An integration method of aeromagnetic horizontal gradient measurement system based on Rainbow 4 UAV

Abstract

The present invention relates to the field of aeromagnetic technology, and discloses an aeromagnetic horizontal gradient measurement system integration method based on the Rainbow 4 UAV, which includes the following steps: S1: installation of magnetic sensors and electronic acquisition units; S2: installation of attitude measuring instruments; S3: installation of GPS antennas; S4: installation of radio altimeter host and antennas; S5: laying of cables; S6: commissioning and installation of power supply equipment. The present invention uses the Rainbow 4 UAV as a flight platform. The Rainbow 4 is a fixed-wing UAV with a long flight time. During the integration of the aeromagnetic gradient system, only left and right magnetic sensors are installed, so the integration process is simpler, the cost is lower, and the safety is higher. The integrated aeromagnetic horizontal gradient measurement system based on the Rainbow 4 UAV has the advantages of high stability and low modification cost, and the dynamic fourth-order difference of the horizontal gradient is better than ±2pT / m.

Description

Technical Field

[0001] The invention relates to the field of aeromagnetic technology, and in particular to an aeromagnetic horizontal gradient measurement system integration method based on a Rainbow 4 UAV. Background Art

[0002] Multi-parameter measurement represented by aeromagnetic gradient has gradually become an important development direction of high-precision airborne geophysical exploration. Canada has carried out aeromagnetic gradient measurement since the 1970s. At present, aeromagnetic gradient measurement systems have been integrated on aircraft platforms such as Yun-5 and Yun-12, but drones have advantages such as long flight time and light weight, so integration into existing drones is the current trend.

[0003] Advantages of UAVs: Since UAVs do not have pilots, they can perform dangerous tasks that exceed the physiological limits of pilots, such as long flight time, large maneuvering flights, or performing tasks in dangerous areas such as severe weather conditions and battlefields. Modern UAVs have long surpassed the concept of so-called "remote control aircraft", and their advantages in performing military missions have also made many countries attach great importance to them.

[0004] In April 2019, the Rainbow-4 UAV completed its first aerial geophysical exploration test flight in a place in the northwest.

[0005] Prior art 1:

[0006] The existing literature (An Zhanfeng, Wang Ping, Duan Shuling, et al. Experimental measurement of domestic aeromagnetic full-axis gradient exploration system [J]. Geophysical and Geochemical Exploration, 2016, 40(2): 370-373.) provides a method using the Y-12 aircraft as a carrier, such as Figure 1 The main modifications include: ① installing 4 magnetic probes on the wings and tail of the aircraft, such as Figure 1 1. Install the left and right heads and the upper and lower probes in the aircraft; 2. Install the full-axis gradiometer, compensation collection system, attitude indicator and other equipment inside the cabin; 3. Install the GPS navigation locator antenna on the top of the aircraft cabin and the altimeter on the belly of the aircraft.

[0007] The defects and causes of the prior art are analyzed as follows:

[0008] The Y-12 aircraft has a short flight endurance, high cost, and the measurement process is affected by human factors. The Y-12 has not been used to fly over the aeromagnetic gradient since 2016.

[0009] The aeromagnetic gradient measurement system is integrated into the Y-12 aircraft. The Y-12 is a manned aircraft. The flight posture and flight time caused by human factors during the flight measurement will affect the aeromagnetic gradient measurement effect. During the integration of the aeromagnetic gradient system, due to the large body of the Y-12 aircraft, the integrated aeromagnetic gradient system is more expensive and cumbersome, and has greater safety hazards. Summary of the invention

[0010] In order to overcome or alleviate one or more of the above technical problems, the purpose of the present invention is to provide an integrated method for an aeromagnetic horizontal gradient measurement system based on the Rainbow 4 UAV. The method uses the Rainbow 4 UAV as a flight platform. The Rainbow 4 is a fixed-wing UAV. According to the requirements of the aeromagnetic gradient system, magnetic sensors are installed on both wings of the aircraft, and aeromagnetic gradient data collection and compensation system, power supply panel, GPS system and other aeromagnetic gradient system components are installed in the UAV payload cabin to complete the modification of the UAV power supply system, the information exchange between the UAV flight control system and the aeromagnetic collection and compensation system, and the line layout. In addition, a navigation and positioning system is installed on the top of the aircraft.

[0011] The present invention provides the following technical solutions:

[0012] An aeromagnetic horizontal gradient measurement system integration method based on Rainbow 4 UAV comprises the following steps:

[0013] S1: Installation of magnetic sensors and electronic acquisition units. A magnetic sensor and an electronic acquisition unit are installed on both sides of the wings of the Rainbow 4 UAV. The magnetic sensor is used to sense the geomagnetic field signal. The electronic acquisition unit is used to convert the collected geomagnetic field signal into an electrical signal and is connected to the aeromagnetic collection system and compensation system through a cable.

[0014] S2: Installation of an attitude measuring instrument, wherein the attitude measuring instrument is installed in the payload cabin of the Rainbow 4 UAV, the longitudinal axis of the attitude measuring instrument is placed in the longitudinal axis plane of the aircraft, and the horizontal line of the attitude measuring instrument is consistent with the horizontal line of the earth when the aircraft is flying level; the attitude measuring instrument is connected to the aeromagnetic recording system and the compensation system through a cable;

[0015] S3: Installation of GPS antenna. The GPS antenna is fixed on the outer skin of the payload cabin of the Rainbow 4 UAV. The feeder is introduced into the cabin and connected to the aeromagnetic collection system and compensation system through cables.

[0016] S4: Installation of a radio altimeter host and antenna. The radio altimeter host is located in the cabin of the Rainbow 4 UAV. The radio altimeter host is connected to the aeromagnetic collection system and compensation system through wires. The onboard equipment of the Rainbow 4 UAV includes a radio altimeter antenna. The radio altimeter antenna signal is introduced into the aeromagnetic collection system and compensation system.

[0017] S5: Cable laying: except for the power cables, cables are laid to the corresponding instruments in the payload cabin of the Rainbow 4 UAV;

[0018] S6: Debugging and installation of power supply equipment. The power supply of the aeromagnetic horizontal gradient measurement system is a two-wire power supply. The ground wire is drawn from the generator of the Rainbow 4 UAV, and a set of positive power lines are drawn from the bus bar. A distribution box is set up in the Rainbow 4 UAV payload cabin to provide three sets of 28V DC power supplies, and terminal wiring is used.

[0019] According to some embodiments, in step S1, the magnetic sensors are all disposed in a teardrop-shaped fairing.

[0020] According to some implementations, in step S5, the power line and the data line are both installed in a closed routing manner.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention provides an aeromagnetic horizontal gradient measurement system integration method based on the Rainbow 4 UAV. The method uses the Rainbow 4 UAV as a flight platform. The Rainbow 4 is a fixed-wing UAV with a long flight time. During the integration of the aeromagnetic gradient system, only left and right magnetic sensors are installed. The integration process is simpler, saves integration time, and has a lower cost. In addition, the line installation method in the measurement system adopts a closed wiring method, which does not have any impact on the body shape, thereby enhancing flight safety.

[0023] 2. A water drop head fairing is used at the probe installation position at the wing tip, which makes the airflow at the wing tip smoother and enhances the flight stability and safety of the aircraft wing;

[0024] 3. The integrated aeromagnetic horizontal gradient measurement system based on the Rainbow 4 UAV has the advantages of high stability and low modification cost. The dynamic fourth-order difference of the horizontal gradient is better than ±2pT / m, which has reached the international leading level. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the installation of an integrated aeromagnetic gradient measurement system using a Y-12 aircraft as a carrier provided in the background technology of the present application.

[0026] Figure 2 It is a schematic diagram of the structure of an aeromagnetic horizontal gradient measurement system to be modified provided in an embodiment of the present invention.

[0027] Figure 3 A schematic diagram of the installation of an aeromagnetic horizontal gradient measurement system based on the Rainbow 4 UAV provided in an embodiment of the present invention.

[0028] Figure 4 A flowchart of an aeromagnetic horizontal gradient measurement system integration method based on the Rainbow 4 UAV provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the embodiments and drawings, but it should be understood that the embodiments and drawings are only used to exemplify the present invention and do not constitute any limitation on the protection scope of the present invention. All reasonable changes and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0030] According to the principle of aeromagnetic full-axis gradient measurement, the installation of magnetic sensors requires the connection between the two wing probes, the connection between the upper and lower probes, and the aircraft to be on the same horizontal plane. This modification is difficult and has high requirements. The modification accuracy will directly affect the final measurement effect.

[0031] Therefore, the probe installation position is required to have low magnetic interference, be able to achieve the purpose of gradient measurement, and meet certain geometric distribution relationships between the probes, and minimize the impact on the aircraft's center of gravity and aerodynamic performance. In addition, the tail support structure should have sufficient rigidity when connected to the aircraft, and all components should be made of non-magnetic materials.

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] Example 1

[0034] like Figure 2 The aeromagnetic horizontal gradient measurement system to be modified includes an aeromagnetic collection and compensation system, which are electrically connected to the magnetic sensor, flight control system, and GPS respectively. The magnetic sensor has two probes, namely the left probe and the right probe.

[0035] The aeromagnetic collection and compensation system is an existing product. The AGS-863 aeromagnetic collection and compensation system can be selected. The aeromagnetic collection collects the data measured by each aeromagnetic sensor, including aircraft attitude, altitude information and GPS information; the compensation is an error correction system because the aircraft body will have magnetic interference on the measurement.

[0036] Magnetic sensors are used to detect magnetic fields; the flight control system is used to record aircraft attitude, detect air pressure altitude, radar altitude and other information; GPS is used for aircraft positioning.

[0037] like Figure 4 The aeromagnetic horizontal gradient measurement system integration method based on the Rainbow 4 UAV provided in this embodiment includes the following steps:

[0038] S1: Installation of magnetic sensor and electronic acquisition unit;

[0039] A magnetic sensor (left and right probes) and an electronic collection unit are installed on each side of the wings of the Rainbow 4 UAV.

[0040] The electronic acquisition unit is a product that acts as a transition between the magnetic sensor and the recording system. It is used to collect the signals of the magnetic sensor and is connected to its aeromagnetic recording system and compensation system through cables.

[0041] S2: Installation of attitude measuring instrument;

[0042] The attitude measuring instrument belongs to the flight control system and is used to record the aircraft attitude. Changes in the aircraft attitude will cause errors in the measurement results, which require later corrections. It is connected to the aeromagnetic recording and compensation system through cables;

[0043] The attitude measuring instrument needs to be installed in the payload cabin of the UAV, with the longitudinal axis of the attitude measuring instrument placed in the plane of the longitudinal axis of the aircraft, and the horizontal line of the attitude measuring instrument should be consistent with the horizontal line of the earth when the aircraft is flying level;

[0044] S3: Installation of GPS antenna;

[0045] The GPS antenna is connected to the aeromagnetic collection and compensation system through wires. The GPS antenna can be fixed on the outer skin of the UAV payload cabin, and the feeder is introduced into the cabin. Both the antenna and the feeder should be easy to disassemble.

[0046] S4: Installation of radio altimeter host and antenna;

[0047] The radio altimeter host belongs to the flight control system and is used to record the radio flight altitude. Changes in altitude will affect the measurement results. The altitude information will be used in subsequent data processing. It is connected to the aeromagnetic collection and compensation system through wires and is installed in the cabin.

[0048] The onboard equipment of the Rainbow 4 UAV includes a radio altimeter antenna, which can directly introduce the signal into the aeromagnetic collection and compensation system.

[0049] S5: Cable laying;

[0050] In addition to the power cord, cables need to be laid to the instruments in the payload compartment. The total weight of the cables is about 30 kg.

[0051] S6: commissioning and installation of power supply equipment;

[0052] The power supply of the aeromagnetic horizontal gradient measurement system requires a two-wire power supply, that is, a ground wire is drawn from the generator of the drone, a set of power (positive line) is drawn from the bus bar, and a distribution box is set in the payload cabin of the drone. Three sets of 28V DC power supplies are provided, and the power leads are required to have a small enough resistance (the inner core diameter of the power line is not less than 8mm), and the terminal wiring is used.

[0053] The power supply here refers to the UAV supplying power to the aeromagnetic horizontal gradient measurement system. As long as the aircraft is started, it can be powered continuously. In terms of the UAV's flight time, the Rainbow 4 UAV can fly for at least thirty-five hours with a full tank of fuel.

[0054] After the modification, the aircraft and instrument system firstly undergo various tests such as stall speed, stall characteristics, longitudinal static stability, lateral static stability, vibration and buffeting to verify the rationality of the whole system design and whether the functions of each subsystem meet the design requirements. So far, the aeromagnetic gradient measurement equipment based on the Rainbow 4 UAV and its auxiliary equipment constitute a complete aeromagnetic horizontal gradient measurement system for aeromagnetic gradient survey.

[0055] Example 2

[0056] This embodiment is an aeromagnetic horizontal gradient measurement system integration method based on the Rainbow 4 UAV provided in Example 1. Through the implementation of the integration project, the integration of the aeromagnetic horizontal gradient measurement system based on the Rainbow 4 UAV was completed at a certain airport, and the test flight was completed.

[0057] 1. Measurement principle

[0058] At the flight altitude of aeromagnetic survey, the vertical gradient of the Earth's main magnetic field ranges from 0.015 to 0.03 nT / m, increasing continuously from the equator to the poles. The gradient ranges from 0.005 to 0.003 nT / m, decreasing continuously from the equator to the poles. The gradient anomaly caused by local geological bodies or structures can reach the order of 10 nT / m. The magnetic anomaly gradient can be obtained by measuring the difference in the geomagnetic field using magnetometers with a certain spacing.

[0059] Figure 3 The position relationship of the two magnetometer probes in the measurement system is given, where T L 、T R are the geomagnetic field strengths measured by the left and right probes, respectively. △x and △y are the horizontal and vertical spacings of the magnetic sensors, respectively. △T x , △T y They are the lateral difference and longitudinal difference of the magnetic sensor respectively. They are expressed as:

[0060]

[0061] The aeromagnetic horizontal gradient measurement system includes the displacement of the horizontal gradient formed by the left and right probes of the aircraft in the flight direction. Gradient measurement has extremely high requirements for the accuracy of the magnetometer. Inconsistency or instability between magnetometers can easily cause false anomalies. Unlike ground gradient measurement, aeromagnetic gradient measurement requires strict time synchronization during system data acquisition. If the Rainbow 4 UAV measures at a speed of 200km / h, the position difference caused by a 0.1s delay in data acquisition is about 6m. The dynamic fourth-order difference of the horizontal gradient is better than ±2pT / m, which is an internationally leading indicator.

[0062] 2. Rainbow 4 UAV aeromagnetic gradient system test flight

[0063] An aeromagnetic gradient test flight was carried out in a certain place. The flight results showed that the aeromagnetic horizontal gradient measurement system integration of the Rainbow 4 UAV met all requirements and basically had aeromagnetic operation capabilities.

[0064] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An integration method of an aeromagnetic horizontal gradient measurement system based on the Rainbow 4 UAV, characterized by: The steps include: S1: Installation of magnetic sensors and electronic acquisition units. A magnetic sensor and an electronic acquisition unit are installed on both sides of the wings of the Rainbow 4 UAV. The magnetic sensor is used to sense the geomagnetic field signal. The electronic acquisition unit is used to convert the collected geomagnetic field signal into an electrical signal and is connected to the aeromagnetic collection system and compensation system through a cable. S2: Installation of an attitude measuring instrument, wherein the attitude measuring instrument is installed in the payload cabin of the Rainbow 4 UAV, the longitudinal axis of the attitude measuring instrument is placed in the longitudinal axis plane of the aircraft, and the horizontal line of the attitude measuring instrument is consistent with the horizontal line of the earth when the aircraft is flying level; the attitude measuring instrument is connected to the aeromagnetic recording system and the compensation system through a cable; S3: Installation of GPS antenna. The GPS antenna is fixed on the outer skin of the payload cabin of the Rainbow 4 UAV. The feeder is introduced into the cabin and connected to the aeromagnetic collection system and compensation system through cables. S4: Installation of a radio altimeter host and antenna. The radio altimeter host is located in the cabin of the Rainbow 4 UAV. The radio altimeter host is connected to the aeromagnetic collection system and compensation system through wires. The onboard equipment of the Rainbow 4 UAV includes a radio altimeter antenna. The radio altimeter antenna signal is introduced into the aeromagnetic collection system and compensation system. S5: Cable laying: except for the power cables, cables are laid to the corresponding instruments in the payload cabin of the Rainbow 4 UAV; S6: Debugging and installation of power supply equipment. The power supply of the aeromagnetic horizontal gradient measurement system is a two-wire power supply. The ground wire is drawn from the generator of the Rainbow 4 UAV, and a set of positive power lines are drawn from the bus bar. A distribution box is set up in the Rainbow 4 UAV payload cabin to provide three sets of 28V DC power supplies, and terminal wiring is used.

2. The method for integrating aeromagnetic horizontal gradient measurement system based on Rainbow 4 UAV according to claim 1 is characterized in that: In step S1, the magnetic sensors are all arranged in a teardrop-shaped fairing.

3. The aeromagnetic horizontal gradient measurement system integration method based on the Rainbow 4 UAV according to claim 1 is characterized by: In step S5, the power line and the data line are both installed in a closed wiring manner.

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