Dynamic measurement sensing system for moisture content of forestry combustible

Abstract

The invention relates to the technical field of water content measurement systems, in particular to a forestry combustible water content dynamic measurement sensing system, which comprises an area height measurement unit for marking a forestry area needing water content measurement as a target area, controlling an unmanned aerial vehicle to measure the height to the ground and presetting a plurality of height measurement positions uniformly distributed in the target area, analyzing and calculating the height value of each height measurement position; the contour construction unit is used for constructing a three-dimensional contour model in the target area by adopting a Kriging method based on the ground height of each point on the flight path of the unmanned aerial vehicle and the height value of each height measurement point; the region classification unit is used for measuring a vegetation height value in the flight process of the unmanned aerial vehicle and dividing a target region into a ground surface combustible region and a crown combustible region; and the dynamic measurement unit is used for integrating the ground surface combustible areas based on the type of the unit area to obtain a ground surface coverage area and dynamically adjusting the mounting position of a water content sensor in the ground surface coverage area.

Description

Technical Field

[0001] The invention relates to the technical field of moisture content measurement systems, and in particular to a dynamic measurement sensor system for moisture content of forestry combustibles. Background Art

[0002] Dynamic measurement of the moisture content of forestry combustibles is of great significance for forestry fire prevention and ecological safety management. The lower the moisture content of forestry combustibles, the higher the fire risk. By dynamically and continuously monitoring the moisture content of combustibles, we can grasp the changing trend of forestry fire hazards in real time, timely warn high-risk areas, and provide a scientific basis for fire prevention and emergency decision-making. In addition, dynamic measurement can also optimize combustible management strategies, such as guiding planned burning, thinning and clearing, reducing the probability and spread of fires, thereby protecting forestry resources and reducing ecological and economic losses.

[0003] In the prior art, fixed sensors are used to continuously monitor the moisture content of surface combustibles at multiple locations within a forestry management area. For example, a combustible moisture content measurement sensor system disclosed in China Publication No. CN115420760A can achieve long-term unattended monitoring of the moisture content of combustibles. However, existing moisture content sensors are generally evenly distributed and set in various locations within the forestry management area to monitor the moisture content of the entire area. The influence of terrain is usually not taken into account during the location setting process. As the main measurement object of the moisture content dynamic measurement sensor system, the moisture content of surface combustibles (such as dead branches and leaves, humus, etc.) presents different characteristics. This results in the inability of conventionally set moisture content sensors to detect moisture content anomalies in a timely manner. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a forestry combustible moisture content dynamic measurement sensing system, which can effectively solve the problem in the prior art that the position of the moisture content sensor cannot be dynamically adjusted based on the terrain.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides a forestry combustible moisture content dynamic measurement sensing system, which at least comprises: The regional height measurement unit records the forest area where moisture content measurement is required as the target area, controls the UAV to fly back and forth in the target area while measuring the height above the ground. There are multiple height measurement points evenly distributed in the target area. The height value of each height measurement point is calculated based on the height above the ground of each point on the flight trajectory of the UAV. The contour construction unit uses the Kriging method to construct a three-dimensional contour model within the target area based on the ground height of each point on the flight trajectory of the UAV and the height value of each height measurement point; Regional classification unit: measure the vegetation height value during the UAV flight process, divide the target area evenly into multiple unit areas, and divide the unit area into surface combustible area and crown combustible area based on the vegetation height value change line corresponding to the UAV flight track in the unit area; The dynamic measurement unit integrates the surface combustible area based on the type of unit area to obtain the surface coverage area, obtains the three-dimensional surface corresponding to the surface coverage area based on the three-dimensional contour model, analyzes the inclination ratio of the three-dimensional surface, and dynamically adjusts the installation position of the moisture content sensor based on the inclination ratio of the three-dimensional surface and the tangent slopes of multiple points on the three-dimensional surface.

[0006] Furthermore, the process of measuring the height above the ground is as follows: Control the drone to fly back and forth at a fixed altitude in the target area, build a coverage circle with the vertical projection point of the drone as the center and the preset length as the radius, and record the area passed by the coverage circle during the flight of the drone as the surveying area, so that the surveying area completely covers the target area; The UAV transmits a continuous wave with linear frequency modulation, calculates the altitude above the ground in real time through the frequency difference between the echo and the transmitted signal, and obtains the acquisition time corresponding to the altitude above the ground.

[0007] Furthermore, the height value calculation process of the height measurement point is as follows: Construct a plane rectangular coordinate system corresponding to the two-dimensional map, and draw the flight trajectory of the drone and multiple height measurement points; When the altitude measurement point coincides with the flight trajectory, the height above the ground of the corresponding point is used as the altitude value of the altitude measurement point; When the height measurement point does not coincide with the flight trajectory, the minimum distance between the height measurement point and the flight trajectory is obtained. When the minimum distance is less than or equal to the preset distance threshold, the height above the ground of the corresponding point is used as the height value of the height measurement point. When the altimeter point does not coincide with the flight trajectory, and the minimum distance between the altimeter point and the flight trajectory is greater than a preset distance threshold, the altitude value of the altimeter point is calculated based on the flight trajectory around the altimeter point.

[0008] Furthermore, multiple straight line groups are constructed with the height measurement points as intersection points, and each straight line group consists of two straight lines perpendicular to each other; Analyze the straight line group: The intersection point between each straight line group and the flight trajectory is recorded as the target intersection point. When the target intersection points on the same straight line are located on both sides of the height measurement point, the straight line is recorded as the target straight line. When the two straight lines in the straight line group are both target straight lines, the straight line group is recorded as the preferred straight line group. Analyze the selected straight line group: The two target lines in the preferred line group are split into four target rays with the altimetry point as the dividing point. The target rays take the altimetry point as the endpoint. The target intersection point closest to the altimetry point on each target ray is obtained as the preferred intersection point. The distances between the four preferred intersection points and the altimetry point are calculated and the average value is recorded as the preferred recommended value. The preferred line group corresponding to the smallest preferred recommended value is recorded as the target line group. Perform function analysis on the two target lines in the target line group and calculate the height value of the height measurement point.

[0009] Furthermore, two target lines corresponding to the target line group are obtained, and each target line is analyzed: Obtain the two-dimensional coordinates corresponding to the two preferred intersection points on the target straight line, construct the three-dimensional coordinates corresponding to the preferred intersection points in combination with the height values ​​corresponding to the preferred intersection points, construct a straight line passing through the three-dimensional coordinates corresponding to the two preferred intersection points as a three-dimensional straight line, obtain the straight line function corresponding to the three-dimensional straight line, determine the height value corresponding to the height measurement point based on the straight line function, and record it as a measured height value; Get the measured height values ​​corresponding to the two target straight lines respectively and calculate the average value, which is recorded as the height value of the height measuring point.

[0010] Furthermore, the vegetation height value measurement process is as follows: The second height is measured during the flight of the UAV. The second height is the distance between the UAV and the ground vegetation. Based on the second height corresponding to any point on the flight trajectory, the second height h and the height above the ground H corresponding to any point on the flight trajectory are obtained, and the vegetation height value Δh is calculated by the formula Δh=Hh.

[0011] Furthermore, the unit area division process is as follows: The line segments of the flight trajectory in different unit areas are recorded as target line segments, and each unit area corresponds to a target line segment; Obtain a polyline graph of vegetation height value changes corresponding to a target line segment, preset a vegetation height threshold, and segment the polyline in the polyline graph of vegetation height value changes with a straight line corresponding to the vegetation height threshold, record the polyline portion above the vegetation height threshold as a crown polyline, and record the polyline portion below the vegetation height threshold as a surface polyline; The projection lengths of the crown line and the ground line are obtained respectively and recorded as the crown proportion and land surface area , substitute into the formula The calculation is performed in , where λ is the preset weight coefficient. When the result is greater than 0, the corresponding unit area is recorded as the crown combustible area. When the result is less than or equal to 0, the corresponding unit area is divided into the surface combustible area.

[0012] Furthermore, the process of dynamic adjustment of the installation position of the moisture content sensor is as follows: Obtain a three-dimensional surface corresponding to the surface coverage area, obtain the area of ​​the three-dimensional surface and record it as the surface area, obtain the horizontal projection area of ​​the three-dimensional surface and record it as the water storage area, and calculate the ratio of the surface area to the water storage area to obtain the inclination ratio; When the tilt ratio is equal to 1, the center point of the three-dimensional surface is used as the installation position of the moisture content sensor; When the tilt ratio is greater than 1, multiple linear arrays are constructed and the vertical surfaces intersecting the three-dimensional surface are recorded as vertical analysis surfaces. The intersection curve of the vertical analysis surface and the three-dimensional surface is recorded as the target curve. Analysis is performed on each target curve: Draw the target curve, obtain the tangent slope of any point on the target curve, and refer to the points where the tangent slope is equal to 0 and the two end points of the target curve as pending observation points; Get the height values ​​of all the undetermined observation points on the target curve to build a height distribution series, get the height values ​​corresponding to the highest and lowest points of the three-dimensional surface and calculate the difference to get the height difference, substitute it into the formula Calculate the ideal height value ; in: is the height value corresponding to the lowest point of the three-dimensional surface; Indicates the height difference, represents the tilt ratio, e is a natural constant; The undetermined observation point whose height value is closest to the ideal height value is taken as the target observation point, and a moisture content sensor is set at the target observation point.

[0013] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the above system when executing the computer program.

[0014] A computer-readable storage medium stores a computer program, which implements the above system when executed by a processor.

[0015] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects: 1. The present invention estimates the height value of the altimetry point by analyzing the height values ​​corresponding to multiple positions around the altimetry point. When the height value of the altimetry point cannot be specifically measured, the height value of the altimetry point can be determined by the height values ​​that can be directly obtained from multiple surrounding positions, which helps to improve the efficiency and accuracy of contour mapping of forestry area terrain by UAVs; by dividing the target area, the target area can be divided into multiple unit areas for detailed analysis, improving the resolution of dynamic identification of moisture content, and further distinguishing the unit area into a surface combustible area and a crown combustible area according to the vegetation height in the unit area, which helps to improve the accuracy of the output of moisture content measurement results.

[0016] 2. The dynamic measurement unit in the present invention analyzes the terrain in different areas, especially the terrain in the surface combustible area, and adjusts the setting position of the moisture content sensor, so that the moisture content sensor can quickly capture the moisture content anomaly in the surface combustible area, and fully considers the loss of moisture in the combustible material in the surface combustible area due to gravity. Compared with the sensor setting method in the prior art, the moisture content measurement effect is more significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is the overall module block diagram of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention will be further described below in conjunction with the embodiments.

[0021] See also Figure 1 , a forestry fuel moisture content dynamic measurement sensor system, comprising at least: The forestry areas where moisture content measurement is required are recorded as target areas.

[0022] The regional height measurement unit uses a UAV equipped with a frequency modulated continuous wave radar to scan the terrain contour of the target area, including: Control the drone to fly back and forth at a fixed altitude (the flight altitude is fixed relative to the sea level) in the target area, and construct a coverage circle with the vertical projection point of the drone as the center and the preset length as the radius. The area covered by the coverage circle during the flight of the drone is recorded as the surveying area, so that the surveying area completely covers the target area; The drone transmits a frequency-linearly modulated continuous wave, and calculates the ground height (i.e., the distance between the drone and the ground) in real time through the frequency difference between the echo and the transmitted signal. The ground height H is calculated using the following formula: , where C is the speed of light, k is the frequency modulation slope, is the frequency difference, and the acquisition time corresponding to the height above the ground is obtained; Frequency modulated continuous wave radar can penetrate surface cover, such as tree canopies and bushes, to measure the actual distance between the drone and the ground. Frequency modulated continuous wave radar has strong anti-interference ability and high resolution (up to centimeter level), making it suitable for complex terrain and dynamic altitude tracking.

[0023] A two-dimensional map of the target area is preset, and the flight trajectory of the drone (usually a curve) and multiple evenly set height measurement points are drawn in the two-dimensional map. Any point on the flight trajectory of the drone corresponds to a moment. Based on the height above the ground and the trajectory position corresponding to the same moment, the height above the ground corresponding to each point on the flight trajectory of the drone is obtained; The height value of each height measurement point is calculated. Taking one of the height measurement points as an example, the height value calculation process is as follows: Construct a plane rectangular coordinate system corresponding to the two-dimensional map so that the altimetry point and any point on the flight trajectory can be represented by two-dimensional coordinates. When the altimetry point coincides with the flight trajectory, the height of the corresponding point above the ground is used as the height value of the altimetry point. When the height measurement point does not coincide with the flight trajectory, the minimum distance between the height measurement point and the flight trajectory is obtained. When the minimum distance is less than or equal to the preset distance threshold, the height above the ground of the corresponding point is used as the height value of the height measurement point. When the altimetry point does not coincide with the flight trajectory, and the minimum distance between the altimetry point and the flight trajectory is greater than the preset distance threshold, multiple groups of mutually perpendicular straight lines are constructed with the altimetry point as the intersection point, and each straight line group consists of two straight lines; Analyze the straight line group: The intersection point between each straight line group and the flight trajectory is recorded as the target intersection point. When the target intersection points on the same straight line are located on both sides of the height measurement point, the straight line is recorded as the target straight line. When the two straight lines in the straight line group are both target straight lines, the straight line group is recorded as the preferred straight line group. Analyze the selected straight line group: The two target lines in the preferred line group are split into four target rays with the altimetry point as the dividing point. The target rays take the altimetry point as the endpoint. The target intersection point closest to the altimetry point on each target ray is obtained as the preferred intersection point. The distances between the four preferred intersection points and the altimetry point are calculated and the average value is recorded as the preferred recommended value. The preferred line group corresponding to the smallest preferred recommended value is recorded as the target line group. Get the two target lines corresponding to the target line group and analyze each target line: Get the two-dimensional coordinates corresponding to the two optimal intersection points on the target line , , combined with the height value corresponding to the preferred intersection Construct the three-dimensional coordinates corresponding to the optimal intersection point , , construct a straight line passing through the three-dimensional coordinates corresponding to the two preferred intersection points, record it as a three-dimensional straight line, and obtain the straight line function corresponding to the three-dimensional straight line, record it as , where a, b, and c are coefficient values ​​obtained by solving the function, and the two-dimensional coordinates of the height measurement point are determined based on the straight line function The corresponding height value is recorded as the measured height value; Get the measured height values ​​corresponding to the two target straight lines respectively and calculate the average value, which is recorded as the height value of the height measuring point.

[0024] It should be noted that in the prior art, when drones are used for patrol altitude measurement, the altitude measurement area is generally very wide and will be affected by wind and other factors, resulting in a low controllability of the flight trajectory. Therefore, it is difficult to control the drone to pass through each altitude measurement point one by one for altitude measurement, and it is impossible to perform uniform altitude measurement in the target area. In order to draw the terrain contour in the target area, uniform altitude data is required. The regional altitude measurement unit in the present invention estimates the altitude value of the altitude measurement point by analyzing the altitude values ​​corresponding to multiple positions around the altitude measurement point. When the altitude value of the altitude measurement point cannot be specifically measured, the altitude value of the altitude measurement point can be determined by the altitude values ​​that can be directly obtained from multiple surrounding positions. This helps to improve the efficiency and accuracy of contour mapping of forestry area terrain by drones equipped with frequency-modulated continuous wave radars.

[0025] The contour construction unit obtains the two-dimensional coordinates corresponding to multiple height measuring points, and constructs three-dimensional coordinates based on the height values ​​corresponding to each height measuring point. Based on the three-dimensional coordinates of multiple height measuring points and the three-dimensional coordinates corresponding to any point on the flight trajectory of the UAV, the Kriging method is used to construct a three-dimensional contour model within the target area. The coordinates of any point on the surface of the three-dimensional contour model can be calculated using the Kriging method.

[0026] It should be noted that the Kriging method is a regression algorithm for spatial modeling and prediction (interpolation) of random processes / random fields based on the covariance function. It is a typical geostatistical algorithm and is widely used in geographical science, environmental science, atmospheric science and other fields. Its main principle is "a geostatistical process that uses weighted averaging of known samples to estimate unknown points on a plane, and makes the estimated value the same as the true value in mathematical expectation and with the minimum variance". It can be applied to estimating the three-dimensional coordinates of other locations in contour construction units based on multiple sample three-dimensional coordinates. I will not go into details here.

[0027] The regional classification unit uses the laser radar carried by the drone to measure the second height during the drone's patrol height measurement process. The second height is the distance between the drone and the ground vegetation. Based on the second height corresponding to any point on the flight trajectory, combined with the three-dimensional contour model, the target area is divided into the surface combustible area and the crown combustible area, where: Obtain the second height h and the ground height H corresponding to any point on the flight trajectory, and calculate the vegetation height value Δh by the formula Δh=Hh; The target area is evenly divided into multiple unit areas, the side length of the unit area is a preset value, and the line segments of the flight trajectory in different unit areas are recorded as target line segments, and each unit area corresponds to a target line segment; Analyze the target line segment in each unit area: Obtain a polyline graph of vegetation height value changes corresponding to the target segment. The dependent variable causing the vegetation height value change in the polyline graph is the unilateral length of the target segment, that is, the distance from any point on the target segment to the endpoint on one side of the target segment (the endpoint is the endpoint on the side that is specified to remain unchanged) is the horizontal coordinate, and the vegetation height value corresponding to the point is the vertical coordinate. A vegetation height threshold is preset, and the polyline in the polyline graph of vegetation height value changes is segmented by the straight line corresponding to the vegetation height threshold. The polyline portion above the vegetation height threshold is recorded as the crown polyline, and the polyline portion below the vegetation height threshold is recorded as the surface polyline. The projection lengths of the crown polyline and the ground polyline (on the horizontal axis corresponding to the length of the target line segment on one side) are obtained respectively and recorded as the crown proportion. and land surface area , substitute into the formula The calculation is performed in , where λ is a preset weight coefficient. In a specific embodiment, λ is 1.2. When the result is greater than 0, the corresponding unit area is recorded as a crown combustible area. When the result is less than or equal to 0, the corresponding unit area is divided into a surface combustible area.

[0028] It should be noted that by dividing the target area, the target area can be divided into multiple unit areas to facilitate detailed analysis and improve the resolution of dynamic identification of moisture content. The unit area can be further divided into surface combustible areas and crown combustible areas according to the vegetation height in the unit area. This helps to adjust the measurement method and strategy according to the type of combustible material during the measurement of moisture content of combustible materials, realize dynamic adjustment of the measurement method, and help improve the accuracy of the output of moisture content measurement results.

[0029] The dynamic measurement unit includes multiple moisture sensors for monitoring forestry combustibles such as dead branches and leaves, herbaceous vegetation, humus, moss and lichens on the ground (moisture sensors include but are not limited to implantable resistor / capacitor sensors, and other contact moisture measuring instruments can also be used). The unit areas are integrated based on the type of unit area, and the installation position of the moisture sensors is dynamically adjusted in combination with the three-dimensional contour model, among which: Acquire multiple surface combustible areas in the target area, merge adjacent surface combustible areas into a surface coverage area, and thereby obtain multiple non-adjacent surface coverage areas. The process of determining the installation position of the moisture content sensor in the surface coverage area is as follows: Obtain a three-dimensional surface corresponding to the surface coverage area, obtain the area of ​​the three-dimensional surface and record it as the surface area, obtain the horizontal projection area of ​​the three-dimensional surface and record it as the water storage area, and calculate the ratio of the surface area to the water storage area to obtain the inclination ratio; It should be noted that the inclination ratio is used to evaluate the regional slope of the floor coverage area. When the inclination ratio is larger, it means that the terrain in the surface coverage area is steeper and the difference in high and low potential is more obvious. The moisture content of the surface combustibles at high places decreases faster, resulting in uneven moisture content of the floor combustibles in the entire area. When the tilt ratio is equal to 1, the center point of the three-dimensional surface is used as the installation position of the moisture content sensor; When the tilt ratio is greater than 1, multiple vertical planes of linear arrays are constructed and recorded as vertical analysis planes. Multiple vertical analysis planes intersect with the three-dimensional surface. The intersection curve of the vertical analysis plane and the three-dimensional surface is recorded as the target curve. Analysis is performed on each target curve: Draw a target curve in a plane rectangular coordinate system, where the vertical height of the target curve is the vertical axis, obtain the tangent slope of any point on the target curve, and refer to the points where the tangent slope is equal to 0 and the two end points of the target curve as pending observation points, each of which corresponds to a height value; Get the height values ​​of all the undetermined observation points on the target curve to build a height distribution series, get the height values ​​corresponding to the highest and lowest points of the three-dimensional surface and calculate the difference to get the height difference, substitute it into the formula Calculate the ideal height value ,in is the height value corresponding to the lowest point of the three-dimensional surface, Indicates the height difference, represents the tilt ratio, e is a natural constant, the undetermined observation point whose height value is closest to the ideal height value is taken as the target observation point, and a moisture content sensor is set at the target observation point.

[0030] It should be noted that the fixed moisture content sensors in the prior art are usually arranged in a uniformly distributed manner at various locations within the target area, so as to perform large-scale detection of the moisture content of forestry combustibles in each target area. However, this uniformly distributed arrangement does not take into account the impact of terrain characteristics on the moisture content of forestry combustibles, especially the impact of high and low potential differences on the moisture content of forestry surface combustibles. This causes the moisture content of forestry combustibles to drift, affecting a series of subsequent steps.

[0031] Specifically, the topographic difference between highlands and lowlands significantly affects the moisture content dynamics of forest surface fuels. Compared with low-lying areas, the moisture content of surface fuels (such as dead branches and leaves, humus, etc.) located at high altitudes usually decreases faster. The main reasons include: The slope of the high terrain is larger, and water is lost quickly after precipitation. In addition, direct sunlight and air flow are stronger, which accelerates water evaporation. Low-lying areas are prone to water accumulation and poor ventilation, with high humidity and long water retention time. The wind speed is higher in high places, air exchange is frequent, and moisture is easily carried away. In low-lying areas, due to terrain shielding, a local high-humidity environment is formed, which inhibits drying. High slopes receive more solar radiation, and the surface temperature rises faster, which directly accelerates the dehydration of combustibles. Low-lying areas have short sunshine hours and low radiation intensity due to the shielding effect. This terrain-driven difference in moisture content causes high-slope areas to reach the flammable threshold earlier (such as moisture content <10%), becoming a priority warning area for forest fire risks, and targeted monitoring and combustible management need to be strengthened.

[0032] The dynamic measurement unit in the present invention analyzes the terrain in different areas, especially the terrain in the surface combustible area, and adjusts the setting position of the moisture content sensor, so that the moisture content sensor can quickly capture the moisture content anomaly in the surface combustible area, and fully considers the loss of moisture in the combustible material in the surface combustible area due to gravity. Compared with the sensor setting method in the prior art, the moisture content measurement effect is more significant.

[0033] A computer device includes a memory and a processor. The memory stores a computer program. The processor implements the above system when executing the computer program.

[0034] A computer-readable storage medium stores a computer program, which implements the above system when executed by a processor.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic measurement sensor system for moisture content of forestry combustibles, characterized in that: include: The regional height measurement unit records the forest area where moisture content measurement is required as the target area, controls the UAV to fly back and forth in the target area while measuring the height above the ground. There are multiple height measurement points evenly distributed in the target area. The height value of each height measurement point is calculated based on the height above the ground of each point on the flight trajectory of the UAV. The contour construction unit uses the Kriging method to construct a three-dimensional contour model within the target area based on the ground height of each point on the flight trajectory of the UAV and the height value of each height measurement point; Regional classification unit: measure the vegetation height value during the UAV flight process, divide the target area evenly into multiple unit areas, and divide the unit area into surface combustible area and crown combustible area based on the vegetation height value change line corresponding to the UAV flight track in the unit area; The dynamic measurement unit integrates the surface combustible area based on the type of unit area to obtain the surface coverage area, obtains the three-dimensional surface corresponding to the surface coverage area based on the three-dimensional contour model, analyzes the inclination ratio of the three-dimensional surface, and dynamically adjusts the installation position of the moisture content sensor based on the inclination ratio of the three-dimensional surface and the tangent slopes of multiple points on the three-dimensional surface.

2. A forestry combustible moisture content dynamic measurement sensor system according to claim 1, characterized in that: The process of measuring the height above the ground is as follows: Control the drone to fly back and forth at a fixed altitude in the target area, build a coverage circle with the vertical projection point of the drone as the center and the preset length as the radius, and record the area passed by the coverage circle during the flight of the drone as the surveying area, so that the surveying area completely covers the target area; The UAV transmits a continuous wave with linear frequency modulation, calculates the altitude above the ground in real time through the frequency difference between the echo and the transmitted signal, and obtains the acquisition time corresponding to the altitude above the ground.

3. A forestry combustible moisture content dynamic measurement sensor system according to claim 1, characterized in that: The calculation process of the height value of the height measuring point is as follows: Construct a plane rectangular coordinate system corresponding to the two-dimensional map, and draw the flight trajectory of the drone and multiple height measurement points; When the height measurement point coincides with the flight trajectory, the height above the ground of the corresponding point is used as the height value of the height measurement point; When the height measurement point does not coincide with the flight trajectory, the minimum distance between the height measurement point and the flight trajectory is obtained. When the minimum distance is less than or equal to the preset distance threshold, the height above the ground of the corresponding point is used as the height value of the height measurement point. When the altimeter point does not coincide with the flight trajectory, and the minimum distance between the altimeter point and the flight trajectory is greater than a preset distance threshold, the altitude value of the altimeter point is calculated based on the flight trajectory around the altimeter point.

4. A forestry combustible moisture content dynamic measurement sensor system according to claim 3, characterized in that: Construct multiple straight line groups with the height measurement points as intersection points, each straight line group consists of two mutually perpendicular straight lines; Analyze the straight line group: The intersection point between each straight line group and the flight trajectory is recorded as the target intersection point. When the target intersection points on the same straight line are located on both sides of the height measurement point, the straight line is recorded as the target straight line. When the two straight lines in the straight line group are both target straight lines, the straight line group is recorded as the preferred straight line group. Analyze the selected straight line group: The two target lines in the preferred line group are split into four target rays with the altimetry point as the dividing point. The target rays take the altimetry point as the endpoint. The target intersection point closest to the altimetry point on each target ray is obtained as the preferred intersection point. The distances between the four preferred intersection points and the altimetry point are calculated and the average value is recorded as the preferred recommended value. The preferred line group corresponding to the smallest preferred recommended value is recorded as the target line group. Perform function analysis on the two target lines in the target line group and calculate the height value of the height measurement point.

5. A forestry combustible moisture content dynamic measurement sensor system according to claim 4, characterized in that: Get the two target lines corresponding to the target line group and analyze each target line: Obtain the two-dimensional coordinates corresponding to the two preferred intersection points on the target straight line, construct the three-dimensional coordinates corresponding to the preferred intersection points in combination with the height values ​​corresponding to the preferred intersection points, construct a straight line passing through the three-dimensional coordinates corresponding to the two preferred intersection points as a three-dimensional straight line, obtain the straight line function corresponding to the three-dimensional straight line, determine the height value corresponding to the height measurement point based on the straight line function, and record it as a measured height value; Get the measured height values ​​corresponding to the two target straight lines respectively and calculate the average value, which is recorded as the height value of the height measuring point.

6. A forestry combustible moisture content dynamic measurement sensor system according to claim 1, characterized in that: The vegetation height measurement process is as follows: The second height is measured during the flight of the UAV. The second height is the distance between the UAV and the ground vegetation. Based on the second height corresponding to any point on the flight trajectory, the second height and the height above the ground corresponding to any point on the flight trajectory are obtained, and the difference between the second height and the height above the ground is calculated to obtain the vegetation height value.

7. The forestry combustible moisture content dynamic measurement sensor system according to claim 1 is characterized in that: The unit area division process is as follows: The line segments of the flight trajectory in different unit areas are recorded as target line segments, and each unit area corresponds to a target line segment; Obtain a polyline graph of vegetation height value changes corresponding to a target line segment, preset a vegetation height threshold, and segment the polyline in the polyline graph of vegetation height value changes with a straight line corresponding to the vegetation height threshold, record the polyline portion above the vegetation height threshold as a crown polyline, and record the polyline portion below the vegetation height threshold as a surface polyline; The projection lengths of the crown line and the ground line are obtained respectively and recorded as the crown proportion and land surface area , substitute into the formula The calculation is performed in , where λ is the preset weight coefficient. When the result is greater than 0, the corresponding unit area is recorded as the crown combustible area. When the result is less than or equal to 0, the corresponding unit area is divided into the surface combustible area.

8. The forestry combustible moisture content dynamic measurement sensor system according to claim 1 is characterized in that: The process of dynamic adjustment of the moisture content sensor installation position is as follows: Obtain a three-dimensional surface corresponding to the surface coverage area, obtain the area of ​​the three-dimensional surface and record it as the surface area, obtain the horizontal projection area of ​​the three-dimensional surface and record it as the water storage area, and calculate the ratio of the surface area to the water storage area to obtain the inclination ratio; When the tilt ratio is equal to 1, the center point of the three-dimensional surface is used as the installation position of the moisture content sensor; When the tilt ratio is greater than 1, multiple linear arrays are constructed and the vertical surfaces intersecting the three-dimensional surface are recorded as vertical analysis surfaces. The intersection curve of the vertical analysis surface and the three-dimensional surface is recorded as the target curve. Analysis is performed on each target curve: Draw the target curve, obtain the tangent slope of any point on the target curve, and refer to the points where the tangent slope is equal to 0 and the two end points of the target curve as pending observation points; Get the height values ​​of all the undetermined observation points on the target curve to build a height distribution series, get the height values ​​corresponding to the highest and lowest points of the three-dimensional surface and calculate the difference to get the height difference, substitute it into the formula Calculate the ideal height value ; in: is the height value corresponding to the lowest point of the three-dimensional surface; Indicates the height difference, represents the tilt ratio, e is a natural constant; The undetermined observation point whose height value is closest to the ideal height value is taken as the target observation point, and a moisture content sensor is set at the target observation point.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the system according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the system according to any one of claims 1 to 8 is implemented.

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