CN116148933A - Receiver for electromagnetic acquisition system of ground-air unmanned aerial vehicle - Google Patents

Abstract

The invention discloses a receiver for an electromagnetic acquisition system of an unmanned ground plane, wherein a semi-aviation electromagnetic system of a magnetic coupling source or a galvanic coupling source transmitting system is used as an airborne receiving system on the ground; the airborne receiving system collects all time sequence data; the receiver consists of a nose cone, a high-precision inertial navigation sensor, a three-component fluxgate sensor, a first protective sleeve, a circuit board, a power supply assembly, a three-component electromagnetic coil, a second protective sleeve and a tail wing, is subjected to miniaturization design and optimization of an attitude algorithm, and greatly reduces the weight and the size of a traditional working mode.

Description

Receiver for electromagnetic acquisition system of ground-air unmanned aerial vehicle

Technical Field

The invention relates to the technical field of physical exploration, in particular to a receiver for an electromagnetic acquisition system of an unmanned ground plane.

Background

In the prior art, the physical exploration technical field is relatively backward, the ground work is mainly used, the efficiency is low, and even workers cannot enter the construction in places with poor geological conditions.

The aeromagnetic total field measurement technology based on the unmanned aerial vehicle platform has been greatly developed in the last 20 years, a large number of unmanned aerial vehicle aeromagnetic measurement systems are developed in a plurality of units at home and abroad, and unmanned helicopters, fixed wing unmanned aerial vehicles and other machine type carried optical pump magnetometers are adopted for working, so that a certain application effect is achieved. The unmanned aerial vehicle platform has the advantages of strong environmental adaptability, low application cost, high personnel safety and the like, and is widely applied to the fields of geological investigation, disaster monitoring, electric power line inspection and the like.

The ground-air transient electromagnetic method is to arrange an alternating current source on the ground surface, an aircraft carries a receiving system to collect transient electromagnetic signals in low air, and a pulse magnetic field is periodically sent to the periphery by an alternating current transmitting coil or a grounding wire on the ground surface; the geologic body is influenced to generate an induced annular vortex, the changed vortex generates an induced magnetic field, namely a secondary field, and the secondary field induces a receiving coil carried by the aircraft again to generate an electric field and is collected by a collector. Through unmanned aerial vehicle mounted coil flight, can acquire the secondary field distribution in observation region fast to carry out data inversion interpretation to the secondary field, and then can know the existence state and the physical property parameter of geologic body.

The electric source ground-air transient electromagnetic method is to periodically send a primary pulse magnetic field to the underground by using an electrified wire AB as a transmitting source, and an induced vortex excited by an abnormal underground body under the action of the primary field generates an induced magnetic field, which is commonly called a secondary field, a receiving coil and a receiver carried by an aircraft receive the secondary field in a current turn-off period, and finally the received secondary field data is subjected to noise elimination and inversion so as to achieve the aim of researching the underground geologic body.

Disclosure of Invention

In order to solve the technical problem of low precision in the prior art, the invention provides a receiver for an electromagnetic acquisition system of an unmanned ground-air vehicle, which can be applied to a multi-rotor unmanned aerial vehicle platform and a helicopter unmanned aerial vehicle platform, and greatly improves the field work efficiency of an electromagnetic method.

In order to achieve the above purpose, the present invention provides the following specific scheme:

the receiver is used for an electromagnetic acquisition system of an unmanned ground plane, and a semi-aviation electromagnetic system of a magnetic coupling source or a galvanic coupling source transmitting system is used as an airborne receiving system on the ground; the airborne receiving system acquires full time sequence data and acquires frequency domain data besides time domain data; the receiver consists of a nose cone, a high-precision inertial navigation, a three-component fluxgate sensor, a first protective sleeve, a circuit board, a power supply assembly, a three-component electromagnetic coil, a second protective sleeve and a tail wing, wherein the nose cone is sequentially connected with the first protective sleeve, the second protective sleeve and the tail wing from top to bottom to form an outer shell of the receiver, the nose cone is connected with the first protective sleeve, the first protective sleeve is connected with the second protective sleeve, the inside of the receiver is hollow, the high-precision inertial navigation, the three-component fluxgate sensor, the circuit board, the power supply assembly and the three-component electromagnetic coil are arranged from top to bottom, and the second protective sleeve is connected with the tail wing; wherein:

providing three-axis attitude data in the same direction as the three-component fluxgate sensor and the three-component electromagnetic coil to calibrate the attitudes of the three-component fluxgate sensor and the three-component electromagnetic coil;

the three-component fluxgate sensor provides three-component magnetic field data, and performs magnetic field data direction calibration in the electromagnetic data on the three-component electromagnetic coil;

the first protective sleeve is used for reducing impact and vibration to the circuit board and the power supply assembly during landing;

the circuit board and the power supply component are used for supplying power and stabilizing voltage;

the three-component electromagnetic coil is used for collecting three-component electromagnetic signals and respectively carrying out attitude and magnetic field change direction calibration through the high-precision inertial navigation and the three-component fluxgate sensor;

the second protective sleeve is used for balancing and stabilizing the protection function of the tail part of the whole receiver;

and the tail fin is used for stabilizing the azimuth and the counterweight effect.

In the technical scheme, the receiver for the electromagnetic acquisition system of the ground-to-air unmanned aerial vehicle is hung at the lower part of the aircraft through the three-point type hook on the outer shell of the receiver and used for avoiding the interference of the aircraft.

In the technical scheme, the three directions of the high-precision inertial navigation, the fluxgate and the three-component electromagnetic coil are completely consistent, and are fixedly connected by adopting a hard non-metal PVC or nylon structural member.

In the technical scheme, all parts of the receiver are fixedly connected through a metal-free nylon or PVC bracket, and the circuits are connected through cable signal wires.

As a preferable scheme of the technical scheme, the three-component electromagnetic coil has the specific structure that electromagnetic signals in the X\Y\Z direction are acquired by three electromagnetic coils which are relatively perpendicular to each other, and each coil is required to be powered by a circuit board and a power supply assembly and is fixed on a nonmetal fixing plate.

As a preferable scheme of the technical scheme, the outer shell material of the receiver is formed by combining PVC and/or polyester brazing non-metal materials.

The receiver for the electromagnetic acquisition system of the ground-to-air unmanned aerial vehicle is miniaturized and optimized in attitude algorithm, and the weight and the size of the traditional working mode are greatly reduced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive faculty for a person skilled in the art.

FIG. 1 is a schematic diagram of a receiver for an electromagnetic acquisition system of an unmanned aerial vehicle;

fig. 2 is a schematic diagram of a combined structure of a high-precision inertial navigation 2, a three-component fluxgate sensor 3, a circuit board, a power supply assembly 5 and a three-component electromagnetic coil 6 of a receiver for an electromagnetic acquisition system of an unmanned aerial vehicle;

fig. 3 is an enlarged view of a portion of a three-component electromagnetic coil 6 of a receiver for an electromagnetic acquisition system of an unmanned aerial vehicle of the present invention;

fig. 4 is a schematic diagram of a combined structure of a second protective cover 7 and a tail wing 8 of a receiver for an electromagnetic acquisition system of an unmanned aerial vehicle according to the present invention.

Fig. 5 is a schematic diagram of a GPS time synchronization procedure of a transmitting, collecting and receiving system of a receiver of an electromagnetic collecting system of an unmanned aerial vehicle according to the present invention.

Fig. 6 is a schematic flow chart of a data acquisition process of a receiver for an electromagnetic acquisition system of an unmanned aerial vehicle according to the present invention.

Fig. 7 is a schematic flow chart of a data preprocessing step of a receiver for an electromagnetic acquisition system of an unmanned aerial vehicle.

In the figure: 1. a nose cone; 2. high-precision inertial navigation; 3. a three-component fluxgate sensor; 4. a first protective sleeve; 5. a circuit board and a power supply assembly; 6. a three-component electromagnetic coil; 7. the second protective sleeve, 8, the fin.

Detailed Description

In order to make the present application solution better understood by those skilled in the art, the following description will be made in detail and with reference to the accompanying drawings in the embodiments of the present application, it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the present application described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In the present application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate an azimuth or a positional relationship based on that shown in the drawings. These terms are used primarily to better describe the present application and its embodiments and are not intended to limit the indicated device, element or component to a particular orientation or to be constructed and operated in a particular orientation.

Also, some of the terms described above may be used to indicate other meanings in addition to orientation or positional relationships, for example, the term "upper" may also be used to indicate some sort of attachment or connection in some cases. The specific meaning of these terms in this application will be understood by those of ordinary skill in the art as appropriate.

Furthermore, the terms "mounted," "configured," "provided," "connected," "coupled," and "sleeved" are to be construed broadly. For example, it may be a fixed connection, a removable connection, or a unitary construction; may be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements, or components. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

[ example 1 ]

The electromagnetic field is vector, and has three components, and the direct use of the field vector to solve the differential equation of the vector is needed, so that the process is more complicated. If the medium and the field source have symmetry, a proper coordinate system is selected, and proper vector bits are introduced, so that only one component of the vector bits can be generally used, and the electromagnetic field can be conveniently solved at the moment. When the coordinate system is selected, the center of the linear source is selected as the origin of the coordinate system, and the direction of the field source is parallel to a certain coordinate axis. Vector bit introduction is generally based on the criterion that when a magnetic source is present, an electrical vector bit is introduced; when an electrical source is present, a magnetic vector bit is introduced. For example, when solving an electromagnetic field of a vertical magnetic dipole of a surface of a uniform earth or a horizontal lamellar earth, a cylindrical coordinate system is generally selected, an origin of the cylindrical coordinate system is selected at the magnetic dipole, and a z-axis is perpendicular to the surface of the earth and coincides with a direction of the magnetic dipole, so that the distribution of the medium and the field source has symmetry with respect to the z-axis, and when an electric vector bit A is introduced, A has only a z-component, and then a vector differential equation with respect to A is simplified to a scalar differential equation, and the solving becomes mathematically easier.

In the embodiment, the detection area of the appointed suspended electromagnetic method is 1.5Km2, and in order to ensure the requirement of boundary detection precision, the detection area is enlarged in design. The specific conditions of the test line design are as follows: the test line is designed to run from north east to south west, the length of each test line is about 1150m, the line distance of the test lines is 50m, 37 test lines are arranged in total, the total flight detection length is 42550m, and the effective exploration area is about 2.05 square kilometers.

(1) In the actual working process, as the communication of the unmanned aerial vehicle host is interfered, the unmanned aerial vehicle can not work normally, the flight detection task of 33 measuring lines is actually completed, the effective detection area is 1.84Km < 2 >, and the total flight detection length is 37950m.

(2) 1 direct current electric method survey line is arranged along a road in a region, the length is 850.0m, 18 survey points are designed, the point distance is 50.0m, the measurement is carried out by adopting a tripolar device, and the pole distance sequence is set as follows: 10. 15, 20, 30, 50, 80, 100, 120, 150, 180, 210, 250m;

(3) The transient electromagnetic measuring line is designed to be the same as the direct current method, 86 measuring points are designed in total, the point distance is 10.0m, the same loop device is adopted for detection, the coil adopts 10 m-10 m multi-turn loops, and the number of turns is 5.

However, observing the electromagnetic field signal of the single component lacks not only the horizontal component magnetic field information, but also is difficult to correct in the distortion area of the magnetic field response, so that the problems of low accuracy, large error and the like of apparent resistivity interpretation result are caused.

High-precision inertial navigation is a device used to obtain coil attitude information because the attitude changes during the working flight after the coil is suspended below the aircraft. Therefore, we need to know the pose information of the coil in real time for the subsequent compensation calculation. Three-component fluxgate sensors are also used for attitude compensation. The three-component magnetic field data are collected, and because the magnetic field data are relatively stable, the three-component magnetic field data are combined with the high-precision inertial navigation attitude data, and the three-component magnetic coil collected data are compensated and calculated.

The three-component electromagnetic coil is arranged below the aircraft, when the aircraft is electrified, an excitation electromagnetic field is generated, then according to the smoke ring effect, the electromagnetic field is emitted to the ground, the ground is used as a conductor, feedback is generated after the electromagnetic field is received, at the moment, the three-component electromagnetic coil is used for collecting a feedback electromagnetic field signal of the ground, the signal is converted into an electric signal, then a resistivity section diagram of the ground (the method is a calculation formula in a project report) is obtained through a receiver, and according to the resistivity section diagram, different strata of the ground can be judged.

When in use, the control mode comprises the following steps:

transmitting, collecting and receiving system parameters

(1) And (3) setting receiving and transmitting parameters: the power of the transmitter is 30KW, the transmitting current is 20-30A, the transmitting system is a ground long-wire electrical source, the length is 1500m, and the fundamental frequency range is adjustable in time domain of 6.25Hz, 12.5Hz and 25 Hz. The time domain duty ratio of the transmitted waveform is adjustable, and the waveform is rectangular wave and frequency domain multi-frequency pseudo-random wave. A transmit waveform record can be provided with a GPS time synchronized time stamp. A specific synchronization procedure is shown in fig. 5.

(2) The acquisition and receiving system is a three-component high-precision electromagnetic sensor, and is used for continuously acquiring the electromagnetic sensor with a sampling rate of 96K. The rotor unmanned aerial vehicle is adopted to carry an electromagnetic sensor, the rotor unmanned aerial vehicle flies in parallel with a transmitting source to collect induced electromotive force response, the flying height is smaller than 50m (determined according to the fluctuation condition of the terrain in a measuring area), and the flying speed is smaller than 8m/s.

1) Three-component receiving sensor

Coil type: induction coil

Coil sensitivity: 0.15 mv/nT.Hz

Filter bandwidth: time domain 60kHz, frequency domain 200Hz

Noise level: less than 3nV/Hz

The components are as follows: three components (variable vertical effective area, minimum effective area greater than 200 square meters)

Sensor size requirements: a side length of 50cm, a cube; weight: not more than 5KG

5.1 data acquisition

In the data acquisition process, the unmanned aerial vehicle is used for carrying a three-component electromagnetic sensor and a data acquisition transmission control system, and flight acquisition is carried out on a set route. The process comprises the following steps: unmanned plane inspection, electromagnetic sensor carrying, route setting, take-off debugging, flight acquisition, navigation landing, data inspection, data recovery and other processes, and the specific situation is shown in fig. 6.

5.2 data processing

(1) And (3) data quality analysis: because the working mode of the ground-to-air transient electromagnetic method is different from that of the ground transient electromagnetic method, the number of measuring points is huge, but when data acquisition is carried out on a single measuring point, a method of multiple superposition cannot be used, and the data quality cannot be evaluated during data acquisition. Therefore, for the ground-air transient electromagnetic data obtained in the present area, the first step needs to perform quality evaluation of the data, and screen and remove bad pixels in the data, otherwise, it may affect subsequent data processing and apparent resistivity definition, and false anomalies occur, further affecting the interpretation stage.

(2) Data space filtering noise reduction, time channel pumping and manual smoothing: the density of the collected measuring points is relatively high, and two adjacent measuring points have relatively small space distance, so that the three-point filtering algorithm is adopted to carry out the space filtering noise reduction of the data. Since the acquisition time of the initial data is relatively large, the calculation time is relatively large when the global apparent resistivity is defined, so that the data is filtered, and then the time channel is extracted, the logarithmic equidistant mode is adopted, and 20 channels are used as the time extraction channels. However, even if the extraction and spatial filtering are performed, the data may still have possible noise and other interferences, and in late stage, the response of a part of the measuring points may send larger jumps, and these events may affect the definition of the global apparent resistivity, so that the data is displayed by using the multi-track map, and the partial time-track data of a single measuring point is manually smoothed according to the overall characteristics of the multi-track map and the ground-air transient electromagnetic response rule.

(3) Mutual inductance correction: because the electromagnetic field emitted by the emitting source is high-power and the receiving and transmitting distance is short, the mutual inductance influence of the receiving coil exists in the original data, and the intensity of the mutual inductance influence is changed along with the difference of the receiving and transmitting distance, so that the mutual inductance correction is carried out for the effectiveness of the result. And carrying out forward modeling according to the acquired data, calculating forward responses of all the measuring points, correcting the observed data according to the ground-air transient electromagnetic response data calculated by forward modeling of each measuring point, and finally obtaining a correction coefficient for each single measuring point. The data preprocessing flow is shown in fig. 7.

Data interpretation

And marking the abnormal range of the reaction in the multi-channel section diagram and the inversion apparent resistivity section diagram corresponding to each measuring line on the detection result diagram. If similar anomalies appear in the corresponding positions of the same measuring points on the adjacent measuring lines, the adjacent measuring lines are marked as an anomaly area. If only one measuring line has an abnormality or has a smaller abnormality range, the problem of interference of the suspended electromagnetic method is considered, and the abnormal area is not interpreted.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (6)

1. The receiver for the electromagnetic acquisition system of the ground unmanned aerial vehicle is characterized in that a semi-aviation electromagnetic system of a magnetic coupling source or a galvanic coupling source transmitting system is used as an airborne receiving system on the ground; the airborne receiving system acquires full time sequence data and acquires frequency domain data besides time domain data; the receiver consists of a nose cone, a high-precision inertial navigation, a three-component fluxgate sensor, a first protective sleeve, a circuit board, a power supply assembly, a three-component electromagnetic coil, a second protective sleeve and a tail wing, wherein the nose cone is sequentially connected with the first protective sleeve, the second protective sleeve and the tail wing from top to bottom to form an outer shell of the receiver, the nose cone is connected with the first protective sleeve, the first protective sleeve is connected with the second protective sleeve, the inside of the receiver is hollow, the high-precision inertial navigation, the three-component fluxgate sensor, the circuit board, the power supply assembly and the three-component electromagnetic coil are arranged from top to bottom, and the second protective sleeve is connected with the tail wing; wherein:

providing three-axis attitude data in the same direction as the three-component fluxgate sensor and the three-component electromagnetic coil to calibrate the attitudes of the three-component fluxgate sensor and the three-component electromagnetic coil;

the three-component fluxgate sensor provides three-component magnetic field data, and performs magnetic field data direction calibration in the electromagnetic data on the three-component electromagnetic coil;

the first protective sleeve is used for reducing impact and vibration to the circuit board and the power supply assembly during landing;

the circuit board and the power supply component are used for supplying power and stabilizing voltage;

the three-component electromagnetic coil is used for collecting three-component electromagnetic signals and respectively carrying out attitude and magnetic field change direction calibration through the high-precision inertial navigation and the three-component fluxgate sensor;

the second protective sleeve is used for balancing and stabilizing the protection function of the tail part of the whole receiver;

and the tail fin is used for stabilizing the azimuth and the counterweight effect.

2. A receiver for an electromagnetic acquisition system of a ground-based unmanned aerial vehicle according to claim 1, wherein the receiver is suspended in the lower part of the aircraft by means of a three-point hook on the outer housing of the receiver for avoiding the interference of the aircraft.

3. The receiver for an electromagnetic acquisition system of an unmanned aerial vehicle according to claim 1, wherein the three directions of the high-precision inertial navigation, the fluxgate and the three-component electromagnetic coil are completely consistent, and are fixedly connected by adopting a rigid non-metal PVC or nylon structural member.

4. The receiver for an electromagnetic acquisition system of an unmanned aerial vehicle according to claim 1, wherein the components of the receiver are fixedly connected by a metal-free nylon or PVC bracket, and the circuits are connected by cable signal wires.

5. The receiver for the electromagnetic acquisition system of the ground-to-air unmanned aerial vehicle according to claim 1, wherein the three-component electromagnetic coil is specifically structured to acquire electromagnetic signals in the x\y\z direction by means of three electromagnetic coils which are relatively perpendicular to each other, and each coil is required to be powered by a circuit board and a power supply assembly and is fixed on a nonmetal fixing plate.

6. The receiver for an electromagnetic acquisition system of a ground-to-air unmanned aerial vehicle of claim 1, wherein the outer shell material of the receiver is formed by combining PVC and/or polyester braze-free metal materials.

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