Lightning rod for unmanned aircraft

Abstract

This lightning rod 30 for an unmanned aircraft comprises: a lightning rod part 33; a first stepping motor 31; and a second stepping motor 32 connected to the rotating shaft 311 of the first stepping motor 31 and rotating with a second rotating shaft 321 that crosses the first rotating shaft 311, the lightning rod part 33 being installed on the second rotating shaft 321, and the first stepping motor 31 and the second stepping motor 32 being controlled in rotation angles according to the flight orientation of the unmanned aircraft 20.

Description

Lightning rod for unmanned aircraft

[0001] The present disclosure relates to lightning rods for unmanned aerial vehicles.

[0002] In recent years, unmanned aerial vehicles (drones) have been developing remarkably, and their use in various applications is expanding. As an example of the use of unmanned aerial vehicles, research is being conducted on a system that uses unmanned aerial vehicles to control lightning strikes (Non-Patent Document 1).

[0003] Furthermore, in such systems, unmanned aircraft are subject to direct lightning strikes, and research is also being conducted into technologies to prevent unmanned aircraft from breaking down or being damaged in such situations (Patent Document 1, Non-Patent Document 2).

[0004] International Publication No. 2022 / 102091

[0005] Nippon Telegraph and Telephone Corporation, "Lightning Control and Charging Technology," [online], Internet <URL: https: / / www.rd.ntt / research / SE0010.html> Nippon Telegraph and Telephone Corporation, "Protecting cities from lightning strikes with drones that survive lightning strikes," NTT R&D FORUM-Read to IWON 2022, [online], Internet <URL: https: / / www.rd.ntt / forum / 2022 / doc / E-F01.pdf>

[0006] Patent document 1 proposes enclosing an unmanned aerial vehicle in a metal cage to make it resistant to lightning strikes, while non-patent document 2 proposes installing a lightning rod at the tip of the cage, so that the lightning current that strikes the lightning rod is diverted along the cage frame, and the magnetic fields generated by the lightning current within the cage cancel each other out.

[0007] In Non-Patent Document 2, when the unmanned aerial vehicle is flying horizontally, the lightning rod faces directly upward, so the entire cage is within the lightning rod's protection range. However, when flying in strong winds, the unmanned aerial vehicle and cage may tilt. In this case, Non-Patent Document 2 states that the lightning rod installed on the cage will also tilt, causing part of the cage to leave the lightning rod's protection range, increasing the risk of lightning striking the cage directly rather than the lightning rod. If lightning strikes the cage directly, the large lightning current will flow into the cage frame without being diverted, which could damage the cage frame and reduce the effectiveness of canceling out the magnetic field within the cage.

[0008] The present disclosure has been made in consideration of the above circumstances, and the purpose of the present disclosure is to provide a lightning rod for an unmanned aircraft that points straight up vertically even when the unmanned aircraft is flying at an angle.

[0009] In order to achieve the above-mentioned object, one embodiment of the lightning rod for an unmanned aerial vehicle disclosed herein comprises a lightning rod section, a first stepping motor, and a second stepping motor connected to a first rotational axis of the first stepping motor and rotating on a second rotational axis that intersects with the first rotational axis, wherein the lightning rod section is installed on the second rotational axis, and the rotation angles of the first stepping motor and the second stepping motor are controlled according to the flight attitude of the unmanned aerial vehicle.

[0010] According to the present disclosure, it is possible to provide a lightning rod for an unmanned aircraft that faces straight up vertically even when the unmanned aircraft is flying at an angle.

[0011] FIG. 1 is a diagram showing an unmanned aerial vehicle, a cage, and a lightning rod according to this embodiment. FIG. 2A is a schematic diagram showing an example of a lightning rod 30. FIG. 2B shows an image of the rotation direction of a first stepping motor and a second stepping motor. FIG. 2C is an external view showing an example of a method of connecting a first stepping motor and a second stepping motor. FIG. 3 is an explanatory diagram for explaining control by a control unit. FIG. 4A is a diagram showing the orientation of a lightning rod for an unmanned aerial vehicle flying horizontally. FIG. 4B is a diagram showing the orientation of a lightning rod for an unmanned aerial vehicle flying at an angle. FIG. 5A is a diagram showing a lightning rod according to this embodiment. FIG. 5B is a diagram showing a lightning rod of a comparative example. FIG. 6 is an example of a hardware configuration.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0013] FIG. 1 shows an unmanned aerial vehicle 20 according to this embodiment, a cage 10, and a lightning rod 30 (lightning rod for unmanned aerial vehicles).

[0014] The unmanned aerial vehicle (UAV) 20 is an air vehicle also known as a drone. The unmanned aerial vehicle 20 of this embodiment is enclosed in a metal cage 10 to provide resistance to lightning strikes.

[0015] The cage 10 is a metal shield that receives lightning current from above instead of the unmanned aerial vehicle 20, and is also called a Faraday cage. The cage 10 is disposed around (outside) the unmanned aerial vehicle 20, surrounding the unmanned aerial vehicle 20 at a distance that does not interfere with the flight of the unmanned aerial vehicle 20 located inside. The cage 10 may have, for example, a lattice-like shape using conductors such as wires. The overall shape of the cage 10 may be any shape, such as an ellipse, a sphere, or a polyhedron.

[0016] A lightning rod 30 is installed in the cage 10 of this embodiment. The lightning rod 30 is installed on the top of the cage 10 to protect the unmanned aerial vehicle 20 from lightning strikes. It is preferable to install the lightning rod 30 at the tip of the top of the cage 10. The lightning rod 30 will be described later.

[0017] The cage 10 has an attachment portion 12 for attaching and fixing the cage 10 to the unmanned aerial vehicle 20, and is connected to the unmanned aerial vehicle 20 via the attachment portion 12. The attachment portion 12 is, for example, an insulating rod member, and is connected between one point (part) of the cage 10 and one point (part) of the unmanned aerial vehicle 20. Multiple rod members may be connected to multiple points on the unmanned aerial vehicle 20.

[0018] The cage 10 may also be provided with a conductor cable 13 for conducting the lightning current diverted to the cage 10 via the lightning rod 30 to the ground (such as a circuit breaker, a ground structure, or ground ground).

[0019] With this configuration, even if lightning strikes, the lightning current from the strike is diverted and flows through the lightning rod 30 into the frame of the lattice cage 10, preventing the lightning current from flowing into the unmanned aerial vehicle 20 and preventing damage from a large current to the frame of the cage 10. Furthermore, because magnetic fields caused by the current cancel each other out inside the lattice cage 10, the impact of the lightning current on the unmanned aerial vehicle 20 can be minimized.

[0020] In other words, the Faraday cage effect of the lattice-like cage 10 surrounding the exterior of the unmanned aerial vehicle 20 prevents lightning strikes from penetrating the vicinity of the unmanned aerial vehicle 20. The Faraday cage effect is an effect in which electric lines of force cannot penetrate inside an area surrounded by conductors, blocking the external electric field and making all internal potentials equal.

[0021] 2A is a schematic diagram showing an example of a lightning rod 30 installed in the cage 10. The lightning rod 30 includes a first stepping motor 31, a second stepping motor 32, and a lightning rod portion 33.

[0022] The rotation angles of the first stepping motor 31 and the second stepping motor 32 are controlled according to the flight attitude of the unmanned aerial vehicle 20 .

[0023] Specifically, the first stepping motor 31 rotates at an arbitrary angle (θ1) by driving the first rotation shaft 311 under the control of the control unit 34. In the illustrated example, the first rotation shaft 311 of the first stepping motor 31 is oriented vertically.

[0024] The second stepping motor 32 is connected to the first rotation shaft 311 of the first stepping motor 31 and rotates on a second rotation shaft 321 that intersects with the first rotation shaft 311. Specifically, the second stepping motor 32 rotates by an arbitrary angle (θ2) by driving the second rotation shaft 321 under the control of the control unit 34. In the illustrated example, the second rotation shaft 321 of the second stepping motor 32 is horizontal. Note that the first rotation shaft 311 and the second rotation shaft 321 are not limited to this.

[0025] 2B shows an image of the rotation directions of the first stepping motor 31 and the second stepping motor 32. The first stepping motor 31 rotates by an arbitrary angle (θ1) in the XY plane under the control of the control unit 34. The second stepping motor 32 rotates by an arbitrary angle (θ2) in the YZ plane under the control of the control unit 34.

[0026] As shown in FIG. 2C, the second stepping motor 32 may be connected to the first stepping motor 31 using a mounting bracket 39 such as a bracket.

[0027] The lightning rod unit 33 is mounted on the second rotation shaft 321 of the second stepping motor 32. By adjusting the rotation angles of the first stepping motor 31 and the second stepping motor 32 in accordance with the flight attitude of the unmanned aerial vehicle 20, the lightning rod unit 33 mounted on the second rotation shaft 321 can always be directed vertically upward.

[0028] The lightning rod 30 of this embodiment may include a control unit 34. The control unit 34 controls the first stepping motor 31 and the second stepping motor 32. The control unit 34 is connected to the first stepping motor 31 and the second stepping motor 32 via signal lines for transmitting control signals. The control unit 34 may be mounted inside the unmanned aerial vehicle 20. Alternatively, the control unit 34 may be located outside the unmanned aerial vehicle 20, near the first stepping motor 31 and the second stepping motor 32.

[0029] 3 is an explanatory diagram for explaining the control of the control unit 34. In the illustrated example, the control unit 34 calculates the angles (θ1, θ2) at which the first stepping motor 31 and the second stepping motor 32 are to be rotated, based on the pitch angle, yaw angle, and roll angle that indicate the flight attitude (inclination) of the unmanned aerial vehicle 20. The control unit 34 then rotates the first stepping motor 31 and the second stepping motor 32 by the calculated angles (θ1, θ2).

[0030] The control unit 34 may, for example, acquire the pitch angle, yaw angle, and roll angle from a flight controller 21 installed on the unmanned aerial vehicle 20.

[0031] The flight controller 21 controls the flight attitude of the unmanned aerial vehicle 20. Specifically, the flight controller 21 has various sensors 22 such as a gyro sensor, and an attitude control unit 23. The attitude control unit 23 collects measurements (sensor values) taken by the sensors and controls the flight attitude in real time to ensure stable flight of the unmanned aerial vehicle 20. Here, the attitude control unit 23 outputs the three-axis rotation angles (pitch angle, yaw angle, and roll angle) measured by the gyro sensor 22 to the control unit 34 in real time (constantly). The flight controller 21 and the control unit 34 are connected via signal lines.

[0032] The control unit 34 calculates the angles (θ1, θ2) by which the first stepping motor 31 and the second stepping motor 32 are rotated based on the rotation angles of the three axes input in real time, and drives the first stepping motor 31 and the second stepping motor 32. That is, the control unit 34 calculates the control amounts for the first stepping motor 31 and the second stepping motor 32 so that the lightning rod unit 33 installed on the second stepping motor 32 faces directly upward in the vertical direction, and controls (adjusts) the first stepping motor 31 and the second stepping motor 32 using the control amounts.

[0033] The control unit 34 calculates the control amounts of the first stepping motor 31 and the second stepping motor 32 in real time based on the rotation angles of the three axes input in real time, and adjusts the first stepping motor 31 and the second stepping motor 32, so that the lightning rod unit 33 can always be pointed straight up even if the flight attitude of the unmanned aircraft 20 suddenly changes.

[0034] The control unit 34 basically rotates the first stepping motor 31 and the second stepping motor 32 at angles that cancel out the input roll angle, pitch angle, and yaw angle. This allows the lightning rod unit 33 to be pointed directly vertically upward (returning to a non-tilted state) even when the unmanned aerial vehicle 20 is flying at an angle.

[0035] For example, when the roll angle is +30°, the control unit 34 calculates the rotation angle θ2 of the second stepping motor 32 as −30°, and rotates the second rotation shaft 321 of the second stepping motor 32 by −30°. When the yaw angle is +30°, the control unit 34 calculates the rotation angle θ1 of the first stepping motor 31 as −30°, and rotates the first rotation shaft 311 of the first stepping motor 31 by −30°.

[0036] When the pitch angle is +30°, the control unit 34 calculates +90° as the rotation angle θ1 of the first stepping motor 31 and -30° as the rotation angle θ2 of the second stepping motor 32. The control unit 34 then rotates the first rotation shaft 311 of the first stepping motor 31 by +90° and then rotates the second rotation shaft 321 of the second stepping motor 32 by -30°. In this embodiment, the first stepping motor 31 and the second stepping motor 32 each rotate about a single rotation shaft 311, 321. Therefore, to cancel out the tilt of the pitch angle, the control unit 34 rotates the first stepping motor by 90° and then rotates the second stepping motor so as to cancel out the tilt of the pitch angle.

[0037] When there are tilts at multiple angles, namely, the roll angle, the pitch angle, and the yaw angle, as described above, the first stepping motor 31 and / or the second stepping motor 32 are sequentially rotated by angles that cancel out each of the angles. For example, when the roll angle is +30° and the yaw angle is +30°, the control unit 34 calculates the rotation angle θ2 of the second stepping motor 32 as −30° and rotates the second rotation shaft 321 of the second stepping motor 32 by −30°, and further calculates the rotation angle θ1 of the first stepping motor 31 as −30° and rotates the first rotation shaft 311 of the first stepping motor 31 by −30°.

[0038] In this embodiment, the first stepping motor 31 is installed in the cage 10 that surrounds the unmanned aerial vehicle 20. For example, the first stepping motor 31 may be fixed to the top of the cage 10, as shown in FIG. 1 . The second stepping motor 32 is connected to a first rotation shaft 311 of the first stepping motor 31. The rotation angles of the first stepping motor 31 and the second stepping motor 32 are controlled in accordance with the flight attitude of the unmanned aerial vehicle 20, thereby tilting the lightning rod portion 33 at any angle relative to the unmanned aerial vehicle 20 (cage 10). This allows the lightning rod portion 33 to always be facing directly vertically upward.

[0039] 4A shows the unmanned aerial vehicle 20 flying while maintaining a horizontal attitude. In this case, the unmanned aerial vehicle 20 is not tilted, so the roll angle, pitch angle, and yaw angle output from the flight controller 21 to the control unit 34 are all 0°. The control unit 34 does not need to control the first stepping motor 31 and the second stepping motor 32, and the lightning rod unit 33 faces directly upward. When the lightning rod unit 33 faces directly upward, the entire cage 10 is within the protection range of the lightning rod unit 33. Therefore, when lightning strikes, it always strikes the lightning rod unit 33, significantly reducing the risk of lightning striking the cage 10 frame directly.

[0040] 4B shows a case where unmanned aerial vehicle 20 and cage 10 are flying in a tilted state due to strong winds or the like. Because the rotation angles of first stepping motor 31 and second stepping motor 32 are controlled according to the flight attitude of unmanned aerial vehicle 20, lightning rod portion 33 always faces straight up vertically, even if unmanned aerial vehicle 20 and cage 10 are tilted. As a result, the entire cage 10 is within the protection range of lightning rod portion 33, so if lightning strikes, it will always strike lightning rod portion 33 and will not strike directly on the frame of cage 10.

[0041] The lightning rod 30 for an unmanned aerial vehicle of this embodiment described above comprises a lightning rod section 33, a first stepping motor 31, and a second stepping motor 32 connected to a first rotation axis 311 of the first stepping motor 31 and rotating on a second rotation axis 321 that intersects with the first rotation axis 311, and the lightning rod section 33 is installed on the second rotation axis 321, and the rotation angles of the first stepping motor 31 and the second stepping motor 32 are controlled according to the flight attitude of the unmanned aerial vehicle 20.

[0042] In this embodiment, even if the unmanned aerial vehicle 20 and the cage 10 tilt, the lightning rod portion 33 of the lightning rod 30 always faces vertically upward. This significantly reduces the risk that a part of the cage 10 will go outside the protection range of the lightning rod 30, causing lightning to strike the frame of the cage 10 directly instead of the lightning rod 30.

[0043] That is, as shown in Figure 5A, even if the unmanned aerial vehicle 20 and the cage 10 are tilted, the lightning rod portion 33 of the lightning rod 30 is facing straight up vertically, so the entire cage 10 is within the protection range of the lightning rod 30, and if lightning strikes, it will generally strike the lightning rod 30, and it is unlikely that it will strike directly on the frame of the cage 10.

[0044] On the other hand, if the lightning rod 40 is fixed to the cage, as in the comparative example shown in Figure 5B, tilting the UAV and cage will also tilt the lightning rod 40. This will cause part of the cage to leave the protection range of the lightning rod 40, increasing the risk of lightning striking the cage directly rather than the lightning rod 40. If lightning strikes the cage directly, the large lightning current will flow into the cage frame without being diverted, which could damage the cage frame. Furthermore, the effect of canceling out the magnetic field within the cage will be reduced.

[0045] In this embodiment, two stepping motors 31, 32 are used to change the angle at which the lightning rod section 33 faces relative to the unmanned aerial vehicle 20 (cage 10), so that even if the unmanned aerial vehicle 20 is tilted, the lightning rod section 33 always faces straight up vertically. This significantly reduces the risk of lightning striking the frame of the cage 10, prevents damage to the cage 10, and increases the lightning resistance of the unmanned aerial vehicle 20.

[0046] The control unit 34 described above can be, for example, a general-purpose computer system as shown in Fig. 6. The computer system shown in the figure includes a CPU (Central Processing Unit, processor) 901, a memory 902, a storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), a communication device 904, an input device 905, and an output device 906. The memory 902 and the storage 903 are storage devices. In this computer system, the CPU 901 executes a predetermined program loaded on the memory 902, thereby realizing each function of the control unit 34.

[0047] The control unit 34 may be implemented in one computer or in multiple computers. The program for the control unit 34 may be stored in a computer-readable recording medium such as a HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), or DVD (Digital Versatile Disc), or may be distributed via a network. The computer-readable recording medium may be, for example, a non-transitory recording medium.

[0048] The present disclosure is not limited to the above-described embodiment and modified examples, and various modifications are possible within the scope of the gist thereof.

[0049] 10: Cage (Faraday cage) 20: Unmanned aerial vehicle (drone) 21: Flight controller 22: Sensor 23: Attitude control unit 30: Lightning rod 31: First stepping motor 32: Second stepping motor 33: Lightning rod unit 34: Control unit 39: Mounting bracket

Claims

1. A lightning rod for an unmanned aerial vehicle comprising: a lightning rod section; a first stepping motor; and a second stepping motor connected to a first rotation shaft of the first stepping motor and rotating on a second rotation shaft intersecting the first rotation shaft, wherein the lightning rod section is installed on the second rotation shaft, and the rotation angles of the first stepping motor and the second stepping motor are controlled according to the flight attitude of the unmanned aerial vehicle.

2. A lightning rod for an unmanned aerial vehicle as described in claim 1, further comprising a control unit that controls the first stepping motor and the second stepping motor, the control unit calculating the angles at which the first stepping motor and the second stepping motor are rotated, respectively, based on the pitch angle, yaw angle, and roll angle that indicate the flight attitude.

3. The lightning rod for an unmanned aerial vehicle according to claim 1, wherein the first stepping motor is installed in a cage surrounding the unmanned aerial vehicle.

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