Agricultural flight device

Abstract

Provided is an agricultural flight device capable of continuing stable flight even when a load weight rapidly drops.　An agricultural flight device (5) is provided with an airframe (50a), a rotary wing (50c) provided on the airframe (50a), and a holding device (51) provided on the airframe (50a) and capable of changing the state thereof between a holding state for holding a material (S) and a release state for releasing the material (S). The rotational speed of the rotary wing (50c) decreases when the holding device (51) transitions from the holding state to the release state.

Description

Agricultural flying device 【0001】 The present invention relates to an agricultural flying device for transporting materials. 【0002】 The transport aircraft disclosed in Patent Document 1 flies while holding a seedling tray, and supplies the seedling tray to the seedling tray carrier of the seedling transplanter by dropping the seedling tray in a state of approaching above the seedling tray carrier of the seedling transplanter. 【0003】 Japanese Patent Publication "Japanese Patent Application Laid-Open No. 2022-57029" 【0004】 In the transport aircraft of Patent Document 1, when the holding of the seedling tray is released, there is a problem that the aircraft may rise due to a sudden decrease in the loading weight, resulting in unstable flight. 【0005】 Therefore, in view of the above problems, an object of the present invention is to provide an agricultural flying device that can continue stable flight even when the loading weight suddenly decreases. 【0006】 The technical means of the present invention for solving the above technical problems is characterized by the following points. 【0007】 An agricultural flying device according to an aspect of the present invention includes an airframe, a rotor provided on the airframe, and a holding device provided on the airframe and capable of changing between a holding state of holding a material and a releasing state of releasing the material. When the holding device shifts from the holding state to the releasing state, the rotational speed of the rotor decreases. 【0008】 According to the present invention, the agricultural flying device can continue stable flight even when the loading weight suddenly decreases. 【0009】This is a schematic diagram of a material transport system. This is a block diagram of a material transport system. This is a side view of a rice transplanter. This is a diagram illustrating the supply of seedlings to a moving implement by an agricultural flying device. This is a rear view of a seedling supply device and seedling stand. This is an overall perspective view of the agricultural flying device. This is a diagram of an agricultural flying device that has taken off upwards while holding seedlings (seedling mats). This is a side view of a work vehicle showing an example of altitude according to the stages in the flight path of the agricultural flying device. This is a diagram showing the rotation speed of the rotor blades and the altitude of the aircraft when dropping material (seedling mats). This is a diagram showing the rotation speed of the rotor blades and the altitude of the aircraft when dropping material (granules). This is a diagram of an agricultural flying device that has a holding device to hold a container of granules. This is a flowchart showing an example of control setting processing according to the type of material and the number of times it is dropped. This is a flowchart showing another example of control setting processing. This is a diagram showing an example of a memory table showing the relationship between material weight and the amount of decrease in rotation speed. This is a diagram showing an example of a setting screen displayed on a mobile terminal. This is a diagram showing an example of a setting screen displayed on a mobile terminal. This is a flowchart showing an example of rotor blade rotation speed reduction control processing. This diagram shows the rotor speed and aircraft altitude during multiple drops of materials (seedling mats). 【0010】 The following describes one embodiment of the present invention with reference to the drawings. Figure 1 is a schematic diagram of the material transport system SY. Figure 2 is a block diagram of the material transport system SY. 【0011】 As shown in Figures 1 and 2, the material transport system SY comprises a server 70 and an agricultural flying device 5. The agricultural flying device 5 carries agricultural materials S (for example, seedling mats such as seedling mats M) by flight and replenishes the materials S to the working machine 1 while it is moving. 【0012】 Material S is not limited to seedling mats, but may also be plant mats on which plants such as vegetable seedlings or scions have been grown. Material S (agricultural material) may also be granules, liquids, or seeds placed in a container 51A shown in Figure 11, which can be transported by the agricultural flying device 5. For example, granules include formulations of pesticides processed into granules. Liquids include liquid fertilizers for improving the soil environment and liquid pesticides for controlling pests and diseases. 【0013】The implement 1 is, for example, a rice transplanter 10. Figure 3 is a side view of the rice transplanter 10. As shown in Figures 1 and 3, the rice transplanter 10 comprises a body 11, a prime mover 12, a transmission 13, and a seedling planting device 18. The prime mover 12 and the transmission 13 are mounted on the body 11. The rice transplanter 10 is, for example, four-wheel drive, and the power shifted by the transmission 13 is transmitted to the left and right front wheels 14F and the left and right rear wheels 14R. For this reason, the body 11 is supported so that it can move on the left and right front wheels 14F and the left and right rear wheels 14R. The seedling planting device 18 is mounted at the rear of the body 11. The seedling planting device 18 takes seedlings loaded on a seedling tray 41, which is mounted at the rear of the body 11, from the seedling tray 41 and plants them in a field or the like. 【0014】 As shown in Figure 2, the rice transplanter 10 includes a control device 30 and a storage unit 31. The storage unit 31 is a storage device such as a non-volatile memory, and stores various control programs, various data, etc. The storage unit 31 is, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive). 【0015】 The control device 30 is composed of electrical and electronic circuits, a processor, memory, etc. The processor is, for example, a CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), and ASIC (Application Specific Integrated Circuit). The control device 30 controls the operation of each part of the rice transplanter 10 by having the processor execute a control program. For example, the control device 30 controls the prime mover 12 and the transmission 13, etc. The control device 30 controls the travel system and work system of the rice transplanter 10 based on operation signals when operating the operating tools (operating levers, operating switches, operating volumes, etc.) installed around the driver's seat 15, detection signals from various sensors mounted on the vehicle body 11, etc. 【0016】As shown in Figure 2, the rice transplanter 10 is equipped with a position detection device 32 (for example, a positioning device 32A) that detects its own position. The positioning device 32A is, for example, located on the front side of the rice transplanter 10 (vehicle body 11). The positioning device 32A is a device that detects its own position (latitude, longitude) based on data from positioning satellites such as GPS and Michibiki (positioning satellite system). The positioning device 32A may also have inertial devices such as an acceleration sensor to detect acceleration and a gyro sensor to detect angular velocity, and may correct its position using the acceleration and angular velocity detected by the inertial devices, or it may correct its position using other correction signals, etc., and is not limited to these. 【0017】 The rice transplanter 10 is equipped with a surrounding monitoring device 33 for monitoring its surroundings. The surrounding monitoring device 33 may be, for example, an imaging device 33A, but it may also be LiDAR (Light Detection and Ranging), ultrasonic sonar, etc. The imaging device 33A is, for example, a visible light camera and is capable of imaging the area around the rice transplanter 10. The imaging device 33A is located at the front of the rice transplanter 10, but is not limited to this location. For example, the imaging device 33A may be located near the driver's seat 15, allowing the driver seated in the driver's seat 15 to image the area around the rice transplanter 10 from their line of sight. The images captured by the imaging device 33A are used for autonomous operation. 【0018】 Figure 4 is a diagram illustrating the supply of seedlings to the working machine 1 while it is in motion using the agricultural flying device 5. The memory unit 31 stores a pre-set planned route L1 for driving the rice transplanter 10. The control device 30 has a processor that executes an automatic steering control program. The control device 30 automatically changes the driving speed of the vehicle body 11 and steers the vehicle body 11 (for example, changes the steering direction of the front wheels 14F) so that its own position (position of the vehicle body 11) detected by the positioning device 32A matches the planned route L1. In addition, the control device 30 can also perform automatic driving so that the position of the vehicle body 11 matches the planned route L1 based on the position of the vehicle body 11, the image captured by the imaging device 33A, and the planned route L1, by having the processor execute an automatic driving control program. 【0019】For example, the rice transplanter 10 (working device 1) is equipped with, for example, an automatic steering mechanism 17. In automatic steering mode, the rice transplanter 10 (working device 1) is driven by automatic steering using the automatic steering mechanism 17 so that its position follows the planned travel path L1 (more precisely, the straight-ahead path L11 described later). In automatic driving mode, the rice transplanter 10 (working device 1) is driven by automatic driving (autonomous driving) through control of the driving system by the control device 30 (including control of the automatic steering mechanism 17) so that its position follows the planned travel path L1 (the straight-ahead path L11 and turning path L12 described later). 【0020】 The rice transplanter 10 (working device 1) may be operated manually. When operated manually, the operator sits in the driver's seat 15 and steers the rice transplanter 10 by operating the steering wheel 16. Alternatively, the rice transplanter 10 (working device 1) may be operated automatically (automatic steering or automatic driving) as described above. When operated automatically, the rice transplanter 10 (working device 1) operates automatically based on the vehicle position detected by the positioning device 32A and the planned driving route L1. 【0021】 As shown in Figure 2, the rice transplanter 10 has a communication device 34. The communication device 34 is a communication module that communicates with the server 70 either directly or indirectly, and can perform wireless communication using, for example, the IEEE 802.11 series communication standards such as Wi-Fi (Wireless Fidelity, registered trademark), BLE (Bluetooth® Low Energy), LPWA (Low Power, Wide Area), and LPWAN (Low-Power Wide-Area Network). The communication module has a communication chip and / or a communication circuit. The communication device 34 can also perform wireless communication using, for example, a mobile phone network or a data communication network. 【0022】The memory unit 31 stores information related to the rice transplanter 10. The information related to the rice transplanter 10 includes the travel position (latitude, longitude) of the rice transplanter 10 detected by the positioning device 32A, time information indicating the time at that travel position, and travel information of the rice transplanter 10 for each travel position (travel direction, travel speed, etc.). In addition, the information related to the rice transplanter 10 may also include work information of the seedling planting device 18 and state information such as captured images taken by the imaging device 33A. 【0023】 The communication device 34 sequentially transmits information about the rice transplanter 10 stored in the memory unit 31 to the server 70. For example, the communication device 34 transmits information about the rice transplanter 10 periodically (every few seconds, every few hundred milliseconds) and whenever an event occurs to the server 70. Specifically, since the communication device 34 performs telematics communication, it transmits to the server 70 the position of the rice transplanter 10, the travel information of the rice transplanter 10 (travel direction, travel speed, etc.), the work information of the seedling planting device 18, and status information such as captured images taken by the imaging device 33A, in association with each other. 【0024】 Next, the agricultural flying device 5 will be described. Figure 6 is an overall perspective view of the agricultural flying device 5. As shown in Figures 1 and 6, the agricultural flying device 5 is, for example, a multicopter 50, and is configured to hold and transport seedling mats M by flight. The multicopter 50 is an aircraft (for example, an unmanned aircraft) also known as a drone. 【0025】 Specifically, the multicopter 50 includes a body 50a, an arm 50b provided on the body 50a, a rotor 50c provided on the arm 50b, and a pair of skids 50d provided on the body 50a. The rotor 50c is a device that generates lift for flight and includes a rotor that provides rotational force and blades (propellers) that rotate by the drive of the rotor. The rotor 50c includes a rotation speed detection sensor that detects the rotation speed of the rotor. The rotation speed detection sensor detects the rotation speed of the rotor 50c. Alternatively, the rotor 50c may detect the rotation speed of the rotor based on a control signal (drive voltage) that rotates the rotor. 【0026】The multicopter 50 has an imaging device 50e. The imaging device 50e is, for example, an infrared camera, a visible light camera, etc., and is capable of imaging the area around the multicopter 50. 【0027】 The multicopter 50 may be equipped with at least one of the following: an angular velocity (gyro) sensor for detecting the attitude and movement of the aircraft 50a; an acceleration sensor for detecting the speed of the aircraft 50a; an inertial measurement unit (IMU) for detecting the attitude and speed of the aircraft 50a; a barometric pressure sensor for detecting the altitude of the multicopter 50; an ultrasonic sonar (or ultrasonic sensor) for detecting the position of surrounding objects; a LiDAR (Light Detection and Ranging) for measuring objects using laser light; and a magnetic compass sensor for detecting direction. In this embodiment, the multicopter 50 is equipped with, for example, an inertial measurement unit and a magnetic compass sensor. 【0028】 As shown in Figure 2, the multicopter 50 is equipped with a control device 50f that controls various operations of the multicopter 50. The control device 50f is connected to the above-mentioned sensors (magnetic orientation sensor, inertial measurement device, rotation speed detection sensor, etc.), position detection device 55g, communication device 50i, and memory unit 50h. Based on the detection values ​​of the multiple sensors and instructions from the server 70, the control device 50f controls the rotor blades 50c, communication device 50i, memory unit 50h, and holding device 51. The control device 50f is composed of electrical and electronic circuits, a processor, memory, etc. The processor is, for example, a CPU, GPU, DSP, FPGA, and ASIC. The multicopter 50 functions as a control device 50f when the processor executes a control program. 【0029】The multicopter 50 has a position detection device 50g that detects its own position. The position detection device 50g is a device that detects its own flight position (latitude, longitude, altitude), that is, the flight position (latitude, longitude, altitude) of the multicopter 50 (aircraft 50a), based on data from positioning satellites such as GPS and Michibiki (positioning satellite system). Its own position includes the flight position during flight and the landing position during landing. The position detection device 50g detects the flight height (i.e., altitude) of the multicopter 50 (aircraft 50a), but the altitude of the multicopter 50 (aircraft 50a) may also be detected by using various sensors such as an altimeter, ultrasonic sonar, and LiDAR, either alone or in conjunction with other sensors. 【0030】 The multicopter 50 is equipped with a storage unit 50h for storing various data, programs, etc. The storage unit 50h is, for example, a non-volatile storage device, such as an HDD or SSD. The storage unit 50h stores information about the multicopter 50 periodically (every few seconds, every few hundred milliseconds) and each time an event occurs. The information about the multicopter 50 includes the flight position (latitude, longitude, altitude) of the multicopter 50 (aircraft 50a), time information indicating the time at that flight position, flight information of the multicopter 50 for each flight position (flight direction, flight speed, etc.), and the rotation speed of the rotor blades 50c at that flight position. The flight direction is detected by a magnetic direction sensor, and the flight speed is detected by an inertial measuring device. The position detection device 50g may calculate the flight direction and flight speed based on the multiple flight positions it has detected. Furthermore, information regarding the multicopter 50 may include operational information indicating whether or not the seedling mat M is being held (operational information indicating whether or not it is being held by the holding device 51 described later), the rotation speed of the rotor blades 50c detected by the rotation speed detection sensor, and status information such as images captured by the imaging device 50e. 【0031】The multicopter 50 has a communication device 50i that can communicate with the server 70. The communication device 50i is a communication module that can communicate with the server 70 either directly or indirectly, and can perform wireless communication using, for example, the IEEE 802.11 series communication standards such as Wi-Fi®, BLE, LPWA, LPWAN, etc. The communication module has a communication chip and / or a communication circuit. The communication device 50i can also perform wireless communication using, for example, a mobile phone network or a data communication network. 【0032】 The communication device 50i transmits information about the multicopter 50 stored in the memory unit 50h to the server 70. In other words, the communication device 50i transmits information about the multicopter 50 to the server 70 periodically (every few seconds, every few hundred milliseconds) and whenever an event occurs. For example, the communication device 50i performs telematics communication. The communication device 50i transmits to the server 70 the flight position of the multicopter 50, flight information (flight direction, flight speed, etc.), work information indicating whether or not the seedling mat M is being held (work information indicating the separation or approach state of the holding device 51, described later), and status information such as the captured image taken by the imaging device 50e and the detection state of the detection device 56, described later, in association with each other. 【0033】 The seedling mat M, which is to be transported by the multicopter 50, is rectangular in plan view in order to fit into the material loading section 24 (see Figure 5) of the rice transplanter 10, which will be described later. As shown in Figure 3, it has a long side Ma and a short side Mb. The seedling mat M consists of numerous seedlings Se, each of which has grown with its leaves and stem positioned on top of its roots in the soil So. As shown in Figure 4, the seedling storage area is the place where the seedling mat M was placed before transport, for example, the ridge SH around the field F. 【0034】 As shown in Figures 1 and 6, the multicopter 50 has a holding device 51 (seedling holding device) for holding seedlings. For example, the holding device 51 is located at the bottom of the aircraft body 50a. The multicopter 50 transports seedlings by flying with the holding device 51 holding the seedlings. 【0035】The holding device 51 grips at least a portion of the leaves and stems of the seedling Se. For example, if a seedling Se is present between a pair of gripping members 52 and 53, the holding device 51 brings the pair of gripping members 52 and 53 closer together, creating a holding state in which the seedling Se in the seedling mat M is held by the pair of gripping members 52 and 53. The holding device 51 also releases the material S (seedling mat M) by separating the pair of gripping members 52 and 53 from the holding state in which the seedling Se in the seedling mat M is held. 【0036】 Specifically, the holding device 51 includes a pair of clamping members 52 and 53 capable of clamping the leaves or stems of seedlings, and a moving mechanism 54 that changes the distance between the pair of clamping members 52 and 53. For example, the moving mechanism 54 includes a first mechanism M1 that brings the pair of clamping members 52 and 53 closer together so that they can clamp the leaves or stems of seedlings, and a second mechanism M2 that separates the pair of clamping members 52 and 53. The holding device 51 includes a detection device 56 that detects the presence or absence of seedlings Se between the pair of clamping members 52 and 53. The detection device 56 is one of various sensors that detect the presence or absence of seedlings Se, and may include, for example, a photoelectric sensor or a laser sensor. 【0037】 Here, we will describe the actions of the multicopter 50 from moving to the seedling placement area, to taking hold of the seedling mat M at the seedling placement area, and flying upwards. 【0038】 The multicopter 50 flies to the seedling placement location shown in Figure 4 based on positional information indicating the seedling placement location and its own flight position (latitude, longitude, altitude) detected by the position detection device 50g. The multicopter 50 reaches above the seedling mat M at the seedling placement location shown in Figure 4 and descends when the holding device 51 is in a position where it overlaps with the seedling Se in a plan view. 【0039】 The multicopter 50 descends until the gripping members 52 and 53 overlap with the seedling Se in a direction perpendicular to the vertical direction. Once the descent is complete, the leaves or stems of the seedling Se are positioned between the pair of gripping members 52 and 53, causing the gripping members 52 and 53 to hold the seedling Se. 【0040】The holding device 51 holds at least a part of the leaves and stems of the seedling Se. That is, when the seedling Se is present between the pair of holding members 52 and 53, the first mechanism M1 brings the pair of holding members 52 and 53 closer to each other so that the pair of holding members 52 and 53 are in a holding state (a close state) of holding the seedling Se on the seedling mat M. 【0041】 As shown in FIG. 7, with the holding device 51 holding at least a part of the leaves and stems of the seedling Se (in this embodiment, the tip side of the leaves of the seedling Se), the agricultural flying device 5 is lifted to lift the seedling Se. 【0042】 Next, the server 70 shown in FIG. 2 will be described. The server 70 is, for example, a fixed computer installed in a farm household, a farming company, an agricultural machinery manufacturer, agricultural services, etc., or a portable computer that can be carried by an administrator, an operator, etc. In this embodiment, the server 70 is a fixed computer. 【0043】 The server 70 includes a communication device 71 that can communicate with the rice transplanter 10 and the multicopter 50. The communication device 71 is a communication module that performs either direct communication or indirect communication with the rice transplanter 10 and the multicopter 50. For example, it performs wireless communication according to communication standards such as Wi-Fi (registered trademark) of the IEEE 802.11 series, BLE, LPWA, LPWAN, etc. The communication module has a communication chip and / or a communication circuit. Also, the communication device 71 can perform wireless communication, for example, via a mobile phone communication network or a data communication network. 【0044】 The server 70 includes a remote control device 72 that remotely controls the multicopter 50. The remote control device 72 is composed of an electric / electronic circuit, a processor, a memory, etc. The processor is, for example, a CPU, a GPU, a DSP, an FPGA, and an ASIC, etc. The server 70 functions as the remote control device 72 when the processor executes a remote control program for the multicopter 50. 【0045】The remote control device 72 transmits remote control signals to the multicopter 50 via the communication device 71. The multicopter 50 operates according to the remote control signals from the remote control device 72. For example, based on the remote control signals from the remote control device 72, the multicopter 50 heads towards the seedling storage area, picks up seedlings from the storage area, transports them by flight, and replenishes the seedlings to the moving implement 1. In addition, a receiving platform 90 (seedling receiving platform) is provided on the rear side of the rice transplanter 10 (vehicle body 11), as shown in Figures 1 and 3. The receiving platform 90 is located behind the positioning device 32A on the rice transplanter 10. The multicopter 50 can drop seedlings onto the receiving platform 90 of the moving rice transplanter 10 according to the remote control signals from the remote control device 72. 【0046】 Furthermore, when the multicopter 50 transports seedlings to replenish the rice transplanter 10, the imaging device 50e captures images of the seedling mat (seedlings) at the seedling placement site, and based on the captured images of the seedling mat (seedlings), it moves to a position above the seedling mat (seedlings) and holds the seedling mat (seedlings) based on the captured images. In addition, when the multicopter 50 is heading towards the rice transplanter 10 to be replenished, it tracks the rice transplanter 10 based on images of the rice transplanter 10, and drops the seedling mat onto the receiving platform 90 based on images of the receiving platform 90 of the rice transplanter 10. 【0047】 The server 70 is equipped with a storage unit 73. The storage unit 73 is a non-volatile storage device, such as an HDD or SSD. The storage unit 73 includes a map data storage unit 73A that stores various data (information). The map data storage unit 73A stores, for example, agricultural map data. Agricultural map data is data that associates agricultural data with location. Agricultural data includes field map data, machine data, work data, etc. 【0048】The field map data is map data that associates map data including a pre-registered field with a predetermined planned travel route L1 of the rice transplanter 10 (working machine 1) in the field. The map data includes the outer shape of the field, the area of the field, the positions of the entrances and exits of the field, the positions of the seedling placement locations prepared in the surrounding areas of the field, and the like. Note that the travel route may be, for example, the actual travel route when the working machine 1 travels so as to match the planned travel route L1. 【0049】 The machine data is various data related to machines for agriculture, and is, for example, control data or operation data for operations such as steering and traveling in the field in agricultural vehicles such as tractors, rice transplanters, transplanters, harvesters such as combines, fertilizer applicators, chemical sprayers, forming machines, lawn mowers, preparation machines, tillers, and the like. 【0050】 The work data is data related to the work performed by the working machine 1 (machine for agriculture) in the field, and is the amount of transplantation, the amount of fertilization, the amount of chemical spraying, the amount of seeding, etc. in the field. For example, in the case of the work data of the rice transplanter 10 (that is, data indicating the amount of seedling transplantation in the field), the amount of transplantation of the seedlings planted by the seedling planting device 18 in the field is stored as the work data. The amount of transplantation is the number of planting rows individually set for the rice transplanter 10, and is, for example, the number of rows such as 3 rows, 4 rows, 5 rows, 8 rows, 10 rows, etc. Note that the storage unit 31 may store the planned amount of transplantation to be planted by the seedling planting device 18 as the work data when it is planned to perform rice transplanting work with the rice transplanter 10. 【0051】 The server 70 includes a display control unit 74. The server 70 functions as the display control unit 74 when the processor executes a display control program. The display control unit 74 can control the display on the display unit 66 of the mobile terminal 61 connected to the server 70. For example, the display unit 66 can display an agricultural map transmitted from the server 70 by the display control unit 74, or display the status of seedling replenishment to the traveling rice transplanter 10 by the multicopter 50 described later. 【0052】 Here, the rear configuration of the rice transplanter 10, that is, the configuration such as the seedling planting device 18 will be described using FIGS. 3 and 5. FIG. 5 is a rear view of the seedling supply device 20 and the seedling mounting table 41. 【0053】 As shown in Figure 3, the rice transplanter 10 is equipped with a seedling supply device 20 that supplies a seedling mat M to the seedling planting device 18 (seedling tray 41). The rice transplanter 10 is a transplanting machine that cuts a predetermined amount of seedlings from the seedling mat M placed on the seedling tray 41 and plants the cut seedlings in the field (paddy field). 【0054】 In Figure 3, the direction of arrow AW1 is described as the front (forward of the aircraft), the direction of arrow AW2 is described as the rear (rear of the aircraft), and the direction of arrow AW3 is described as the front-to-back direction (front-to-back direction of the aircraft). Also, the near side of Figure 3 is described as the left, and the far side of Figure 3 is described as the right. Furthermore, the horizontal direction, which is perpendicular to the front-to-back direction (arrow AW3), is described as the aircraft width direction (see aircraft width direction K1 in Figure 5). 【0055】 As shown in Figure 3, a seedling planting device 18 is provided at the rear of the vehicle body 11. The seedling planting device 18 is connected to the vehicle body 11 via a link mechanism 19 and a connecting body 28 so as to be able to move up and down. The seedling planting device 18 is also driven to move up and down by a hydraulic cylinder 21. 【0056】 As shown in Figure 3, the seedling planting device 18 includes a seedling tray 41 on which a seedling mat M is placed, a planting mechanism 22 that cuts a predetermined amount of seedlings from the seedling mat M placed on the seedling tray 41 and plants them in the field (paddy field), and a float 23 that performs leveling of the field surface. As shown in Figure 3, the seedling tray 41 is provided in a sloping shape that moves forward as it goes upward (a forward-sloping shape). 【0057】 As shown in Figure 5, the seedling tray 41 has a plurality of material placement sections 24 (seedling placement sections) arranged in the machine width direction K1 on which seedling mats M are placed. Partition guides 25 are provided on both sides of the material placement section 24 in the machine width direction K1. The seedling mat M is placed in each material placement section 24 with its long side Ma aligned with the inclination direction of the seedling tray 41 and its short side Mb aligned with the machine width direction K1. Two seedling mats M can be placed side by side in the inclination direction of the seedling tray 41 in each material placement section 24. The seedling mats M on the material placement section 24 can be moved vertically downward along the material placement section 24 by a vertical feeding mechanism 26. 【0058】 As shown in Figure 3, the seedling tray 41 is supported by the connecting body 28 so as to be movable in the width direction K1 by the connecting body 28 by the upper guide portion 27A and the lower guide portion 27B provided on the connecting body 28, and is driven to move back and forth in the width direction K1 by the lateral feeding mechanism 84 (see Figure 5) provided on the connecting body 28. 【0059】 The planting mechanisms 22 are arranged in a number corresponding to the number of planting rows, spaced apart in the machine width direction K1. In this embodiment, since the rice transplanter 10 is an 8-row planter, eight planting mechanisms 22 are provided, corresponding to the number of material loading sections 24. The planting mechanisms 22 are supported by a connecting body 28. Therefore, the planting mechanisms 22 move relative to the seedling tray 41. In other words, the seedling tray 41 moves in the machine width direction K1 relative to the planting mechanisms 22. The planting mechanisms 22 take out a predetermined amount of seedlings from the lower end of the seedling mat M placed on the seedling tray 41 (material loading section 24) which moves back and forth in the machine width direction K1, and plant them. More specifically, the planting mechanisms 22 rotate around an axis extending in the machine width direction K1, and take out one seedling (a predetermined amount) from the lower end of the seedling mat M placed on the material loading section 24 and plant it in the field. Then, while the seedling tray 41 is moving in one direction in the width direction K1 of the machine body, the planting mechanism 22 cuts off a horizontal row of seedlings at the lower end of the seedling mat M. Once the horizontal row of seedlings at the lower end of the seedling mat M is cut off, the seedling mat M is moved vertically by the vertical feeding mechanism 26 by the amount corresponding to the horizontal row that was cut off, and the seedling tray 41 moves in the other direction in the width direction K1 of the machine body (opposite to the aforementioned one), and the same planting operation as above is performed. In other words, the seedling tray 41 is driven back and forth in the width direction K1 of the machine body by the width of the seedling mat M, and the seedling mat M is moved vertically each time the seedling tray 41 is at the end of its reciprocating movement. 【0060】 As shown in Figures 1 and 5, the rice transplanter 10 is equipped with a receiving platform 90 that receives seedling mats M dropped from the multicopter 50. Specifically, as shown in Figures 3 and 5, the seedling supply device 20 that supplies seedling mats M to the seedling tray 41 has a support bracket 91 attached to the upper part of the seedling tray 41 and a seedling supply tray 92 supported by the support bracket 91. 【0061】The seedling supply stand 92 may be equipped with markers (identification images) at one or more locations. The multicopter 50 controls its flight position when approaching the support stand 90 and its flight position when aligning itself directly above the support stand 90, based on the position and size of the markers included in the image captured by the imaging device 50e. The seedling supply stand 92 may also be equipped with guidance devices that emit guidance signals at one or more locations. The multicopter 50 may control its flight position based on the guidance signals. 【0062】 The seedling supply stand 92 is provided on the seedling tray 41 via a support bracket 91. By providing the seedling supply stand 92 on the seedling tray 41, the seedling supply stand 92 (seedling supply device 20) reciprocates together with the seedling tray 41 in the machine width direction K1. In other words, the seedling supply stand 92 (receiving stand 90) is movable in the lateral direction (machine width direction K1) of the rice transplanter 10. As shown in Figure 5, the receiving stand 90 is movable in the lateral direction (machine width direction K1) while ensuring that it is positioned on the centerline of the lateral direction (machine width direction K1) of the rice transplanter 10. In other words, even when the receiving stand 90 is moved in the machine width direction K1, it is ensured that it is positioned on the centerline of the lateral direction of the rice transplanter 10. 【0063】 As shown in Figures 3 and 5, the seedling supply platform 92 is the area on which the seedling mats M, which have been transported by multicopter 50, are placed. More specifically, the seedling mats M are placed on the seedling supply platform 92 by being dropped from the multicopter 50. The seedling supply platform 92 then sends the placed seedling mats M to the seedling tray 41. In other words, the seedling supply platform 92 receives the seedling mats M dropped by the multicopter 50 and sends these received seedling mats M to the seedling tray 41. Here, the multicopter 50 drops the seedling mats M during flight, placing them on the seedling supply platform 92. When dropping the seedling mats M from the multicopter 50 onto the seedling supply platform 92, the seedling supply platform 92 is in a horizontal position P1, as shown in Figures 3 and 5. 【0064】As shown in Figure 3, the seedling mat M is placed on the seedling supply stand 92 with its long side Ma aligned with the front-to-back direction (arrow AW3), and as shown in Figure 5, with its short side Mb aligned with the machine width direction K1. 【0065】 The timing for starting the supply of seedling mats M to the rice transplanter 10 by the multicopter 50 (hereinafter sometimes referred to as the start timing) may be, for example, the time when a seedling depletion sensor mounted on the rice transplanter 10 detects that seedling mats M should be supplied to the seedling tray 41. The seedling depletion sensor is provided on each material placement section 24 of the seedling tray 41 and is a sensor that detects when the amount of seedlings remaining (material remaining) in the seedling mats M, which are placed on the material placement sections 24 and from which seedlings are cut by the planting mechanism 22, falls below a predetermined level. The seedling depletion sensor can be any configuration, not limited to a contact sensor, as long as it can detect the amount of seedlings remaining in the seedling mats M placed on the material placement sections 24. Alternatively, a detection device consisting of a camera and an image diagnostic device may be used to detect when the amount of seedlings remaining in the seedling mats M falls below a predetermined level. In this case, the camera photographs the seedling mat M placed on the material loading section 24, and the image diagnostic device analyzes the image of the seedling mat M taken by the camera to detect the remaining amount of seedlings in the seedling mat M placed (planted) on the material loading section 24. 【0066】 Furthermore, as a simpler method for detecting when the remaining number of seedlings in the seedling mat M falls below a predetermined level, the system may detect only whether the seedlings in the seedling mat M are present within a specific area of ​​the material placement section 24. By analyzing images to determine only whether there are no seedlings within the specific area, it may be possible to determine that the remaining number of seedlings is below a certain level and may require replenishment. 【0067】 Furthermore, the amount of seedlings remaining in the seedling mat M on the material loading section 24 varies for each material loading section 24 depending on the field conditions. Therefore, the timing of supplying (replenishing) the seedling mat M differs for each material loading section 24. 【0068】Furthermore, the start timing for seedling replenishment by the multicopter 50 may be a timing calculated by the server 70. For example, the server 70 may pre-calculate the start timing for seedling replenishment by the multicopter 50 based on the relationship between the planned travel route L1 of the rice transplanter 10, the seedling consumption rate (material consumption rate) along the planned travel route L1 of the rice transplanter 10, and the capacity of the seedling mat M of the seedling planting device 18 (initial setting capacity, or current remaining amount), which are pre-stored in the memory unit 73. 【0069】 The server 70 may also obtain the start timing for seedling replenishment from the work plan (seedling planting plan) stored in the storage unit 73. The work plan (seedling planting plan) includes the planned travel route L1 of the rice transplanter 10 and instruction information for seedling replenishment by the multicopter 50. The instruction information for seedling replenishment includes the start timing (start time) of seedling replenishment from the start of work on the planned travel route L1 and the target point (latitude, longitude, altitude) set on the planned travel route L1. 【0070】 As shown in Figure 5, the seedling supply stand 92 has a delivery unit 100. The delivery unit 100 is movable in the front-rear direction (arrow AW3), and can move the seedling mat M, which has been adjusted in the machine width direction K1, to the rear and send the seedling mat M to the material loading section 24. 【0071】 In the seedling supply device 20 described above, when it is detected that the remaining amount of seedlings in the seedling mat M on the material loading section 24 has fallen below a predetermined level, the seedling mat M is transported by the multicopter 50 and placed on the seedling supply stand 92 via the multicopter 50. At this time, the seedling supply stand 92 is kept in a horizontal position P1. Once the seedling mat M is placed on the seedling supply stand 92, the adjustment mechanism adjusts (corrects) the misalignment of the seedling mat M in the machine width direction K1, and aligns the seedling mat M to a position corresponding to the material loading section 24 to which the seedling mat M should be supplied. 【0072】 Next, the seedling supply stand 92 is changed from a horizontal position P1 to an inclined position P2, and the dispensing body 100 is moved toward the material loading section 24, causing the seedling mat M to move toward the material loading section 24 and be supplied to the material loading section 24. 【0073】Here, we will explain, using Figure 4, how the multicopter 50 (agricultural flying device 5) is supplying seedling mats M (seedlings Se) to the moving rice transplanter 10 (working machine 1). Figure 4 is a diagram illustrating the supply of seedlings to the moving working machine 1 by the agricultural flying device 5. 【0074】 As shown in Figure 4, the rice transplanter 10 travels in such a way that the vehicle position detected by the positioning device 32A matches the planned travel route L1. The planned travel route L1 includes a plurality of parallel straight paths L11 and a turning path L12 that connects the same-side ends of two straight paths L11. 【0075】 As shown in Figure 4, the multicopter 50 flies along a global path. The global path is the route connecting the departure point and the target point when the multicopter 50 flies automatically (including remote flight and autonomous flight). As shown in Figure 4, the global path is the route connecting the seedling storage area and the working machine 1 that is currently moving, and is divided into an outbound route (the route to replenish the seedlings) and a return route (the route to return from replenishing the seedlings). The outbound route is the route connecting the departure point of the multicopter 50 (for example, the seedling storage area) to the target point (for example, the point above the support platform 90 of the working machine 1 that is currently moving). The return route is the route from the target point back to the departure point. 【0076】 In this embodiment, the server 70 generates global routes and stores them in the storage unit 73. For example, the server 70 is equipped with a processing unit 77 that performs route planning, and this processing unit 77 generates global routes. Generating global routes is sometimes called global path planning or global route design. The server 70 functions as a processing unit 77 by having a processor execute a route planning calculation program. Alternatively, the multicopter 50 or the mobile terminal 61 may be equipped with the above-mentioned processing unit and generate global routes in the multicopter 50 or the mobile terminal 61. 【0077】A local path is a path that is sequentially generated when the multicopter 50 flies automatically (including remote flight and autonomous flight) along a global path, and includes a local path for following and catching up with the rice transplanter 10 from behind (the path shown as "Seedling Replenishment" in Figure 4), or a local path that can avoid obstacles. Generating a local path is sometimes called local path planning or local path design. Local paths are sequentially generated while the multicopter 50 is flying, based on data acquired by one or more sensing devices (e.g., imaging device 50e) on the multicopter 50. 【0078】 In this embodiment, the processing unit 77 of the server 70 generates global routes and local routes, but is not limited to this. The server 70 may also have a processing unit for local routes in addition to the processing unit for global routes. Alternatively, a control device 30 mounted on the work machine 1 or a multicopter 50 may be equipped with a processing unit for local routes. For example, a management device (e.g., server 70) that manages agricultural work by agricultural machinery (e.g., work machine 1) may generate global routes, and a control device 30 or multicopter 50 mounted on the work machine 1 may generate local routes. 【0079】 In this embodiment, the server 70 remotely controls the multicopter 50. Specifically, the remote control device 72 of the server 70 remotely controls the multicopter 50 based on the field map data (including the planned travel route L1) and global route stored in the storage unit 73, and information about the rice transplanter 10 and information about the multicopter 50 that are sequentially received by the communication device 71. 【0080】 Information regarding the rice transplanter 10 includes the transplanter's location (latitude, longitude), time, and travel information for each location (travel direction, travel speed, etc.). Information regarding the multicopter 50 includes the multicopter's flight location (latitude, longitude, altitude), time, and flight information for each location (flight direction, flight speed, etc.). Therefore, the multicopter 50 operates according to the remote control of the server 70. 【0081】As shown in Figure 4, the multicopter 50 flies with the material S (e.g., seedling mat M) held by the holding device 51, according to the remote control of the server 70, and approaches the working machine 1 from behind while it is traveling in a straight line (e.g., while traveling along a straight line path L11), moving to a point above the receiving platform 90 (flight process to replenish seedlings: outbound process). Then, according to the remote control of the server 70, as shown in Figure 3, when the multicopter 50 reaches the point above the receiving platform 90 of the working machine 1, it releases the material S by releasing the holding device 51 and drops the material S onto the receiving platform 90 of the rice transplanter 10 (release process: drop process). Then, according to the remote control of the server 70, as shown in Figure 4, after releasing the material S, the multicopter 50 moves from the point above the receiving platform 90 to the starting point (e.g., seedling storage area) (flight process to replenish seedlings: return process). 【0082】 Here, we will explain the altitude corresponding to the flight path of the multicopter 50. Figure 8 is a side view of a work vehicle showing an example of the altitude according to the stages in the flight path of the agricultural flying device 5 (multicopter 50). The support base 90 of the rice transplanter 10 is at a ground height H1, and the positioning device 32A is at a ground height H2. As shown in Figure 8, the flight altitude of the multicopter 50 is a normal flight height H3 and a flight height H5 when dropping the seedling mat M. For example, the control device 50f performs altitude maintenance control to maintain the altitude corresponding to the flight path of the multicopter 50 (normal flight height H3 and flight height H5 when dropping the seedling mat M). 【0083】 As shown in Figure 8, the normal flight altitude H3 of the multicopter 50 is the flight altitude on the outbound journey (route to replenish seedlings) and the return journey (route to replenish seedlings) shown in Figure 4. The normal flight altitude H3 is higher than the ground height H2 of the positioning device 32A. 【0084】When the multicopter 50 is positioned at a predetermined distance behind the rice transplanter 10, it descends from the normal flight height H3 to a flight height H5 as shown in Figure 8, and then performs a pursuit flight to catch up with the rice transplanter 10. Alternatively, when the multicopter 50 is positioned at a predetermined distance behind the rice transplanter 10, it may perform a pursuit flight to catch up with the rice transplanter 10 while descending from the normal flight height H3 to a flight height H5. By pursuing the rice transplanter 10 at a speed faster than the rice transplanter 10, the multicopter 50 catches up with the rice transplanter 10 and reaches above the support platform 90 of the rice transplanter 10 (accelerated flight process). 【0085】 As shown in Figure 8, the flight height H5 when the seedling mat M is dropped is lower than the ground height H2 of the positioning device 32A. By subtracting the ground height H1 of the receiving platform 90 from the flight height H5 of the multicopter 50, it can be seen that the distance from the receiving platform 90 to the multicopter 50 directly above is the height H6 shown in Figure 8. At a height of H6, the distance from which the seedling mat M is dropped to the receiving platform 90 is short, so the seedling mat M can be safely delivered to the receiving platform 90 without being damaged by the impact of the drop. 【0086】 While the multicopter 50 is flying above the implement 1 (rice transplanter 10), it releases the material S (seedling mat M) from the holding device 51 (release step) and drops it onto the moving implement 1 (release step). In other words, the multicopter 50 replenishes the seedling mat M to the moving rice transplanter 10 while flying above the implement 1 (i.e., without landing on the rice transplanter 10). 【0087】 As shown in Figure 8, in the first state, when the multicopter 50 is flying above the support stand 90 provided on the rice transplanter 10 and within a predetermined height (height H6 shown in Figure 8) from the support stand 90, the holding device 51 releases the holding device and drops the material S (seedling mat M) onto the support stand 90 (dropping process), thereby supplying the seedling mat M to the rice transplanter 10 which is moving in a straight line. The first state is the state in which the multicopter 50 is positioned within a predetermined height (height H6 shown in Figure 8) from the support stand 90. In other words, the first state is the state in which the multicopter 50 is positioned within a height from the ground (flight height H5 (H5 = H1 + H6) shown in Figure 8). 【0088】In the first state, where the multicopter 50 is positioned at a height H6 from the support stand 90 shown in Figure 8, it flies while maintaining a state in which its direction of travel and speed are aligned with the direction of travel and speed of the rice transplanter 10 (maintained flight process). In the first state, as shown in Figure 8, when the relative speed of the multicopter 50 with respect to the rice transplanter 10 is zero or within a specified range value from zero to the first relative speed (parallel flight process), the multicopter 50 supplies the seedling mat M to the rice transplanter 10 which is traveling in a straight line. 【0089】 During flight in the first state shown in Figure 8, the multicopter 50 releases the seedling mat M from the holding device 51, thereby dropping the seedling mat M onto the receiving platform 90. 【0090】 Here, the overall flow of remote control of the multicopter 50 by the server 70 will be explained in detail. The remote control device 72 transmits various remote instructions (for example, the first to fourth remote instructions) to the multicopter 50. For example, the first remote instruction is an instruction for the outward flight towards the rice transplanter 10. The second remote instruction is an instruction for a follow flight to catch up with the rice transplanter 10 from a position behind the moving rice transplanter 10. The third remote instruction is an instruction for seedling dropping (material dropping). The fourth remote instruction is an instruction for the return flight to the seedling storage area. 【0091】 The remote control device 72 transmits a first remote instruction to the multicopter 50 when the server 70 determines that it is time to start, or when the rice transplanter 10 detects that the remaining amount of seedlings in the seedling mat M has fallen below a predetermined level. Based on the first remote instruction, the multicopter 50 performs an outbound flight (see Figure 4) from its current position toward the rice transplanter 10. When the multicopter 50 arrives at the position behind the rice transplanter 10 shown in Figure 4, it transmits an arrival signal to the server 70 indicating its arrival at the position behind the rice transplanter 10. 【0092】When the communication device 71 of the server 70 receives an arrival signal, or when the remote control device 72 determines that the flight position of the multicopter 50, which is transmitted sequentially from the multicopter 50, matches the position behind the rice transplanter 10, it transmits a second remote instruction to the multicopter 50. Based on the second remote instruction, the multicopter 50 performs a follow flight to catch up with the rice transplanter 10 from its position behind the moving rice transplanter 10. A follow flight is a flight from its position behind the moving rice transplanter 10 until it catches up with the rice transplanter 10 and is positioned directly above the support stand 90. During seedling replenishment, the multicopter 50 enters a first state in which it is positioned above the support stand 90 of the rice transplanter 10 and within a predetermined height (height H6 shown in Figure 8) from the support stand 90. Then, in the seedling supply route shown in Figure 4, the multicopter 50 flies in such a way that in the first state, its relative speed with respect to the rice transplanter 10 is zero or within a specified range from zero to the first relative speed. At this time, if the multicopter 50's relative speed with respect to the rice transplanter 10 is zero or within a specified range from zero to the first relative speed in the first state, it transmits a ready signal (READY signal) to the server 70 indicating that preparations for dropping seedlings are complete. 【0093】 When the communication device 71 receives a ready signal, the remote control device 72 transmits a third remote instruction (material dropping instruction) to the multicopter 50. Based on the third remote instruction, the multicopter 50 releases the holding device 51 from holding the seedling mat M (seedlings Se) and drops the seedlings onto the receiving stand 90. Once the seedling dropping is complete, the multicopter 50 transmits a dropping completion signal to the server 70 indicating that the dropping of the seedling mat M (seedlings Se) is complete. 【0094】 When the communication device 71 of the server 70 receives a drop completion signal, the remote control device 72 transmits a fourth remote instruction to the multicopter 50. Based on the fourth remote instruction, the multicopter 50 performs a return flight (see Figure 4) from its current position back to the seedling placement site. 【0095】The display control unit 74 of the server 70 may sequentially display information regarding the multicopter 50 on the display unit 66 of the mobile terminal 61. The information regarding the multicopter 50 includes, but is not limited to, identification information of the multicopter 50 and the status of the multicopter 50. 【0096】 The identification information for the multicopter 50 is an identification code for identifying the multicopter 50, but it may also be a name or the like. The status of the multicopter 50 indicates the status of the multicopter 50 during the seedling replenishment flight, and includes, for example, seedling placement location, pre-seedling holding state, seedling holding state, in the outbound flight, reached the rear position of the rice transplanter 10, in the follow flight, ready to drop seedlings, seedlings dropped, in the return flight, and completion. This information is transmitted sequentially from the communication device 50i of the multicopter 50 to the server 70, or generated by the server 70 based on the position information and status information of the rice transplanter 10 and the multicopter 50. The status of the multicopter 50 is transmitted from the server 70 to the mobile terminal 61. Therefore, the status of the multicopter 50 is displayed on the display unit 66 of the mobile terminal 61. 【0097】 Now, the control device 50f controls the rotation speed of the rotor blades 50c when dropping the material S, in addition to altitude maintenance control according to the flight path of the multicopter 50. Here, the rotation speed control of the rotor blades 50c of the multicopter 50 when dropping the material S (seedling mat M) will be explained using Figure 9. Figure 9 is a diagram showing the rotation speed of the rotor blades 50c and the altitude of the aircraft 50a when dropping the material S (seedling mat M). 【0098】 Here, we assume that the multicopter 50 is in a first state, as shown in Figure 8, with the holding device 51 holding the material S (seedling mat M), and flying above the support base 90 of the rice transplanter 10 at a flight height H5. 【0099】 As shown in Figure 9, the rotational speed of the rotor blade 50c decreases when the holding device 51 transitions from a holding state to a release state. In other words, the holding device 51 transitions to a release state while the rotational speed of the rotor blade 50c decreases. 【0100】For example, rotation speed reduction control is performed such that the reduction in rotation speed of the rotor blade 50c begins (for example, control starts at time t2) within the period from when the release state is instructed (i.e., from the reception timing (e.g., time t1) when the holding device 51 receives the release signal instructing the release state) to the release timing (e.g., time t3) when the holding device 51 enters the release state, and ends (for example, ends at time t4) after the release timing (e.g., time t3). In other words, the rotation speed reduction control period T1 of the rotor blade 50c is the period from time t2 to time t4. 【0101】 The rotational speed of the rotor blade 50c (second rotational speed R2) when the aforementioned reduction is completed (time t4) is lower than the rotational speed of the rotor blade 50c (first rotational speed R1) before the release state is instructed (for example, before the reception timing (time t1)), and is the rotational speed at which the multicopter 50 maintains flight at flight height H5 with the material S released. Note that the first rotational speed R1 is not limited to the rotational speed of the rotor blade 50c immediately before the reception timing (time t1), but may also be the rotational speed of the rotor blade 50c at the reception timing (time t1). 【0102】 The multicopter 50 stores the rotation speed of the rotor blades 50c and the time in a memory unit 50h at predetermined intervals (every few seconds or several hundred milliseconds), so it is possible to obtain the rotation speed of the rotor blades 50c immediately before the reception timing (time t1) and the rotation speed of the rotor blades 50c at the reception timing (time t1). 【0103】 The control device 50f reduces the rotational speed of the rotor blade 50c based on the weight of the material S to be released. For example, the control device 50f defines the amount of reduction in the rotational speed of the rotor blade 50c corresponding to the weight of the material S to be released. For example, the reduction amount is defined as the first reduction amount or the second reduction amount shown in the memory table TB1 shown in Figure 14, which will be described later. When the holding device 51 transitions from the holding state to the release state, the control device 50f reduces the rotational speed of the rotor blade 50c to a target rotational speed (second rotational speed R2) which is obtained by reducing the rotational speed before the start of the reduction (first rotational speed R1) by the reduction amount (for example, the first reduction amount or the second reduction amount shown in Figure 14). 【0104】The control device 50f controls the reduction of the rotation speed of the rotor blade 50c based on the output timing of outputting a release signal to the holding device 51 to indicate the release state. 【0105】 As shown in Figure 9, at times t1 and t2, the multicopter 50 maintains a flight altitude H5. As the rotation speed of the rotor blades 50c decreases from time t2 to time t3, the multicopter 50 slightly drops to a flight altitude H51 at time t3. However, at time t3, the release (dropping) of the seedling mat M instantly eliminates the weight of the seedling mat M, and immediately afterward, the decrease in the rotation speed of the rotor blades 50c stops (i.e., the decrease stops at the rotation speed required to maintain a flight altitude H5 without holding the seedling mat M (second rotation speed R2)), and the multicopter 50 returns to flight altitude H5 and continues flying. 【0106】 At time t3, the payload (carrying weight) decreases dramatically. In other words, the total weight LC1 of the multicopter 50 flying while holding the seedling mat M is suddenly reduced to LC2, which is the weight of the multicopter 50 alone, minus the weight of the seedling mat M. 【0107】 Next, the control of the rotation speed of the rotor blades 50c of the multicopter 50 when dropping the material S (granules in container 51A) all at once will be explained using Figure 10. Figure 10 is a diagram showing the rotation speed of the rotor blades 50c and the altitude of the aircraft 50a when dropping the material S (granules). Figure 11 is a diagram showing an agricultural flying device 5 having a holding device 51 that holds the container 51A containing the granules. 【0108】 In this context, the multicopter 50 is assumed to be holding the container 51A containing the granules, as shown in Figure 11, and to be hovering above the target drop location at a flight height H5. 【0109】The container 51A has an opening / closing device 51C that can open and close an opening 51B provided at the bottom. The opening / closing device 51C has, for example, a pair of door members 51C1, and can transition between a closed state in which the opening 51B is covered by the pair of door members 51C1, and an open state in which the opening 51B is opened by opening the pair of door members 51C1 downwards. This opening 51B is large enough to allow the granular material inside the container 51A to be dropped in all at once. In other words, the opening 51B is large enough to drop a large number of granular materials simultaneously. Note that the opening 51B of the opening / closing device 51C is not limited to being opened by a pair of door members 51C1, but may also be opened by a shutter member or a bottom plate. 【0110】 The holding device 51 can, for example, output an open signal or a close signal to the switch 51C, thereby changing the switch 51C between an open state and a closed state. 【0111】 As shown in Figure 10, the rotation speed of the rotor blade 50c decreases when the holding device 51 moves the pair of door members 51C1 of the container 51A to an open state (i.e., the opening 51B from a closed state to an open state). In other words, the opening 51B of the container 51A moves from a closed state to an open state while the rotation speed of the rotor blade 50c decreases. 【0112】 For example, the reduction in the rotational speed of the rotor blade 50c begins (for example, control starts at time t2) within the period from the reception timing (for example, time t1) when the holding device 51 receives a release signal instructing the opening 51B of the container 51A to be in an open state, to the release timing (for example, time t3) when the opening 51B of the container 51A is in an open state, and the reduction in the rotational speed of the rotor blade 50c ends (for example, ends at time t4) after the release timing (for example, time t3). In other words, the control period T1 for reducing the rotational speed of the rotor blade 50c is the period from time t2 to time t4. 【0113】The rotational speed of the rotor blade 50c (second rotational speed R2) when the aforementioned decrease is completed (time t4) is lower than the rotational speed of the rotor blade 50c (first rotational speed R1) before the reception timing (time t1), and is the rotational speed at which the multicopter 50 maintains flight immediately after the granular material in container 51A is released all at once. Note that the first rotational speed R1 is not limited to the rotational speed of the rotor blade 50c immediately before the reception timing (time t1), but may also be the rotational speed of the rotor blade 50c at the reception timing (time t1). 【0114】 The multicopter 50 stores the rotation speed of the rotor blades 50c and the time in a memory unit 50h at predetermined intervals, so it is possible to obtain the rotation speed of the rotor blades 50c immediately before the reception timing (time t1) and the rotation speed of the rotor blades 50c at the reception timing (time t1). 【0115】 The control device 50f reduces the rotational speed of the rotor blades 50c based on the weight of the material S to be released. For example, the control device 50f defines the amount of reduction in the rotational speed of the rotor blades 50c corresponding to the weight of the material S to be released, and when the holding device 51 transitions from the holding state to the release state, it reduces the rotational speed of the rotor blades 50c to a target rotational speed (second rotational speed R2) which is obtained by reducing the rotational speed before the reduction started (first rotational speed R1) by the aforementioned reduction amount. 【0116】 The control device 50f controls the reduction of the rotation speed of the rotor blade 50c based on the output timing of outputting a release signal to the holding device 51 to open. 【0117】 As shown in Figure 10, at times t1 and t2, the multicopter 50 maintains a flight altitude H5. As the rotation speed of the rotor blades 50c decreases from time t2 to time t3, the multicopter 50 slightly drops to a flight altitude H51 at time t3. However, at time t3, the granules in container 51A are released all at once, instantly reducing the weight of all the granules in container 51A to zero. Immediately afterward, the decrease in the rotation speed of the rotor blades 50c stops (i.e., the decrease stops at the rotation speed (second rotation speed R2) required to maintain a flight altitude H5 with no granules left in container 51A), and the multicopter 50 returns to flight altitude H5 and continues flying. 【0118】At time t3, the payload (carrying weight) has drastically decreased. In other words, the total weight LC11 of the multicopter 50 flying while holding the container 51A containing the granules has been instantly reduced to the weight LC12 of the multicopter 50 alone, which is the weight of the multicopter 50 minus the weight of all the granules in the container 51A. 【0119】 Here, we will explain the flight control of the multicopter 50, including the dropping of material S (seedling mat M or granules in container 51A). Figure 12 is a flowchart showing an example of the control setting process according to the type of material S and the number of times it is dropped. 【0120】 As shown in Figure 12, the server 70 obtains the weight and number of times the material S is dropped (S11). For example, the server 70 obtains the weight and number of times the material S is dropped based on the configuration information transmitted from the mobile terminal 61. 【0121】 Figure 15 shows an example of a settings screen G1 displayed on a mobile terminal 61. The mobile terminal 61 displays the settings screen G1 shown in Figure 15 based on a predetermined touch operation to display the settings screen G1. The settings screen G1 shown in Figure 15 includes an input field 66a for setting the type of material S, an input field 66b for setting the type of material S, an input field 66c for setting the weight of material S, and an input field 66d for setting the number of times material S is dropped. By touching the pull-down buttons at the right end of each input field 66a to 66d, multiple selectable items are displayed, and the setting can be made by selecting any item from among the multiple items. In addition, information such as numerical values ​​may be directly entered into each input field 66a to 66d by touch operation. 【0122】 First, let's explain the case where seedling mat M is set as the type of material S. In Figure 15, seedling mat M is set as the type of material S in input field 66a, and the type of seedling mat M is set to TY-A1 in input field 66b. When the type is set to TY-A1, the weight of this type of seedling mat M is automatically set to the first weight (kg) in input field 66c. The weight (kg) of the seedling mat M may also be entered in input field 66c. The number of times material S is dropped is set to 1 in input field 66d. 【0123】 Next, we will explain the case where the type of material S is granular material placed in container 51A, using Figure 16. 【0124】 Figure 16 shows an example of the settings screen G1 displayed on the mobile terminal 61. In Figure 16, input field 66a is set to granular material as the type of material S, and input field 66b is set to TY-B1 as the type of container 51A containing the granular material S. When the type is set to TY-B1, input field 66c is automatically set to the second weight (kg) of the granular material in container 51A of this type. The weight (kg) of the granular material in container 51A may also be entered in input field 66c. Input field 66d is set to 1 as the number of times material S is dispensed. 【0125】 The mobile terminal 61 transmits the setting information configured on the setting screen G1 shown in Figure 15 or Figure 16 to the server 70. 【0126】 Server 70 obtains the weight and number of times the material S is dropped (S11). Based on the acquired configuration information, Server 70 determines whether the type of material S is granular (S12). For example, if the type of material S included in the configuration information from the mobile terminal 61 is seedling mat M, Server 70 determines that it is not granular (No in S12). On the other hand, if the type of material S included in the configuration information from the mobile terminal 61 is granular, Server 70 determines that it is granular (Yes in S12). 【0127】 Figure 14 shows an example of a storage table TB1 that shows the relationship between the type of material S, the weight of the material, and the decrease in rotational speed. The storage unit 73 of the server 70 is equipped with the storage table TB1 shown in Figure 14. As shown in Figure 14, the storage table TB1 stores the type of material S, the weight of the material, and the decrease in the rotational speed of the rotor blade 50c in association with each other. For example, if the type of material S is seedling mat M and its weight is the first weight, the decrease in the rotational speed of the rotor blade 50c becomes the first decrease. Also, if the type of material S is granular material and the weight of the granular material in container 51A is the second weight, the decrease in the rotational speed of the rotor blade 50c becomes the second decrease. 【0128】If the type of material S is not granular (No in S12), that is, if the type of material S is seedling mat M, the server 70 sets the first control setting and transmits the first control setting to the multicopter 50 (S13). The first control setting includes that the type of material S is seedling mat M, the type of seedling mat M is TY-A1, the weight of the seedling mat M is the first weight (kg), the number of times the material S is dropped is 1, and the amount of decrease in the rotation speed of the rotor blade 50c when the seedling mat M is dropped is the first decrease amount. When the multicopter 50 is flying at a flight height H5 while holding the seedling mat M, the change to a state where it is not holding the seedling mat M causes the multicopter 50 to rise to a position higher than the flight height H5. For this reason, the first decrease amount is the amount of decrease in rotation speed required to return from that higher position to the original flight height H5. 【0129】 Furthermore, in S13, the server 70 only needs to transmit at least the first reduction amount of the first control setting to the multicopter 50. 【0130】 The control device 50f of the multicopter 50 stores the received first control setting in the memory unit 50h, and uses the first control setting to control the reduction of the rotation speed of the rotor blades 50c when dropping the seedling mat M. 【0131】 On the other hand, if the type of material S is granular (Yes in S12), the server 70 sets the second control setting and transmits the second control setting to the multicopter 50 (S14). The second control setting includes that the type of material S is granular, the type of container 51A containing the granular material is TY-A1, the weight of the granular material in this type of container 51A is the second weight (kg), the number of times the material S is dropped is 1, and the amount of decrease in the rotation speed of the rotor blades 50c when the granular material is dropped is the second decrease amount. When the multicopter 50 is flying at a flight height H5 while holding the container 51A containing the granular material, the state changes to one where the granular material in the container 51A has been dropped (not held), causing the multicopter 50 to rise to a position higher than the flight height H5. For this reason, the second decrease amount is the amount of decrease in rotation speed required to return from that higher position to the original flight height H5. 【0132】Furthermore, in S14, the server 70 only needs to transmit at least the second reduction amount of the second control setting to the multicopter 50. 【0133】 The control device 50f of the multicopter 50 stores the received second control setting in the memory unit 50h, and uses the second control setting to control the reduction of the rotation speed of the rotor blades 50c when dropping the granules in the container 51A all at once. 【0134】 In this case, the sudden discharge involves releasing a large amount of granular material from container 51A all at once, resulting in a steep decrease in the loaded weight (for example, a significant portion, such as all or half of the loaded weight, suddenly drops to zero). In contrast, in the case of so-called pesticide spraying, the loaded weight of the pesticide decreases gradually over the duration of the work in the field, resulting in a very gradual decrease in the loaded weight. For this reason, when the granular material from container 51A is discharged all at once, the rotation speed of the rotor blade 50c is controlled to decrease. 【0135】 Figure 17 is a flowchart showing an example of the rotation speed reduction control process for the rotor blade 50c. As shown in Figure 17, the control device 50f of the multicopter 50 determines whether or not there is a third remote instruction (instruction to drop seedlings) from the server 70 (S21). If the control device 50f has not received the third remote instruction (instruction to drop seedlings) (No in S21), it returns to S21 and waits until it receives the third remote instruction. 【0136】 When the control device 50f receives the third remote instruction (instruction to drop seedlings) (Yes in S21), it outputs a release signal to the holding device 51 to indicate the release state, that is, the holding device 51 receives the release signal indicating the release state (S22). The output timing at which the control device 50f outputs the release signal to the holding device 51 is approximately the same as the reception timing at which the holding device 51 receives the release signal, but there is a minute delay in the millisecond range. For example, suppose the reception timing was time t1 as shown in Figure 9. 【0137】 As shown in Figure 17, the control device 50f starts controlling the reduction of the rotational speed of the rotor blade 50c (S23). The reduction in the rotational speed of the rotor blade 50c starts at time t2, which is a small time after time t1, as shown in Figure 9. 【0138】As shown in Figure 17, the holding device 51 enters a released state based on the release signal (S24). For example, the release timing is time t3 as shown in Figure 9. At time t3, the seedling mat M is released (dropped) from the holding device 51, so the weight of the seedling mat M becomes zero all at once. In other words, the total load weight becomes zero all at once. 【0139】 As shown in Figure 17, the control device 50f stops reducing the rotational speed of the rotor blade 50c a small time after the release timing (for example, time t3) (S24). As shown in Figure 9, the reduction in the rotational speed of the rotor blade 50c ends at time t4. 【0140】 <First Modification> In the above embodiment, the server 70 defines the amount of reduction in the rotational speed of the rotor blade 50c as a first reduction amount when the material S is a seedling mat M, and as a second reduction amount when the material S is granular material (or liquid material) in a container 51A, using the storage table TB1 shown in Figure 14, and transmits the first control setting (S13) and the second control setting (S14) to the multicopter 50 as shown in Figure 15, but is not limited to this. 【0141】 For example, the server 70 may define a reduction amount as shown in Figure 13 and send a control setting including this defined reduction amount to the multicopter 50. Figure 13 is a flowchart showing another example of the control setting process. 【0142】 As shown in Figure 13, the server 70 flies the multicopter 50 at a flight height H5 without holding the seedling mat M, and transmits the rotation speed of the rotor blades 50c at this time to the server 70 to obtain it as the second rotation speed R2 (S31). 【0143】 The server 70 flies the multicopter 50 at a flight height H5 while holding the seedling mat M, and transmits the rotation speed of the rotor blades 50c at this time to the server 70 to obtain it as the first rotation speed R1 (S32). 【0144】The server 70 stores the value obtained by subtracting the second rotation speed R2 from the first rotation speed R1 as the first reduction amount (S33). The server 70 generates a first control setting including the first reduction amount and transmits it to the multicopter 50 (S34). In this way, the server 70 measures (acquires) the first rotation speed R1 and the second rotation speed R2 in advance and uses the value obtained by subtracting the second rotation speed R2 from the first rotation speed R1 as the first reduction amount, so that the reduction amount can be made to match the actual conditions in the field. 【0145】 <Second Modification> The holding device 51 in the above-described embodiment is designed to hold one seedling mat M. In contrast, the holding device 51 in the second modification may be capable of holding multiple (for example, two) seedling mats M and may be capable of dropping seedling mats M individually. 【0146】 Figure 18 shows the rotation speed of the rotor blade 50c and the altitude of the aircraft 50a when material S (seedling mat M) is dropped multiple times. 【0147】 Here, we assume that the multicopter 50 is in a first state, as shown in Figure 18, with the holding device 51 holding two materials S (seedling mats M), and flying above the support base 90 of the rice transplanter 10 at a flight height H5. 【0148】 As shown in Figure 18, the rotational speed of the rotor blade 50c decreases when the holding device 51 transitions from a holding state to a release state. In other words, the holding device 51 transitions to a release state while the rotational speed of the rotor blade 50c decreases. 【0149】 For example, the reduction in the rotational speed of the rotor blade 50c begins (for example, control starts at time t2) within the period from the reception timing (for example, time t1) when the holding device 51 receives a first release signal indicating a release state to the release timing (for example, time t3) when the first holding device 51 enters a release state, and the reduction in the rotational speed of the rotor blade 50c ends (for example, at time t4) after the release timing (for example, time t3). In other words, the control period T1 for reducing the rotational speed of the rotor blade 50c is the period from time t2 to time t4. 【0150】The rotational speed of the rotor blade 50c (second rotational speed R2) at the time the aforementioned decrease ends (time t4) is lower than the rotational speed of the rotor blade 50c before the reception timing (time t1) (first rotational speed R1), and is the rotational speed at which the multicopter 50 maintains flight when the first material S is released. Note that the first rotational speed R1 is not limited to the rotational speed of the rotor blade 50c immediately before the reception timing (time t1), but may also be the rotational speed of the rotor blade 50c at the reception timing (time t1). 【0151】 The multicopter 50 stores the rotation speed of the rotor blades 50c and the time in a memory unit 50h at predetermined intervals, so it is possible to obtain the rotation speed of the rotor blades 50c immediately before the reception timing (time t1) and the rotation speed of the rotor blades 50c at the reception timing (time t1). 【0152】 The control device 50f reduces the rotational speed of the rotor blades 50c based on the weights of the first and second materials S that are released. For example, the control device 50f defines the amount of reduction in the rotational speed of the rotor blades 50c corresponding to the weight of the first material S that is released, and when the first holding device 51 transitions from the holding state to the release state, it reduces the rotational speed of the rotor blades 50c to a target rotational speed (second rotational speed R2) which is obtained by reducing the rotational speed before the reduction started (first rotational speed R1) by the aforementioned reduction amount. 【0153】 The control device 50f defines the amount of reduction in the rotational speed of the rotor blade 50c corresponding to the weight of the second material S to be released, and when the second holding device 51 transitions from the holding state to the release state, it reduces the rotational speed of the rotor blade 50c to a target rotational speed (third rotational speed R3) which is obtained by reducing the rotational speed before the reduction started (second rotational speed R2) by the aforementioned reduction amount. 【0154】As shown in Figure 18, at times t1 and t2, the multicopter 50 maintains a flight altitude H5. As the rotation speed of the rotor blades 50c decreases from time t2 to t3, the multicopter 50 slightly drops to a flight altitude H51 at time t3. However, at time t3, the multicopter 50 returns to flight altitude H5 because the weight of the first seedling mat M is instantly reduced to zero upon release (dropping) of the first seedling mat M, and immediately afterward, the decrease in the rotation speed of the rotor blades 50c stops (i.e., the decrease stops at the rotation speed (second rotation speed R2) required to maintain a flight altitude H5 without holding the first seedling mat M). 【0155】 Furthermore, as shown in Figure 18, at times t11 and t12, the multicopter 50 maintains a flight altitude H5. As the rotation speed of the rotor blades 50c decreases from time t12 to time t13, the multicopter 50 slightly drops to a flight altitude H51 at time t13. However, at time t13, the release (dropping) of the second seedling mat M instantly eliminates the weight of the second seedling mat M, and immediately afterward, the decrease in the rotation speed of the rotor blades 50c stops (that is, the decrease stops at the rotation speed (third rotation speed R3) required to maintain a flight altitude H5 without holding two seedling mats M), and the multicopter 50 returns to flight altitude H5 and continues flying. 【0156】 The main characteristic features and effects of the agricultural flying device 5 in the embodiments described above are as follows: 【0157】 (Item A1) An agricultural flying device 5 comprising an aircraft body 50a, a rotor blade 50c provided on the aircraft body 50a, and a holding device 51 provided on the aircraft body 50a that can be changed between a holding state for holding materials S and a release state for releasing materials S, wherein the rotation speed of the rotor blade 50c decreases when the holding device 51 transitions from the holding state to the release state. 【0158】With this configuration, when the holding device 51 transitions from the holding state to the release state, the rotation speed of the rotor blade 50c decreases, which suppresses the upward movement of the aircraft 50a caused by the rapid decrease in payload weight due to the release of the materials S. Therefore, the agricultural flying device 5 can maintain stable flight even when the payload weight decreases rapidly. 【0159】 (Item A2) The agricultural flying device 5 according to Item A1, wherein the holding device 51 transitions to the released state while the rotational speed of the rotor blade 50c decreases. 【0160】 With this configuration, as the rotation speed of the rotor blade 50c decreases, the holding device 51 transitions to a released state, which effectively suppresses the upward movement of the aircraft body 50a due to a rapid decrease in the load weight. 【0161】 (Item A3) The agricultural flying device 5 according to Item A1 or A2, wherein the decrease in the rotational speed of the rotor blade 50c begins within the period from the instruction to release the release state until the release timing when the holding device 51 enters the release state, and the decrease in the rotational speed of the rotor blade 50c ends after the release timing. 【0162】 With this configuration, the decrease in the rotational speed of the rotor blade 50c begins within the period from the timing of the holding device 51 receiving and outputting the release signal to the release state of the holding device 51 (release timing), and ends immediately after the release timing. Therefore, the rotational speed of the rotor blade 50c is decreasing at the release timing, and the decrease in rotational speed of the rotor blade 50c is timed to coincide with the release timing when the load weight drops sharply. Thus, the decrease in the rotational speed of the rotor blade 50c can be timed appropriately. 【0163】 (Item A4) The agricultural flying device 5 described in Item A3, wherein the rotational speed of the rotor blade 50c when the reduction is completed is lower than the rotational speed of the rotor blade 50c before the release state is instructed, and is a rotational speed that maintains flight when the material S is released. 【0164】 With this configuration, flight can continue after the release of resource S, just as it did before the release of resource S. 【0165】(Item A5) An agricultural flying device 5 according to any one of items A1 to A4, comprising a control device 50f that reduces the rotational speed of the rotor blade 50c based on the weight of the material S to be released. 【0166】 With this configuration, the rotation speed of the rotor blade 50c can be reduced by the amount by which the load weight decreases due to the release of the material S, and the upward movement of the aircraft body 50a due to the release of the material S can be appropriately suppressed. 【0167】 (Item A6) The agricultural flying device 5 as described in Item A5, wherein the control device 50f defines a reduction in the rotational speed of the rotor blade 50c corresponding to the weight of the material S to be released, and when the holding device 51 transitions from the holding state to the release state, it reduces the rotational speed of the rotor blade 50c to a target rotational speed obtained by reducing the rotational speed before the start of the reduction by the reduction amount. 【0168】 With this configuration, when the load weight decreases due to the release of materials S, the target rotation speed of the rotor blade 50c can be easily and quickly changed, and reduction control can be appropriately performed. 【0169】 (Item A7) The agricultural flying device 5 described in Item A5, wherein the control device 50f controls the reduction of the rotation speed of the rotor blade 50c based on the output timing of outputting a release signal to the holding device 51 to indicate the release state. 【0170】 With this configuration, the control device 50f controls the reduction of the rotation speed of the rotor blade 50c based on the output timing of the release signal output to the holding device 51, so that the reduction control can be performed at an appropriate time. 【0171】 (Item A8) The holding device 51 is located at the lower part of the aircraft body 50a, and is an agricultural flying device 5 as described in any one of items A1 to A7. 【0172】 With this configuration, the agricultural flying device 5, which drops materials S by releasing the holding device 51 at the bottom of the aircraft body 50a, can maintain stable flight even when the payload weight drops sharply. 【0173】(Item A9) The material S is a seedling mat M, which is the agricultural flying device 5 described in any one of Items A1 to A8. 【0174】 With this configuration, in an agricultural flying device 5 that drops seedling mats M, stable flight can be maintained even when the load weight (weight of seedling mats M) suddenly becomes zero the moment the holding of the seedling mats M is released. 【0175】 (Item A10) The material S is granular, liquid, or seeds placed in a container 51A, and the holding device 51 drops the material S from the container 51A by opening the opening 51B of the container 51A, as described in any one of items A1 to A9. 【0176】 According to this configuration, in an agricultural flying device 5 of the type in which granules, liquids, or seeds in a container 51A are dropped by opening the opening 51B of the container 51A held by the holding device 51, the granules or liquids in the container 51A are dropped all at once in a short time from the moment the opening 51B of the container 51A is opened. In other words, stable flight can be maintained even when the load weight (the weight of the granules or liquids in the container 51A) drops sharply to zero. 【0177】 Furthermore, the rotation speed reduction control of the rotor blade 50c in the above embodiments and modified examples may be performed during either mobile flight (such as when flying alongside a moving work machine 1) or hovering flight (stationary flight) of the agricultural flying device 5 (multicopter 50). 【0178】 In the embodiments and modifications described above, the multicopter 50 follows the rice transplanter 10 which is traveling in automatic mode, catches up to the rice transplanter 10, and replenishes (transports) the materials S. However, it may also follow the rice transplanter 10 which is traveling in remote or manual mode, catch up to the rice transplanter 10, and replenish (transports) the materials S. 【0179】 In the embodiments and modifications described above, the multicopter 50 is flown by remote control from the server 70, but it may also be flown by remote control from the rice transplanter 10 or the portable terminal 61. The rice transplanter 10 or the portable terminal 61 only needs to include the remote control device 72 and the storage unit 73, which are components of the server 70. 【0180】 Furthermore, in the embodiments and modifications described above, the multicopter 50 is flown by remote control from the server 70, but it may also fly autonomously. When the multicopter 50 flies autonomously, the server 70 may be equipped with a remote control device 72 and a storage unit 73, and the control device 50f of the multicopter 50 may make decisions corresponding to the first to fourth remote instructions from the remote control device 72 of the server 70. 【0181】 Having described the present invention above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended to be included. 【0182】 1. Work machine 5. Agricultural flying device 50a. Aircraft 50c. Rotary wing 51. Holding device 57. Control device M. Seedling mat S. Materials

Claims

1. An agricultural flying device comprising: an aircraft body; rotor blades provided on the aircraft body; and a holding device provided on the aircraft body that can be switched between a holding state for holding materials and a release state for releasing materials, wherein the rotational speed of the rotor blades decreases when the holding device transitions from the holding state to the release state.

2. The agricultural flying device according to claim 1, wherein the holding device transitions to the released state while the rotational speed of the rotor blade decreases.

3. The agricultural flying device according to claim 2, wherein the decrease in the rotational speed of the rotor blades begins within the period from the instruction to release the holding device to release the device, and the decrease in the rotational speed of the rotor blades ends after the release timing.

4. The agricultural flying device according to claim 3, wherein the rotational speed of the rotor blades when the reduction is completed is lower than the rotational speed of the rotor blades before the release state was indicated, and is a rotational speed that maintains flight in the state with the material released.

5. The agricultural flying device according to any one of claims 1 to 4, comprising a control device that reduces the rotational speed of the rotor blades based on the weight of the released material.

6. The agricultural flying device according to claim 5, wherein the control device defines a reduction in the rotational speed of the rotor corresponding to the weight of the material to be released, and when the holding device transitions from the holding state to the release state, it reduces the rotational speed of the rotor to a target rotational speed obtained by reducing the rotational speed before the start of the reduction by the reduction amount.

7. The agricultural flying device according to claim 5, wherein the control device controls the reduction of the rotation speed of the rotor blades based on the output timing of outputting a release signal to the holding device to indicate the release state.

8. The agricultural flying device according to any one of claims 1 to 4, wherein the holding device is located at the bottom of the aircraft.

9. The agricultural flying device according to any one of claims 1 to 4, wherein the material is a seedling mat.

10. The agricultural flying device according to any one of claims 1 to 4, wherein the material is granular, liquid, or seeds in a container, and the holding device releases the material in the container by opening the opening of the container.

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