the normal direction of the coil perpendicular to the ground, and the X component is set as the normal direction of the coil along the flight direction. The Y wind volume is determined according to the right-hand spiral criterion. The flight speed of the UAV does not exceed 5m / s, and the flight altitude is below 50 meters to better receive high-quality signals.

[0043] S4. The measurement only records the secondary field signal after shutdown, and the measurement superposition times are set not to exceed 128 times. The measurement mode is continuous measurement, GPS synchronization, the initial point number is set to 0001, and the point number is automatically increased by 1.

[0044] S5. Use a three-component aerial receiving system to simultaneously measure the secondary field responses of the three components and the directional data of the director.

[0045] S6. The three-component data after multiple stacking and the director data are taken as the data measurement result of a point and saved in point number 0001.

[0046] S7. Continue the flight measurement and save the data of subsequent measurement points in point numbers 0002, 0003, etc.

[0047] S8. After the flight measurement is completed, the three-component data are sent back to the computer and processed in the corresponding data processing software. The data are corrected point by point according to the orientator data to obtain the corrected three-component data.

[0048] S9. Invert the corrected three-component data to obtain more accurate and reliable interpretation results.

[0049] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that people in the relevant technical field can well understand and use the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A magnetic source ground-to-air transient electromagnetic three-component measurement system, characterized by: It includes a magnetic source transmitting system, a three-component aerial receiving system and a synchronization system; The magnetic source transmitting system comprises a transmitter, a rectifier, a generator and a transmitting frame, one end of the rectifier is connected to the generator, the other end of the rectifier is connected to the transmitter, and the transmitter is connected to two connectors of the transmitting frame through a terminal; the magnetic source transmitting system is used to transmit a primary magnetic field on the ground to stimulate an underground target body to generate a secondary induced magnetic field; The three-component aerial receiving system comprises an unmanned aerial vehicle (1) and a carrying platform (2) arranged below the unmanned aerial vehicle (1); a receiver (3) is arranged on the carrying platform (2); a three-component sensor is connected to the bottom of the carrying platform (2) via a suspension rope (4); and the receiver (3) is connected to the three-component sensor via an induction coil connecting line (6); the three-component aerial receiving system is used to measure the three-component response of the secondary induced magnetic field generated by the magnetic source transmitting system exciting the underground target body; The synchronization system is used to provide timing and positioning for the three-component aerial receiving system; The three-component sensor comprises two coil horizontal brackets (8) corresponding to the X-axis and Y-axis directions, a coil vertical bracket (9) corresponding to the Z-axis direction, hollow coils (10) corresponding to the three components of Z, X and Y, and an orienter (11) corresponding to the horizontal component, wherein the coil horizontal bracket (8) and the coil vertical bracket (9) are connected and are perpendicular to each other, the hollow coils (10) are connected to the coil horizontal bracket (8) and the coil vertical bracket (9) to form a spherical structure, the hollow coils (10) are connected to the receiver (3) via induction coil connecting lines (6), and the orienter (11) is arranged at the intersection of the coil horizontal bracket (8) and the coil vertical bracket (9); The initial direction of the director is consistent with the normal axis of the X-component coil and is perpendicular to the normal axis of the Y-component coil.

2. The magnetic source ground-to-air transient electromagnetic three-component measurement system according to claim 1 is characterized in that: The synchronization system comprises a GPS synchronization device (5) arranged on the drone (1), the GPS synchronization device (5) being connected to a transmitter and a receiver (3) respectively, and the synchronization system is used for timing and positioning.

3. The magnetic source ground-to-air transient electromagnetic three-component measurement system according to claim 1 is characterized in that: The outer side of the induction coil connecting line (6) is wrapped with a shielded cable (7).

4. A magnetic source ground-to-air transient electromagnetic three-component measurement method, implemented based on the magnetic source ground-to-air transient electromagnetic three-component measurement system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Arrange a loop transmission source on the ground; use a magnetic source transmission system to transmit a primary field underground to generate a secondary field; S2. Prepare a three-component aerial receiving system, measure the three-component response of the secondary induced magnetic field generated by the magnetic source transmitting system to stimulate the underground target body through a three-component sensor, and orient the measured data of the X and Y horizontal components through a direction finder to provide a basis for subsequent data correction; S3, the three-component aerial receiving system starts working after the drone takes off and flies to the designated endpoint of the survey line, and simultaneously measures the three-component response of the secondary field and the data of the director. The measurement only records the secondary field signal after shutdown. The measurement is continuous and synchronized through the synchronization system; S4. After measuring each measuring point in turn, the three-component data of the measured secondary field are corrected according to the directional data measured by the orientator to obtain the corrected three-component data.

5. The magnetic source ground-to-air transient electromagnetic three-component measurement method according to claim 4 is characterized in that: In step S3, the flying speed of the UAV does not exceed 5 m / s and the flying altitude is below 50 meters.

6. The magnetic source ground-to-air transient electromagnetic three-component measurement method according to claim 5 is characterized in that: In step S3, the measurement is performed by setting the normal direction of the coil perpendicular to the ground as the Z component, the normal direction of the coil along the flight direction as the X component, and then determining the Y component according to the right-hand spiral criterion.

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