A dynamic measurement sensing system for the moisture content of forest combustibles

Abstract

The present invention relates to the technical field of moisture content measurement systems, and particularly relates to a dynamic measurement sensing system for the moisture content of forest combustibles, including a regional height measurement unit. The forest area to be measured for moisture content is denoted as the target area, and a drone is controlled to measure the ground height. There are multiple uniformly distributed height measurement points preset in the target area, and the height values of each height measurement point are analyzed and calculated; a contour construction unit constructs a three-dimensional contour model within the target area by using the Kriging method based on the ground height of each point on the flight trajectory of the drone and the height values of each height measurement point; a regional classification unit measures the vegetation height value during the flight of the drone and divides the target area into a surface combustible area and a crown combustible area; a dynamic measurement unit integrates the surface combustible areas based on the type of unit area to obtain a surface coverage area, and dynamically adjusts the installation position of the moisture content sensor within the surface coverage area.

Description

Technical Field

[0001] The present invention relates to the technical field of moisture content measurement systems, and particularly to a dynamic measurement sensing system for the moisture content of forest combustibles. Background Art

[0002] The dynamic measurement of the moisture content of forest combustibles is of great significance for forest fire prevention and ecological safety management. The lower the moisture content of forest combustibles, the higher the fire risk. By dynamically and continuously monitoring the moisture content of combustibles, the changing trend of forest fire hazards can be grasped in real time, high-risk areas can be warned in a timely manner, and a scientific basis can be provided for fire prevention and emergency decision-making. In addition, dynamic measurement can also optimize the combustible management strategy, such as guiding planned burning, thinning and cleaning, etc., reducing the probability of fire occurrence and the spread speed, thereby protecting forest resources and reducing ecological and economic losses.

[0003] In the prior art, fixed sensors are used to continuously monitor the moisture content of multiple surface combustibles in the forest management area. For example, a combustible moisture content measurement sensing system disclosed in Chinese Patent Publication No. CN115420760A can realize long-term unattended monitoring of the moisture content of combustibles. However, the existing moisture content sensors are generally evenly distributed in various parts of the forest management area to monitor the moisture content of the whole area. During the setting process, the influence of terrain is usually not considered. As the main measurement object of the dynamic measurement sensing system for moisture content, the moisture content of surface combustibles (such as dead leaves, humus, etc.) shows different characteristics of high and low, which leads to the inability of the conventionally set moisture content sensors to detect moisture content anomalies in a timely manner. Summary of the Invention

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

[0005] To achieve the above object, the present invention is realized through the following technical solutions:

[0006] The present invention provides a dynamic measurement sensing system for the moisture content of forest combustibles, including at least:

[0007] A regional height measurement unit, which designates the forest area to be measured for moisture content as the target area, controls the unmanned aerial vehicle to fly back and forth in the target area while measuring the ground height, and presets a plurality of evenly distributed height measurement points in the target area, and analyzes and calculates the height values of each height measurement point based on the ground height of each point on the flight trajectory of the unmanned aerial vehicle;

[0008] The contour construction unit constructs a three-dimensional contour model within the target area using Kriging method based on the ground height of each point on the flight trajectory of the UAV and the height values of each measurement point.

[0009] The area classification unit measures the vegetation height value during the flight of the UAV, evenly divides the target area into multiple unit areas, and divides the unit area into a surface combustible area and a crown combustible area based on the broken line of the vegetation height value corresponding to the flight trajectory within the unit area.

[0010] The dynamic measurement unit integrates the surface combustible areas based on the type of the 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 tilt ratio of the three-dimensional surface, and dynamically adjusts the installation position of the moisture content sensor based on the tilt ratio of the three-dimensional surface and the tangent slopes of multiple points on the three-dimensional surface.

[0011] Furthermore, the process of measuring the ground height is as follows:

[0012] Control the UAV to fly back and forth at a fixed height within the target area, construct a covering circle with the vertical projection point of the UAV as the center and a preset length value as the radius, record the area passed by the covering circle during the flight of the UAV as the survey area, and make the survey area completely cover the target area.

[0013] The UAV emits a continuous wave with linearly modulated frequency, and calculates the ground height in real time through the frequency difference between the echo and the transmitted signal, and obtains the acquisition time corresponding to the ground height.

[0014] Furthermore, the calculation process of the height value of the measurement point is as follows:

[0015] Construct a plane rectangular coordinate system corresponding to the two-dimensional map, and draw the flight trajectory of the UAV and multiple measurement points.

[0016] When the measurement point coincides with the flight trajectory, use the ground height of the corresponding point as the height value of the measurement point.

[0017] When the measurement point does not coincide with the flight trajectory, obtain the minimum distance between the measurement point and the flight trajectory. When the minimum distance is less than or equal to the preset distance threshold, use the ground height of the corresponding point as the height value of the measurement point.

[0018] When the measurement point does not coincide with the flight trajectory and the minimum distance between the measurement point and the flight trajectory is greater than the preset distance threshold, calculate the height value of the measurement point based on the flight trajectory around the measurement point.

[0019] Furthermore, construct multiple groups of straight line groups with the measurement point as the intersection point, and each straight line group consists of two mutually perpendicular straight lines.

[0020] Analyze the straight line groups:

[0021] Denote the intersection points between each straight line group and the flight trajectory as target intersection points. When the target intersection points on the same straight line are on both sides of the measurement height point, denote this straight line as a target straight line. When both of the two straight lines in a straight line group are target straight lines, denote this straight line group as a preferred straight line group;

[0022] Analyze the preferred straight line group:

[0023] Split the two target straight lines in the preferred straight line group into four target rays with the measurement height point as the demarcation point. The target rays have the measurement height point as the endpoint. Obtain the target intersection point closest to the measurement height point on each target ray and denote it as the preferred intersection point. Calculate the distances between the four preferred intersection points and the measurement height point and find their average value, which is denoted as the preferred recommended value. Denote the preferred straight line group corresponding to the smallest preferred recommended value as the target straight line group;

[0024] Conduct a function analysis on the two target straight lines within the target straight line group and calculate the height value of the measurement height point.

[0025] Furthermore, obtain the two target straight lines corresponding to the target straight line group and analyze each target straight line:

[0026] Obtain the two-dimensional coordinates of the two preferred intersection points on the target straight line. Combine the height values corresponding to the preferred intersection points to construct the three-dimensional coordinates corresponding to the preferred intersection points. Construct a straight line passing through the three-dimensional coordinates corresponding to the two preferred intersection points and denote it as the three-dimensional straight line. Obtain the straight line function corresponding to the three-dimensional straight line. Based on the straight line function, determine the height value corresponding to the measurement height point and denote it as the measured height value;

[0027] Respectively obtain the measured height values corresponding to the two target straight lines and find their average value, which is denoted as the height value of the measurement height point.

[0028] Furthermore, the process of measuring the vegetation height value is as follows:

[0029] Measure the second height during the flight of the unmanned aerial vehicle. The second height is the distance between the unmanned aerial vehicle and the ground vegetation. Based on the second height corresponding to any point on the flight trajectory, obtain the second height h and the ground height H corresponding to any point on the flight trajectory. Calculate the vegetation height value Δh through the formula Δh = H - h.

[0030] Furthermore, the process of dividing the unit area is as follows:

[0031] Obtain the line segments of the flight trajectory within different unit areas and denote them as target line segments. Each unit area corresponds to a target line segment;

[0032] Obtain the line graph of the change in vegetation height values corresponding to the target line segment. Presuppose a vegetation height threshold, and use the straight line corresponding to the vegetation height threshold to divide the line in the line graph of the change in vegetation height values. Denote the part of the line above the vegetation height threshold as the crown line, and denote the part of the line below the vegetation height threshold as the ground line;

[0033] Respectively obtain the projected lengths of the crown line and the ground line, and denote them as the crown ratio and the ground ratio , substitute them into the formula for calculation, where λ is the preset weight coefficient. When the result is greater than 0, denote the corresponding unit area as the crown combustible area; when the result is less than or equal to 0, divide the corresponding unit area into the ground combustible area.

[0034] Furthermore, the dynamic adjustment process of the installation position of the moisture content sensor is as follows:

[0035] Obtain the three-dimensional surface corresponding to the ground coverage area, obtain the area of the three-dimensional surface and denote it as the surface area, obtain the horizontal projected area of the three-dimensional surface and denote it as the water storage area, and calculate the ratio of the surface area to the water storage area to obtain the inclination ratio;

[0036] When the inclination ratio is equal to 1, use the center point of the three-dimensional surface as the installation position of the moisture content sensor;

[0037] When the inclination ratio is greater than 1, construct multiple linear arrays, and denote the vertical planes intersecting with the three-dimensional surface as the vertical analysis planes. Denote the intersection curve of the vertical analysis plane and the three-dimensional surface as the target curve, and analyze each target curve:

[0038] Draw the target curve, obtain the tangent slope of any point on the target curve, and collectively call the point where the tangent slope is equal to 0 and the two endpoints of the target curve the pending observation points;

[0039] Obtain the height values of the pending observation points on all target curves to construct a height distribution sequence, obtain the height values corresponding to the highest point and the lowest point of the three-dimensional surface and calculate the difference to obtain the height difference, and substitute it into the formula for calculation to obtain the ideal height value ;

[0040] Among them:

[0041] is the height value corresponding to the lowest point of the three-dimensional surface;

[0042] represents the height difference, represents the inclination ratio, and e is the natural constant;

[0043] Take the pending observation point with the height value closest to the ideal height value as the target observation point, and set a moisture content sensor at the target observation point.

[0044] A computer device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the above-mentioned system is implemented.

[0045] A computer-readable storage medium stores a computer program thereon. When the computer program is executed by a processor, the above-mentioned system is implemented.

[0046] The technical solution provided by the present invention has the following beneficial effects compared with the known prior art:

[0047] 1. By analyzing the height values corresponding to multiple positions around the height measurement point, the present invention estimates the height value of the height measurement point, and can determine the height value of the height measurement point through the height values directly obtained from multiple surrounding positions when the height value of the height measurement point cannot be specifically measured, which helps to improve the efficiency and accuracy of the UAV for contour mapping of the forestry area terrain; by dividing the target area, the target area can be divided into multiple unit areas for refined analysis to improve the resolution of dynamic moisture content identification, and further distinguish 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 moisture content measurement result output.

[0048] 2. The dynamic measurement unit in the present invention analyzes the terrain in different areas, especially the terrain in the surface combustible area, so as to adjust the setting position of the moisture content sensor, enabling the moisture content sensor to quickly capture the moisture content anomaly in the surface combustible area, fully considering the situation of moisture loss of combustibles in the surface combustible area due to gravity influence. Compared with the sensor setting method in the prior art, the moisture content measurement effect is more significant. Description of the Drawings

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0050] Figure 1 It is the overall module block diagram of the present invention. Detailed Embodiments

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] The present invention will be further described below in conjunction with embodiments.

[0053] Refer to Figure 1 , a dynamic measurement sensing system for the moisture content of forest combustibles, at least including:

[0054] The forestry area where the moisture content needs to be measured is denoted as the target area.

[0055] An area height measurement unit uses a drone equipped with a frequency modulated continuous wave radar to scan the terrain contour of the target area, where:

[0056] Control the drone to fly back and forth at a fixed height (the flight height is fixed relative to the sea level) within the target area. With the vertical projection point of the drone as the center and a preset length value as the radius, construct a covering circle. Denote the area passed by the covering circle during the flight of the drone as the survey area, and make the survey area completely cover the target area;

[0057] The drone emits a continuously wave with linearly modulated frequency, and calculates the height above the ground (i.e., the distance between the drone and the ground surface) in real time through the frequency difference between the echo and the transmitted signal. The calculation formula for the height above the ground H is , where C is the speed of light, k is the frequency modulation slope, is the frequency difference, and obtain the acquisition time corresponding to the height above the ground;

[0058] The frequency modulated continuous wave radar can penetrate surface coverings such as tree canopies and bushes, measure the actual distance between the drone and the ground, and the frequency modulated continuous wave radar has strong anti-interference ability and high resolution (up to centimeter level), which is suitable for complex terrains and dynamic height tracking.

[0059] There is a preset two-dimensional map within the target area. Draw the flight trajectory of the drone (usually a curve) and multiple evenly arranged height measurement points 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, obtain the height above the ground corresponding to each point on the flight trajectory of the drone;

[0060] Calculate the height values of each height measurement point. Taking one of the height measurement points as an example, the process of calculating its height value is as follows:

[0061] Construct a two-dimensional plane rectangular coordinate system corresponding to the two-dimensional map so that any point on the height measurement point position and the flight trajectory can be represented by two-dimensional coordinates. When the height measurement point position coincides with the flight trajectory, the height value of the height measurement point position is the ground height corresponding to the position;

[0062] When the height measurement point position does not coincide with the flight trajectory, obtain the minimum distance between the height measurement point position and the flight trajectory. When the minimum distance is less than or equal to the preset distance threshold, the ground height corresponding to the position is used as the height value of the height measurement point position;

[0063] When the height measurement point position does not coincide with the flight trajectory and the minimum distance between the height measurement point position and the flight trajectory is greater than the preset distance threshold, construct multiple groups of mutually perpendicular straight line groups with the height measurement point position as the intersection point. Each straight line group consists of two straight lines;

[0064] Analyze the straight line group:

[0065] Record the intersection point between each straight line group and the flight trajectory as the target intersection point. When the target intersection points on the same straight line are on both sides of the height measurement point position, record the straight line as the target straight line. When both straight lines in the straight line group are target straight lines, record the straight line group as the preferred straight line group;

[0066] Analyze the preferred straight line group:

[0067] Split the two target straight lines in the preferred straight line group into four target rays with the height measurement point position as the demarcation point. The target rays have the height measurement point position as the endpoint. Obtain the target intersection point closest to the height measurement point position on each target ray and record it as the preferred intersection point. Calculate the distances between the four preferred intersection points and the height measurement point position and find the average value, which is recorded as the preferred recommended value. Record the preferred straight line group corresponding to the smallest preferred recommended value as the target straight line group;

[0068] Obtain the two target straight lines corresponding to the target straight line group and analyze each target straight line:

[0069] Obtain the two-dimensional coordinates of the two preferred intersection points on the target straight line and record them as 、 , combined with the height value corresponding to the preferred intersection point Construct the three-dimensional coordinates corresponding to the preferred intersection point 、 , construct a straight line passing through the three-dimensional coordinates of the two preferred intersection points and record it as the three-dimensional straight line. Obtain the straight line function corresponding to the three-dimensional straight line and record it as , where a, b, and c are the coefficient values obtained by function solving. Based on the straight line function, determine the height value corresponding to the two-dimensional coordinates of the height measurement point position and record it as the measured height value;

[0070] Obtain the measured height values corresponding to two target lines respectively and calculate the average value, which is denoted as the height value of the measurement point position.

[0071] It should be noted that when using a drone for cruise altitude measurement in the prior art, since the altitude measurement area is generally very large and is affected by wind and other factors, the controllability of the flight trajectory is not high. Therefore, it is difficult to control the drone to pass through each measurement point position one by one for altitude measurement, and it is impossible to perform uniform altitude measurement within the target area. And to draw the terrain contour within the target area, uniform altitude data is required. The area altitude measurement unit in the present invention estimates the height value of the measurement point position by analyzing the height values corresponding to multiple positions around the measurement point position. Thus, when it is impossible to specifically measure the height value of the measurement point position, the height value of the measurement point position can be determined through the height values directly obtained at multiple surrounding positions, which helps to improve the efficiency and accuracy of the drone carrying a frequency modulated continuous wave radar for terrain contour mapping in the forestry area.

[0072] The contour construction unit obtains the two-dimensional coordinates corresponding to multiple measurement point positions, constructs three-dimensional coordinates in combination with the height values corresponding to each measurement point position, and constructs a three-dimensional contour model within the target area by using the Kriging method based on the three-dimensional coordinates of multiple measurement point positions and the three-dimensional coordinates corresponding to any point on the drone flight trajectory. The coordinates of any point on the surface of the three-dimensional contour model can be calculated by using the Kriging method.

[0073] It should be noted that the Kriging method is a regression algorithm for spatially modeling and predicting (interpolating) a random process / random field based on the covariance function. It is a typical geostatistical algorithm and is widely used in fields such as geographical science, environmental science, and atmospheric science. Its main principle is "a geostatistical process of weighted averaging known samples to estimate unknown points on a plane and making the mathematical expectation of the estimated value the same as the true value and the variance the smallest", which can be applied to the contour construction unit to estimate the three-dimensional coordinates of other positions based on multiple sample three-dimensional coordinates, and will not be elaborated here too much.

[0074] The area classification unit measures the second height during the drone cruise altitude measurement process by using the lidar carried by the drone. 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 and in combination with the three-dimensional contour model, the target area is divided into a surface combustible area and a crown combustible area, where:

[0075] Obtain the second height h corresponding to any point on the flight trajectory and the ground height H, and calculate the vegetation height value Δh through the formula Δh = H - h;

[0076] Evenly divide the target area into multiple unit areas, the side length of the unit area is a preset value, and obtain the line segments of the flight trajectory within different unit areas, which are denoted as target line segments. Each unit area corresponds to a target line segment;

[0077] Analyze the target line segments within each unit area:

[0078] Obtain a line graph showing the change in vegetation height values corresponding to the target line segments. In the line graph of vegetation height value changes, the independent variable causing the change in vegetation height value is the unilateral length of the target line segment, that is, the distance from any point on the target line segment to one end point of the target line segment (this end point is the specified unchanged end point) is taken as the abscissa, and the corresponding vegetation height value at this point is taken as the ordinate. There is a preset vegetation height threshold. The line in the line graph of vegetation height value changes is segmented by the straight line corresponding to the vegetation height threshold. The part of the line above the vegetation height threshold is denoted as the crown line, and the part of the line below the vegetation height threshold is denoted as the ground line;

[0079] Respectively obtain the projected lengths of the crown line and the ground line (on the horizontal axis corresponding to the unilateral length of the target line segment), denoted as the crown ratio and the ground ratio , and substitute them into the formula for calculation, where λ is a preset weight coefficient. In a specific embodiment, λ takes the value of 1.2. When the result is greater than 0, the corresponding unit area is denoted as the crown combustible area. When the result is less than or equal to 0, the corresponding unit area is divided into the ground combustible area.

[0080] It should be noted that by dividing the target area, the target area can be divided into multiple unit areas, which is convenient for refined analysis and improves the resolution of dynamic identification of moisture content. And further distinguish the unit areas as ground combustible areas and crown combustible areas according to the vegetation height within the unit areas, which helps to adjust the measurement method and strategy according to the combustible type during the measurement of combustible moisture content, realize the dynamic adjustment of the measurement method, and helps to improve the accuracy of the output of the moisture content measurement result.

[0081] The dynamic measurement unit includes multiple moisture sensors for monitoring the moisture content of forest combustibles such as surface dead leaves, herbaceous vegetation, humus, moss, and lichen (the moisture sensors include but are not limited to implanted resistance / capacitance sensors, and other contact moisture measurement instruments can also be used). Integrate the unit areas based on the type of unit area, and dynamically adjust the installation positions of the moisture sensors in combination with the three-dimensional contour model, where:

[0082] Obtain multiple ground combustible areas within the target area, merge adjacent ground combustible areas to form a ground coverage area, and thus obtain multiple non-adjacent ground coverage areas. The process of determining the installation positions of the moisture sensors within the ground coverage area is as follows:

[0083] 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;

[0084] 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.

[0085] 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;

[0086] 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:

[0087] 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;

[0088] 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.

[0089] 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.

[0090] Specifically, the topographic difference between highlands and lowlands will significantly affect the moisture content dynamics of forest surface fuels. Compared with low-lying areas, the moisture content of surface fuels (such as dead branches, leaves, and humus) in high places usually drops faster. The main reasons include:

[0091] The terrain slope in high places is relatively large. After precipitation, water quickly runs off, and direct sunlight and air flow are stronger, accelerating water evaporation. In contrast, low-lying areas are prone to water accumulation and have poor ventilation, with higher humidity and longer water retention time. The wind speed in high places is higher, air exchange is frequent, and moisture is easily carried away. Due to terrain obstruction in low-lying areas, a local high-humidity environment is formed, inhibiting drying. High slopes receive more solar radiation, and the surface temperature rises faster, directly accelerating the dehydration of fuels. In low-lying areas, the sunshine duration is short and the radiation intensity is low due to the shielding effect. This terrain-driven moisture content difference causes the high-slope area to reach the flammable threshold (such as a moisture content < 10%) earlier, becoming a priority early warning area for forest fire risks, and targeted monitoring and fuel management need to be strengthened.

[0092] The dynamic measurement unit in the present invention analyzes the terrain in different regions, especially the terrain within the surface combustible region, so as to adjust the setting position of the moisture content sensor, enabling the moisture content sensor to quickly capture the moisture content anomalies within the surface combustible region, fully considering the situation of moisture loss of fuels within the surface combustible region due to gravity. Compared with the sensor setting method in the prior art, the moisture content measurement effect is more remarkable.

[0093] A computer device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the above system is implemented.

[0094] A computer-readable storage medium stores a computer program thereon, and when the computer program is executed by a processor, the above system is implemented.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and 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, obtains the area of ​​the three-dimensional surface and records it as the surface area, obtains the horizontal projection area of ​​the three-dimensional surface and records it as the water storage area, and calculates the ratio of the surface area to the water storage area to obtain the inclination ratio; The installation position of the moisture content sensor is dynamically adjusted 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: 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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