A soil tension sensor device with self-diagnosis and self-calibration

Abstract

The present invention relates to a soil tension sensor device with self-diagnosis and self-calibration, characterized in that the soil tension sensor device comprises: a fluid box, a fluid pipeline, a first solenoid valve, a second solenoid valve, a soil tension sensor, a porous ceramic medium, a pressure sensor, a liquid level sensor, a drive control unit, a data processing unit, a data storage unit, and a data sending and receiving unit; the fluid box is connected to the soil tension sensor through the fluid pipeline, the liquid in the fluid box enters the liquid cavity of the soil tension sensor, a porous ceramic medium is inserted under the liquid cavity, the porous ceramic medium contacts the soil, and the liquid in the liquid cavity exchanges water with the soil through the porous ceramic medium to achieve water potential balance; the present invention uses a local data self-checking and judging method to maintain the soil tension sensor, and the grower does not need to go to the installation site regularly to conduct a comprehensive inspection and maintenance of the sensor device.

Description

Technical Field

[0001] The invention relates to the technical field of online soil moisture measurement, and in particular to a soil tension sensor device with self-diagnosis and self-calibration. Background Art

[0002] Plant growth requires an optimal environment of water, fertilizer, air, and heat, with water being the most important regulatory factor. Water is one of the important raw materials for plant photosynthesis. Knowing the appropriate soil moisture conditions can achieve the effects of saving water and fertilizer and increasing production. Therefore, real-time and accurate monitoring of farmland soil moisture has important guiding significance for agricultural production.

[0003] Soil moisture has the following functions in the growth process of plants:

[0004] 1. Soil moisture conditions directly affect crop nutrient absorption;

[0005] 2. The decomposition and mineralization of organic nutrients in the soil cannot be separated from water;

[0006] 3. Chemical fertilizers applied to the soil can only dissolve in water;

[0007] 4. Nutrient ions migrate to the root surface;

[0008] 5. The absorption of nutrients by crop roots must be achieved through water media.

[0009] Insufficient or excessive soil moisture will affect the normal growth of plants, mainly manifested in: when the soil lacks moisture, plants can easily die due to lack of water; when the soil lacks moisture, the plants will be relatively short and unable to grow normally; when the soil has sufficient moisture, the plants can grow healthily and produce high yields; when the soil has too much moisture, the roots of the plants will not be able to breathe normally and die.

[0010] Soil moisture can be measured using a soil moisture monitoring system, which can monitor and record various types of soils for a long time, or quickly measure and record in real time. At present, there are many methods for measuring soil moisture in crops, such as drying method, tensiometer method, neutron method or ray method, dielectric constant method or electromagnetic wave method, resistance method or granular array method, capacitance method, etc.

[0011] But commonly used online soil moisture measurements are usually divided into two major categories of technology: volumetry, which measures the volume percentage of water in a given amount of soil, and tensimetry, which measures the soil's water potential (tension), which is the force that plants must overcome to get the water they need.

[0012] Using the volume measurement method, different soil types will have different tensions even under the same volume measurement, and the volume information is related to local soil conditions. It is usually necessary to calibrate the measurement equipment on site, and the measurement data is easily affected by soil salinity. In actual production, there is still a certain gap between the measurement accuracy and research work based on soil volume water content and practical application. Therefore, if the soil volume water content is used to guide production, it will cause a huge waste of manpower, material resources and water resources.

[0013] Volumetric water content data are generally confusing because they don't predict how water moves, but tension measurements measure the energy state of water and can explain how it tends to move. Just as temperature defines human comfort, tension defines plant comfort. If you know soil tension, you can predict whether a plant will grow well or be stressed in any environment.

[0014] Using the tension measurement method, the soil tension sensor can directly measure the tension of water in the soil, rather than converting it by indirectly measuring electrical characteristics like other sensors. It is the only available direct measurement instrument that does not require calibration of the measured soil and is not affected by soil salinity.

[0015] While there are many different ways to estimate irrigation needs, measuring soil tension is useful if you want to know how much water is actually available in the soil because plants must overcome soil water tension to move water into their root systems.

[0016] The tensiometers currently in use are mainly composed of porous ceramic media, water chambers, vacuum gauges or pressure sensors. The porous ceramic media of the tensiometer is like an artificial root system, which imitates the ability of crops to absorb water in this situation, and can more realistically reflect the state of the plant being thirsty or having drunk enough. Through the contact and interaction between the porous ceramic medium and the soil, when the porous ceramic medium is inserted into the soil to be tested, the free water in the tube contacts the soil water through the porous ceramic medium wall, and after exchange, the water potential balance is reached. At this time, the value read from the tensiometer is the suction value of the soil water (at the porous ceramic medium). When the soil becomes dry, the soil absorbs the water inside the tensiometer through the porous ceramic medium, thereby generating measurable tension.

[0017] Tension sensors are generally installed in the wild. During long-term measurements, they need to be brought indoors in winter to prevent freezing and cracking. In hot and dry seasons, when soil measurements exceed the sensor's measurement range, the tension sensor will dry up and need to be replenished with water. The volume of gas molecules in the soil is much smaller than that of water molecules. Water molecules can move through porous ceramic media, so gases smaller than water molecules will also enter the tensiometer water cavity. Eventually, the entire tension sensor will be filled with gas, and the gas will increase the time required to reach pressure equilibrium, so regular maintenance is required, resulting in higher operating costs.

[0018] Maintenance of the tension sensor includes exhausting undissolved gas and replenishing the loss of water in the tension sensor tube. Undissolved gas in the tension sensor will accumulate in the tension sensor tube over time. For conventional tension sensors, since the water level drop may be unpredictable or nonlinear, this problem directly affects the accuracy of the tension sensor pressure reading. Therefore, manual correction is required as the water level in the tension sensor drops. However, manual correction has problems such as complex configuration and cumbersome operation. It often causes operating errors due to improper operation, resulting in inaccurate measurement values ​​and increased labor costs, which affects the promotion and use of tension sensing devices.

[0019] Chinese invention patents CN105486838B "A tensiometer and test method for measuring soil water potential that is easy to maintain and frost-resistant", CN107219346B "A new soil tensiometer and soil water potential measurement method", CN214622634U "A soil tensiometer", the soil tensiometers disclosed in these patents require manual maintenance work such as water injection and air extraction at the installation site, and do not solve the problem of self-diagnosis and self-calibration of the tension sensor device.

[0020] Therefore, it is hoped that a soil tension sensor device with self-diagnosis and self-calibration can solve the problems existing in the prior art. Summary of the invention

[0021] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a soil tension sensor device with self-diagnosis and self-calibration, which, on the one hand, solves the technical problems of cumbersome maintenance operation and complex configuration of the soil tension sensor, and on the other hand, solves the problem of increased maintenance cost caused by the need to send manual labor to on-site calibration.

[0022] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0023] The present invention provides a soil tension sensor device with self-diagnosis and self-calibration, characterized in that the soil tension sensor device comprises: a fluid box, a fluid pipeline, a first solenoid valve, a second solenoid valve, a soil tension sensor, a porous ceramic medium, a pressure sensor, a liquid level sensor, a drive control unit, a data processing unit, a data storage unit, and a data sending and receiving unit;

[0024] The fluid box is connected to the soil tension sensor through a fluid pipeline, and the liquid in the fluid box enters the liquid cavity of the soil tension sensor. A porous ceramic medium is inserted under the liquid cavity, and the porous ceramic medium contacts the soil. The liquid in the liquid cavity exchanges water with the soil through the porous ceramic medium to achieve water potential balance.

[0025] A first solenoid valve is provided at the bottom of the fluid box to control the liquid entering the liquid cavity of the soil tension sensor;

[0026] A vacuum pump is arranged above the liquid cavity of the soil tension sensor, and the vacuum pump extracts the gas in the liquid cavity;

[0027] A second solenoid valve is arranged in the liquid cavity of the soil tension sensor to isolate the first liquid cavity and the second liquid cavity of the liquid cavity, so that the second liquid cavity becomes a water seal of the first liquid cavity, ensuring that the first liquid cavity is in a closed vacuum state and ensuring that only gas-free liquid contacts the porous ceramic medium;

[0028] A pressure sensor, a temperature sensor and a liquid level sensor are arranged in the liquid cavity of the soil tension sensor. The soil tension sensor collects the pressure value, the temperature value and the liquid level value in the liquid cavity. The pressure value in the liquid cavity is the soil tension value at the porous ceramic medium.

[0029] Wherein, the pressure sensor is arranged in the first liquid cavity; a data processing unit and a data storage unit are arranged in the soil tension sensor, the data processing unit is connected to the data storage unit, the data processing unit judges and calculates the pressure value and liquid level value collected in the liquid cavity, and stores the data in the data storage unit;

[0030] A drive control unit is also provided in the soil tension sensor. The data processing unit is connected to the drive control unit. The drive control unit is respectively connected to the first solenoid valve, the second solenoid valve and the vacuum pump. The data processing unit sends a drive command to the drive control unit. The drive control unit controls the switching of the first solenoid valve, the second solenoid valve and the start and stop of the vacuum pump respectively.

[0031] Preferably, a fluid tank level sensor is provided in the fluid tank, the fluid tank level sensor is connected to the data processing unit, and sends the fluid tank level value to the data processing unit, and the data processing unit determines and calculates the fluid tank level value.

[0032] Preferably, a data sending and receiving unit is also provided in the soil tension sensor, and the data processing unit is respectively connected to the data sending and receiving units, and the data processing unit sends the pressure value, liquid level value and liquid level value of the fluid tank in the liquid cavity and the judgment calculation result to the remote server through the data sending unit; the data processing unit receives the driving command of the remote server through the data receiving unit.

[0033] Preferably, the soil tension sensor further includes a positioning unit, the data processing unit is connected to the positioning unit, and the data processing unit sends the positioning data of the soil tension sensor to a remote server via the data sending unit.

[0034] Preferably, the second solenoid valve divides the liquid chamber into a first liquid chamber and a second liquid chamber;

[0035] The liquid level sensor comprises a lower limit liquid level sensor and an upper limit liquid level sensor;

[0036] Wherein, the lower limit liquid level sensor is arranged in the first liquid cavity, and the upper limit liquid level sensor is arranged in the second liquid cavity.

[0037] Preferably, a sealing cover is provided at the top of the soil tension sensor, and a housing of the soil tension sensor is sealed and connected below the sealing cover;

[0038] A liquid injection port is provided in the sealing cover, and the fluid pipeline is connected to the second liquid cavity of the soil tension sensor through the liquid injection port;

[0039] A gas through hole is also arranged in the sealing cover, one end of the gas through hole is connected to the vacuum pump, and the other end is connected to the outside atmosphere, and the gas extracted from the liquid cavity is discharged through the gas through hole.

[0040] Preferably, the vacuum pump is provided with a gas inlet end, and the gas inlet end is wrapped with a waterproof and breathable membrane to prevent moisture in the second liquid cavity from entering the vacuum pump;

[0041] The end of the gas through hole connected to the outside atmosphere is also wrapped with a waterproof and breathable membrane to prevent external rainwater from penetrating.

[0042] Preferably, a temperature sensor is provided in the fluid box, the temperature sensor is connected to the data processing unit, and the data processing unit determines and calculates the temperature of the fluid box according to a preset temperature threshold;

[0043] The inner layer of thermal insulation material of the fluid box and the inner layer of thermal insulation material of the fluid pipeline wrap the electric heating layer, the electric heating layer is connected to the drive control unit, and the data processing unit starts the electric heating layer through the drive control unit according to the judgment value of the fluid box temperature.

[0044] The liquid level sensor comprises a lower limit liquid level sensor and an upper limit liquid level sensor;

[0045] Wherein, the lower limit liquid level sensor is arranged in the first liquid cavity, and the upper limit liquid level sensor is arranged in the second liquid cavity.

[0046] Preferably, when the liquid level value of the lower limit liquid level sensor collected by the data processing unit is less than or equal to the preset lower limit liquid level threshold, the data processing unit sends an instruction to open the second solenoid valve to the drive control unit, the second solenoid valve opens, the liquid enters the first liquid chamber from the second liquid chamber, and the data processing unit sends a drive command to start the vacuum pump to the drive control unit, and the vacuum pump extracts the gas in the liquid chamber; when the pressure value in the liquid chamber collected by the data processing unit is greater than or equal to the set pressure threshold, the data processing unit sends a drive command to close the second solenoid valve to the drive control unit, the second solenoid valve is closed, the liquid in the first liquid chamber is a gas-free liquid, and then the data processing unit sends a drive command to close the vacuum pump to the drive control unit, the data processing unit continues to send a drive command to open the first solenoid valve to the drive control unit, the liquid in the fluid box enters the second liquid chamber through the fluid pipeline, and when the liquid level value of the upper limit liquid level sensor collected by the data processing unit is greater than or equal to the liquid level upper limit threshold, the data processing unit sends a drive command to close the first solenoid valve to the drive control unit;

[0047] When the fluid tank level value collected by the data processing unit is less than the fluid tank level threshold, the data processing unit sends the positioning data of the soil tension sensor and the fluid tank level value to the remote server to alarm.

[0048] The beneficial effects of the present invention are as follows: the soil tension sensor device with self-diagnosis and self-calibration of the present invention uses local data self-checking and judgment to maintain the soil tension sensor. The grower does not need to go to the installation site regularly to conduct a comprehensive inspection and maintenance of the sensor device. The sensor device is self-checked by relying on the local data received by the data processing unit in the soil tension sensor device, thereby driving the start and stop of the vacuum pump and the solenoid valve in the soil tension sensor device, and automatically diagnosing and calibrating the soil tension sensor device. The soil tension sensor device of the present invention is covered with heat-insulating materials and can be used continuously in winter. The present invention achieves the purpose of not sending people to the site for maintenance when the soil tension sensor device actually needs maintenance, and solves the problem that most tension sensors cannot be used continuously in winter. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the external structure of the soil tension sensor device with self-diagnosis and self-calibration of the present invention;

[0050] Figure 2 It is a schematic diagram of the internal structure of the soil tension sensor device with self-diagnosis and self-calibration of the present invention;

[0051] Figure 3 Schematic diagram of electrical connections for self-diagnosis and calibration of the soil tension sensor device of the present invention. DETAILED DESCRIPTION

[0052] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0053] Embodiment 1:

[0054] The embodiment of the present invention provides a soil tension sensor device with self-diagnosis and self-calibration.

[0055] The soil tension sensor device comprises: a fluid box, a fluid pipeline, a first solenoid valve, a second solenoid valve, a soil tension sensor, a porous ceramic medium, a pressure sensor, a liquid level sensor, a drive control unit, a data processing unit, a data storage unit, and a data sending and receiving unit;

[0056] The fluid box is connected to the soil tension sensor through a fluid pipeline, and the liquid in the fluid box enters the liquid cavity of the soil tension sensor. A porous ceramic medium is inserted under the liquid cavity, and the porous ceramic medium contacts the soil. The liquid in the liquid cavity exchanges water with the soil through the porous ceramic medium to achieve water potential balance.

[0057] A first solenoid valve is provided at the bottom of the fluid box to control the liquid entering the liquid cavity of the soil tension sensor;

[0058] A vacuum pump is arranged above the liquid cavity of the soil tension sensor, and the vacuum pump extracts the gas in the liquid cavity;

[0059] A second electromagnetic valve is arranged in the liquid cavity of the soil tension sensor, so that the second liquid cavity becomes the water seal of the first liquid cavity, ensuring that the first liquid cavity is in a closed vacuum state and that no gas or liquid contacts the porous ceramic medium;

[0060] A pressure sensor, a temperature sensor and a liquid level sensor are arranged in the liquid cavity of the soil tension sensor. The soil tension sensor collects the pressure value, the temperature value and the liquid level value in the liquid cavity. The pressure value in the liquid cavity is the soil tension value at the porous ceramic medium.

[0061] A data processing unit and a data storage unit are arranged in the soil tension sensor. The data processing unit is connected to the data storage unit. The data processing unit determines and calculates the pressure value and liquid level value collected in the liquid cavity, and stores the data in the data storage unit.

[0062] A drive control unit is also provided in the soil tension sensor. The data processing unit is connected to the drive control unit. The drive control unit is respectively connected to the first solenoid valve, the second solenoid valve and the vacuum pump. The data processing unit sends a drive command to the drive control unit. The drive control unit controls the switching of the first solenoid valve, the second solenoid valve and the start and stop of the vacuum pump respectively.

[0063] Embodiment 2

[0064] like Figure 1-2 As shown, this embodiment provides a soil tension sensor device with self-diagnosis and self-calibration, including: a fluid box 7, a fluid pipeline 6, a housing handle 5, a first solenoid valve 10, a second solenoid valve 15, a soil tension sensor 8, a housing 1, a sealing cover 2, a porous ceramic medium 20, a pressure sensor 19, a fluid box level sensor 9, a drive control unit, a data processing unit, a data storage unit, and a data sending and receiving unit;

[0065] The fluid box 7 is connected to the soil tension sensor 8 through the fluid pipeline 6. The liquid in the fluid box 7 enters the liquid cavity of the soil tension sensor 8. A porous ceramic medium 20 is inserted below the liquid cavity. The porous ceramic medium 20 contacts the soil. The liquid in the liquid cavity exchanges water with the soil through the porous ceramic medium 20 to achieve water potential balance.

[0066] A first solenoid valve 10 is provided at the bottom of the fluid box 7 to control the liquid entering the liquid cavity of the soil tension sensor 8;

[0067] A vacuum pump 12 is provided above the liquid cavity of the soil tension sensor 8, and the vacuum pump 12 extracts gas from the liquid cavity;

[0068] A second electromagnetic valve 15 is arranged in the liquid cavity of the soil tension sensor, and the second electromagnetic valve 15 divides the liquid cavity into a first liquid cavity 16 and a second liquid cavity 14; the second liquid cavity becomes a water seal of the first liquid cavity, ensuring that the first liquid cavity is in a closed vacuum state and that no gas or liquid contacts the porous ceramic medium;

[0069] A pressure sensor 19, a lower limit liquid level sensor 17 and an upper limit liquid level sensor 13 are arranged in the liquid cavity of the soil tension sensor. The pressure sensor 19 is connected to the data processing unit and the gas pipeline 3 respectively through a sensor electrical connection and a gas connection line 18. The lower limit liquid level sensor 17 is arranged in the first liquid cavity 16, the upper limit liquid level sensor 13 is arranged in the second liquid cavity 14, and a temperature sensor is arranged in the liquid cavity of the soil tension sensor.

[0070] A data processing unit and a data storage unit are arranged in the soil tension sensor. The data processing unit is connected to the data storage unit. The data processing unit determines and calculates the pressure value and liquid level value collected in the liquid cavity, and stores the data in the data storage unit.

[0071] A driving control unit is also provided in the soil tension sensor, the data processing unit is connected to the driving control unit, the driving control unit is respectively connected to the first solenoid valve 10, the second solenoid valve 15 and the vacuum pump 12, the data processing unit sends a driving command to the driving control unit, and the driving control unit respectively controls the switch of the first solenoid valve 10, the second solenoid valve 15 and the start and stop of the vacuum pump 12;

[0072] A fluid tank level sensor 9 is provided in the fluid tank 7, and the fluid tank level sensor 9 is connected to the data processing unit, and sends the fluid tank level value to the data processing unit, and the data processing unit determines and calculates the fluid tank level value;

[0073] A housing handle 5 is provided at the top of the soil tension sensor 8, a sealing cover 2 is provided below the housing handle 5, and a housing 1 of the soil tension sensor is sealed and connected below the sealing cover 2;

[0074] A liquid injection port 4 is provided on the sealing cover 2, and the fluid pipeline 6 is connected to the liquid cavity of the soil tension sensor 8 through the liquid injection port 4;

[0075] A gas through hole 11 is also provided in the sealing cover 2. One end of the gas through hole 11 is connected to the vacuum pump 12, and the other end is connected to the outside atmosphere through the gas pipeline 3. The gas extracted from the liquid cavity is discharged through the gas through hole 11.

[0076] The vacuum pump 12 is provided with a gas inlet end, and the gas inlet end is wrapped with a waterproof and breathable membrane to prevent moisture in the liquid cavity from entering the vacuum pump 12;

[0077] The end of the gas through hole 11 connected to the outside atmosphere is also wrapped with a waterproof and breathable membrane to prevent external rainwater from penetrating.

[0078] A temperature sensor 21 is provided in the fluid box 7, and the temperature sensor 21 is connected to the data processing unit, and the data processing unit determines and calculates the temperature of the fluid box 7 according to a preset temperature threshold;

[0079] The inner layer of thermal insulation material of the fluid box 7 and the inner layer of thermal insulation material of the fluid pipeline 6 wrap the electric heating layer 22, and the electric heating layer 22 is connected to the drive control unit. The data processing unit starts the electric heating layer according to the judgment value of the fluid box temperature.

[0080] Embodiment 3

[0081] like Figure 3As shown, when the liquid level value of the lower limit liquid level sensor collected by the data processing unit is less than or equal to the preset lower limit liquid level threshold in the data storage unit, the data processing unit sends a command to open the second solenoid valve to the drive control unit, the second solenoid valve opens, and the liquid enters the first liquid cavity from the second liquid cavity, and the data processing unit sends a drive command to start the vacuum pump to the drive control unit, and the vacuum pump extracts the gas in the liquid cavity; when the pressure value in the liquid cavity collected by the data processing unit is greater than or equal to the pressure threshold in the data storage unit, the data processing unit sends a drive command to close the second solenoid valve to the drive control unit, the second solenoid valve is closed, and the liquid in the first liquid cavity is a gas-free liquid; then the data processing unit sends a drive command to close the vacuum pump to the drive control unit, and the data processing unit continues to send a drive command to open the first solenoid valve to the drive control unit, and the liquid in the fluid box enters the second liquid cavity through the fluid pipeline, and when the liquid level value of the upper limit liquid level sensor collected by the data processing unit is greater than or equal to the liquid level upper limit threshold in the data storage unit, the data processing unit sends a drive command to close the first solenoid valve to the drive control unit;

[0082] The data processing unit is connected to the data sending and receiving units respectively. When the fluid tank level value collected by the data processing unit is less than the fluid tank level threshold in the data storage unit, the data processing unit sends the positioning data of the soil tension sensor and the fluid tank level value to the remote server to alarm; the data processing unit receives the driving command of the remote server through the data receiving unit.

[0083] Embodiment 4

[0084] A self-diagnostic and calibrated soil tension sensor device comprises: a fluid box, a fluid pipeline connected to a sensing part, a sensing part that can be inserted into a porous ceramic medium, the sensing part having a tension sensor housing, a protective handle attached to the tension sensor housing, an independent first liquid cavity and a second liquid cavity in the tension sensor housing, one end of the first liquid cavity is connected to the porous ceramic medium, the other end of the first liquid cavity is connected to the second liquid cavity through an electromagnetic valve, the electromagnetic valve body has a waterproof protective housing and is installed in the second liquid cavity, a parameter sensor is installed in the first liquid cavity, and is connected to the outside of the sensing part through a sensor electrical connection and a gas passage, and is used to measure parameters in the porous ceramic medium inserted into the sensing part, and the tension sensor housing It is connected to the sealing cover, on which a vacuum pump is arranged, and a waterproof breathable membrane is installed on the air inlet end of the vacuum pump. The air outlet end of the vacuum pump is connected to the outside atmosphere through the gas exchange hole on the sealing cover, and a waterproof breathable membrane is arranged on the gas exchange hole to prevent external rainwater from penetrating into the vacuum pump through the gas exchange hole. The sealing cover is also provided with sealable waterproof ports for sensor electrical connection, fluid connection and gas connection, so that the fluid passage, sensor cable and sensor gas passage can be connected to external electrical circuits and pipelines through the sealing cover. The fluid box and the fluid passage are covered with thermal insulation material to prevent the fluid from freezing when the atmospheric temperature is low. A waterproof breathable membrane is installed at the end of the sensor gas passage connected to the atmosphere to prevent external fluid from penetrating into the sensor gas passage.

[0085] The parameter sensor may be selected from: an electrical sensor, a pressure sensor, a temperature sensor, an EC value sensor, an ion selective sensor, a pH value sensor, and the like.

[0086] It is understood that multiple sensing devices can be distributed throughout the field, woods, greenhouse or nursery and connected to a server in the cloud (not shown). For example, the sensing devices can be connected to the server using radio frequency, but they can also be connected by wire or using any other wireless technology, such as using LoRa, a telecom operator's 4G or 5G network, satellite communication, or using an Internet connection such as a mobile phone, or an iPad and other devices to connect to the Internet. Each sensing device can repeatedly send sensing data and can also send device self-test data, such as battery power, fluid tank liquid level, first liquid chamber, second liquid chamber liquid level data, etc. The self-test data can be simple Boolean data or HEX data, indicating that the battery power is low or the liquid level is high or low, etc. The liquid level information can be directly sensed by the relevant sensor and stored on the local electronic circuit board, and then uploaded to the server. Alternatively, the local electronic circuit board uses the stored data for self-checking, the cloud server performs signal processing on the sensed data, or a combination of the two to provide remote detection of the sensor device. Due to the above self-diagnosis function, growers do not need to go to the installation site regularly to conduct a comprehensive inspection and maintenance of the sensor device. Instead, they can rely on the data received by the local electronic circuit board or server to self-check the sensor device to drive the start and stop of the vacuum pump, solenoid valve, etc. of the sensor device system, and automatically diagnose and calibrate the sensor device. Therefore, the purpose of not sending people to the site for maintenance when the sensor device actually needs maintenance is achieved.

[0087] To help growers locate sensors in the field, forest or greenhouse, each sensor can additionally include Beidou Positioning (BDS), Global Positioning System (GPS) or any other suitable positioning system to provide the real location of the sensor. After the sensor coordinates are transmitted to the server, growers can read the exact location of each sensor on the site on the server, allowing the field monitoring software to use the exact location of each sensor to provide a very accurate map of the soil condition, which is very useful in water and fertilizer management and hydrological zoning, that is, providing specific precision irrigation for each group of plants.

[0088] In alternative embodiments, it will be appreciated that the tension sensor housing may be made of transparent or opaque material.

[0089] The outer periphery of one end of the tension sensor housing is an external thread, an O-ring is sleeved on the end of the thread, and the inner periphery of the sealing cover is an internal thread.

[0090] The sensor or a portion of the sensor, the reference port, portions of the atmospheric gas channel and the electrical wire channel, the valve and / or the gas outlet channel can be embedded (or encapsulated) in a substantially solidified material, such as a resin or a rigid tube, to stabilize and protect these components within the sensing device.

[0091] It will be appreciated that the shape of the sensing device may vary, the electronic circuit board may be integrated within the sensing device housing, and the location of the aperture in the housing may be located elsewhere. The wires may extend directly from the pressure sensor to the electronic circuit board, i.e. not in a wire channel. It will also be appreciated that the electronic circuit board may be located elsewhere than in the housing. For the tension sensor, various types of pressure sensors may be used, which may or may not compensate for temperature changes.

[0092] It should be understood that the self-diagnosis of the sensing device means that the sensing device can periodically or automatically collect data such as the fluid tank level sensor, the first liquid chamber pressure and the lower limit level sensor, the second liquid chamber upper limit level sensor, and the temperature of the porous ceramic medium, and perform edge calculation on the electronic circuit board on such data, compare them with the corresponding preset threshold data, and automatically obtain the analysis and diagnosis results.

[0093] It should be understood that the self-calibration of the sensing device is that when it is detected that the pressure in the first liquid chamber or the lower limit liquid level sensor reaches a set threshold, the electronic circuit board sends a command to automatically open the solenoid valve of the second liquid chamber, allowing the liquids in the first liquid chamber and the second liquid chamber to circulate and mix, and automatically replenish the lost liquid in the first liquid chamber under the action of gravity, and then turn on the vacuum pump to extract the gas mixed in the mixed liquid, exhaust the gas through the gas passage of the vacuum pump, and then close the solenoid valve of the second liquid chamber, so that the first liquid chamber is filled with gas-free liquid.

[0094] It should be understood that the vacuum pump is not limited to being installed on the sealing cover, but may also be installed outside the sealing cover of the sensor device and connected to the second liquid chamber through a gas passage.

[0095] It should be understood that the electronic circuit board may be replaced by any electronic or mechanical device that can process pressure data.

[0096] It should be understood that the outside of the fluid box and the fluid passage are wrapped with insulation materials to prevent the fluid from freezing when the atmospheric temperature is low.

[0097] It should be understood that the sensor device may be powered directly by the power grid or by off-grid solar power generation equipment.

[0098] The above-mentioned sensing devices can be calibrated at the factory, that is, the readings obtained from the sensor (in milliamperes or millivolts) are automatically converted to conventional parameter readings by the electronics, so that there is no need to run the conversion.

[0099] As described above, it is understood that similar waterproof breathable membranes can be used with other porous media sensor devices, and the parameters measured in the liquid phase solution change accordingly. For example, it can be used with porous media sensors having pH, EC, temperature, humidity, gas or gas concentration sensing parts, where gas communication between two parts or between one part and the atmosphere is required while preventing liquid from penetrating into the porous medium.

[0100] The innovative features of the soil tension sensor device with self-diagnosis and self-calibration of the present invention include:

[0101] 1. Automatically diagnose the working status of the tension sensor;

[0102] 2. Automatic water injection solves the problem of manual on-site water replenishment. Under the premise of not increasing the volume of the tension sensor liquid cavity, a solenoid valve is connected to one end of the fluid box, the other end of the solenoid valve is connected to the fluid pipeline, and the other end of the fluid pipeline is connected to the fluid pipeline inlet on the sealing cover. When the solenoid valve is opened, the liquid can be automatically injected into the second liquid cavity under the action of gravity;

[0103] 3. The electromagnetic valve is used to automatically seal the first liquid chamber to avoid manual operation errors. Conventional tensiometers use the method of manually sealing the water chamber after manual water injection. The sealing process is cumbersome and easily causes poor sealing of the tensiometer water chamber.

[0104] 4. The vacuum pump automatically evacuates air to eliminate the gas in the liquid and automatically calibrates the accuracy and sensitivity of the tension sensor;

[0105] 5. The gas inlet end of the vacuum pump is surrounded by a fluid-impermeable membrane to prevent the fluid from being drawn into the vacuum pump;

[0106] 6. The outside of the fluid box and the fluid passage exposed to the soil are wrapped with insulation materials, so they can be used continuously in winter.

[0107] 7. Automatic water replenishment

[0108] When the soil becomes dry to a certain extent, the soil will absorb the water in the first liquid cavity through the porous ceramic medium until it is completely drained, causing the gas in the soil to invade the first liquid cavity through the porous ceramic medium, destroying the vacuum state of the tensiometer, causing the tensiometer to lose its function;

[0109] The liquid in the first liquid chamber and the airless water in the second liquid chamber are isolated by opening the second solenoid valve, and gravity can automatically inject the water in the second liquid chamber into the first liquid chamber to complete the water replenishment process.

[0110] 8. Automatic calibration

[0111] After the water replenishment is completed, the vacuum pump is started. When a specific threshold of the pressure sensor signal is detected, the second solenoid valve is closed first, and then the vacuum pump is closed, so that the gas in the liquid in the first liquid chamber is exhausted, and the closed vacuum normal working state of the first liquid chamber is restored.

[0112] 9. Daily calibration

[0113] Normally, the tensiometer needs to be maintained every 5-10 days to expel undissolved gases, which will accumulate in the tensiometer tube over time and affect the normal operation of the tensiometer.

[0114] The local electronic circuit board control circuit or the cloud backend issues a command to open the second solenoid valve and start the vacuum pump to evacuate air. When a specific threshold of the pressure sensor signal is detected, the second solenoid valve is closed first, and then the vacuum pump is turned off, thus completing the daily maintenance of the evacuation.

[0115] 10. Vacuum pump gas inlet waterproof breathable membrane

[0116] The gas inlet of the vacuum pump is isolated from the water in the second liquid chamber by a waterproof and breathable membrane to prevent the vacuum pump from being damaged by moisture inhalation. The gas outlet of the vacuum pump is also isolated from the water in the second liquid chamber by a waterproof and breathable membrane to prevent rainwater from penetrating.

[0117] 11. The liquid electric heating device of the sensing device can heat the liquid in the cavity;

[0118] In winter, it can prevent the porous ceramic medium from freezing and cracking. When the control circuit detects that the temperature in the liquid cavity is lower than the set threshold, the electric heating device is started to heat the liquid;

[0119] 12. Set a normally closed second solenoid valve in the sensor liquid chamber

[0120] The liquids in the first liquid chamber and the second liquid chamber of the sensor are usually isolated by the second solenoid valve. When the sensor performs operations such as water replenishment and air extraction calibration, the electronic circuit board controls the second solenoid valve to turn on the power and drive it to open the valve, so that the liquids in the first liquid chamber and the second liquid chamber can be connected. At the same time, the gas in the first liquid chamber can also overflow from the second solenoid valve to the second liquid chamber.

[0121] 13. Fluid tank

[0122] The liquid volume in the sensor liquid cavity is limited, and an external fluid box is used to replenish the liquid in the first liquid cavity of the tension sensor. A fluid level sensor is provided in the box, and the fluid level sensor is electrically connected to the electronic circuit board. When the liquid level is lower than the set threshold under extreme conditions, a feedback signal is given to the electronic circuit board. The electronic circuit board sends a signal to the server via wired or radio frequency, and the server issues a command to remind maintenance personnel to replenish the liquid in the fluid tank.

[0123] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments after knowing the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0124] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

Claims

1. A soil tension sensor device with self-diagnosis and self-calibration, characterized in that: The soil tension sensor device comprises: a fluid box, a fluid pipeline, a first solenoid valve, a second solenoid valve, a soil tension sensor, a porous ceramic medium, a pressure sensor, a liquid level sensor, a drive control unit, a data processing unit, a data storage unit, and a data sending and receiving unit; The fluid box is connected to the soil tension sensor through a fluid pipeline, and the liquid in the fluid box enters the liquid cavity of the soil tension sensor. A porous ceramic medium is inserted under the liquid cavity, and the porous ceramic medium contacts the soil. The liquid in the liquid cavity exchanges water with the soil through the porous ceramic medium to achieve water potential balance. A first solenoid valve is provided at the bottom of the fluid box to control the liquid entering the liquid cavity of the soil tension sensor; A vacuum pump is arranged above the liquid cavity of the soil tension sensor, and the vacuum pump extracts the gas in the liquid cavity; A second solenoid valve is provided in the liquid chamber of the soil tension sensor to ensure that no gas or liquid contacts the porous ceramic medium; A pressure sensor, a temperature sensor and a liquid level sensor are arranged in the liquid cavity of the soil tension sensor. The soil tension sensor collects the pressure value, the temperature value and the liquid level value in the liquid cavity. The pressure value in the liquid cavity is the soil tension value at the porous ceramic medium. A data processing unit and a data storage unit are arranged in the soil tension sensor. The data processing unit is connected to the data storage unit. The data processing unit determines and calculates the pressure value and liquid level value collected in the liquid cavity, and stores the data in the data storage unit. A driving control unit is also provided in the soil tension sensor, the data processing unit is connected to the driving control unit, the driving control unit is respectively connected to the first solenoid valve, the second solenoid valve and the vacuum pump, the data processing unit sends a driving command to the driving control unit, and the driving control unit respectively controls the switch of the first solenoid valve, the second solenoid valve and the start and stop of the vacuum pump; A fluid tank level sensor is arranged in the fluid tank, the medium stored in the fluid tank is airless water or other liquid, the fluid tank level sensor is connected to the data processing unit, and sends the fluid tank level value to the data processing unit, and the data processing unit judges and calculates the fluid tank level value; The second solenoid valve divides the liquid chamber into a first liquid chamber and a second liquid chamber; The liquid level sensor comprises a lower limit liquid level sensor and an upper limit liquid level sensor; Wherein, the lower limit liquid level sensor is arranged in the first liquid chamber, and the upper limit liquid level sensor is arranged in the second liquid chamber; When the liquid level value of the lower limit liquid level sensor collected by the data processing unit is less than or equal to the preset lower limit liquid level threshold, the data processing unit sends an instruction to open the second solenoid valve to the drive control unit, the second solenoid valve is opened, and the liquid enters the first liquid chamber from the second liquid chamber, and the data processing unit sends a drive command to start the vacuum pump to the drive control unit, and the vacuum pump extracts the gas in the liquid chamber; when the pressure value in the liquid chamber collected by the data processing unit is greater than or equal to the set pressure threshold, the data processing unit sends a drive command to close the second solenoid valve to the drive control unit, the second solenoid valve is closed, and the liquid in the first liquid chamber is a gas-free liquid, and then the data processing unit sends a drive command to close the vacuum pump to the drive control unit, and the data processing unit continues to send a drive command to open the first solenoid valve to the drive control unit, and the liquid in the fluid box enters the second liquid chamber through the fluid pipeline, and when the liquid level value of the upper limit liquid level sensor collected by the data processing unit is greater than or equal to the liquid level upper limit threshold, the data processing unit sends a drive command to close the first solenoid valve to the drive control unit; When the fluid tank level value collected by the data processing unit is less than or equal to the fluid tank level threshold, the data processing unit sends the positioning data of the soil tension sensor and the fluid tank level value to the remote server to alarm.

2. The soil tension sensor device with self-diagnosis and self-calibration as claimed in claim 1, characterized in that: A data sending and receiving unit is also provided in the soil tension sensor, and the data processing unit is respectively connected to the data sending and receiving units. The data processing unit sends the pressure value, liquid level value and liquid level value of the fluid box and the judgment calculation result in the liquid cavity to the remote server through the data sending unit; the data processing unit receives the driving command of the remote server through the data receiving unit.

3. The soil tension sensor device with self-diagnosis and self-calibration as claimed in claim 2, characterized in that: The soil tension sensor further includes a positioning unit. The data processing unit is connected to the positioning unit. The data processing unit sends the positioning data of the soil tension sensor to a remote server through the data sending unit.

4. The soil tension sensor device with self-diagnosis and self-calibration as claimed in claim 1, characterized in that: A sealing cover is provided at the top of the soil tension sensor, and a housing of the soil tension sensor is sealed and connected below the sealing cover; A liquid injection port is arranged in the sealing cover, and the fluid pipeline is connected to the liquid cavity of the soil tension sensor through the liquid injection port; A gas through hole is also arranged in the sealing cover, one end of the gas through hole is connected to the vacuum pump, and the other end is connected to the outside atmosphere, and the gas extracted from the liquid cavity is discharged through the gas through hole.

5. The soil tension sensor device with self-diagnosis and self-calibration as claimed in claim 4, characterized in that: The vacuum pump is provided with a gas inlet end, and the gas inlet end is wrapped with a waterproof and breathable membrane to prevent moisture in the liquid cavity from entering the vacuum pump; The end of the gas through hole connected to the outside atmosphere is also wrapped with a waterproof and breathable membrane to prevent external rainwater from penetrating.

6. The soil tension sensor device with self-diagnosis and self-calibration as claimed in claim 1, characterized in that: A temperature sensor is provided in the fluid box, and the temperature sensor is connected to the data processing unit, and the data processing unit determines and calculates the temperature of the fluid box according to a preset temperature threshold; The inner layer of thermal insulation material of the fluid box and the inner layer of thermal insulation material of the fluid pipeline wrap the electric heating layer, the electric heating layer is connected to the drive control unit, and the data processing unit starts the electric heating layer through the drive control unit according to the judgment value of the fluid box temperature.

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