Method and device for calibrating flowmeter of plant protection unmanned aerial vehicle

Abstract

A method for calibrating a flowmeter of a plant protection unmanned aerial vehicle, comprising: acquiring first mass of a pesticide tank and first number of pulses of a flowmeter before operation of the plant protection unmanned aerial vehicle, and acquiring second mass of the pesticide tank and second number of pulses of the flowmeter after the operation of the plant protection unmanned aerial vehicle (S210); determining that a pesticide tank mass change value is greater than a first threshold and a number-of-pulses change value is greater than a second threshold (S220); calculating a pulse coefficient of the flowmeter on the basis of the pesticide tank mass change value and the number-of-pulses change value (S230); acquiring n historical pulse coefficients (S240); and determining a calibration pulse coefficient of the flowmeter on the basis of the pulse coefficient and the n historical pulse coefficients, and using the calibration pulse coefficient to update the pulse coefficient of the flowmeter (S250). The present invention further comprises a device for calibrating a flowmeter of a plant protection unmanned aerial vehicle, and a plant protection unmanned aerial vehicle.

Description

Calibration method and device for flowmeter of plant protection drone

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on September 14, 2023, with application number 202311187122.1 and invention name “Calibration Method and Device for Flow Meter of Plant Protection UAV”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of plant protection drones, and specifically to a method and device for calibrating a flow meter of a plant protection drone. Background Art

[0003] To increase crop yields, using drones for agricultural pesticide spraying has become a crucial step in the agricultural production process. A flowmeter is a device installed on a drone sprayer to measure pesticide flow or velocity. A pulse flowmeter is a common instrument used on drones to measure pesticide flow by counting pulses. The impulse of the pesticide drives blades in a magnetic field, inducing electrical pulse signals at both ends of the coil. These pulse signals are amplified and shaped before being sent to a controller, which determines the pesticide flow rate based on the number of pulses within a certain period. The relationship between pesticide flow rate and the number of pulses is Q = k0N, where Q is the flow rate, N is the number of pulses, and k0 is the calibration pulse coefficient, a fixed value that is calibrated at the factory, allowing users to directly use the flowmeter to measure pesticide flow.

[0004] When using a drone for agricultural protection, the spraying system and the type of pesticide sprayed can affect the sensitivity and accuracy of the flow meter, leading to inaccurate measurement data and impacting the effectiveness of the operation. Therefore, the flow meter's pulse coefficient must be calibrated before any operation. A static calibration method is typically used: the drone sprays a fixed amount of clean water on the ground and calculates the mass of clean water per pulse, i.e., the calibration pulse coefficient. This is then used to update the calibrated pulse coefficient. Considering test time and efficiency, this method uses less water during testing, resulting in test results that are subject to sensor fluctuations. Furthermore, since the sprayed liquid is clean water, its viscosity and fluidity differ from the actual sprayed pesticide solution. Consequently, the calibration pulse coefficient will also differ, resulting in inaccurate measurement data during actual operation. Therefore, improving the accuracy of flow meter calibration on drones for agricultural protection is an urgent issue.

[0005] Summary of the Invention

[0006] The present application provides a method and device for calibrating a flow meter for a plant protection drone. This method determines the calibration pulse coefficient of the flow meter based on multiple measurement results after meeting certain calibration conditions, which can effectively improve the accuracy of the calibration pulse coefficient. The highly accurate calibration pulse coefficient is used to determine the actual spraying volume of the plant protection drone and the target number of pulses required to complete the spraying of a certain amount of liquid medicine. This enables users to accurately control the spraying process and effectively improves the operating effect of the plant protection drone.

[0007] In a first aspect, a method for calibrating a flow meter of a plant protection drone is provided, comprising:

[0008] Obtain the first mass of the medicine box and the first pulse number of the flow meter before the plant protection drone operates, and obtain the second mass of the medicine box and the second pulse number of the flow meter after the plant protection drone operates; determine whether the change value of the medicine box mass is greater than the first threshold and the change value of the pulse number is greater than the second threshold, and calculate the pulse coefficient of the flow meter according to the change value of the medicine box mass and the change value of the pulse number, wherein the change value of the medicine box mass is the difference between the first mass and the second mass, and the change value of the pulse number is the difference between the second pulse number and the first pulse number; obtain n historical pulse coefficients, determine whether the standard deviation of the pulse coefficient and the n historical pulse coefficients is less than a third threshold, and determine the calibration pulse coefficient of the flow meter according to the pulse coefficient and the n historical pulse coefficients; wherein the n historical pulse coefficients are obtained respectively in n historical operation processes at different time points, and the n historical operation processes are performed under different working conditions; use the calibration pulse coefficient to update the pulse coefficient of the flow meter, wherein the pulse coefficient calculation formula is: pulse coefficient = medicine box mass change value ÷ pulse number change value. Among them, the first threshold refers to the minimum value of the medicine box mass change value set manually, the second threshold refers to the minimum value of the pulse number change value set manually, and the third threshold refers to the maximum value of the standard deviation of the manually set pulse coefficient and n historical pulse coefficients.

[0009] Due to the limited sensitivity of the flowmeter and mass sensor, when the mass of the liquid medicine is too small, the error between the mass of the medicine box and the pulse count of the flowmeter is large. Therefore, the embodiment of the present application only calibrates the pulse coefficient of the flowmeter when the mass change value is greater than a first threshold and the pulse count change value is greater than a second threshold, which can effectively improve the calibration accuracy of the flowmeter pulse coefficient.

[0010] When the standard deviation of the pulse coefficient and the n historical pulse coefficients is less than the third threshold, it indicates that the flow meter measurement results are relatively stable during the operation of the plant protection UAV, and are used to calculate the calibration pulse coefficient, which can improve the accuracy of the calibration pulse coefficient.

[0011] In some possible embodiments, the standard deviation of the pulse coefficient and n historical pulse coefficients is less than a third threshold, and the calibration pulse coefficient of the flow meter is determined based on the pulse coefficient and n historical pulse coefficients, including: the calibration pulse coefficient is the arithmetic mean of the pulse coefficient and the n historical pulse coefficients.

[0012] In some possible embodiments, the standard deviation of the pulse coefficient and n historical pulse coefficients is less than a third threshold, and the calibration pulse coefficient of the flow meter is determined based on the pulse coefficient and the n historical pulse coefficients, including: the calibration pulse coefficient is the weighted average of the pulse coefficient and the n historical pulse coefficients, wherein the weight of each pulse coefficient is the number of times each pulse coefficient appears.

[0013] In some possible embodiments, if the standard deviation of the pulse coefficient and n historical pulse coefficients is greater than or equal to a third threshold, the pulse coefficient is not recorded and the calibration pulse coefficient is not updated.

[0014] The embodiment of the present application uses the pulse coefficient calculated after multiple operations to calibrate the pulse coefficient of the flow meter, which can improve the calibration accuracy. The use of weighted average can further eliminate the influence of extreme values ​​on the calibration pulse coefficient, thereby improving the accuracy of the calibration pulse coefficient.

[0015] In some possible embodiments, the method further includes: obtaining a preset collection duration; obtaining a third pulse number corresponding to the first moment and a fourth pulse number corresponding to the second moment recorded when the plant protection UAV is operating, wherein the interval between the first moment and the second moment is the collection duration; determining the average flow rate within the collection duration based on the calibration pulse coefficient, the third pulse number and the fourth pulse number, wherein the calculation formula for the average flow rate is: average flow rate = (fourth pulse number - third pulse number) × calibration pulse coefficient ÷ collection duration.

[0016] By calculating the average flow rate during the acquisition period, users can more accurately observe the actual spraying conditions of the plant protection drone.

[0017] In some possible embodiments, the method further includes calculating the actual spraying amount according to the calibrated pulse coefficient and the number of pulses of the flow meter. The calculation formula of the actual spraying amount is: actual spraying amount = calibrated pulse coefficient × number of pulses.

[0018] In an embodiment of the present application, when the plant protection drone is operating, the actual spraying amount can be calculated in real time by obtaining the pulse number of the flow meter and the calibration pulse coefficient, so that the user can obtain the actual spraying amount in real time, thereby more accurately controlling the operation process of the plant protection drone.

[0019] In some possible embodiments, the method further includes: calculating a target pulse number based on a preset spraying amount and a calibration pulse coefficient, wherein the target pulse number is calculated using the formula: target pulse number = preset spraying amount / calibration pulse coefficient.

[0020] In an embodiment of the present application, the target number of pulses required to spray a preset amount of liquid medicine can be determined based on the preset spraying volume and the calibrated pulse coefficient, so that the operation can be stopped after reaching the target number of pulses. This can accurately control the operation time of the plant protection drone and effectively improve the operation effect of the plant protection drone.

[0021] In a second aspect, a flow meter calibration device for a plant protection drone is provided, comprising:

[0022] The acquisition module is used to obtain the first mass of the medicine box and the first pulse count of the flow meter before the plant protection drone is operating, and to obtain the second mass of the medicine box and the second pulse count of the flow meter after the plant protection drone is operating. It is also used to obtain n historical pulse coefficients, a first threshold, and a second threshold. The n historical pulse coefficients were obtained during n historical operations at different time points, and the n historical operations were performed under different working conditions. The calculation module is used to calculate the change in the medicine box mass based on the first mass and the second mass, calculate the change in the pulse count based on the first pulse count and the second pulse count, and determine whether the change in the medicine box mass is greater than the first threshold and the change in the pulse count is greater than the second threshold. It is then used to calculate the pulse coefficient of the flow meter based on the change in the medicine box mass and the change in the pulse count. It is also used to determine the calibration pulse coefficient of the flow meter based on the pulse coefficient and the n historical pulse coefficients. The control module is used to control the plant protection drone to perform weighing operations before and after the operation to obtain the first mass and the second mass. The calibration module is configured to update the flow meter's pulse coefficient using the calibration pulse coefficient. The module is also configured to obtain a third threshold, a preset collection duration, and a third pulse count corresponding to a first moment and a fourth pulse count corresponding to a second moment recorded during operation of the plant protection drone, where the interval between the first moment and the second moment is the collection duration. The calculation module is further configured to execute the method according to the embodiment of the first aspect.

[0023] In some possible embodiments, the calculation module is also used to determine the average flow rate within the acquisition time based on the calibration pulse coefficient, the third pulse number and the fourth pulse number, where the calculation formula for the average flow rate is: average flow rate = (fourth pulse number - third pulse number) × calibration pulse coefficient ÷ acquisition time.

[0024] In a third aspect, a plant protection drone is provided, comprising the device in the second aspect and its embodiments.

[0025] In a fourth aspect, a chip system is provided, comprising a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program from the memory, so that a plant protection drone flow meter calibration device equipped with the chip system executes the method in the above-mentioned first aspect and its implementation method.

[0026] In a fifth aspect, a computer program product is provided, which includes: a computer program code, which, when executed, enables the plant protection drone flow meter calibration device to execute the method in the above-mentioned first aspect and its implementation method.

[0027] In a sixth aspect, a computer-readable storage medium is provided, which stores a program that enables a plant protection drone flow meter calibration device to execute the method in the above-mentioned first aspect and its implementation method.

[0028] The embodiment of the present application provides a flow meter calibration method for a plant protection drone. After the plant protection drone meets certain calibration conditions, it determines the calibration pulse coefficient of the flow meter based on multiple measurement results, effectively improving the accuracy of the calibration pulse coefficient. Based on the determined calibration pulse coefficient, the actual spraying amount of the plant protection drone and the target number of pulses required to complete the spraying of a certain amount of liquid medicine can be calculated, thereby enabling the user to accurately control the operation process and effectively improving the operation effect of the plant protection drone. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a flow chart of a flow meter pulse coefficient calibration method.

[0030] FIG2 is a flow chart of a method for calibrating a flow meter of a plant protection drone according to an embodiment of the present application.

[0031] FIG3 is a structural block diagram of a flow meter calibration device for a plant protection UAV according to an embodiment of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings. The embodiments of the present application are only used to explain the present application, but should not constitute any limitation to the embodiments of the present application.

[0033] Agricultural drones consist of a flight platform, control system, power system, and spraying or spreading system. They can be remotely controlled by ground personnel or autonomously operated by the flight control system to perform tasks such as spraying pesticides, seeds, and fertilizers. The flight platform serves as the foundation for each module, providing a framework for the various systems and providing mounting interfaces for the power system, control system, spraying system, and onboard equipment. The flight platform primarily consists of the fuselage, arms, motor mount, tripod, battery rack, cargo rack, and chassis. The arms connect the fuselage to the power system; the motor mount provides a base platform for the power system; the tripod supports the drone and ensures a safe landing; the battery rack and cargo rack securely mount the battery and cargo box, respectively; and the chassis protects the internal modules from water and dust. The control system primarily includes a central control module, GPS, and remote control. The central control module is the core system that establishes communication between the remote control and the drone, enabling remote control and completing the entire flight process, including takeoff, flight, and mission execution. The GPS is used to obtain latitude and longitude location information; and the remote control controls pitch, roll, yaw, and elevation. The power system provides lift for the drone's flight, enabling various motions. It primarily includes propellers, motors, electronic speed controllers, and batteries. The spraying or sowing system is used to apply pesticides, seeds, and fertilizers according to the control system's instructions. Specifically, the spraying system is equipped with a flow meter that measures the pesticide flow rate or velocity and feeds the results back to the control system. The control system then adjusts the spraying system's spray rate accordingly.

[0034] A pulse flowmeter is a common instrument used on agricultural drones to measure liquid flow by counting pulses. Its operating principle is as follows: a pulse flowmeter consists of at least a sensor housing, an impeller, blades, and a signal detector. As liquid flows through the sensor housing, the impeller blades are angled to the flow direction, creating a rotational torque. The blades rotate after overcoming friction and liquid resistance, and the rotational speed stabilizes once the torques are balanced. Under certain conditions, the rotational speed is proportional to the flow rate. Because the blades are magnetically conductive and located within the magnetic field of a signal detector (composed of a permanent magnet and a coil), the rotating blades cut through the magnetic lines of force, periodically altering the magnetic flux of the coil and inducing an electrical pulse signal across the coil. This pulse signal is amplified and shaped by an amplifier to form a continuous rectangular pulse wave with a specific amplitude. This pulse wave is then transmitted to a controller to calculate the instantaneous or total flow rate of the liquid. Currently, flowmeter manufacturers calibrate the measurement parameters of flowmeters before shipment, allowing users to directly use the flowmeter to measure liquid flow. In practice, it has been found that when drones are used for crop protection operations, the spraying system and the type of pesticides sprayed can affect the sensitivity and accuracy of the flow meter, resulting in inaccurate measurement data and affecting the effectiveness of the crop protection operation. Therefore, the pulse coefficient of the flow meter needs to be calibrated before crop protection operations.

[0035] FIG1 is a flow chart of a flow meter pulse coefficient calibration method, which specifically includes:

[0036] S110, recording the initial pulse number N0 of the flow meter and the initial mass M0 of the medicine box before the plant protection UAV starts operation.

[0037] To save calibration time, the pulse coefficient of the flowmeter on the agricultural drone is determined, and static calibration is performed during ground-based agricultural trials before the drone's formal agricultural operations. Furthermore, to reduce calibration costs, the spray tank contains only water, which typically accounts for 30% of the tank's capacity.

[0038] During the plant protection test, staff put a known mass of clean water into the drone's medicine box and controlled the drone to spray on the spot. Before the drone operated, the flight controller obtained and recorded the initial pulse number N0 of the flow meter and the initial mass M0 of the medicine box.

[0039] S120, recording the number of pulses N of the flow meter and the mass M of the medicine box when the plant protection UAV stops operating.

[0040] After the plant protection UAV stops operating, the flight controller obtains and records the pulse number N of the flow meter and the mass M of the medicine box. The mass M of the medicine box can be directly obtained through a weighing device, such as a weighing sensor.

[0041] S130, determining the calibration pulse coefficient

[0042] The flight controller determines the calibration pulse coefficient k1 based on the recorded initial pulse number N0 before the plant protection UAV starts operating, the initial mass M0 of the medicine box, the pulse number N of the flow meter when the plant protection UAV stops operating, and the mass M of the medicine box. The calibration pulse coefficient k1 is the actual spraying amount expressed per unit pulse.

[0043] S140: Update the pulse coefficient of the flow meter using the calibrated pulse coefficient.

[0044] After completing the pulse coefficient calibration process, the flowmeter on the agricultural drone will provide real-time pulse count feedback to the flight controller during actual operation. The flight controller then uses the calibrated pulse coefficient and pulse count to determine the actual spray volume during operation: actual spray volume = calibrated pulse coefficient × pulse count. Simultaneously, the flight controller will provide real-time feedback of the calculated actual spray flow rate to the ground station or user terminal, allowing the display interface of the ground station or user terminal to synchronously display the spray flow rate reported by the flowmeter for the user to view.

[0045] The flowmeter pulse coefficient calibration method shown in Figure 1 uses clean water to calibrate the flowmeter's pulse coefficient before the plant protection drone officially operates. Because the amount of water used during the test is relatively small, the calibrated pulse coefficient is significantly affected by sensor error fluctuations. Furthermore, since the sprayed liquid is clean water, which differs in viscosity and fluidity from the actual sprayed liquid, the calibrated pulse coefficient will also vary, resulting in inaccurate measurement data during actual operation.

[0046] FIG2 is a flow chart of a method for calibrating a flow meter of a plant protection drone according to an embodiment of the present application.

[0047] S210, obtain the pulse number N of the flow meter before the plant protection UAV operation i And the mass M of the medicine box i ; Get the pulse number N of the flow meter after the plant protection drone is operating j And the mass M of the medicine box j .

[0048] In some possible embodiments, when the state of the plant protection drone changes from locked to unlocked, the pulse number of the flow meter and the mass M of the medicine box are obtained. i When the state of the plant protection drone changes from the unlocked state to the locked state, record the pulse number N of the flow meter j And the mass M of the medicine box j .

[0049] In certain possible embodiments, the flight controller determines whether the plant protection drone is locked or unlocked by obtaining the status of a lock indicator light. If the lock indicator light is on, the plant protection drone is currently locked; if the lock indicator light is off, the plant protection drone is currently unlocked. The lock indicator light status can be used to determine whether the plant protection drone is locked or unlocked, thereby recording the pulse count of the flow meter and the quality of the medicine box before and after the plant protection drone's operation. This can improve the automation level of the pulse coefficient calibration of the plant protection drone's flow meter and enhance calibration efficiency.

[0050] In some possible embodiments, the mass of the medicine box can be directly obtained by a weighing device, such as a weighing sensor, which is not specifically limited here.

[0051] S220, when M i -M j is greater than the first threshold and N j -N i If it is greater than the second threshold, execute S230; otherwise, end.

[0052] In some possible embodiments, the first threshold and the second threshold are preset calibration conditions, which can be manually set and adjusted. For example, the preset calibration condition is that the mass of the sprayed liquid is greater than 2 kg and the change in the number of pulses of the flowmeter is greater than 400. The embodiments of the present application do not specifically limit this. The error of the weighing sensor mainly comes from the sensitivity of the sensor. The sensitivity of the sensor refers to the minimum weight change it can detect. For objects with small mass, the weight change may be very small, which is lower than the sensitivity range of the sensor. Therefore, when there is a slight change in weight, the sensor may not be able to detect it accurately, resulting in an increase in error. Correspondingly, the measurement accuracy of the pulse flowmeter is limited. When the mass of the liquid medicine is too small, the number of pulses counted by the flowmeter may be less than the actual number of pulses, resulting in a large error. Therefore, the embodiment of the present application can only calibrate the pulse coefficient of the flowmeter when the mass change is greater than the first threshold and the change in the number of pulses is greater than the second threshold, which can effectively improve the calibration accuracy of the pulse coefficient of the flowmeter.

[0053] S230, determining and recording the pulse coefficient of the flow meter according to the mass change value of the medicine box and the pulse number change value of the flow meter.

[0054] The pulse coefficient of the current flow meter is calculated based on the mass change of the medicine box before and after the plant protection drone operation and the corresponding change in the number of pulses of the flow meter. The calculated pulse coefficient is saved for the flight controller to call and calibrate the pulse coefficient of the flow meter.

[0055] In some possible embodiments, the pulse coefficient of the flow meter is determined according to the mass change value of the medicine box and the pulse number change value of the flow meter, specifically:

[0056] The ratio of the mass change of the medicine box to the pulse number change of the flow meter is taken as the pulse coefficient of the flow meter, that is, the jth pulse coefficient The jth pulse coefficient is the mass of the liquid medicine represented by a unit pulse.

[0057] In some possible embodiments, the pulse coefficient of the flow meter is determined according to the mass change value of the medicine box and the pulse number change value of the flow meter, which can also be:

[0058] The ratio of the change in the number of pulses of the flow meter to the change in the mass of the medicine box is taken as the pulse coefficient of the flow meter, i.e. the jth pulse coefficient At this time, the jth pulse coefficient is the change in the number of pulses of the flow meter when a unit mass of liquid medicine is sprayed.

[0059] It should be understood that the above pulse count calculation method is only an example and should not constitute any limitation to this application.

[0060] S240, obtaining the j-th pulse coefficient and the n-times pulse coefficients before the j-th pulse coefficient, and determining whether the n+1 pulse coefficients are valid. If so, executing S250; otherwise, ending.

[0061] The flight controller obtains the jth pulse coefficient and the n pulse coefficients preceding the jth pulse coefficient, i.e., the jnth pulse coefficient to the jth pulse coefficient, to obtain n+1 pulse coefficients. It should be understood that these n+1 pulse coefficients are obtained from n+1 historical operations at different time points, and these n+1 historical operations were performed by the drone under different operating conditions.

[0062] In certain possible embodiments, the validity of the n+1 pulse coefficients can be determined by calculating the standard deviation of the n+1 pulse coefficients and determining whether the standard deviation is less than a certain standard deviation threshold, wherein the standard deviation threshold is a preset calibration condition that can be manually set and adjusted. If the standard deviation of the n+1 pulse coefficients is less than the preset standard deviation threshold, it means that the measurement results of the flow meter during the operation corresponding to the above pulse coefficient of the agricultural drone are relatively stable. In other words, the pulse coefficient calculated after the corresponding n+1 operations is relatively accurate and can be used to calculate the calibration pulse coefficient. Using the more accurate pulse coefficient calculated after multiple operations to calibrate the pulse coefficient of the flow meter can improve the calibration accuracy.

[0063] In some possible embodiments, if the standard deviation of the n+1 pulse coefficients is greater than or equal to a preset standard deviation threshold, the j-th pulse coefficient is not recorded and the calibration pulse coefficient is not updated.

[0064] It should be understood that the standard deviation in the above embodiment can also be common parameters describing the degree of data dispersion, such as variance and coefficient of variation. The above method of determining whether the n+1 pulse coefficient is valid is only an example and should not constitute any limitation to this application.

[0065] S250, determining a calibration pulse coefficient based on the n+1 pulse coefficients, and using the calibration pulse coefficient to update the pulse coefficient of the flow meter.

[0066] In some possible embodiments, the arithmetic mean of n+1 pulse coefficients is used as the calibration pulse coefficient, that is, Where k is the calibration pulse coefficient, k s is the sth pulse coefficient, jn≤s≤j.

[0067] In some possible embodiments, the weighted average of n+1 pulse coefficients is used as the calibration pulse coefficient, that is, Where k is the calibration pulse coefficient, t is the number of groups obtained by grouping n+1 pulse coefficients with the same pulse coefficients, and k is the calibration pulse coefficient. ris the pulse coefficient value of the rth group, f r is the pulse coefficient k r Frequency of occurrence.

[0068] When using multiple historical pulse coefficients to calculate the calibration pulse coefficient, adopting a weighted average method can further eliminate the influence of extreme values ​​on the calibration pulse coefficient and improve the accuracy of the calibration pulse coefficient.

[0069] It should be understood that the above-mentioned method of determining the calibration pulse coefficient based on n+1 pulse coefficients is merely an example and should not constitute any limitation to the present application.

[0070] The method for determining the calibration pulse coefficient of the flow meter of a plant protection drone provided in the embodiment of the present application can determine whether the flow meter meets the preset calibration conditions after each operation of the plant protection drone, and determine the calibration pulse coefficient of the flow meter based on multiple measurement results after meeting certain calibration conditions. It can effectively improve the accuracy of the calibration pulse coefficient when the plant protection drone replaces the liquid or the operating parts are aging, providing important support for the subsequent precise operation of the plant protection drone.

[0071] In some possible embodiments, when the plant protection UAV is operating, the flight controller obtains the pulse number and the updated pulse coefficient of the flow meter, and calculates the actual spraying amount of the plant protection UAV based on the above pulse number and pulse coefficient.

[0072] In some possible embodiments, the actual spraying amount = current pulse coefficient × pulse number, where the current pulse coefficient is obtained based on the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations to the pulse number change value of the flow meter.

[0073] In some possible embodiments, the actual spraying amount = the number of pulses ÷ the current pulse coefficient, where the current pulse coefficient is obtained based on the ratio of the change in the number of pulses of the flow meter of the plant protection drone during multiple operations to the change in the mass of the medicine box.

[0074] It can be seen that the formula used to calculate the actual spraying volume of the agricultural drone based on the number of pulses and the pulse coefficient needs to be determined according to the calculation method of the pulse coefficient. After the flight controller calculates the actual spraying volume of the agricultural drone, it will feed the calculated actual spraying volume back to the ground station or user end in real time. The display interface of the ground station or user end will synchronously display the sprayed liquid volume reported by the flow meter for the user to view, so that the user can better control the operation progress of the agricultural drone based on the real-time actual spraying volume.

[0075] In certain possible embodiments, the flight controller can also control the spraying system to accurately complete the spraying operation based on a preset spraying volume and an updated pulse coefficient. Specifically, for example, given the preset spraying volume and the current flow meter pulse coefficient, the target number of pulses required to spray the preset amount of liquid can be calculated. The flight controller then monitors the flow meter pulse count and stops the spraying operation when the target number of pulses is reached.

[0076] In some possible embodiments, the target pulse number = the preset spraying amount ÷ the current pulse coefficient, where the current pulse coefficient is obtained based on the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations to the pulse number change value of the flow meter.

[0077] In some possible embodiments, the target pulse number = preset spraying amount × current pulse coefficient, where the current pulse coefficient is obtained based on the ratio of the pulse number change value of the flow meter of the plant protection drone during multiple operations and the mass change value of the medicine box.

[0078] As can be seen, the formula used to calculate the target pulse number based on the preset spray volume and pulse coefficient needs to be determined based on how the pulse coefficient is calculated. After calculating the target pulse number, the flight controller feeds it back to the ground station or user terminal, so that the display interface of the ground station or user terminal displays the target number of pulses required to achieve the preset spray volume for the user to view. At the same time, the flight controller monitors the pulse count of the flow meter and stops the operation when the target pulse count is reached. This method can accurately control the operation duration of the agricultural drone and effectively improve the operation effect of the agricultural drone.

[0079] In certain possible embodiments, to more accurately observe the actual spraying conditions of the plant protection drone, the flight controller can also calculate the average flow rate of the flow meter over a certain period of time. The flight controller obtains a preset collection duration and, during the operation of the plant protection drone, records the third and fourth pulse counts corresponding to the flow meter at the first and second moments, respectively, where the interval between the first and second moments is the length of the collection duration. The flight controller then calculates the average flow rate of the flow meter based on the third and fourth pulse counts, the collection duration, and the pulse coefficient.

[0080] In some possible embodiments, the formula for calculating the average flow rate of the flow meter during the collection time is: average flow rate = (fourth pulse number - third pulse number) × pulse coefficient ÷ collection time, where the pulse coefficient is obtained based on the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations and the change value of the pulse number of the flow meter.

[0081] In some possible embodiments, the formula for calculating the average flow rate of the flow meter during the collection time is: average flow rate = (fourth pulse number - third pulse number) ÷ pulse coefficient ÷ collection time, where the pulse coefficient is obtained based on the ratio of the change in the number of pulses of the flow meter during multiple operations of the plant protection drone and the change in the mass of the medicine box.

[0082] The plant protection drone flow meter calibration method provided in the embodiment of the present application can effectively improve the accuracy of the calibration pulse coefficient by determining the calibration pulse coefficient of the flow meter based on multiple measurement results after meeting certain calibration conditions; the actual spraying amount of the plant protection drone and the target number of pulses required to complete the spraying of a certain amount of liquid medicine can be determined based on the calibration pulse coefficient, so that the user can perform precise control, thereby effectively improving the operation effect of the plant protection drone.

[0083] Figure 3 is a block diagram of a flow meter calibration device 300 for a plant protection drone according to an embodiment of the present application. This device can be used to calibrate flow meters on plant protection drones. The device can be implemented using software and / or hardware and can generally be integrated into plant protection drones. As shown in Figure 3, the flow meter calibration device includes an acquisition module 310, a calculation module 320, a control module 330, and a calibration module 340, wherein:

[0084] The acquisition module 310 is used to obtain the locking status of the plant protection drone, the number of pulses of the flow meter before and after the operation of the plant protection drone, and the mass of the medicine box; it is also used to obtain the current pulse coefficient and n historical pulse coefficients of the flow meter, the current pulse coefficient is the pulse coefficient currently being used by the flow meter, the historical pulse coefficient is the multiple historical pulse coefficients stored by the plant protection drone, and the current pulse coefficient and the historical pulse coefficient are the pulse coefficients determined by the plant protection drone flow meter calibration method provided by any embodiment of the present application; as well as parameters such as preset calibration condition parameters, preset spraying amount and preset collection time.

[0085] The calculation module 320 is used to calculate whether the change value of the medicine box mass and the change value of the flow meter pulse number before and after the operation of the plant protection UAV meet the calibration conditions. When the calibration conditions are met, the pulse coefficient of the flow meter is calculated based on the change value of the medicine box mass and the change value of the flow meter pulse number; it is used to determine whether the calibration conditions are met based on the current pulse coefficient and n historical pulse coefficients, and when the calibration conditions are met, the calibration pulse coefficient is calculated based on the current pulse coefficient and n historical pulse coefficients; it is used to calculate the actual spraying amount based on the pulse coefficient and the number of pulses of the flow meter; it is used to calculate the target number of pulses based on the preset spraying amount and pulse coefficient; it is also used to calculate the average flow rate of the flow meter within the collection time based on the pulse coefficient, the collection time and the number of pulses within the collection time.

[0086] In some possible embodiments, the formula for calculating the average flow rate of the flow meter during the collection time is: average flow rate = (fourth pulse number - third pulse number) × pulse coefficient ÷ collection time, where the pulse coefficient is obtained based on the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations and the change value of the pulse number of the flow meter.

[0087] In some possible embodiments, the formula for calculating the average flow rate of the flow meter during the collection time is: average flow rate = (fourth pulse number - third pulse number) ÷ pulse coefficient ÷ collection time, where the pulse coefficient is obtained based on the ratio of the change in the number of pulses of the flow meter during multiple operations of the plant protection drone and the change in the mass of the medicine box.

[0088] In some possible embodiments, the pulse coefficient of the flow meter is determined according to the mass change value of the medicine box and the pulse number change value of the flow meter, specifically:

[0089] The ratio of the mass change of the medicine box to the pulse number change of the flow meter is taken as the pulse coefficient of the flow meter, that is, the jth pulse coefficient The jth pulse coefficient is the mass of the liquid medicine represented by a unit pulse.

[0090] In some possible embodiments, the pulse coefficient of the flow meter is determined according to the mass change value of the medicine box and the pulse number change value of the flow meter, which can also be:

[0091] The ratio of the change in the number of pulses of the flow meter to the change in the mass of the medicine box is taken as the pulse coefficient of the flow meter, i.e. the jth pulse coefficient At this time, the jth pulse coefficient is the change in the number of pulses of the spraying unit mass flowmeter.

[0092] It should be understood that the above pulse count calculation method is only an example and should not constitute any limitation to this application.

[0093] In some possible embodiments, the arithmetic mean of n+1 pulse coefficients is used as the calibration pulse coefficient, that is, Where k is the calibration pulse coefficient, k s is the sth pulse coefficient, jn≤s≤j.

[0094] In some possible embodiments, the weighted average of n+1 pulse coefficients is used as the calibration pulse coefficient, that is, Where k is the calibration pulse coefficient, t is the number of groups obtained by grouping n+1 pulse coefficients with the same pulse coefficients, and k is the calibration pulse coefficient. r is the pulse coefficient value of the rth group, f r is the pulse coefficient k r Frequency of occurrence.

[0095] It should be understood that the above-mentioned method of determining and recording the calibration pulse coefficient based on n+1 pulse coefficients is merely an example and should not constitute any limitation to the present application.

[0096] In some possible embodiments, the actual spraying amount = current pulse coefficient × pulse number, where the current pulse coefficient is the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations to the pulse number change value of the flow meter.

[0097] In some possible embodiments, the actual spraying amount = the number of pulses ÷ the current pulse coefficient, where the current pulse coefficient is the ratio of the change in the number of pulses of the flow meter of the plant protection drone during multiple operations to the change in the mass of the medicine box.

[0098] In some possible embodiments, the target pulse number = the preset spraying amount ÷ the current pulse coefficient, where the current pulse coefficient is the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations to the pulse number change value of the flow meter.

[0099] In some possible embodiments, the target pulse number = preset spraying amount × current pulse coefficient, where the current pulse coefficient is the ratio of the pulse number change value of the flow meter of the plant protection drone during multiple operations to the mass change value of the medicine box.

[0100] In some possible embodiments, the formula for calculating the average flow rate of the flow meter during the collection time is: average flow rate = (fourth pulse number - third pulse number) × pulse coefficient ÷ collection time, wherein the third pulse number and the fourth pulse number are the pulse numbers corresponding to the flow meter at the first moment and the second moment respectively, the interval between the first moment and the second moment is the size of the collection time, and the pulse coefficient is the ratio of the mass change value of the medicine box of the plant protection drone during multiple operations to the change value of the pulse number of the flow meter.

[0101] In some possible embodiments, the formula for calculating the average flow rate of the flow meter during the collection time is: average flow rate = (fourth pulse number - third pulse number) ÷ pulse coefficient ÷ collection time, wherein the third pulse number and the fourth pulse number are the pulse numbers corresponding to the flow meter at the first moment and the second moment respectively, the interval between the first moment and the second moment is the size of the collection time, and the pulse coefficient is the ratio of the change in the number of pulses of the flow meter during multiple operations of the plant protection drone to the change in the mass of the medicine box.

[0102] The control module 330 is used to control the plant protection drone to perform the weighing operation of the medicine box according to the locking state of the plant protection drone; and is also used to control the operation of the spraying system according to the target pulse number.

[0103] The calibration module 340 is configured to update the pulse coefficient of the flow meter according to the calibration pulse coefficient obtained by the calculation module.

[0104] An embodiment of the present application further provides an electronic device, which includes a memory and a processor. The memory stores a program, and when the program is executed by the processor, the above-mentioned flow meter calibration method is implemented.

[0105] An embodiment of the present application further provides a storage medium for computer-readable storage, wherein the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the above-mentioned flow meter calibration method.

[0106] It will be understood by those skilled in the art that the technical solution of the present application, in essence, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, and such software can be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As is well known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer.

[0107] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for calibrating a flow meter for a plant protection drone, characterized in that: include: Obtain a first mass of the medicine box and a first pulse number of the flow meter before the plant protection UAV operates, and obtain a second mass of the medicine box and a second pulse number of the flow meter after the plant protection UAV operates; Determine that the change value of the medicine box mass is greater than a first threshold and the change value of the pulse number is greater than a second threshold; The first threshold refers to the minimum value of the medicine box mass change value set manually, and the second threshold refers to the minimum value of the pulse number change value set manually; The change value of the medicine box mass is the difference between the first mass and the second mass, the change value of the pulse number is the difference between the second pulse number and the first pulse number, and the pulse coefficient of the flow meter is calculated according to the change value of the medicine box mass and the change value of the pulse number; wherein the pulse coefficient calculation formula is: Pulse coefficient = change in medicine box mass ÷ change in pulse number; Obtaining n historical pulse coefficients, and determining a calibration pulse coefficient of the flow meter according to the pulse coefficient and a standard deviation of the n historical pulse coefficients, wherein the n historical pulse coefficients are respectively obtained in n historical operation processes at different time points, and the n historical operation processes are performed under different working conditions; the determining the calibration pulse coefficient of the flow meter includes: Determining that a standard deviation of the pulse coefficient and the n historical pulse coefficients is less than a third threshold, wherein the third threshold refers to a maximum value of a standard deviation of the pulse coefficient and the n historical pulse coefficients that is manually set; If the standard deviation of the pulse coefficient and the n historical pulse coefficients is less than a third threshold, then: Using the calibration pulse coefficient to update the pulse coefficient of the flow meter, wherein the calibration pulse coefficient is the arithmetic mean of the pulse coefficient and the n historical pulse coefficients; or, The calibration pulse coefficient is a weighted average of the pulse coefficient and the n historical pulse coefficients, wherein the weight of each pulse coefficient is the number of times each pulse coefficient appears; If the standard deviation of the pulse coefficient and the n historical pulse coefficients is greater than or equal to a third threshold, then: not recording the pulse coefficient, and not updating the calibration pulse coefficient; Get the preset collection duration; Obtaining a third pulse number corresponding to a first moment and a fourth pulse number corresponding to a second moment recorded when the plant protection UAV is operating, wherein the interval between the first moment and the second moment is the collection duration; The average flow rate within the acquisition time is determined according to the calibration pulse coefficient, the third pulse number and the fourth pulse number, wherein the calculation formula of the average flow rate is: average flow rate = (fourth pulse number - third pulse number) × calibration pulse coefficient ÷ acquisition time.

2. The method according to claim 1, characterized in that The method further comprises: The actual spraying amount is calculated according to the calibration pulse coefficient and the number of pulses of the flow meter. The calculation formula of the actual spraying amount is: actual spraying amount = calibration pulse coefficient × number of pulses.

3. The method according to claim 1, characterized in that The method further comprises: The target pulse number is calculated according to the preset spraying amount and the calibration pulse coefficient, and the calculation formula of the target pulse number is: target pulse number=preset spraying amount÷calibration pulse coefficient.

4. A flow meter calibration device for plant protection drones, characterized in that: include: The acquisition module is used to obtain the first mass of the medicine box and the first pulse number of the flow meter before the plant protection UAV operation. The plant protection UAV has a second mass and a second pulse number of a flow meter of the medicine box after the operation; and Used to obtain n historical pulse coefficients, a first threshold and a second threshold; wherein the first threshold refers to the minimum value of the manually set medicine box mass change value, the second threshold refers to the minimum value of the manually set pulse number change value, the n historical pulse coefficients are obtained respectively in n historical operation processes at different time points, and the n historical operation processes are performed under different working conditions; and, Used to obtain a third threshold, a preset collection duration, and a third pulse number corresponding to a first moment and a fourth pulse number corresponding to a second moment recorded when the plant protection UAV is operating, wherein the interval between the first moment and the second moment is the collection duration, and the third threshold refers to the maximum value of the artificially set pulse coefficient and the standard deviation of the n historical pulse coefficients; A calculation module, used to calculate the medicine box mass change value according to the first mass and the second mass, calculate the pulse number change value according to the first pulse number and the second pulse number, and determine that the medicine box mass change value is greater than the first threshold value and the pulse number change value is greater than the second threshold value, and calculate the pulse coefficient of the flow meter according to the medicine box mass change value and the pulse number change value; further used to determine the calibration pulse coefficient of the flow meter according to the pulse coefficient and the standard deviation of the n historical pulse coefficients; and further used to execute the method described in any one of claims 1 to 3; A control module, used for controlling the plant protection UAV to perform weighing operations before and after the operation to obtain the first mass and the second mass; A calibration module is used to update the pulse coefficient of the flow meter using the calibration pulse coefficient.

5. The device according to claim 4, characterized in that The calculation module is also used to determine the average flow rate within the acquisition time according to the calibration pulse coefficient, the third pulse number and the fourth pulse number, wherein the calculation formula of the average flow rate is: average flow rate = (fourth pulse number - third pulse number) × calibration pulse coefficient ÷ acquisition time.

6. A plant protection drone, characterized in that: Comprising the device as claimed in claim 4 or 5.

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