Multi-depth soil moisture precision measuring device

Abstract

The application discloses a multi-depth soil moisture precision measuring device, which comprises a supporting and operating part, a control system and a working measuring part, wherein the control system and the working measuring part are installed on the supporting and operating part; the supporting and operating part comprises a shell, the control system is installed in the shell; and the working measuring part is installed at the lower part of the shell.

Description

Technical Field

[0001] This invention relates to the field of soil measurement, and more particularly to a device for precise measurement of soil moisture at multiple depths. Background Technology

[0002] Soil moisture activates enzymes and plant hormones within seeds, influencing crop germination rate, nutrient absorption, and root development. As a crucial component of precision sowing, variable-depth sowing addresses the differences in soil moisture content distribution at different depths caused by evaporation and sedimentation by adjusting seed placement depth. Dynamic online acquisition of soil moisture information by multi-depth soil moisture sensors is a prerequisite for rationally planning sowing depth and achieving variable-depth sowing. Common crops such as corn, wheat, and potatoes typically have sowing depths of 3–10 cm. Therefore, soil moisture sensors need to be capable of accurately measuring soil moisture stratification within this depth range. Common soil stratification measurement devices are based on the principles of FDR or TDR, utilizing the propagation frequency or attenuation rate of electromagnetic waves in the soil to detect moisture content. However, limited by the size of the detection probe and the characteristics of electromagnetic field transmission, the resolution of these devices in the vertical direction is typically around 10 cm, often failing to meet the needs of actual agricultural production. Therefore, developing a multi-depth precision soil moisture measurement device with centimeter-level (vertical ≤1 cm) measurement accuracy could bring significant innovation to the research and development of variable-depth sowing. Summary of the Invention

[0003] Therefore, the present invention provides a multi-depth soil moisture precision measurement device, which can achieve precise measurement of soil moisture layers at 1cm intervals.

[0004] To achieve the objectives of this invention, the following technical solution is adopted:

[0005] A multi-depth soil moisture precision measurement device includes a support and operation section, a control system, and a working measurement section, wherein: the control system and the working measurement section are both mounted on the support and operation section; the support and operation section includes a housing, in which the control system is mounted; and the working measurement section is mounted on the lower part of the housing.

[0006] The aforementioned multi-depth soil moisture precision measurement device includes a base plate as its housing.

[0007] The aforementioned multi-depth soil moisture precision measurement device includes a support and operation section comprising a handle, a motor power switch, a start indicator light, and a start button; the handle, motor power switch, start indicator light, and start button are mounted on the housing.

[0008] The multi-depth soil moisture precision measurement device includes a control system comprising a controller, a controller mounting plate, a battery, wiring terminals, and a cable tray.

[0009] The aforementioned multi-depth soil moisture precision measurement device includes a controller mounting plate, a battery, wiring terminals, and a cable tray, all mounted on the bottom plate of the housing; the controller is mounted on the controller mounting plate.

[0010] The aforementioned multi-depth soil moisture precision measurement device includes a working measurement section comprising an insertion glass tube and a working part; the working part is inserted into the insertion glass tube.

[0011] The aforementioned multi-depth soil moisture precision measurement device, wherein: the upper end of the glass tube inserted into the soil passes through the mounting hole in the base plate.

[0012] The multi-depth soil moisture precision measurement device includes the following working parts: a stepper motor, a stepper motor mounting base, a glass pressure plate, a guide rod, a lead screw, a bearing seat, a rubber seat, a bearing, and a data acquisition unit.

[0013] The multi-depth soil moisture precision measurement device includes a stepper motor mounting base installed on the upper surface of a glass pressure plate, with the stepper motor fixed on the stepper motor mounting base.

[0014] The multi-depth soil moisture precision measurement device includes two guide rods inserted into a soil-entry glass tube. The upper end of the guide rod is mounted on a glass pressure plate, and the lower end is mounted on a bearing seat.

[0015] The aforementioned multi-depth soil moisture precision measurement device comprises: the upper end of the lead screw is mounted on a stepper motor, the lower end is mounted on a bearing installed in a bearing housing, and the acquisition unit is mounted on the lead screw via a threaded connection.

[0016] The aforementioned multi-depth soil moisture precision measurement device includes a bearing seat installed inside a rubber seat, which is installed at the bottom of the glass tube inserted into the soil.

[0017] The multi-depth soil moisture precision measurement device includes: a flange on the upper part of the soil-inserting glass tube, a rubber gasket installed between the flange and the base plate, and the working part inserted into the soil-inserting glass tube; a glass pressure plate on the upper part of the working part, the glass pressure plate having a groove, the flange and rubber gasket on the upper part of the soil-inserting glass tube being embedded in the groove to press the soil-inserting glass tube onto the base plate.

[0018] The aforementioned multi-depth soil moisture precision measurement device includes a data acquisition unit comprising a slide, a linear bearing, a copper nut, a lens mounting base, a lens fixing component, a cylindrical lens, a spectral sensor, and a cable fixing component.

[0019] The aforementioned multi-depth soil moisture precision measurement device comprises: two linear bearings installed in the linear bearing holes of the slide block; the linear bearings are fitted onto the guide rod; and a copper nut is installed on the slide block and threadedly connected to the lead screw.

[0020] The aforementioned multi-depth soil moisture precision measurement device includes: a spectral sensor mounted on a slide, and both the spectral sensor and the lens mounting base mounted on the slide; the lens mounting base is used to support the cylindrical lens. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the operating part;

[0022] Figure 2 This is a schematic diagram of the control system installation layout;

[0023] Figure 3 A schematic diagram showing the installation of the sensor driving components and the glass tube;

[0024] Figure 4 This is a schematic diagram of the working part structure;

[0025] Figure 5 A schematic diagram of the data acquisition unit installation structure. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-5 The specific embodiments of the present invention will be described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Obviously, the embodiments described in this invention are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] The terms "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of the invention include the specific features, structures, or characteristics described in connection with that embodiment. Therefore, the terms "comprising," "including," "having," and variations thereof in this specification mean "including but not limited to," unless otherwise specifically emphasized.

[0028] The multi-depth soil moisture precision measurement device of the present invention includes a support and operation part, a control system part, and a working measurement part.

[0029] Among them, such as Figure 1 , 2 As shown, the support and operation parts include housing 1, handle 2, motor power switch 3, start indicator light 5, and work start button 7.

[0030] The housing 1 is made of aluminum plates and aluminum angle profiles, and the whole is a cubic box. The working measuring part is installed at the bottom of the housing 1.

[0031] The housing 1 includes a base plate 101, side plates and a top plate. The base plate 101 serves as the main support and mounting bracket for the measuring device. Other components in the housing 1 are directly or indirectly mounted on the base plate 101. The housing 1 also serves to protect the control system from dust.

[0032] Handle 2 is mounted on the side of housing 1 for easy movement and carrying of the multi-depth soil moisture precision measurement device. Motor power switch 3, start indicator light 5, and start button 7 are mounted on the back of housing 1. Motor power switch 3 is the power switch for stepper motor 901, allowing for easy control of the stepper motor 901's independent power supply and preventing overheating damage from prolonged operation. Start button 7 is the start button for the multi-depth soil moisture precision measurement device; pressing and holding it for two seconds starts the device and prevents accidental activation. Start indicator light 5 indicates the start-up process; it flashes when start button 7 is pressed and held, and the system starts working when it stops flashing and remains lit. After one cycle, start indicator light 5 turns off, indicating the end of the operation. Arduino microcontroller 6 is the main controller; its signal output port is exposed through a hole on the back of housing 1 for easy data transmission and control. Arduino microcontroller 6 has a built-in Bluetooth module, supporting short-range communication for the soil moisture precision measurement device.

[0033] Figure 2 This diagram shows the installation layout of the control system for a multi-depth soil moisture precision measurement device. The control system mainly includes an Arduino microcontroller 6, a controller mounting plate 8, a battery 10, terminal blocks 11, and cable trays 12. The controller mounting plate 8, battery 10, terminal blocks 11, and cable trays 12 are all mounted on a 101 base plate. The Arduino microcontroller 6 is mounted on the controller mounting plate 8, which serves as a transitional mounting component for the Arduino microcontroller 6. This is primarily for optimizing the space configuration of the electrical control box, reducing the overall size of the device, and facilitating subsequent wiring and installation. The battery 10 supplies power to the stepper motor 901, with a battery voltage of 24V. Terminal blocks 11 are used for wiring integration. The cable trays 12 are used to integrate wiring, making the installation neater and facilitating later adjustments. The controller mounting plate 8 allows for vertical mounting of the microcontroller, saving space.

[0034] Figure 3 This is a schematic diagram of the working measurement section, which mainly includes the soil-inserting glass tube 4 and the working part 9. The working part 9, as the execution part of the multi-depth soil moisture precision measurement device, is inserted into the soil-inserting glass tube 4.

[0035] The glass tube 4 used for burying is made of wear-resistant, corrosion-resistant quartz glass with good light transmission. This minimizes the decrease in light transmittance caused by the burying process and soil moisture corrosion, and broadens the light transmission band. The glass tube 4 has excellent sealing properties, effectively isolating the soil and preventing dust from adhering to the lead screw 905, which would cause abrasive wear on the lead screw 905 and the copper nut 909c, affecting the control accuracy of the measurement depth and damaging the equipment. It also prevents dust from adhering to the lens 909f, which would affect the measurement accuracy.

[0036] The upper end of the glass tube 4 extends through the central hole in the base plate 101. During operation, an excessive gap between the glass tube 4 and the soil being tested will severely weaken the signal intensity of the reflected light, reducing the detection accuracy of the spectral sensor. Therefore, before vertically inserting the lower part of the glass tube 4 into the location to be tested in the farmland, a hole matching the external dimensions of the glass tube 4 needs to be drilled to ensure a tight fit between the glass tube 4 and the surrounding soil profile.

[0037] Figure 4 The schematic diagram shows the structure of the working part 9, which mainly includes: a stepper motor 901, a stepper motor mounting base 902, a glass pressure plate 903, a guide rod 904, a lead screw 905, a bearing housing 906, a rubber seat 907, a bearing 908, a data acquisition unit 909, and a cable 910. The stepper motor 901 provides power for moisture measurement in the multi-depth soil moisture precision measurement device. The stepper motor mounting base 902 is mounted on the upper surface of the glass pressure plate 903, serving as the mounting carrier for the stepper motor 901, which is fixed to it. The glass pressure plate 903 is an important mounting connector, through which multiple parts are connected to the base plate 101.

[0038] Two guide rods 904 are inserted into the soil-insertion glass tube 4. The upper end of the guide rod 904 is mounted on the glass pressure plate 903, and the lower end is mounted on the bearing seat 906. The guide rods 904 mainly guide the data acquisition unit 909, which is mounted on the two guide rods 904 and can move up and down along the guide rods 904. The upper end of the lead screw 905 is mounted on the stepper motor 901, and the lower end is mounted on the bearing 908 installed in the bearing seat 906. The acquisition unit 909 is mounted on the lead screw 905 by a threaded connection. As the stepper motor rotates, the lead screw 905 drives the data acquisition unit 909 to move up and down along the guide rods 904. During the vertical movement of the data acquisition unit 909, the distance between the data acquisition unit 909 and the soil being tested at different depths must remain consistent to avoid measurement errors caused by differences in spacing. Compared to the reel-and-wind structure widely used in soil moisture stratification sensors, the data acquisition unit 909 relies on a triangularly positioned guide rod 904 and lead screw 905 to achieve stable downward and upward movements. The bearing housing 906 serves as the mounting component for the lead screw and guide rod, and is installed within a rubber seat 907. The rubber seat 907 is installed at the bottom of the soil-inserting glass tube 4, primarily to prevent scratches on the inner wall of the glass tube 4 during installation. The rubber seat 907 and the soil-inserting glass tube 4 are interference-fitted, ensuring the perpendicularity of the guide rod 904 and lead screw 905 through a tight fit. The data acquisition unit 909 is the data acquisition mounting component. The cable 910 is used to power the data acquisition unit 909 and transmit data; the cable 910 passes through a slot in the glass pressure plate 903 and connects to the Arduino microcontroller 6.

[0039] like Figure 3 , 4 As shown, the upper part of the buried glass tube 4 is provided with a flange, and a rubber gasket 12 is installed between the flange and the base plate 101. The working part 9 is inserted into the buried glass tube 4. The upper part of the working part 9 is provided with a glass pressure plate 903, which has a groove. After installation, the flange and rubber gasket 12 on the upper part of the buried glass tube 4 are embedded in the groove and press the buried glass tube 4 onto the base plate 101 to limit the position of the glass tube and ensure its perpendicularity to the base plate 101. Compared to bolt installation, this fixed installation method does not require drilling holes around the flange of the buried glass tube, thus avoiding glass flange breakage and improving the service life of the buried glass tube. The rubber gasket 12 is installed between the flange of the buried glass tube 4 and the base plate 101. The rubber gasket 12 can effectively prevent the flange of the buried glass tube 4 from cracking or breaking due to excessive local pressure during installation, and increases the pre-tightening force of the glass pressure plate 903 and the base plate 101 during installation, preventing the buried glass tube 4 from shaking. The inner diameter of the rubber gasket 12 is slightly smaller than the outer diameter of the buried glass tube 4, which can prevent soil from seeping into the inner cavity of the buried glass tube 4 through the gap between the flange and the base plate 101, thus playing a sealing role.

[0040] Figure 5 The schematic diagram shows the installation of the data acquisition unit, which mainly includes a slide 909a, a linear bearing 909b, a copper nut 909c, a lens mounting base 909d, a lens fixing component 909e, a cylindrical lens 909f, a spectral sensor 909g, and a cable fixing component 910h.

[0041] Two linear bearings 909b are installed in the linear bearing holes of the slide 909a and are limited by the flange of the copper nut 909c, which presses down on the outer ring of the linear bearing to prevent axial movement. The linear bearings 909b are fitted onto the guide rod 904, allowing the data acquisition unit 909 to move vertically along the guide rod 904. The copper nut 909c is installed on the slide 909a and threadedly connected to the lead screw 905, allowing the stepper motor 901 to control the rotation of the lead screw 905, thereby driving the copper nut 909c to move up and down, and further driving the data acquisition unit 909 to move. The spectral sensor 909g is installed on the slide 909a and has a built-in high-brightness LED that emits vis-NIR (visible-near-infrared) light. Its spectral signal receiver can receive the reflected light information of the soil being tested, helping to predict the actual moisture content of the soil. The spectral sensor 909g and the lens mount 909d are both installed on the slide 909a. The cylindrical lens 909f is made of K9 glass with an anti-reflective coating, achieving a transmittance of over 99% in the Vis band and over 95% in the NIR band. The lens mount 909d supports the cylindrical lens 909f, ensuring that the vertical distance between the cylindrical lens 909f and the spectral sensor 909g is equal to the back focal length of the cylindrical lens 909f. This integrates the emitted light from the spectral sensor 909g into parallel light with a vertical width of 10mm, preventing the emitted light from illuminating other measurement areas of the soil profile and ensuring the accuracy of the 10mm multi-depth soil moisture measurement data. The cylindrical lens 909f is completely fixed to the lens mount 909d via the lens fastener 909e. The cable fastener 909h is mounted on the slide block 909a with screws. The cable fastener 909h secures the cable 910 tightly to the slide block 909a, ensuring that the tension of the cable acts on the slide block 909a, preventing strain on the circuit solder joints of the spectral sensor 909g, which could cause a circuit break and interrupt signal transmission. The cable is fixedly connected to the spectral sensor 909g.

[0042] Before using the multi-depth soil moisture precision measurement device, a long hole matching the dimensions of the insertion glass tube 4 should be drilled at the corresponding location in the field. The insertion glass tube 4 is then inserted into the hole, ensuring the base plate 101 is in contact with the soil surface. Depending on the testing environment, the insertion glass tube 4 can be manufactured as a square or round tube. Furthermore, the Arduino microcontroller 6 is connected to a computer via a data cable or wireless Bluetooth. The desired soil depth range is set on the computer's interface; by default, three data points are collected at 1cm intervals. By changing the total length of the insertion glass tube 4, the effective measurement range of the device can be adjusted to meet the measurement needs of different crops.

[0043] Furthermore, the single-point motor power switch 3 powers the stepper motor 901. Press and hold the start button 7; the start indicator light 5 will begin to flash. When the start indicator light 5 remains steadily lit, the multi-depth soil moisture precision measurement device begins to work. At this point, the start button 7 can be released.

[0044] Furthermore, the spectral sensor 909g will first collect three sets of spectral data (α) at ​​the first depth location. l α1, α2, α3), where the spectral data α contains the light intensity values ​​of 10 wavelength channels received by the spectral sensor 909g, i.e., a = (β1, β2, ..., β3). 10 The collected data is transmitted to the host computer via the signal port. The host computer has a built-in anomaly detection model based on the isolated forest algorithm, which can automatically identify and remove abnormal data caused by non-soil materials (such as straw, gravel, etc.) in the detection environment. If there are no anomalies, the spectral data at the current depth is saved. If there are anomalies, the detection device is removed and aligned with other soil profiles in the hole, driving the 909g spectral sensor to continue working and collecting three sets of spectral data until the number of anomaly-free spectral data sets is ≥3. Due to the high fault tolerance of the anomaly detection model, the above operation is not frequently performed. The host computer retains the first three sets of anomaly-free data and uses the SG wavelength smoothing algorithm to smooth the 10 wavelength channel values ​​in each set of retained spectral data. The smoothing window width of the SG algorithm is 5, and the algorithm calculates the wavelength channel β. i and the average illuminance value including both its front and rear channels. Where i = 1, 2, ..., 10, By changing the value of i, the smoothing window is continuously moved until data smoothing for all wavelength channels is completed. After eliminating abnormal results caused by unstable factors, the average of the three retained spectral data is calculated to obtain the average light intensity corresponding to the current depth. Then, based on the soil moisture calibration equation applicable to various soil textures established by partial least squares method, the moisture value of the current location related to the spectral information is calculated.

[0045] Further, stepper motor 901 drives lead screw 905 to rotate, thereby moving data acquisition unit 909 downwards by 1 cm and stopping. Spectral sensor 909g measures a set of data, and the above steps of data anomaly identification and rejection are repeated. Then, stepper motor 901 continues to drive data acquisition unit 909 downwards by 1 cm, and this process is repeated until the required depth of soil moisture data is collected. Stepper motor 901 then reverses, moving data acquisition unit 909 upwards back to its initial position, and the indicator light turns off, completing one cycle. After multi-point measurements, the host computer generates a three-dimensional soil moisture prescription map of the measured farmland based on the geographical information of the measured locations and the soil moisture data. Users can export the prescription map from the host computer for a quick and intuitive understanding of soil moisture distribution and to formulate corresponding planting strategies.

[0046] This multi-depth soil moisture precision measurement device can achieve high-resolution soil moisture measurement within 1 cm of the designed measurement depth range in a convenient and low-cost manner. This makes up for the shortcomings of existing soil moisture detection devices that cannot accurately obtain soil moisture information at multiple depths within the shallow surface area. It fills the research gap on accurate soil moisture acquisition technology in precision crop sowing and ultimately realizes the rational planning and efficient utilization of water resources.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A multi-depth soil moisture precision measurement device, comprising a support and operation section, a control system, and a working measurement section, characterized in that: The control system and the working measurement section are both mounted on the support and operation section. The support and operation section includes a housing, in which the control system is installed. The working measurement section is installed at the bottom of the housing and includes an insertion glass tube and a working part. The housing includes a base plate, with the upper end of the insertion glass tube passing through a central hole in the base plate. The working part is inserted into the insertion glass tube, and a flange is provided at the top of the insertion glass tube. A rubber gasket is installed between the flange and the base plate. The working part includes: a stepper motor, a stepper motor mounting base, a glass pressure plate, a guide rod, a lead screw, a bearing housing, a rubber seat, a bearing, and a data acquisition unit. The stepper motor mounting base is mounted on the upper surface of the glass pressure plate. The stepper motor is fixed on the stepper motor mounting base; the guide rods include two rods, which are inserted into the glass tube. The upper end of the guide rod is mounted on the glass pressure plate, and the lower end is mounted on the bearing seat; the upper end of the lead screw is mounted on the stepper motor, and the lower end is mounted on the bearing installed in the bearing seat. The acquisition unit is mounted on the lead screw by a threaded connection; the bearing seat is installed in a rubber seat, and the rubber seat is installed at the bottom of the glass tube; the glass pressure plate has a groove, and the flange and rubber gasket at the top of the glass tube are embedded in the groove and press the glass tube onto the base plate to limit the position of the glass tube and ensure its perpendicularity to the base plate. The inner diameter of the rubber gasket is slightly smaller than the outer diameter of the glass tube.

2. The multi-depth soil moisture precision measurement device according to claim 1, characterized in that: The support and operating components include a handle, a motor power switch, a start indicator light, and a start button; the handle, motor power switch, start indicator light, and start button are mounted on the housing.

3. The multi-depth soil moisture precision measurement device according to claim 1, characterized in that: The control system includes a controller, a controller mounting plate, a battery, terminal blocks, and cable trays.

4. The multi-depth soil moisture precision measurement device according to claim 3, characterized in that: The controller mounting plate, battery, wiring terminals, and cable trays are all mounted on the bottom plate of the housing; the controller is mounted on the controller mounting plate.

5. The multi-depth soil moisture precision measurement device according to claim 1, characterized in that: The upper end of the glass tube inserted into the ground passes through the mounting hole in the base plate.

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