Unmanned aerial vehicle, mine detection system, and mine detection method

Abstract

Applying unmanned aerial vehicle technology to landmine detection operations will improve the reliability, safety, and efficiency of landmine detection. [Solution] This problem can be solved by an unmanned aerial vehicle equipped with multiple rotors and mine sensors, the mine sensors having a sensor part that rotates or turns in the horizontal direction; a mine detection system that changes the display of each part on map data according to the possibility that mines are installed; or a mine detection method that includes a mine search process in which an unmanned aerial vehicle autonomously flies along a flight path while rotating or turning the sensor part while maintaining a distance of 30 cm or less between the sensor part and the ground surface.

Description

Technical Field

[0001] The present invention relates to unmanned aerial vehicle technology. Background Art

[0002] Patent Document 1 below discloses an aerial robot provided with a metal detection sensor and capable of detecting landmines. Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2005-288661 Summary of the Invention Problems to be Solved by the Invention

[0004] Unattended landmines, which are remnants of wars and armed conflicts, continue to threaten the lives and livelihoods of people for many years even after the end of conflicts. Unattended landmines constitute a serious humanitarian issue and also act as a factor hindering the reconstruction of affected countries.

[0005] In order to remove such unattended landmines, destruction operations using heavy machinery (such as flails, rollers, cutters, etc.) and search operations using metal detectors and the like have been continued. Particularly in areas where it is difficult to bring in heavy machinery, it is necessary to excavate and recover landmines or perform pinpoint destruction by remote detonation, and the reliability of detection and the accuracy of detected positions determine the success or failure and safety of the operation.

[0006] The problem to be solved by the present invention is to improve the reliability, safety, workability and the like of landmine detection by applying unmanned aerial vehicle technology to landmine detection work. Means for Solving the Problem

[0007] To solve the above problems, the gist of the present invention is that the unmanned aerial vehicle comprises a plurality of rotors and a mine sensor for detecting planted mines, wherein the mine sensor has a sensor part that rotates or rotates in the horizontal direction.

[0008] By equipping unmanned aerial vehicles with mine sensors and rotating or oscillating the sensor unit while searching for mines, it becomes possible to search for mines more safely and efficiently.

[0009] In the present invention, the mine sensor may have a plurality of sensor units that are rotationally mounted on a common axis of rotation or pivot. By searching a single search area with multiple sensor units, mines can be detected with higher accuracy or more efficiently.

[0010] In the present invention, the mine sensor may have a plurality of sensor units, and each sensor unit may be a sensor that detects a mine using a different principle. By combining sensors with different functions and characteristics, the accuracy of mine detection can be further improved.

[0011] In the present invention, the mine sensor has a plurality of sensor units and a plurality of shaft units which are rotating or pivoting shafts to which these sensor units are attached, and these shaft units may be arranged in a horizontal line. By arranging the plurality of shaft units in a horizontal line, that is, by using the plurality of sensor units in parallel, it becomes possible to search a wide area in a shorter time or to search more thoroughly.

[0012] The unmanned aerial vehicle of the present invention preferably further comprises a GNSS receiving unit that acquires position information from a GNSS (Global Navigation Satellite System), a correction information receiving unit that acquires correction information for the position information, and a ground altitude sensor that is a sensor capable of measuring the distance to the ground. For example, by using position correction information such as RTK (Real Time Kinematic), it is possible to achieve centimeter-level positional accuracy for the latitude, longitude, and altitude (ellipsoid height) of the unmanned aerial vehicle, thereby improving the accuracy of identifying the location of landmines.

[0013] The unmanned aerial vehicle of the present invention is preferably further equipped with a marking means for marking locations where the presence of landmines is suspected based on the output value of the landmine sensor. This is to enable safer and more efficient recovery and destruction operations after landmine detection.

[0014] In this invention, the rotation plane of each rotor may be inclined such that its surface position is lower toward the center of the aircraft. Beneath an unmanned aerial vehicle (UAV) flying near the ground with multiple rotors, the downwash from each rotor converges and collides toward the center of the aircraft, creating an upward fountain-like airflow (a so-called fountain flow). The fountain flow acts to collect grass and dust from the ground toward the center of the aircraft. When searching for landmines directly beneath the UAV, the grass and other debris collected toward the center of the aircraft hinders the search. By inclining the rotation plane of each rotor so that its surface position is lower toward the center of the aircraft, that is, by giving each rotor a so-called outward cant, the fountain flow is reduced and the accuracy of landmine detection is improved.

[0015] Furthermore, in order to solve the above problems, the mine detection system of the present invention comprises an unmanned aerial vehicle of the present invention and a display device that displays map data, wherein the display device changes the display of each part on the map data according to the possibility that a mine is installed.

[0016] When unmanned aerial vehicle (UAV) exploration and the removal of detected landmines are performed separately, it is necessary to accurately communicate to the removal workers where and what was detected. By equipping the UAV with a display device that shows the exploration results on map data, landmine removal operations can be carried out more safely and efficiently.

[0017] Furthermore, in order to solve the above problems, the present invention provides a mine detection method that includes a flight planning step of specifying the flight path of the unmanned aerial vehicle on map data, and a mine detection step of autonomously flying the unmanned aerial vehicle along the flight path while rotating or oscillating the sensor unit while maintaining the distance between the sensor unit and the ground surface at 30 cm or less.

[0018] By equipping unmanned aerial vehicles with mine sensors and rotating or oscillating the sensor unit while searching for mines, it becomes possible to search for mines more safely and efficiently.

[0019] In the present invention, the mine sensor has a plurality of sensor units and a plurality of shaft units to which these sensor units are attached, and these shaft units are arranged in a horizontal direction, and in the mine detection process, the unmanned aerial vehicle may be flown so that each of the shaft units moves parallel to each other in the mine search area. This makes it possible to search a wide area in a shorter time. [Effects of the Invention]

[0020] The unmanned aerial vehicle, mine detection system, and mine detection method of the present invention can improve the reliability, safety, and workability of mine detection. [Brief explanation of the drawing]

[0021] [Figure 1] This is a perspective view of the multicopter 10. [Figure 2] This is a bottom view of the multicopter 10. [Figure 3]It is a block diagram showing the functional configuration of a landmine detection system 90. [Figure 4] It is a schematic diagram showing the autopilot operation of a multicopter 10. [Figure 5] It is a side view of the multicopter 10 during landmine exploration. [Figure 6] It is a schematic diagram showing a method for identifying landmine positions. [Figure 7] It is a schematic plan view showing a modified example of the multicopter 10. [Figure 8] It is a perspective view and a schematic plan view showing a modified example of the multicopter 10. Description of Embodiments

[0022] <Outline of Configuration> Hereinafter, embodiments of the present invention will be described with reference to the drawings. The landmine detection system described below is an embodiment characterized in that a landmine sensor is mounted on a multicopter, which is an unmanned aerial vehicle, and the multicopter is caused to fly over a landmine area while rotating a sensor unit of the landmine sensor near the ground surface. Hereinafter, this feature of the present invention and other features associated therewith will be described taking the landmine detection system as an example.

[0023] Figure 1 is a perspective view of a multicopter 10. Figure 2 is a bottom view of the multicopter 10. Hereinafter, the airframe structure of the multicopter 10 will be described with reference to Figures 1 and 2.

[0024] The multicopter 10 in this example has a mount bar 14, which is a long, straight rod-shaped frame part extending horizontally. Two box-shaped, hollow rotor hubs 13 are fixed on the mount bar 14, and a LiDAR (Light Detection and Ranging) 39 is fixed between these two rotor hubs 13. Four arms 12 are connected to each rotor hub 13 at equal angles along its circumferential direction when viewed from above. A rotor 11, consisting of a fixed-pitch propeller and a motor, is supported at the tip of each arm 12. The LiDAR 39 scans the terrain around the multicopter 10. As will be described later, the LiDAR 39 in this example also functions as a ground altitude sensor to measure the distance between the multicopter 10 and the ground surface.

[0025] A mine sensor 20 for detecting mines placed on or in the ground is attached below the mounting bar 14. The mine sensor 20 in this example has five sensor pairs, each consisting of two sensor units attached rotationally symmetrically to a shaft 21 (see Figure 2), which is a rotating axis. The shafts 21 are arranged at equal intervals along the longitudinal direction of the mounting bar 14. By arranging multiple shafts 21 horizontally, that is, by using multiple sensor units in parallel, the mine sensor 20 in this example makes it possible to search a wide area in a shorter time or to search more thoroughly. In this example, the shaft 21 is a rotating axis that keeps the sensor units rotating in the same direction at a constant speed, but the shaft 21 may also be a pivot axis that moves each sensor unit back and forth within a specific angular range (for example, a range of 180 degrees).

[0026] In this example, each shaft 21 is equipped with a metal detection sensor 22 and a GPR (Ground Penetrating Radar) sensor 23 as sensor units. The metal detection sensor 22 is a sensor that detects metal by electromagnetic induction or pulse induction. The GPR sensor 23 is a sensor that detects the shape of foreign objects underground from radar wave echoes. In this example, by combining the metal detection sensor 22 and the GPR sensor 23, which have different functions and characteristics, it is possible to, for example, select landmines from among a large number of detected metal objects or to detect non-metallic landmines. Hereinafter, the metal detection sensor 22 and the GPR sensor 23 will be collectively referred to as "sensors 22, 23," and each set of metal detection sensors 22 and GPR sensors 23 attached to the shaft 21 will be referred to as "sensor pair 22, 23." Furthermore, the types of sensors used in the mine sensor 20 are not limited to the metal detection sensor 22 and the GPR sensor 23; other known mine detection sensors, such as magnetic sensors, optical sensors, and chemical sensors, can also be used.

[0027] A simple skid 15, which is a landing gear, is fixed to the middle of the mount bar 14 in the longitudinal direction. In this example, a marking spray 40 (see Figure 2) that sprays colored water is attached to the skid 15. The marking spray 40 is an example of a marking means that marks the ground surface at locations where the presence of landmines is suspected, based on the output value of the landmine sensor 20.

[0028] <Functional Configuration> Figure 3 is a block diagram showing the functional configuration of the mine detection system 90 in this example. The functions of the multicopter 10 and GCS (ground control station) 50 that constitute the mine detection system 90 will be explained below with reference to Figure 3. Note that the block diagram in Figure 3 only shows features that are particularly noteworthy in this example; commonly used components such as the ESC (Electronic speed controller), PDB (Power Distribution Board), communication module between the multicopter 10 and GCS 50, battery, and various mechanical switches are omitted.

[0029] The basic flight functions of the multicopter 10 are realized by the flight controller 30, GNSS receiver 33, RTK receiver 34, LiDAR 39, and rotor 11.

[0030] The flight controller 30 is a control system that includes a microcontroller, an IMU (Inertial Measurement Unit), a barometric pressure sensor, an electronic compass, and the like. The flight controller 30 is not limited to a standalone control system, but may be combined with a so-called companion computer. Alternatively, it could be configured using, for example, an FPGA (field-programmable gate array) or an ASIC (Application Specific Integrated Circuit).

[0031] The GNSS receiver 33 and the RTK receiver 34 are external devices connected to the flight controller 30. The RTK receiver 34 is a correction information receiving unit that receives correction information to correct errors in position information acquired from GNSS, either directly from a fixed reference station or via the Internet from an NTRIP (Networked Transport of RTCM via Internet Protocol) caster. By applying this correction information to the received signal from GNSS, the longitude, latitude, and altitude (ellipsoid height) of the multicopter 10 can be improved to centimeter-level accuracy.

[0032] Furthermore, while the altitude values ​​from the GNSS receiver 33 and the barometric pressure values ​​from the barometric pressure sensor can only determine the relative altitude of the multicopter 10 relative to its takeoff point, as mentioned above, the multicopter 10 in this example measures its altitude relative to the ground around the aircraft with high precision using the LiDAR 39. The means by which the multicopter 10 can acquire its altitude relative to the ground in a mine-detection area are not limited to the LiDAR 39; for example, ranging sensors using lasers, radars, infrared, ultrasound, parallax, etc., can also be used.

[0033] The flight controller 30 is equipped with a flight stack, which is a group of modules that control the attitude and basic flight movements of the multicopter 10 during flight. The flight stack is sometimes called flight firmware or autopilot program. Based on information acquired from various sensors, the flight controller 30 adjusts the rotation speed of each rotor 11 and flies the multicopter 10 while correcting the tilt, rotation, and positional disturbances of the aircraft.

[0034] The flight stack of the flight controller 30 also includes a program for autonomously flying the multicopter 10. The flight controller 30 receives a flight plan from the GCS 50, which is data specifying the destination, waypoints, altitude, and speed of the multicopter 10, and can make the multicopter 10 fly autonomously according to the flight plan.

[0035] Thus, the multicopter 10 in this example is an unmanned aerial vehicle equipped with advanced flight control functions. The unmanned aerial vehicle of the present invention is not limited to the form of the multicopter 10 in this example, and for example, an aircraft with some sensors omitted or an aircraft that does not have autonomous flight functions and can be flown only by manual control can also be used.

[0036] The GCS50 is a management device that is directly wirelessly connected to the multicopter 10 or wirelessly connected via the internet. The GCS50 is a device that allows the operator to create and upload flight plans for the multicopter 10, receive telemetry data from the multicopter 10 to monitor the status of the multicopter 10 in flight, analyze the output values ​​of the mine sensor 20 and process them for display, send commands to the multicopter 10 based on the analysis results, and manually control the multicopter 10. The GCS50 may be a device designed specifically for the mine detection system 90, or it may be a general-purpose PC or tablet device with the necessary software and applications installed.

[0037] The GCS50 is equipped with a general user interface 59, including a display (or touch panel) as a display device and a keyboard and mouse (or trackball) as input devices. The GCS50 also includes a map display program 51, a flight plan creation program 52, a flight monitoring program 53, a sensor value analysis program 54, and a control transmitter 55.

[0038] The map display program 51 displays map data of the mine detection area on the GCS 50's display. The operator uses the flight plan creation program 52 to create a flight plan 521 on the map data 511, for example, as shown in Figure 4(a), and uploads it to the multicopter 10. The flight monitoring program 53 receives telemetry data from the multicopter 10 and displays the status of the multicopter 10 in flight on the display (the so-called flight data screen). The sensor value analysis program 54 analyzes the output value or processed value of the mine sensor 20 received from the multicopter 10 and displays the location of the mines on the map data 511 as icons 541, for example, as shown in Figure 6(b). The control transmitter 55 is a device for manually controlling the multicopter 10, and may be, for example, a specific key on a keyboard, a touch panel, or a so-called radio control system.

[0039] Here, regarding the sensor value analysis program 54, in landmine detection using a combination of the metal detection sensor 22 and the GPR sensor 23, it is desirable to utilize the characteristics of both sensors complementarily. As mentioned above, the metal detection sensor 22 is a sensor that detects metal, but it also reacts to metal fragments other than landmines, resulting in an extremely high false alarm rate. On the other hand, the GPR sensor 23 can detect non-metallic landmines, but its reliability can be compromised by noise such as soil heterogeneity. By analyzing the waveforms and reflection intensity of the output values ​​of both sensors using a machine learning algorithm and integrating them (sensor fusion), the accuracy of the sensor value analysis program 54 in distinguishing landmine-specific signal patterns can be improved. In real-world environments, there are challenges such as fluctuations in soil conditions, methods for synchronizing data from both sensors, and the real-time nature of the analysis process. However, by accumulating learning, it is possible to detect non-metallic landmines and landmines with low metal content, reduce false alarms from metal fragments that are not landmines, and improve the safety and efficiency of landmine removal.

[0040] Furthermore, the mine sensor 20 in this example is equipped with an encoder that detects the arrangement angle of each shaft portion 21 in real time, and the output values ​​of each sensor 22, 23 are linked to the latitude and longitude with centimeter accuracy. In addition, the marking spray 40 in this example is equipped with a movable nozzle (not shown), and its spray direction can be changed according to the output value of the mine sensor 20 and the instructions of the sensor value analysis program 54.

[0041] <Landmine detection method> Figure 4 is a schematic diagram showing the autopilot operation of the multicopter 10. Figure 5 is a side view of the multicopter 10 during mine detection. Figure 6 is a schematic diagram showing the method for identifying the location of a mine. The mine detection method using the mine detection system 90 will be described below with reference to Figures 4 to 6.

[0042] (Flight planning process) As shown in Figure 4(a), when starting a mine search, the operator first displays map data 511, which includes the mine search area (area enclosed by a dashed line), on the GCS 50 display. Then, the operator specifies the flight path of the multicopter 10 on the map data 511 and creates a flight plan 521. The numbers shown in Figure 4(a) represent the order in which the multicopter 10 passes through waypoints. Although not shown in Figure 4(a), the flight path data also includes parameters such as altitude above ground, flight speed, and heading at each point. The operator uploads the created flight plan 521 from the GCS 50 to the multicopter 10. Note that the flight plan 521 data is not limited to being uploaded to the multicopter 10 in advance and stored there; for example, commands could be automatically sent sequentially from the GCS 50 to the multicopter 10.

[0043] (Mine detection process) Upon receiving flight plan 521, the multicopter 10, following instructions from the GCS 50, begins searching for landmines. Specifically, as shown in Figure 5, the multicopter 10 autonomously flies along flight plan 521 while rotating the sensors 22 and 23, maintaining a distance L between the sensors 22 and 23 and the ground surface of 30 cm or less. Each sensor 22 and 23 repeatedly scans a circular area with a radius equal to the distance from the shaft 21 to which it is mounted, to the tip of each sensor 22 and 23. This expands the scan width and scan area of ​​each sensor 22 and 23 in a single straight flight compared to when their arrangement angles are fixed. Since detection accuracy is improved when the sensors 22 and 23 are closer to the ground surface, it is desirable to keep the distance to 20 cm or less if possible, and even closer if the ground surface is flat and there are few disturbances, so that the sensors 22 and 23 barely touch the ground surface.

[0044] In this example, the skid 15 is positioned so that its contact surface is slightly below the bottom surface of sensors 22 and 23. This is to prevent sensors 22 and 23 from touching the ground when the multicopter 10 lands, and to ensure that the distance between the contact surface and the ground is as long as possible when detecting landmines. The skid 15 may also be a retractable gear.

[0045] In this example, an unmanned aerial vehicle that flies with multiple fixed-pitch propellers, such as the multicopter 10, needs to tilt when moving horizontally in order to obtain thrust in that direction. Since the sensors 22, 23 and their shafts 21 are fixed in position to the mounting bar 14 that constitutes the frame of the multicopter 10, the sensors 22, 23 will also tilt when the multicopter 10 tilts. In the mine detection process, the multicopter 10 moves at a speed (tilt) such that the tilt of the sensors 22, 23 does not interfere with mine detection. If the tilt of the sensors 22, 23 becomes a problem, the shafts 21 and the sensors 22, 23 can be supported by a stabilizer such as a known three-axis gimbal.

[0046] Furthermore, as shown in Figure 5, in this example, the rotation plane S of each rotor 11 of the multicopter 10 is tilted so that its plane position becomes lower toward the center of the aircraft. Beneath an unmanned aerial vehicle flying near the ground with multiple rotors, a fountain flow is generated when the downwash of each rotor converges and collides toward the center of the aircraft. The fountain flow acts to collect grass and dust from the ground toward the center of the aircraft. In this example, the multicopter 10 is used to search for landmines directly beneath the aircraft, so the grass and other debris collected toward the center of the aircraft would hinder the search. In this example, the fountain flow is mitigated by arranging each rotor 11 with a so-called outward cant, thereby improving the accuracy of landmine detection.

[0047] Furthermore, as shown in Figure 4(b), the multicopter 10 uses an electronic compass built into the flight controller 30 to control its heading so that the five sensor pairs 22 and 23 are aligned perpendicular to the direction of travel of the multicopter 10. In other words, it maintains its heading so that the five sensor pairs 22 and 23 move parallel to the direction of travel. This also widens the scan width in a single straight flight, allowing a wider search area to be explored in a shorter time. In addition, the multicopter 10 can further improve the accuracy of mine detection by controlling its heading so that part or all of the scan ranges of each sensor pair 22 and 23 intentionally overlap.

[0048] As shown in Figure 6(a), the multicopter 10, while flying autonomously, marks the ground surface at locations suspected of having landmines with marking spray 40, based on the output value of the landmine sensor 20. The multicopter 10 may independently determine whether marking is necessary by setting a threshold for the output value of the landmine sensor 20, or the sensor value analysis program 54 of the GCS 50 may analyze the output value of the landmine sensor 20 in real time and perform marking based on instructions from the sensor value analysis program 54.

[0049] The GCS50 analyzes the output values ​​of the mine sensor 20 received from the multicopter 10 using the sensor value analysis program 54. Then, as shown in Figure 6(b), it displays icons 541 at locations on the map data 511 where the presence of mines is suspected.

[0050] In this example, the location of landmines can be visually identified by marking the ground surface with marking spray 40 and displaying icons 541 on the GCS 50 map data 511. This makes subsequent landmine recovery and destruction operations safer and more efficient. In particular, when the search operation using the multicopter 10 and the operation of removing detected landmines are separated, the location of the landmines can be accurately and clearly indicated to the removal workers, thereby improving the safety and efficiency of landmine removal operations. In this example, icons 541 are used to identify the location of landmines on the map data 511, but the method of identifying the location of landmines is not limited to icons 541. Other methods can be adopted as long as they change the display of various parts on the map data 511 according to the possibility of landmines being present. For example, the strength of the output values ​​of sensors 22 and 23 at each point in the landmine search area could be represented by color, or the degree of the possibility of landmines being present could be represented by color.

[0051] The marking spray 40 and the icon 541 may be performed individually or in a simpler form. For example, this could be necessary if the mine search area is relatively small and it is sufficient to determine whether or not there are mines in the area, or if only a rough location marking is required. Alternatively, if the removal worker follows behind the multicopter 10 and performs confirmation and removal work on the spot whenever a mine-like shadow is detected, the marking spray 40 and icon 541 could be omitted, for example, by the multicopter 10 sounding a buzzer or flashing / illuminating a high-intensity light as a signal of detection.

[0052] Thus, the mine detection system 90 in this example improves the safety and efficiency of mine detection work by mounting a mine sensor 20 on a multi-rotor aircraft 10, which is an unmanned aerial vehicle, and having the multi-rotor aircraft 10 fly over a minefield while rotating the sensors 22 and 23 of the mine sensor 20 near the ground surface.

[0053] <Variation> Figures 7 and 8 are schematic plan views and perspective views, respectively, showing modified configurations of the multicopter 10. Modified configurations of the multicopter 10 will be described below with reference to Figures 7 and 8.

[0054] Figure 7 shows an example of an aircraft configuration to which a typical flight stack can be applied. In this example, the multicopter 10 has a configuration in which four rotors 11 are arranged in a manner similar to a quadcopter, with two sets of rotors 11 placed on a mounting bar 14. There are a total of eight rotors 11, but because the arrangement of the rotors 11 differs from that of a typical octacopter, a typical flight stack cannot be used as is, and some degree of customization is required.

[0055] Therefore, by arranging each arm 12 to extend radially from the center of the aircraft, as in the multicopter 10a shown in Figure 7(a), the configuration can be made closer to that of an octacopter. This makes it possible to adopt a highly reliable flight stack with a proven track record with minimal modifications, thereby reducing the development and maintenance costs of the aircraft. Alternatively, as in the multicopter 10b shown in Figure 7(b), the two arms 12 and their rotors 11 that extend from each rotor hub 13 toward the center of the aircraft are removed from the multicopter 10, resulting in a so-called hexacopter configuration overall.

[0056] Figure 8 shows further variations of the configuration of the multicopter 10. The multicopter 10 in the above embodiment is configured to efficiently search a wide area for mine detection, but a smaller aircraft may be more suitable for searching narrow areas or areas with many obstacles. The multicopter 10c in Figure 8(a) is the minimum configuration of the multicopter 10. The multicopter 10c is a quadcopter equipped with only one rotating or rotatable metal detection sensor 22 attached to a shaft portion 21 (not shown) as a mine sensor 20. Even when using the multicopter 10c, mine detection can be performed more safely and efficiently by searching for mines while rotating the metal detection sensor 22. The mine sensor 20 of the multicopter 10c may be configured such that the metal detection sensor 22 and the GPR sensor 23 are rotationally mounted on the shaft portion 21, similar to the multicopter 10. Alternatively, one could prepare two multi-rotor aircraft: one that uses a metal detection sensor 22 to search the mine-hunting area, and another that uses a GPR sensor 23.

[0057] The helicopter 10d in Figure 8(b) is an unmanned aerial vehicle with a so-called tandem helicopter configuration, equipped with two variable-pitch rotors 11a. In the above embodiment, the multicopter 10 performs attitude control and movement by adjusting the rotational speed of each rotor 11. On the other hand, the helicopter 10d performs attitude control and movement by adjusting the pitch angle of each rotor 11a. Control by pitch angle is more responsive to disturbances than control by rotational speed, enabling more precise and stable attitude control. In other words, the unmanned aerial vehicle of the present invention does not have to be a multicopter. That is, it does not have to be equipped with three or more rotors.

[0058] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the invention. [Explanation of Symbols]

[0059] 10, 10a, 10b, 10c: Multicopter (unmanned aerial vehicle), 10d: Helicopter (unmanned aerial vehicle), 11: Rotor, 11a: Variable pitch rotor, 12: Arm, 13: Rotor hub, 14: Mount bar, 15: Skid, 20: Mine sensor, 21: Shaft, 22: Metal detection sensor (sensor unit), 23: GPR sensor (sensor unit), 30: Flight controller, 33: GNSS receiver, 34: RTK receiver (supplementary) 39: Positive information receiving unit, 40: LiDAR unit (ground altitude sensor), 411: Marker, 50: GCS (display unit), 51: Map display program, 511: Map data, 52: Flight plan creation program, 521: Flight plan, 53: Flight monitoring program, 54: Sensor value analysis program, 541: Icon, 55: Control transmitter, 59: User interface, 90: Mine detection system

Claims

1. Multiple rotors, Equipped with a mine sensor to detect planted mines, The aforementioned mine sensor has a sensor unit that is capable of detecting mines by bringing it close to the ground surface, and during mine detection, the sensor unit is continuously rotated or spun horizontally. unmanned aircraft.

2. The aforementioned mine sensor has a plurality of sensor units that are rotationally mounted on a shaft which is a common axis of rotation or pivot axis. The unmanned aerial vehicle according to claim 1.

3. The aforementioned mine sensor has a plurality of sensor units, Each of the aforementioned sensor units is a sensor that detects landmines using a different principle. The unmanned aerial vehicle according to claim 1.

4. The mine sensor has a plurality of sensor units and a plurality of shaft units which are rotating shafts or pivot shafts to which these sensor units are attached, and these shaft units are arranged in a horizontal direction. The unmanned aerial vehicle according to claim 1.

5. A GNSS receiver unit that acquires location information from GNSS (Global Navigation Satellite System), A correction information receiving unit that acquires correction information for the aforementioned location information, It is further equipped with a ground altitude sensor, which is a sensor capable of measuring the distance to the Earth's surface, The unmanned aerial vehicle according to claim 1.

6. The system further includes a marking means for placing a marker on a location where the presence of a landmine is suspected, based on the output value of the aforementioned landmine sensor. The unmanned aerial vehicle according to claim 1.

7. The rotational surfaces of each rotor are inclined such that their surface position becomes lower toward the center of the machine. The unmanned aerial vehicle according to claim 1.

8. An unmanned aerial vehicle according to any one of claims 1 to 7, It comprises a display device that displays map data, The display device changes the display of each part on the map data depending on the possibility that landmines are present. Mine detection system.

9. A flight planning step of specifying the flight path of an unmanned aircraft according to any one of claims 1 to 7 on map data, The process includes a mine detection step in which the unmanned aerial vehicle autonomously flies along the flight path while rotating or turning the sensor unit, while maintaining the distance between the sensor unit and the ground surface at 30 cm or less. Landmine detection method.

10. The aforementioned mine sensor has a plurality of sensor units and a plurality of shaft units to which these sensor units are attached, and these shaft units are arranged in a horizontal line. In the aforementioned mine detection process, the unmanned aerial vehicle is flown so that each of the shafts moves parallel to each other within the mine search area. The mine detection method according to claim 9.

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