Landmine detection system and landmine detection method

Abstract

To provide a mine detection system and a mine detection method that can efficiently search for mines placed on the ground while reducing the risk of injury to a searcher, and that can easily change the detection position to perform the search. [Solution] The mine detection system 1 includes, for example, a first drone device 2, which is equipped with an X-ray irradiation device 8 that irradiates X-rays, a second drone device 4, which is equipped with an X-ray detection device 22 that detects X-rays, and a control unit 30, wherein the control unit 30 has a detection mode 36 that detects backscattering of X-rays irradiated from the X-ray irradiation device of the first drone device using the X-ray detection device of the second drone device.

Description

[Technical Field]

[0001] The present invention relates to a land mine detection system and a land mine detection method. [Background technology]

[0002] As disclosed in Patent Document 1, a technique for detecting landmines is known in the past, which uses an infrared camera to capture images of the landmine and utilizes the difference in specific heat between the landmine and the area around it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-155460 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology shown in Patent Document 1 has the disadvantage of low measurement accuracy when landmines are hidden in the ground. Also, in order to detect landmines using this technology, measurements must be taken after a large change in temperature, when differences in specific heat can be utilized, which limits the efficiency of landmine detection.

[0005] The present invention has been made to solve these problems, and aims to provide a mine detection system and a mine detection method that can efficiently search for mines placed on the ground while reducing the risk of injury to the searcher, and that makes it easy to change the detection position and search. [Means for solving the problem]

[0006] In order to achieve the above object, according to one embodiment of the present invention, a mine detection system for detecting mines comprises: a first drone device, the first drone device having an X-ray irradiation device that irradiates X-rays; a second drone device, the second drone device having an X-ray detection device that detects X-rays; and a control unit, wherein the control unit has a detection mode in which backscattering of X-rays irradiated from the X-ray irradiation device of the first drone device is detected by the X-ray detection device of the second drone device. According to one embodiment of the present invention configured as described above, backscattered X-rays irradiated from the X-ray irradiator provided on the first drone can be detected by the X-ray detection device provided on the second drone. As a result, since the X-ray irradiator is mounted on the first drone and the X-ray detection device is mounted on the second drone, the X-ray irradiator and other devices can be moved safely in a minefield, reducing the risk of injury to the explorer, allowing for efficient exploration of mines placed on the ground and facilitating repeated exploration attempts by changing the search location. Furthermore, mine exploration can be carried out efficiently even at night or on cloudy days.

[0007] According to one embodiment of the present invention, the method for detecting landmines preferably includes an irradiation step of irradiating the ground with X-rays from an X-ray irradiation device provided in a first drone device, and a detection step of detecting backscattering of the X-rays irradiated in the irradiation step by an X-ray detection device provided in a second drone device. According to one embodiment of the present invention configured as described above, backscattered X-rays emitted from the X-ray irradiation device provided on the first drone device can be detected by the X-ray detection device provided on the second drone device. This allows the X-ray irradiation device and other devices to be moved safely in a minefield, reducing the risk of injury to the searcher, enabling efficient search for mines placed on the ground, and facilitating repeated searches at different search locations. Furthermore, mine search can be carried out efficiently even at night or on cloudy days. [Effects of the Invention]

[0008] The mine detection system and mine detection method of the present invention enable efficient detection of mines placed on the ground while reducing the risk of injury to the explorer, and also makes it easier to change the detection position for the search. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an overview of a first drone device, a second drone device, and a control unit of a mine detection system according to an embodiment of the present invention. FIG. [Figure 2] 1 is a schematic configuration diagram of a land mine detection system according to an embodiment of the present invention. [Figure 3] FIG. 2 is a block diagram showing the configuration of a first drone device in the mine detection system according to one embodiment of the present invention. [Figure 4] FIG. 2 is a block diagram showing the configuration of a second drone device in a mine detection system according to one embodiment of the present invention. [Figure 5] 2 is a block diagram showing the configuration of a control unit in the landmine detection system according to one embodiment of the present invention. FIG. [Figure 6] 2 shows a flowchart of a mine detection method for a mine detection system according to one embodiment of the present invention; [Figure 7] 1 is a diagram showing a first drone device and a second drone device in a mine detection system according to an embodiment of the present invention, moving sequentially through search points. FIG. [Figure 8] 1 is a side view showing a first drone device and a second drone device of a mine detection system according to an embodiment of the present invention detecting a mine at a search point. FIG. [Figure 9] 1 is a top view showing a first drone device and a second drone device of a mine detection system according to an embodiment of the present invention detecting mines at a search point. FIG. [Figure 10] 1 is a top view of a first drone device and a second drone device of a mine detection system according to an embodiment of the present invention, seen from above, in different positions at a search point. FIG. [Figure 11] FIG. 10 is a top view of the second drone device of the mine detection system according to one embodiment of the present invention, seen from above, moving at a search point and detecting X-rays. [Figure 12] FIG. 10 is a top view of a modified example of a mine detection system according to an embodiment of the present invention, in which there is one second drone device, showing the drone moving around a search point and detecting X-rays. [Figure 13] This is a top view of a modified example of a mine detection system according to an embodiment of the present invention, in which there are multiple second drone devices, in a deployed configuration at a search point. [Figure 14] 1 is a side view of a first drone device of a mine detection system according to an embodiment of the present invention, seen from the side, landing at a search point and emitting X-rays. DETAILED DESCRIPTION OF THE INVENTION

[0010] A mine detection system 1 according to an embodiment of the present invention will now be described with reference to the accompanying drawings. The embodiments of the present disclosure have been described as examples, and it will be apparent to those skilled in the art that many variations, modifications, and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention is not limited to the disclosed embodiments, and various variations, modifications, etc. can be made in form and details without departing from the scope of the claims. Furthermore, the components disclosed in the specification can be freely combined.

[0011] 1, a mine detection system 1 according to an embodiment of the present invention can detect mines. The mine detection system 1 includes a first drone device 2 and a second drone device 4. In the following description of one embodiment of the present invention, as shown in FIG. 5, the sky side of the first drone device of the landmine detection system 1 is referred to as the upper side, and the ground side of the first drone device is referred to as the lower side. Landmines M are present on the surface of the ground G or buried underground near the surface. Landmines M are often present, for example, at a depth of 1 to 10 cm below the surface, or, for example, at a depth of 1 to 5 cm below the surface. There are various types of landmines M, including those in which explosives are placed inside a metal container and those in which explosives are placed inside a plastic or other resin container that cannot be detected by metal detectors. Anti-personnel landmines M are sized to have a diameter of 5 to 20 cm, while anti-tank landmines can be as large as a manhole cover. To minimize human casualties, it is important to safely search for, detect, and dispose of landmines M.

[0012] The first drone device 2 includes a first drone 6, an X-ray irradiation device 8 that irradiates X-rays, a first drone side camera 10 (see Figure 3), a first drone side altitude measurement device 12 (see Figure 3), a first drone side GPS device 14 (see Figure 3), a first drone side communication unit 15, and a first drone side control unit 16.

[0013] The first drone 6 is an unmanned aerial vehicle, such as a multicopter drone, but may be another type of unmanned aerial vehicle. The first drone 6 comprises a main body 6a and four arms extending from the main body 6a. Each arm has a rotor 6b and blades (rotating wings) 6c for rotating the blades. The first drone 6 is configured to move forward, backward, left, right, and up and down by controlling the rotation speed of each blade 6c. The first drone 6 is configured to generate lift sufficient to fly an X-ray irradiation device 8 mounted thereon. In this embodiment, the first drone 6 comprises four arms and one blade attached to each arm (a total of four blades). However, other numbers of arms and blades attached to each arm may be used. The first drone 6 can fly to a predetermined location, altitude, and course, and take off and land automatically according to a predetermined program, controlled by a control unit 30 (described later). Therefore, the first drone 6 can search for mines along a predetermined route from a starting point A (see FIG. 7) and return to a return point, such as the same point as the starting point. The first drone device 2 may be provided with a manual operation unit (not shown) and all or part of the control may be manually operated by the manual operation unit. The first drone 6 may be changed to another type of flying object that can fly anywhere, such as a helicopter.

[0014] As shown in FIG. 1, the X-ray irradiator 8 irradiates X-rays 50. The X-ray irradiator 8 has a structure that generates X-rays from an X-ray tube. The X-ray irradiator 8 is configured to obtain strong X-ray penetration and high-contrast images by increasing or decreasing the tube voltage and tube current. X-rays are electromagnetic waves with wavelengths ranging from 0.01 nm to 10 nm, for example. The X-ray irradiator 8 can irradiate the ground with an X-ray beam that has a diameter of approximately 10 cm when it reaches the ground G from an altitude of 100 cm during hovering. The X-ray irradiator 8 can irradiate the ground with an X-ray beam that has a diameter of approximately 5 cm when it reaches the ground G from an altitude of 50 cm during hovering. The X-ray irradiator 8 can irradiate the ground with an X-ray beam that has a diameter of approximately 3 cm when it reaches the ground G from an altitude of 30 cm during hovering. By reducing the X-ray beam diameter (spot diameter) when it reaches the ground G, the detection accuracy of backscatter 52 can be improved. The X-ray beam diameter can be adjusted by the mechanism of the X-ray irradiator 8. For example, the diameter of the X-ray spot irradiated on the ground G can be, for example, within a range of 2 cm to 30 cm, for example, within a range of 2 cm to 10 cm. The X-ray irradiator 8 is sized and weighed to be mountable on the first drone 6. The X-ray tube of the X-ray irradiator 8 can weigh, for example, within a range of 300 g to 2000 g. Furthermore, the control circuit of the X-ray irradiator 8 can weigh, for example, within a range of 1000 g to 2500 g. To further increase the X-ray output and improve the detection accuracy of backscatter 52, the size of the X-ray tube may be increased within a predetermined range. Because this technology operates on a minefield, the possibility of people being present nearby is extremely low. This allows for the reduction or elimination of protective equipment to prevent X-ray leakage on the first drone device 2. The increased weight allows for a larger X-ray tube to be installed, improving the detection accuracy of backscatter. The X-ray irradiation device 8 also includes a power supply device for the irradiation device that irradiates X-rays.

[0015] The first drone camera 10 is mounted on the main body 6a of the first drone 6, and allows the first drone 6 to photograph and see the surrounding situation. The first drone camera 10 has the ability to take videos and photos. The first drone camera 10 allows the user to check the situation around the first drone camera 10 from a remote location, and also photograph and record the situation of the ground at the search point (detection point). The first drone camera 10 is mounted so that it can also photograph the situation directly below the first drone 6 in order to check the situation vertically below where the X-rays are emitted.

[0016] The first drone altitude measurement device 12 is provided on the airframe main body 6a and can measure the altitude H (distance) of the first drone 6 relative to the ground G, where there may be buried mines M. The first drone altitude measurement device 12 uses, for example, an ultrasonic altimeter that can measure the height to the ground G. The first drone altitude measurement device 12 may be configured with any one of a barometric pressure measurement sensor that can measure flight altitude by measuring air pressure, an ultrasonic sonar that can measure the distance from the first drone 6 to the ground G, a laser measurement sensor that can measure the distance from the first drone 6 to the ground G, a LIDAR sensor that can measure the distance from the first drone 6 to the ground G, or any combination of these. This allows the first drone altitude measurement device 12 to measure the altitude H (distance) from the first drone 6 to the ground G. For example, the first drone altitude measurement device 12 can measure an altitude (distance) H (e.g., H0, described later) within a predetermined distance range of 10 cm to 2 m from the first drone 6 to the ground G, more preferably an altitude H within a range of 30 cm to 1 m, and more preferably an altitude H within a range of 30 cm to 50 cm. The first drone altitude measurement device 12 can also measure and recognize the state in which the first drone 6 is in contact with the ground G. After the first drone altitude measurement device 12 recognizes the altitude H (distance) to the ground G, it can, for example, control the X-ray irradiation device 8 to irradiate X-rays in response to a command from the control unit 30.

[0017] The first drone's GPS device 14 is capable of using satellites to identify the current position of the first drone 6. The first drone's GPS device 14 can acquire position information (such as latitude and longitude information) of the point where the X-ray irradiation device 8 irradiates and detects X-rays. Furthermore, the first drone's GPS device 14 can recognize the position of the first drone 6 and provide the position information necessary for predetermined flight control of the first drone 6.

[0018] The first drone communication unit 15 can wirelessly communicate data from the first drone device 2 with the second drone communication unit 27 of the second drone device 4 and the control unit 30. For example, the first drone communication unit 15 can transmit information such as the position (coordinates, altitude) of the first drone 6 and the position of X-ray irradiation by the X-ray irradiation device 8 to the second drone communication unit 27. The first drone communication unit 15 can also share position information and control information with the second drone communication unit 27. The control unit 30 enables group control of the first drone device 2 and the second drone device 4, and can acquire the position of the first drone device 2 and the detected position and detection information of the second drone device 4 by linking them together.

[0019] The first drone device 2 may be equipped with a manual operation unit, a monitor, etc. as needed.

[0020] The first drone control unit 16 has a built-in CPU 17 and a storage device 19 such as memory, and controls connected devices to execute predetermined controls based on predetermined control programs stored in the memory, etc. The first drone control unit 16 is electrically connected to the first drone 6, X-ray irradiation device 8, first drone camera 10, first drone altitude measurement device 12, first drone GPS device 14, first drone communication unit 15, etc. These electrical connections may be made via wireless communication, etc.

[0021] The first drone control unit 16 can execute flight control of the first drone 6. The first drone control unit 16 is configured to perform predetermined functions in cooperation with the control unit. The first drone control unit 16, together with the control unit, controls the first drone device 2 and the flight of the first drone 6. More specifically, the first drone control unit 16 can control the position (coordinates, altitude) at which the X-ray irradiator 8 irradiates X-rays, attitude control during irradiation, rotation suppression control in the yawing direction, movement between detection points, etc. In this way, the first drone control unit 16 can control the flight altitude, flight route, rotation speed of each blade, attitude (including left and right roll and yawing in the rotational direction), and operation control of the X-ray irradiator 8 as needed, etc. of the first drone 6. The first drone control unit 16 can control the first drone 6 to reach a predetermined altitude above the target point (search point) and the X-ray irradiator 8 to irradiate X-rays toward the ground G. The first drone control unit 16 may be provided integrally with the control unit 30. For example, all or part of the functions of the first drone-side control unit 16 may be provided on the control unit side, or all or part of the functions of the first drone-side control unit 16 may be provided in an information terminal device or the like on the operation unit (not shown) side.

[0022] The first drone device 2 may include a tank 11 containing a coloring liquid and a coloring unit 13 that drops the coloring liquid from the tank 11. This allows a location where a mine may be detected to be marked on the ground, which is useful for later mine clearance. In this case, when the control unit 30 determines that a predetermined object has been detected using the mark mode 44, the control unit drops the coloring liquid from the tank to leave a mark on the ground.

[0023] The second drone device 4 includes a second drone 20, an X-ray detection device 22 that detects X-rays, a second drone side camera 24, a second drone side altitude measurement device 25, a second drone side GPS device 26, a second drone side communication unit 27, and a second drone side control unit 28.

[0024] The second drone 20 is an unmanned aerial vehicle, such as a multicopter drone, but may be another type of unmanned aerial vehicle. The second drone 20 includes a main body 20a and four arms extending from the main body 20a. Each arm has a rotor 20b for rotating the blades and a blade (rotor) 20c. By controlling the rotation speed of each blade 20c, the second drone 20 can move forward, backward, left, right, and up and down. The second drone 20 is configured to generate lift sufficient to fly an X-ray detection device 22 mounted thereon. In this embodiment, the second drone 20 includes four arms and one blade attached to each arm (a total of four blades), but other numbers of arms and blades attached to each arm may be used. The second drone 20 can fly to a predetermined location, at a predetermined altitude, and along a predetermined course, and can also take off and land fully automatically according to a predetermined program, controlled by a control unit 30 (described later). Therefore, the second drone 20 can search for mines along a predetermined route from the starting point A (see FIG. 7) and return to a return point, for example, the same point as the starting point. The second drone device 4 may be equipped with a manual operation unit (not shown), and all or part of the control may be manually operated by the manual operation unit. The second drone 20 may also be changed to another type of flying object that can fly anywhere, such as a helicopter.

[0025] The X-ray detection device 22 is a device capable of detecting X-rays and visualizing and imaging the attenuation of X-rays. The X-ray detection device 22 converts the received X-rays into visible light (scintillation light) using a fluorescent material called a scintillator, and then converts the light into an electrical signal using a detector such as an image sensor to obtain image information. The X-ray detection device 22 includes, for example, a flat panel sensor (flat panel detector) in which pixels are arranged in a two-dimensional (planar) direction. The X-ray detection device 22 may also convert X-rays into digital signals using, for example, a line sensor in which image elements are arranged only in a one-dimensional direction, enabling digital imaging. Generally, scintillators measuring 6 inches (15.24 cm) in length and width or 8 inches (20.32 cm) in length and width are relatively easy to obtain. Increasing the number of second drone devices 4 can achieve the same effect as increasing the size of the scintillator.

[0026] The second drone camera 24 can photograph and view the surrounding situation from the second drone 20. The second drone camera 24 has the ability to take videos and photos. The second drone camera 24 allows the user to check the situation around the second drone camera 24 from a remote location, and can also photograph and record the situation of the ground at the detection point below the second drone camera. The second drone camera 24 is installed so that it can also photograph the situation directly below the second drone 20 in order to check the situation vertically below where the X-rays are emitted.

[0027] The second drone altitude measurement device 25 can measure the altitude H (distance) of the second drone 20 relative to the ground G, where there may be buried mines M. The second drone altitude measurement device 25 uses, for example, an ultrasonic altimeter that can measure the height to the ground G. The second drone altitude measurement device 25 may be configured with any one of a barometric pressure measurement sensor that can measure the flight altitude by measuring the air pressure, an ultrasonic sonar that can measure the distance from the second drone 20 to the ground G, a laser measurement sensor that can measure the distance from the second drone 20 to the ground G, a LIDAR sensor that can measure the distance from the second drone 20 to the ground G, or any combination of these. This allows the second drone altitude measurement device 25 to measure the altitude H (distance) from the second drone 20 to the ground G. For example, the second drone altitude measurement device 25 can measure an altitude (distance) H (e.g., H1, H2 described below) within a predetermined distance range of 10 cm to 2 m from the second drone 20 to the ground G, more preferably an altitude H within a range of 30 cm to 1 m, and more preferably an altitude H within a range of 30 cm to 50 cm. The second drone altitude measurement device 25 recognizes the altitude H (distance) to the ground G, and can, for example, control the second drone 20 to an altitude different from or the same as that of the first drone 6.

[0028] The second drone's GPS device 26 is capable of using satellites to identify the current position of the second drone 20. The second drone's GPS device 26 can acquire position information (such as latitude and longitude information) of the point where the X-ray detection device 22 detected X-rays. The second drone's GPS device 26 can recognize the position of the second drone 20 and provide the position information necessary for predetermined flight control of the second drone 20.

[0029] The second drone communication unit 27 can wirelessly communicate data from the second drone device 4 with the first drone communication unit 15 of the first drone device 2 and the control unit 30. For example, the second drone communication unit 27 can transmit information such as the position (coordinates, altitude) of the second drone 20 and the position of X-rays detected by the X-ray detection device 22 to the first drone communication unit 15. The second drone communication unit 27 can also mutually share position information and control information with the first drone communication unit 15. The control unit 30 enables group control of the first drone device 2 and the second drone device 4, and can acquire the position of the first drone device 2 and the detected position and detection information of the second drone device 4 by linking them together.

[0030] The second drone device 4 may be equipped with a manual operation unit, a monitor, etc. as necessary. The second drone device 4 may also be equipped with an earthing metal wire 23 that extends from the body of the second drone device 4 to the ground at the altitude where detection is performed by the X-ray detection device 22. This reduces the effect of static electricity caused by the rotation of the blades of the second drone device 4 on X-ray detection, improving the accuracy of mine detection.

[0031] The second drone control unit 28 has a built-in CPU 29 and a storage device 31 such as memory, and controls connected devices to execute predetermined controls based on predetermined control programs stored in the memory, etc. The second drone control unit 28 is electrically connected to the second drone 20, X-ray detection device 22, second drone camera 24, second drone altitude measurement device 25, second drone GPS device 26, second drone communication unit 27, etc. These electrical connections may be made via wireless communication, etc.

[0032] The second drone-side control unit 28 can execute flight control of the second drone 20. The second drone-side control unit 28 is configured to perform predetermined functions in cooperation with the control unit 30. The second drone-side control unit 28, together with the control unit, controls the second drone device 4 and the flight of the second drone 20. More specifically, the second drone-side control unit 28 can control the position (coordinates, altitude) where the X-ray detection device 22 detects X-rays, attitude control during irradiation, rotation suppression control in the yawing direction, movement between detection points, etc. In this way, the second drone-side control unit 28 can control the flight altitude, flight route, rotation speed of each blade, attitude (including left and right roll and yawing in the rotational direction), and operation control of the X-ray detection device 22 as needed, etc. The second drone-side control unit 28 can control the second drone 20 to arrive at a predetermined altitude above the target point (search point) and the X-ray detection device 22 to detect X-rays. Furthermore, the second drone-side control unit 28 can recognize the positional relationship between the second drone 20 and the first drone 6 and execute predetermined control to position the second drone 20 at a predetermined position relative to the first drone 6. The second drone-side control unit 28 may be provided integrally with the control unit. For example, all or part of the functions of the second drone-side control unit 28 may be provided on the control unit side. All or part of the functions of the second drone-side control unit 28 may be provided in an information terminal device or the like on the operation unit (not shown) side.

[0033] The mine detection system 1 further includes a control unit 30. The control unit 30 is configured to control the detection of backscattered X-rays 52 emitted from the X-ray irradiation device 8 of the first drone device 2 by the X-ray detection device 22 of the second drone device 4. The control unit 30 is provided, for example, in a computer located remotely from the first drone device 2, the second drone device 4, etc. The control unit 30 is electrically connected to the first drone device 2, the second drone device 4, etc. via the Internet 3. The control unit 30 may also be provided in an electronic device that functions as a computer, such as a smartphone or tablet. The control unit 30 incorporates a CPU 33 and a storage device 35 such as a memory, and controls connected devices based on a predetermined control program recorded in the memory, etc. Thus, the control unit 30 functions as a computer. The control unit 30 may be electrically connected to other devices, in whole or in part, via wireless communication such as infrared communication or other methods. The control unit 30 has a predetermined program for executing a predetermined control function. The control unit 30 may also be composed of multiple devices. The storage device 35 of the control unit 30 stores a predetermined program, but does not necessarily need to store all of the programs; some or all of the programs may be stored separately on multiple devices, or may be stored on a server via the Internet. For example, the first drone control unit 16 or the second drone control unit 28 mounted on the first drone device 2 or the second drone device 4 may be configured to execute some or all of the control functions. The control unit 30 is equipped with an output device 32 such as a monitor and an input device 34 that can be operated to input, and is capable of setting various modes, etc.

[0034] Backscatter 52 (backscattered X-rays) are scattered rays (scattered X-rays) generated from an object when the object is irradiated with X-rays 50. In principle, the X-ray detection device 22 measures the intensity of the scattered X-rays and generates an image by representing the intensity of the scattered X-rays with shades of gray. Backscattered X-rays spread hemispherically upward from the mine M. For example, the scattered X-rays are detected with improved accuracy using multiple second drone devices 4, thereby achieving both convenience of the measurement method and improved measurement accuracy.

[0035] The control unit 30 has a detection mode 36 in which backscattering of X-rays irradiated from the X-ray irradiation device 8 of the first drone device 2 is detected by the X-ray detection device of the second drone device 4. The control unit 30 has a pre-measurement mode 37 in which, before starting irradiation from the X-ray irradiation device 8, the X-ray values ​​of the natural environment at the search point are detected and recorded using the X-ray detection device of the second drone device. The control unit 30 has a low-altitude irradiation mode 38 that causes the X-ray irradiation device 8 to irradiate X-rays while the first drone device is hovering at a height ranging from 30 cm to 100 cm above the ground. The control unit 30 has a landing irradiation mode 39 that causes the X-ray irradiation device 8 to irradiate X-rays while the first drone device is landed on the ground. The control unit 30 has a first detection mode 40 that positions the second drone device above the first drone device when X-ray irradiation is performed by the X-ray irradiation device 8 of the first drone device. The control unit 30 has a deployment mode 41 in which X-ray detection is performed by the X-ray detection device while the second drone device is positioned at equal intervals on a circumference centered on the first drone device when viewed from above. The control unit 30 has an altitude difference mode 42 in which one of the second drone devices 4 performs detection using the X-ray detection device 22 at a first altitude H1, and one of the remaining second drone devices 4 performs detection using the X-ray detection device 22 at a second altitude H2 higher than the first altitude H1. The control unit 30 has a moving detection mode 43 in which, while the first drone device 2 is irradiating X-rays using the X-ray irradiation device 8, the second drone device 4 detects X-rays using the X-ray detection device at a first location, and the second drone device 4, which has detected X-rays at the first location, is moved to a second location and the second drone device 4 detects X-rays using the X-ray detection device at the second location. The device further includes a mark mode 44 in which, when the control unit 30 determines that a predetermined object has been detected, the control unit drops coloring liquid from the tank and leaves a mark on the ground. The control unit 30 has a course setting mode 45 that executes control to detect backscattered X-rays by the X-ray detection device of the second drone device at multiple points along a predetermined course.

[0036] Next, a series of operations for detecting a land mine by the land mine detection system 1 will be described as shown in FIG. As shown in FIG. 6, in preparation step S1 of the mine detection system 1, the first drone device 2, second drone device 4, control unit 30, etc. of the mine detection system 1 are prepared. The first drone device 2 and second drone device 4 are installed at starting point A (see FIG. 7). The X-ray irradiation device 8 and X-ray detection device 22 are also prepared so that they can be used. The control unit 30 also prepares or acquires flight data for the first drone device 2 and second drone device 4 (for example, coordinates of the search point (see FIG. 7), flight route, flight altitude data (detection altitude data) relative to the ground G at the search point coordinates, etc.). When step S1 is completed, the control unit 30 proceeds to S2.

[0037] In step S2, the control unit 30 flies the first drone 2 and the second drone 4 from the starting point A to above the search point D1 in the search area D. Search point D1 is the point where the mine detection process is performed. The control unit 30 stops the operation of the X-ray irradiation device 8 while the first drone 2 is moving. The control unit 30 stops the operation of the X-ray detection device 22 while the second drone 4 is moving.

[0038] The control unit 30 can automatically fly the first drone 2 and the second drone 4 along a predetermined course, such as the course indicated by arrow F, using a predetermined program. The control unit 30 can also use a course setting mode 45 to execute control to detect backscattered X-rays using the X-ray detection device of the second drone at multiple points along the predetermined course. This allows for automatic search for mines M at multiple points along the predetermined course. Arrow F illustrates an example of a predetermined course that thoroughly searches the search area D while turning back and forth. However, the course may be changed depending on the terrain, etc., as long as it can fully search the search area D. By searching at search points D1 to D16 along the predetermined course, screening for the presence of mines within the search area D can be performed, improving the accuracy of the screening process.

[0039] With the first drone device 2 proceeding to search point D1, the control unit 30 causes the first drone 6 to almost stop (hover) in the air above search point D1. At this time, the control unit 30 maintains the first drone 6 at a predetermined altitude H (H0), for example, an altitude of 30 cm above the ground G. When step S2 is completed, the control unit 30 proceeds to S3.

[0040] In step S3, in advance measurement mode 37 of control unit 30, before starting irradiation from X-ray irradiation device 8, the X-ray value of the natural environment at the search point is detected and recorded by the X-ray detection device of second drone device 4 with the first drone device 2 and second drone device 4 in the same position as at the time of irradiation. When first drone device 2 and second drone device 4 have arrived at search point D1, in advance measurement mode 37, before starting irradiation from X-ray irradiation device 8, control unit 30 detects and records the X-ray value of the natural environment at the detection point with the X-ray detection device on the second drone. This makes it possible to compare the X-ray value of the natural environment at the planned detection point with the value detected by the X-ray detection device of backscattered X-rays, reducing the influence of X-rays in the natural environment and improving the accuracy of mine detection.

[0041] In step S4, the control unit 30, in detection mode 36, detects backscattering of X-rays irradiated from the X-ray irradiator 8 of the first drone device 2 using the X-ray detection device of the second drone device 4. First, the control unit 30 activates the X-ray irradiator 8 at the search point D1 to irradiate an X-ray beam toward the ground G directly below. The X-ray irradiator 8 irradiates the ground G with an X-ray beam that has a diameter of approximately 3 cm when it reaches the ground G. The control unit 30 controls the first drone 2 and the second drone 4 so that they are in a predetermined positional relationship during X-ray irradiation and detection. The control unit 30 controls the first drone 2 and the second drone 4 as if they were a team (group). In low-altitude irradiation mode 38, the control unit 30 causes the X-ray irradiator 8 to irradiate X-rays while the first drone is hovering at a height between 30 cm and 100 cm above the ground. This allows X-rays to be irradiated from a low altitude (where the distance between the landmine and the first drone is relatively short) at which the effect of X-ray irradiation by the X-ray irradiator 8 is relatively high, thereby improving the accuracy of landmine detection.

[0042] If a mine M is present on the ground G, the X-ray beam will strike the mine M, causing backscattering of the X-rays. The backscattered X-rays will spread upward in a hemispherical shape from the mine M. The X-ray detection device 22 detects the backscattered X-rays.

[0043] The communication unit of each second drone device 4 transmits the measurement data of the X-rays detected by the X-ray detection device 22 to the control unit 30. The control unit 30 compares the X-ray measurement data acquired before X-ray irradiation with the X-ray measurement data acquired during X-ray irradiation for each second drone device 4 for the search point D1, and measures and calculates backscattered X-rays. If a mine M is present at the search point D1, backscattered X-rays are measured and calculated at a predetermined level. For example, even if the X-ray beam is only focused on about half of the mine M, backscattered X-rays of a certain intensity can be measured, indicating the presence of the mine M. Even if a different object is buried, backscattered X-rays may be measured and calculated at a predetermined level. For example, if an empty can is found buried, it can be confirmed on-site. Simply knowing the presence or absence of an object reduces the workload of the mine disposal unit, providing a certain effect. Furthermore, even if a different object is buried, if it is a relatively large object such as an iron pipe or iron plate, it will be detected at the next search point D2, D3, etc., and it can be determined that there is a high possibility that an object other than mine M has been buried there.Although this also requires on-site confirmation, simply knowing in advance whether or not an object is present and its nature reduces the workload of the mine disposal unit, and has a certain effect.

[0044] In step S4, when the control unit 30 completes the process of irradiating X-rays by the first drone device 2 and detecting X-rays by the second drone device 4 for the search point D1, the control unit 30 proceeds to S5.

[0045] In step S5, the control unit 30 determines whether detection has been completed at all of the planned search points, and if detection has not been completed at all of the planned search points (NO), the process returns to S2. In step S5, if the control unit 30 determines whether detection has been completed at all planned search points (YES), the control unit 30 proceeds to S6.

[0046] When returning to S2, the control unit 30 moves the first drone device 2 and the second drone device 4 to the next search point D2, and thereafter executes the processes of S3 and S4. When the process of X-ray irradiation by the first drone device 2 and X-ray detection by the second drone device 4 at the search point D2 is completed, the process proceeds to S5 again, and the determination process of S5 is executed. After searching for search point D2, the control unit 30 proceeds from S5 to S2 and similarly executes the processes of S2, S3, and S4 at search point D3. Search area D is indicated by a virtual dashed line in FIG. 7 . The control unit 30 controls the first drone 2 and the second drone 4 to travel to mine search points D1, D2, D3, D15, and D16, and controls the X-ray irradiator 8 to irradiate and detect X-rays at each point. For example, the distance K between search point D1 and search point D2 is set to a value ranging from approximately 15 cm to approximately 100 cm, such as a value ranging from approximately 15 cm to approximately 50 cm, or approximately 30 cm. The distance K may be set to approximately two or three times the outer width of the mine M to be searched for. For example, if the outer width (outer diameter) of the mine M is approximately 10 cm, the distance K may be set to 20 cm. The distance between search points D1 and D8 (similarly, the distance between search points D2 and D7) is also set to distance K. Note that the distance between search points D1 and D8 may be set to a value different from distance K. A search area D searched at such distances is, for example, a 5 m square area, a 3 m square area, etc. The search area D can also be applied to areas with sides each having a length within the range of 1 m to 20 m. The search area D is a virtual area, and its shape and size can be set by setting a course, etc. When the control unit 30 completes the processes of S2, S3, and S4 at the search point D16, the process proceeds to S6.

[0047] In step S6, the control unit 30 executes a return flight step, returning the first drone 2 and the second drone 4 from search point D16 to the starting point A. In this way, the control unit 30 can, for example, fully automatically cause the first drone 2 and the second drone 4 to depart from the starting point A, perform a series of searches for mines within the search area D, and return them to the starting point A. If the control unit 30 could fully automatically collect information on mines within the search area D, it would reduce the manual search effort of workers and improve worker safety. Furthermore, the mine detection system 1 can cause the first drone 2 and the second drone 4 to perform searches and detections, day or night, and the mine detection system 1 can continue to search for mines, which contributes to facilitating and streamlining removal work.

[0048] Next, the improvement of mine detection performance by team formation and deployment configurations based on combinations of the first drone device 2 and the second drone device 4 will be described. By performing the above steps in a predetermined team formation and deployment form, it is possible to further improve detection accuracy and measurement efficiency.

[0049] A plurality of second drone devices 4 equipped with X-ray detection devices 22 are provided for each first drone device 2. For example, two or more second drone devices 4 form a team. For example, two to nine second drone devices 4 may be provided to form a team. Although efficiency is somewhat reduced, even a single second drone device 4 can provide a certain level of effectiveness. For example, if there are two or more second drone devices 4, there is an advantageous effect that the detection area of ​​the X-ray detection device 22 can be widened, and there is an advantageous effect that measurement results at multiple locations can be obtained in a short time compared to when measuring at multiple locations with one second drone device 4. In addition, since measurements are performed using multiple devices, the reliability of the measurement results can be improved.

[0050] As shown in FIG. 8 , when multiple second drone devices 4 are provided, the control unit 30 can position the second drone device 4 higher than the first drone device when X-ray irradiation is performed by the X-ray irradiation device 8 of the first drone device in the first detection mode 40. This makes it difficult to detect X-ray leakage from the X-ray irradiation device 8, improving the accuracy of X-ray detection by the X-ray detection device of the second drone device 4. This further improves the accuracy of mine detection. For example, when four second drone devices 4 are provided, two of the four second drone devices 4 detect X-rays using the X-ray detection device 22 at a predetermined altitude H1 higher than the predetermined altitude H0 of the first drone device 2. The remaining two second drone devices 4 are located at a predetermined altitude H2 higher than the predetermined altitude H1 and can detect X-rays using their respective X-ray detection devices 22. For example, the predetermined altitude H2 can be approximately twice the predetermined altitude H1. The difference between the predetermined altitude H2 and the predetermined altitude H1 may be within a range of 30 cm to 100 cm. Furthermore, in altitude difference mode 42, control unit 30 controls one of second drone devices 4 to perform detection using X-ray detection device 22 at first altitude H1, and one of the remaining second drone devices 4 to perform detection using X-ray detection device 22 at second altitude H2 higher than first altitude H1. This allows detection using the X-ray detection device at first altitude H1 and detection using the X-ray detection device at second altitude H2 to be performed in parallel, further improving the accuracy of mine detection.

[0051] As shown in Figures 9 and 10, the control unit 30, in deployment mode 41, performs X-ray detection using the X-ray detection device 22 while the second drones 4 are positioned at equal intervals circumferentially on a circle centered on the first drone 2 in a top view. This allows the detection area of ​​the X-ray detection device 22 to be wider than when there is only one second drone 4, thereby improving mine detection accuracy with a short irradiation time. The positions of the two second drones 4 flying at a predetermined altitude H1 are symmetrical on a circle of the same radius centered on the first drone 2, which is directly above search point D1 in a top view. The positions of the two second drones 4 flying at a predetermined altitude H2 are symmetrical on a circle of the same radius centered on the first drone 2, which is directly above search point D1 in a top view. As shown in Figure 9, for example, when viewed from above, a second drone device 4 (H1) at a predetermined altitude H1 and a second drone device 4 (H2) at a predetermined altitude H2 are arranged in a linearly aligned deployed form.

[0052] As a variant, as shown in FIG. 10, the second drones 4 (H1) at a predetermined altitude H1 and the second drones 4 (H2) at a predetermined altitude H2 may be deployed in a cross-shaped configuration in a top view. The altitudes of the second drones 4 (H1) and 4 (H2) are varied in steps. This shortens the distance between the second drones 4 (H2) and the mines M that are the source of backscatter compared to when they are arranged in a straight line, improving measurement accuracy. In this case, too, the deployment mode 41 positions the second drones 4 at equal intervals around the first drone 2 in a top view.

[0053] 11, the second drone device 4 can change its detection position, for example, by sliding it horizontally to increase the number of search points (measurement points), thereby increasing the number of measurement points. In the moving detection mode 43, while the first drone device 2 is irradiating X-rays with the X-ray irradiation device 8, the control unit 30 causes the X-ray detection device of the second drone device 4 to detect X-rays at a first point (a point where the drone is indicated by a solid line in FIG. 11, which will be described later), and moves the second drone device 4, which has detected X-rays at the first point, to a second point (a point where the drone is indicated by a dashed line in FIG. 11, which will be described later), and causes the X-ray detection device of the second drone device 4 to detect X-rays at the second point. By increasing the number of measurement points by the second drone device 4, the apparent detection area of ​​the X-ray detection device 22 increases, thereby improving the accuracy of mine detection. While the X-ray irradiation device 8 is irradiating X-rays, the X-ray detection device 22 can change its position and attempt to detect similar backscattered X-rays regardless of the time domain. Therefore, by increasing the number of measurement points by the second drone device 4 to two, a detection area similar to that obtained when measurement is performed using two second drone devices 4 can be obtained. For example, when measurement is performed using four second drone devices 4 as in this embodiment, the four second drone devices 4 can perform a first X-ray detection in the deployment arrangement shown in FIG. 9, and then a second X-ray detection can be performed in the deployment arrangement shown in FIG. 11.

[0054] As shown in FIG. 11 , for example, the second drone device 4 (H1) at a predetermined altitude H1 moves horizontally along arrow J to the position indicated by the dashed line while maintaining the predetermined altitude H1, and then performs a second X-ray detection. Similarly, the second drone device 4 (H2) at the predetermined altitude H1 moves horizontally along arrow J to the position indicated by the dashed line while maintaining the predetermined altitude H2, and then performs a second X-ray detection. The second drone device 4 (H1) moves 90 degrees around the first drone device 2 while maintaining the predetermined altitude H1, and the second drone device 4 (H2) moves 90 degrees around the first drone device 2 while maintaining the predetermined altitude H2. In this way, measurement results at eight locations can be obtained by the second drone device 4. Note that the movement angle and movement distance of the second drone device 4 may be changed in the same manner. Furthermore, the second drone device 4 may move so that the first measurement altitude and the second measurement altitude are different. Furthermore, the second drone device 4 may move three or more times to measure at multiple locations, not just twice, to improve the accuracy of the measurement results. Because the second drone device 4 moves through space, it is easy to change its position and deployment form.

[0055] 10, for example, in a top view where the second drone device 4 (H1) at a predetermined altitude H1 and the second drone device 4 (H2) at a predetermined altitude H2 are arranged in a cross shape, the second drone device 4 (H1) may be moved 90 degrees around the first drone device 2 while maintaining the predetermined altitude H1, and the second drone device 4 (H2) may be moved 90 degrees around the first drone device 2 while maintaining the predetermined altitude H2. In this way, measurement results at eight locations can be obtained by the second drone device 4.

[0056] As a variant, only one second drone device 4 equipped with an X-ray detection device 22 may be provided for each first drone device 2. When there is one second drone device 4, the measurement accuracy is lower than when there are multiple second drone devices 4, but mine detection processing can be performed with a simpler system configuration. In this case, in order to increase the number of measurement points and increase the apparent detection area of ​​the X-ray detection device 22, the second drone device 4 may change its detection position and perform X-ray detection multiple times. For example, the second drone device 4 (H1) at a predetermined altitude H1 moves horizontally along arrow J to the position indicated by the dashed line while maintaining the predetermined altitude H1, and then performs the second X-ray detection. Alternatively, the second drone device 4 may perform X-ray detection at multiple locations while orbiting the first drone device 2. In this way, the second drone device 4 can obtain measurement results from two or more locations.

[0057] As shown in FIG. 13, as a modified example, multiple second drone devices 4 equipped with X-ray detection devices 22, such as 11, may be operated simultaneously for one first drone device 2. The first drone device 2 is irradiated with X-rays by the X-ray irradiation device 8 when at a predetermined altitude H0. The second drone device 4 detects X-rays by the X-ray detection device 22 when at a predetermined altitude H1. Using multiple drone devices prevents complex movement of the second drone device 4, allowing the first drone device 2 and the second drone device 4 to move simply while maintaining their deployed formation. The placement and altitude setting of the second drone device 4 can be freely changed.

[0058] Examples of an embodiment of the present invention may be provided in each aspect as described below.

[0059] (1) A mine detection system for detecting landmines, comprising: a first drone device, the first drone device having an X-ray irradiation device that irradiates X-rays; a second drone device, the second drone device having an X-ray detection device that detects X-rays; and a control unit, wherein the control unit has a detection mode in which backscattering of X-rays irradiated from the X-ray irradiation device of the first drone device is detected by the X-ray detection device of the second drone device.

[0060] (2) The mine detection system described in (1), wherein the control unit has a pre-measurement mode in which the X-ray values ​​of the natural environment at the search point are detected and recorded by the X-ray detection device of the second drone device before starting irradiation from the X-ray irradiation device.

[0061] (3) The mine detection system described in (1), wherein the control unit has a low-altitude irradiation mode that causes the X-ray irradiation device to irradiate X-rays while the first drone device is hovering at a height ranging from 30 cm to 100 cm above the ground.

[0062] (4) The mine detection system described in (1), wherein the control unit has a landing irradiation mode that causes the X-ray irradiation device to irradiate X-rays while the first drone device is landed on the ground.

[0063] (5) The mine detection system described in (1), wherein the control unit has a first detection mode that positions the second drone device above the first drone device when X-ray irradiation is performed by the X-ray irradiation device of the first drone device.

[0064] (6) The mine detection system described in (1), wherein the second drone device forms a team of between two and nine drones, and the control unit has a deployment mode in which X-ray detection is performed by the X-ray detection device while the second drone device is positioned at equal intervals circumferentially on a circle centered on the first drone device in a top view.

[0065] (7) The mine detection system described in (1), wherein the second drone devices form a team of two or more, and the control unit has an altitude difference mode in which any of the second drone devices performs detection using the X-ray detection device at a first altitude, and any of the remaining second drone devices performs detection using the X-ray detection device at a second altitude higher than the first altitude.

[0066] (8) The mine detection system described in (1), wherein the control unit has a mobile detection mode in which, while the first drone device is irradiating X-rays using the X-ray irradiation device, the control unit causes the X-ray detection device of the second drone device to detect X-rays at a first location, and the second drone device, which has detected X-rays at the first location, is moved to a second location and causes the X-ray detection device of the second drone device to detect X-rays at the second location.

[0067] (9) The first drone device is equipped with a tank for storing colored liquid and a coloring unit that drops the colored liquid from the tank, and the control unit is equipped with a mark mode in which the coloring unit drops the colored liquid from the tank at a predetermined search point (when it determines that a predetermined object has been detected), leaving a mark on the ground.The mine detection system described in (1)

[0068] (10) The mine detection system described in (1), wherein the control unit has a course setting mode that executes control to detect backscattered X-rays using the X-ray detection device of the second drone device at multiple points along a predetermined course.

[0069] (11) The mine detection system described in (1), wherein the second drone device is equipped with an earthing metal wire that extends from the body of the second drone device to the ground at the altitude at which detection is performed by the X-ray detection device.

[0070] (12) A mine detection method for detecting landmines, comprising an irradiation step of irradiating the ground with X-rays from an X-ray irradiation device provided in a first drone device, and a detection step of detecting backscattering of the X-rays irradiated in the irradiation step using an X-ray detection device provided in a second drone device.

[0071] The embodiments for carrying out the present invention are not limited to the above, and other modifications may be applied. Various alternative embodiments and examples will be apparent to those skilled in the art based on the disclosed technology. In this embodiment, the X-ray irradiator 8 irradiates X-rays when the first drone 6 of the first drone device 2 is located at a predetermined altitude H, for example, 30 cm above the ground G. However, as shown in FIG. 14 , the X-ray irradiator 8 may irradiate X-rays when the first drone 6 of the first drone device 2 has landed on the ground G. For example, the control unit 30 controls the X-ray irradiator 8 to irradiate X-rays when the first drone device 2 has landed on the ground using the landing irradiation mode 39. This allows the X-ray irradiator 8 to irradiate X-rays from a distance close to the mine while the first drone device 2 is stable on the ground. This further improves the accuracy of mine detection. The first drone 6 can take off and land automatically in response to a command from the control unit 30. Therefore, the first drone 6 lands before the X-ray irradiator 8 irradiates X-rays. This not only allows stable X-ray irradiation while the X-ray irradiator 8 is installed, but also makes it easier to increase the intensity of backscattered X-rays by shortening the distance between the X-ray irradiator 8 and the landmine M. When the X-ray irradiator 8 irradiates X-rays while the first drone 6 has landed on the ground G, the altitude of the X-ray detection device 22 of the second drone 4 can be lowered, improving the detection accuracy of the X-ray detection device 22. Even when the first drone 6 lands, backscattered X-rays 52 can be detected using multiple second drones 4. The modified example in which the first drone 2 lands can be combined with any arrangement or configuration of the second drone 4 in the embodiment. Furthermore, at search points where landing is possible, the control unit 30 may execute the landing irradiation mode 39, and at search points where landing is difficult, the X-ray irradiator 8 may irradiate X-rays from the air. [Explanation of symbols]

[0072] 1: Landmine detection system 2: First drone device 4: Second drone device 6: First drone 6a: Aircraft body 8:X-ray irradiation device 20: Second drone 20a: Aircraft body 22: X-ray detection device 30: Control section

Claims

1. 1. A mine detection system for detecting a land mine, comprising: a first drone device, the first drone device including an X-ray irradiation device that irradiates X-rays as a beam having a predetermined diameter on the ground; a second drone device, the second drone device including an X-ray detection device for detecting X-rays; a control unit; The control unit has a detection mode in which the X-ray detection device of the second drone device detects backscatter caused by X-rays irradiated as a beam having a predetermined diameter on the ground from the X-ray irradiation device of the first drone device hitting the landmine; a first detection mode in which the second drone device is positioned above the first drone device when X-ray irradiation is performed by the X-ray irradiation device of the first drone device; the control unit causes the X-ray irradiation device to irradiate X-rays while the first drone is hovering at a height ranging from 30 cm to 100 cm above the ground or while the first drone is landing on the ground; The control unit of the mine detection system is equipped with a mobile detection mode in which, while the first drone device is irradiating X-rays using the X-ray irradiation device, the control unit causes the X-ray detection device of the second drone device to detect X-rays at a first location, and the second drone device, which has detected X-rays at the first location, is moved to a second location and causes the X-ray detection device of the second drone device to detect X-rays at the second location.

2. 2. The mine detection system of claim 1, wherein the control unit has a pre-measurement mode in which, before starting irradiation from the X-ray irradiation device, the X-ray values ​​of the natural environment at the search point are detected and recorded by the X-ray detection device of the second drone device.

3. The second drone device forms a team with a number of drones ranging from 2 to 9, 2. The mine detection system of claim 1, wherein the control unit has a deployment mode in which the X-ray detection device detects X-rays while the second drone is positioned at equal intervals circumferentially around a circle centered on the first drone in a top view.

4. The second drone device forms a team of two or more drones, 2. The mine detection system of claim 1, wherein the control unit is provided with an altitude difference mode in which any of the second drone devices performs detection using the X-ray detection device at a first altitude, and any of the remaining second drone devices performs detection using the X-ray detection device at a second altitude higher than the first altitude.

5. The first drone device includes a tank that stores a coloring liquid and a coloring unit that drops the coloring liquid from the tank, 2. The landmine detection system according to claim 1, further comprising a mark mode in which the control unit drops coloring liquid from the tank at a predetermined search point (when it determines that a predetermined object has been detected) and leaves a mark on the ground by the coloring unit.

6. 2. The mine detection system of claim 1, wherein the control unit has a course setting mode that executes control to detect backscattered X-rays by the X-ray detection device of the second drone device at multiple points along a predetermined course.

7. 2. The mine detection system of claim 1, wherein the second drone device is equipped with an earthing metal wire that extends from the body of the second drone device to the ground at an altitude where detection is performed by the X-ray detection device.

8. A mine detection method for detecting a land mine, comprising: an irradiation step of irradiating the ground with X-rays from an X-ray irradiation device provided in the first drone device as a beam having a predetermined diameter on the ground; a detection step of detecting backscattering of the X-rays emitted as a beam having a predetermined diameter on the ground in the irradiation step by an X-ray detection device provided in the second drone device when the X-rays hit the landmine; the control unit disposes the second drone device above the first drone device when X-ray irradiation is performed by the X-ray irradiation device of the first drone device; the control unit causes the X-ray irradiation device to irradiate X-rays while the first drone is hovering at a height in a range of 30 cm to 100 cm above the ground or while the first drone is landing on the ground; A mine detection method in which, in a moving detection mode, the control unit causes the X-ray detection device of the second drone device to detect X-rays at a first location while the first drone device is irradiating X-rays using the X-ray irradiation device, and also causes the second drone device, which has detected X-rays at the first location, to move to a second location and cause the X-ray detection device of the second drone device to detect X-rays at the second location.

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