Forest falling object deposition thickness detection method and system

Abstract

The invention discloses a forest falling object siltation thickness detection method and system, belongs to the technical field of thickness detection, and aims to solve the technical problem of how to improve the accuracy of forest falling object siltation thickness detection and provide important parameters for forest fire danger prevention and fire rescue. According to the technical scheme, the method comprises the steps that an ultrasonic sensor is placed on the surface of a fallen object through the ultrasonic technology, and the actual thickness of the fallen object is accurately obtained through a temperature compensation method according to the fact that the signal strength and speed of ultrasonic waves propagating in the fallen object and soil are different; wherein the ultrasonic sensor is connected with the MCU, and the time difference of transmitting and receiving ultrasonic pulses in a medium is calculated by utilizing an accurate timer of the MCU.

Description

Technical Field

[0001] The present invention relates to the technical field of thickness detection, in particular to a method and system for detecting the thickness of forest fallen matter deposits. Background Art

[0002] The thickness of forest litter deposits can significantly increase the fire risk level by increasing the amount of combustible material and changing the humidity and ventilation conditions of the microenvironment. Therefore, the thickness of litter deposits is also an important parameter for forest fire prevention or fire rescue, as follows:

[0003] ① Scientific management of fallen debris accumulation is an important measure to reduce forest fire risk, but this must be balanced with ecological protection needs. Fire risk assessments require a comprehensive analysis of local vegetation types, climate conditions, and fallen debris characteristics.

[0004] ②Forest debris is the direct fuel source for forest fires. The thicker the accumulation of debris, the more combustible materials accumulate on the surface. When a fire occurs, there is more material available for combustion, and the fire may be more intense.

[0005] ③ Thick layers of fallen debris will hinder the evaporation of soil moisture, but at the same time may also form a loose and porous structure, promote air circulation (similar to the "chimney effect"), and accelerate the drying of combustible materials; after the winter snow melts, the thick layer of fallen debris may delay the wetting of the lower layer, prolong the drying time, and increase the risk of fire in spring and summer.

[0006] The thickness of dead litter deposits is positively correlated with fire intensity. Thick layers of combustible material will lead to longer burning times and higher flame heights. Loose, dry litter (such as pine needles in coniferous forests) may accelerate the spread of fire, while tightly packed fallen leaves may burn more slowly due to lack of oxygen, but will prolong the smoldering time.

[0007] In summary, existing technologies have problems such as the inability to detect or inaccurate detection of the thickness of forest debris accumulation, which can easily cause forest fires, or cause fires to develop rapidly and be difficult to extinguish.

[0008] Therefore, how to improve the accuracy of forest debris accumulation thickness detection and provide important parameters for forest fire prevention and fire rescue is a technical problem that needs to be solved urgently. Summary of the Invention

[0009] The technical task of the present invention is to provide a method and system for detecting the thickness of forest fallen debris, so as to solve the problem of how to improve the accuracy of forest fallen debris accumulation thickness detection and provide important parameters for forest fire risk prevention and fire rescue.

[0010] The technical task of the present invention is achieved in the following manner: a method for detecting the thickness of forest fallen debris accumulation, which utilizes ultrasonic technology. An ultrasonic sensor is placed on the surface of the fallen debris, and the actual thickness of the fallen debris is accurately obtained through temperature compensation method by taking advantage of the difference in signal strength and speed of ultrasonic waves propagating in the fallen debris and soil.

[0011] Among them, the ultrasonic sensor is connected to the MCU, and the MCU's precise timer (microsecond level) is used to calculate the time difference between the transmission and reception of the ultrasonic pulse in the medium.

[0012] Preferably, the MCU generates ultrasonic pulses to the ultrasonic sensor at regular intervals. Through the time difference between emission and reception, the MCU accurately calculates the emission and reception time of the ultrasonic pulses, and uses the MCU's precise timer to calculate the propagation time of the ultrasonic pulses in the medium.

[0013] More preferably, the actual thickness of the dropped object is accurately obtained by temperature compensation method as follows:

[0014] When the temperature rises, the elastic modulus decreases and the speed of sound decreases. The temperature correction formula for the elastic modulus is as follows:

[0015] E(T)=E0[1-β(T-T0)];

[0016] Where E(T) represents the temperature-corrected elastic modulus at the current temperature T; E0 represents the elastic modulus at the reference temperature T0; T represents the current temperature; β represents the temperature coefficient of the elastic modulus;

[0017] According to the temperature correction values ​​of elastic modulus and density, the sound velocity correction formula is as follows:

[0018]

[0019] Where c(T) represents the temperature-modified speed of sound at the current temperature T; ρ represents the density of the propagation medium;

[0020] The final thickness d is calculated as:

[0021] Where t represents the time from ultrasonic emission to reception.

[0022] More preferably, when the temperature change of the propagation medium is ignored, the sound speed correction formula is as follows:

[0023]

[0024] Where C0 is the speed of sound at the reference temperature.

[0025] More preferably, the temperature coefficient β of the elastic modulus is 0.01-0.03 / °C.

[0026] A system for detecting the thickness of forest fallen objects includes an MCU and an ultrasonic sensor. The ultrasonic sensor is connected to the MCU and placed on the surface of the fallen objects. The MCU obtains the time difference between the emission and reception of ultrasonic pulses in the medium, and then uses the different signal strengths and speeds of ultrasonic waves propagating in the fallen objects and soil to accurately obtain the actual thickness of the fallen objects through temperature compensation.

[0027] Preferably, a timer (microsecond level) is deployed in the MCU. The MCU generates ultrasonic pulses to the ultrasonic sensor at regular intervals. The timer accurately calculates the emission and reception time of the ultrasonic pulse through the time difference between emission and reception. The MCU's precise timer is used to calculate the propagation time of the ultrasonic pulse in the medium.

[0028] More preferably, the actual thickness of the dropped object is accurately obtained by temperature compensation method as follows:

[0029] The temperature correction formula for the elastic modulus is as follows:

[0030] E(T)=E0[1-β(T-T0)];

[0031] Where E(T) represents the temperature-corrected elastic modulus at the current temperature T; E0 represents the elastic modulus at the reference temperature T0; T represents the current temperature; β represents the temperature coefficient of the elastic modulus;

[0032] According to the temperature correction values ​​of elastic modulus and density, the sound velocity correction formula is as follows:

[0033]

[0034] Where c(T) represents the temperature-modified speed of sound at the current temperature T; ρ represents the density of the propagation medium;

[0035] The final thickness d is calculated as:

[0036] Where t represents the time from ultrasonic emission to reception.

[0037] The forest litter accumulation thickness detection method and system of the present invention have the following advantages:

[0038] (1) This invention utilizes ultrasonic technology, placing a probe on the surface of fallen objects. The different signal strengths and velocities of ultrasonic waves propagating through fallen objects and soil are exploited, along with temperature compensation and other compensation methods, to accurately calculate the actual thickness of fallen objects. The ultrasonic device is manually operated or carried by a robot to periodically measure the thickness of fallen objects in various areas, serving as an important parameter for forest fire prevention and fire rescue.

[0039] (2) The present invention solves the current problems of the inability to detect or inaccurate detection of forest litter thickness, and provides an accurate litter thickness parameter for forest fire risk monitoring, thereby assisting in forest fire risk prevention and fire rescue.

[0040] (3) The MCU of the present invention can calculate the thickness of fallen debris. For example, the device can be held by a forest ranger or installed on a robot dog. According to the set route and points, the thickness of the fallen debris at each point is collected in real time. By recording the time and point, a statistical chart of the forest debris thickness can be generated on the background software, providing assistance for later forest fire prevention and fire rescue.

[0041] (4) Data on forest debris accumulation thickness can significantly improve prevention accuracy (e.g., targeted cleanup, dynamic early warning) and rescue efficiency (e.g., fire behavior prediction, tactical optimization). The key lies in combining ecological principles with engineering technology to balance fire prevention and control with forest health and achieve sustainable management, as follows:

[0042] ① Predict the fire risk level by regularly monitoring the thickness of fallen debris and combining it with meteorological data (such as temperature, humidity, and wind speed);

[0043] ② Use data to promptly clear fallen objects in key areas to a safe depth, blocking the path of fire spread;

[0044] ③ Thick layers of forest debris can form fast-spreading "fire escape" channels, and rescue teams need to predict the direction of the fire in advance;

[0045] ④ When the thickness of forest debris is high, it is easy to cause underground fires (such as smoldering peat layers), and excavation equipment must be deployed instead of just water to extinguish the fire;

[0046] ⑤ Adjust the width of the isolation zone according to the thickness of forest litter accumulation;

[0047] ⑥ During rescue, the thickness of forest debris accumulation can be used to avoid having rescuers cross steep slopes or canyons with thick layers of combustible materials to prevent "fire tornadoes" or explosions. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will be further described below with reference to the accompanying drawings.

[0049] Attachment Figure 1 Schematic diagram of the forest litter accumulation thickness detection system. DETAILED DESCRIPTION

[0050] The forest litter accumulation thickness detection method and system of the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1:

[0052] This embodiment provides a method for detecting the thickness of forest fallen debris. This method uses ultrasonic technology. An ultrasonic sensor is placed on the surface of the fallen debris. The difference in signal strength and speed between the fallen debris and the soil is exploited to accurately determine the actual thickness of the fallen debris through temperature compensation.

[0053] Among them, the ultrasonic sensor is connected to the MCU, and the MCU's precise timer (microsecond level) is used to calculate the time difference between the transmission and reception of the ultrasonic pulse in the medium.

[0054] The MCU in this embodiment regularly generates ultrasonic pulses for the ultrasonic sensor. Based on the time difference between transmission and reception, the MCU accurately calculates the transmission and reception time of the ultrasonic pulses, and uses the MCU's precise timer to calculate the propagation time of the ultrasonic pulses in the medium.

[0055] Velocity Measurement and Calculation: The velocity of ultrasound varies in different media. For example, it is approximately 343 m / s in air, about 1500 m / s in water, and can be even higher in metals. Velocity calculation may involve the elastic modulus and density of the medium. The formula is c = sqrt(E / ρ), where E is the elastic modulus and ρ is the density. In practical applications, lookup tables or experimental measurements are often used to determine the speed of sound for a specific material, as theoretical calculations may require accurate medium parameters, which may not be readily available.

[0056] Thickness measurement typically uses the pulse-echo method, which involves transmitting an ultrasonic pulse, measuring the time difference between the echoes, and then calculating the thickness as d = c*t / 2. Here, t represents the time between the ultrasonic wave's transmission and reception, divided by 2 to account for the two round trips. However, this method requires a known velocity of sound in the medium, or calibration using a known thickness. If the medium is multi-layered, multiple echoes may need to be analyzed, allowing for calibration using large data sets.

[0057] Intensity measurement and calculation: The attenuation of ultrasonic waves when passing through different media. The intensity attenuation may be related to the absorption coefficient of the medium. According to the Beer-Lambert law, the intensity decays exponentially with the propagation distance. The formula is I=I0*e^(-αd), where α is the attenuation coefficient and d is the thickness. If the incident intensity and the transmitted intensity, or the reflected intensity, can be measured, the thickness d may be inferred. The attenuation coefficient is affected by many factors, such as material heterogeneity, temperature, frequency, etc., and the intensity change needs to be accurately measured, which may be difficult. However, in this device, the signal strength is only an auxiliary parameter of the measurement and has little effect on the accuracy. It is mainly used in conjunction with the speed to calculate the thickness of the dropped object.

[0058] Temperature compensation method, because temperature changes will cause changes in sound speed. Different materials may have different temperature coefficients. The compensation method may include real-time temperature measurement, and then adjusting the sound speed value in the calculation according to the relationship between temperature and sound speed (obtained by looking up a table or experimental data). Install a temperature sensor in the actual measurement system to monitor the ambient temperature in real time and perform dynamic corrections. Temperature compensation: Measure the temperature T and adjust the value of c according to the sound speed temperature coefficient of the material. For example, for water, the empirical formula for the change of sound speed with temperature may be c(T) = 1402.5 + 488T - 482T. 2 +135T 3 , or other similar polynomials. For other materials, it may be necessary to find the corresponding temperature-speed of sound relationship or determine it through experiments.

[0059] In this embodiment, the actual thickness of the dropped object is accurately obtained by the temperature compensation method as follows:

[0060] S1. When the temperature rises, the elastic modulus decreases and the speed of sound decreases. The temperature correction formula for the elastic modulus is as follows:

[0061] E(T)=E0[1-β(T-T0)];

[0062] Where E(T) represents the temperature-corrected elastic modulus at the current temperature T; E0 represents the elastic modulus at the reference temperature T0; T represents the current temperature; β represents the temperature coefficient of the elastic modulus; the temperature coefficient of the elastic modulus β is 0.01-0.03 / °C;

[0063] S2. Based on the temperature correction values ​​of elastic modulus and density, the sound velocity correction formula is as follows:

[0064]

[0065] Where c(T) represents the temperature-modified speed of sound at the current temperature T; ρ represents the density of the propagation medium;

[0066] S3. The calculation formula for the final thickness d is:

[0067] Where t represents the time from ultrasonic emission to reception.

[0068] In this embodiment, when the temperature change of the propagation medium is ignored, the sound speed correction formula is as follows:

[0069]

[0070] Where C0 is the speed of sound at the reference temperature.

[0071] Example 2:

[0072] This embodiment provides a system for detecting the thickness of forest fallen objects, which includes an MCU and an ultrasonic sensor. The ultrasonic sensor is connected to the MCU and placed on the surface of the fallen objects. The MCU obtains the time difference between the emission and reception of ultrasonic pulses in the medium, and then uses the different signal strengths and speeds of ultrasonic waves propagating in the fallen objects and soil to accurately obtain the actual thickness of the fallen objects through temperature compensation.

[0073] In this embodiment, a timer (in microseconds) is deployed inside the MCU. The MCU generates ultrasonic pulses to the ultrasonic sensor at regular intervals. The timer accurately calculates the emission and reception time of the ultrasonic pulses based on the time difference between emission and reception. The MCU's precise timer is then used to calculate the propagation time of the ultrasonic pulses in the medium.

[0074] In this embodiment, the actual thickness of the dropped object is accurately obtained by the temperature compensation method as follows:

[0075] ①The temperature correction formula of elastic modulus is as follows:

[0076] E(T)=E0[1-β(T-T0)];

[0077] Where E(T) represents the temperature-corrected elastic modulus at the current temperature T; E0 represents the elastic modulus at the reference temperature T0; T represents the current temperature; β represents the temperature coefficient of the elastic modulus;

[0078] ② Based on the temperature correction values ​​of elastic modulus and density, the sound velocity correction formula is as follows:

[0079]

[0080] Where c(T) represents the temperature-modified speed of sound at the current temperature T; ρ represents the density of the propagation medium;

[0081] ③The calculation formula for the final thickness d is:

[0082] Where t represents the time from ultrasonic emission to reception.

[0083] Finally, it should be noted that 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting the thickness of forest debris accumulation, characterized in that: This method uses ultrasonic technology to place an ultrasonic sensor on the surface of the dropped object. The difference in signal strength and speed of ultrasonic waves propagating in the dropped object and the soil is used to accurately obtain the actual thickness of the dropped object through temperature compensation. Among them, the ultrasonic sensor is connected to the MCU, and the MCU's precise timer is used to calculate the time difference between the transmission and reception of the ultrasonic pulse in the medium.

2. The method for detecting the thickness of forest debris accumulation according to claim 1, characterized in that: The MCU regularly generates ultrasonic pulses for the ultrasonic sensor. Based on the time difference between transmission and reception, the MCU accurately calculates the transmission and reception time of the ultrasonic pulse, and uses the MCU's precise timer to calculate the propagation time of the ultrasonic pulse in the medium.

3. The method for detecting the thickness of forest debris accumulation according to claim 1 or 2, characterized in that: The actual thickness of the dropped object can be accurately obtained by temperature compensation method as follows: The temperature correction formula for the elastic modulus is as follows: E(T)=E0[1-β(T-T0)]; Where E(T) represents the temperature-corrected elastic modulus at the current temperature T; E0 represents the elastic modulus at the reference temperature T0; T represents the current temperature; β represents the temperature coefficient of the elastic modulus; According to the temperature correction values ​​of elastic modulus and density, the sound velocity correction formula is as follows: Where c(T) represents the temperature-modified speed of sound at the current temperature T; ρ represents the density of the propagation medium; The final thickness d is calculated as: Where t represents the time from ultrasonic emission to reception.

4. The method for detecting the thickness of forest debris accumulation according to claim 3, characterized in that: When the temperature change of the propagation medium is ignored, the sound speed correction formula is as follows: Where C0 is the speed of sound at the reference temperature.

5. The method for detecting the thickness of forest debris accumulation according to claim 3, characterized in that: The temperature coefficient β of the elastic modulus is 0.01-0.03 / ℃.

6. A forest litter accumulation thickness detection system, characterized in that: The system includes an MCU and an ultrasonic sensor. The ultrasonic sensor is connected to the MCU and placed on the surface of the dropped object. The MCU obtains the time difference between the emission and reception of the ultrasonic pulse in the medium, and then uses the different signal strength and speed of the ultrasonic wave propagating in the dropped object and the soil to accurately obtain the actual thickness of the dropped object through temperature compensation method.

7. The forest debris accumulation thickness detection system according to claim 6, characterized in that: A timer is deployed inside the MCU. The MCU periodically generates ultrasonic pulses for the ultrasonic sensor. The timer accurately calculates the emission and reception time of the ultrasonic pulse based on the time difference between transmission and reception. The MCU's precise timer is then used to calculate the propagation time of the ultrasonic pulse in the medium.

8. The forest debris accumulation thickness detection system according to claim 6 or 7, characterized in that: The actual thickness of the dropped object can be accurately obtained by temperature compensation method as follows: The temperature correction formula for the elastic modulus is as follows: E(T)=E0[1-β(T-T0)]; Where E(T) represents the temperature-corrected elastic modulus at the current temperature T; E0 represents the elastic modulus at the reference temperature T0; T represents the current temperature; β represents the temperature coefficient of the elastic modulus; According to the temperature correction values ​​of elastic modulus and density, the sound velocity correction formula is as follows: Where c(T) represents the temperature-modified speed of sound at the current temperature T; ρ represents the density of the propagation medium; The final thickness d is calculated as: Where t represents the time from ultrasonic emission to reception.

Images