JPWO2019208608A1 - Failure detection system, method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for detecting a failure in an agricultural machine for spraying chemicals, which is provided in the agricultural machine for spraying chemicals, for safe use by detecting the failure in advance. The pressure sensor is provided in the path from the medicine tank for storing the medicine to the medicine discharge port, and failure detection means for detecting a failure of the agricultural machine. And the failure is detected based on the acquired change in the discharge pressure of the medicine with time. [Selection diagram] Fig. 6

Description

The present invention relates to an unmanned aerial vehicle (drone) for spraying chemicals such as pesticides on a field, particularly to a drone with improved safety, a control method thereof, and a program.

The application of small unmanned helicopters (multicopters) generally called drones is progressing. One of the important fields of application thereof is spraying chemicals such as pesticides and liquid fertilizers on farmland (field) (for example, Patent Document 1). In Japan, where farmland is smaller than in Europe and the United States, it is often appropriate to use drones instead of manned airplanes and helicopters.

With technologies such as the Quasi-Zenith Satellite System and RTK-GPS (Real Time Kinematic-Global Positioning System), it became possible for a drone to accurately know its absolute position in centimeters during flight. Even in a farmland with a narrow and complicated terrain typical of the above, it is possible to autonomously fly with minimal manual operation and to efficiently and accurately apply a drug.

On the other hand, there were cases in which it was hard to say that safety considerations were sufficient for autonomous flight drones for agricultural drug spraying. A drone loaded with medicines weighs several tens of kilograms, which could have serious consequences in the event of an accident such as falling onto a person. In addition, the drone operator is usually not an expert, so a fool-proof mechanism is necessary, but the consideration for this was insufficient. Until now, there have been drone safety technologies premised on human control (for example, Patent Document 2), but in particular, addressing the safety issues peculiar to autonomous flight drones for drug spraying for agriculture There was no technology to do this.

Japanese Patent Laid-Open No. 2001-120151 Patent publication gazette JP, 2017-163265, A Patent publication gazette JP-A-11-94 Patent publication gazette JP-A-11-9847

The purpose is to detect a failure in an agricultural machine that sprays chemicals so that it can be used safely.

In order to achieve the above object, a failure detection system according to one aspect of the present invention is a system for detecting a failure, which is provided in an agricultural machine that sprays a medicine, and the medicine is stored in a medicine tank for storing the medicine. A pressure sensor provided in a path leading to the discharge port of the agricultural machine, and failure detection means for detecting a failure of the agricultural machine, wherein the failure detection means detects the discharge pressure of the medicine over time with the pressure sensor. The change is acquired, and the failure is detected based on the acquired change over time of the ejection pressure of the medicine.

Further, the agricultural machine is provided with a shutoff mechanism that shuts off a path from the medicine tank to the discharge port, and the failure detection means causes the shutoff mechanism to cut a path from the medicine tank to the discharge port. In the shut-off state, the pressure sensor may acquire a change over time in the discharge pressure of the drug, and the failure may be detected based on the acquired change over time in the discharge pressure of the drug.

Further, the shutoff mechanism may be a check valve.

Further, the shutoff mechanism may be a solenoid valve.

Further, the failure detection means may detect the failure based on a temporal change in the ejection pressure of the medicine by the pressure sensor and a temporal change in the ejection pressure of the medicine in a normal state.

Further, a plurality of the pressure sensors may be provided, and the failure detection means may detect the failure based on a temporal change in pressure loss calculated from the discharge pressure acquired by the plurality of pressure sensors. ..

Further, the agricultural machine is provided with a pump that discharges the medicine stored in the medicine tank to the downstream, and the rotation speed of a rotor that sucks the medicine from the medicine tank and discharges the medicine to the downstream in the pump. Further comprising a pump sensor for measuring, wherein the failure detection means has a ratio of the number of revolutions of the rotor of the pump measured by the pump sensor and the discharge pressure of the drug measured by the pressure sensor over time. The failure may be detected based on the change.

Further, when a failure is detected by the failure detecting means, the agricultural machine may further include control means for causing the agricultural machine to take a predetermined safe action.

The predetermined safety action is a control for retracting the agricultural machine during chemical spraying of the agricultural machine, and regulation of chemical spraying by the agricultural machine in a preparatory step before spraying chemicals on the agricultural machine. Alternatively, it may be a control for restricting the use of the agricultural machine.

Further, the agricultural machine may be a drone.

A failure detection method according to another aspect of the present invention is a method which is provided in an agricultural machine that sprays a medicine and is executed by a system for detecting a failure, wherein the system stores the medicine. A time-dependent change in the discharge pressure of the drug is acquired by a pressure sensor provided in a path from the tank to the discharge port of the drug, and the agricultural machine malfunctions based on the change in the discharge pressure of the acquired drug over time. To detect.

Further, a computer program according to still another aspect of the present invention is a computer program which is provided in an agricultural machine for spraying a medicine and is executed by a system for detecting a failure, wherein the medicine is supplied to the system. The change over time of the discharge pressure of the drug is acquired by a pressure sensor provided in the path from the stored drug tank to the discharge port of the drug, and based on the change over time of the acquired discharge pressure of the drug, Detect machine failure.

According to the present invention, it is possible to detect a failure in advance and safely use it in an agricultural machine that sprays a medicine.

It is a top view of the Example of the drug spraying drone which mounts the failure detection system which concerns on this invention. 1 is a front view of an embodiment of a drug spraying drone equipped with a failure detection system according to the present invention. It is a right side view of the Example of the drug spraying drone which mounts the failure detection system which concerns on this invention. 1 is an example of an overall conceptual diagram of a drug spraying system using an embodiment of a drug spraying drone equipped with a failure detection system according to the present invention. It is a schematic diagram showing the control function of the Example of the chemical spraying drone which mounts the failure detection system which concerns on this invention. It is a schematic diagram showing the structure of the failure detection system which concerns on this invention. It is a functional block diagram showing a part of function with which the failure detection system concerning the present invention is provided. It is a processing flow figure showing an example of processing performed by the failure detection system concerning the present invention. It is a processing flow figure showing an example of processing performed by the failure detection system concerning the present invention. It is a processing flow figure showing an example of processing performed by the failure detection system concerning the present invention.

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. The figures are all examples.

FIG. 1 is a plan view of an embodiment of a drone 100 according to the present invention, FIG. 2 is a front view (viewed from the traveling direction side), and FIG. 3 is a right side view thereof. In the specification of the present application, the drone means any power means (electric power, prime mover, etc.), control method (whether wireless or wired, and whether it is an autonomous flight type or a manual control type). Instead, it refers to all flying bodies having multiple rotors or flight means.

Rotators 101-1a, 101-1b, 101-2a, 101-2b, 101-3a, 101-3b, 101-4a, 101-4b (also called rotors) are means for flying the drone 100. Considering the balance of flight stability, airframe size, and battery consumption, it is desirable to have 8 aircraft (4 sets of 2-stage rotary blades).

The motors 102-1a, 102-1b, 102-2a, 102-2b, 102-3a, 102-3b, 102-4a, 102-4b are rotor blades 101-1a, 101-1b, 101-2a, 101-. 2b, 101-3a, 101-3b, 101-4a, 101-4b is a means for rotating (typically an electric motor, but may be a motor, etc.), one for each rotor It is desirable that the The upper and lower rotor blades (eg 101-1a and 101-1b) and their corresponding motors (eg 102-1a and 102-1b) in one set are for drone flight stability etc. It is desirable that the axes be collinear and rotate in opposite directions. Although some rotor blades 101-3b and the motor 102-3b are not shown, their positions are self-explanatory, and if there is a left side view, they are at the positions shown. As shown in FIG. 2 and FIG. 3, it is desirable that the radial member for supporting the propeller guard provided so that the rotor does not interfere with foreign matter has a structure in which the propeller guard is not horizontal but is in the shape of a tower. This is to prevent the member from buckling and deforming toward the rotor at the time of a collision and to prevent the member from interfering with the rotor.

The medicine nozzles 103-1, 103-2, 103-3, 103-4 are means for spraying medicine downward, and are preferably provided in four units. In the specification of the present application, the term “medicine” generally refers to pesticides, herbicides, liquid fertilizers, insecticides, seeds, and liquids or powders applied to fields such as water.

The drug tank 104 is a tank for storing the drug to be sprayed, and is preferably provided at a position close to the center of gravity of the drone 100 and a position lower than the center of gravity from the viewpoint of weight balance. The drug hoses 105-1, 105-2, 105-3, 105-4 are means for connecting the drug tank 104 and each drug nozzle 103-1, 103-2, 103-3, 103-4, and are rigid. It may be made of the above-mentioned material and also have a role of supporting the medicine nozzle. The pump 106 is a means for discharging the medicine from the nozzle.

FIG. 4 shows an overall conceptual diagram of a system using an example of a drug spraying application of the drone 100 according to the present invention. This figure is a schematic diagram and the scale is not accurate. The pilot 401 is a means for transmitting a command to the drone 100 by the operation of the user 402 and displaying information received from the drone 100 (for example, position, drug amount, battery level, camera image, etc.). Yes, and may be realized by a portable information device such as a general tablet terminal that runs a computer program. Although it is desirable that the drone 100 according to the present invention be controlled to perform autonomous flight, it is desirable to be able to perform manual operation during basic operations such as takeoff and return, and in an emergency. In addition to the portable information device, you may use an emergency operating device (not shown) that has a function dedicated to emergency stop (a large emergency stop button, etc. so that the emergency operating device can respond quickly in an emergency). It is desirable that it is a dedicated device equipped with). It is desirable that the pilot 401 and the drone 100 perform wireless communication by Wi-Fi or the like.

The field 403 is a rice field, a field, or the like to which the drug is sprayed by the drone 100. Actually, the topography of the farm field 403 is complicated, and there are cases where the topographic map cannot be obtained in advance or the topographic map and the situation at the site are inconsistent. Normally, the farm field 403 is adjacent to a house, a hospital, a school, another crop farm field, a road, a railroad, and the like. In addition, there may be obstacles such as buildings and electric wires in the field 403.

The base station 404 is a device that provides a master device function of Wi-Fi communication and the like, and it is desirable that the base station 404 also functions as an RTK-GPS base station and can provide an accurate position of the drone 100 (Wi-Fi Communication master unit function and RTK-GPS base station may be independent devices). The farm cloud 405 is typically a group of computers operated on a cloud service and related software, and is preferably wirelessly connected to the controller 401 by a mobile phone line or the like. The farming cloud 405 may analyze the image of the field 403 captured by the drone 100, grasp the growing condition of the crop, and perform a process for determining a flight route. Further, the drone 100 may be provided with the stored topographical information of the field 403 and the like. In addition, the history of the drone 100 flight and captured images may be accumulated and various analysis processes may be performed.

Usually, the drone 100 takes off from a landing point 406 outside the field 403 and returns to the landing point 406 after spraying a drug on the field 403 or when it becomes necessary to replenish the drug or charge the battery. The flight route (intrusion route) from the landing point 406 to the target field 403 may be stored in advance in the farm cloud 405 or the like, or may be input by the user 402 before the start of takeoff.

FIG. 5 is a schematic diagram showing the control function of the embodiment of the drug spraying drone according to the present invention. The flight controller 501 is a component that controls the entire drone, and specifically may be an embedded computer including a CPU, memory, related software, and the like. The flight controller 501, based on the input information received from the controller 401 and the input information obtained from various sensors described later, via the control means such as ESC (Electronic Speed Control), the motor 102-1a, 102-1b , 102-2a, 102-2b, 102-3a, 102-3b, 104-a, 104-b are controlled to control the flight of the drone 100. The actual rotation speed of the motors 102-1a, 102-1b, 102-2a, 102-2b, 102-3a, 102-3b, 104-a, 104-b is fed back to the flight controller 501 to perform normal rotation. It is desirable to have a configuration that can monitor whether or not it is. Alternatively, the rotary blade 101 may be provided with an optical sensor or the like so that the rotation of the rotary blade 101 is fed back to the flight controller 501.

The software used by the flight controller 501 is preferably rewritable through a storage medium or the like for function expansion/change, problem correction, or the like, or through communication means such as Wi-Fi communication or USB. In this case, it is desirable to protect by encryption, checksum, electronic signature, virus check software, etc. so that rewriting by unauthorized software is not performed. In addition, a part of the calculation process used by the flight controller 501 for control may be executed by another computer existing on the controller 401, the farm cloud 405, or another place. Since the flight controller 501 is highly important, some or all of its constituent elements may be duplicated.

The battery 502 is a means of supplying power to the flight controller 501 and other components of the drone and is preferably rechargeable. The battery 502 is preferably connected to the flight controller 501 via a power supply unit including a fuse or a circuit breaker. The battery 502 is preferably a smart battery that has a function of transmitting its internal state (amount of stored electricity, accumulated usage time, etc.) to the flight controller 501 in addition to a power supply function.

The flight controller 501 communicates with the controller 401 via the Wi-Fi slave unit function 503 and further via the base station 404, receives a necessary command from the controller 401, and transmits necessary information to the controller. It is desirable to be able to send to 401. In this case, it is desirable to encrypt the communication so as to prevent illegal acts such as interception, spoofing, and hijacking of equipment. The base station 404 preferably has an RTK-GPS base station function in addition to a Wi-Fi communication function. By combining the signal from the RTK base station and the signal from the GPS positioning satellite, the GPS module 504 can measure the absolute position of the drone 100 with an accuracy of about several centimeters. Since the GPS module 504 is highly important, it is desirable to duplicate and multiplex it. Also, in order to cope with the failure of a specific GPS satellite, each redundant GPS module 504 should use another satellite. It is desirable to control.

The acceleration sensor 505 is a means for measuring the acceleration of the drone body (further, a means for calculating the speed by integrating the acceleration), and is preferably a 6-axis sensor. The geomagnetic sensor 506 is a means for measuring the direction of the drone body by measuring the geomagnetism. The atmospheric pressure sensor 507 is a means for measuring atmospheric pressure, and can indirectly measure the altitude of the drone. The laser sensor 508 is a means for measuring the distance between the drone body and the ground surface by utilizing the reflection of laser light, and it is preferable to use an IR (infrared) laser. The sonar 509 is a means for measuring the distance between the drone body and the ground surface by utilizing the reflection of sound waves such as ultrasonic waves. These sensors may be selected depending on the drone's cost goals and performance requirements. Further, a gyro sensor (angular velocity sensor) for measuring the tilt of the machine body, a wind force sensor for measuring wind force, and the like may be added. Moreover, it is desirable that these sensors be duplicated or multiplexed. If there are multiple sensors for the same purpose, the flight controller 501 may use only one of them, and if it fails, switch to an alternative sensor. Alternatively, a plurality of sensors may be used simultaneously, and if the measurement results do not match, it may be considered that a failure has occurred.

The flow rate sensor 510 is a means for measuring the flow rate of the medicine, and is preferably provided at a plurality of places on the path from the medicine tank 104 to the medicine nozzle 103. The liquid shortage sensor 511 is a sensor that detects that the amount of the medicine has become equal to or less than a predetermined amount. The multi-spectral camera 512 is a means for photographing the field 403 and acquiring data for image analysis. The obstacle detection camera 513 is a camera for detecting a drone obstacle. Since the image characteristics and the orientation of the lens are different from those of the multispectral camera 512, it is desirable that the obstacle detection camera 513 be a device different from the multispectral camera 512. The switch 514 is a means for the user 402 of the drone 100 to make various settings. The obstacle contact sensor 515 is a sensor for detecting that the drone 100, in particular, its rotor or propeller guard portion has come into contact with an obstacle such as an electric wire, a building, a human body, a tree, a bird, or another drone. .. The cover sensor 516 is a sensor that detects that the operation panel of the drone 100 and the cover for internal maintenance are open. The drug injection port sensor 517 is a sensor that detects that the injection port of the drug tank 104 is open. These sensors may be selected according to the cost target and performance requirements of the drone, and may be duplicated or multiplexed. In addition, a sensor may be provided at the base station 404 outside the drone 100, the controller 401, or another place, and the read information may be transmitted to the drone. For example, a wind sensor may be provided in the base station 404, and information regarding wind force/wind direction may be transmitted to the drone 100 via Wi-Fi communication.

The flight controller 501 sends a control signal to the pump 106 to adjust the medicine ejection amount and stop the medicine ejection. It is desirable that the current status of the pump 106 (for example, the number of revolutions) is fed back to the flight controller 501.

The LED 107 is a display means for informing the drone operator of the status of the drone. Display means such as a liquid crystal display may be used instead of or in addition to the LEDs. The buzzer 518 is an output means for notifying a drone state (especially an error state) by a voice signal. The Wi-Fi slave device function 519 is an optional component for communicating with an external computer or the like, for example, for software transfer, in addition to the controller 401. In addition to or in addition to the Wi-Fi cordless handset function, other wireless communication means such as infrared communication, Bluetooth (registered trademark), ZigBee (registered trademark), NFC, or wired communication means such as USB connection May be used. The speaker 520 is an output means for notifying the drone state (particularly, the error state) by the recorded human voice, synthesized voice, or the like. Depending on the weather conditions, it may be difficult to see the visual display of the drone 100 in flight, and in such a case, it is effective to communicate the situation by voice. The warning light 521 is a display means such as a strobe light that informs the drone state (particularly an error state). These input/output means may be selected according to the cost target and performance requirements of the drone, and may be duplicated/multiplexed.

In an agricultural drone that sprays drugs and the like by autonomous flight, maintaining the drone's altitude and the upper limit of its speed is extremely important for maintaining safety. This is because the drone 100 is not always attached to the user 402 by sticking to the controller 401. If the altitude of the drone 100 exceeds a predetermined altitude, the impact at the time of a ground collision in the event of a drop may exceed the safety regulations (in the unlikely event of a collision with a person, serious damage may occur). .. In addition, it is desirable to limit the altitude in order to minimize the drug drift outside the target field. Similarly, if the speed of the drone 100 exceeds a predetermined speed, it may pose a serious safety problem. In addition to falling, the impact of collision with an obstacle (especially human) may exceed the safety standard.

In order to comply with the safety standards, it is desirable that the drone 100 according to the present invention includes an altitude measuring means, a speed measuring means, or both for being an input of the flight controller 501. In addition, a weight measuring means may be provided. It is desirable that the flight controller 501 inputs these measured information and controls the motor 102 so that the drone 100 does not exceed a predetermined limit altitude, a predetermined speed limit, or both.

(Altitude measurement)
The drone 100 according to the present invention preferably uses a plurality of sensors to measure the aircraft altitude. A combination of GPS 504, acceleration sensor 505, barometric pressure sensor 507, sonar 509, and laser sensor 508 may be used to measure altitude. The ground distance may be measured by providing the multi-spectral camera 512 or the obstacle detection camera 513 with a passive autofocus function. In this case, it is desirable that the measuring instruments and sensors be duplicated or multiplexed in case of failure. Duplexing/multiplexing may be performed by using a plurality of sensors of the same type, may be performed by using a plurality of sensors in combination, or may be performed by both of them.

For example, the sonar 509 can make accurate measurements when the field 403 is the ground, but it is difficult to make accurate measurements when the field 403 is the water surface (in this case, the laser sensor 508 is suitable), etc. However, it is desirable to use a plurality of sensors in combination because some measurement methods have advantages and disadvantages. In addition, even if the GPS 504 is multiplexed even if the GPS radio wave is disturbed or the base station is abnormal, it is an obstacle to the whole. Therefore, it is desirable to provide an altitude measuring means other than the GPS.

In particular, it is desirable to use GPS 504 for initial altitude measurement during takeoff and sonar 509 during flight. GPS504 can measure the most accurate, but only absolute altitude can be measured, so accurate ground altitude cannot be measured in field 403 with unevenness such as irrigation canal, whereas Sonar 509 measures the ground altitude because it measures the distance to the ground. Because it can be measured. During level flight, both GPS 504 and sonar 509 measurements are performed and the results are compared, and if the difference is within a predetermined threshold (for example, 10 cm), the GPS 504 measurement is used for altitude measurement and the predetermined threshold is used. When it exceeds, it may be determined that the unevenness of the field 403 is large and the measurement value of the sonar 509 may be used for altitude measurement.

The GPS 504 becomes an indispensable function to grasp the flight position of the drone anyway, so if the GPS 504 does not function due to a failure or disturbance during takeoff, a control (interlock) that prohibits takeoff of the drone It is desirable to do. Also, if GPS stops working during flight due to interruption of radio waves from GPS satellites, temporary interruption of reception, communication interruption, and other inability to receive, drone 100 will fly over the spot. It is desirable to perform control to stop (hover). When the GPS does not function even after the lapse of a predetermined time, the hovering may be stopped and the drone 100 may be controlled to soft land on the spot or return to the departure point 406 or the like. At this time, an error message may be displayed on the pilot 401 and the user 402 may be instructed.

By inputting the altitude information measured by these altitude measurement means to the flight control means of the drone 100, the drone 100 can be controlled within the restricted altitude defined by legal regulations and safety standards, even if it is not operated by human eyes. It will be possible to fly with.

When the altitude is measured by the GPS 504, it is desirable to set the restricted altitude lower than that when the sonar 509 measures the altitude. GPS measures the absolute value of the altitude of the drone 100, while Sonar 509 measures the distance between the drone 100 and the ground surface, so allow a margin for the restricted altitude considering the height of the terrain Is desirable. For example, if the sonar 509 has a restricted altitude of 2 meters, the GPS 504 may have a restricted altitude of 1.5 meters.

In addition to the absolute altitude limit of the drone 100, the rate of climb (the change in altitude over time) may be limited. This is because if the climb speed is not limited, there is a risk that the drone 100 may temporarily exceed the restricted altitude due to a delay in sensor measurement, a delay in processing by the flight controller 501, and the like. In this case, when the altitude is measured by the GPS 504, the upper limit value of the ascending speed may be set lower than the case where the altitude is measured by another method such as the sonar 509. This is because the GPS 504 may temporarily be unable to measure due to the disturbance of radio waves or the situation of positioning satellites, so that the risk of the drone temporarily exceeding the restricted altitude increases.

(Speed limit)
The drone 100 according to the present invention may measure airframe speed using a plurality of sensors. For speed measurement, acceleration sensor 505 (speed can be obtained by integration of acceleration), GPS Doppler 504-3 (airframe speed can be measured by processing the phase difference of radio waves from multiple GPS base stations with software) , Or changes in absolute coordinates measured by GPS 504 may be used. In this case, it is desirable that the measuring instruments and sensors be duplicated or multiplexed in case of failure. Duplexing or multiplexing is preferably performed within the same system and between different systems. This is because, for example, if GPS cannot be used due to radio disturbance or positioning satellite failure, if only GPS is duplicated, it will cause an overall failure.

By inputting the speed information measured by these altitude measuring means to the flight controller 501, the drone 100 is within the speed limit set by the legal regulation, the safety standard, etc. even if the drone 100 is not visually operated (for example, It is possible to fly at a speed of 20 km per hour.

(Weight measurement)
In a typical drone 100 pesticide application case, the weight of the drug would be over 10 kilograms. Since the weight of only the body part is typically about 25 kilograms, there is a large difference in overall weight between the start of spraying and the end of spraying. The altitude and speed of drone 100 may be adjusted in response to changes in overall weight. For example, if the safety standards stipulate the impact force on the surface of the drone 100 when it naturally falls, the impact force is determined by altitude, velocity, and weight (proportional to the square of velocity, proportional to altitude and weight). Therefore, the limit altitude may be increased when the body weight is light. Similarly, when the airframe weight is light, the speed limit may be increased. Further, the limit altitude may be set low when the flight speed is high, and the speed limit may be set low when the flight altitude is high.

The airframe weight may be estimated using the acceleration measured by the acceleration sensor 505 or the acceleration as a differential value of the speed measured by means such as GPS Doppler 504-3 or GPS 504. If the thrust of the motor 102 is T, the gravitational acceleration is g, and the measured acceleration of the airframe is α during the ascent, the weight M of the entire airframe is obtained as M=T/(α+g). The thrust T of the motor 102 is determined by the rotation speed of the motor, and the flight controller 501 can measure the rotation speed of the motor, so that the weight of the airframe can be estimated. When the motor rotation speed cannot be directly measured, the target rotation speed commanded by the flight controller 501 to the motor 102 may be regarded as the motor rotation speed, and the thrust may be estimated from the target rotation speed.

Further, the body weight may be estimated by measuring the inclination of the body of the drone 100 during the uniform horizontal flight. The tilt of the machine body may be directly measured by providing a gyro sensor, or may be estimated by differentiating the measurement value of the 6-axis type acceleration sensor 505 twice. During constant-velocity level flight, the aircraft's air resistance, gravity, and rotor thrust are balanced. Air resistance is a function of aircraft flight speed, thrust by rotor blades is a function of motor speed, and gravity is a function of airframe weight, so weight is the tilt of the airframe, motor speed, airframe If the flight speed of is known, it can be estimated. A wind force sensor may be provided to correct the air resistance coefficient according to the wind force and the wind direction.

In addition, since the largest factor that changes weight during flight is the amount of drug, the level sensor in the drug tank measures the height of the liquid surface of the drug to measure the remaining amount of drug, and then The weight of the entire aircraft may be estimated. In this case, a water pressure sensor may be provided in the medicine tank, and the weight of the medicine in the medicine tank may be estimated to estimate the weight of the entire machine body.

FIG. 6 is a schematic diagram showing the configuration of the failure detection system according to the embodiment of the present invention.
The failure detection system according to the present embodiment is provided in an agricultural machine that sprays a drug, particularly in this example, a drug spray drone 100, and detects a failure in advance. Incidentally, in the present embodiment, the case such as "a state of failure" means that the drug is leaking from a normally managed route, and the check valves 121-1 121-2 121-3. The drone 100 cannot accurately perform the originally intended operation, such as a state where it is not functioning normally.

As described above, the medicine tank 104 is a tank for storing the medicine to be sprayed.
The drug tank 104 is provided with an openable/closable lid for filling the drug and taking out the stored drug. An open/close sensor 104a capable of detecting the open/closed state is attached to the openable/closable lid. The open/close sensor 104a can be configured by, for example, a magnet attached to the lid and a sensor attached to the main body to detect magnetic force and contact of the magnet. This makes it possible to discriminate the open/closed state of the lid and allow the user to recognize the open/closed state of the lid, and prevent a situation in which the medicine is sprayed with the lid open.

Further, the medicine tank 104 is provided with a medicine type discrimination sensor 104b. The drug type determination sensor 104b can determine the type of the drug stored in the drug tank 104.
The drug type discrimination sensor 104b is composed of, for example, a device capable of measuring the viscosity, conductivity, or pH of the drug in the drug tank 104, and the measured value of each item and the reference value for each drug. It is possible to determine the type of drug by comparing with.

Here, since a plurality of types of drugs may be used, it is useful to determine whether or not the drug to be sprayed is stored in the drug tank 104. In particular, the particle size of the drug varies depending on the type.If a drug with a smaller particle size than the drug to be sprayed is accidentally sprayed, a drift (scattering of the drug to other than the target product) , Adhesion), and cannot be overlooked.

Further, the medicine tank 104 is provided with a liquid shortage sensor 511 for detecting liquid shortage of the medicine. It should be noted that the liquid out of the drug includes not only when the drug is exhausted but also when the amount of the drug becomes less than a predetermined amount, and the liquid out of the drug is detected according to an arbitrarily set amount. You can

It is preferable that the drug tank 104 be provided with a function for detecting the evaporation of the drug in the drug tank 104, a temperature/humidity measuring function, and the like so that the drug is managed in an appropriate state.

The pump 106 discharges the medicine stored in the medicine tank 104 to the downstream side, and each medicine nozzle 103-1, 103-2, via medicine hoses 105-1, 105-2, 105-3, 105-4. It is sent to 103-3 and 103-4.
The medicine is delivered from the medicine tank 104 to the medicine nozzles 103-1, 103-2, 103-3, 103-4. In the description of the present embodiment, the medicine is delivered along this delivery path. May be referred to as the downstream direction, and the opposite direction may be referred to as the upstream direction. A part of the medicine is delivered from the medicine tank 104 to the medicine tank 104 again via the three-way valve 122. Regarding this path, the three-way valve 122 side is referred to as the downstream direction and the medicine tank 104 side is referred to as the upstream direction. There is.

The expansion tank 141 is a tank for temporarily storing the medicine delivered from the three-way valve 122 and returning it to the medicine tank 104.
The path from the three-way valve 122 to the medicine tank 104 via the expansion tank 141 is a path for removing (deaerating) air (air bubbles) in the medicine. By circulating this path and temporarily storing it in the expansion tank 141, it is possible to defoam the drug.

The check valves 121-1, 121-2, 121-3 are valves for delivering a drug only in a fixed direction and preventing an inflow in a direction opposite to the fixed direction, that is, a reverse flow. Also, the check valves 121-1 121-2 121-3 block the discharge of the medicine in the path from the medicine tank 104 to the medicine nozzles 103-1, 103-2, 103-3 and 103-4. When the drone 100 is not in the operating state for spraying the medicine, the discharge of the medicine is regulated. For example, the state in which the drone 100 flies, until the drone 100 receives a drug spraying command, the drone 100 is in an abnormal state, the drone 100 receives a command to regulate the drug spraying, and the main drive power is stopped. In a state or the like, the discharge of the medicine is blocked.

In this example, between the medicine tank 104 and the pump 106, between the three-way valve 122 and the medicine nozzles 103-1, 103-2, 103-3, 103-4, between the three-way valve 122 and the expansion tank 141, respectively, the reverse valves are provided. Stop valves 121-1, 121-2, 121-3 are provided. The check valve 121-1 causes the medicine delivered from the medicine tank 104 to be delivered in the downstream direction, and controls the backflow into the medicine tank 104 such that it cannot flow backward. Further, the check valve 121-2 controls the medicine delivered from the pump 106 in the downstream direction, and controls the pump 106 so that it cannot backflow. In addition, the check valve 121-3 controls the three-way valve 122 so that the medicine is delivered in the upstream direction where the expansion tank 141 is located and that the three-way valve 122 cannot be back-flowed. These check valves 121-1, 121-2, 121-3 are normally closed (NC: normally closed) and open according to the discharge pressure of the medicine discharged from the medicine tank 104.

Further, the check valves 121-1, 121-2, 121-3 are predetermined in the route from the medicine tank 104 to the discharge ports 103a-1, 103a-2, 103a-3, 103a-4 to the outside of the medicine. It is provided for each permissible leakage amount. That is, the volume of the path between the one check valve 121-1, 121-2, 121-3 and the check valve 121-1, 121-2, 121-3 adjacent in the upstream direction or the downstream direction is , It is less than the specified allowable leakage.

Further, the path between the check valve 121-1 and the discharge port of the medicine of the medicine tank 104 on the upstream side, the check valve 121-2 and the discharge ports 103a-1, 103a-2, 103a-3 on the downstream side thereof. , 103a-4, the volume is less than or equal to a predetermined allowable leakage amount.

Here, the allowable leakage amount, even if the leaked drug is locally sprayed to the field 403 at one time, the upper limit of the amount of the drug concentration in the sprayed agricultural products or the like, or the leaked drug Even if the drug is sprayed to the field 403, it means the upper limit of the amount that does not affect the surrounding environment at the time of spraying.

In this example, the check valve 121-1 is provided between the medicine tank 104 and the pump 106 and near the medicine discharge port provided in the medicine tank 104. The check valve 121-1 controls the medicine delivered from the medicine tank 104 in the downstream direction so as not to backflow into the medicine tank 104.
The check valve 121-2 is provided between the three-way valve 122 and the drug nozzles 103-1, 103-2, 103-3, 103-4. The check valve 121-2 causes the medicine delivered from the pump 106 to be delivered in the downstream direction and controls the pump 106 so that it cannot backflow.
The check valve 121-3 is provided between the three-way valve 122 and the expansion tank 141. The check valve 121-3 causes the medicine delivered from the three-way valve 122 to be delivered in the upstream direction where the expansion tank 141 is located, and controls the three-way valve 122 so that the backflow cannot be performed.

As the check valves 121-1, 121-2, 121-3, various types such as swing type, lift type, and wafer type can be used, and the check valves are not limited to particular ones. Also, regardless of this example, more check valves than this example may be provided at appropriate locations.

Not limited to the check valves 121-1, 121-2, 121-3, in the path from the drug tank 104 to the drug nozzles 103-1, 103-2, 103-3, 103-4, the discharge of the drug is performed. As long as it can play a role of blocking, another mechanism such as a solenoid valve can be used as the blocking mechanism.

As a result, even if a drug leak occurs in the route from the drug tank 104 to the discharge ports 103a-1, 103a-2, 103a-3, 103a-4, the check valves 121-1, 121-2, When 121-3 closes, the drug contained in the path between the check valves 121-1, 121-2, 121-3 adjacent in the upstream direction or the downstream direction only leaks. Since the amount of the drug that leaks is less than the allowable leak amount, it is safe even if the drug leaks to the outside.

The three-way valve 122 is provided between the pump 106 and the drug nozzles 103-1, 103-2, 103-3, 103-4, and the pump 106 drives the drug nozzles 103-1, 103-2, 103-3, A branch point of the route connecting to 103-4 and a route connecting the pump 106 to the drug tank 104 via the expansion tank 141 is configured, and the drug is delivered to each route according to the switching operation.
Here, the path from the pump 106 to the medicine nozzles 103-1, 103-2, 103-3, 103-4 is such that the medicine is discharged from the medicine nozzles 103-1, 103-2, 103-3, 103-4. , A route for spraying the drug.
Further, as described above, the path from the pump 106 to the medicine tank 104 via the expansion tank 141 is a path for removing (defoaming) bubbles in the medicine.

The flow rate sensor 510 is provided between the pump 106 and the medicine nozzles 103-1, 103-2, 103-3, 103-4, and delivers it to the medicine nozzles 103-1, 103-2, 103-3, 103-4. The flow rate of the drug being measured is measured. Based on the flow rate of the drug measured by the flow sensor 510, the amount of the drug sprayed on the field 403 can be grasped.

The pressure sensors 111-1, 111-2 measure the ejection pressure of the medicine at the attachment position.
The pressure sensor 111-1 is mounted on the downstream side of the pump 106 and on the upstream side of the check valve 121-2 and the three-way valve 122, and measures the discharge pressure of the medicine discharged downstream.
The pressure sensor 111-2 is attached to the downstream side of the check valve 121-2 and the upstream side of the drug nozzles 103-1, 103-2, 103-3, 103-4, and the Measure the discharge pressure.

Since it is possible to measure the discharge pressure of the drug by these pressure sensors 111-1, 111-2, 111 of each pressure sensor with the check valves 121-1, 121-2, 121-3 closed. The failure can be detected by acquiring the change over time of the discharge pressure of the medicine measured by -1, 111-2 and comparing this with the change over time of the discharge pressure of the medicine under normal conditions. For example, when the discharge pressure of the drug acquired by the pressure sensors 111-1, 111-2 draws a downward line with time, and this downward line exceeds the error range and is different from the normal time, It can be inferred that there is a failure such as leakage of the drug.

Further, by making a determination for each of the pressure sensors 111-1, 111-2, it is possible to roughly specify the position where the failure has occurred, such as the path through which the drug has leaked. That is, in this example, when it is determined that the measured value of the pressure sensor 111-1 is normal, while the measured value of the pressure sensor 111-2 is abnormal, the pressure sensor 111-1 is downstream of the pressure sensor 111-1. It can be inferred that a failure has occurred.

The pump sensor 106a measures the rotation speed of the rotor that sucks the drug from the drug tank 104 and discharges the drug downstream in the pump 106.
Whether or not the rotation speed of the rotor of the pump 106 is measured by the pump sensor 106a and then compared with the discharge pressure of the medicine measured by the pressure sensors 111-1, 111-2, and whether or not the ratio in the normal state matches The failure can be detected by determining That is, when the discharge pressure of the medicine according to the rotation speed of the pump 106 is not obtained as compared with the normal time, it is estimated that the medicine leaks and the discharge pressure is reduced.

The nozzle type discrimination sensors 104-1, 104-2, 104-3, 104-4 are drug nozzles 103-1, 103 attached to the drug ejection ports 103a-1, 103a-2, 103a-3, 103a-4. The type of -2, 103-3, 103-4 can be discriminated.
Due to the difference in particle size for each drug to be sprayed, the drug nozzles 103-1, 103-2, 103-3, 103-4 are usually different depending on the drug. Therefore, by deciding whether or not the type of the medicine nozzles 103-1, 103-2, 103-3, 103-4 is appropriate, it is possible to prevent erroneous medicine spraying.

Specifically, for example, a mechanism for fitting or engaging the drug nozzles 103-1, 103-2, 103-3, 103-4 is provided in the discharge port, and the drug nozzles 103-1, 103-2, 103 are provided. -3, 103-4 is a mechanism for fitting or engaging with the fitting or engaging mechanism on the outlet side, and a plurality of medicine nozzles 103-1, 103-2, 103-3, 103-4 A different shaped mechanism is provided for each. Then, when the medicine nozzles 103-1, 103-2, 103-3, 103-4 are attached to the ejection ports, different shapes are identified for each medicine nozzle 103-1, 103-2, 103-3, 103-4. By doing so, it is possible to determine the type of the medicine nozzles 103-1, 103-2, 103-3, 103-4.
This makes it possible to prevent the drift of the drug from being caused by using a drug having a particle diameter smaller than that of the drug to be used.

In the middle of the route from the drug tank 104 to the drug nozzles 103-1, 103-2, 103-3, 103-4, a discharge port with a cock for discharging the drug stored in the route to the outside. (In FIG. 6, it is described as “DRAIN”). When the drug accumulated in the route from the drug tank 104 to the drug nozzles 103-1, 103-2, 103-3, 103-4 is to be discharged after the spraying of the drug on the field 403 is completed, The medicine can be discharged from this discharge port.

In the present embodiment, as shown in FIG. 7, the flight controller 501 has a determination processing unit 11 for detecting a failure, an information storage unit 32 storing data necessary for the determination process, and a check valve 121- The control unit 12 controls the opening/closing operation of 1 and 121-2 and the spraying operation of the medicine.

Here, the control unit 12 causes the drone 100 to take a predetermined safety action when it is determined that a failure has occurred as a result of the determination processing by the determination processing unit 11 described later.
Here, the predetermined safety action is an evacuation action during flight, and a drug spraying control measure or flight control measure in a preparatory state before flight.

The evacuation action includes, for example, a normal landing operation, an aerial stop such as hovering, and an "emergency return" in which the vehicle immediately moves to a predetermined return point by the shortest route. The predetermined return point is a point stored in advance in the flight controller 501, for example, a point at which the flight controller 501 has taken off. The predetermined return point is, for example, a land point where the user 402 can approach the drone 100, and the user 402 can inspect the drone 100 reaching the return point or manually carry it to another place. can do.
Further, the evacuation action may be a “normal return” in which the route is optimized to move to a predetermined return point. The optimized route is, for example, a route calculated by referring to the route in which the medicine is sprayed before receiving the normal return command. For example, the drone 100 moves to a predetermined return point while spraying the drug via a route that has not yet sprayed the drug.
Further, the evacuation action includes an “emergency stop” in which all the rotor blades are stopped and the drone 100 is dropped downward from the place.

The flight control measure is a measure for restricting the flight in the preparatory stage before flight, and is for rejecting the flight order of the user or requesting the user to confirm the state.
If flight control measures are taken, the aircraft may be controlled so that it cannot fly unless an abnormality is confirmed or maintenance is performed.

The control unit 12 is not limited to the case where an abnormality occurs in the drone 100, and can control the discharge amount and flow rate to a predetermined value based on the discharge amount and flow rate of the medicine measured by each sensor.

The functions directly required for the processing executed by the judgment processing unit 11 are as shown in FIG. 7, and by these functional units, the first judgment processing unit 11 performs the following first and second judgment processing. Can be performed. The flow of each determination process is as shown in FIG. 8, and each process will be described based on this.
The processing by the determination processing unit 11 is executed before the flight of the drone 100, that is, in the preparation state for spraying the drug. That is, the user of the drone 100 confirms the safety of the drone 100 in advance and then sprays the drug using the drone 100.

Judgment processing unit 11, as the first judgment processing, in the state where the check valves 121-1 and 121-2 are closed, the discharge pressure of the drug measured by the pressure sensors 111-1 and 111-2 over time. The change in the discharge pressure of the acquired medicine with time and the change in the discharge pressure of the medicine in the normal time stored in the information storage unit 32 to determine whether there is a failure. be able to.

That is, the determination processing unit 11 acquires the change over time of the ejection pressure of the drug as the status (S101), and compares the change over time in the normal state stored in the information storage unit 32 to determine whether a failure has occurred. It is determined whether or not (S102). As a result, when it is determined that a failure has occurred, the control unit 12 takes flight control measures, drug dispersion control measures, or use control measures (S103).
Here, flight control measures, use control measures, or spray control measures are measures for controlling flight, use, or autonomous driving, such as rejecting the flight command of the user or requesting the user to confirm the state. To do. The check valves 121-1, 121-2, 121-3 may be forcedly closed. When flight control measures or drive control measures are taken, the aircraft may be controlled so that it cannot fly unless an abnormality is confirmed or maintenance is made. In this respect, the same applies to the second determination process described below.

Note that, regarding this first determination process, not only the change over time of the discharge pressure of the drug measured by each pressure sensor 111-1, 111-2, but also measured by each pressure sensor 111-1, 111-2. The failure can also be determined based on the change over time in the pressure loss calculated from the discharge pressure.

Further, as the second determination process, after measuring the number of rotations of the rotor of the pump 106 by the pump sensor 106a, the ratio compared with the discharge pressure of the drug measured by the pressure sensor 111-1, 111-2 It is possible to determine the failure by determining the value of “1” and determining whether or not it matches the normal ratio stored in the information storage unit 32.

That is, the determination processing unit 11 acquires the rotation speed of the rotor of the pump 106 and the discharge pressure of the medicine measured by the pressure sensors 111-1 and 111-2 as statuses (S101). Then, these are compared and the ratio thereof is calculated, and the failure is judged by whether or not it matches the normal ratio stored in the information storage unit 32 (S102). As a result, when it is determined that there is a failure, flight restriction measures or drive restriction measures are taken (S103).

Even if the number of rotations of the rotor of the pump 106 is independent, it can be determined that the failure occurs when the number of rotations is less than the required amount by comparing with the required discharge amount.

When a failure is detected as a result of the determination processing by the determination processing unit 11 as described above, the flight controller 501 executes an operation for ensuring safety. Specifically, when a failure is detected, the flight controller 501 sends a control signal to the pump 106 to stop the discharge of the medicine and close the check valves 121-1 and 121-2, Keep the valve closed. Further, the flight command from the user 402 may be restricted until the failure is resolved.

In the failure detection system, regardless of the above, the discharge pressure of the medicine measured by the pressure sensors 111-1, 111-2, the discharge of the medicine measured by the pressure sensor 111-1 and the pressure sensor 111-2. A failure is determined by combining any one of the pressure loss calculated from the pressure difference, the rotation speed of the rotor inside the pump 106 measured by the pump sensor 106a, and the drug flow rate measured by the flow rate sensor 510. Can also For example, the rotation speed of the rotor in the pump 106, the flow rate of the drug measured by the flow rate sensor 510, the discharge pressure of the drug measured by the pressure sensors 111-1, 111-2, and the pump measured by the pump sensor 106a. The rotation speed of the rotor in 106, or the pressure loss calculated from the difference between the discharge pressures of the medicines measured by the pressure sensor 111-1 and the pressure sensor 111-2 and the flow rate of the medicine measured by the flow rate sensor 510. , Using a plurality of detection information. By comparing the information acquired by these plural sensors, it is possible to judge the ejection abnormality of the medicine from the ratio. For example, if the discharge pressure measured by the pressure sensors 111-1 and 111-2 is smaller or larger than the normal value with respect to the flow rate of the medicine measured by the flow sensor, a medicine discharge abnormality may occur. You can determine that This makes it possible to determine the presence or absence of a failure.

In addition to the above control, the flight controller 501 can also take flight control measures when a failure (abnormal state) of the drone 100 is detected (S201), as shown in FIG. 9 (S202). ..

For example, based on the information from the open/close sensor 104a attached to the lid of the drug tank 104 and capable of detecting the open/closed state, the open state of the lid is regarded as a failure, which is detected, and flight control measures are taken. You can also

Further, in addition to the check valves 121-1 and 121-2, the leakage of the drug was detected at the discharge port of the drug tank 104 and the drug nozzles 103-1, 103-2, 103-3, 103-4. At times, a blocking mechanism for forcibly blocking the discharge or delivery of the medicine may be provided separately.

The failure detection performed by each sensor and the determination processing unit 11 is performed as an inspection at a preparatory step for spraying chemicals, that is, a step before flying the drone 100, but the drone 100 is allowed to fly regardless of this. Also, it may be configured such that it is continuously or intermittently executed at a predetermined timing even when the medicine is sprayed to the field 403.

In addition, in the present embodiment, before the use of the drone 100, the detection processing of the failure by the determination processing unit 11 is always executed, and unless the failure is detected and it is shown that it can be used safely, it depends on the user. The use may be restricted, for example, by refusing to order the drone 100 to fly or spray the drug.

In addition, as a confirmation process at the preparatory stage before flight together with the failure detection, the status related to the disturbance factors such as wind speed, temperature, and humidity may be used as basic data for the determination to determine whether or not the flight is possible. For these statuses, the faster the wind speed is, the more likely it is that the drug will be scattered to the destination. Regarding the temperature and humidity, the higher the temperature and the lower the humidity, the more easily the sprayed drug itself dries, and as a result of evaporation of the water content of the drug sprayed in the field 403, particles of the dry drug Are likely to be scattered outside the field 403.
In order to obtain these statuses, the drone 100 is equipped with a wind speed measuring means and a temperature/humidity measuring means.

As a specific determination process, it is possible to determine whether or not flight is possible based on the wind speed measured by the wind speed measuring means. Specifically, if the wind speed measured by the wind speed measuring means is equal to or higher than a predetermined speed, it can be determined that the flight is impossible.

That is, the information regarding the wind speed is acquired as the status, and it is determined whether or not the flight is possible by comparing with the predetermined value stored in the information storage unit. As a result, if it is determined that flight is impossible, it is advisable to take measures to restrict flight.

Further, based on the temperature and humidity measured by the temperature and humidity measuring means, it is possible to determine whether or not flight is possible (whether or not a drug can be sprayed). Specifically, regarding the temperature and humidity measured by the temperature and humidity measuring means, when the temperature is equal to or higher than a predetermined value and the humidity is equal to or lower than a predetermined value, it can be determined as an abnormal state.

That is, the second determination processing unit acquires information related to temperature and humidity as a status (S201), and determines whether or not flight is possible by comparing with a predetermined value stored in the threshold value information storage unit (S202). As a result, if it is determined that flight is impossible, it is advisable to take measures to restrict flight. The temperature/humidity measuring means may be included in the drone 100 itself, but may be included in a base station for communication or around the farm field 403 and may be acquired by the drone 100 through communication.

Alternatively, the air contained in the medicine may be detected, and the air may be bleed when the air exceeds the allowable range.
Whether or not the air contained in the medicine is within the allowable range is, for example, information relating to the actual flow rate of the medicine is acquired by the flow rate sensor 510, and the flow rate by the determination processing unit 11 and the medicine to be delivered according to the setting. It is determined whether or not it falls within a predetermined allowable range by comparing with the flow rate of. Normally, when the drug contains a large amount of air, the flow rate is reduced as compared with the setting, and thus the determination can be made by such processing. Further, the air bleeding can be performed by circulating the medicine in a route from the three-way valve 122 to the medicine tank 104 via the expansion tank 141 and temporarily storing the medicine in the expansion tank 141.

An example of the specific processing is shown in FIG.
That is, the flow rate sensor acquires the flow rate information of the chemical liquid (S301). Depending on the child, the determination processing unit 11 compares the flow rate information with the flow rate of the designated or set medicine, and determines whether the error is within the allowable range (S302). As a result, if the error is within the allowable range, the drug solution is sprayed as normal.
On the other hand, if the error is outside the allowable range, the air is bleed until normal (S303).

In the above embodiment, the flight controller 501 of the drone 100 is provided with the determination processing unit 11, but the present invention is not limited to this, and a server or the like that obtains data from the flight controller 501 via a predetermined communication line is concerned. A determination processing unit may be provided so that the determination processing may be executed by the server or the like.

Although the embodiment of the drone for the purpose of spraying the drug has been described, the present invention is also applicable to an agricultural drone that does not spray the drug and monitors growth by a camera, and a general drone.

(Technically remarkable effect of the present invention)
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to reliably detect a failure in advance and improve safety in an agricultural machine that sprays a medicine. In particular, it can be detected automatically and immediately by a sensor.
Further, the present system can be widely applied to various agricultural machines that spray medicines.

Claims (12)

A system for detecting a failure, which is provided in an agricultural machine that sprays chemicals,
A pressure sensor provided in a route from a drug tank for storing the drug to a discharge port of the drug;
Failure detection means for detecting a failure of the agricultural machine,
The failure detection means acquires a change over time in the discharge pressure of the medicine by the pressure sensor, and detects a failure based on the change over time in the discharge pressure of the acquired medicine.
Failure detection system. The agricultural machine is provided with a blocking mechanism that blocks a path from the medicine tank to the discharge port,
The failure detection unit acquires a change over time in the discharge pressure of the drug by the pressure sensor in a state in which the path from the drug tank to the discharge port is blocked by the blocking mechanism, and the acquired discharge pressure of the drug is acquired. Failure is detected based on the change of
The failure detection system according to claim 1. The shutoff mechanism is a check valve,
The failure detection system according to claim 2. The shutoff mechanism is a solenoid valve,
The failure detection system according to claim 2. The failure detection unit detects a failure based on a change with time of the discharge pressure of the medicine by the pressure sensor and a change with time of the discharge pressure of the medicine at a normal time,
The failure detection system according to any one of claims 1 to 4. A plurality of the pressure sensors,
The failure detection means detects a failure based on a temporal change in pressure loss calculated from the discharge pressure acquired by the plurality of pressure sensors,
The failure detection system according to any one of claims 1 to 5. The agricultural machine is provided with a pump for discharging the medicine stored in the medicine tank to the downstream,
A pump sensor for measuring the number of rotations of a rotor that sucks the drug from the drug tank and discharges the drug downstream in the pump,
The failure detection unit detects a failure based on the rotational speed of the rotor of the pump measured by the pump sensor and the change over time in the ratio of the discharge pressure of the drug measured by the pressure sensor,
The failure detection system according to any one of claims 1 to 6. When a failure is detected by the failure detection means, further comprising control means for causing the agricultural machine to take a predetermined safety action,
The failure detection system according to any one of claims 1 to 7. The predetermined safety action is a control for retracting the agricultural machine during chemical spraying of the agricultural machine, and regulation of chemical spraying by the agricultural machine in a preparatory step before spraying chemicals on the agricultural machine. Or a control that regulates the use of the agricultural machine,
The failure detection system according to claim 8. The agricultural machine is a drone,
The failure detection system according to any one of claims 1 to 9. A method carried out by a system for detecting a failure, which is provided in an agricultural machine for spraying a drug, comprising:
The system is
Acquiring a change over time of the discharge pressure of the drug by a pressure sensor provided in the path from the drug tank storing the drug to the discharge port of the drug, based on the change over time of the discharge pressure of the acquired drug, Detecting a failure of the agricultural machine,
Failure detection method. A computer program executed by a system for detecting a failure, which is provided in an agricultural machine for spraying a drug, comprising:
For the system,
Acquiring a change over time of the discharge pressure of the drug by a pressure sensor provided in the path from the drug tank storing the drug to the discharge port of the drug, based on the change over time of the discharge pressure of the acquired drug, Detect a failure of the agricultural machine,
Computer program.

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