Unmanned aerial vehicle, and control system and control method of unmanned aerial vehicle

Abstract

This unmanned aerial vehicle includes a plurality of rotors, a plurality of electric motors for driving the plurality of rotors respectively, a power source, and a controller that controls the supply of first power from the power source to the plurality of electric motors and the supply of second power from the power source to external work equipment, and controls the operation of the plurality of electric motors. Upon detection of an abnormality of a device included in the unmanned aerial vehicle, the controller stops the supply of the second power to the work equipment, maintains the supply of the first power to the plurality of electric motors, and executes a flight by the plurality of rotors.

Description

Unmanned aerial vehicle, and control system and control method for unmanned aerial vehicle

[0001] The present disclosure relates to unmanned aerial vehicles, and control systems and methods for 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 aerial vehicle) that changes its flight position in conjunction with the operation of agricultural machinery.

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

[0005] The present disclosure provides a system capable of performing various ground operations by supplying power from the unmanned aerial vehicle to a work machine coupled to the unmanned aerial vehicle. The present disclosure also provides a system and method for appropriately controlling the operation of the unmanned aerial vehicle when an abnormality occurs in a device of the unmanned aerial vehicle while the unmanned aerial vehicle is flying and driving the work machine.

[0006] In an exemplary but non-limiting embodiment, the unmanned aerial vehicle of the present disclosure includes a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a control device. The control device controls the supply of a first electric power from the power source to the plurality of electric motors and the supply of a second electric power from the power source to an external work machine, and controls the operation of the plurality of electric motors. When the control device detects an abnormality in a device included in the unmanned aerial vehicle, the control device stops the supply of the second electric power to the work machine and maintains the supply of the first electric power to the plurality of electric motors to perform flight using the plurality of rotors.

[0007] In an exemplary but non-limiting embodiment, a control system for an unmanned aerial vehicle according to the present disclosure is a control system for an unmanned aerial vehicle including a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a coupling device that couples a work machine that performs ground work. The control system includes a control device that controls the supply of a first electric power from the power source to the plurality of electric motors and the supply of a second electric power from the power source to the work machine, and that controls the operation of the plurality of electric motors. When the control device detects an abnormality in equipment included in the unmanned aerial vehicle, the control device stops the supply of the second electric power to the work machine and maintains the supply of the first electric power to the plurality of electric motors, thereby allowing the unmanned aerial vehicle to fly using the plurality of rotors.

[0008] In an exemplary but non-limiting embodiment, a control method for an unmanned aerial vehicle according to the present disclosure is a control method for an unmanned aerial vehicle including a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a coupling device that couples a work implement that performs ground work. The control method includes controlling a supply of a first electric power from the power source to the plurality of electric motors and a supply of a second electric power from the power source to the work implement, controlling operation of the plurality of electric motors, detecting an abnormality in equipment included in the unmanned aerial vehicle, and, when the abnormality is detected, stopping the supply of the second electric power to the work implement and maintaining the supply of the first electric power to the plurality of electric motors to perform flight using the plurality of rotors.

[0009] According to the embodiments of the unmanned aircraft, and its control system and control method disclosed herein, in an unmanned aircraft that flies while supplying power to a work machine, if an abnormality occurs in the equipment, it becomes possible to appropriately control the operation of the unmanned aircraft.

[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 a basic configuration example of a battery-powered multicopter. FIG. 6 is a block diagram showing a basic configuration example of a series hybrid multicopter. FIG. 7 is a block diagram showing a basic configuration example of a parallel hybrid multicopter. FIG. 8 is a top view schematically showing a multicopter according to an embodiment of the present disclosure. FIG. 9 is a side view schematically showing a multicopter. FIG. 10 is a block diagram showing an example of a system configuration of a multicopter. FIG. 11 is a flowchart showing the operation of the multicopter. FIG. 12 is a plan view showing an example of a flight path of the multicopter. FIG. 13 is a plan view showing another example of a flight path of the multicopter. FIG. 14 is a first diagram showing an example of an operation when an abnormality occurs in the drive system of the main rotor during work. FIG. 15 is a second diagram showing an example of an operation when an abnormality occurs in the drive system of the main rotor during work. Fig. 3 is a third diagram showing an example of operation when an abnormality occurs in the drive system of the main rotor during work. Fig. 4 is a block diagram showing an example of a system configuration in a battery-powered multicopter. Fig. 5 is a block diagram showing an example of the hardware configuration of a control device. Fig. 6 is a diagram schematically showing an example of a communication network to which a multicopter is connected.

[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 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.

[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." 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.

[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. 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.

[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 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.

[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.

[0035] 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.

[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 multicopter 100 shown in FIG. 3B is equipped with a coupling device for suspending the work implement 200. The "coupling" between the multicopter 100 and the work implement 200, etc., 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, which is a coupling device used for coupling the airframe main body 120 to the work machine 200. 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 of 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, the sensor group 4b, and the communication device 4c of the airframe 4 of the multicopter 10 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 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.

[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 is capable of changing the ratio (thrust ratio) between the total thrust (first thrust) of the sub-rotor 12 obtained from the multiple motors 14 and the total thrust (second thrust) of the main rotor 22 obtained from the main rotor drive unit 24.

[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, 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.

[0065] <Example of Operation When Abnormality is Detected> In the example shown in FIG. 4 , the power generation device 42 and the battery 52 function as power sources for the multicopter 100. These power sources supply power (first power) to the multiple motors 14 and power (second power) to the external work machine 200. Furthermore, the power generation device 42 supplies power (third power) for charging the battery 52. ​​The control device 30 controls the supply of the first power from the power source to the multiple electric motors 14 and the supply of the second power from the power source to the work machine 200 via the power supply device 76. In the example shown in FIG. 4 , the control device 30 can control the supply of power from the power generation device 42 or the battery 52 to the work machine 200 by controlling the power switch 56. Furthermore, the control device 30 can control the supply of power from the battery 52 to the multiple motors 14 by controlling the power switch 56. Furthermore, the control device 30 can control the supply of power from the power generation device 42 to the multiple motors 14 by controlling the power management device 44.

[0066] In this embodiment, the sensor group 72 includes at least one sensor that measures the accelerator position, intake air temperature, engine speed, and / or temperatures of various parts of the main rotor drive unit 24, which is an internal combustion engine, and outputs sensor data indicating the measured values. The sensor data can be used not only to control the internal combustion engine but also to detect abnormalities in the internal combustion engine. The sensor group 72 is not limited to the internal combustion engine, and may include sensors for detecting abnormalities in other devices, such as the power generation unit 42, the main rotor 22, a power transmission system to the main rotor 22, and / or a fuel supply system to the internal combustion engine. More specifically, the sensor group 72 may include sensors that detect, for example, the output voltage or output current of the power generation unit 42, the rotational speed of the rotor of the power generation unit 42, the rotational speed of the main rotor 22, the rotational speed of a gear included in the power transmission system of the main rotor 22, the amount of fuel remaining in the fuel tank, the temperature of the fuel tank, the temperature of the coolant for the internal combustion engine, or the rotational speed or torque of the output shaft of the internal combustion engine. The control device 260 may be configured to monitor the status of at least one of the internal combustion engine, the power generation device, the main rotor 22, the power transmission system to the main rotor 22, and the fuel supply system to the internal combustion engine based on the output from one or more such sensors.

[0067] The control device 30 can detect an abnormality in the equipment included in the multicopter 100 based on sensor data output from at least one sensor included in the sensor group 72. For example, the control device 260 can detect an abnormality in the state of at least one of the internal combustion engine, the power generation device, the main rotor 22, the power transmission system to the main rotor 22, and the fuel supply system to the internal combustion engine. When the control device 30 detects an abnormality in the equipment, it stops the supply of power to the work machine 200 and maintains the supply of power to the multiple electric motors 14 to perform flight using the multiple sub-rotors 12. For example, if the control device 30 detects an abnormality in the equipment while flying the multicopter 100 while supplying power to the work machine 200 via the power supply device 76, it operates in an emergency flight mode in which it stops the supply of power to the work machine 200 and causes the multicopter 100 to fly. More specifically, if the control device 30 detects an equipment abnormality while controlling the multiple motors 14 and the main rotor drive unit 24 (internal combustion engine) to perform flight while supplying power to the work machine 200, it controls the power switch 56 to stop the supply of power from the power generation device 42 and the battery 52 to the work machine 200. At this time, the control device 30 maintains the supply of power from the battery 52 to the multiple electric motors 14 to continue flight using the multiple sub-rotors 12. If the equipment abnormality is an abnormality in the drive system of the main rotor 22, the control device 30 stops operation of the main rotor 22 via the main rotor control unit 26 and continues flight by driving only the sub-rotors 12. Here, the drive system of the main rotor 22 includes the main rotor 22, a power transmission system to the main rotor 22, the internal combustion engine, the power generation device 42, and a fuel supply system to the internal combustion engine. When the multicopter 100 is flying by driving only the sub-rotors 12, the rotational speed of each sub-rotor 12 may be increased to compensate for the reduction in thrust that occurs when the main rotor 22 is stopped. After stopping the power supply to the work machine 200 and the operation of the main rotor 22, the control device 30 may drive only the sub-rotors to fly the multicopter 100 up to the sky above a possible landing point, and then reduce the rotational speed of each sub-rotor 12 to land the multicopter 100 at that point.

[0068] This operation makes it possible to reduce the loss of energy from the battery 52 due to power supply to the work machine 200 and ensure sufficient flight time in emergency flight mode if an equipment abnormality (e.g., failure) occurs during flight involving ground work by the work machine 200. As a result, even if the main rotor 22 cannot be driven due to a malfunction in the drive system of the main rotor 22, for example, it is possible to continue flight by driving only the sub-rotor 12 and fly the multicopter 100 to a point where it can land.

[0069] Note that when the control device 30 detects an abnormality in the equipment, instead of stopping the supply of power to the work machine 200, the control device 30 may reduce the amount of power supplied to the work machine 200. The control device 30 may adjust the amount of power supplied to the work machine 200 based on the amount of power required until landing and the remaining amount of energy stored in the battery 52 (power source). For example, the control device 30 may limit the amount of power supplied to the work machine 200 so that the smaller the value obtained by subtracting the amount of power estimated to be required until landing from the remaining energy amount in the battery 52 when the abnormality is detected, the smaller the amount of power supplied to the work machine 200. By such control, the work machine 200 can be driven to the extent possible even when an abnormality occurs.

[0070] As described above, in this embodiment, even if the power supply from the power generation device 42 to the multiple motors 14 is stopped due to an abnormality in equipment such as the internal combustion engine or the power generation device 42, it is possible to stop or limit the power supply to the work machine 200 and maintain the power supply from the battery 52 to the multiple motors 14. This allows only the multiple sub-rotors 12 to be driven, and the flight of the multicopter 100 to continue for a while. By incorporating a function based on this fail-safe concept, it is possible to continue the flight of the multicopter 100 and land the multicopter 100 at a possible landing point even if an abnormality occurs in the equipment.

[0071] To achieve this function, the battery management device 54 in this embodiment controls charging so as to maintain the state of charge (SOC) of the battery 52 at a constant level or higher when no equipment abnormalities are occurring. For example, while the work machine 200 is being driven and flying with the multiple sub-rotors 12 and the main rotor 22, the battery management device 54 may maintain the state of charge of the battery 52 at a value higher than a threshold (e.g., 80%) required for continuing flight with the multiple sub-rotors 12 and then landing if an equipment abnormality is detected. The threshold may be set, for example, within a range of 70% to 90%. This threshold may be set to an appropriate value depending on the total weight of the multicopter 100 and the work machine 200. For example, the control device 30 may acquire information about the weight of the work machine 200 suspended by the coupling device of the multicopter 100 and change the threshold value depending on the weight. If the weight of the work machine 200 is known and the weight information is pre-recorded in a storage device, the control device 30 can acquire the weight information of the work machine 200 from the storage device. Alternatively, the sensor group 72 may include a sensor that measures the weight of the work implement 200 suspended from the multicopter 100. In this case, the control device 30 can acquire information about the weight of the work implement 200 from values ​​measured by the sensor. The control device 30 may also estimate the weight of the work implement 200 based on, for example, the rotational speeds of the multiple sub-rotors 12 and the main rotor 22 during hovering, and the known weight of the multicopter 100. Various types of work implements 200 may be coupled to the coupling device of the multicopter 100. Furthermore, when the work implement 200 performs work such as spraying or harvesting, the weight of the work implement 200 (i.e., payload) may vary as the work progresses. By measuring the weight of the work implement 200 with a sensor or estimating it based on the rotational speed of each rotor, information about the variable weight of the work implement 200 can be appropriately acquired.

[0072] Next, an example of the operation of transitioning to emergency flight mode when an abnormality occurs in equipment such as the drive system of the main rotor 22 during flight will be described with reference to Figure 5. Figure 5 is a flowchart showing an example of the operation performed by the control device 30. In this example, the multicopter 100 drives the work implement 200 to perform predetermined agricultural work while automatically flying along a preset flight path.

[0073] First, in step S100, the control device 30 drives each sub-rotor 12 (first rotor) and each main rotor 22 (second rotor) to initiate flight of the multicopter 100. The control device 30 controls the multiple ESCs 16 to rotate the multiple motors 14, thereby driving each sub-rotor 12. The control device 30 also drives each main rotor 22 by having the main rotor control unit 26 drive the main rotor drive unit 24 (internal combustion engine). The rotational speed of each main rotor 22 and each sub-rotor 12 can be determined based on a preset thrust ratio between the main rotor 22 and the sub-rotor 12. Flight can be initiated, for example, by a user operating a pilot or according to a preset program.

[0074] In step S101, the control device 30 determines whether the multicopter 100 has reached the sky above the work start point. The work start point is, for example, a point where agricultural work begins in a farm field. The control device 30 can determine whether the multicopter 100 has reached the sky above the work start point based on the position of the multicopter 100 measured by the GNSS receiver included in the sensor group 72 and map data of the area including the farm field. When the multicopter 100 has reached the sky above the work start point, the process proceeds to step S102.

[0075] In step S102, the control device 30 starts supplying power to the work machine 200, and starts a flight involving work by the work machine 200 (hereinafter, sometimes referred to as a "work flight"). The supply of power to the work machine 200 can be executed by controlling the power switch 56 to electrically connect the power generation device 42 and the power supply device 76.

[0076] In step S103, the control device 30 acquires sensor data indicating the status of the equipment from the sensor group 72. The sensor data may include data indicating the status of the drive system of the main rotor 22. The sensor data may include, for example, data indicating the output voltage or output current of the power generation device 42, the rotational speed of the rotor of the power generation device 42, the rotational speed of the main rotor 22, the rotational speed of a gear included in the power transmission system of the main rotor 22, the amount of fuel remaining in the fuel tank, the temperature of the fuel tank, the temperature of the coolant for the internal combustion engine, and / or the rotational speed or torque of the output shaft of the internal combustion engine.

[0077] In step S104, the control device 30 determines, based on the sensor data, whether or not an abnormality has been detected in the drive system of the main rotor 22. If an abnormality has been detected (Yes), the process proceeds to step S107. If no abnormality has been detected (No), the process proceeds to step S105.

[0078] In step S105, the control device 30 determines whether the work performed by the work machine 200 has been completed. The control device 30 can determine that the work has been completed when, for example, the position of the multicopter 100 measured by the GNSS receiver is above a preset work end point. If the work has been completed (Yes), the process proceeds to step S106. If the work has not been completed (No), the process returns to step S103.

[0079] In step S106, the control device 30 stops power supply to the work machine 200 and drives each sub-rotor 12 and each main rotor 22 to fly the multicopter 100 to the sky above a predetermined possible landing point. The possible landing point is a predetermined point such as a point in a field where no agricultural work is being performed (e.g., a headland), a storage location for the multicopter 100, or a supply point where agricultural materials such as chemicals or fertilizer are replenished to the multicopter 100. When the multicopter 100 reaches the sky above the possible landing point, the process proceeds to step S109.

[0080] If an abnormality is detected in the drive system of the main rotor 22 in step S104, the process proceeds to step S107. In step S107, the control device 30 stops the power supply to the work machine 200 and the drive of the main rotor 22. Note that instead of completely stopping the power supply to the work machine 200, the amount of power supplied to the work machine 200 may be reduced. At this time, the control device 30 controls the power switch 56 to stop the supply of power from the power generation device 42 and the battery 52 to the power supply device 76, and starts the supply of power from the battery 52 to the multiple motors 14. Note that instead of controlling the power switch 56, the control device 30 may control the power supply to the work machine 200 by controlling a switch included in the power supply device 76.

[0081] In step S108, the control device 30 drives only the sub-rotor 12 to fly the multicopter 100 to above a possible landing point. This possible landing point may be a different point from the possible landing point in step S106. In step S108, the sub-rotor 12 is driven by the power stored in the battery 52, so flight may not be able to continue for very long. For this reason, in step S108, the control device 30 may be configured to fly the multicopter 100 to above a possible landing point that is relatively close to the position where power supply to the work machine 200 and drive of the main rotor 22 are stopped. When the multicopter 100 reaches above the possible landing point, the process proceeds to step S109.

[0082] In step S109, the control device 30 lands the multicopter 100 at a possible landing point by reducing the rotational speed of each rotor.

[0083] FIG. 6A is a plan view showing an example of the flight path of the multicopter 100 in this embodiment. In this example, the multicopter 100 flies while performing agricultural work, such as spraying fertilizer or pesticides or mowing, in a field 70 using a work implement 200. For this reason, the flight path of the multicopter 100 meanders regularly, as indicated by the arrows in the figure. The control device 30 controls the position, altitude, and attitude of the multicopter 100 with high precision, thereby enabling it to perform necessary ground work on areas of the field 70 where crops exist or on the ground itself. To perform such work, the flight altitude along the flight path can be controlled to a preferred level, for example, between 0.1 m and 5 m.

[0084] In the example of Fig. 6A, no abnormalities occur in any of the devices included in the multicopter 100 while agricultural work is being performed in the field 70. Therefore, after the agricultural work is completed, the control device 30 stops the work implement 200 and lands the multicopter 100 at a possible landing point on the periphery of the field 70 (e.g., a headland). Note that, as shown in Fig. 6B, after the agricultural work is completed, the multicopter 100 may stop the work implement 200 and fly to and land in an area 73 located outside the field 70. Area 73 is, for example, a predetermined location such as a storage location for the multicopter 100 or a supply location for agricultural materials.

[0085] FIG. 7A illustrates an example of the operation of the multicopter 100 when an abnormality occurs in a component included in the multicopter 100, such as the drive system of the main rotor 22. In this example, while the multicopter 100 is driving the work implement 200 to perform a work flight in the field 70, the control device 30 detects an abnormality in the drive system of the main rotor 22 (e.g., the internal combustion engine or the power generation device 42). In this case, the control device 30 stops driving the main rotor 22 and the work implement 200 and, as shown in FIG. 7B , continues flight by driving only the sub-rotor 12, and lands at a possible landing point. As described above, instead of stopping the power supply to the work implement 200, the amount of power supplied to the work implement 200 may be reduced to continue ground work to the extent possible. In the example of FIG. 7B , the control device 30 lands the multicopter 100 at a possible landing point on a headland where no work is being performed in the field 70. Without being limited to this example, for example, as shown in FIG. 7C , the control device 30 may fly the multicopter 100 to a possible landing area 75 outside the field 70 by driving only the sub-rotor 12 and land it there. The area 75 may be the same area as the area 73 shown in FIG. 6B . However, if the weight (i.e., payload) of the work machine 200 is large or the storage capacity of the battery 52 is small, the distance that can be flown by driving only the sub-rotor 12 is short, and it may be difficult to fly to the area 73 shown in FIG. 6B . In this case, the control device 30 lands the multicopter 100 at a possible landing point near the area in the field 70 where work will be performed. Note that position information of the possible landing point is stored in advance in a storage device, and the control device 30 can move the multicopter 10 to the possible landing point based on the position information and the positioning results of the GNSS receiver.

[0086] As described above, when the control device 30 in this embodiment detects an abnormality in equipment included in the multicopter 100 during work flight, it can continue flight by stopping or reducing the supply of power to the work unit 200 and maintaining the supply of power to the multiple electric motors 14 to drive the multiple sub-rotors 12. In particular, when the control device 30 detects an abnormality in the internal combustion engine (main rotor drive unit 24), the power generation device 42, the main rotor 22, the power transmission system to the main rotor 22, or the fuel supply system to the internal combustion engine, it can stop or limit the supply of power to the work unit 200 and the drive of the main rotor 22, and continue flight by driving only the sub-rotor 12. With this control, flight can continue for a while using the sub-rotor 12 even after an abnormality is detected, allowing the multicopter 100 to land appropriately at a possible landing site.

[0087] Although the multicopter 100 in this embodiment flies automatically along a preset flight path, the multicopter 100 may also fly according to the operation of a user using a piloted device. Even in this case, if the control device 30 detects an abnormality in the equipment during a work flight, it may stop or reduce the power supply to the work machine 200 and continue flight by driving the sub-rotor 12.

[0088] Although the multicopter 100 in this embodiment has a parallel hybrid drive configuration, it may also have other configurations, such as a battery drive configuration (see FIG. 2A) or a series hybrid drive configuration (see FIG. 2B). Below, an example in which the control method of the present disclosure is applied to a battery drive multicopter will be described.

[0089] Fig. 8 is a block diagram showing an example of the system configuration of a battery-powered multicopter 100B. The configuration shown in Fig. 8 corresponds to the configuration shown in Fig. 4 excluding the main rotor 22, main rotor drive unit 24, main rotor control unit 26, power generation device 42, and power management device 44. The multicopter 100B shown in Fig. 8 does not include a main rotor 22, and flies by rotating multiple rotors 12 powered by a battery 52.

[0090] In the example of FIG. 8 , the sensor group 72 may include at least one sensor that senses the operating state of each rotor 12, each motor 14, or each ESC 16. The control device 30 can detect an abnormality in any of the rotors 12, motors 14, or ESCs 16 based on the sensor data output from the sensor. If the control device 30 detects an abnormality in any of the devices during a work flight, it may be configured to stop or reduce the power supply to the work vehicle 200, stop the rotation of the rotor 12 corresponding to the abnormal device, and continue flight by rotating only the remaining rotors 12. At this time, to prevent thrust imbalance caused by stopping a rotor 12, the rotation of the other rotors 12 diagonally opposite the rotor 12 corresponding to the abnormal device may also be stopped. Stopping or reducing the power supply to the work vehicle 200 prevents the decrease in the amount of charge stored in the battery 52 and makes it easier to drive the remaining sub-rotors 12 to fly to a landing point.

[0091] In the above examples, the operation when an abnormality in the drive system of the main rotor 22 or the sub-rotor 12 is detected has been described. However, similar control can be applied when an abnormality in other equipment is detected. For example, if an abnormality occurs in the communication device 74, the sensor group 72, or other electrical equipment, it may be necessary to stop the work flight and land at an appropriate location for maintenance. Therefore, when the control device 30 detects an abnormality in the communication device 74, the sensor group 72, or other electrical equipment based on sensor data, it may control the flight of the multicopter 100 to stop or limit the power supply to the work machine 200, drive the sub-rotor 12 (and the main rotor 22, if possible) to perform minimal flight, and land at an appropriate location.

[0092] The control device 30 in the embodiment of the present disclosure can be realized by a digital computer system programmed to execute the processes described with reference to FIGS.

[0093] 9 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.

[0094] 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).

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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 Figure 5 and issue flight-related commands based on the results of those processes to the flight controller.

[0100] 10 , 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) 600 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.

[0101] This specification discloses an unmanned aerial vehicle, a control system, and a control method described in the following items.

[0102] [Item 1] An unmanned aerial vehicle comprising: a plurality of rotors; a plurality of electric motors that respectively drive the plurality of rotors; a power source; a coupling device that couples a work machine that performs ground work; and a control device that controls the supply of a first power from the power source to the plurality of electric motors and the supply of a second power from the power source to the work machine, and controls the operation of the plurality of electric motors, wherein when the control device detects an abnormality in equipment included in the unmanned aerial vehicle, it stops the supply of the second power to the work machine and maintains the supply of the first power to the plurality of electric motors, thereby performing flight using the plurality of rotors.

[0103] [Item 2] The unmanned aerial vehicle described in Item 1, wherein when the control device detects the abnormality while controlling the multiple electric motors to fly while supplying the second power to the work machine, the control device stops the supply of the second power to the work machine, maintains the supply of the first power to the multiple electric motors to continue flight using the multiple rotors, and then reduces the rotational speed of the multiple rotors to land the unmanned aerial vehicle.

[0104] [Item 3] The unmanned aerial vehicle described in Item 1 or 2, wherein the multiple rotors are multiple first rotors, and further comprising: at least one second rotor; an internal combustion engine that drives the at least one second rotor; a power generation device that is driven by the internal combustion engine to generate third electric power; and a battery that stores the third electric power, wherein the power source includes the power generation device and the battery, and the control device monitors the status of at least one of the internal combustion engine, the power generation device, the second rotor, a power transmission system to the second rotor, and a fuel supply system to the internal combustion engine, and when an abnormality in at least one of the statuses is detected, stops the supply of the second electric power to the work machine, maintains the supply of the first electric power to the multiple electric motors, stops the at least one second rotor, and performs flight using the multiple first rotors.

[0105] [Item 4] An unmanned aerial vehicle as described in Item 3, further comprising a battery management device that controls charging and discharging of the battery, wherein the battery management device maintains the battery charge rate at a value higher than a threshold required for continuing flight by the multiple first rotors and then landing if the abnormality is detected while flight by the multiple first rotors and the at least one second rotor is being performed while the work machine is powered by the second power.

[0106] [Item 5] The unmanned aerial vehicle according to Item 4, wherein the control device acquires information indicating a weight of the work machine and changes the threshold value of the charging rate in accordance with the weight.

[0107] [Item 6] An unmanned aerial vehicle described in any one of items 1 to 5, further comprising at least one sensor that outputs sensor data for detecting an abnormality in the equipment, and the control device detects an abnormality in the equipment based on the sensor data.

[0108] [Item 7] A control system for an unmanned aerial vehicle comprising a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a coupling device that couples a work machine that performs ground work, the control system further comprising a control device that controls the supply of a first power from the power source to the plurality of electric motors and the supply of a second power from the power source to the work machine, and controls the operation of the plurality of electric motors, wherein when the control device detects an abnormality in equipment included in the unmanned aerial vehicle, the control system stops the supply of the second power to the work machine and maintains the supply of the first power to the plurality of electric motors, thereby performing flight using the plurality of rotors.

[0109] [Item 8] A control method for an unmanned aerial vehicle having a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a coupling device that couples a work machine that performs ground work, the control method including: controlling the supply of a first power from the power source to the plurality of electric motors and the supply of a second power from the power source to the work machine; controlling the operation of the plurality of electric motors; detecting an abnormality in equipment included in the unmanned aerial vehicle; and, when the abnormality is detected, stopping the supply of the second power to the work machine and maintaining the supply of the first power to the plurality of electric motors to perform flight using the plurality of rotors.

[0110] 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.

[0111] 2...Rotor (propeller), 3...Rotational drive device, 4...Airframe body, 4a...Control device, 4b...Sensor group, 4c...Communication device, 5...Airframe frame, 10...Multicopter, 12...Sub-rotor, 14...Motor, 16...ESC, 22...Main rotor, 24...Main rotor drive section, 26...Main rotor control unit, 30...Control device, 42...Power generation device, 44...Power management device, 52...Battery, 54...Battery management device, 72...Sensor group, 74...Communication device, 76...Power supply device, 100...Multicopter, 200...Work machine

Claims

1. A plurality of rotors; a plurality of electric motors that respectively drive the plurality of rotors; a power source; a coupling device for coupling a work machine that performs ground work; a control device that controls the supply of a first electric power from the electric power source to the plurality of electric motors and the supply of a second electric power from the electric power source to the work machine, and that controls the operation of the plurality of electric motors; An unmanned aerial vehicle comprising: When the control device detects an abnormality in a device included in the unmanned aerial vehicle, the control device stops the supply of the second electric power to the work machine and maintains the supply of the first electric power to the plurality of electric motors to perform flight using the plurality of rotors. unmanned aircraft.

2. The unmanned aerial vehicle described in claim 1, wherein when the control device detects the abnormality while controlling the multiple electric motors to fly while supplying the second power to the work machine, it stops supplying the second power to the work machine, maintains supply of the first power to the multiple electric motors to continue flight using the multiple rotors, and then reduces the rotational speed of the multiple rotors to land the unmanned aerial vehicle.

3. the plurality of rotors are a plurality of first rotors; at least one second rotor; an internal combustion engine driving the at least one second rotor; a power generation device driven by the internal combustion engine to generate third electric power; a battery that stores the third power; Furthermore, the power source includes the power generator and the battery; the control device monitors the state of at least one of the internal combustion engine, the power generation device, the second rotor, a power transmission system to the second rotor, and a fuel supply system to the internal combustion engine, and when an abnormality in the at least one state is detected, stops the supply of the second electric power to the work machine, maintains the supply of the first electric power to the plurality of electric motors, stops the at least one second rotor, and performs flight using the plurality of first rotors.

3. The unmanned aerial vehicle according to claim 1 or 2.

4. Further, a battery management device is provided to control charging and discharging of the battery. The unmanned aerial vehicle described in claim 3, wherein the battery management device maintains the battery charge rate at a value higher than a threshold required for continuing flight by the multiple first rotors and then landing if the abnormality is detected while flight by the multiple first rotors and the at least one second rotor is being performed with the work machine powered by the second power.

5. the control device acquires information indicating a weight of the work machine, and changes the threshold value of the charging rate in accordance with the weight. The unmanned aerial vehicle according to claim 4.

6. Further, at least one sensor is provided that outputs sensor data for detecting an abnormality in the device; The control device detects an abnormality in the device based on the sensor data.

3. The unmanned aerial vehicle according to claim 1 or 2.

7. A control system for an unmanned aerial vehicle including a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a coupling device that couples a work machine that performs ground work, a control device that controls the supply of a first electric power from the power source to the plurality of electric motors and the supply of a second electric power from the power source to the work machine, and that controls the operation of the plurality of electric motors; When the control device detects an abnormality in a device included in the unmanned aerial vehicle, the control device stops the supply of the second electric power to the work machine and maintains the supply of the first electric power to the plurality of electric motors to perform flight using the plurality of rotors. Control system.

8. A control method for an unmanned aerial vehicle including a plurality of rotors, a plurality of electric motors that respectively drive the plurality of rotors, a power source, and a coupling device that couples a work machine that performs ground work, the method comprising: controlling a supply of a first electric power from the electric power source to the plurality of electric motors and a supply of a second electric power from the electric power source to the working machine; controlling the operation of the plurality of electric motors; Detecting an abnormality in a device included in the unmanned aerial vehicle; When the abnormality is detected, stopping the supply of the second electric power to the work machine and maintaining the supply of the first electric power to the plurality of electric motors to perform flight using the plurality of rotors; A control method comprising: