Unmanned aircraft, and method for controlling unmanned aircraft

Abstract

This unmanned aircraft comprises a plurality of rotors, a rotational drive device of a first type that drives one or more first rotors included in the plurality of rotors, a rotational drive device of a second type that drives one or more second rotors included in the plurality of rotors, and a control device that controls the rotation of the plurality of rotors by controlling the rotational drive device of a first type and the rotational drive device of a second type. The control device makes the difference between a first thrust, which is the sum of the thrusts generated by the one or more first rotors, and a second thrust, which is the sum of the thrusts generated by the one or more second rotors, smaller when a landing operation is performed than when hovering.

Description

Unmanned aerial vehicle and method for controlling unmanned aerial vehicle

[0001] The present disclosure relates to unmanned aerial vehicles and methods for controlling unmanned aerial vehicles.

[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] Patent Document 2 describes an unmanned aerial vehicle (autonomous flying device) that can increase the payload and continuous flight time and can accurately adjust its position and attitude during flight.

[0005] JP 2022-104737 A JP 2019-59362 A

[0006] The maximum payload and flight time of unmanned aerial vehicles are insufficient for some applications, and further improvements are required.

[0007] The present disclosure provides unmanned aerial vehicles suitable for agricultural applications that allow for increased payload and / or flight time.

[0008] In an exemplary and non-limiting embodiment, the unmanned aerial vehicle of the present disclosure comprises a plurality of rotors, a first type of rotational drive device that drives one or more first rotors included in the plurality of rotors, a second type of rotational drive device that drives one or more second rotors included in the plurality of rotors, and a control device that controls the rotation of the plurality of rotors by controlling the first type of rotational drive device and the second type of rotational drive device, and when performing a landing operation, the control device reduces the difference between a first thrust, which is the sum of the thrusts generated by the one or more first rotors, and a second thrust, which is the sum of the thrusts generated by the one or more second rotors, to be smaller than when hovering.

[0009] In an exemplary and non-limiting embodiment, the control method for an unmanned aerial vehicle of the present disclosure is a control method for an unmanned aerial vehicle having multiple rotors, and includes controlling the rotation of the multiple rotors by controlling a first type of rotational drive device that drives one or more first rotors included in the multiple rotors and a second type of rotational drive device that drives one or more second rotors included in the multiple rotors, and when performing a landing operation, making the difference between a first thrust that is the sum of the thrusts generated by the one or more first rotors and a second thrust that is the sum of the thrusts generated by the one or more second rotors smaller than when hovering.

[0010] According to embodiments of the unmanned aerial vehicle and the control method for the unmanned aerial vehicle of the present disclosure, it is possible to realize an unmanned aerial vehicle that is suitable for agricultural use and that can increase the payload and / or flight time.

[0011] 1 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. 2 is a plan view schematically showing one basic configuration example of an unmanned aerial vehicle having multiple rotors. FIG. 3 is a side view schematically showing one basic configuration example of an unmanned aerial vehicle having multiple rotors. FIG. 4 is a plan view schematically showing another basic configuration example of an unmanned aerial vehicle having multiple rotors. FIG. 5 is a block diagram showing an example basic configuration of a battery-powered multicopter. FIG. 6 is a block diagram showing an example basic configuration example of a series hybrid multicopter. FIG. 7 is a block diagram showing an example basic configuration example of a parallel hybrid multicopter. FIG. 8 is a top view schematically showing a multicopter according to an exemplary embodiment. FIG. 9 is a side view schematically showing a multicopter according to an exemplary embodiment. FIG. 10 is a block diagram showing an example system configuration of a multicopter according to an exemplary embodiment. FIG. 11 is a graph showing an example of time change in the total thrust generated by the main rotors and the total thrust generated by the sub-rotors. FIG. 12 is a graph showing an example of time change in the total thrust generated by the main rotors and the total thrust generated by the sub-rotors. It is a flowchart showing an example of processing performed by a control device. It is a block diagram showing an example of a system configuration in a multicopter of an exemplary embodiment. It is a block diagram showing an example of a hardware configuration of a control device. It is a diagram showing a schematic example of a communication network to which a multicopter is connected.

[0012] 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."

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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."

[0018] 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.

[0019] 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."

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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).

[0024] 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.

[0025] The battery 52 is a secondary battery that stores power by charging and supplies power to the motors 14 by discharging. The battery 52 and the multiple motors 14 operate to rotate the multiple rotors 2, making it possible to generate a desired thrust.

[0026] Each of the multiple rotors 2 generally has multiple blades with a fixed pitch angle and generates thrust by 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 a rotating rotor 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 a relatively larger diameter may be referred to as the "main rotor," and the rotor 2 with a relatively smaller diameter may be referred to as the "sub-rotor." Note that, regardless of the diameter, the configuration of the rotary drive device 3 may include a rotor 2 capable of generating a relatively larger thrust and a rotor 2 with a relatively smaller thrust. In this case, the rotor 2 capable of generating a relatively larger thrust may be referred to as the "main rotor," and the rotor 2 with a relatively smaller thrust may be referred to as the "sub-rotor." For example, the rotor 2 that generates a relatively large thrust per rotation may be referred to as the "main rotor," and the rotor 2 that generates a relatively small thrust per rotation may be referred to as the "sub-rotor." In one example, the main rotor may be positioned more inward than the sub-rotors. In other words, each rotor 2 may be positioned so that the distance from the center of the airframe to the rotation axis of each main rotor is shorter than the distance from the center of the airframe to the rotation axis of each sub-rotor.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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."

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] FIG. 2A is a block diagram illustrating an example of the basic configuration of a battery-powered multicopter 10. The battery-powered multicopter 10 includes multiple rotors 12, multiple motors 14 for rotating the rotors 12, multiple ESCs (electric speed controllers) 16 each having a motor drive circuit for driving the motors 14, a battery 52 for supplying power to the corresponding motors 14 via each ESC 16, a control device 4a for controlling 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 illustrates 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. The ESC 16 may be included in the control device 4a.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Below, an example of the configuration and operation of an unmanned aerial vehicle according to an embodiment of the present disclosure will be described, taking a multicopter that uses parallel hybrid drive as an example.

[0042] <Basic Configuration> Fig. 3A is a schematic top view of the multicopter 100 according to this embodiment, and Fig. 3B is a side view thereof. Fig. 3B illustrates a work implement 200 coupled to the multicopter 100. In addition to or instead of the work implement 200, luggage, agricultural materials, other machinery, or containers, cases, or packages capable of accommodating these items may be coupled to the multicopter 100. Hereinafter, the weight of the work implement 200 and the work implement itself may be referred to as the "payload." The "coupling" between the multicopter 100 and the work implement 200 or the like may be performed using various tools or devices.

[0043] The multicopter 100 shown in FIG. 3A includes eight sub-rotors 12 and two main rotors 22. Each sub-rotor 12 is composed of four sets of propellers 12a and 12b that rotate coaxially and in opposite directions. Each of the propellers 12a and 12b has two blades. The propellers 12a and 12b are rotated by a motor 14. The four sets of propellers 12a and 12b that rotate coaxially and in opposite directions are located at the vertices of a square. The main rotor 22 is composed of two propellers 22a that rotate in opposite directions at different positions. Each propeller 22a has four blades. The eight propellers 12a and 12b of the sub-rotor 12 have the same pitch angle and diameter. The two propellers 22a of the main rotor 22 also have the same pitch angle and diameter. The diameter of the propeller 22a is 1.2 times or more, for example, 1.4 times or more and 2.0 times or less, the diameter of the propellers 12a and 12b.

[0044] The multicopter 100 includes an airframe 110 having four arms 110A for the sub-rotors 12 and two arms 110B for the main rotors 22. The airframe frame 110 supports an airframe main body 120 that includes various electronic and mechanical components, which will be described later. The airframe main body 120 and the airframe frame 110 may be collectively referred to as an "airframe 121."

[0045] In the example of FIG. 3B , the airframe main body 120 has a power supply device 76 and an actuator 78 used for coupling to the work machine 200, etc. The power supply device 76 is a device that supplies power generated within the airframe main body 120 to the work machine 200. The actuator 78 is a device such as an electric motor that performs an operation to couple the work machine 200 to the airframe main body 120 of the multicopter 100. In the example of FIG. 3B , the actuator 78 drives a mechanism that winds up a cable connecting the airframe main body 120 and the work machine 200. This cable may include a power supply line for supplying power from the multicopter 100 to the work machine 200, and a communication line for communication between the multicopter 100 and the work machine 200.

[0046] <System Configuration> FIG. 4 is a block diagram showing an example of a system configuration of the multicopter 100 according to this embodiment.

[0047] In the illustrated example, the airframe 120 of the multicopter 100 has a control device 30 including a flight controller 32, a sensor group 72, and a communication device 74. These are basically the same as the control device 4a, the sensor group 4b, and the communication device 4c of the airframe 4 of the multicopter 10 described with reference to FIG. 1A.

[0048] The multicopter 100 of this embodiment includes eight sub-rotors 12, eight motors 14 for rotating the eight sub-rotors 12, and eight ESCs for controlling the eight motors 14. Each ESC 16 receives a signal (motor control signal) for controlling the motor 14 from the control device 30 via a wiring 82. The motor control signal is, for example, a PWM (Pulse With Modulation) signal. When the motor control signal is a PWM signal, the duty cycle of the PWM signal can indicate an analog value of the motor rotation speed. Each ESC 16 controls the rotation speed of the motor 14 connected to that ESC 16 based on the motor control signal from the control device 30. While FIG. 4 illustrates one set of "sub-rotors 12, motors 14, and ESCs 16" for simplicity, the multicopter 100 of this embodiment includes eight sets of "sub-rotors 12, motors 14, and ESCs 16." The number of these sets is not limited to eight.

[0049] The control device 30 is connected to each of the ESCs 16 via electrically independent wiring 82, and can individually control each of the eight ESCs 16. As described above, the sub-rotors 12 are used not only to generate lift but also for attitude control. Attitude control is achieved by the flight controller 32 of the control device 30 obtaining measured or estimated values ​​indicating the attitude of the airframe 120 from the sensors 72, determining the current attitude of the airframe 120, and controlling the rotational speed of each of the motors 14 in accordance with the difference from the target attitude.

[0050] The aircraft body 120 includes a main rotor drive unit 24 that drives the main rotor 22 and a main rotor control unit 26 that controls the main rotor drive unit 24. In this embodiment, the main rotor drive unit 24 is an internal combustion engine. Therefore, the main rotor control unit 26 includes an engine control unit (ECU). The main rotor control unit 26 acquires sensor data such as the accelerator opening, intake air temperature, engine speed, and temperatures of various components of the main rotor drive unit 24, which is an internal combustion engine, and controls the internal combustion engine. The main rotor control unit 26 is connected to the control device 30 via wiring 82, such as a CAN (Controller Area Network) bus. The main rotor control unit 26 is configured to output an engine control signal based on a signal transmitted from the control device 30. The engine control signal includes, for example, a throttle opening. A digital-to-analog converter (DAC) and / or a voltage converter may be connected between the control device 30 and the main rotor control unit 26. A mechanical device such as a clutch and a reducer may be provided between the main rotor drive section 24 and the main rotor 22.

[0051] The main rotor drive unit 24 is preferably an internal combustion engine with little vibration. In this embodiment, the main rotor drive unit 24 is, for example, an opposed-piston engine. Opposed-piston engines are disclosed, for example, in Japanese Patent No. 5508604. The entire contents of Japanese Patent No. 5508604 are incorporated herein by reference.

[0052] The main rotor drive unit 24, which is an internal combustion engine, can generate electricity by driving a power generator 42, such as an alternator. In this embodiment, the power generator 42 has the structure of an AC synchronous motor having a rotor and a stator. Therefore, when the main rotor drive unit 24 is started, the power generator 42 can also function as a "starter" by rotating the rotor when current is applied. The power generator 42 rectifies the AC generated by power generation and converts it into DC. The power generator 42 generates DC power required to drive the motor 14 and supplies it to each ESC 16 via wiring 80. The power generator 42 is configured to output a DC voltage of, for example, 250 V or higher. Note that the wiring 80 is a power wiring, and the wiring 82 is a signal wiring. Each of the wirings 80 and 82 includes multiple conductors.

[0053] The power generation device 42 is connected to a power management device 44. The power management device 44 is connected to the control device 30 and a battery management device 54, which will be described later. The power management device 44 can control the amount of power generated by the power generation device 42 based on signals from the control device 30 or the battery management device 54. This amount of power generation can be variably controlled by the power management device 44 in accordance with the power required by the motor 14 and the battery 52, even when the engine speed of the main rotor drive unit 24, which is an internal combustion engine, is constant.

[0054] The aircraft body 120 further includes a battery 52 in the form of a plurality of cells, for example, lithium ion secondary batteries, connected in series or in parallel, and a battery management device 54 that controls the charging and discharging of the battery 52 .

[0055] The battery 52 receives DC power from the power generation device 42 via a power switch 56 and can be charged by the power. The operation of the power switch 56 can be controlled by a battery management unit 54 and the control device 30. The battery management unit 54 is a device that measures or estimates parameter values ​​that define the state of the battery 52, such as the current flowing through the battery 52, cell voltage, cell balance, state of charge (SOC), state of health (SOH), and temperature.

[0056] The battery management unit 54 can control the power switch 56 depending on the state of the battery 52. ​​For example, when the battery 52 is in a state requiring charging, the battery management unit 54 electrically connects the power generation device 42 and the battery 52 using the power switch 56, and supplies power from the power generation device 42 to the battery 52 to perform a charging operation. At this time, the battery management unit 54 controls the power management unit 44 to increase the amount of power generated by the power generation device 42 so that the power supplied to the ESC 16 does not drop below a desired level. On the other hand, when the battery 52 is in a state requiring no charging, the battery management unit 54 disconnects the electrical connection between the power generation device 42 and the battery 52 using the power switch 56, and stops charging the battery 52.

[0057] In this embodiment, the battery 52 has a storage capacity that allows the aircraft to continue to fly to a location where landing is possible and land there, by continuing to generate lift and control attitude using the sub-rotor 12, even if power generation by the power generation device 42 stops for some reason and lift from the main rotor 22 is lost. In other words, when the multicopter 100 of this embodiment is flying normally, the power required to drive the sub-rotor 12 can be supplied to the ESC 16 from the power generation device 42, rather than from the battery 52. ​​Therefore, even if the payload and flight time are increased, there is little need to increase the storage capacity of the battery 52 accordingly.

[0058] The power stored in the battery 52 can be output as a DC voltage of, for example, 250 V or higher. However, this DC voltage decreases as the charging rate decreases. Therefore, when the charging rate falls below a predetermined level, the battery management device 54 operates to supply part of the DC power from the power generation device 42 to the battery 52 to charge the battery 52.

[0059] The battery 52 is connected to a power circuit board 60. The power circuit board 60 has a function of stepping down the voltage output from the battery 52 to, for example, 24 V, 12 V, or 5 V. The DC voltage output from the battery 52 is converted to a desired voltage by the power circuit board 60 and then supplied to other electronic components. In the example of FIG. 4 , the power stepped down by the power circuit board 60 is supplied to the control device 30 and the actuator 78 via wiring 80.

[0060] 4 , the power supply device 76 is electrically connected to the power generation device 42 or the battery 52 by a power switch 56. The power supply device 76 in this example is configured to supply power generated within the machine body 120 to an external machine or device such as a work machine 200.

[0061] The airframe main body 120 may have a configuration not shown in FIG. 4 . For example, the airframe main body 120 may include a fuel tank that stores fuel necessary for the operation of the main rotor drive unit 24, a water-cooling or air-cooling device for cooling the main rotor drive unit 24, and electrical components such as lighting devices and an electric pump. The electrical components can be operated by power that has been stepped down to a predetermined voltage by the power circuit board 60. A battery for the electrical components (auxiliary battery) may be provided and configured to supply power to the electrical components. Such an auxiliary battery may be charged by the battery 52 or the power generation device 42.

[0062] In this embodiment, the motor 14 functions as a plurality of "attitude control devices" that respectively drive a plurality of first rotors (sub-rotors) 12. In addition, the main rotor drive unit 24, which is an internal combustion engine, functions as a "main thrust generating device" that drives the second rotor (main rotor) 22.

[0063] In the example shown in FIG. 4, the control device 30 and the main rotor control unit 26 are separate components, but a single control device (computer or ECU) may have the functions of the control device 30 and the main rotor control unit 26.

[0064] In this embodiment, the control device 30 can change the ratio (thrust ratio) between the first thrust of the sub-rotor (first rotor) obtained from the multiple motors 14 and the second thrust of the main rotor (second rotor) obtained from the main rotor drive unit 24. This point will be described in detail below.

[0065] Generally, the responsiveness of the motor 14 is superior to that of an internal combustion engine. If the time from when a torque command signal is input until the torque required to rotate the rotors 12, 22 reaches a target torque value is called the "response time," the response time of the motor is, for example, approximately 1 / 100 of the response time of the internal combustion engine. Therefore, to control the attitude of the multicopter 100, it is desirable to detect the difference between the current and target attitude angles of the multicopter 100 and control the rotational speed of each of the multiple sub-rotors 12 with a high response speed so as to reduce this difference. An increase in rotor rotational speed results in an increase in thrust. By adjusting the thrust of each of the multiple sub-rotors 12, the attitude of the multicopter 100 can be controlled quickly and with high precision.

[0066] On the other hand, an internal combustion engine can efficiently generate large thrust. The sub-rotor 12 is rotated using electric power generated by the power of the main rotor drive unit 24, which is an internal combustion engine, but energy loss occurs when converting mechanical energy into electrical energy. Therefore, from the perspective of improving energy consumption efficiency, it is preferable that the main rotor drive unit 24 be used to rotate the main rotor 22 and generate the main thrust. Furthermore, to increase the thrust of the main rotor 22, it is preferable that the diameter of the main rotor 22 be larger than the diameter of each of the multiple sub-rotors 12.

[0067] However, when the main rotor 22, which generates the main thrust, generates a large thrust, the large thrust and rotational moment may actually inhibit the attitude control function of the sub-rotor 12. As a result, even if multiple sub-rotors 12 are rotated using multiple motors 14 with excellent response, a delay in response may occur in attitude control. On the other hand, if the rotation speed of the main rotor 22 is reduced, attitude control performance improves, but energy consumption efficiency decreases.

[0068] Battery-powered multicopters use various algorithms to adjust the torque of each of the multiple motors to regulate the thrust of each rotor and control it to a desired attitude. When performing attitude control using such multiple motors, adding a rotor rotated by an internal combustion engine can complicate the calculations required for attitude control. To avoid this complexity, it is effective to fix the "ratio" of the thrust obtained from the multiple motors to the thrust obtained from the internal combustion engine. For this reason, conventional parallel hybrid types have adopted a control method that fixes this ratio.

[0069] However, as a result of studies by the inventors, it has been found that when using the multicopter 100 for agricultural work, for example, it is preferable to make the above-mentioned "ratio" variable rather than fixed, compared to when flying the multicopter 100 for simple logistics or surveillance purposes. This is because when flying the multicopter 100 for agricultural purposes, it flies under a variety of different conditions, such as various agricultural tasks (ground tasks) within a field, traveling between multiple fields, and transporting agricultural materials or harvested crops. The level of response speed required for attitude control varies greatly depending on these conditions. Furthermore, when various types of implements with different weights and shapes are appropriately selected and connected depending on the type of agricultural work, the required lift and attitude control accuracy can also vary greatly.

[0070] In this embodiment, when precise attitude control is not required, for example, when there is little external disturbance such as wind and the payload is small, or when only movement is required without performing work using the work equipment, the thrust of the main rotor 22 can be increased and the thrust of the sub-rotor 12 can be reduced instead.

[0071] On the other hand, when precise attitude control is required, for example, when performing ground work while flying with a work machine coupled, or when it is required to move the aircraft body more agilely to change attitude than in normal flight, it is preferable to reduce (or eliminate) the thrust of the main rotor 22 and instead increase the thrust of the sub-rotor 12. Reducing the thrust of the main rotor in this way results in an overall decrease in energy consumption efficiency, but makes it possible to improve attitude control performance (response performance).

[0072] <Landing Control> An example of control when the multicopter 100 of this embodiment performs a landing operation (sometimes referred to as "landing control") will be described. When performing a landing operation, the control device 30 of the multicopter 100 of this embodiment controls the second thrust T ２ and a first thrust T which is the sum of the thrusts generated by the sub-rotor (first rotor) 12. １ The difference between the attitude of the aircraft and the ground is made smaller than that during hovering. "When performing a landing operation" refers to, for example, the period from when a signal instructing landing is received until landing. The multicopter 100 of this embodiment can improve the accuracy of attitude control during a landing operation.

[0073] 5A, 5B, and 5C show the second thrust T ２ and a first thrust T which is the sum of the thrusts generated by the sub-rotor 12. １ 5A and 5B , the second thrust T ２ and first thrust T １ During the flight of the multicopter 100, the ratio is set to a preferred value (for example, T ２ : T １ The second thrust T ２ and first thrust T １Fixing the ratio between the second thrust T and the second thrust T can avoid the control from becoming complicated, but on the other hand, the accuracy of the attitude control may be insufficient in certain flight states or situations. ２ and first thrust T １ If the ratio is fixed to the same value as before the landing operation (for example, during hovering), the multicopter 100 may rotate in the yaw direction.

[0074] One possible reason for insufficient attitude control accuracy during landing is the difference in response speed between the main rotor 22 and the sub-rotor 12. If the main rotor 22 and the sub-rotor 12 are driven by different rotary drive devices, the response speeds of the main rotor 22 and the sub-rotor 12 may differ. The rotary drive device that drives the sub-rotor (first rotor) 12 is sometimes referred to as the "first type rotary drive device," and the rotary drive device that drives the main rotor (second rotor) 22 is sometimes referred to as the "second type rotary drive device." The unmanned aerial vehicle according to this embodiment is equipped with the rotary drive device 3D shown in FIG. 1A . That is, the main rotor 22 is driven by an internal combustion engine (second type rotary drive device), and the sub-rotor 12 is driven by a motor 14 (first type rotary drive device). Generally, the response speed of the motor 14 is superior to that of an internal combustion engine, so the response speed of the main rotor 22 is slower than that of the sub-rotor 12. When the main rotor 22 generates a large thrust, the large thrust and rotational moment may actually inhibit the attitude control effect of the sub-rotor 12. As a result, even if multiple sub-rotors 12 are rotated using multiple motors 14 with excellent responsiveness, a delay in the response of the attitude control may occur.

[0075] Even if the rotary drive device 3D shown in FIG. 1A is replaced with the rotary drive device 3A, 3B, or 3C shown in FIG. 1A, an unmanned aerial vehicle having a first rotor and a second rotor driven by different rotary drive devices can be realized by differentiating some of the motors 14 or power transmission systems 23 from the other motors 14 or power transmission systems 23. In such a case, the motor 14 or power transmission system 23 with a relatively high response speed can be the "first type of rotary drive device," and the motor 14 or power transmission system 23 with a relatively low response speed can be the "second type of rotary drive device." The unmanned aerial vehicle may also be equipped with multiple internal combustion engines with different response speeds. In this case, the internal combustion engine with a relatively high response speed can be the "first type of rotary drive device," and the internal combustion engine with a relatively low response speed can be the "second type of rotary drive device." This can realize an unmanned aerial vehicle having a first rotor and a second rotor driven by different rotary drive devices. For example, the output of an internal combustion engine with a relatively high response speed is lower than the output of an internal combustion engine with a relatively low response speed.

[0076] The difference in the response speed of the first rotor 12 and the response speed of the second rotor 22 is not limited to when the rotors are driven by different rotary drive devices. For example, the difference may occur when the thrust generated per rotation of the first rotor 12 and the second rotor 22 differs, or when the inertial forces of the first rotor 12 and the second rotor 22 differ due to, for example, differences in weight between the first rotor 12 and the second rotor 22. This embodiment can also be applied to such cases. That is, for example, when performing a landing operation, the control device 30 reduces the difference between the first thrust, which is the sum of the thrust generated by the first rotor, and the second thrust, which is the sum of the thrust generated by the second rotor, which generates a greater thrust per rotation than the first rotor, to a value smaller than that during hovering. Alternatively, when performing a landing operation, the control device 30 reduces the difference between the first thrust, which is the sum of the thrust generated by the first rotor, and the second thrust, which is the sum of the thrust generated by the second rotor, which generates a greater inertial force than the first rotor, to a value smaller than that during hovering.

[0077] The control device 30 in this embodiment calculates a second thrust T ２ and a first thrust T which is the sum of the thrusts generated by the sub-rotor 12. １ For example, as shown in the example of FIG. 5C , when performing a landing operation, the control device 30 sets the second thrust T ２ First thrust T １ The ratio (T １ / T ２ ) is made larger than when hovering, and then the first thrust T １ and second thrust T ２ Decrease the second thrust T ２ First thrust T １ The ratio (T １ / T ２ ) is larger than that during hovering, the attitude control performance (response performance) can be improved. Typically, during hovering, the first thrust T １ is the second thrust T generated by the main rotor 22 for generating the main thrust. ２ Therefore, when performing landing operation, the control device 30 controls the first thrust T １ and / or by increasing the second thrust T ２ By reducing the second thrust T ２ First thrust T １ The ratio (T １ / T ２ ) can be made larger than when hovering.

[0078] An example of landing control will be described with reference to Figures 6 and 7. Figure 6 is a flowchart showing an example of processing performed by the control device 30. Figure 7 is a schematic diagram for explaining an example of a system configuration for realizing landing control. Parts common to the system configuration example shown in Figure 4 may not be shown or described.

[0079] First, in step S200, the control device 30 determines whether or not to start landing control. The control device 30 determines whether or not to start landing control based on, for example, a signal commanding landing from an external device such as a piloted aircraft or a remote monitoring device used by a user, or a preset flight plan. If it is determined that landing control should be started ("Yes"), the process proceeds to step S202.

[0080] In step S202, the control device 30 reduces the rotational speed of the main rotor 22. The control device 30 reduces the rotational speed of the main rotor 22 by controlling the main rotor drive unit 24, which is an internal combustion engine. The control device 30 controls the main rotor drive unit 24, which is an internal combustion engine, via the main rotor control unit 26 by sending a control signal (e.g., a PWM signal for the main rotor 22) from the flight controller 32 to the main rotor control unit 26. When the communication device 74 receives a signal instructing landing, the control device 30 causes the communication device 74 to send a signal to the main rotor control unit 26 to reduce the rotational speed of the main rotor 22 (or a signal to reduce the engine speed). The main rotor control unit 26 outputs an engine control signal to the main rotor drive unit 24 based on the PWM signal for the main rotor 22 and the signal from the communication device 74.

[0081] After step S202, in step S204, the control device 30 increases the rotational speed of the sub-rotor 12. Each ESC 16 receives a signal for controlling the motor 14 (e.g., a PWM signal for the sub-rotor 12) from the flight controller 32 of the control device 30. Since the responsiveness of the motor 14 is generally superior to that of an internal combustion engine, it is preferable to decrease the rotational speed of the main rotor 22 in step S202, and then increase the rotational speed of the sub-rotor 12 in step S204.

[0082] In step S206, the control device 30 calculates the second thrust T ２ First thrust T １ The ratio (T １ / T ２) is greater than a predetermined value. The predetermined value is, for example, ２ First thrust T １ The ratio of the second thrust T ２ First thrust T １ The ratio (T １ / T ２ Steps S202 and S204 are repeated until it is determined that the second thrust T ２ First thrust T １ The ratio (T １ / T ２ If it is determined that the difference (%) is greater than the predetermined value (if "Yes"), the process proceeds to step S208.

[0083] In step S208, the control device 30 reduces the rotation speed of the main rotor 22 and the rotation speed of the sub-rotor 12. At this time, the second thrust T ２ First thrust T １ The ratio (T １ / T ２ ) may be maintained, the rotational speed of the main rotor 22 and the rotational speed of the sub-rotor 12 may be reduced. After that, when the multicopter 100 lands, the landing control is ended.

[0084] The process shown in FIG. 6 can be repeatedly executed by, for example, the flight controller 32 of the control device 30 while the multicopter 10 is flying.

[0085] The control method of this embodiment can be applied not only to landing operations but also to flight conditions and situations requiring improved attitude control accuracy (responsiveness). For example, when taking off, when there is external disturbance such as wind, when the wind is strong (high wind speed), when changing the flight path to avoid an obstacle, when attaching or suspending a load such as luggage to the aircraft body, or when there is a delay or deviation in attitude control responsiveness, the accuracy (responsiveness) of attitude control can be improved by relatively reducing the thrust generated by the rotor with a relatively low response speed and relatively increasing the thrust generated by the rotor with a relatively high response speed. In this case, the timing for reducing the thrust generated by the rotor with a relatively low response speed (e.g., reducing the engine speed) may precede the timing for increasing the thrust generated by the rotor with a relatively high response speed. Furthermore, the acceleration / deceleration rate for reducing the thrust generated by the rotor with a relatively low response speed may be set higher than the acceleration / deceleration rate for increasing the thrust generated by the rotor with a relatively high response speed.

[0086] 8 is a block diagram showing an example of the hardware configuration of the control device 30. The control device 30 includes a processor 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.

[0087] The processor 34 is one or more semiconductor integrated circuits, and is also referred to as a central processing unit (CPU) or a microprocessor. The processor 34 sequentially executes computer programs stored in the ROM 35 to perform the above-described processing. The term "processor 34" is broadly interpreted as including a field programmable gate array (FPGA) equipped with a CPU, a graphic processor unit (GPU), an application specific integrated circuit (ASIC), or an application specific standard product (ASSP).

[0088] 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.

[0089] 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.

[0090] The communication I / F 38 is an interface for communication between the control device 30 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 also 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 that use frequencies in the 2.4 GHz band.

[0091] 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.

[0092] As described above, the control device 30 may include, for example, a flight control device such as the flight controller 32 and a higher-level computer (companion computer) as separate components. Also, a system including the control device 30 and the main rotor control unit 26 may be used as the "control device."

[0093] 9 , some or all of the functions of the control device 30 may be implemented by one or more servers (computers) 500 or terminal devices (including portable and fixed types) 400 connected to the communication device 74 of the multicopter 100 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 100 and the agricultural machine 700. Some of the data used for processing by the control device 30 and control signals for the multicopter 100 may be provided from the agricultural machine 700 to the multicopter 100 via the communication network N.

[0094] This specification discloses an unmanned aerial vehicle and a control method described in the following items.

[0095] [Item 1] An unmanned aerial vehicle comprising: a plurality of rotors; a first type rotational drive device that drives one or more first rotors included in the plurality of rotors; a second type rotational drive device that drives one or more second rotors included in the plurality of rotors; and a control device that controls the rotation of the plurality of rotors by controlling the first type rotational drive device and the second type rotational drive device, wherein, when performing a landing operation, the control device reduces the difference between a first thrust that is the sum of the thrusts generated by the one or more first rotors and a second thrust that is the sum of the thrusts generated by the one or more second rotors to be smaller than when hovering.

[0096] [Item 2] The unmanned aerial vehicle described in Item 1, wherein the control device, when performing a landing operation, increases the ratio of the first thrust to the second thrust compared to when hovering, and then reduces the first thrust and the second thrust.

[0097] [Item 3] The unmanned aerial vehicle according to item 1 or 2, wherein the control device makes the first thrust smaller than the second thrust during hovering.

[0098] [Item 4] An unmanned aerial vehicle described in any one of items 1 to 3, wherein the control device, when performing a landing operation, increases the first thrust to make the ratio of the first thrust to the second thrust greater than when hovering, and then decreases the first thrust and the second thrust.

[0099] [Item 5] An unmanned aerial vehicle described in any one of items 1 to 3, wherein the control device, when performing a landing operation, reduces the second thrust to make the ratio of the first thrust to the second thrust greater than when hovering, and then reduces the first thrust and the second thrust.

[0100] [Item 6] An unmanned aerial vehicle described in any one of items 1 to 3, wherein the control device, when performing a landing operation, increases the first thrust and decreases the second thrust, thereby making the ratio of the first thrust to the second thrust greater than when hovering, and then decreases the first thrust and the second thrust.

[0101] [Item 7] The unmanned aerial vehicle described in any one of Items 1 to 6, wherein the control device controls the second type of rotary drive device to reduce the rotational speed of the one or more second rotors when a signal instructing landing is received.

[0102] [Item 8] An unmanned aerial vehicle described in any one of Items 1 to 6, wherein the one or more first rotors are a plurality of first rotors, the first type of rotational drive device includes a plurality of electric motors that respectively drive the plurality of first rotors, and the second type of rotational drive device is an internal combustion engine.

[0103] [Item 9] The unmanned aerial vehicle described in Item 8, wherein the control device, when receiving a signal instructing landing, reduces the rotational speed of the one or more second rotors by reducing the rotational speed of the second type of rotary drive device.

[0104] [Item 10] An unmanned aerial vehicle according to any one of items 1 to 9, wherein the diameter of the one or more second rotors is larger than the diameter of the one or more first rotors.

[0105] [Item 11] An unmanned aerial vehicle described in any one of items 1 to 10, wherein the one or more second rotors are used to generate thrust, and the one or more first rotors are used to generate thrust and control attitude.

[0106] [Item 12] The unmanned aerial vehicle described in any one of Items 1 to 11, wherein the one or more second rotors generate a greater thrust per rotation than the one or more first rotors.

[0107] [Item 13] An unmanned aerial vehicle according to any one of items 1 to 12, wherein the one or more second rotors have a total thrust that can be generated that is greater than that of the one or more first rotors.

[0108] [Item 14] An unmanned aerial vehicle described in any one of items 1 to 13, wherein the distance from the center of the body of the unmanned aerial vehicle to the rotation axis of each of the one or more second rotors is shorter than the distance from the center of the body to the rotation axis of each of the one or more first rotors.

[0109] [Item 15] An unmanned aerial vehicle described in any one of Items 1 to 14, wherein the inertial force of the one or more second rotors is greater than the inertial force of the one or more first rotors.

[0110] [Item 16] A control method for an unmanned aerial vehicle having multiple rotors, the control method including: controlling the rotation of the multiple rotors by controlling a first type of rotational drive device that drives one or more first rotors included in the multiple rotors, and a second type of rotational drive device that drives one or more second rotors included in the multiple rotors; and when performing a landing operation, making the difference between a first thrust that is the sum of the thrusts generated by the one or more first rotors and a second thrust that is the sum of the thrusts generated by the one or more second rotors smaller than when hovering.

[0111] [Item 17] The control method according to Item 16, further comprising, when performing a landing operation, increasing a ratio of the first thrust to the second thrust to be greater than that during hovering, and then reducing the first thrust and the second thrust.

[0112] [Item 18] The unmanned aerial vehicle described in any one of Items 1 to 15, wherein the one or more first rotors have a higher response speed than the one or more second rotors.

[0113] [Item 19] An unmanned aerial vehicle comprising a plurality of rotors and a control device that controls the rotation of the plurality of rotors, wherein the plurality of rotors include one or more first rotors and one or more second rotors that generate a thrust per rotation greater than that of the one or more first rotors, and wherein the control device, when performing a landing operation, makes the difference between a first thrust that is the sum of the thrusts generated by the one or more first rotors and a second thrust that is the sum of the thrusts generated by the one or more second rotors smaller than when hovering.

[0114] [Item 20] An unmanned aerial vehicle comprising a plurality of rotors and a control device that controls the rotation of the plurality of rotors, wherein the plurality of rotors include one or more first rotors and one or more second rotors having a greater inertial force than the one or more first rotors, and wherein the control device, when performing a landing operation, makes the difference between a first thrust that is the sum of the thrusts generated by the one or more first rotors and a second thrust that is the sum of the thrusts generated by the one or more second rotors smaller than when hovering.

[0115] 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.

[0116] 2: Rotor (propeller), 3: Rotation drive device, 4: Airframe body, 4a: Control device, 4b: Sensor group, 4c: Communication device, 5: Airframe frame, 10: Multicopter, 12: Sub-rotor, 14: Motor, 16: ESC, 22: Main rotor, 52: Battery, 54: Battery management device

Claims

1. A plurality of rotors; a first type of rotation drive device that drives one or more first rotors included in the plurality of rotors; a second type of rotation drive device that drives one or more second rotors included in the plurality of rotors; a control device that controls the first type rotation drive device and the second type rotation drive device to control rotation of the plurality of rotors; Equipped with The control device, when performing a landing operation, reduces the difference between the first thrust, which is the sum of the thrust generated by the one or more first rotors, and the second thrust, which is the sum of the thrust generated by the one or more second rotors, compared to when hovering.

2. 2. The unmanned aerial vehicle according to claim 1, wherein the control device, when performing a landing operation, increases the ratio of the first thrust to the second thrust compared to when hovering, and then reduces the first thrust and the second thrust.

3. The control device The unmanned aerial vehicle according to claim 1 , wherein the first thrust is smaller than the second thrust during hovering.

4. The control device An unmanned aerial vehicle described in any one of claims 1 to 3, wherein when performing a landing operation, the first thrust is increased so that the ratio of the first thrust to the second thrust is greater than when hovering, and then the first thrust and the second thrust are reduced.

5. The control device An unmanned aerial vehicle described in any one of claims 1 to 3, wherein when performing a landing operation, the second thrust is reduced to make the ratio of the first thrust to the second thrust greater than when hovering, and then the first thrust and the second thrust are reduced.

6. The control device An unmanned aerial vehicle as described in any one of claims 1 to 3, wherein when performing a landing operation, the first thrust is increased and the second thrust is decreased, thereby making the ratio of the first thrust to the second thrust greater than when hovering, and then the first thrust and the second thrust are decreased.

7. 4. An unmanned aerial vehicle as described in any one of claims 1 to 3, wherein the control device controls the second type of rotary drive device to reduce the rotational speed of the one or more second rotors when it receives a signal instructing landing.

8. the one or more first rotors are a plurality of first rotors, the first type rotation drive device includes a plurality of electric motors that drive the plurality of first rotors, respectively; The unmanned aerial vehicle according to claim 1 , wherein the second type of rotary drive device is an internal combustion engine.

9. 9. The unmanned aerial vehicle of claim 8, wherein the control device, when receiving a signal instructing landing, reduces the rotational speed of the one or more second rotors by reducing the rotational speed of the second type of rotary drive device.

10. The unmanned aerial vehicle of claim 1 , wherein the diameter of the one or more second rotors is greater than the diameter of the one or more first rotors.

11. the one or more second rotors are used to generate thrust; The unmanned aerial vehicle according to claim 1 , wherein the one or more first rotors are used for thrust generation and attitude control.

12. An unmanned aerial vehicle as described in any one of claims 1 to 3, wherein the one or more second rotors generate a greater thrust per rotation than the one or more first rotors.

13. An unmanned aerial vehicle as described in any one of claims 1 to 3, wherein the one or more second rotors have a total thrust that can be generated that is greater than that of the one or more first rotors.

14. An unmanned aerial vehicle described in any one of claims 1 to 3, wherein the distance from the center of the body of the unmanned aerial vehicle to the rotation axis of each of the one or more second rotors is shorter than the distance from the center of the body to the rotation axis of each of the one or more first rotors.

15. The unmanned aerial vehicle according to claim 1 , wherein the inertial force of the one or more second rotors is greater than the inertial force of the one or more first rotors.

16. 1. A method for controlling an unmanned aerial vehicle having multiple rotors, comprising: controlling rotation of the plurality of rotors by controlling a first type rotation drive device that drives one or more first rotors included in the plurality of rotors and a second type rotation drive device that drives one or more second rotors included in the plurality of rotors; When performing a landing operation, a difference between a first thrust that is a total of thrusts generated by the one or more first rotors and a second thrust that is a total of thrusts generated by the one or more second rotors is made smaller than that during hovering; A control method comprising:

17. 17. The control method according to claim 16, further comprising: when performing a landing operation, increasing a ratio of the first thrust to the second thrust to be greater than that during hovering, and then reducing the first thrust and the second thrust.