Aviation magnetic force vertical gradient measurement device suitable for unmanned aerial vehicle

Abstract

The device comprises an aeromagnetic compensation recording instrument, two preamplifiers and a radar altimeter, the aeromagnetic compensation recording instrument, the two preamplifiers and the radar altimeter are mounted at the bottom of the unmanned aerial vehicle, the preamplifiers and the radar altimeter are in communication connection with the aeromagnetic compensation recording instrument, and a suspension base is mounted at the bottom of the unmanned aerial vehicle. The suspension base is in shaft connection with a hanging rod through a first motor, the middle portion and the lower portion of the hanging rod are in shaft connection with mounting plates through second motors respectively, the mounting plates are provided with cesium optical pump magnetometers, and the cesium optical pump magnetometers are in communication connection with the aeromagnetic compensation recording instrument. The method can overcome the defects in the prior art, and is suitable for carrying out aviation magnetic force vertical gradient measurement in a complex environment.

Description

Technical Field

[0001] The invention relates to the technical field of aeromagnetic measurement, in particular to an aeromagnetic vertical gradient measurement device suitable for unmanned aerial vehicles. Background Art

[0002] With the gradual maturity of aeromagnetic measurement modification systems based on fixed-wing drones, composite-wing drones, and multi-rotor drones in recent years, the use of drones for aeromagnetic measurement has become the mainstream. Compared with total field measurement, magnetic field vertical gradient data has many advantages. First, magnetic field vertical gradient measurement can effectively eliminate the influence of daily variation and distant source interference magnetic field, and improve magnetic measurement accuracy; second, the vertical gradient of the magnetic field only changes sharply near the magnetic interface on the profile, which is easy to identify, and can quickly and accurately delineate the boundary position and occurrence, which is used for geological mapping, which has greater advantages than total field measurement; third, the effective exploration range of magnetic field vertical gradient measurement is different from that of total field measurement, and the effective cross-sectional area ratio is about 0.23:1.0, so vertical gradient measurement can effectively highlight shallow source anomalies. The measurement device for measuring total field data previously developed by our unit uses a rope to suspend the cesium optical pump magnetometer, which makes it easy for the cesium optical pump magnetometer to deviate under the action of inertia when performing high-speed measurements in complex environments, resulting in measurement errors. In addition, the horizontally installed probe rod is not convenient for the obstacle avoidance flight of the drone, which directly affects the application scope of this device. Therefore, a more flexible measurement device that is convenient for accurately measuring the vertical gradient data of the magnetic field is urgently needed. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an aeromagnetic vertical gradient measuring device suitable for unmanned aerial vehicles, which can solve the shortcomings of the prior art and is suitable for aeromagnetic vertical gradient measurement in complex environments.

[0004] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0005] The invention discloses an aeromagnetic vertical gradient measuring device suitable for an unmanned aerial vehicle, comprising an aeromagnetic compensation recorder, two preamplifiers and a radar altimeter installed at the bottom of the unmanned aerial vehicle, wherein the preamplifier and the radar altimeter are communicatively connected with the aeromagnetic compensation recorder, a suspension base is installed at the bottom of the unmanned aerial vehicle, a hanging rod is connected to the suspension base via a first motor shaft, a mounting plate is connected to the middle and lower parts of the hanging rod via a second motor shaft respectively, a cesium optical pump magnetometer is installed on the mounting plate, and the cesium optical pump magnetometer is communicatively connected with the aeromagnetic compensation recorder.

[0006] Preferably, a barometric altimeter is also installed at the bottom of the drone, and the barometric altimeter is communicatively connected to the aeromagnetic compensation recorder.

[0007] Preferably, the suspension base includes a base plate fixed on the drone, a plurality of pressure sensors are arranged in a ring on the edge of the bottom surface of the base plate, a buffer spring is arranged in the center of the base plate, a rubber hydraulic cavity is arranged on the outside of the buffer spring, the buffer spring and the bottom of the rubber hydraulic cavity are connected to the first motor, and the outer wall of the rubber hydraulic cavity is crimped to the sensing end of the pressure sensor.

[0008] Preferably, the inner wall of the rubber hydraulic cavity is provided with a plurality of arc-shaped protrusions, which are inserted into the gaps of the buffer springs, and two rubber ejector pins are symmetrically provided on the tops of the arc-shaped protrusions, which are clamped on the inner sides of the buffer springs.

[0009] Preferably, the gap between two rubber ejector pins on the same arc-shaped protrusion is maintained at 1.5-2 mm, and the gap between two adjacent rubber ejector pins on adjacent arc-shaped protrusions is maintained at 0.3-0.5 mm.

[0010] Preferably, a rubber sheath is provided between the substrate and the first motor, and transversely woven Kevlar fibers are provided inside the rubber sheath.

[0011] Preferably, the hanging rod is provided with a plurality of through holes, and the second motor is mounted on the through holes.

[0012] Preferably, a shock-absorbing plate is arranged between the through hole and the second motor.

[0013] The beneficial effects brought about by adopting the above technical solution are: the present invention simplifies the structure of the existing total field measurement device, focuses on optimizing and upgrading the suspension mechanism of the cesium optical pump magnetometer, and improves the convenience of aviation magnetic vertical gradient measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of a specific implementation mode of the present invention (flight measurement state).

[0015] Figure 2 It is a cross-sectional view of a suspension base in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0016] Reference Figure 1-2The aeromagnetic vertical gradient measuring device disclosed in the present invention comprises an aeromagnetic compensation recorder 1, two preamplifiers 2, a radar altimeter 3 and a barometric altimeter 4 installed at the bottom of a UAV. The preamplifier 2, the radar altimeter 3 and the barometric altimeter 4 are communicatively connected with the aeromagnetic compensation recorder 1. A suspension base 5 is installed at the bottom of the UAV. A hanging rod 7 is connected to the suspension base 5 through the shaft of a first motor 6. The hanging rod 7 is provided with a plurality of through holes 19. The middle and lower parts of the hanging rod 7 are respectively connected with a mounting plate 9 through the shaft of a second motor 8. The second motor 8 is installed on the through hole 19. A shock absorbing plate 20 is provided between the through hole 19 and the second motor 8. A cesium optical pump magnetometer 10 is installed on the mounting plate 9. The cesium optical pump magnetometer 10 is communicatively connected with the aeromagnetic compensation recorder 1. In view of the characteristics of the vertical gradient data of the magnetic field, we removed the transversely installed probe rod on the basis of the existing total field measurement device, improved the flexibility of the obstacle avoidance flight of the UAV, and changed the suspension mode of the cesium optical pump magnetometer 10 from the original flexible suspension of the rope to the rigid suspension of the hanging rod, which effectively reduced the inertial offset of the cesium optical pump magnetometer 10 when the UAV changes speed and turns. When not in use, the hanging rod 7 is stored parallel to the bottom surface of the UAV. After the UAV takes off to a safe height, the first motor 6 drives the hanging rod 7 to fold downward so that the hanging rod 7 is perpendicular to the bottom surface of the UAV, and then the measurement angle of the cesium optical pump magnetometer 10 is adjusted by the second motor 8 according to the measurement needs. The opening design of the hanging rod 7 can not only reduce the weight of the suspension mechanism, but also facilitate the installation of the second motor 8. The shock-absorbing plate 20 can effectively reduce the vibration transmitted from the hanging rod 7 to the cesium optical pump magnetometer 10. The radar altimeter 3 and the barometric altimeter 4 are used to double calibrate the measured height to ensure the measurement accuracy.

[0017] The suspension base 5 includes a base plate 11 fixed on the drone, and a plurality of pressure sensors 12 are arranged in a ring on the bottom edge of the base plate 11. A buffer spring 13 is arranged at the center of the base plate 11, and a rubber hydraulic chamber 14 is arranged outside the buffer spring 13. The bottom of the buffer spring 13 and the rubber hydraulic chamber 14 are connected to the first motor 6, and the outer wall of the rubber hydraulic chamber 14 is crimped to the sensing end of the pressure sensor 12. The inner wall of the rubber hydraulic chamber 14 is provided with a plurality of arc-shaped protrusions 15, and the arc-shaped protrusions 15 are inserted into the gap of the buffer spring 13. Two rubber ejector pins 16 are symmetrically arranged on the top of the arc-shaped protrusions 15, and the rubber ejector pins 16 are clamped on the inner side of the buffer spring 13. The gap between the two rubber ejector pins 16 on the same arc-shaped protrusion 15 is maintained at 1.5-2 mm, and the gap between the two adjacent rubber ejector pins 16 on the adjacent arc-shaped protrusions 15 is maintained at 0.3-0.5 mm. A rubber sheath 17 is provided between the substrate 11 and the first motor 6, and a transversely woven Kevlar fiber 18 is provided inside the rubber sheath 17. Due to the rigid suspension structure, the shaking amplitude of the drone will be amplified by the hanging rod 7, and the vibration will be directly transmitted to the cesium optical pump magnetometer 10 through the hanging rod 7. The shock-absorbing sheet 20 is mainly used to buffer and absorb high-frequency vibrations, and cannot buffer and absorb low-frequency and large-amplitude vibrations. In order to solve this problem, we set a buffer spring 13 and a rubber hydraulic chamber 14 between the hanging rod 7 and the drone to buffer large-amplitude shaking / vibration. At the same time, the swing of the hanging rod 7 relative to the drone will squeeze the corresponding position of the rubber hydraulic chamber 14. The direction and magnitude of this squeezing force are detected by the pressure sensor 12 and fed back to the control system of the drone, so that the drone can realize closed-loop feedback control of the posture of the hanging rod 7, thereby effectively reducing the shaking of the hanging rod 7 caused by the adjustment of the flight posture of the drone. When the buffer spring 13 is compressed, it will squeeze the arc-shaped protrusion 15, thereby using hydraulic pressure to damp the buffer spring 13, absorbing the vibration energy of the buffer spring 13, and preventing the buffer spring 13 from continuously vibrating back and forth. The rubber top pin 16 is not only used to clamp and install the rubber hydraulic chamber 14 and the buffer spring 13, but also can limit the buffer spring 13 when the buffer spring 13 is lateral bent and over-compressed. The rubber sheath 17 is used to protect the buffer spring 13 and the rubber hydraulic chamber 14, and at the same time can further improve the lateral support strength of the suspension base 5, and prevent the hanging rod 7 from shaking significantly when the UAV's flight posture changes.

[0018] In addition, in terms of material selection, the suspension base 5, the hanging rod 7, the shock-absorbing plate 20 and the motor are all made of non-magnetic or weakly magnetic materials to reduce their interference with the aeromagnetic vertical gradient measurement.

[0019] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0020] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An aeromagnetic vertical gradient measuring device suitable for an unmanned aerial vehicle, comprising an aeromagnetic compensation recorder (1), two preamplifiers (2) and a radar altimeter (3) installed at the bottom of the unmanned aerial vehicle, wherein the preamplifier (2) and the radar altimeter (3) are communicatively connected to the aeromagnetic compensation recorder (1), and characterized in that: A suspension base (5) is installed at the bottom of the drone, a hanging rod (7) is connected to the suspension base (5) via a first motor (6) axis, a mounting plate (9) is connected to the middle and lower parts of the hanging rod (7) via a second motor (8) axis, a cesium optical pump magnetometer (10) is installed on the mounting plate (9), and the cesium optical pump magnetometer (10) is communicatively connected to an aeromagnetic compensation recorder (1).

2. The aerial magnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 1, characterized in that: A barometric altimeter (4) is also installed at the bottom of the drone, and the barometric altimeter (4) is communicatively connected with the aeromagnetic compensation recorder (1).

3. The aerial magnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 1, characterized in that: The suspension base (5) comprises a base plate (11) fixed on the drone, a plurality of pressure sensors (12) are arranged in a ring shape on the bottom edge of the base plate (11), a buffer spring (13) is arranged at the center of the base plate (11), a rubber hydraulic chamber (14) is arranged on the outside of the buffer spring (13), the bottom of the buffer spring (13) and the rubber hydraulic chamber (14) are connected to the first motor (6), and the outer wall of the rubber hydraulic chamber (14) is crimped to the sensing end of the pressure sensor (12).

4. The aerial magnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 3, characterized in that: The inner wall of the rubber hydraulic cavity (14) is provided with a plurality of arc-shaped protrusions (15), the arc-shaped protrusions (15) are inserted into the gaps of the buffer spring (13), and two rubber ejector pins (16) are symmetrically provided on the top of the arc-shaped protrusions (15), and the rubber ejector pins (16) are clamped on the inner side of the buffer spring (13).

5. The aeromagnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 4, characterized in that: The gap between two rubber ejector pins (16) on the same arc-shaped protrusion (15) is maintained at 1.5-2 mm, and the gap between two adjacent rubber ejector pins (16) on adjacent arc-shaped protrusions (15) is maintained at 0.3-0.5 mm.

6. The aerial magnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 5, characterized in that: A rubber sheath (17) is arranged between the substrate (11) and the first motor (6), and transversely woven Kevlar fibers (18) are arranged inside the rubber sheath (17).

7. The aeromagnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 1, characterized in that: The hanging rod (7) is provided with a plurality of through holes (19), and the second motor (8) is mounted on the through holes (19).

8. The aerial magnetic vertical gradient measuring device suitable for unmanned aerial vehicles according to claim 7, characterized in that: A shock absorbing sheet (20) is provided between the through hole (19) and the second motor (8).

Images