Unmanned aircraft, sensing system, and sensing method

Abstract

This unmanned aircraft comprises a machine body having a plurality of rotors, a distance measurement sensor attached facing downward to the machine body, a tilt sensor that measures the tilt angle of the machine body, and a control device. The control device causes the machine body to tilt by controlling the rotation of the plurality of rotors, in which state the control device calculates the altitude difference between the machine body and a measurement point of the distance measured by the distance measurement sensor, on the basis of the distance and the tilt angle measured by the tilt sensor, and outputs information indicating the altitude difference.

Description

Unmanned aerial vehicle, sensing system, and sensing method

[0001] The present disclosure relates to unmanned aerial vehicles, sensing systems, and sensing methods.

[0002] An unmanned aerial vehicle (UAV) is an aircraft that cannot carry a person due to its structure and can fly by remote control or automatic pilot. Rotary-wing unmanned aerial vehicles are unmanned aerial vehicles that obtain lift using propellers that rotate around an axis, i.e., rotors. Small unmanned aerial vehicles equipped with multiple rotors (multi-rotor UAVs) are also called "drones," "multirotors," or "multicopters," and are widely used for applications such as aerial photography, surveying, logistics, and pesticide spraying.

[0003] Patent Document 1 describes an unmanned aerial vehicle (unmanned flying object) that changes its flight position in conjunction with the operation of agricultural machinery.

[0004] Japanese Patent Application Laid-Open No. 2022-104737

[0005] The present disclosure provides a novel method and system for measuring the altitude difference between one or more points below an unmanned aerial vehicle and the unmanned aerial vehicle.

[0006] In an exemplary and non-limiting embodiment, the unmanned aerial vehicle of the present disclosure includes an airframe having multiple rotors, a distance measurement sensor attached facing downward to the airframe, an inclination sensor that measures the inclination angle of the airframe, and a control device. The control device, while tilting the airframe by controlling the rotation of the multiple rotors, calculates an altitude difference between the distance measurement point and the airframe based on the distance measured by the distance measurement sensor and the inclination angle measured by the inclination sensor, and outputs information indicating the altitude difference.

[0007] In an exemplary and non-limiting embodiment, the sensing system of the present disclosure includes a distance measurement sensor attached facing downward to a body of an unmanned aerial vehicle, an inclination sensor that measures the inclination angle of the body, and a processing device. The processing device calculates an altitude difference between the measurement point of the distance and the body based on the distance measured by the distance measurement sensor when the body is inclined and the inclination angle measured by the inclination sensor when measuring the distance, and outputs information indicating the altitude difference.

[0008] According to an embodiment of the present disclosure, it is possible to measure the altitude difference between the unmanned aerial vehicle and one or more points below the unmanned aerial vehicle, thereby making it possible to obtain information such as the altitude of the unmanned aerial vehicle or the slope angle of a slope with a simple configuration.

[0009] 8 is a block diagram schematically showing several examples of a rotary drive device that rotates rotors in an unmanned aerial vehicle having multiple rotors. FIG. 9 is a plan view schematically showing one basic configuration example of an unmanned aerial vehicle having multiple rotors. FIG. 10 is a side view schematically showing one basic configuration example of an unmanned aerial vehicle having multiple rotors. FIG. 11 is a plan view schematically showing another basic configuration example of an unmanned aerial vehicle having multiple rotors. FIG. 12 is a block diagram showing a basic configuration example of a battery-powered multicopter. FIG. 13 is a block diagram showing a basic configuration example of a series hybrid drive multicopter. FIG. 14 is a block diagram showing a basic configuration example of a parallel hybrid drive multicopter. FIG. 15 is a block diagram schematically showing an example configuration of a multicopter equipped with a sensing system. FIG. 16 is a side view schematically showing an example of a multicopter equipped with a ranging sensor. FIG. 17 is a diagram for explaining an altitude estimation method in this embodiment. FIG. 18 is a diagram for explaining an altitude estimation method in this embodiment. FIG. 19 is a diagram for explaining an example of distance measurement on sloping ground. FIG. 19 is a diagram for explaining the operation of estimating the tilt angle φ. FIG. 19 is a diagram for explaining the operation of ranging by a multicopter equipped with a LiDAR sensor with a beam scanning function. FIG. 19 is a flowchart showing a specific example of the operation of the control device in the example shown in FIG. Fig. 10 is a flowchart showing an example of the operation of the control device in the example shown in Fig. 9. Fig. 11 is a diagram showing an example of control based on the altitude difference between a measurement point and an aircraft. Fig. 12 is a block diagram showing an example of the hardware configuration of the control device. Fig. 13 is a schematic diagram showing an example of the configuration of a system including a multicopter.

[0010] An unmanned aerial vehicle with multiple rotors includes a rotary drive unit that rotates the rotors (hereinafter sometimes referred to as "propellers"). Hereinafter, such an unmanned aerial vehicle will be referred to as a "multicopters."

[0011] There are various configurations of the rotary drive device provided in a multicopter. Fig. 1A is a block diagram schematically illustrating four examples of the rotary drive device 3 in the present disclosure.

[0012] The first rotation drive device 3A shown in FIG. 1A has a plurality of electric motors (hereinafter referred to as "motors") 14 that rotate a plurality of rotors 2, and a battery 52 that stores power to be supplied to each motor 14. The battery 52 is, for example, a secondary battery such as a polymer lithium-ion battery. Each rotor 2 is connected to the output shaft of the corresponding motor 14 and rotated by the motor 14. In order to increase the payload and / or flight time, it is necessary to increase the power storage capacity of the battery 52. ​​The power storage capacity of the battery 52 can be increased by increasing the size of the battery 52, but increasing the size of the battery 52 results in an increase in weight.

[0013] The second rotation drive device 3B shown in FIG. 1A includes a power transmission system 23 mechanically connected to the rotor 2 and an internal combustion engine 7a that provides driving force (torque) to the power transmission system 23. The power transmission system 23 includes mechanical components such as gears or belts, and transmits torque from the output shaft of the internal combustion engine 7a to the rotor 2. The internal combustion engine 7a can efficiently generate mechanical energy by burning fuel. Examples of the internal combustion engine 7a include a gasoline engine, a diesel engine, and a hydrogen engine. The number of internal combustion engines 7a included in the rotation drive device 3B is not limited to one.

[0014] The third rotary drive device 3C shown in FIG. 1A includes multiple motors 14, a power buffer 9 that stores power to be supplied to each motor 14, a power generator 8 such as an alternator that generates power, and an internal combustion engine 7a that provides mechanical energy for the power generator 8 to generate electricity. A typical example of the power buffer 9 is a battery such as a secondary battery, but it may also be a capacitor. In the third rotary drive device 3C, even if the power buffer 9 does not have a large storage capacity, the power generator 8 generates power using the driving force (mechanical energy) of the internal combustion engine 7a, thereby enabling an increase in payload and / or flight time. This type of drive is called a "series hybrid drive." The power generator 8 and internal combustion engine 7a in the series hybrid drive are called a "range extender" because they extend the flight distance of the multicopter.

[0015] 1A includes a plurality of motors 14, a power buffer 9 that stores power to be supplied to each motor 14, a power generator 8 such as an alternator that generates power, an internal combustion engine 7a that provides driving force for generating power to the power generator 8, and a power transmission system 23 that transmits the driving force generated by the internal combustion engine 7a to a rotor 2 to rotate the rotor 2. At least one rotor 2 of the plurality of rotors 2 is rotated by the internal combustion engine 7a, and the other rotors 2 are rotated by the motor 14. In the fourth rotary drive device 3D, the mechanical energy generated by the internal combustion engine 7a can also be used to rotate the rotor 2 without being converted into electric power, thereby improving energy utilization efficiency. This type of drive is called a "parallel hybrid drive."

[0016] Fig. 1B is a plan view schematically illustrating one basic configuration example of multicopter 10. The configuration example of Fig. 1B includes the first rotational drive device 3A shown in Fig. 1A as the rotational drive device 3. That is, the rotational drive device 3 (3A) in this example includes a motor 14 and a battery 52. ​​Fig. 1C is a side view schematically illustrating multicopter 10.

[0017] 1B and 1C includes a plurality of rotors 2, an airframe 4, and an airframe frame 5 that supports the rotors 2 and the airframe 4. The airframe frame 5 supports the airframe 4 at its center and rotatably supports the plurality of rotors 2 with a plurality of arms 5A extending outward from the center. A motor 14 that rotates the rotors 2 is provided near the tip of each arm 5A. The airframe 4 and the airframe frame 5 are sometimes collectively referred to as the "airframe 11."

[0018] 1B, the multicopter 10 is a quad-type multicopter (quadcopter) having four rotors 2. The rotors 2 located on one diagonal line rotate in the same direction (clockwise or counterclockwise), while the rotors 2 located on different diagonal lines rotate in opposite directions.

[0019] The main body 4 includes a control device 4a that controls the operation of devices and components mounted on the multicopter 10, a group of sensors 4b connected to the control device 4a, a communication device 4c connected to the control device 4a, and a battery 52.

[0020] The control device 4 a may include, for example, a flight control device such as a flight controller and a host computer (companion computer). The companion computer can perform advanced arithmetic processing such as image processing, obstacle detection, and obstacle avoidance based on the sensor data acquired by the sensor group 4 b.

[0021] The sensor group 4b may include an acceleration sensor, an angular velocity sensor, a geomagnetic sensor, a barometric pressure sensor, an altitude sensor, a temperature sensor, a flow rate sensor, an imaging device, a laser sensor, an ultrasonic sensor, an obstacle contact sensor, and a Global Navigation Satellite System (GNSS) receiver. The acceleration sensor and the angular velocity sensor may be mounted on the airframe main body 4 as components of an IMU (Inertial Measurement Unit). Examples of the laser sensor may include, for example, a laser range finder used to measure the distance to the ground, and a two-dimensional or three-dimensional light detection and ranging (LiDAR).

[0022] The communication device 4c may include a wireless communication module for transmitting and receiving signals via an antenna to a transmitter or ground station (Ground Control Station (GCS)) on the ground, a mobile communication module using a cellular communication network, etc. The communication device 4c may receive signals such as control commands transmitted from the ground and transmit sensor data such as image data acquired by the sensor group 4b as telemetry information. The communication device 4c may have a function for communicating between multicopters and a satellite communication function. The control device 4a can be connected to a computer on the cloud via the communication device 4c. Some or all of the functions of the companion computer may be performed by the computer on the cloud.

[0023] The battery 52 is a secondary battery that can store power by charging and supply power to the motors 14 by discharging. The battery 52 and the multiple motors 14 operate to rotate the multiple rotors 2, generating a desired thrust. Each of the multiple rotors 2 typically has multiple blades with a fixed pitch angle, generating thrust through rotation. The pitch angle may be variable. The multiple rotors 2 do not all need to have the same diameter (propeller diameter); one or more rotors 2 may have a larger diameter than the other rotors 2. The thrust (static thrust) generated by the rotating rotors 2 is generally proportional to the cube of the rotor 2 diameter. Therefore, when rotors 2 with different diameters are included, the rotor 2 with the larger diameter may be referred to as the "main rotor," and the rotor 2 with the smaller diameter may be referred to as the "sub-rotor." Regardless of the diameter, the configuration of the rotary drive device 3 may include rotors 2 with a relatively larger thrust and rotors 2 with a relatively smaller thrust. In this case, the rotor 2 capable of generating a relatively large thrust may be referred to as the "main rotor," and the rotor 2 capable of generating a relatively small thrust may be referred to as the "sub-rotor." For example, the rotor 2 capable of generating a relatively large thrust per rotation may be referred to as the "main rotor," and the rotor 2 capable of generating a relatively small thrust per rotation may be referred to as the "sub-rotor." In one example, the main rotor may be disposed more inward than the sub-rotors. In other words, each rotor 2 may be disposed so that the distance from the center of the aircraft to the rotation axis of each main rotor is shorter than the distance from the center of the aircraft to the rotation axis of each sub-rotor.

[0024] In this example, the rotary drive device 3 includes a plurality of motors 14. As mentioned above, the rotary drive device 3 may include an internal combustion engine 7a.

[0025] FIG. 1D is a plan view schematically illustrating an example of the basic configuration of a multicopter 10 including a second rotational drive device 3B as the rotational drive device 3. In the example shown in FIG. 1D , an internal combustion engine 7a is supported by the airframe main body 4. In this example, the driving force generated by the internal combustion engine 7a is transmitted to multiple rotors 2 via multiple power transmission systems 23, causing each rotor 2 to rotate. The control device 4a can change the rotational speed of each rotor 2 by controlling each power transmission system 23. The rotational drive device 3B may include a mechanism for changing the pitch angle of each blade of the multiple rotors 2. In this case, the control device 4a may adjust the lift generated by each rotor 2 by controlling the mechanism to change the pitch angle of the blades.

[0026] In a "parallel hybrid drive" in which some of the multiple rotors 2 are rotated by the internal combustion engine 7a and the other rotors 2 are rotated by the motor 14, the internal combustion engine 7a and the battery 52 are supported on the aircraft body 4. At least one rotor 2 of the multiple rotors 2 is connected to the internal combustion engine 7a via the power transmission system 23, and the other rotors 2 are connected to the motor 14.

[0027] In such a parallel hybrid drive, the diameter of one or more rotors 2 rotated by the internal combustion engine 7a may be larger than the diameter of the other rotors 2 rotated by the motor 14. In other words, the internal combustion engine 7a may be used to rotate the main rotor, and the motor 14 may be used to rotate the sub-rotor. In such a case, the main rotor is primarily used to generate thrust, and the sub-rotor is used to generate thrust and for attitude control. The main rotor may also be called a "booster rotor," and the sub-rotor may also be called an "attitude control rotor."

[0028] In the case of a parallel hybrid drive, the internal combustion engine is used for both thrust generation and power generation. By selectively transmitting the driving force (torque) generated by the internal combustion engine to one or both of the rotor and the power generator, it is possible to achieve a good balance between thrust generation and power generation.

[0029] Equipping a multicopter with an internal combustion engine and using it to generate thrust and / or electricity contributes to increased payload and flight time. It is desirable to control the attitude of a multicopter by rotating the propellers with a motor, which has better response characteristics than an internal combustion engine. Therefore, in applications requiring precise control of the multicopter's attitude, it is desirable to employ a parallel hybrid drive or series hybrid drive to increase the payload and flight time. If the rotary drive device 3 is equipped with a mechanism for changing the pitch angle of each blade of the multiple rotors 2, the attitude can also be adjusted by changing the pitch angle of each blade.

[0030] Increased payload and flight time may further expand the applications of multicopters. For example, in the agricultural field, multicopters are currently being used for spraying pesticides or monitoring crop growth conditions. However, by connecting various ground implements (hereinafter, sometimes simply referred to as "implements") to a multicopter, various agricultural tasks can be performed from the air. Agricultural implements are sometimes called "implements." Examples of implements include sprayers that spray pesticides on crops, mowers, seeders, spreaders, rakes, balers, harvesters, plows, harrows, or rotary tillers. Work vehicles such as tractors are not included in the "implements" of this disclosure.

[0031] In the example shown in FIG. 1C , a work implement 200 is coupled to the multicopter 10. The work implement 200 can spray, for example, pesticides or fertilizers on a field or crops within the field. Increasing the payload and flight time allows for a larger and / or more versatile work implement 200. For example, by changing the work implement 200 coupled to the multicopter 10, a variety of ground tasks (agricultural operations) can be performed, including liquid and granular application of pesticides, fertilization, thinning, weeding, transplanting, direct seeding, and harvesting. The work implement 200 may be equipped with a mechanism such as a robotic hand. In this case, a single work implement 200 can perform a variety of ground tasks. If the work implement 200 has a sufficient space to accommodate materials, the work implement 200 can also be used to transport agricultural materials or harvested products over a wide area. The work implement 200 can be coupled to the multicopter 10 in a variety of ways. The multicopter 10 may suspend and tow the work machine 200 by a cable. The work machine 200 towed by the multicopter 10 can also perform ground work while being towed while the multicopter 10 is flying or hovering. The work machine 200 during work may be in the air or on the ground.

[0032] 1C , the multicopter 10 includes a power supply device 76. The power supply device 76 is a device that supplies power to the work machine 200 from a drive energy source, such as the battery 52 or the power generation device 8, included in the multicopter 10. Various functions of the work machine 200 can be performed using this power. The work machine 200 includes actuators such as motors that operate using power obtained from the power supply device 76 of the multicopter 10. The work machine 200 preferably includes a battery that stores power. The ESC 16 may be included in the control device 4a.

[0033] FIG. 2A is a block diagram showing an example of the basic configuration of a battery-powered multicopter 10. The battery-powered multicopter 10 includes multiple rotors 12, multiple motors 14 that rotate the rotors 12, multiple ESCs (electric speed controllers) 16 each having a motor drive circuit that drives the motors 14, a battery 52 that supplies power to the corresponding motors 14 via each ESC 16, a control device 4a that controls the multiple ESCs 16 to control attitude and perform flight, a sensor group 4b, a communication device 4c, and a power supply device 76 electrically connected to the battery 52. ​​For simplicity, FIG. 2A shows the rotors 12, motors 14, and ESCs 16 as a single block, but the number of rotors 12, motors 14, and ESCs 16 is actually multiple. This also applies to FIGS. 2B and 2C.

[0034] The control device 4a can receive control commands wirelessly, for example, from a ground station 6 located on the ground via the communication device 4c. The number of ground stations 6 is not limited to one and may be distributed across multiple locations. The communication device 4c can also receive control commands wirelessly from a control device operated by a pilot on the ground. The control device 4a may have the function of automatically or autonomously performing takeoff, flight, obstacle avoidance, and landing operations based on sensor data obtained from the sensor group 4b. The control device 4a may be configured to communicate with the work machine 200 connected to the power supply device 76 and acquire a signal indicating the status of the work machine 200 from the work machine 200. The control device 4a may also provide the work machine 200 with a signal that controls the operation of the work machine 200. Furthermore, the work machine 200 may generate a signal instructing the operation of the multicopter 10 and transmit it to the control device 4a. Such communication between the control device 4a and the work machine 200 can be performed via wired or wireless communication.

[0035] FIG. 2B is a block diagram showing an example of the basic configuration of a series hybrid drive multicopter 10. Similar to the battery-powered multicopter 10, the series hybrid drive multicopter 10 includes multiple rotors 12, multiple motors 14, multiple ESCs 16, a control device 4a, a sensor group 4b, and a communication device 4c. The illustrated series hybrid drive multicopter 10 further includes an internal combustion engine 7a, a fuel tank 7b for storing fuel for the internal combustion engine 7a, a power generation device 8 driven by the internal combustion engine 7a to generate electric power, a power buffer 9 for temporarily storing the electric power generated by the power generation device 8, and a power supply device 76 electrically connected to the power buffer 9. The power buffer 9 is, for example, a battery such as a secondary battery. The electric power generated by the power generation device 8 is supplied to the motor 14 via the power buffer 9 and the ESC 16. The electric power generated by the power generation device 8 may also be supplied to the work machine 200 via the power supply device 76.

[0036] FIG. 2C is a block diagram showing an example of the basic configuration of a parallel hybrid drive multicopter 10. Similar to the series hybrid drive multicopter 10, the parallel hybrid drive multicopter 10 includes multiple rotors 12, multiple motors 14 that respectively drive the multiple rotors 12, multiple ESCs 16, a control device 4a, a sensor group 4b, a communication device 4c, an internal combustion engine 7a, a fuel tank 7b, a power generator 8, a power buffer 9, and a power supply device 76. The parallel hybrid drive multicopter 10 further includes a drive train 27 that transmits the driving force of the internal combustion engine 7a, and a rotor 22 that rotates by receiving the driving force of the internal combustion engine 7a from the drive train 27. One of the rotor 12 and the rotor 22 may be referred to as the “first rotor” and the other as the “second rotor” to distinguish them from each other. The number of rotors 22 connected to the drive train 27 and rotating may be one or more.

[0037] In the parallel hybrid drive multicopter 10, the internal combustion engine 7a not only drives the power generation device 8 to generate electricity, but also mechanically transmits energy to the rotor 22 to rotate the rotor 22. On the other hand, in the series hybrid drive multicopter 10, all of the rotors 12 are rotated by the electric power generated by the power generation device 8. For this reason, in the series hybrid drive multicopter 10, if the power generation device 8 is, for example, a fuel cell, the internal combustion engine 7a is not an essential component.

[0038] As described above, there are various configurations of the multicopter 10. In any configuration, the multicopter 10 may be equipped with a sensing system that measures the distance from the aircraft to the ground as the altitude of the aircraft.

[0039] The sensing system according to an embodiment of the present disclosure includes a distance measurement sensor attached to the body of an unmanned aerial vehicle facing downward, an inclination sensor that measures the inclination angle of the body, and a processing device. The processing device calculates the difference in altitude between the distance measurement point and the body based on the distance measured by the distance measurement sensor and the inclination angle measured by the inclination sensor during distance measurement, and outputs information indicating the difference in altitude.

[0040] This configuration makes it possible to estimate, for example, the altitude of an unmanned aerial vehicle or the difference in altitude between a distance measurement point and a point directly below the unmanned aerial vehicle. The processing device may acquire information on changes in the height of a sloping ground surface by repeatedly measuring the distance using the ranging sensor while changing the inclination of the aircraft. This also makes it possible to estimate the inclination of the sloping ground surface. Below, an embodiment of an unmanned aerial vehicle (multicopter) equipped with such a sensing system will be described.

[0041] FIG. 3 is a block diagram schematically illustrating an example configuration of a multicopter 10 equipped with a sensing system 300. The multicopter 10 illustrated in FIG. 3 includes the same components as the multicopter 10 illustrated in FIG. 2A. However, the power supply device 76 and the work machine 200 illustrated in FIG. 2A are omitted from FIG. 3. FIG. 3 illustrates a distance measurement sensor 42, an inclination sensor 44, and an imaging device 46 as examples of the sensor group 4b. The control device 4a includes a processing device 34 and a storage device 37. The sensing system 300 in the example of FIG. 3 includes the control device 4a and the sensor group 4b.

[0042] For simplicity, the rotor 12, the motor 14, and the ESC 16 are each shown as a single block in Fig. 3, but there may be a plurality of rotors 12, motors 14, and ESCs 16. Although not shown in Fig. 3, the multicopter 10 may include an internal combustion engine 7a, a fuel tank 7b, and a power generation device 8, as shown in Fig. 2B or 2C. Furthermore, as shown in Fig. 2C, the multicopter 10 may include at least one rotor 22 driven by the internal combustion engine 7a. In this case, either a "series hybrid" or a "parallel hybrid" drive system may be adopted.

[0043] The distance measurement sensor 42 may be, for example, a laser sensor such as a laser range finder or a LiDAR sensor. The distance measurement sensor 42 may also be a scanning LiDAR sensor that changes the emission direction of a laser beam to measure distances in each of multiple directions. The distance measurement sensor 42 is not limited to a laser sensor, and may be another sensor with a distance measurement function, such as an ultrasonic sensor, a millimeter-wave radar, or a stereo camera. The distance measurement sensor 42 is attached to the airframe of the multicopter 10 facing downward. Note that, when a work implement 200 is connected to the airframe as in the example shown in FIG. 1C , the distance measurement sensor 42 may be attached to the work implement 200. The distance measurement sensor 42 may be configured to measure the distance to a measurement point located below the multicopter 10 and output a signal indicating the distance.

[0044] The distance measurement sensor 42 may be positioned to measure the distance from the airframe of the multicopter 10 to the ground or an object on the ground located vertically downward (i.e., directly below) when the airframe is not tilted. Here, "airframe not tilted" refers to a state in which the multicopter 10 is in an attitude in which the rotational axis of each rotor is substantially parallel to the vertical direction (hereinafter referred to as the "reference attitude"). For example, a state in which the multicopter 10 is hovering in a windless environment corresponds to a state in which the airframe is not tilted.

[0045] The tilt sensor 44 measures the tilt angle of the airframe of the multicopter 10 and outputs a signal indicating the tilt angle. The tilt angle represents the magnitude of the tilt relative to the reference attitude. The tilt sensor 44 can be realized, for example, by an acceleration sensor or an IMU including an acceleration sensor.

[0046] FIG. 4 is a side view schematically illustrating an example of a multicopter 10 equipped with a distance measurement sensor 42. The distance measurement sensor 42 is attached to the airframe 4 of the multicopter 10 shown in FIG. 4 . In this example, the distance measurement sensor 42 is a laser sensor (e.g., a LiDAR sensor) that emits a light beam L1 vertically downward when the airframe is not tilted. The distance measurement sensor 42 may include a light source that emits the light beam L1, a photodetector that detects light that is reflected from the surface of an object and returns, and a processor that calculates the distance to the reflection point of the light beam L1. The processor may be configured to calculate the distance to a measurement point where the light beam L1 is reflected, using technology such as ToF (Time of Flight), and output a signal indicating the distance. Such a distance measurement sensor 42 may be disposed on the bottom of the airframe of the multicopter 10, as shown in FIG. 4 . Alternatively, the distance measurement sensor 42 may be disposed on the side of the airframe. Alternatively, when a work machine 200 is connected to the multicopter 10, the distance measurement sensor 42 may be attached to the bottom or side of the work machine 200 facing downward.

[0047] An imaging device 46 is also attached to the body of the multicopter 10 shown in Figure 4. The imaging device 46 is attached to the body of the multicopter 10 facing downward, captures an image of an area below the multicopter 10 including the ground, and outputs image data.

[0048] The control device 4a shown in FIG. 3 includes a processing device 34 and a storage device 37. The processing device 34 may be, for example, the companion computer described above, or a combination of a flight controller and a companion computer. The processing device 34 may be configured to execute arithmetic processing necessary for flight and attitude control of the multicopter 10, such as processing to calculate the rotational speed of each rotor. The processing device 34 may further be configured to execute processing to calculate the difference in altitude between the point at which the distance was measured and the aircraft, based on the distance measured by the ranging sensor 42 and the aircraft's tilt angle measured by the tilt sensor 44.

[0049] The storage device 37 stores data referenced by the processing device 34 during processing and data generated by the processing device 34. The storage device 37 stores, for example, map data of the area in which the multicopter 10 flies. The map data may include location information such as the latitude, longitude, and altitude of each point. The storage device 37 may be included inside the processing device 34 or may be a device independent of the control device 4a. For example, the storage device 37 may be storage connected to the multicopter 10 via a network (for example, on the cloud).

[0050] The control device 4a can adjust the rotational speed of each rotor to change the inclination angle of the multicopter 10, thereby moving the multicopter 10 in a desired direction. In this embodiment, the control device 4a can cause the distance measurement sensor 42 to measure distances while the airframe is tilted by controlling the rotation of each rotor. With the airframe tilted in this manner, the processing device 34 in the control device 4a can calculate the altitude difference between the point where the distance was measured (measurement point) and the airframe based on the distance measured by the distance measurement sensor 42 and the inclination angle of the airframe measured by the inclination sensor 44, and output information indicating this altitude difference to the storage device 37. When the ground is substantially parallel to the horizontal plane, the altitude difference between the measurement point and the airframe represents the distance from the ground to the airframe, i.e., the altitude of the airframe. Therefore, according to this embodiment, the altitude of the airframe, i.e., the distance from the ground, can be measured even when the airframe of the multicopter 10 is tilted (e.g., while moving). Furthermore, by measuring the distances to multiple points on the ground while continuously or intermittently changing the inclination angle of the aircraft, the control device 4a can determine the distribution of altitude differences between the multiple points and the aircraft based on the distance to each point and the inclination angle of the aircraft for each measurement. Based on the distribution of altitude differences, it is also possible to estimate the inclination angle on a slope.

[0051] 5 and 6 are diagrams illustrating the altitude estimation method of this embodiment. The arrows in FIGS. 5 and 6 schematically represent light beams emitted from the distance measurement sensor 42. In these examples, the multicopter 10 is flying above a substantially horizontal ground surface 90. Here, "flying" is not limited to horizontal movement but broadly includes ascending, descending, and hovering. In the example of FIG. 5, the multicopter 10 is not tilted and is in a hovering state. In the example of FIG. 6, the multicopter 10 is tilted at a tilt angle θ. Note that when the multicopter 10 is tilted, it moves in a certain direction (left in the example of FIG. 6) unless a strong headwind is blowing. However, if the distance measurement is performed in a sufficiently short time, the effect of the movement associated with the tilt of the aircraft on the distance measurement can be ignored.

[0052] As shown in Figure 5, when the airframe is not tilted (i.e., the tilt angle is 0 degrees), the distance measurement sensor 42 measures the distance from the airframe to a measurement point located vertically downward. If the measured distance is L and the altitude difference between the measurement point on the ground 90 and the airframe is H, then in the example of Figure 5, L = H. In this example, the altitude difference H represents the distance from the ground 90 to the airframe, i.e., the altitude of the airframe. Therefore, when the airframe is not tilted, the altitude of the multicopter 10 can be immediately determined from the distance L measured by the distance measurement sensor 42.

[0053] On the other hand, as shown in Figure 6, when the airframe is tilted by an angle θ from the reference state, the altitude difference H between the distance measurement point and the airframe is expressed as H = L cos θ. Therefore, the processing device 34 in the control device 4a can calculate the altitude difference H based on the calculation H = L cos θ. In this example, since the ground 90 is horizontal, the altitude difference H indicates the altitude of the airframe. Therefore, the altitude of the multicopter 10 can be determined by the above calculation. According to this embodiment, the altitude can be determined even when the airframe of the multicopter 10 is tilted. Therefore, there is no need to provide a mechanism such as a gimbal to maintain the attitude of the distance measurement sensor 42 in a constant attitude, which reduces costs.

[0054] In the examples of Figures 5 and 6, the ground 90 is parallel to the horizontal plane, but the ground may be inclined from the horizontal plane. For example, as shown in Figure 7, the ground 90 may include a slope 91. Figure 7 is a diagram schematically illustrating an example of distance measurement on a slope 91. In the example of Figure 7, the control device 4a causes the distance measurement sensor 42 to measure the distance to a measurement point on the slope 91 while the body of the multicopter 10 is tilted. Based on the measured distance L and the inclination angle θ of the body measured by the inclination sensor 44, the control device 4a can calculate the altitude difference H between the measurement point and the aircraft (i.e., the vertical distance) and the horizontal distance D between the measurement point and the aircraft.

[0055] The following relationships exist among the measurement distance L, the tilt angle θ, the altitude difference H between the measurement point and the aircraft, and the horizontal distance D between the measurement point and the aircraft: H=L cos θ (Equation 1) D=L sin θ (Equation 2)

[0056] The processing device 34 of the control device 4a can calculate the altitude difference H based on the calculation of Equation 1, and can calculate the horizontal distance D based on the calculation of Equation 2. The processing device 34 can be configured to generate information correlating the horizontal distance D with the altitude difference H and output the information to the storage device 37. This information represents the relative positional relationship between the multicopter 10 and the measurement point. The control device 4a generates such information each time the tilt angle of the aircraft is changed and records it in the storage device 37, thereby being able to calculate the tilt angle φ of the slope 91 from the information. This makes it possible to estimate the terrain.

[0057] FIG. 8 is a diagram illustrating the operation of estimating the inclination angle φ. The control device 4a can acquire information about the distance to multiple measurement points on the ground 90 below the aircraft by repeatedly changing the inclination angle θ of the aircraft and causing the distance measurement sensor 42 to measure the distance. In FIG. 8, seven of the multiple measurement points are illustrated by dotted circles. The control device 4a can calculate the altitude difference H between each of the multiple measurement points and the aircraft based on the distance L to each of the multiple measurement points and the inclination angle θ of the aircraft at each measurement. The control device 4a can estimate the inclination angle φ of the ground based on the altitude difference H between each of the multiple measurement points and the aircraft.

[0058] FIG. 8 shows an xyz coordinate system consisting of mutually orthogonal x-, y-, and z-axes. The operation of the multicopter 10 will be described below using this coordinate system. The x- and y-axes are parallel to the horizontal plane, and the z-axis is perpendicular to the horizontal plane. The vertically upward direction is the positive direction of the z-axis. The tilt of the aircraft is considered to be a rotational movement around a rotation axis parallel to the y-axis. The control device 4a can be configured to tilt the aircraft, for example, by aligning the rotation axis with the pitch axis or roll axis.

[0059] In the example of FIG. 8 , the control device 4a causes the distance measurement sensor 42 to repeatedly measure distances while continuously changing the inclination of the aircraft above the ground 90. In the example of FIG. 8 , the control device 4a continuously increases the inclination angle θ of the aircraft by decreasing the rotational speed of the multiple rotors located on the left side of the figure and increasing the rotational speed of the multiple rotors located on the right side of the figure. This causes the irradiation point (i.e., the measurement point) of the light beam emitted from the distance measurement sensor 42 to move diagonally upward along the surface of the slope 91, allowing continuous distance measurement to the multiple measurement points. The control device 4a may also change the inclination angle θ of the aircraft in the direction opposite to the direction shown in FIG. 8 . That is, the inclination of the aircraft may be changed by decreasing the inclination angle θ from a state in which the aircraft is significantly inclined (e.g., a state in which the aircraft is moving at high speed).

[0060] The above operation allows distance measurement of multiple points, similar to measurements using a scanning LiDAR, even if the distance measurement sensor 42 does not have a scanning function. The distance measurement sensor 42 can measure distances, for example, 10 to 1,000 times per second, or even more frequently. If the aircraft tilts, the multicopter 10 may move in one direction (left in the example of FIG. 8 ). However, if measurements are taken at sufficiently short intervals, the effect of the movement on the measurements can be ignored.

[0061] Each time a measurement is performed, the control device 4a calculates the altitude difference H and the horizontal distance D by calculating H = L cos θ (Equation 1) and D = L sin θ (Equation 2) based on the tilt angle θ measured by the tilt sensor 44 and the measured distance L, and stores the calculated values ​​in the storage device 37. If the influence of the movement of the multicopter 10 during measurement can be ignored, the control device 4a can determine the tilt angle φ of the slope 91 based on the values ​​of the altitude difference H and the horizontal distance D for each of the multiple measurement points. Specifically, the positions of the multiple measurement points in the xz plane shown in FIG. 8 can be approximated by a straight line using, for example, the least squares method, and the slope of the straight line can be determined as the tilt angle φ of the slope 91.

[0062] If the influence of the movement of the multicopter 10 on the measurement cannot be ignored, the control device 4a can record the position of the multicopter 10 each time a measurement is made and estimate the ground slope φ using the position information. The position (e.g., latitude, longitude, and altitude) of the multicopter 10 can be measured using a positioning device such as a GNSS receiver and an altimeter including a barometric pressure sensor. Based on the position of the multicopter 10 determined based on the outputs of these devices, the control device 4a calculates the aircraft's position coordinates (x ｂ , y ｂ , z ｂ 8, for simplicity, the position of the distance measurement sensor 42 is treated as the position of the aircraft. The position of the aircraft is not limited to the position of the distance measurement sensor 42, and may be another position such as the center of gravity of the aircraft.

[0063] The position coordinates of the measurement point are calculated using the altitude difference H and horizontal distance D between the measurement point and the aircraft, as follows: (x ｂ +D, y ｂ , z ｂ -H), where H and D are different for each measurement point. Based on the coordinate values ​​of each measurement point, the control device 4a can approximate the surface of the slope 91 with a straight line in the xz plane, and determine the inclination of that straight line as the slope angle φ of the slope 91.

[0064] 8, the control device 4a acquires distance information for the plurality of measurement points by changing the inclination of the aircraft, but other methods may be used. For example, if the distance measurement sensor 42 is a LiDAR sensor that emits a light beam in multiple directions and measures the distance to each of the plurality of measurement points irradiated with the light beam, the control device 4a can acquire distance information for the plurality of measurement points while fixing the inclination of the aircraft.

[0065] FIG. 9 is a schematic diagram illustrating the distance measurement operation performed by a multicopter 10 equipped with a LiDAR sensor 42A equipped with a beam scanning function that changes the emission direction of a light beam. In FIG. 9 , the straight arrows indicate examples of light beams emitted from the LiDAR sensor 42A, and the arc arrows indicate changes in the emission direction of the light beam. The LiDAR sensor 42A can change the emission direction of the light beam within a predetermined angular range (e.g., 90 degrees, 120 degrees, 150 degrees, etc.) below the multicopter 10. One cycle of measuring the distances of multiple measurement points by changing the emission direction of the light beam within this angular range is referred to as a scan. The LiDAR sensor 42A can be configured to perform scanning operations, for example, 10 or more times per second.

[0066] When such a LiDAR sensor 42A is used as the distance measurement sensor 42, the control device 4a can cause the LiDAR sensor 42A to measure distances to multiple points while maintaining a constant inclination of the multicopter 10's airframe. As a result, similar to the example shown in FIG. 8 , the control device 4a can calculate the altitude difference H and horizontal distance D based on the measured distance L for each of the multiple measurement points. In the example shown in FIG. 9 , the control device 4a can calculate the altitude difference H and horizontal distance D between each of the multiple measurement points and the aircraft based on the distance to each of the multiple measurement points measured by the LiDAR sensor 42A, the inclination angle of the aircraft at each measurement, and the emission angle of the light beam at each measurement. Here, the emission angle of the light beam refers to the angle between a reference direction (e.g., the direction of the center of the scan range) and the emission direction of the light beam. In the example shown in FIG. 9 , the control device 4a can also calculate the inclination φ of the slope based on the altitude difference H and horizontal distance D between each measurement point and the position of the aircraft at the time of measurement.

[0067] 9 , the control device 4a may cause the LiDAR sensor 42A to measure distances while the aircraft is hovering, for example, without tilting the aircraft. The LiDAR sensor 42A is not limited to the above-described scanning LiDAR sensor, but may also be a flash LiDAR sensor. A flash LiDAR sensor can acquire distance data from multiple measurement points at once.

[0068] Next, the operation of the control device 4a in this embodiment will be described in more detail with reference to Fig. 10. The following operation is executed by the processing device 34 in the control device 4a.

[0069] Fig. 10 is a flowchart showing a specific example of the operation of the control device 4a in the example shown in Fig. 8. The control device 4a starts the operation shown in Fig. 10 during the flight of the multicopter 10, for example, in response to an operation by a user using a control device or in accordance with a preset program.

[0070] In step S101, the control device 4a determines whether or not the ground is present within the measurable range below the multicopter 10 based on the image acquired by the imaging device 46. The control device 4a detects the ground from the image based on any image recognition algorithm, such as segmentation. If the ground is detected within the measurable range below the multicopter 10, the process proceeds to step S102. If the ground is not detected within the measurable range, the process executes the operation of step S101 again. The operation of step S101 is repeated until the ground is detected within the measurable range.

[0071] If the ground is not detected within the measurable range, the control device 4a may send a warning to an external computer (e.g., a terminal device used by the pilot or observer of the multicopter 10). This allows the pilot or observer to be notified if, for example, it is difficult to estimate the inclination of a slope because of overgrown trees or grass on the ground or the presence of a structure such as a building or vehicle on the ground. After sending the warning, the control device 4a may end the measurement operation without returning to step S101.

[0072] In step S102, the control device 4a adjusts the rotational speed of each rotor to set the inclination angle θ of the airframe to an initial value. The initial value may be any angle less than 90 degrees, such as 0 degrees, 10 degrees, or 20 degrees. After step S102, the process proceeds to step S103.

[0073] In step S103, the control device 4a sends a distance measurement command to the distance measurement sensor 42. In response to this command, the distance measurement sensor 42 emits a light beam to measure the distance. The control device 4a stores the measured distance in the storage device 37 in association with the aircraft's tilt angle and aircraft position (e.g., latitude, longitude, and altitude) at that time. After step S103, the process proceeds to step S104.

[0074] In step S104, the control device 4a determines whether or not measurements have been completed for all of the preset angles of the aircraft. If there are angles that have not yet been measured, the process proceeds to step S105. If measurements have been completed for all angles, the process proceeds to step S106.

[0075] In step S105, the control device 4a adjusts the rotation speed of each rotor to change the tilt angle of the airframe by a predetermined value. After step S105, the process returns to step S103.

[0076] The operations of steps S103, S104, and S105 are repeated until a Yes determination is made in step S104. Through these operations, distances from the aircraft to a plurality of measurement points located in different directions are measured and recorded.

[0077] In step S106, the control device 4a calculates the altitude difference H and horizontal distance D between each measurement point and the aircraft by performing the calculations of the above-mentioned equations (1) and (2) based on the measured distance of each measurement point and the inclination angle of the aircraft at each measurement. After step S106, the process proceeds to step S107.

[0078] In step S107, the control device 4a calculates the ground inclination angle φ based on the altitude difference H and horizontal distance D between each measurement point and the aircraft. For example, as described with reference to FIG. 8 , the control device 4a determines the position coordinates of each measurement point in the xz plane shown in FIG. 8 based on the altitude difference H and horizontal distance D between each measurement point and the aircraft, and the position of the aircraft at the time of each measurement. Next, the control device 4a approximates the slope of the ground with a straight line in the xz plane from the position coordinates of each measurement point, and calculates the slope as the ground inclination angle φ. The control device 4a records the calculated ground inclination angle φ in the storage device 37. Alternatively, the control device 4a may transmit information about the calculated ground inclination angle φ to an external computer.

[0079] By performing the above operations, the altitude differences between the aircraft and the multiple measurement points can be obtained, and the inclination angle φ of the slope can be calculated.

[0080] FIG. 11 is a flowchart showing an example of the operation of the control device 4a in the example shown in FIG. 9 . In this example, the distance measurement sensor 42 is a LiDAR sensor 42A that emits light beams in multiple directions to measure distances to multiple measurement points. Therefore, the operations of steps S102, S104, and S105 in FIG. 10 are omitted. In this example, when the control device 4a detects the ground within the distance measurement range in step S101, the control device 4a proceeds to step S103 and instructs the LiDAR sensor 42A to measure distances. In response to this instruction, the LiDAR sensor 42A performs a beam scan and measures the distance to each of the multiple measurement points. The control device 4a stores the measured distances in the storage device 37 in association with the aircraft's tilt angle at that time. The operations of the subsequent steps S106 and S107 are the same as those in the example shown in FIG. 10 .

[0081] Fig. 12 is a diagram schematically illustrating an example of control based on the altitude difference H between the measurement point and the airframe. In the example of Fig. 12, the airframe of the multicopter 10 is equipped with a coupling device 210 that suspends a work implement 200A that performs ground work. The work implement 200A is an agricultural machine that performs ground work such as mowing, sowing seeds, fertilizing, or pest control. The work implement 200A is suspended by a cable 220 extending from the coupling device 210. The multicopter 100 can fly with the work implement 200A suspended.

[0082] In this example, the control device 4a of the multicopter 10 adjusts the altitude of the airframe by controlling the rotation of the multiple rotors based on the distance between the airframe and the work unit 200A and the altitude difference H calculated using the above method. For example, as shown in FIG. 12 , if a slope 91 exists in the direction of movement of the work unit 200A suspended by the multicopter 10, the altitude of the airframe can be adjusted according to the altitude difference H to position the work unit 200A at an optimal height. This allows the work unit 200A to be maintained at an appropriate height, for example, when performing work on the slope 91, enabling smooth operation. Note that the coupling device 210 may have a function that allows it to include a mechanism for adjusting the altitude of the work unit 200A by winding or unwinding the cable 220. In this case, the control device 4a may adjust the altitude of the work unit 200A by having the coupling device 210 adjust the length of the cable 220, instead of adjusting the altitude of the multicopter 10.

[0083] After calculating the altitude difference H, the processing device 34 may transmit the information to a flight control device such as a flight controller or an external device (for example, a mobile terminal, a personal computer, or a cloud server). When the altitude difference H is transmitted to the external device, the external device may display information based on the altitude difference H on a display device. By displaying such information, the user can remotely visually confirm the flight or operation of the multicopter 10.

[0084] The control device 4a in the embodiment of the present disclosure can be realized by a digital computer system programmed to execute the above-described processes.

[0085] 13 is a block diagram showing an example of the hardware configuration of the control device 4a. The control device 4a includes a processing device 34, a read-only memory (ROM) 35, a random access memory (RAM) 36, a storage device 37, and a communication I / F 38. These components are connected to each other via a bus 39.

[0086] The processing device 34 is a device including one or more semiconductor integrated circuits (e.g., processors). The processor is also called a central processing unit (CPU) or a microprocessor. The processor sequentially executes computer programs stored in the ROM 35 to perform the above-described processing. The term "processor" is broadly interpreted as including a field programmable gate array (FPGA), a graphic processor unit (GPU), an application specific integrated circuit (ASIC), or an application specific standard product (ASSP) equipped with a CPU.

[0087] The ROM 35 is, for example, a writable memory (e.g., a PROM), a rewritable memory (e.g., a flash memory), or a read-only memory. The ROM 35 stores a program that controls the operation of the processor. The ROM 35 does not have to be a single recording medium, but may be a collection of multiple recording media. Some of the collection of multiple recording media may be removable memories.

[0088] The RAM 36 provides a working area for temporarily loading the programs stored in the ROM 35 at boot time. The RAM 36 does not have to be a single recording medium, but can be a collection of multiple recording media.

[0089] The communication I / F 38 is an interface for communication between the control device 4a and other electronic components or electronic control units (ECUs). For example, the communication I / F 38 can perform wired communication in accordance with various protocols. The communication I / F 38 may perform wireless communication in accordance with the Bluetooth (registered trademark) standard and / or the Wi-Fi (registered trademark) standard. Both standards include wireless communication standards using frequencies in the 2.4 GHz band.

[0090] The storage device 37 may be, for example, a semiconductor memory, a magnetic storage device, an optical storage device, or a combination thereof. The storage device 37 may store, for example, map data useful for the autonomous flight of the multicopter 10 and various sensor data acquired by the multicopter 10 during flight.

[0091] As described above, the control device 4a may include, for example, a flight control device such as a flight controller and a host computer (companion computer). The companion computer may execute the above-described processes and issue flight-related commands based on the results of those processes to the flight controller.

[0092] Furthermore, the altitude estimation process performed by the processing device 34 of the control device 4a in the above-described embodiment may be executed by an external processing device (e.g., a mobile terminal, a personal computer, or a cloud server) that communicates with the multicopter 10. In this case, the distance data acquired by the ranging sensor 42 and the tilt angle data acquired by the tilt sensor 44 are transmitted to the external processing device via the communication device 4c. The external processing device acquires the transmitted distance data and tilt angle data, calculates the altitude difference between the distance measurement point and the aircraft based on the data, and outputs information indicating the altitude difference to the storage device. The processing device may transmit the information indicating the altitude difference to the multicopter 10. The control device 4a of the multicopter 10 may execute control, such as adjusting the altitude of the multicopter 10 or the work machine 200, based on the altitude difference between the distance measurement point and the aircraft calculated by the external processing device.

[0093] 14 is a schematic diagram showing an example configuration of a system including a multicopter 10. Some or all of the functions of the control device 4a or the processing device 34 may be implemented by one or more servers (computers) 500 or terminal devices (including portable and fixed types) 600 connected to the communication device 4c of the multicopter 10 via a communication network N. An agricultural machine 700 such as a tractor may be connected to such a communication network N, and communication may be performed between the multicopter 10 and the agricultural machine 700. Some of the data used for processing by the control device 4a and control signals for the multicopter 10 may be provided from the agricultural machine 700 to the multicopter 10 via the communication network N.

[0094] This specification discloses the solutions described in the following items.

[0095] [Item 1] An unmanned aerial vehicle comprising: an airframe having multiple rotors; a ranging sensor attached facing downward to the airframe; an inclination sensor that measures the inclination angle of the airframe; and a control device, wherein the control device, while tilting the airframe by controlling the rotation of the multiple rotors, calculates the difference in altitude between the distance measurement point and the airframe based on the distance measured by the ranging sensor and the inclination angle measured by the inclination sensor, and outputs information indicating the difference in altitude.

[0096] [Item 2] The distance sensor is positioned to measure the distance from the aircraft to a measurement point located vertically downward when the aircraft is not tilted, and when the measured value of the distance is L, the measured value of the tilt angle is θ, and the altitude difference is H, the control device calculates the altitude difference H based on the calculation H = L cos θ.

[0097] [Item 3] When the horizontal distance between the aircraft and the distance measurement point is D, the control device calculates the horizontal distance D based on the calculation D = L sin θ, and outputs information relating the horizontal distance D to the altitude difference H. An unmanned aerial vehicle as described in Item 2.

[0098] [Item 4] The control device of any one of items 1 to 3 acquires distance information from multiple measurement points on the ground below the aircraft by repeatedly changing the inclination angle of the aircraft and having the ranging sensor measure distances, and calculates the altitude difference between each of the multiple measurement points and the aircraft based on the distance information from the multiple measurement points and the inclination angle of the aircraft for each measurement.

[0099] [Item 5] The unmanned aerial vehicle according to Item 4, wherein the control device calculates and outputs the inclination angle of the ground based on the difference in altitude between each of the plurality of measurement points and the aircraft.

[0100] [Item 6] An unmanned aerial vehicle described in any one of items 1 to 3, wherein the ranging sensor is a LiDAR sensor that emits a light beam in multiple directions and measures the distance to each of multiple measurement points irradiated by the light beam, and the control device calculates the altitude difference between each of the multiple measurement points and the aircraft based on the distance to each of the multiple measurement points measured by the LiDAR sensor, the inclination angle of the aircraft at each measurement, and the emission angle of the light beam at each measurement.

[0101] [Item 7] The unmanned aerial vehicle according to Item 6, wherein the control device calculates and outputs the inclination angle of the ground based on the altitude difference between each of the plurality of measurement points and the aircraft.

[0102] [Item 8] An unmanned aerial vehicle described in any one of Items 4 to 7, further comprising an imaging device attached facing downwardly of the aircraft, wherein the control device causes the ranging sensor to acquire distance information for the multiple measurement points when a slope is detected from an image acquired by the imaging device.

[0103] [Item 9] An unmanned aerial vehicle described in any one of Items 1 to 8, wherein the airframe is equipped with a coupling device for suspending a work machine that performs ground work, and the control device adjusts the altitude of the airframe by controlling the rotation of the multiple rotors based on the distance between the airframe and the work machine and the calculated altitude difference.

[0104] [Item 10] A sensing system comprising: a ranging sensor attached facing downward to the body of an unmanned aerial vehicle; an inclination sensor that measures the inclination angle of the body; and a processing device, wherein the processing device calculates the difference in altitude between the distance measurement point and the body based on the distance measured by the ranging sensor when the body is inclined and the inclination angle measured by the inclination sensor when measuring the distance, and outputs information indicating the difference in altitude.

[0105] [Item 11] A sensing method using an unmanned aerial vehicle having an aircraft, a ranging sensor attached facing downward to the aircraft, and an inclination sensor that measures the inclination angle of the aircraft, the sensing method including: acquiring distance data measured by the ranging sensor when the aircraft is inclined; acquiring inclination angle data measured by the inclination sensor when measuring the distance; calculating the altitude difference between the distance measurement point and the aircraft based on the distance data and the inclination angle data, and outputting information indicating the altitude difference.

[0106] The unmanned aerial vehicle disclosed herein can be widely used not only for aerial photography, surveying, logistics, and pesticide spraying, but also for ground work related to agricultural work, transporting harvested products and agricultural materials, and the like.

[0107] 2...Rotor (propeller), 3...Rotational drive device, 4...Airframe body, 4a...Control device, 4b...Sensor group, 4c...Communication device, 5...Airframe frame, 10...Multicopter, 12...Rotor, 14...Motor, 16...ESC, 22...Rotor, 34...Processing device, 37...Storage device, 42...Distance measurement sensor, 44...Inclination sensor, 46, Imaging device, 52...Battery, 200...Work machine, 210...Coupling device, 220...Cable, 300...Sensing system

Claims

1. an airframe having multiple rotors; a distance measurement sensor attached to the airframe facing downward; an inclination sensor that measures the inclination angle of the aircraft; a control device; Equipped with the control device, while tilting the airframe by controlling the rotation of the plurality of rotors, calculates an altitude difference between the distance measurement point and the airframe based on the distance measured by the distance measurement sensor and the tilt angle measured by the tilt sensor, and outputs information indicating the altitude difference. unmanned aircraft.

2. the distance measurement sensor is arranged to measure a distance from the airframe to a measurement point located vertically downward when the airframe is not tilted; When the measured value of the distance is L, the measured value of the tilt angle is θ, and the difference in altitude is H, The control device calculates the altitude difference H based on an operation of H = L cos θ. The unmanned aerial vehicle according to claim 1 .

3. When the horizontal distance between the aircraft and the distance measurement point is D, The control device Calculating the horizontal distance D based on the equation D=L sin θ, outputting information relating the horizontal distance D and the altitude difference H; The unmanned aerial vehicle according to claim 2.

4. The control device By repeating the operation of measuring distances with the distance measuring sensor multiple times while changing the tilt angle of the aircraft, distance information is obtained from multiple measurement points on the ground below the aircraft; calculating an altitude difference between each of the plurality of measurement points and the aircraft based on distance information of the plurality of measurement points and the inclination angle of the aircraft at each measurement; An unmanned aerial vehicle according to any one of claims 1 to 3.

5. The unmanned aerial vehicle according to claim 4 , wherein the control device calculates and outputs the inclination angle of the ground based on the difference in altitude between each of the plurality of measurement points and the aircraft.

6. the distance measurement sensor is a LiDAR sensor that emits light beams in multiple directions and measures distances to each of multiple measurement points irradiated with the light beams, The control device calculates an altitude difference between each of the plurality of measurement points and the aircraft based on the distance to each of the plurality of measurement points measured by the LiDAR sensor, the inclination angle of the aircraft at each measurement, and the emission angle of the light beam at each measurement. An unmanned aerial vehicle according to any one of claims 1 to 3.

7. The unmanned aerial vehicle according to claim 6 , wherein the control device calculates and outputs the inclination angle of the ground based on the difference in altitude between each of the plurality of measurement points and the aircraft.

8. Further, an imaging device is attached facing downward of the airframe, The unmanned aerial vehicle according to claim 4 , wherein the control device causes the distance measuring sensor to acquire distance information of the plurality of measurement points when a slope is detected from the image acquired by the imaging device.

9. The vehicle body is provided with a coupling device for suspending a work machine for performing ground work, the control device adjusts the altitude of the airframe by controlling the rotation of the plurality of rotors based on the distance between the airframe and the work machine and the calculated altitude difference. An unmanned aerial vehicle according to any one of claims 1 to 3.

10. a ranging sensor attached facing downward to a body of the unmanned aerial vehicle; an inclination sensor that measures the inclination angle of the aircraft; a processing device; Equipped with the processing device calculates an altitude difference between the measurement point of the distance and the aircraft based on the distance measured by the distance measurement sensor when the aircraft is tilted and the tilt angle measured by the tilt sensor when measuring the distance, and outputs information indicating the altitude difference. Sensing system.

11. A sensing method using an unmanned aerial vehicle including an airframe, a distance measurement sensor attached to the airframe facing downward, and an inclination sensor that measures an inclination angle of the airframe, acquiring distance data measured by the distance measuring sensor while the aircraft is tilted; acquiring data of the tilt angle measured by the tilt sensor when measuring the distance; calculating an altitude difference between the distance measurement point and the aircraft based on the distance data and the tilt angle data, and outputting information indicating the altitude difference; A sensing method comprising: