Unmanned aircraft and control method therefor

Abstract

This unmanned aircraft includes a plurality of rotors and comprises a plurality of orientation control devices that each drive one of a plurality of first rotors included in the plurality of rotors, a main thrust generation device that drives at least one second rotor included in the plurality of rotors, and a control device that controls the flight of the unmanned aircraft. The control device changes the ratio between first thrust outputted from the plurality of orientation control devices and second thrust outputted from the main thrust generation device.

Description

Unmanned aerial vehicle and control method thereof

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

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

[0006] The present disclosure provides an unmanned aerial vehicle and a control method thereof that can increase payload and / or flight time.

[0007] In an exemplary and non-limiting embodiment, the unmanned aerial vehicle of the present disclosure comprises a plurality of rotors, a plurality of attitude control devices that respectively drive a plurality of first rotors included in the plurality of rotors, a main thrust generating device that drives at least one second rotor included in the plurality of rotors, and a control device that controls the flight of the unmanned aerial vehicle and changes the ratio of the second thrust output from the main thrust generating device to the first thrust output from the plurality of attitude control devices.

[0008] In an exemplary and non-limiting embodiment, the control method for an unmanned aerial vehicle of the present disclosure includes an unmanned aerial vehicle having a plurality of electric motors that respectively drive a plurality of first rotors included in the plurality of rotors, and an internal combustion engine that drives at least one second rotor included in the plurality of rotors, and changes the ratio of the second thrust of the at least one second rotor to the first thrust of the plurality of first rotors.

[0009] According to an embodiment of the unmanned aerial vehicle and its control method disclosed herein, when precise attitude control is required, it is possible to reduce the thrust of a rotor with a relatively slow response speed and increase the thrust of a rotor with a relatively fast response speed.

[0010] 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 of a series hybrid multicopter. FIG. 7 is a block diagram showing an example basic configuration of a parallel hybrid multicopter. FIG. 8 is a top view schematically showing a multicopter in an embodiment of the present disclosure. FIG. 9 is a side view schematically showing a multicopter in the present embodiment. FIG. 10 is a block diagram showing an example system configuration of a multicopter in the present embodiment. FIG. 11 is a plan view schematically showing a flight path of a multicopter in the present embodiment. FIG. 12 is a diagram for explaining an overview of an agricultural management system in the present embodiment. FIG. 13 is a diagram showing an example of a work plan for each agricultural work. FIG. 14 is a diagram showing an example of a setting screen displayed on a terminal device. FIG. 15 is a flowchart showing an example of an algorithm for changing the ratio of the second thrust of the main rotor to the first thrust of the sub-rotor in the present embodiment. 1 is a flowchart illustrating another example of an algorithm for changing the ratio of the second thrust of the main rotor to the first thrust of the sub-rotor in the present embodiment. 2 is a block diagram illustrating an example of a hardware configuration of a control device in the present embodiment. 3 is a diagram illustrating an example of a communication network to which a multicopter is connected in the present embodiment.

[0011] 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."

[0012] There are various configurations of the rotary drive unit included in a multicopter. Figure 1A is a block diagram schematically illustrating four examples of the rotary drive unit 3 in this disclosure.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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."

[0017] 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.

[0018] 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."

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] 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.

[0024] 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.

[0025] 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."

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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."

[0030] 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.

[0031] 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.

[0032] 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. By connecting various ground implements (hereinafter 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.

[0033] 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 also 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 the materials, the work implement 200 can also transport agricultural materials or harvested products over a wide area.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] <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.

[0042] 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.

[0043] 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 110 supports an airframe body 120 including various electronic and mechanical components, which will be described later.

[0044] 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.

[0045] <System Configuration> FIG. 4 is a block diagram showing an example of a system configuration of the multicopter 100 according to this embodiment.

[0046] 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, sensor group 4b, and communication device 4c that the airframe 4 of the multicopter 10 has, as described with reference to FIG. 1A.

[0047] 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.

[0048] 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.

[0049] 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 position, 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 position. 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 reducer may be provided between the main rotor drive section 24 and the main rotor 22.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 .

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] In this embodiment, the control device 30 can change the ratio (= second thrust / first thrust: thrust ratio) of the main rotor thrust (second thrust) obtained from the main rotor drive unit 24 to the total thrust (first thrust) of the sub-rotors obtained from the multiple motors 14. This point will be described in detail below.

[0063] 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.

[0064] 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. However, energy loss occurs when converting mechanical energy into electrical energy. Therefore, from the viewpoint 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 first rotors 12.

[0065] 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.

[0066] 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 using multiple motors for attitude control, 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 (thrust ratio)" of the thrust obtained from the internal combustion engine to the thrust obtained from the multiple motors. For this reason, conventional parallel hybrids have adopted a control method that fixes this thrust ratio.

[0067] 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 "thrust 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 precision can also vary greatly.

[0068] Note that thrust (strictly speaking, "static thrust") is proportional to the square of the rotational speed multiplied by the pitch, assuming the propeller diameter is the same. Therefore, the "thrust ratio" can be changed by changing the ratio of the sum of the squares of the rotational speeds of one or more main rotors 22 to the sum of the squares of the rotational speeds of the sub-rotors 12. Strictly speaking, when attitude control is being performed, each of the multiple sub-rotors 12 may rotate at a different rotational speed, and therefore the total thrust of the multiple sub-rotors 12 may fluctuate over a short time scale. The "thrust ratio" in this disclosure can be changed over a time scale (e.g., 5 seconds or more, 10 seconds or more, preferably 20 seconds or more) that exceeds the change due to fluctuations associated with such attitude control. In other words, the thrust ratio can be defined based on the average thrust value over a time scale of 5, 10, or 20 seconds.

[0069] 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.

[0070] On the other hand, when precise attitude control is required, 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 enables improved attitude control performance (response performance). Examples of situations where precise attitude control is required include when performing ground work (agricultural work) while flying the multicopter 100 coupled with a work machine, and when the aircraft body is required to move more nimbly to change attitude than in normal flight. For example, when performing agricultural work while the multicopter 100 meanders over a field, precise control of the position, altitude, and attitude is required with respect to the field or the crops in the field. Furthermore, even when the multicopter 100 is stationary or flying along a linear path while performing agricultural work, if the wind is strong or the wind direction changes frequently, the multicopter 100 is required to precisely control its position, altitude, and attitude against such wind forces. Thus, multicopters 100 used for agricultural work often require precise attitude control, unlike multicopters used for logistics that move along a predetermined route from a starting point to a destination, and multicopters used for aerial photography or surveying of wide areas on the ground from the sky.

[0071] FIG. 5 is a plan view schematically illustrating flight paths P1, P2, P3, P4, P5, and P6 of the multicopter 100 according to this embodiment. The flight path P1 is a regularly meandering path, allowing the multicopter 100 to fly over a field F1 while performing tasks such as spraying fertilizer or pesticides. By controlling the position, altitude, and attitude of the multicopter 100 with high precision, it is possible to perform necessary tasks (ground operations) on the field F1, such as areas where crops exist or on the ground itself. To perform such operations, the flight altitude along the flight path P1 can be controlled to a preferred level, for example, within a range of 0.1 m to 5 m. Thus, during ground operations, the multicopter 100 moves along a predetermined path while performing precise attitude control.

[0072] When working in a farm field (work area) F1, the control device 30 of the multicopter 100 reduces the second thrust of the main rotor 22 and increases the first thrust of the multiple sub-rotors 12 compared to when moving between farm fields. As described above, reducing the ratio of the second thrust to the first thrust reduces the energy consumption efficiency of the multicopter 100. However, when performing precise work while fine-tuning the attitude of the multicopter 100, it is preferable to prioritize improving the responsiveness of attitude control over energy consumption efficiency. Note that even when working in the farm field F1, it is not necessary to always maintain a state in which the second thrust of the main rotor 22 is reduced and the first thrust of the sub-rotors 12 is increased. For example, depending on the type of work, such as lifting harvested crops, the second thrust of the main rotor 22 may be increased and the first thrust of the sub-rotors 12 may be decreased.

[0073] After completing work in the field F1, the multicopter 100 travels to area A1 via flight path P2. For simplicity, the flight distance P2 is depicted as short in the figure, but the actual length of flight path P2 may be, for example, several hundred meters or longer. The flight altitude of the multicopter 100 traveling along flight path P2 is, for example, between 30 meters and 150 meters. At this time, the control device 30 of the multicopter 100 increases the second thrust of the main rotor 22 and decreases the first thrust of the sub-rotor 12 compared to when working in the field F1. As a result, the total thrust can be efficiently increased, enabling high-speed travel.

[0074] It should be noted that while traveling along flight path P2, it is not necessary to constantly maintain a state in which the second thrust of the main rotor 22 is increased and the first thrust of the sub-rotor 12 is decreased. For example, if a strong wind blows and the attitude changes significantly while traveling along flight path P2, the second thrust of the main rotor 22 may be decreased and the first thrust of the sub-rotor 12 may be increased.

[0075] In area A1, the multicopter 100 can, for example, descend and land to receive agricultural supplies. When descending and landing, in order to precisely control the attitude of the multicopter 100, it is preferable that the control device 30 of the multicopter 100 decrease the second thrust of the main rotor 22 and increase the first thrust of the sub-rotor 12 compared to when traveling along flight path P2.

[0076] The multicopter 100 takes off from area A1 and heads toward the sky above area A2 via flight path P3. While traveling along flight path P3, the control device 30 of the multicopter 100 increases the second thrust of the main rotor 22 and decreases the first thrust of the sub-rotor 12. Upon reaching area A2, the multicopter 100 descends, lands, waits, and takes off. During descent, landing, and takeoff, the control device 30 of the multicopter 100 precisely controls attitude, as it did in area A1, and thus may decrease the second thrust of the main rotor 22 and increase the first thrust of the sub-rotor 12 compared to when traveling along flight path P3. The multicopter 100 then heads toward field F2 via flight path P4. After arriving at field F2, the multicopter 100 performs ground operations along flight path P5. In the farm field F2, the multicopter 100 performing ground work moves along a predetermined path while performing precise attitude control. When the multicopter 100 works in the farm field (work area) F2, the control device 30 reduces the second thrust of the main rotor 22 and increases the first thrust of the sub-rotor 12 compared to when moving between farm fields.

[0077] In this way, by dynamically or adaptively changing the ratio of the second thrust of the main rotor 22 to the first thrust of the sub-rotor 12 inside and outside a specific predetermined area (e.g., a work area such as a farm field), it becomes possible to optimize the operation of the parallel hybrid multicopter 100 according to a variety of situations.

[0078] As described above, an example of a situation in which it is preferable to relatively increase the thrust used for attitude control operations is a windy state. The higher the wind speed, the more difficult attitude control becomes, and it is therefore preferable to relatively increase the first thrust of the sub-rotor 12.

[0079] The situation in which it is preferable to relatively increase the first thrust of the sub-rotor 12 in this manner can be determined based on the type of work and / or weather conditions. Note that, for example, when strong winds are predicted based on weather information such as a weather forecast, or before starting various types of work such as ground work rather than simple movement, the thrust of the main rotor 22 may be reduced in advance. Conversely, when weaker winds are predicted, or before the end of work, the thrust of the main rotor 22 may be increased. By performing such "advance predictive control," it becomes possible to compensate for the relatively low responsiveness of the main rotor 22.

[0080] From the viewpoint of response speed, it is preferable that the timing for increasing or decreasing the thrust of the main rotor 22 precedes the timing for increasing or decreasing the thrust of the sub-rotor 12. Furthermore, from the viewpoint of preventing a sudden increase in the total value of energy consumption, it is preferable to decrease one thrust and then increase the other thrust.

[0081] As described above, in order for the multicopter 100 to appropriately change the thrust ratio depending on the work content, it is desirable for the control device 30 of the multicopter 100 to acquire information regarding a work plan that defines the work content. This information may include, for example, information specifying the work content, scheduled start time, and scheduled end time to be performed in the fields F1 and F2 in Figure 5, information regarding waypoints that define the flight paths P1 to P5, scheduled arrival times at areas A1 and A2, waiting times, and scheduled departure times. The creation of such a work plan that defines the work content is described below.

[0082] An example of a work plan that defines the work content of the multicopter 100 (and the work implement 200) will be described in detail below. In this embodiment, the work plan can be created by a management system (agricultural management system) for the multicopter 100.

[0083] FIG. 6 is a diagram illustrating an example of an agricultural management system that can be used in this embodiment. The agricultural management system illustrated in FIG. 6 includes multiple multicopters 100 and a management device 600. FIG. 6 also illustrates multiple terminal devices 400 used by multiple users. The management device 600 is a computer managed by a business operator that operates the agricultural management system. The multicopters 100, the terminal devices 400, and the management device 600 can communicate with each other via a communication network N. While FIG. 6 illustrates three multicopters 100, the agricultural management system may include two or fewer multicopters 100 or four or more multicopters 100. The agricultural management system may include not only multicopters 100 but also multiple different types of agricultural machinery, such as tractors, rice transplanters, and combine harvesters. Each multicopter 100 can perform its assigned agricultural work in a designated field according to instructions from the management device 600. In addition, the operation of the multicopter 100 may be performed by a user (operator) from the ground, in which case the management device 600 can be used by the user or other people to create work plans.

[0084] The agricultural management system shown in FIG. 6 can be suitably used for managing agricultural work using multiple multicopters 100 that fly automatically or manually. The management device 600 may create a work plan for each multicopter 100 based on information indicating a general plan for agricultural work input by each user using their respective terminal device 400, and may plan paths for each multicopter 100 based on the work plan. The management device 600 may be a collection of multiple computers. For example, the management device 600 may include a computer that creates a work plan for each multicopter 100 and a computer that plans paths for each multicopter 100.

[0085] The management device 600 determines the route along which each multicopter 100 should travel so that each multicopter 100 performs a predetermined agricultural task (e.g., tilling, sowing, planting, pest control, fertilizing, harvesting, etc.). The management device 600 references a map of the area in which each multicopter 100 will travel, generates a route on the map along which each multicopter 100 should travel, and transmits the route information to the terminal device 400 of each multicopter 100 or the user. Multicopters 100 capable of autonomous flight travel based on the received route information and perform the predetermined agricultural task in the field assigned to each multicopter 100. In the case of a manually flown multicopter 100, the user can operate the multicopter 100 based on the route information received by the terminal device 400.

[0086] The multicopter 100 in this embodiment can be equipped with or towed by a work implement 200, and therefore the multicopter 100 can fly over a field while performing agricultural work according to the type of work implement 200. The multicopter 100 can also move between fields or fly between a storage facility and a field.

[0087] In a preferred embodiment, the multicopter 100 has an automatic flight function. That is, the multicopter 100 can fly not only manually but also through the operation of the control device 30. In a preferred embodiment, the multicopter 100 can fly not only over the field but also outside the field automatically or remotely.

[0088] The control device 30 of the multicopter 100 in this embodiment can also automatically fly the multicopter 100 based on the position of the multicopter 100 and information about the target route generated by the management device 600. In addition to controlling the flight of the multicopter 100, the control device 30 can also control the operation of the work implement 200. This allows the multicopter 100 to perform agricultural work using the work implement 200 while automatically flying within a field. During flight, the multicopter 100 flies while generating a local route along the target route that can avoid obstacles based on sensor data output from a group of sensors 72, such as an imaging device or a LiDAR sensor.

[0089] The management device 600 may be, for example, a server computer that centrally manages information about farm fields and agricultural work on the cloud and supports agriculture by utilizing data on the cloud. The management device 600 may, for example, create a work plan for each multicopters 100 and perform global path planning for each multicopters 100 in accordance with the work plan.

[0090] The management device 600 generates a target route in the field based on information about the field. For example, the management device 600 can generate a target route in the field based on various information such as the pre-registered outline of the field, the area of ​​the field, the location of the entrance and exit to the field, the size of the multicopter 100, the model or size of the work implement 200, the type of work, the type of crop being cultivated, the crop growing area, the crop growth status, or the spacing between crop rows or furrows. The management device 600 can generate a target route in the field based on, for example, information input by a user using the terminal device 400 or another device. The management device 600 generates a route in the field so as to cover, for example, the entire work area where work is to be performed.

[0091] The terminal device 400 is a computer used by a user located remotely from the multicopter 100. The terminal device 400 may be a mobile terminal such as a laptop computer, smartphone, or tablet computer as shown in FIG. 6, or a stationary computer such as a desktop personal computer (PC). The terminal device 400 displays a setting screen on its display, allowing the user to input information necessary to create a work plan (e.g., a schedule for each agricultural task). When the user inputs the necessary information on the setting screen and performs a send operation, the terminal device 400 transmits the input information to the management device 600. The management device 600 creates a work plan based on that information. The terminal device 400 may also be used to register one or more fields where the multicopter 100 will perform agricultural tasks.

[0092] FIG. 7 is a diagram illustrating an example of a work plan for each multicopter 100. In this example, the work plan includes, for each registered multicopter 100, information indicating the date and time of the agricultural work, the field, the work content, and the agricultural implement 200 to be used. The work plan is not limited to the format shown in FIG. 7 and may include other information related to the work. For example, the work plan may include information such as the type and amount of pesticide or fertilizer to be applied. Based on this work plan, the processor included in the management device 600 generates a route for each multicopter 100 for each work day and issues instructions for the agricultural work to each multicopter 100. The work plan may be downloaded by the control device 30 of the multicopter 100 and stored in the storage device 37 (described later). In this case, the control device 30 may autonomously start operation according to the schedule indicated by the work plan stored in the storage device 37.

[0093] The management device 600 may create a work plan based not only on information indicating the approximate timing of agricultural work, but also on information input by each user using the terminal device 400. For example, the management device 600 may create a work plan based on information indicating a rough plan for each type of agricultural work in one or more fields managed by each user.

[0094] Fig. 8 is a diagram showing an example of a setting screen 760 displayed on the display screen of the terminal device 400. In response to a user's operation using the input device, the processor of the terminal device 400 starts up application software for creating a work plan and displays the setting screen 760 shown in Fig. 8 on the display screen. The user can input outline plan information required for creating a work plan on this setting screen 760.

[0095] 8 shows an example of a setting screen 760 for when tilling with fertilizer application is performed as agricultural work in a rice field. The setting screen 760 is not limited to the one shown in the figure and can be modified as appropriate. The setting screen 760 in the example of FIG. 8 includes a period setting section 761, a time setting section 762, a planting variety selection section 763, a field selection section 764, an operation selection section 765, a machine selection section 766, a fertilizer selection section 767, and an application amount setting section 768.

[0096] The period input by the user is displayed in the period setting section 761. The user inputs the period during which the user wishes to perform the farm work. The days included in the input period are set as candidate days for performing the farm work.

[0097] The time setting section 762 displays the work time input by the user. The user inputs the work time for which the user wishes to perform the farm work. The work time is specified by a start time and an end time. The input work time is set as a candidate time for performing the farm work.

[0098] The crop variety selection section 763 displays a list of varieties of crops to be cultivated (i.e., planted). The user can select a desired variety from the list. In the example of Figure 8, the rice variety "Koshiibuki" is selected.

[0099] The field selection section 764 displays the fields on the map. The user can select any field from the displayed fields. In the example of FIG. 8, the portion showing "Field A" is selected. In this case, the selected "Field A" is set as the field where agricultural work will be performed. The user can also select multiple fields at the same time.

[0100] The work selection section 765 displays a plurality of farming works required to cultivate the selected crop. The user can select one farming work from the plurality of farming works. In the example of FIG. 8, "plowing" is selected from the plurality of farming works. In this case, the selected "plowing" is set as the farming work to be performed.

[0101] The machine selection unit 766 is a section for setting the multicopter to be used in the agricultural work. The machine selection unit 766 may display, for example, the type or model of the multicopter registered in advance by the management device 600, and the type or model of the work implement 200 that can be used. The user can select a specific machine from the displayed machines. In the example of FIG. 8 , the work implement 200 with the model number "XX4511" is selected. In this case, the work implement 200 is set as the machine to be used in the agricultural work.

[0102] The names of multiple fertilizers that have been registered in advance are displayed in the fertilizer selection section 767. The user can select a specific fertilizer from the multiple fertilizers that are displayed. The selected fertilizer is set as the fertilizer to be used in the farm work.

[0103] The spray amount setting section 770 displays a numerical value input from the input device 420. The input numerical value is set as the spray amount.

[0104] When the desired period, work hours, crop variety, field, work, fertilizer, and application amount are entered on the setting screen 760 and "Register" is selected, the communication device of the terminal device 400 transmits the entered information to the management device 600. The processor of the management device 600 stores the received information in a storage device.

[0105] The agricultural work information managed by the management device 600 is not limited to the above. For example, the type and application amount of pesticides used in the field may be set on the setting screen 760. Information about agricultural work other than the agricultural work shown in FIG. 8 may also be set.

[0106] The management device 600 creates a work plan for each multicopter 100 to perform agricultural work based on information received from each user's terminal device 400. For example, the management device 600 determines the actual work date and work time for each multicopter 100 to perform the agricultural work. For example, the management device 600 determines the date and time for performing the agricultural work in each field by comprehensively considering the number, distribution, and usage status of the multicopters 100, the distribution of fields in the area where agricultural work is performed, the desired work date and time of each user, and the estimated work period in the area. The determination of the date and time for performing the agricultural work in each field may be performed using an algorithm utilizing artificial intelligence (AI), such as a deep neural network. The management device 600 notifies the terminal device 400 used by the user of the determined date and time for performing the agricultural work. If the determined date and time for performing the agricultural work differs from the desired date and time of the user, information to that effect may be notified. The management device 600 executes a route plan for each multicopter 100 for each work day based on the determined dates and times when agricultural work will be performed in each field.

[0107] When a work plan is created by the management system as described above, the control device 30 in this embodiment acquires the work content of the multicopter 100 and can change the thrust ratio based on the flight and work content defined in the work plan. That is, during work that requires precise attitude control, such as when performing agricultural work in a field, the thrust ratio can be made smaller than a predetermined reference value, and when moving toward the next work field, the thrust ratio can be made equal to or greater than the reference value.

[0108] Next, an example of an algorithm for changing the ratio of the second thrust of the main rotor 22 to the first thrust of the sub-rotor 12 will be described with reference to FIG. 9 .

[0109] First, in step S10, the control device 30 acquires an initial value of the second thrust of the main rotor 22 (output of the main thrust generating device) and an initial value of the second thrust of the sub-rotor 12 (output of the attitude control device).

[0110] In step S12, the control device 30 acquires the current or upcoming flight conditions. The flight conditions may be specified by a control signal sent from an operator or a ground station. Alternatively, the flight conditions may be defined by a pre-set operation plan. The control device 30 can determine the flight conditions by referring to the operation plan based on the current position and current time of the multicopter 100 obtained from the sensors.

[0111] Flight conditions may be divided into multiple flight modes. The multiple flight modes may include, for example, a first flight mode in which the ratio (thrust ratio) of the second thrust of the main rotor 22 to the first thrust of the sub-rotor 12 is variable, and a second flight mode in which this thrust ratio is fixed. The flight modes may include, for example, hovering, horizontal flight (forward, backward, or sideways movement (aileron)), ascent, descent, and rotation (rudder). The control device 30 may set the thrust ratio to a value greater than 1, for example, during ascent and hovering. This allows the main rotor 22 to efficiently generate large thrust. The control device 30 may set the thrust ratio to a value smaller than the value during hovering (for example, a value smaller than 1) when adjusting the attitude (yaw, pitch, and / or roll) of the aircraft to a desired attitude, for example, for landing, horizontal flight, or rudder operations. This makes it possible to prevent the large thrust and rotational moment generated by the rotation of the main rotor 22 from interfering with the attitude control function of the sub-rotor 12.

[0112] The control device 30 may be configured to change the thrust ratio in response to a user's operation using an external device such as a remote monitoring device or a pilot machine, thereby enabling the user to adjust the balance between thrust generation efficiency and attitude control responsiveness, for example, to make piloting easier.

[0113] In step S14, the control device 30 acquires meteorological information including information indicating wind speed. The control device 30 may acquire wind speed measurements from a sensor group, or may acquire meteorological information from a ground station via communication.

[0114] In step S16, the control device 30 determines whether to change the ratio of the second thrust of the main rotor 22 to the first thrust of the sub-rotor 12 based on flight conditions, weather information, etc. If the answer is "No," the process returns to step S10. On the other hand, if the answer is "Yes," the control device 30 proceeds to step S18, where it reduces or increases the second thrust of the main rotor 22, i.e., the output of the main thrust device. The control device 30 also increases or decreases the first thrust of the sub-rotor 12, i.e., the output of the attitude control device.

[0115] According to the algorithm of FIG. 9, the control device 30 can appropriately change the thrust ratio depending on the current or future flight conditions (including the type of work being performed) and weather conditions.

[0116] The above flow is merely an example. Hereinafter, with reference to Fig. 10, another example of an algorithm for changing the ratio of the second thrust of the main rotor 22 to the first thrust of the sub-rotor 12 will be described. In this example, when the amount of change in the attitude angle is equal to or greater than a predetermined value, the output of the main thrust generator is reduced and the output of the attitude control device is increased in order to achieve a large change in the attitude angle.

[0117] First, in step S20, the control device 30 acquires an initial value of the second thrust of the main rotor 22 (output of the main thrust generating device) and an initial value of the second thrust of the sub-rotor 12 (output of the attitude control device).

[0118] In step S22, the control device 30 estimates the current attitude angle of the multicopter 100. The control device 30 may acquire an estimated value or a measured value of the attitude angle from a sensor that estimates or measures the attitude angle.

[0119] In step S24, the control device 30 acquires a target attitude angle. The control device 30 may determine the target attitude angle based on flight conditions (task details) and weather information.

[0120] In step S26, the control device 30 calculates the amount of change in the attitude angle and determines whether the amount of change is equal to or greater than a predetermined value. The amount of change in the attitude angle is determined by the difference between the current estimated attitude angle and the target attitude angle. The larger this "amount of change," the larger the amount of change in attitude. If the result of the determination is "No," the process returns to step S20. If the result is "Yes," the process proceeds to step S28.

[0121] In step S28, the control device 30 determines whether the mode is one in which the thrust ratio is variable. When the attitude angle changes to various values ​​within a short period of time, it may be preferable to fix the thrust ratio. In particular, because the response speed of an internal combustion engine is slower than that of a motor, it is not preferable to frequently change the magnitude of the output (second thrust) of the main rotor 22. For this reason, for example, after the output (second thrust) of the main rotor 22 is reduced, the ratio between the first thrust of the sub-rotor 12 and the second thrust of the main rotor 22 may be fixed regardless of the amount of change in the attitude angle until a predetermined time (e.g., one second or more, or five seconds or more) has elapsed. If the result of the determination in step S28 is "No," the process returns to step S20. If the result is "Yes," the process proceeds to step S30.

[0122] In step S30, the control device 30 reduces the output of the main thrust generator and increases the output of the attitude control device. In other words, the control device 30 reduces the second thrust of the main rotor 22 and increases the first thrust of the sub-rotor 12.

[0123] According to the algorithm of Figure 10, the control device 30 can reduce the second thrust and increase the first thrust when changing the attitude of the unmanned aerial vehicle 100.

[0124] Thus, according to this embodiment, when precise attitude control is required, it is possible to reduce the thrust of a rotor with a relatively slow response speed and increase the thrust of a rotor with a relatively fast response speed.

[0125] 11 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.

[0126] 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).

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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. The companion computer may execute the processes shown in Figures 9 and 10, and issue flight-related commands based on the results of those processes to the flight controller.

[0132] 12 , 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 30 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.

[0133] In the unmanned aerial vehicle according to the above embodiments, the "attitude control device" includes multiple electric motors, and the "main thrust generating device" includes an internal combustion engine. In other words, the unmanned aerial vehicle according to the above embodiments includes the rotary drive device 3D shown in FIG. 1A. However, even in the rotary drive devices 3A, 3B, and 3C shown in FIG. 1A, by differentiating some of the motors 14 or power transmission mechanisms 23 from the other motors 14 or power transmission mechanisms 23, it is possible to realize an unmanned aerial vehicle that includes an "attitude control device" and a "main thrust generating device."

[0134] The unmanned aerial vehicle may also be equipped with multiple internal combustion engines with different power outputs and response speeds. In this case, an internal combustion engine with a relatively low power output and a relatively high response speed may constitute an "attitude control device," and an internal combustion engine with a relatively high power output and a relatively low response speed may constitute a "main thrust generating device."

[0135] This specification discloses an unmanned aerial vehicle described in the following items.

[0136] [Item 1] An unmanned aerial vehicle having multiple rotors, comprising: a plurality of attitude control devices that respectively drive a plurality of first rotors included in the plurality of rotors; a main thrust generating device that drives at least one second rotor included in the plurality of rotors; and a control device that controls the flight of the unmanned aerial vehicle, the control device changing the ratio of the second thrust output from the main thrust generating device to the first thrust output from the plurality of attitude control devices.

[0137] [Item 2] The unmanned aerial vehicle described in Item 1, wherein the control device reduces the second thrust and increases the first thrust when changing the attitude of the unmanned aerial vehicle.

[0138] [Item 3] The unmanned aerial vehicle according to item 1 or 2, wherein the control device changes the ratio depending on current weather conditions or work content.

[0139] [Item 4] The unmanned aerial vehicle according to item 1 or 2, wherein the control device predicts weather conditions or work content and changes the ratio according to the predicted weather conditions or work content.

[0140] [Item 5] The unmanned aerial vehicle described in any one of Items 1 to 4, wherein the control device reduces the second thrust and increases the first thrust when working in a work area compared to when moving between work areas.

[0141] [Item 6] The unmanned aerial vehicle according to Item 5, wherein the work is agricultural work.

[0142] [Item 7] The control device is configured to control the flight of the unmanned aerial vehicle in a plurality of flight modes, and the plurality of flight modes include a first flight mode that varies the ratio and a second flight mode that fixes the ratio. An unmanned aerial vehicle described in any one of items 1 to 6.

[0143] [Item 8] An unmanned aerial vehicle described in any one of Items 1 to 7, wherein the diameter of the second rotor is larger than the diameter of each of the plurality of first rotors.

[0144] [Item 9] An unmanned aerial vehicle described in any one of items 1 to 8, wherein each of the plurality of attitude control devices includes an electric motor, and the main thrust generating device includes an internal combustion engine.

[0145] [Item 10] The unmanned aerial vehicle according to Item 9, wherein the internal combustion engine generates electric power for rotating the electric motor, and the unmanned aerial vehicle is equipped with a battery that stores at least a portion of the electric power.

[0146] [Item 11] A control method for a parallel hybrid unmanned aerial vehicle having multiple rotors, the unmanned aerial vehicle having: a plurality of electric motors that respectively drive a plurality of first rotors included in the plurality of rotors; and an internal combustion engine that drives at least one second rotor included in the plurality of rotors; and the control method for the unmanned aerial vehicle changing the ratio of the second thrust of the at least one second rotor to the first thrust of the plurality of first rotors.

[0147] [Item 12] A method for controlling an unmanned aerial vehicle according to Item 11, wherein the second thrust is decreased and the first thrust is increased when changing the attitude of the unmanned aerial vehicle.

[0148] 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.

[0149] 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, 12a: Propeller, 12b: Propeller, 14: Motor, 16: ESC, 22: Main rotor, 52: Battery, 54: Battery management device

Claims

1. 1. An unmanned aerial vehicle having multiple rotors, a plurality of attitude control devices that respectively drive a plurality of first rotors included in the plurality of rotors; a main thrust generating unit that drives at least one second rotor included in the plurality of rotors; a control device for controlling flight of the unmanned aerial vehicle, the control device changing a ratio between a first thrust output from the plurality of attitude control devices and a second thrust output from the main thrust generating device; An unmanned aerial vehicle comprising:

2. The unmanned aerial vehicle of claim 1 , wherein the control device decreases the second thrust and increases the first thrust when changing the attitude of the unmanned aerial vehicle.

3. The unmanned aerial vehicle according to claim 1 or 2, wherein the control device changes the ratio depending on current weather conditions or work content.

4. The unmanned aerial vehicle according to claim 1 or 2, wherein the control device predicts weather conditions or work content and changes the ratio according to the predicted weather conditions or work content.

5. The unmanned aerial vehicle described in claim 1 or 2, wherein the control device reduces the second thrust and increases the first thrust when working in a work area compared to when moving between work areas.

6. The unmanned aerial vehicle according to claim 5 , wherein the work is agricultural work.

7. the controller is configured to control flight of the unmanned aerial vehicle in a plurality of flight modes; The unmanned aerial vehicle according to claim 1 or 2, wherein the plurality of flight modes include a first flight mode in which the ratio is variable, and a second flight mode in which the ratio is fixed.

8. The unmanned aerial vehicle according to claim 1 or 2, wherein the diameter of the second rotor is larger than the diameter of each of the plurality of first rotors.

9. each of the plurality of attitude control devices includes an electric motor; The unmanned aerial vehicle of claim 1 or 2, wherein the main thrust generating device includes an internal combustion engine.

10. the internal combustion engine generates electric power to rotate the electric motor; The unmanned aerial vehicle of claim 9 , further comprising a battery that stores at least a portion of the power.

11. 1. A method for controlling a parallel hybrid multi-rotor unmanned aerial vehicle, comprising: The unmanned aerial vehicle comprises: a plurality of electric motors that respectively drive a plurality of first rotors included in the plurality of rotors; an internal combustion engine that drives at least one second rotor included in the plurality of rotors; It is equipped with A method for controlling an unmanned aerial vehicle, comprising changing a ratio between a first thrust of the plurality of first rotors and a second thrust of the at least one second rotor.

12. The method for controlling an unmanned aerial vehicle according to claim 11 , further comprising: decreasing the second thrust and increasing the first thrust when changing the attitude of the unmanned aerial vehicle.