An underground soil moisture sensor

Abstract

The application discloses an underground soil humidity sensor, a sensor body is used for providing a sensor installation base, the sensor body comprises a shell, a built-in installation cavity and a sealing assembly; the built-in installation cavity is used for accommodating various functional modules, and the sealing assembly is arranged at a connecting position of the shell and each module; a data processing module is used for processing humidity original data, and the data processing module comprises a filtering unit, a calibration unit and a data conversion unit; the filtering unit is used for filtering environmental interference noise; the calibration unit prestores humidity calibration parameters of different soil types, and performs data calibration according to soil type information; a wireless transmission module is used for realizing humidity data transmission; the application avoids problems of detection sensitivity attenuation caused by adhesion of soil particles, high signal transmission energy consumption and low transmission efficiency, effectively solves problems of high data security risk and easy loss, and effectively solves problems of short sealing protection life and high false report rate.

Description

Technical Field

[0001] This invention relates to a sensor, and more particularly, to an underground soil moisture sensor. Background Technology

[0002] Soil moisture, as one of the core indicators of soil physicochemical properties, directly affects crop growth and development, soil nutrient transformation, groundwater recharge, and ecosystem balance. Its accurate monitoring and dynamic control are key technologies in modern agriculture, including precision irrigation, soil and water conservation, and ecological environment management. With the increasing demand for intelligent agriculture and refined ecological monitoring, underground soil moisture sensors have become core equipment for optimizing resource allocation, reducing water waste, and improving production efficiency, and are widely used in various scenarios such as farmland, orchards, forests, and wetlands. However, existing underground soil moisture sensors, in long-term practical applications, struggle to meet the requirements for high precision, high stability, and long lifespan in complex environments. Specifically, this includes the following aspects: 1. Most existing equipment relies on manually preset soil type parameters or single physical indicators for data calibration, and cannot automatically identify the specific composition ratio of sandy soil, clay soil, loam, and mixed soil. Due to the significant differences in dielectric constant, particle size distribution, and organic matter content among different soil types, their water adsorption characteristics and conduction laws are also different. This leads to traditional sensors being prone to large measurement errors in complex field soil environments, typically with error values ​​between ±3% and ±5%, which is difficult to meet the high-precision data requirements of scenarios such as precision irrigation. At the same time, the sensor detection end is buried underground for a long time, and is easily affected by soil particle adhesion, mineral deposition, and microbial attachment, forming an adhesive layer that blocks the detection signal, leading to a decrease in detection sensitivity and further reducing data accuracy. In addition, the wear resistance of traditional single-material anti-stick coatings is insufficient, and they are prone to wear and failure after long-term use, shortening the effective working cycle of the sensor. 2. Existing sensors in underground environments are susceptible to signal transmission issues due to factors such as soil texture, moisture content, vegetation cover, and electromagnetic interference, resulting in severe signal attenuation. Traditional sensors mostly employ fixed power enhancement or a single transmission protocol. When signal strength is insufficient, blindly increasing transmission power leads to a significant increase in energy consumption. In high-interference scenarios, switching between fixed protocols cannot effectively avoid channel congestion, causing data transmission delays and high packet loss rates. Typically, the transmission success rate is only around 85%, making it difficult to provide real-time feedback of urgent monitoring data. Furthermore, existing equipment lacks a differentiated processing mechanism for data priority. Non-urgent data competes with critical data for channel resources, further exacerbating the problem of low transmission efficiency and seriously affecting the timely issuance of subsequent control commands. 3. Soil moisture data is an important basis for agricultural production decisions and ecological environment assessments, and its security and integrity are of paramount importance. However, traditional sensors mostly use fixed key encryption methods, and the keys of the same batch of equipment are highly homogeneous, which is easy to crack and poses a risk of data leakage. At the same time, data storage mostly relies on local storage or a single cloud backup, lacking a dual protection mechanism. Once the equipment fails or the network is interrupted, data loss is likely to occur, making it impossible to trace historical monitoring data and affecting long-term trend analysis. 4. Existing sensors are difficult to adapt to the complex and harsh underground environment; the underground soil is constantly damp, and some areas also suffer from acid and alkali corrosion, heavy metal erosion, and other problems. Traditional sealing structures often use a single sealing ring or sealant, which is prone to aging and leakage under long-term effects such as soil compression and temperature changes. The sealing protection life is usually only about 3 years, which can lead to short circuit damage to the internal circuit. Anti-collision designs often use a single pressure sensor, which is prone to false alarms due to soil settlement and slight touch, with a false alarm rate as high as 30%, affecting the user's accurate judgment of the equipment status. 5. Existing equipment mostly uses a single lithium battery or solar power, which has insufficient power monitoring accuracy and cannot dynamically allocate power supply priority for each module. This results in limited battery life in the absence of sunlight, with a typical continuous working time of only about 7 days. The charging protection mechanism is simple and can only achieve basic overcharge and over-discharge protection. It does not consider the impact of temperature on charging efficiency and battery life. Charging in high or low temperature environments can easily lead to battery degradation, and the cycle life is only about 800 times, which increases the equipment maintenance cost and replacement frequency. 6. Existing sensors mostly only have data acquisition functions and lack an efficient linkage mechanism with the control and execution components. Although some devices are equipped with pumping or irrigation components, the control logic is simple, and the start and stop control is based only on the humidity data of a single depth. It is impossible to achieve accurate control by comprehensively considering the multi-layer soil moisture distribution. This can easily lead to local over-wetting or over-drying problems, making it difficult to achieve the control target of dynamic soil moisture balance. At the same time, the coordination response speed between sensors and control modules is slow and the fault diagnosis capability is insufficient. When equipment malfunctions, there is no timely warning, which affects the stability and reliability of the control system.

[0003] Therefore, those skilled in the art are dedicated to providing an underground soil moisture sensor that can effectively solve the above-mentioned technical problems. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides a subsurface soil moisture sensor, the sensor comprising: The sensor body provides a base for sensor mounting. The sensor body includes a housing, an internal mounting cavity, and a sealing assembly. The internal mounting cavity is used to accommodate various functional modules, and the sealing assembly is located at the connection between the housing and each module. A multi-layer humidity detection module is used to collect soil humidity data at different depths underground. The multi-layer humidity detection module includes at least two detection units and a data acquisition circuit. The detection units are distributed at intervals along the length of the sensor body. The data acquisition circuit is connected to each detection unit and is used to receive the raw humidity data and perform preliminary processing. The data processing module is used to process the raw humidity data. The data processing module includes a filtering unit, a calibration unit, and a data conversion unit. The filtering unit is used to filter out environmental interference noise. The calibration unit pre-stores humidity calibration parameters for different soil types and performs data calibration based on soil type information. The data conversion unit is used to convert analog humidity data into digital humidity data. A wireless transmission module is used to realize humidity data transmission. The wireless transmission module includes a signal enhancement unit, a transmission protocol adaptation unit, and a packet loss retransmission unit. The signal enhancement unit is used to enhance the transmission signal strength. The transmission protocol adaptation unit supports switching between multiple wireless transmission protocols. The packet loss retransmission unit is used to monitor the transmission status and trigger packet loss retransmission. A data storage and encryption module is used to store and protect humidity data. The data storage and encryption module includes a local storage unit, a cloud backup unit, an encryption unit, and a decryption unit. The local storage unit and the cloud backup unit are used for data storage and backup. The encryption unit is configured with an encryption key, and the decryption unit is configured with a corresponding decryption key. A protection and power supply module is used to provide protection and power supply. The protection and power supply module includes an anti-corrosion protection unit, an anti-collision unit, and a power supply unit. The anti-corrosion protection unit and the anti-collision unit are used for sensor protection. The power supply unit uses a combination of solar energy and lithium battery power. The control module is used to control the coordinated operation of each module and regulate soil moisture. The control module includes a central processing unit, a timer triggering unit, a fault diagnosis unit, and a humidity linkage control unit. The humidity linkage control unit sends start and stop commands to the pumping assembly based on the humidity data transmitted by the multi-layer humidity detection module. The pumping unit is electrically connected to the control module and is used to receive instructions from the control module to execute pumping actions. It starts pumping when the soil moisture is low and stops working when the moisture is high, thus realizing automatic regulation of soil moisture.

[0005] Furthermore, the calibration unit also includes a soil type identification subunit, which simultaneously collects characteristic parameters such as soil dielectric constant, particle size distribution, and organic matter content; through a preset multi-dimensional soil classification model, it performs principal component analysis and cluster matching on the characteristic parameters to identify the basic types of sandy soil, clay soil, loam, and the proportion of mixed soil; and to address the differences in water adsorption characteristics of different soil types, it calls a pre-stored dynamic calibration matrix to achieve type-adaptive calibration of humidity data.

[0006] Furthermore, the wireless transmission module also includes a signal detection unit, a dynamic power adjustment subunit, and a protocol priority adaptation subunit; The signal detection unit collects three parameters in real time: transmission signal strength, channel interference intensity, and data transmission error rate, generating a multi-dimensional signal quality evaluation matrix. The dynamic power adjustment subunit works in conjunction with the signal detection unit. When the signal strength is lower than a preset threshold, it does not simply activate the signal enhancement unit, but dynamically adjusts the transmission power according to the interference intensity. In low-interference scenarios, it only increases the power by 20%-30% to save energy, while in high-interference scenarios, it works in conjunction with the signal enhancement unit to achieve synergistic enhancement of power and signal amplification. The protocol priority adaptation subunit pre-stores the anti-interference characteristics and transmission rate matching models of LoRa, NB-IoT, and WiFi6 protocols. When the channel interference intensity is detected to exceed the critical value, it not only switches to the protocol with stronger anti-interference capabilities, but also adjusts the protocol transmission priority based on the urgency of the data to be transmitted. Urgent data occupies channel resources first, while non-urgent data adopts a fragmented transmission and retransmission optimization strategy.

[0007] Furthermore, the data storage and encryption module also includes a key generation unit, which is used to acquire the geographical information of the sensor deployment area, device number information, deployment timestamp and sensor hardware feature code, and generate a unique encryption key and decryption key based on the multidimensional information using an asymmetric encryption algorithm.

[0008] Furthermore, the pressure sensing and early warning component of the anti-collision unit includes a pressure sensor and an early warning signal transmitter. When the collision pressure detected by the pressure sensor is greater than a preset pressure threshold, the early warning signal transmitter sends a collision early warning signal to an external terminal.

[0009] Furthermore, the power supply unit also includes a power monitoring subunit and a charging protection subunit; The power monitoring subunit features dual-core redundant detection, collecting real-time data on the remaining power, charge / discharge cycle count, and cell temperature of the lithium battery. Algorithms predict remaining usable time and degradation trends. The charging protection subunit not only provides overcharge and over-discharge protection but also dynamically adjusts the charging current based on cell temperature: when the temperature is below 0℃, a preheating program is initiated before charging with a small 0.3C current; when the temperature is between 25℃ and 35℃, a standard 1C current is used; and when the temperature is above 45℃, charging is paused and heat dissipation is triggered to prevent battery degradation caused by high-temperature charging.

[0010] Furthermore, the power supply unit more specifically includes an energy consumption distribution subunit and a photovoltaic tracking linkage subunit; The energy consumption allocation subunit works in conjunction with the control module. Based on the available time predicted by the power monitoring subunit, it dynamically allocates the power supply priority of each module: when the power is sufficient, all modules work at full load; when the power is moderate, it reduces unnecessary transmission power of the wireless transmission module and disables the real-time backup function of the data storage and encryption module; when the power is insufficient, it only retains the core operation of the multi-layer humidity detection module and the control module, prioritizing basic data collection. When the power is sufficient, the remaining power is >60%; when the power is moderate, the remaining power is 30%-60%; and when the power is insufficient, the remaining power is <30%. The photovoltaic tracking linkage subunit communicates with the power monitoring subunit and the solar power supply components. When the remaining power of the lithium battery is detected to be less than 40% and the light intensity meets the conditions, it will link the angle adjustment mechanism of the solar panel to track the sun's position in real time to improve the photoelectric conversion efficiency by more than 30%.

[0011] Furthermore, the detection unit employs an interdigital capacitive humidity detection chip, whose detection end is equipped with a gradient structure anti-clay layer. This anti-clay layer consists of an inner polytetrafluoroethylene (PTFE) base, a middle carbon fiber reinforcement layer, and an outer nano-silica composite coating. The inner layer is formed with micron-level uneven texture through plasma etching, the middle layer enhances the coating structure strength, and the outer layer is prepared using the sol-gel method and subjected to hydrophobic modification treatment. Furthermore, the detection unit employs a capacitive humidity detection chip, and the detection end of the capacitive humidity detection chip is equipped with an anti-clay layer made of polytetrafluoroethylene (PTFE).

[0012] Furthermore, the sealing assembly includes a sealing ring and a sealing adhesive layer. The sealing ring adopts a composite structure of hydrogenated nitrile rubber and a metal skeleton, and the sealing adhesive layer is a gradient coating.

[0013] The present invention has the following beneficial effects: 1. The calibration unit of this invention includes a soil type identification subunit, which simultaneously collects characteristic parameters such as soil dielectric constant, particle size distribution, and organic matter content. It identifies soil type and mixing ratio through a multi-dimensional soil classification model and calls a dynamic calibration matrix to achieve type adaptation calibration. The detection unit adopts an interdigital capacitive chip with a gradient structure anti-clay layer. The anti-clay layer is composed of an inner polytetrafluoroethylene base, a middle carbon fiber reinforcement layer, and an outer nano-silica composite coating. The inner layer has micron-level uneven texture. The humidity measurement error is reduced to within ±1%, eliminating the need for additional auxiliary detection equipment and adapting to complex field soil dynamics. The anti-clay durability is improved by more than 3 times, and the stability of the detection signal is maintained for up to 24 months, avoiding the decrease in detection sensitivity caused by soil particle adhesion.

[0014] 2. The wireless transmission module includes a signal detection unit, a dynamic power adjustment subunit, and a protocol priority adaptation subunit. The signal detection unit collects three signal parameters to generate an evaluation matrix. The dynamic power adjustment subunit dynamically adjusts the transmission power according to the interference intensity. The protocol priority adaptation subunit pre-stores three protocol models, can switch protocols, and adjust the transmission priority according to the urgency of the data. It is equipped with a packet loss retransmission unit. The signal transmission success rate is increased from 85% to over 98%, the daily energy consumption of the wireless transmission module is reduced by 40%, the latency of emergency data transmission is controlled within 50ms, and non-urgent data is prevented from occupying channel resources, effectively solving the problems of high energy consumption and low transmission efficiency in signal transmission.

[0015] 3. The data storage and encryption module of this invention includes a key generation unit. It generates a unique key by using multi-dimensional information such as the geographic information of the sensor deployment area and the device number, and adopts an asymmetric encryption algorithm. It also has a dual mechanism of local storage and cloud backup. The key uniqueness identification accuracy reaches 100%, the cracking difficulty is increased by more than 10 times, no manual key configuration is required, and it is suitable for large-scale deployment. It avoids data leakage and loss, and effectively solves the problems of high data security risk and easy loss.

[0016] 4. The sealing components include a sealing ring with a composite structure of hydrogenated nitrile rubber and a metal skeleton, and a gradient-coated sealing layer; the anti-collision unit uses a pressure sensor with a dual-threshold trigger design, combined with a vibration sensor for auxiliary judgment, and includes a pressure sensing and early warning component; the sealing protection life is extended from 3 years to 8 years, and the sealing performance does not degrade after disassembly and maintenance, achieving IP68-level sealing protection; the false alarm rate of collision warning is reduced from 30% to below 5%, and the warning signal includes collision location and pressure intensity information, which facilitates rapid location of equipment status and effectively solves the problems of short sealing protection life and high false alarm rate.

[0017] 5. The power supply unit adopts a combination of solar energy and lithium battery power supply, including a power monitoring subunit, a charging protection subunit, an energy consumption distribution subunit, and a photovoltaic tracking linkage subunit; the cycle life of lithium battery is increased from 800 times to 1200 times, and the continuous working time of sensor in the absence of light is extended from 7 days to 15 days; the charging efficiency is increased by 30% under the same light conditions, effectively improving battery safety protection.

[0018] 6. The control module includes a humidity linkage control unit, which sends start and stop commands to the pumping components based on the multi-depth humidity data transmitted by the multi-layer humidity detection module; the control module also has a fault diagnosis unit to realize automatic soil moisture adjustment, avoid local over-wetness or over-dryness, and achieve dynamic balance; the fault diagnosis unit can detect equipment abnormalities in a timely manner and issue early warnings, improving the stability and reliability of the control system. Attached Figure Description

[0019] Figure 1This invention describes the overall structure and connection relationship of the sensor body, control module, and pumping assembly.

[0020] Figure 2 This is a schematic diagram showing the breakdown of the core sensor module in this invention.

[0021] Figure 3 This is a schematic flowchart of the soil moisture data processing procedure in this invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments: In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," 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 based on the specific circumstances.

[0024] like Figures 1 to 3 As shown, an underground soil moisture sensor includes: Sensor body 1 is used to provide a sensor mounting base. The sensor body includes a housing, an internal mounting cavity, and a sealing assembly. The housing is made of a corrosion-resistant alloy material and its outer surface is provided with an anti-slip and wear-resistant coating. The internal mounting cavity is used to accommodate various functional modules, and the sealing assembly is located at the connection between the housing and each module. A multi-layer humidity detection module is used to collect soil humidity data at different depths underground. The multi-layer humidity detection module includes at least two detection units and a data acquisition circuit. The detection units are distributed at intervals along the length of the sensor body. The data acquisition circuit is connected to each detection unit and is used to receive the raw humidity data and perform preliminary processing. The data processing module is used to process the raw humidity data. The data processing module includes a filtering unit, a calibration unit, and a data conversion unit. The filtering unit is used to filter out environmental interference noise. The calibration unit pre-stores humidity calibration parameters for different soil types and performs data calibration based on soil type information. The data conversion unit is used to convert analog humidity data into digital humidity data. A wireless transmission module is used to realize humidity data transmission. The wireless transmission module includes a signal enhancement unit, a transmission protocol adaptation unit, and a packet loss retransmission unit. The signal enhancement unit is used to enhance the transmission signal strength. The transmission protocol adaptation unit supports switching between multiple wireless transmission protocols. The packet loss retransmission unit is used to monitor the transmission status and trigger packet loss retransmission. A data storage and encryption module is used to store and protect humidity data. The data storage and encryption module includes a local storage unit, a cloud backup unit, an encryption unit, and a decryption unit. The local storage unit and the cloud backup unit are used for data storage and backup. The encryption unit is configured with an encryption key, and the decryption unit is configured with a corresponding decryption key. A protection and power supply module is used to provide protection and power supply. The protection and power supply module includes an anti-corrosion protection unit, an anti-collision unit, and a power supply unit. The anti-corrosion protection unit and the anti-collision unit are used for sensor protection. The power supply unit uses a combination of solar energy and lithium battery power. Control module 2 is used to control the coordinated operation of each module and regulate soil moisture. The control module includes a central processing unit, a timer triggering unit, a fault diagnosis unit, and a humidity linkage control unit. The humidity linkage control unit sends start and stop commands to the pumping assembly based on the humidity data transmitted by the multi-layer humidity detection module. Pumping component 3 is electrically connected to the control module and is used to receive instructions from the control module to perform pumping actions. It starts pumping when the soil moisture is low and stops working when the moisture is high, thus realizing automatic regulation of soil moisture.

[0025] The calibration unit also includes a soil type identification subunit, which simultaneously collects characteristic parameters such as soil dielectric constant, particle size distribution, and organic matter content. Through a pre-set multi-dimensional soil classification model, principal component analysis and cluster matching are performed on the characteristic parameters to identify the basic soil types (sandy, clay, loam) and the proportion of mixed soils. Considering the differences in water adsorption characteristics among different soil types, a pre-stored dynamic calibration matrix is ​​invoked to achieve type-adaptive calibration of humidity data. This solves the technical problems of low calibration accuracy and poor adaptability to mixed soils caused by traditional single-parameter identification, reducing humidity measurement error to within ±1%. Compared to existing technologies that rely on manually preset soil types or single physical parameter identification, this method requires no additional auxiliary detection equipment and can adapt to the dynamic changes in complex field soils.

[0026] The wireless transmission module also includes a signal detection unit, a dynamic power adjustment subunit, and a protocol priority adaptation subunit; The signal detection unit collects three parameters in real time: transmission signal strength, channel interference intensity, and data transmission error rate, generating a multi-dimensional signal quality evaluation matrix. The dynamic power adjustment subunit works in conjunction with the signal detection unit. When the signal strength is lower than a preset threshold, it does not simply activate the signal enhancement unit, but dynamically adjusts the transmission power according to the interference intensity. In low-interference scenarios, it only increases the power by 20%-30% to save energy, while in high-interference scenarios, it works in conjunction with the signal enhancement unit to achieve synergistic enhancement of power and signal amplification. The protocol priority adaptation subunit pre-stores the anti-interference characteristics and transmission rate matching models of LoRa, NB-IoT, and WiFi6 protocols. When the channel interference intensity is detected to exceed the critical value, it not only switches to the protocol with stronger anti-interference capabilities, but also adjusts the protocol transmission priority based on the urgency of the data to be transmitted (such as real-time monitoring data and historical backup data). Urgent data occupies channel resources first, while non-urgent data adopts a fragmented transmission and retransmission optimization strategy. This invention solves the problems of weak signal strength leading to full power enhancement, high energy consumption caused by fixed protocol switching, and increased channel congestion in the prior art. It achieves a triple effect of stable signal enhancement, energy saving, and optimized transmission efficiency: the signal transmission success rate is increased from 85% in the prior art to over 98%, while the daily energy consumption of the wireless transmission module is reduced by 40%, and the transmission delay of emergency data is controlled within 50ms.

[0027] The data storage and encryption module also includes a key generation unit. This unit acquires the geographical information of the sensor deployment area, device serial number information, deployment timestamp, and sensor hardware feature code. Based on this multi-dimensional information, it generates unique encryption and decryption keys using an asymmetric encryption algorithm. This solution addresses the problems of easily cracked fixed keys and key homogenization within the same batch of devices. Key uniqueness identification accuracy reaches 100%, increasing the difficulty of cracking by more than 10 times. Furthermore, it eliminates the need for manual key configuration, making it suitable for large-scale deployments.

[0028] The pressure sensing and early warning component of the anti-collision unit includes a pressure sensor and an early warning signal transmitter. When the collision pressure detected by the pressure sensor exceeds a preset pressure threshold, the early warning signal transmitter sends a collision early warning signal to an external terminal. In this invention, the pressure sensor adopts a dual-threshold trigger design (instantaneous impact threshold and continuous compression threshold), combined with a vibration sensor for auxiliary judgment, which solves the problem that existing single pressure detection is prone to false alarms due to soil settlement and slight touch. The false alarm rate of the early warning is reduced from 30% in the prior art to less than 5%, and the early warning signal includes collision location and pressure intensity information, which facilitates rapid location of equipment status.

[0029] The power supply unit also includes a power monitoring subunit and a charging protection subunit; The power monitoring subunit features dual-core redundant detection, collecting real-time data on the remaining power, charge / discharge cycle count, and cell temperature of the lithium battery. Algorithms predict remaining usable time and degradation trends. The charging protection subunit not only provides overcharge and over-discharge protection but also dynamically adjusts the charging current based on cell temperature: when the temperature is below 0℃, a preheating program is initiated before charging with a small 0.3C current; when the temperature is between 25℃ and 35℃, a standard 1C current is used; and when the temperature is above 45℃, charging is paused and heat dissipation is triggered to prevent battery degradation caused by high-temperature charging.

[0030] More specifically, the power supply unit also includes an energy consumption distribution subunit and a photovoltaic tracking linkage subunit; The energy consumption allocation subunit works in conjunction with the control module. Based on the available time predicted by the power monitoring subunit, it dynamically allocates the power supply priority of each module: when the power is sufficient, all modules work at full load; when the power is moderate, it reduces unnecessary transmission power of the wireless transmission module and disables the real-time backup function of the data storage and encryption module; when the power is insufficient, it only retains the core operation of the multi-layer humidity detection module and the control module, prioritizing basic data collection. When the power is sufficient, the remaining power is >60%; when the power is moderate, the remaining power is 30%-60%; and when the power is insufficient, the remaining power is <30%. The photovoltaic tracking linkage subunit communicates with the power monitoring subunit and the solar power supply component. When the remaining lithium battery power is detected to be below 40% and the light intensity meets the requirements, it activates the angle adjustment mechanism of the solar panel to track the sun's position in real time, thereby improving the photoelectric conversion efficiency by more than 30%. This solution in the present invention breaks through the single-function limitations of power monitoring and simple charge-discharge protection in the prior art, and achieves synergistic optimization of battery safety protection, intelligent energy consumption allocation, and photovoltaic charging efficiency enhancement: the cycle life of the lithium battery is increased from 800 times in the prior art to 1200 times, the charging efficiency is increased by 30% under the same light conditions, and the continuous working time of the sensor (in a dark environment) is extended from 7 days to 15 days.

[0031] The detection unit employs an interdigital capacitive humidity detection chip, with a gradient-structured anti-sticking layer at its detection end. This anti-sticking layer consists of an inner polytetrafluoroethylene (PTFE) base, a middle carbon fiber reinforcement layer, and an outer nano-silica composite coating. The inner layer is formed with micron-level textured surfaces through plasma etching, the middle layer enhances the structural strength of the coating, and the outer layer is prepared using a sol-gel method and undergoes hydrophobic modification. This gradient structure design allows the anti-sticking layer to maintain the low adhesion characteristics of PTFE while simultaneously improving wear resistance, structural stability, and soil compatibility through the synergistic effect of the middle reinforcement and the outer nano-coating. The textured surface disrupts the adsorption and adhesion of soil particles. This solves the technical problems of existing single PTFE anti-sticking layers being prone to wear and retaining soil particles even after long-term burial, leading to decreased detection accuracy. It improves the anti-sticking durability of the detection end by more than three times and extends the stability period of the detection signal to 24 months. Compared to existing planar anti-sticking layers, this design achieves synergistic optimization of anti-sticking and wear resistance without affecting humidity detection sensitivity.

[0032] The detection unit uses a capacitive humidity detection chip, and the detection end of the capacitive humidity detection chip is provided with an anti-clay layer, which is made of polytetrafluoroethylene material.

[0033] The sealing assembly includes a sealing ring and a sealing adhesive layer. The sealing ring adopts a composite structure of hydrogenated nitrile rubber and a metal skeleton, and the sealing adhesive layer is a gradient coating (inner layer for sealing, outer layer for moisture protection). This achieves IP68-level sealing protection for the built-in installation cavity, solving the problem of easy aging and leakage of existing IP68-level seals in long-term underground humid and soil-pressure environments. The sealing protection life is extended from 3 years to 8 years, and the sealing performance remains unchanged after disassembly and maintenance.

[0034] In this invention, the underground soil moisture sensor uses the sensor body as the mounting base. The outer shell is made of corrosion-resistant alloy material and has an anti-slip and wear-resistant coating on the outer surface. The sealing component achieves IP68 protection through a sealing ring and a gradient-coated sealing adhesive layer, ensuring the sealing performance and durability for long-term underground use. The built-in mounting cavity accommodates various functional modules and works with the support of the protection and power supply modules. The power supply module uses a combination of solar energy and lithium batteries. The power monitoring subunit collects the lithium battery status in real time and predicts the available time through dual-core redundancy detection. The charging protection subunit dynamically adjusts the charging strategy according to the cell temperature. The energy consumption allocation subunit allocates the power supply priority of each module according to the remaining power. When the power is below 40% and the light conditions are met, the photovoltaic tracking linkage subunit links the solar panel to track the sun to improve the photoelectric conversion efficiency. At the same time, the anti-corrosion protection unit and the anti-collision unit (dual threshold pressure sensor combined with vibration sensor) provide all-round protection for the sensors. When the collision exceeds the threshold, an early warning signal containing position and pressure information is sent.

[0035] During operation, multiple detection units of the multi-layer humidity detection module are distributed at intervals along the length of the module. An interdigital capacitive chip with a gradient anti-clay layer collects raw soil moisture data at different depths. After preliminary processing by the data acquisition circuit, the data is transmitted to the data processing module. First, a filtering unit removes environmental interference noise. Then, a calibration unit identifies the soil type by collecting multiple soil characteristic parameters and uses a dynamic calibration matrix to complete data calibration (error ≤ ±1%). Next, a data conversion unit converts the analog data into digital data. The processed humidity data is then stored locally and backed up to the cloud by the data storage and encryption module. A key generation unit uses asymmetric encryption based on multi-dimensional information. The encryption algorithm generates a unique key to improve data security; the wireless transmission module collects signal-related parameters through the signal detection unit, the dynamic power adjustment subunit adjusts the transmission power according to the interference intensity, the protocol priority adaptation subunit switches between LoRa / NB-IoT / WiFi6 protocols as needed and allocates channels according to the urgency of the data, and combined with the packet loss retransmission unit, achieves efficient and stable transmission (success rate ≥98%); the control module, as the core, coordinates the collaborative work of each module, and its humidity linkage control unit sends start and stop commands to the pumping component according to the transmitted humidity data. Pumping starts when the soil moisture is low and stops when it is high, ultimately achieving accurate monitoring and automatic adjustment of soil moisture.

[0036] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A subsurface soil moisture sensor, characterized in that: include: A sensor body is used to provide a sensor mounting base, the sensor body including a housing, an internal mounting cavity and a sealing assembly; The built-in mounting cavity is used to accommodate each functional module, and the sealing component is disposed at the connection between the outer shell and each module; A multi-layer humidity detection module is used to collect soil humidity data at different depths underground. The multi-layer humidity detection module includes at least two detection units and a data acquisition circuit. The detection units are distributed at intervals along the length of the sensor body. The data acquisition circuit is connected to each detection unit and is used to receive the raw humidity data and perform preliminary processing. The data processing module is used to process the raw humidity data. The data processing module includes a filtering unit, a calibration unit, and a data conversion unit. The filtering unit is used to filter out environmental interference noise. The calibration unit pre-stores humidity calibration parameters for different soil types and performs data calibration based on soil type information. The data conversion unit is used to convert analog humidity data into digital humidity data. A wireless transmission module is used to realize humidity data transmission. The wireless transmission module includes a signal enhancement unit, a transmission protocol adaptation unit, and a packet loss retransmission unit. The signal enhancement unit is used to enhance the transmission signal strength. The transmission protocol adaptation unit supports switching between multiple wireless transmission protocols. The packet loss retransmission unit is used to monitor the transmission status and trigger packet loss retransmission. A data storage and encryption module is used to store and protect humidity data. The data storage and encryption module includes a local storage unit, a cloud backup unit, an encryption unit, and a decryption unit. The local storage unit and the cloud backup unit are used for data storage and backup. The encryption unit is configured with an encryption key, and the decryption unit is configured with a corresponding decryption key. A protection and power supply module is used to provide protection and power supply. The protection and power supply module includes an anti-corrosion protection unit, an anti-collision unit, and a power supply unit. The anti-corrosion protection unit and the anti-collision unit are used for sensor protection. The power supply unit uses a combination of solar energy and lithium battery power. The control module is used to control the coordinated operation of each module and regulate soil moisture. The control module includes a central processing unit, a timer triggering unit, a fault diagnosis unit, and a humidity linkage control unit. The humidity linkage control unit sends start and stop commands to the pumping assembly based on the humidity data transmitted by the multi-layer humidity detection module. The pumping unit is electrically connected to the control module and is used to receive instructions from the control module to execute pumping actions. It starts pumping when the soil moisture is low and stops working when the moisture is high, thus realizing automatic regulation of soil moisture.

2. The underground soil moisture sensor as described in claim 1, characterized in that, The calibration unit also includes a soil type identification subunit, which simultaneously collects characteristic parameters such as soil dielectric constant, particle size distribution, and organic matter content. Through a preset multi-dimensional soil classification model, the characteristic parameters are analyzed by principal component analysis and cluster matching to identify the basic types of sandy soil, clay soil, loam, and the proportion of mixed soil. In view of the differences in water adsorption characteristics of different soil types, a pre-stored dynamic calibration matrix is ​​called to realize the type adaptation calibration of humidity data.

3. The underground soil moisture sensor as described in claim 1, characterized in that, The wireless transmission module also includes a signal detection unit, a dynamic power adjustment subunit, and a protocol priority adaptation subunit; The signal detection unit collects three parameters in real time: transmission signal strength, channel interference intensity, and data transmission error rate, generating a multi-dimensional signal quality evaluation matrix. The dynamic power adjustment subunit works in conjunction with the signal detection unit. When the signal strength is lower than a preset threshold, it does not simply activate the signal enhancement unit, but dynamically adjusts the transmission power according to the interference intensity. In low-interference scenarios, it only increases the power by 20%-30% to save energy, while in high-interference scenarios, it works in conjunction with the signal enhancement unit to achieve synergistic enhancement of power and signal amplification. The protocol priority adaptation subunit pre-stores the anti-interference characteristics and transmission rate matching models of LoRa, NB-IoT, and WiFi6 protocols. When the channel interference intensity is detected to exceed the critical value, it not only switches to the protocol with stronger anti-interference capabilities, but also adjusts the protocol transmission priority based on the urgency of the data to be transmitted. Urgent data occupies channel resources first, while non-urgent data adopts a fragmented transmission and retransmission optimization strategy.

4. The underground soil moisture sensor as described in claim 1, characterized in that, The data storage and encryption module also includes a key generation unit, which is used to obtain the geographical information of the sensor deployment area, device number information, deployment timestamp and sensor hardware feature code, and generate a unique encryption key and decryption key based on the multidimensional information using an asymmetric encryption algorithm.

5. The underground soil moisture sensor as described in claim 1, characterized in that, The pressure sensing and early warning component of the anti-collision unit includes a pressure sensor and an early warning signal transmitter. When the collision pressure detected by the pressure sensor is greater than a preset pressure threshold, the early warning signal transmitter sends a collision early warning signal to an external terminal.

6. The underground soil moisture sensor as described in claim 1, characterized in that, The power supply unit also includes a power monitoring subunit and a charging protection subunit; The power monitoring subunit features dual-core redundant detection, collecting real-time data on the remaining power, charge / discharge cycle count, and cell temperature of the lithium battery. Algorithms predict remaining usable time and degradation trends. The charging protection subunit not only provides overcharge and over-discharge protection but also dynamically adjusts the charging current based on cell temperature: when the temperature is below 0℃, a preheating program is initiated before charging with a small 0.3C current; when the temperature is between 25℃ and 35℃, a standard 1C current is used; and when the temperature is above 45℃, charging is paused and heat dissipation is triggered to prevent battery degradation caused by high-temperature charging.

7. The underground soil moisture sensor as described in claim 6, characterized in that, More specifically, the power supply unit also includes an energy consumption distribution subunit and a photovoltaic tracking linkage subunit; The energy consumption allocation subunit works in conjunction with the control module. Based on the available time predicted by the power monitoring subunit, it dynamically allocates the power supply priority of each module: when the power is sufficient, all modules work at full load; when the power is moderate, it reduces unnecessary transmission power of the wireless transmission module and disables the real-time backup function of the data storage and encryption module; when the power is insufficient, it only retains the core operation of the multi-layer humidity detection module and the control module, prioritizing basic data collection. When the power is sufficient, the remaining power is >60%; when the power is moderate, the remaining power is 30%-60%; and when the power is insufficient, the remaining power is <30%. The photovoltaic tracking linkage subunit communicates with the power monitoring subunit and the solar power supply components. When the remaining power of the lithium battery is detected to be less than 40% and the light intensity meets the conditions, it will link the angle adjustment mechanism of the solar panel to track the sun's position in real time to improve the photoelectric conversion efficiency by more than 30%.

8. The underground soil moisture sensor as described in claim 1, characterized in that, The detection unit uses an interdigital capacitive humidity detection chip, and its detection end is equipped with a gradient structure anti-clay layer. The anti-clay layer is composed of an inner polytetrafluoroethylene base, a middle carbon fiber reinforcement layer, and an outer nano-silica composite coating. The inner layer is formed with micron-level concave and convex textures by plasma etching, the middle layer enhances the strength of the coating structure, and the outer layer is prepared by sol-gel method and subjected to hydrophobic modification treatment.

9. The underground soil moisture sensor as described in claim 1, characterized in that, The detection unit uses a capacitive humidity detection chip, and the detection end of the capacitive humidity detection chip is provided with an anti-clay layer, which is made of polytetrafluoroethylene material.

10. The underground soil moisture sensor as described in claim 1, characterized in that, The sealing assembly includes a sealing ring and a sealing adhesive layer. The sealing ring adopts a composite structure of hydrogenated nitrile rubber and a metal skeleton, and the sealing adhesive layer is a gradient coating.

Images