Underground frozen soil ice layer monitoring system and device based on multi-sensor fusion

Abstract

The invention relates to the technical field of soil monitoring and analysis, in particular to an underground frozen soil ice layer monitoring system and device based on multi-sensor fusion. Ultrasonic signals are sent and received through a sound wave monitoring unit, the surface temperature value of a probe is obtained through a temperature measuring unit, and the probe is heated through a temperature control module; constructing a wave velocity change curve through a feature extraction module and dividing the wave velocity change curve into a plurality of sub-curve segments; the surface state trend of the probe is judged according to the first analysis result of the surface state characterization quantity of the probe through the feature joint judgment module, the continuous output power determination mode of the temperature control module is selected according to the surface state trend through the power screening unit, and the ultrasonic signals collected under the continuous output power are recorded through the monitoring recording unit. The heating power is dynamically adapted according to the deicing effect of the probe and the influence phenomenon of heating on the environment, and the data acquisition accuracy of underground frozen soil ice layer monitoring is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil detection and analysis, and particularly relates to an underground frozen soil ice layer monitoring system and device based on multi-sensor fusion. BACKGROUND

[0002] In underground frozen soil ice layer monitoring, the monitoring mode of ultrasonic signals is widely used because it can reflect the core characteristics such as ice layer density, but the extremely low temperature environment in cold regions easily causes the surface of the monitoring probe to condense ice layer. The ice layer coverage will significantly interfere with the emission and reception of ultrasonic signals, causing wave velocity measurement errors and affecting the accuracy of ice layer state evaluation. In order to eliminate the interference of the probe surface ice layer, the existing technology usually uses a heating module to control the temperature of the probe to remove ice, but the traditional heating scheme mostly uses fixed power or simple adjustable power mode, which lacks precise control of the heating effect and environmental impact. If the heating power is insufficient, it is difficult to completely remove the ice layer on the surface of the probe, and it is impossible to completely eliminate the monitoring interference. If the heating power is too high or the heating method is improper, it will cause heat conduction to the underground frozen soil ice layer around the probe, causing the ice of the frozen soil body to melt, causing abnormal changes in the water content of the monitoring area, and the increase in melt water will further accelerate the melting speed of the ice, causing continuous abnormal attenuation of the wave velocity, which cannot reflect the true state of the frozen soil ice layer, and ultimately leads to distortion of the monitoring data, making it difficult to achieve accurate monitoring of the underground frozen soil ice layer.

[0003] For example, Chinese Patent Publication No. CN106771053A discloses a soil ice content detection method and device. The method comprises: obtaining detection information of soil; and obtaining a first ice content of the soil according to the detection information and a preset soil ice content model, wherein the input quantity of the soil ice content model is the detection information, and the output quantity is the first ice content. The device comprises: a power supply, a line control board, a platinum resistance probe, and at least two stainless steel probes. The platinum resistance probe and each stainless steel probe are used to detect the detection information of the soil. Each stainless steel probe and the platinum resistance probe are connected to the line control board. The line control board is used to control each stainless steel probe and the platinum resistance probe to obtain the detection information, and to obtain the first ice content of the soil according to the detection information and the preset soil ice content model.

[0004] The existing technology also has the following problems: The existing technology does not consider the problem that the heating and ice removal process on the surface of the probe can cause the surrounding frozen soil to melt. The existing technology cannot dynamically adapt the heating power according to the probe ice removal effect and the influence of heating on the environment, which affects the accuracy of data acquisition in underground frozen soil ice layer monitoring. SUMMARY

[0005] To this end, the application provides a multi-sensor fusion-based underground frozen soil ice layer monitoring system and device to overcome the problem that the prior art cannot dynamically adapt the heating power according to the probe deicing effect and the environmental impact of heating, affecting the accuracy of data acquisition for underground frozen soil ice layer monitoring.

[0006] To achieve the above-mentioned object, the application provides a multi-sensor fusion-based underground frozen soil ice layer monitoring system, comprising: a sensor module comprising an acoustic wave monitoring unit for emitting and receiving ultrasonic signals and a temperature measurement unit for acquiring a probe surface temperature value; a temperature control module connected to the sensor module for heating the probe according to a trigger signal emitted by the temperature measurement unit; The output power of the temperature control module is a gradient power that varies with time; a feature extraction module connected to the sensor module and the temperature control module respectively for acquiring acoustic wave speed in a feature extraction time window to construct a wave speed change curve, and dividing the wave speed change curve into several sub-curve segments; a feature joint determination module connected to the feature extraction module for determining a probe surface state representation according to the curve features of each sub-curve segment, and determining a surface state trend of the probe according to a first analysis result of the probe surface state representation; a continuous monitoring module connected to the feature joint determination module and the temperature control module respectively, comprising a power screening unit and a monitoring recording unit, the power screening unit being used to select the minimum output power in the gradient power as the continuous output power of the temperature control module according to the surface state trend, or to select the continuous output power of the temperature control module based on a second analysis result of the probe surface state representation; The monitoring recording unit is used to record the ultrasonic signals collected under the continuous output power.

[0007] Further, the temperature measurement unit is used to emit a trigger signal according to the determination result that the probe surface temperature value is greater than a preset temperature threshold.

[0008] Further, the feature extraction module is used to construct a wave speed change curve, wherein, The feature extraction module determines a feature extraction time window of a preset time length from the time when the trigger signal emitted by the temperature measurement unit is located; The feature extraction module establishes a rectangular coordinate system with acoustic wave speed as the vertical axis and the output power of the temperature control module as the horizontal axis, and constructs a wave speed change curve in the rectangular coordinate.

[0009] Further, the feature extraction module is used to divide the wave speed change curve into several sub-curve segments, wherein, The feature extraction module is used to determine the power range with the same output power along the horizontal axis, and divides the wave speed change curve into several sub-curve segments based on each power range.

[0010] Furthermore, the feature joint determination module is used to determine the probe surface state characterization quantity, wherein, The feature joint determination module is used to obtain the coordinates of the two endpoints on each sub-curve segment in the rectangular coordinate system, calculate the slope of the line connecting the two endpoints based on the coordinates of the two endpoints, and determine the absolute value of the slope of the sub-curve segment as the probe surface state characterization quantity.

[0011] Furthermore, the feature joint determination module is used to determine the first analysis result, wherein, The feature joint determination module sorts the probe surface state characterization quantities corresponding to each sub-curve segment in ascending order of output power, and writes the sorted probe surface state characterization quantities into the state characterization sequence. The first analysis result is whether the state representation sequence is an increasing sequence.

[0012] Furthermore, the feature joint determination module is used to determine the surface state trend of the probe, wherein, If the state characterization sequence is an increasing sequence, then the feature joint determination module determines that the surface state trend of the probe is a melting ice manifest state trend. If the state representation sequence is not an increasing sequence, the feature joint determination module determines that the surface state trend of the probe is a non-obvious melting state trend.

[0013] Furthermore, the power screening unit is used to select the continuous output power of the temperature control module, wherein, If the surface state trend of the probe is a melting and over-the-water trend, then the power screening unit selects the minimum output power in the gradient power as the continuous output power of the temperature control module. If the surface state trend of the probe is a non-obvious melting state trend, the power screening unit selects the continuous output power of the temperature control module based on the second analysis result of the probe surface state characterization quantity.

[0014] Furthermore, the power screening unit is used to select the continuous output power of the temperature control module based on the second analysis result, wherein, The power screening unit is used to screen state transition characteristic curve segments based on the probe surface state characterization quantity of each sub-curve segment, and selects the average output power of the two sub-curve segments corresponding to the first screened transition characteristic curve segment as the continuous output power of the temperature control module along the direction of increasing output power. The second analysis result is the positive or negative value of the probe surface state characterization quantity of each sub-curve segment. The state transition characteristic curve segment includes two sub-curve segments that are connected end to end and have opposite positive or negative values ​​of the probe surface state characterization quantity.

[0015] Furthermore, the present invention also provides a multi-sensor fusion-based underground permafrost ice layer monitoring device, comprising: The probe includes a housing and a heating element installed inside the housing, the heating element heating the housing by generating heat; The sensor cluster, which is set inside the probe, includes an acoustic wave monitoring unit and a temperature measurement unit; The processing terminal is electrically connected to the probe and the sensor cluster to acquire data information from the probe and the sensor cluster, and to send judgment analysis results and execution instructions to the probe.

[0016] Compared with existing technologies, the advantages of this invention are as follows: This invention emits and receives ultrasonic signals through an acoustic monitoring unit, acquires the probe surface temperature value through a temperature measurement unit, heats the probe through a temperature control module, constructs a wave velocity change curve and divides it into several sub-curve segments through a feature extraction module, determines the probe surface state trend through a feature joint judgment module based on the first analysis result of the probe surface state characterization quantity, selects the minimum output power in the gradient power as the continuous output power of the temperature control module based on the surface state trend through a power filtering unit, or selects the continuous output power of the temperature control module based on the second analysis result of the probe surface state characterization quantity, and records the ultrasonic signals collected under continuous output power through a monitoring and recording unit. This achieves dynamic adaptation of heating power based on the probe de-icing effect and the impact of heating on the environment, improving the accuracy of data acquisition for monitoring underground permafrost ice layers.

[0017] Furthermore, in this invention, the heating power of the temperature control module is a key factor affecting the melting of the ice layer on the probe surface and the surrounding permafrost environment. The ultrasonic wave velocity is also directly related to the state of the ice layer. That is, when the ice layer is present, the wave velocity is close to the characteristics of ice. After the ice layer melts, the wave velocity changes with the increase of meltwater. When the surrounding permafrost melts, the wave velocity will further decrease. The feature extraction module maps the acoustic wave velocity data collected under different heating powers to the coordinate system to construct a wave velocity change curve. Through this curve, the correlation between the heating power gradient change and the wave velocity fluctuation can be intuitively presented, and the probe de-icing process in actual monitoring can be correlated with the impact of probe heating on the surrounding environment.

[0018] Furthermore, the feature joint determination module in this invention sorts the probe surface state characterization quantities of the sub-curve segments corresponding to each fixed power range in ascending order of heating power and forms a state characterization sequence. Essentially, it uses the trend of the sequence to map the melting law of the ice layer on the probe surface during the process of increasing heating power gradient. If the sequence shows an increasing trend, it indicates that as the heating power increases, the amplitude of wave velocity change gradually intensifies. That is, the ice layer on the probe surface melts slowly in the low power stage and the melting rate of the ice layer accelerates in the high power stage, resulting in a gradual appearance of the ice-melting effect. If the sequence does not show an increasing trend, it indicates that the wave velocity change does not show a continuous intensification with the increase of power. It is possible that the purpose of low power is not to remove the ice layer, and the surrounding permafrost is gradually melted only when the power is gradually increased. This phenomenon is judged as a non-obvious state trend of ice melting. This analysis logic accurately judges the performance of the ice melting process by quantifying the increasing characteristics of the sequence, ensuring that the monitoring data can truly reflect the original state of the underground permafrost ice layer, and realizing the correlation between the probe de-icing process in actual monitoring and the impact of probe heating on the surrounding environment.

[0019] Furthermore, when the probe surface state trend is determined to be a clear melting trend, it means that as the heating power gradually increases from small to large, the amplitude of wave velocity change continues to intensify, and the melting effect of the ice layer on the probe surface gradually becomes clear. The ice layer melts slowly in the low power stage and the melting rate accelerates in the high power stage. In this state, there is an effective de-icing power, that is, the minimum output power in the gradient power can start the ice layer melting process. Therefore, the power screening unit selects the minimum output power in the gradient power as the continuous output power of the temperature control module. This power can maintain the continuous removal of the ice layer on the probe surface, avoid the ice layer from re-condensing and interfering with the monitoring, and minimize the heating power, reduce the melting interference caused by heat conduction to the surrounding permafrost, and reduce the energy consumption of the equipment. This realizes the dynamic adaptation of heating power according to the probe de-icing effect and the impact of heating on the environment, and improves the data acquisition accuracy of underground permafrost ice layer monitoring.

[0020] Furthermore, when the probe surface state trend is determined to be an inconspicuous melting trend, it indicates that the wave velocity change does not directly show a continuously aggravated melting characteristic with the increase of heating power. It is possible that the ice layer is not effectively removed at low power, and the melting of the surrounding permafrost only begins to occur with the increase of power. It is necessary to accurately locate the critical power to avoid ineffective heating and excessive interference. The power screening unit filters the state transition characteristic curve segment based on the second analysis result. This characteristic curve segment consists of two sub-curve segments connected end to end with opposite positive and negative values ​​of the characteristic quantities. Its essence is to capture the critical turning point of the ice layer state and wave velocity change trend on the probe surface during the change of heating power gradient, that is, the inflection point from the ice layer not reaching the melting purpose to the ice layer starting to melt, which affects the accuracy of wave velocity. Along the direction of increasing output power, the power screening unit selects the average output power of the two sub-curve segments corresponding to the first state transition characteristic curve segment as the continuous output power. Relying on the average value of this critical power range, it achieves the effect of starting effective de-icing and avoiding interference caused by exceeding the melting critical point. It achieves precise matching between heating power and actual de-icing needs, and ultimately avoids interference from ice layer residue and excessive melting, thereby improving the data acquisition accuracy of underground permafrost ice layer monitoring. Attached Figure Description

[0021] Figure 1 This is a system block diagram of an underground permafrost ice layer monitoring system based on multi-sensor fusion, according to an embodiment of the present invention. Figure 2 Logic flowchart for determining the continuous output power of the selected temperature control module; Figure 3 This is a schematic diagram illustrating the screening of state transition characteristic curve segments according to an embodiment of the present invention; Figure 4 This is a simplified structural diagram of the underground permafrost ice layer monitoring device according to an embodiment of the present invention; In the diagram: 1-shell, 2-heating element, 3-sound wave monitoring unit, 4-temperature measuring unit. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this invention, the terms "upper," "lower," "inner," "outer," etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0025] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Please see Figure 1 The diagram shown is a system block diagram of a multi-sensor fusion-based underground permafrost ice layer monitoring system according to an embodiment of the present invention. The multi-sensor fusion-based underground permafrost ice layer monitoring system of the present invention includes: The sensor module includes an acoustic wave monitoring unit for emitting and receiving ultrasonic signals and a temperature measuring unit for acquiring the probe surface temperature value. In this invention, the ultrasonic signal is a 50kHz pulse, and the sound wave velocity is determined by measuring the longitudinal wave propagation time. As is well known to those skilled in the art, in an environment dominated by ice content, the sound wave velocity is greater than 2500m / s, and in an environment dominated by water content, the sound wave velocity is less than 2000m / s.

[0027] A temperature control module, which is connected to the sensor module, is used to heat the probe according to the trigger signal sent by the temperature measuring unit; In this invention, the temperature control module includes an STM32 microcontroller to achieve gradient power control and output a PWM wave to adjust the power of the heating element.

[0028] The output power of the temperature control module is a gradient power that varies with time; The feature extraction module is connected to the sensor module and the temperature control module respectively, and is used to obtain the sound wave velocity within the feature extraction time window to construct the wave velocity change curve, and to divide the wave velocity change curve into several sub-curve segments. The feature joint determination module, which is connected to the feature extraction module, is used to determine the probe surface state characterization quantity based on the curve characteristics of each sub-curve segment, and to determine the probe surface state trend based on the first analysis result of the probe surface state characterization quantity. The continuous monitoring module, which is connected to the feature joint determination module and the temperature control module respectively, includes a power screening unit and a monitoring and recording unit. The power screening unit is used to select the minimum output power in the gradient power according to the surface state trend as the continuous output power of the temperature control module, or to select the continuous output power of the temperature control module based on the second analysis result of the probe surface state characterization quantity. The monitoring and recording unit is used to record the ultrasonic signals acquired under the continuous output power.

[0029] This invention does not limit the specific structure of the feature extraction module, the feature joint determination module, and the continuous monitoring module. They or their units can be constructed using logic components, such as field-programmable logic components, microprocessors, processors used in computers, etc., which will not be elaborated here.

[0030] Specifically, the preset duration in this invention can be 8 minutes; in the implementation of this invention, the gradient power that changes with time can be set as follows: the output power is 0.5W for 0min-2min, 1W for 2min-4min, 1.5W for 4min-6min, and 2W for 6min-8min.

[0031] Specifically, the temperature measuring unit is used to issue a trigger signal based on the determination that the probe surface temperature value is greater than a preset temperature threshold.

[0032] Specifically, the preset temperature threshold in this invention can be set by those skilled in the art based on monitoring experience. Preferably, the temperature threshold in this invention can be set to -2℃.

[0033] Specifically, the feature extraction module is used to construct the wave speed change curve, wherein, The feature extraction module takes the moment when the trigger signal emitted by the temperature measuring unit is located as the starting moment and determines a feature extraction time window of a preset duration. The feature extraction module establishes a rectangular coordinate system with the sound wave velocity as the vertical axis and the output power of the temperature control module as the horizontal axis, and constructs a wave velocity change curve within the rectangular coordinate system.

[0034] When the temperature measurement unit detects that the underground temperature meets the heating triggering conditions and sends a trigger signal, it means that the probe surface is prone to ice layer condensation under these environmental conditions. At this time, the feature extraction module defines a feature extraction time window of a preset duration with the trigger signal time as the starting point, so as to capture the dynamic changes of ultrasonic wave velocity during the heating process.

[0035] Those skilled in the art will understand that the heating power of the temperature control module is a key factor affecting the melting of the ice layer on the probe surface and the surrounding permafrost environment. The ultrasonic wave velocity is also directly related to the state of the ice layer. That is, when the ice layer is present, the wave velocity is close to the characteristics of ice. After the ice layer melts, the wave velocity changes with the increase of meltwater. When the surrounding permafrost melts, the wave velocity will further decrease. The feature extraction module maps the acoustic wave velocity data collected under different heating powers to the coordinate system to construct a wave velocity change curve. This curve can intuitively show the correlation between the change of heating power gradient and wave velocity fluctuation, and correlate the probe de-icing process in actual monitoring with the impact of probe heating on the surrounding environment.

[0036] Specifically, the feature extraction module is used to divide the wave speed change curve into several sub-curve segments, wherein, The feature extraction module is used to determine the power range with the same output power along the horizontal axis, and divides the wave speed change curve into several sub-curve segments based on each power range.

[0037] Specifically, the feature joint determination module is used to determine the probe surface state characterization quantity, wherein, The feature joint determination module is used to obtain the coordinates of the two endpoints on each sub-curve segment in the rectangular coordinate system, calculate the slope of the line connecting the two endpoints based on the coordinates of the two endpoints, and determine the absolute value of the slope of the curve segment as the probe surface state characterization quantity.

[0038] In this invention, the starting point and ending point of the line can be determined from the two endpoints of the sub-curve segment along the direction of increasing output power. The common data calculation method is to use the coordinates of the two endpoints of the sub-curve segment to calculate the slope of the line connecting the two endpoints, which will not be elaborated here.

[0039] Specifically, the feature joint determination module is used to determine the first analysis result, wherein, The feature joint determination module sorts the probe surface state characterization quantities corresponding to each sub-curve segment in ascending order of output power, and writes the sorted probe surface state characterization quantities into the state characterization sequence. The first analysis result is whether the state representation sequence is an increasing sequence.

[0040] Specifically, please refer to Figure 2 The diagram shown is a logic flowchart for determining the continuous output power of the selected temperature control module. The feature joint determination module is used to determine the surface state trend of the probe. If the state characterization sequence is an increasing sequence, then the feature joint determination module determines that the surface state trend of the probe is a melting ice manifest state trend. If the state representation sequence is not an increasing sequence, the feature joint determination module determines that the surface state trend of the probe is a non-obvious melting state trend.

[0041] Understandably, the feature joint judgment module sorts the probe surface state characterization quantities of the sub-curve segments corresponding to each fixed power range in ascending order of heating power, and forms a state characterization sequence. Essentially, it uses the trend of the sequence to map the melting law of the ice layer on the probe surface during the process of increasing heating power gradient. If the sequence shows an increasing trend, it means that as the heating power increases, the amplitude of wave velocity change gradually intensifies. That is, the ice layer on the probe surface melts slowly in the low power stage and the melting rate of the ice layer accelerates in the high power stage, resulting in a gradual appearance of the ice melting effect. If the sequence does not show an increasing trend, it means that the wave velocity change does not show a continuous intensification with the increase of power. There may be a situation where the ice layer cannot be effectively removed at low power, and the surrounding permafrost melts only gradually when the power is gradually increased. This phenomenon is judged as a non-obvious state trend of ice melting. This analysis logic accurately judges the performance of the ice melting process by quantifying the increasing characteristics of the sequence, ensuring that the monitoring data can truly reflect the original state of the underground permafrost ice layer.

[0042] Specifically, the power selection unit is used to select the continuous output power of the temperature control module, wherein, If the surface state trend of the probe is a melting and over-the-water trend, then the power screening unit selects the minimum output power in the gradient power as the continuous output power of the temperature control module. If the surface state trend of the probe is a non-obvious melting state trend, the power screening unit selects the continuous output power of the temperature control module based on the second analysis result of the probe surface state characterization quantity.

[0043] It is understandable that when the probe surface state trend is determined to be a clear melting trend, it means that as the heating power gradually increases from small to large, the amplitude of wave velocity change continues to intensify, and the melting effect of the ice layer on the probe surface gradually becomes clear. The ice layer melts slowly in the low power stage and the melting rate accelerates in the high power stage. In this state, there is an effective de-icing power, that is, the minimum output power in the gradient power is enough to start the ice layer melting process. Therefore, the power screening unit selects the minimum output power in the gradient power as the continuous output power of the temperature control module. This power can maintain the continuous removal of the ice layer on the probe surface, avoid the ice layer from re-condensing and interfering with the monitoring, and minimize the heating power, reduce the melting interference caused by heat conduction to the surrounding permafrost, and reduce the energy consumption of the equipment. This realizes the dynamic adaptation of heating power according to the probe de-icing effect and the phenomenon of heating on the environment, and improves the data acquisition accuracy of underground permafrost ice layer monitoring.

[0044] Specifically, the power screening unit is used to select the continuous output power of the temperature control module based on the second analysis result, wherein, The power screening unit is used to screen state transition characteristic curve segments based on the probe surface state characterization quantity of each sub-curve segment, and selects the average output power of the two sub-curve segments corresponding to the first screened transition characteristic curve segment as the continuous output power of the temperature control module along the direction of increasing output power. The second analysis result is the positive or negative value of the probe surface state characterization quantity of each sub-curve segment. The state transition characteristic curve segment includes two sub-curve segments that are connected end to end and have opposite positive or negative values ​​of the probe surface state characterization quantity.

[0045] Please see Figure 3 As shown, this is a schematic diagram of screening state transition characteristic curve segments in an embodiment of the present invention. For example, the probe surface state characterization quantity of sub-curve segment a1-a2 is positive, the probe surface state characterization quantity of sub-curve segment a2-a3 is positive, the probe surface state characterization quantity of sub-curve segment a3-a4 is negative, and the probe surface state characterization quantity of sub-curve segment a4-a5 is negative. Since the state transition characteristic curve segment includes two sub-curve segments that are connected end to end and have opposite positive and negative values ​​of probe surface state characterization quantities, the curve segment composed of sub-curve segment a2-a3 and sub-curve segment a3-a4 is determined as the transition characteristic curve segment.

[0046] It is understandable that when the probe surface state trend is determined to be a non-obvious melting trend, it indicates that the wave velocity change does not directly show a continuously aggravated melting characteristic with the increase of heating power. It is possible that the ice layer is not effectively removed at low power, and the melting of the surrounding permafrost only begins to occur with the increase of power. It is necessary to accurately locate the critical power to avoid ineffective heating and excessive interference. The power screening unit filters the state transition characteristic curve segment based on the second analysis result. This characteristic curve segment consists of two sub-curve segments connected end to end with opposite positive and negative values ​​of the characteristic quantities. Its essence is to capture the critical turning point of the ice layer state and wave velocity change trend on the probe surface during the change of heating power gradient, that is, the inflection point from the ice layer not reaching the melting purpose to the ice layer starting to melt, which affects the accuracy of wave velocity. Along the direction of increasing output power, the power screening unit selects the average output power of the two sub-curve segments corresponding to the first state transition characteristic curve segment as the continuous output power. Relying on the average value of this critical power range, it achieves the effect of starting effective de-icing and avoiding interference caused by exceeding the melting critical point. It achieves precise matching between heating power and actual de-icing needs, and ultimately avoids interference from ice layer residue and excessive melting, thereby improving the data acquisition accuracy of underground permafrost ice layer monitoring.

[0047] Specifically, please refer to Figure 4 The diagram shown is a simplified structural diagram of the underground permafrost ice layer monitoring device according to an embodiment of the present invention. The present invention also provides an underground permafrost ice layer monitoring device based on multi-sensor fusion, comprising: The probe includes a housing 1 and a heating element 2 installed inside the housing, the heating element heating the housing by generating heat; The sensor cluster, which is set inside the probe, includes an acoustic wave monitoring unit 3 and a temperature measuring unit 4; The processing terminal is electrically connected to the probe and the sensor cluster to acquire data information from the probe and the sensor cluster, and to send judgment analysis results and execution instructions to the probe.

[0048] The present invention does not limit the structure of the heating element 2, which can be a PTC heating element with an output power of 0.5W-2W. According to experiments conducted by those skilled in the art, the output power of the PTC heating element is between 0.5W and 2W, which can make the ice layer thickness on the probe surface <0.1mm and not have a significant impact on the monitoring results.

[0049] The present invention does not limit the structure of the acoustic monitoring unit 3. It can be an acoustic sensor made of piezoelectric ceramic wafers, including a transmitting end and a receiving end. Acoustic sensors are widely used in underground environments and material detection, which will not be elaborated here.

[0050] The present invention does not limit the structure of the temperature measuring unit 4, which can be a resistance temperature sensor, and will not be described in detail here.

[0051] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A monitoring system for underground permafrost ice layers based on multi-sensor fusion, characterized in that, include: The sensor module includes an acoustic wave monitoring unit for emitting and receiving ultrasonic signals and a temperature measuring unit for acquiring the probe surface temperature value. A temperature control module, which is connected to the sensor module, is used to heat the probe according to the trigger signal sent by the temperature measuring unit; The output power of the temperature control module is a gradient power that varies with time; The feature extraction module is connected to the sensor module and the temperature control module respectively, and is used to obtain the sound wave velocity within the feature extraction time window to construct the wave velocity change curve, and to divide the wave velocity change curve into several sub-curve segments. The feature joint determination module, which is connected to the feature extraction module, is used to determine the probe surface state characterization quantity based on the curve characteristics of each sub-curve segment, and to determine the probe surface state trend based on the first analysis result of the probe surface state characterization quantity. The continuous monitoring module, which is connected to the feature joint determination module and the temperature control module respectively, includes a power screening unit and a monitoring and recording unit. The power screening unit is used to select the minimum output power in the gradient power according to the surface state trend as the continuous output power of the temperature control module, or to select the continuous output power of the temperature control module based on the second analysis result of the probe surface state characterization quantity. The monitoring and recording unit is used to record the ultrasonic signals acquired under the continuous output power.

2. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 1, characterized in that, The temperature measurement unit is used to issue a trigger signal based on the determination that the probe surface temperature value is greater than a preset temperature threshold.

3. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 1, characterized in that, The feature extraction module is used to construct the wave speed variation curve, wherein, The feature extraction module takes the moment when the trigger signal emitted by the temperature measuring unit is located as the starting moment and determines a feature extraction time window of a preset duration. The feature extraction module establishes a rectangular coordinate system with the sound wave velocity as the vertical axis and the output power of the temperature control module as the horizontal axis, and constructs a wave velocity change curve within the rectangular coordinate system.

4. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 3, characterized in that, The feature extraction module is used to divide the wave speed change curve into several sub-curve segments, wherein, The feature extraction module is used to determine the power range with the same output power along the horizontal axis, and divides the wave speed change curve into several sub-curve segments based on each power range.

5. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 4, characterized in that, The feature joint determination module is used to determine the probe surface state characterization parameters, wherein, The feature joint determination module is used to obtain the coordinates of the two endpoints on each sub-curve segment in the rectangular coordinate system, calculate the slope of the line connecting the two endpoints based on the coordinates of the two endpoints, and determine the absolute value of the slope of the sub-curve segment as the probe surface state characterization quantity.

6. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 5, characterized in that, The feature joint determination module is used to determine the first analysis result, wherein, The feature joint determination module sorts the probe surface state characterization quantities corresponding to each sub-curve segment in ascending order of output power, and writes the sorted probe surface state characterization quantities into the state characterization sequence. The first analysis result is whether the state representation sequence is an increasing sequence.

7. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 6, characterized in that, The feature joint determination module is used to determine the surface state trend of the probe, wherein... If the state characterization sequence is an increasing sequence, then the feature joint determination module determines that the surface state trend of the probe is a melting ice manifest state trend. If the state characterization sequence is not an increasing sequence, the feature joint determination module determines that the surface state trend of the probe is a non-obvious melting state trend.

8. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 7, characterized in that, The power selection unit is used to select the continuous output power of the temperature control module, wherein, If the surface state trend of the probe is a melting and over-the-air trend, then the power screening unit selects the minimum output power in the gradient power as the continuous output power of the temperature control module. If the surface state trend of the probe is a non-obvious melting state trend, the power screening unit selects the continuous output power of the temperature control module based on the second analysis result of the probe surface state characterization quantity.

9. The underground permafrost ice layer monitoring system based on multi-sensor fusion according to claim 8, characterized in that, The power selection unit is used to select the continuous output power of the temperature control module based on the second analysis result, wherein, The power screening unit is used to screen state transition characteristic curve segments based on the probe surface state characterization quantity of each sub-curve segment, and selects the average output power of the two sub-curve segments corresponding to the first screened transition characteristic curve segment as the continuous output power of the temperature control module along the direction of increasing output power. The second analysis result is the positive or negative value of the probe surface state characterization quantity of each sub-curve segment. The state transition characteristic curve segment includes two sub-curve segments that are connected end to end and have opposite positive or negative values ​​of the probe surface state characterization quantity.

10. A multi-sensor fusion-based underground permafrost ice layer monitoring device, applied to the multi-sensor fusion-based underground permafrost ice layer monitoring system described in any one of claims 1-9, characterized in that, include: The probe includes a housing and a heating element installed inside the housing, the heating element heating the housing by generating heat; The sensor cluster, which is set inside the probe, includes an acoustic wave monitoring unit and a temperature measurement unit; The processing terminal is electrically connected to the probe and the sensor cluster to acquire data information from the probe and the sensor cluster, and to send judgment analysis results and execution instructions to the probe.

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