Control method of unmanned aerial vehicle for spraying flame retardant

Abstract

The invention discloses a fire retardant spraying unmanned aerial vehicle control method, and belongs to the field of unmanned aerial vehicle fire extinguishing, and the method comprises the steps: obtaining a distance-thermal imaging image fusing the temperature and distance of a fire scene, and positioning the bottom of the fire scene based on DEM topographic data of a target fire extinguishing area; the height of the fire scene is calculated, a relation model of the height and the width of the fire scene is constructed and used for calculating the combustion diameter of the fire scene, and the coverage range of fire retardant spraying is determined; according to the height and the horizontal distance from the unmanned aerial vehicle to the bottom of the fire scene, the spraying pressure and the total spraying amount of the unmanned aerial vehicle for controlling the nozzle to spray the flame retardant are calculated; and calculating the reaction force of the flame retardant on the unmanned aerial vehicle in the spraying process, constructing an attitude correction equation of the unmanned aerial vehicle, and correcting the attitude of the unmanned aerial vehicle. The fire retardant spraying and unmanned aerial vehicle attitude high-precision control can be achieved, the fire retardant spraying precision and effectiveness are remarkably improved, and the fire retardant spraying device can be applied to various types of complex fire scenes such as forests, grasslands and cities.

Description

Technical Field

[0001] The invention relates to the field of unmanned aerial vehicle fire extinguishing, and in particular to a method for controlling an unmanned aerial vehicle for spraying flame retardants. Background Art

[0002] With the development of society and the advancement of science and technology, drones have begun to be used to extinguish fires in response to large-scale, long-distance fires. In particular, for fires in complex terrains such as alpine forests and grasslands, which are difficult for firefighters to extinguish, drones carrying flame retardants for high-altitude spraying have natural advantages in extinguishing fires. Drone firefighting extinguishes fires from the air, has high firefighting efficiency, and can deal with large-scale fires at multiple locations.

[0003] However, in response to complex fire situations, how to achieve precise control of the flame retardant spraying process and the drone cruising process is a technical difficulty in drone firefighting. In the prior art, in the process of using drones to spray flame retardants for firefighting, it is impossible to accurately identify and evaluate the fire scene, and it is impossible to control the spraying for different fire scenes, resulting in inaccurate spraying of the ignition point and inaccurate spraying amount. Excessive spraying wastes flame retardants and reduces the drone's firefighting ability. Too little spraying cannot achieve the firefighting effect. In addition, the reaction force during the spraying process will affect the drone's posture, resulting in large spray positioning errors during secondary spraying. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for controlling a UAV for spraying flame retardants, which utilizes high-precision identification of the fire scene and calculation and evaluation of fire scene parameters to achieve precise control and positioning of the flame retardant spraying and reduce the impact of the spraying process on the UAV posture.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: A method for controlling a drone for spraying flame retardant is provided, comprising: Step S1: The UAV obtains a distance-thermal imaging image that integrates the temperature and distance of the fire scene, calculates the positioning coordinates of the bottom of the fire scene based on the DEM terrain data of the target fire extinguishing area, and the direction angle and field angle of the laser ranging and infrared thermal imaging, and realizes the positioning of the fire scene; Step S2: Calculate the height of the fire scene and construct a relationship model between the height and width of the fire scene to calculate the burning diameter of the fire scene and determine the coverage of the flame retardant spraying; Step S3: construct a control model for spraying flame retardant according to the height and horizontal distance of the drone from the bottom of the fire scene, and calculate the injection pressure and total spraying volume of the nozzle controlled by the drone to spray flame retardant; Step S4: Based on the cruising altitude of the UAV, the height and horizontal distance of the UAV from the bottom of the fire scene are used to calculate the reaction force on the UAV during the spraying of the flame retardant, and the attitude correction equation of the UAV is constructed to correct the attitude of the UAV.

[0006] Further, step S1 includes: Step S11: retrieve the DEM terrain data of the target fire extinguishing area, and use the UAV to carry the flame retardant to reach the fire scene. Use the laser rangefinder and infrared thermal imager to obtain the distance-thermal imaging image that integrates the temperature and distance of the fire scene, and obtain the temperature data of each pixel in the distance-thermal imaging image. and distance data , Number the pixels; Step S12: Setting the fire scene temperature threshold , compare temperature data Fire temperature threshold The size of , then determine the pixel is the fire scene pixel, if , then determine the pixel are non-fire pixels; Step S13: Delete the non-fire scene pixels in the distance-thermal imaging image, retain the fire scene pixels, and obtain the distance data corresponding to each fire scene pixel ; Step S14: Using the current cruising point of the drone as the coordinate origin, establish a three-dimensional coordinate system based on the drone's cruising altitude. Get the coordinates of the terrain positioning point under the drone in the three-dimensional coordinate system ; Based on the coordinates of the current cruising point of the drone in the DEM terrain data , the coordinates As the basis for coordinate system transformation, is the elevation of the terrain location point; Step S15: Using the laser rangefinder and infrared thermal imager on the drone to measure the direction of the β and field of view α Calculate the coordinates of the terrain points at the bottom of the fire scene in the three-dimensional coordinate system ; ; in, is the distance data corresponding to the bottom fire pixel, is the horizontal azimuth of the laser rangefinder and infrared thermal imager in the three-dimensional coordinate system; Step S16: Using coordinates With coordinates Calculate the coordinates of the terrain points at the bottom of the fire scene within the DEM terrain data ; ; Step S17: Based on the coordinates in the DEM terrain data Locate the fire scene and provide feedback to the control center on the current ignition point.

[0007] Further, step S2 includes: Step S21: Calculate the height of the fire scene based on the relative height of the fire scene pixel at the top compared to the fire scene pixel at the bottom in the distance-thermal imaging image. H ; ; in, is the pixel coordinate of the top fire pixel, is the pixel coordinate of the bottom fire pixel, is the proportional coefficient between pixel coordinates and actual distance; Step S22: Using the height of the fire Calculate the burning diameter of the fire ; Step S23: The topographic point coordinates at the bottom of the fire scene As the center point of flame retardant spraying, the coverage radius of flame retardant is The coverage of the flame retardant spraying is generated with the center point of the flame retardant spraying as the center of the circle.

[0008] Furthermore, the combustion diameter R The calculation method is: ; in, is the burning rate of combustibles at the fire location, is the air density, g is the acceleration due to gravity, u is the wind speed around the fire scene, is the characteristic wind speed, , The combustion range.

[0009] Further, step S3 includes: Step S31: The drone controls the angle of the flame retardant spray nozzle to point to the terrain point at the bottom of the fire scene, and the drone controls the angle of the flame retardant spray nozzle to point to the terrain point at the bottom of the fire scene according to the height of the drone from the bottom of the fire scene. and horizontal distance , build a control model for flame retardant spraying , calculate the injection pressure of the drone controlled nozzle spraying flame retardant p ; Step S32: According to the rated spraying intensity of the nozzle , considering the attenuation of the spraying intensity within the coverage area of ​​the flame retardant spraying, calculate the total spraying amount Q .

[0010] Furthermore, the control model of flame retardant spraying for: ; in, is the injection pressure based on the vertical injection velocity component, is the injection pressure based on the lateral injection velocity component, is the density of the flame retardant, Indicates taking the maximum value, is the velocity coefficient of the injection velocity.

[0011] Furthermore, the total spraying volume is calculated Q The method is; ; in, is the spray intensity attenuation coefficient, is a natural constant, is the rated spray intensity.

[0012] Further, step S4 includes: Step S41: Based on the cruising altitude of the drone The drone controls the nozzle to point to the bottom of the fire and controls the amount of flame retardant sprayed. Q and injection pressure p , extinguish the fire; Step S42: Calculate the height of the drone from the bottom of the fire scene and horizontal distance Calculate the horizontal reaction force on the drone during flame retardant spraying and vertical reaction force ; ; in, is the mass flow rate of flame retardant during spraying; Step S43: Based on the horizontal reaction force and vertical reaction force Construct the attitude correction equation for the UAV during the flame retardant spraying process; ; in, Respectively around x , y , z The angular velocity of the axis, Respectively around x ,y , z The moment of inertia of the shaft, They are x , y , z The reaction force in the direction of , The resultant force is equal to the horizontal reaction force , and satisfies , It is the position coordinate of the reaction point on the UAV relative to the mass center of the UAV during the flame retardant spraying process; Step S44: During the process of the UAV spraying the flame retardant, the posture of the UAV is corrected according to the posture correction equation to ensure the accuracy of the flame retardant spraying process.

[0013] The beneficial effects of the present invention are as follows: the present solution uses infrared imaging technology and laser ranging technology to locate and identify the fire scene, calculate the height and burning diameter data of the fire scene, and is used to locate the spraying of flame retardants and determine the spraying range. While ensuring the fire extinguishing effect, it avoids excessive spraying of flame retardants, resulting in waste of flame retardants, and achieves accurate calculation of the amount and pressure of flame retardant spraying. At the same time, the calculated flame retardant spraying control data can be used for drone attitude correction to reduce the impact of the flame retardant spraying process on the drone attitude. The present invention can achieve high-precision control of flame retardant spraying and drone attitude, significantly improving the accuracy and effectiveness of flame retardant spraying, and can be applied to multiple types of complex fire scene applications such as forests, grasslands, and cities. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Flowchart of a method for controlling a UAV for spraying flame retardants.

[0015] Figure 2 Schematic diagram of the fire scene and drone space. DETAILED DESCRIPTION

[0016] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0017] like Figure 1 As shown, a method for controlling a UAV for spraying flame retardant includes: S1: The drone obtains a distance-thermal image that integrates the temperature and distance of the fire scene, based on the DEM terrain data of the target fire extinguishing area, as well as the direction angle of laser ranging and infrared thermal imaging.β and field of view α Calculate the positioning coordinates of the bottom of the fire scene to locate the bottom of the fire scene. Step S1 specifically includes: Step S11: retrieve the DEM terrain data of the target fire extinguishing area, and use the UAV to carry the flame retardant to reach the fire scene. Use the laser rangefinder and infrared thermal imager to obtain the distance-thermal imaging image that integrates the temperature and distance of the fire scene, and obtain the temperature data of each pixel in the distance-thermal imaging image. and distance data , Number the pixels; Temperature data Indicates the temperature of the burning object corresponding to each pixel in the distance-thermal imaging image, the distance data Indicates the straight-line distance from the burning object position to the drone for each pixel in the distance-thermal imaging image. During the fusion process of the fire scene temperature and distance, ensure that the measurement range of the laser rangefinder is the same as the imaging range of the infrared thermal imager, that is, the pixels of the laser distance image and the infrared temperature image correspond in position.

[0018] During the flight, the drone will feed back the positioning coordinates to the DEM terrain data in real time. The coordinates of the drone's flight positioning will be converted into the DEM terrain data space, and the fire scene data obtained by the drone will be used to locate the fire scene. The DEM terrain data can reflect the terrain elevation and plane coordinate data in the target fire extinguishing area.

[0019] Step S12: Setting the fire scene temperature threshold , compare temperature data Fire temperature threshold The size of , then determine the pixel n is the fire scene pixel, if , then determine the pixel are non-fire pixels; Step S13: Delete the non-fire scene pixels in the distance-thermal imaging image, retain the fire scene pixels, and obtain the distance data corresponding to each fire scene pixel d , distance data d Indicates the straight-line distance from different locations of the fire scene; Step S14: Using the current cruising point of the drone as the coordinate origin, establish a three-dimensional coordinate system, such as Figure 2 As shown, according to the cruising altitude of the drone Get the coordinates of the terrain positioning point under the drone in the three-dimensional coordinate system ; Based on the coordinates of the current cruising point of the drone in the DEM terrain data , the coordinates As the basis for coordinate system transformation, is the elevation of the terrain location point; In the coordinate conversion process of this embodiment, the unit coordinate scale of the three-dimensional coordinate system is the same as the unit coordinate scale in the DEM terrain data, and the directions of the coordinate axes are the same, which facilitates coordinate conversion between different coordinate systems and avoids positioning errors caused by differences between coordinate systems.

[0020] Step S15: Using the laser rangefinder and infrared thermal imager on the drone to measure the direction of the β and field of view α Calculate the coordinates of the terrain points at the bottom of the fire scene in the three-dimensional coordinate system ; ; in, is the distance data corresponding to the bottom fire pixel, is the horizontal azimuth of the laser rangefinder and infrared thermal imager in the three-dimensional coordinate system; Step S16: Using coordinates With coordinates Calculate the coordinates of the terrain points at the bottom of the fire scene within the DEM terrain data ; ; Step S17: Based on the coordinates in the DEM terrain data Locate the fire scene and provide feedback to the control center on the current ignition point.

[0021] Step S2: Calculate the height of the fire scene and construct a relationship model between the height and width of the fire scene to calculate the burning diameter of the fire scene and determine the coverage of the flame retardant spraying. Step S2 specifically includes: Step S21: Calculate the height of the fire scene based on the relative height of the fire scene pixel at the top compared to the fire scene pixel at the bottom in the distance-thermal imaging image. H ; ; in, is the pixel coordinate of the top fire pixel, is the pixel coordinate of the bottom fire pixel, is the proportional coefficient between pixel coordinates and actual distance.

[0022] When the present invention fuses the temperature data and distance data of pixels in the distance-thermal imaging image, since the upper part of the fire scene is the flame part and the laser can penetrate the flame, the distance data of the upper part of the pixels in the distance-thermal imaging image is an unreal distance value, while the lower part is the burning object or the burning area and the distance data is a real distance value. When calculating the height data of the fire scene, the calculation is based on the distance data of the bottom pixels.

[0023] Step S22: Using the height of the fire Calculate the burning diameter of the fire ; When calculating the burning diameter of the fire scene, this embodiment equates the burning effect of the fire scene to a standard experimental model, takes into account the influence of the wind field, ignores the influence of other natural conditions, and reduces the difficulty of calculation. It has been verified that the fire scene height and the burning width model of the combustion material used in this embodiment are sufficient to meet the requirements of flame retardant spraying evaluation, and the fire extinguishing effect of the drone spraying flame retardant meets the requirements.

[0024] ; in, is the burning rate of combustibles at the fire location, is the air density, g is the acceleration due to gravity, u is the wind speed around the fire scene, is the characteristic wind speed, , Combustion range, combustion range Determine based on the terrain where the fire occurs. If it occurs indoors, take the maximum straight-line distance in the indoor space as the burning range. If it occurs in mountainous areas, the straight-line distance between the fire location and the nearest obstacle is taken as the burning range. ; Step S23: The topographic point coordinates at the bottom of the fire scene As the center point of flame retardant spraying, the coverage radius of flame retardant is 2 R The coverage of the flame retardant spraying is generated with the center point of the flame retardant spraying as the center of the circle.

[0025] Step S3: According to the height and horizontal distance between the UAV and the bottom of the fire scene, a control model for the spraying of flame retardants is constructed to calculate the injection pressure and total spraying volume of the UAV controlled nozzle for spraying flame retardants. Step S3 specifically includes: Step S31: The drone controls the angle of the flame retardant spray nozzle to point to the terrain point at the bottom of the fire scene, and the drone controls the angle of the flame retardant spray nozzle to point to the terrain point at the bottom of the fire scene according to the height of the drone from the bottom of the fire scene. and horizontal distance , build a control model for flame retardant spraying , calculate the injection pressure of the drone controlled nozzle spraying flame retardant p ; ; in, is the injection pressure based on the vertical injection velocity component, is the injection pressure based on the lateral injection velocity component, is the density of the flame retardant, Indicates taking the maximum value, is the speed coefficient, the maximum speed coefficient is 0.97 and the general speed coefficient is 0.95; Step S32: According to the rated spraying intensity of the nozzle , considering the attenuation of the spraying intensity within the coverage area of ​​the flame retardant spraying, calculate the total spraying amount Q ; ; in, is the spray intensity attenuation coefficient, is a natural constant, is the rated spraying intensity. Since the nozzle is aimed at the center of the spraying coverage, this embodiment considers that there will be no spraying intensity attenuation in the center of the flame retardant spraying coverage during the calculation process. Based on this, the spraying intensity is Gaussian distributed, that is, the closer to the spraying center point, the higher the spraying intensity, and the farther the distance, the lower the spraying intensity. The spraying intensity represents the spraying amount per unit area per unit time.

[0026] Step S4: Based on the cruising altitude of the drone, and using the altitude and horizontal distance of the drone from the bottom of the fire scene, calculate the reaction force on the drone during the spraying of the flame retardant, construct the attitude correction equation of the drone, and correct the flight attitude of the drone. Step S4 specifically includes: Step S41: Based on the cruising altitude of the drone The drone controls the nozzle to point to the bottom of the fire and controls the amount of flame retardant sprayed. Q and injection pressure p , extinguish the fire; Step S42: Calculate the height of the drone from the bottom of the fire scene and horizontal distance Calculate the horizontal reaction force on the drone during flame retardant spraying and vertical reaction force ; ; in, is the mass flow rate of flame retardant during spraying; Step S43: Based on the horizontal reaction force and vertical reaction force Construct the attitude correction equation for the UAV during the flame retardant spraying process; ; in, Respectively around x , y , z The angular velocity of the axis, Respectively aroundx , y , z The moment of inertia of the shaft, They are x , y , z The reaction force in the direction of , The resultant force is equal to the horizontal reaction force , and satisfies , It is the position coordinate of the reaction point on the UAV relative to the mass center of the UAV during the flame retardant spraying process; Step S44: During the process of the UAV spraying the flame retardant, the flight attitude of the UAV is corrected according to the attitude correction equation to ensure the accuracy of the flame retardant spraying process.

[0027] The present invention uses infrared imaging technology and laser ranging technology to locate and identify the fire scene, calculate the height and burning diameter data of the fire scene, and is used to locate the spraying of flame retardants and determine the spraying range. While ensuring the fire extinguishing effect, it avoids excessive spraying of flame retardants, resulting in waste of flame retardants, and realizes accurate calculation of the amount and pressure of flame retardant spraying. At the same time, the calculated flame retardant spraying control data can be used for drone attitude correction to reduce the impact of the flame retardant spraying process on the drone attitude. The present invention can achieve high-precision control of flame retardant spraying and drone attitude, significantly improve the accuracy and effectiveness of flame retardant spraying, and can be applied to multiple types of complex fire scene applications such as forests, grasslands, and cities.

Claims

1. A method for controlling a drone for spraying flame retardants, characterized in that: include: Step S1: The UAV obtains a distance-thermal imaging image that integrates the temperature and distance of the fire scene, calculates the positioning coordinates of the bottom of the fire scene based on the DEM terrain data of the target fire extinguishing area, and the direction angle and field angle of the laser ranging and infrared thermal imaging, and realizes the positioning of the fire scene; Step S2: Calculate the height of the fire scene and construct a relationship model between the height and width of the fire scene to calculate the burning diameter of the fire scene and determine the coverage of the flame retardant spraying; Step S3: construct a control model for spraying flame retardant according to the height and horizontal distance of the drone from the bottom of the fire scene, and calculate the injection pressure and total spraying volume of the nozzle controlled by the drone to spray flame retardant; Step S4: Based on the cruising altitude of the UAV, the height and horizontal distance of the UAV from the bottom of the fire scene are used to calculate the reaction force on the UAV during the spraying of the flame retardant, and the attitude correction equation of the UAV is constructed to correct the attitude of the UAV.

2. The method for controlling a UAV for spraying flame retardant according to claim 1, characterized in that: The step S1 comprises: Step S11: retrieve the DEM terrain data of the target fire extinguishing area, and use the UAV to carry the flame retardant to reach the fire scene. Use the laser rangefinder and infrared thermal imager to obtain the distance-thermal imaging image that integrates the temperature and distance of the fire scene, and obtain the temperature data of each pixel in the distance-thermal imaging image. and distance data , Number the pixels; Step S12: Setting the fire scene temperature threshold , compare temperature data Fire temperature threshold The size of , then determine the pixel is the fire scene pixel, if , then determine the pixel are non-fire pixels; Step S13: Delete the non-fire scene pixels in the distance-thermal imaging image, retain the fire scene pixels, and obtain the distance data corresponding to each fire scene pixel ; Step S14: Using the current cruising point of the drone as the coordinate origin, establish a three-dimensional coordinate system based on the drone's cruising altitude. Get the coordinates of the terrain positioning point under the drone in the three-dimensional coordinate system ; Based on the coordinates of the current cruising point of the drone in the DEM terrain data , the coordinates As the basis for coordinate system transformation, is the elevation of the terrain location point; Step S15: Using the laser rangefinder and infrared thermal imager on the drone to measure the direction of the β and field of view α Calculate the coordinates of the terrain points at the bottom of the fire scene in the three-dimensional coordinate system ; ； in, is the distance data corresponding to the bottom fire pixel, is the horizontal azimuth of the laser rangefinder and infrared thermal imager in the three-dimensional coordinate system; Step S16: Using coordinates With coordinates Calculate the coordinates of the terrain points at the bottom of the fire scene within the DEM terrain data ; ； Step S17: Based on the coordinates in the DEM terrain data Locate the fire scene and provide feedback to the control center on the current ignition point.

3. The method for controlling a UAV for spraying flame retardant according to claim 2, characterized in that: The step S2 comprises: Step S21: Calculate the height of the fire scene based on the relative height of the fire scene pixel at the top compared to the fire scene pixel at the bottom in the distance-thermal imaging image. H ; ； in, is the pixel coordinate of the top fire pixel, is the pixel coordinate of the bottom fire pixel, is the proportional coefficient between pixel coordinates and actual distance; Step S22: Using the height of the fire Calculate the burning diameter of the fire ; Step S23: The topographic point coordinates at the bottom of the fire scene As the center point of flame retardant spraying, the coverage radius of flame retardant is The coverage of the flame retardant spraying is generated with the center point of the flame retardant spraying as the center of the circle.

4. The method for controlling a UAV for spraying flame retardant according to claim 3, characterized in that: The burning diameter R The calculation method is: ； in, is the burning rate of combustibles at the fire location, is the air density, g is the acceleration due to gravity, u is the wind speed around the fire scene, is the characteristic wind speed, , The combustion range.

5. The method for controlling a UAV for spraying flame retardant according to claim 3, characterized in that: The step S3 comprises: Step S31: The drone controls the angle of the flame retardant spray nozzle to point to the terrain point at the bottom of the fire scene, and the drone controls the angle of the flame retardant spray nozzle to point to the terrain point at the bottom of the fire scene according to the height of the drone from the bottom of the fire scene. and horizontal distance , build a control model for flame retardant spraying , calculate the injection pressure of the drone controlled nozzle spraying flame retardant p ; Step S32: According to the rated spraying intensity of the nozzle , considering the attenuation of the spraying intensity within the coverage area of ​​the flame retardant spraying, calculate the total spraying amount Q .

6. The method for controlling a UAV for spraying flame retardant according to claim 5, characterized in that: The control model of the flame retardant spraying for: ； in, is the injection pressure based on the vertical injection velocity component, is the injection pressure based on the lateral injection velocity component, is the density of the flame retardant, Indicates taking the maximum value, is the velocity coefficient of the injection velocity.

7. The method for controlling a UAV for spraying flame retardant according to claim 5, characterized in that: The total spraying volume is calculated Q The method is; ； in, is the spray intensity attenuation coefficient, is a natural constant, is the rated spray intensity.

8. The method for controlling a UAV for spraying flame retardant according to claim 5, characterized in that: The step S4 comprises: Step S41: Based on the cruising altitude of the drone The drone controls the nozzle to point to the bottom of the fire and controls the amount of flame retardant sprayed. Q and injection pressure p , extinguish the fire; Step S42: Calculate the height of the drone from the bottom of the fire scene and horizontal distance Calculate the horizontal reaction force on the drone during flame retardant spraying and vertical reaction force ; ； in, is the mass flow rate of flame retardant during spraying; Step S43: Based on the horizontal reaction force and vertical reaction force Construct the attitude correction equation for the UAV during the flame retardant spraying process; ； in, Respectively around x , y , z The angular velocity of the axis, Respectively around x , y , z The moment of inertia of the shaft, They are x , y , z The reaction force in the direction of , The resultant force is equal to the horizontal reaction force , and satisfies , It is the position coordinate of the reaction point on the UAV relative to the mass center of the UAV during the flame retardant spraying process; Step S44: During the process of the UAV spraying the flame retardant, the posture of the UAV is corrected according to the posture correction equation to ensure the accuracy of the flame retardant spraying process.

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