Portable soil moisture sensor calibration device and calibration method

Abstract

The invention relates to the technical field of soil moisture sensor calibration, and particularly discloses a portable soil moisture sensor calibration device and calibration method.The portable soil moisture sensor calibration device comprises a sample soil drying module, a soil sampler, a collecting and processing module, a heating module and a power module which are assembled in a box; the sample soil drying module comprises a drying box, a weighing sensor and a sample soil container, the weighing sensor is arranged in the drying box, the sample soil container is borne on the weighing sensor, and the heating module is used for heating a soil sample in the sample soil container; the collecting and processing module is electrically connected with the weighing sensor and the heating module and used for collecting weight data measured by the weighing sensor and controlling operation of the heating module. The power supply module is electrically connected with the sample soil drying module, the data acquisition and processing module and the heating module; the soil sampler is used for collecting a field soil sample and loading the collected soil sample into the soil sample container. The invention provides a portable calibration device for a soil moisture sensor.

Description

Technical Field

[0001] This application relates to the field of soil moisture sensor calibration technology, specifically to a portable soil moisture sensor calibration device and calibration method. Background Technology

[0002] In agricultural production and ecological environment monitoring, soil moisture sensors are core equipment for acquiring soil moisture data. Their measurement accuracy determines the accuracy of soil moisture assessment. Therefore, soil moisture sensors need to be calibrated regularly before and during use. Traditional soil moisture sensor calibration methods are mainly divided into two categories. One is laboratory calibration, which relies on large drying, weighing, and data processing equipment. This equipment is bulky and difficult to move, making it impossible to achieve real-time on-site calibration in fields and other scenarios. Soil samples must be taken back to the laboratory for processing. Soil samples are prone to moisture loss during transportation and storage, leading to deviations between calibration results and actual working conditions. The other is simple on-site calibration tools. These tools are mostly simple combinations of single-function components, lacking integrated drying, weighing, and data acquisition and processing modules. The calibration process requires manual recording and calculation of data, which is not only cumbersome and inefficient, but also inconvenient to carry due to the scattered components, making it difficult to meet the dual requirements of equipment portability and calibration accuracy for field operations. Summary of the Invention

[0003] To solve or at least partially solve the above-mentioned technical problems, this application provides a portable soil moisture sensor calibration device and calibration method.

[0004] In a first aspect, the present invention provides a portable soil moisture sensor calibration device, comprising a housing, a soil drying module, a soil sampler, a data acquisition and processing module, a heating module, and a power module, wherein the soil drying module, the soil sampler, the data acquisition and processing module, the heating module, and the power module are all assembled in the housing; The soil drying module includes a drying chamber, a weighing sensor, and a soil sample container. The weighing sensor is located inside the drying chamber, and the soil sample container is supported on the weighing sensor. The heating module corresponds to the soil sample container and is used to heat the soil sample inside the soil sample container. The data acquisition and processing module is electrically connected to the weighing sensor and the heating module respectively, and is used to acquire the weight data measured by the weighing sensor and control the operation of the heating module. The power module is electrically connected to the soil drying module, the data acquisition and processing module, and the heating module, respectively. The soil sampler is used to collect soil samples from the site and can put the collected soil samples into the sample container.

[0005] Optionally, the drying chamber of the soil sample drying module is provided with multiple independent soil sample containers, and each soil sample container is supported on a corresponding weighing sensor. The heating module includes multiple independent heating units, each of which corresponds to one of the soil sample containers and is used to independently heat the soil sample in the corresponding soil sample container. The drying oven is made of heat-insulating material and is used to isolate each of the sample soil containers.

[0006] Optionally, a retractable pull rod is provided on one side of the box, and multiple rollers are installed on the bottom of the box.

[0007] Secondly, the present invention also provides a soil moisture sensor calibration method, applied to the apparatus described in any of the first aspects, the method comprising the following steps: S1. Collect on-site soil samples using the soil sampler and load the soil samples into the corresponding soil sample container; S2. Obtain the initial weight data of the soil sample container containing the soil sample; S3. The soil sample in the soil sample container is heated by the heating module, and the real-time weight data of the soil sample container is continuously collected. S4. Based on the real-time weight data, determine that the soil sample has been dried, obtain the corresponding dried weight data, and calculate the actual moisture content of the soil sample based on the initial weight data and the dried weight data; S5. Simultaneously acquire the measurement readings of the soil moisture sensor to be calibrated; S6. Establish the correspondence between the measured readings and the actual moisture content, and complete the calibration of the soil moisture sensor.

[0008] Optionally, determining that the soil sample has finished drying based on the real-time weight data specifically includes: Two consecutive sets of adjacent real-time weight data are continuously selected, and the difference between the two sets of adjacent real-time weight data is calculated. Determine whether the difference value is within a preset stability range, where the preset stability range is used to characterize that the weight of the soil sample no longer changes; If the difference value is within the preset stable range, then the soil sample drying is considered complete.

[0009] Optionally, in the process of calculating the difference between two sets of adjacent real-time weight data, the difference is determined by calculating the relative rate of change of the two sets of adjacent real-time weight data, and the formula for calculating the relative rate of change is: in, For the first Next and first The relative rate of change of the real-time weight data; For the first The real-time weight data collected this time; For the first The real-time weight data collected this time; Indicates taking the first Next and first The larger value among the real-time weight data described below; The preset stability range is the relative rate of change. The preset rate of change threshold is met, which is used to characterize that the weight of the soil sample no longer changes; when When the preset rate of change threshold is reached, the difference value is determined to be within the preset stable range.

[0010] Optionally, the method further includes: The ambient temperature and the temperature of the heated area around the soil sample container were monitored while the soil sample was being heated. Determine whether the temperature of the heating zone meets the preset drying temperature and whether the ambient temperature is within the preset ambient temperature compensation range. If the temperature of the heating zone meets the preset drying temperature and the ambient temperature is within the preset ambient temperature compensation range, then temperature compensation is performed on the real-time weight data and the measurement reading of the soil moisture sensor to be calibrated based on the monitored ambient temperature. The real-time weight data, after temperature compensation correction, is used to determine the completion of soil sample drying and to calculate the actual moisture content. The measured readings, after temperature compensation correction, are used to establish a correspondence between the measured readings and the actual moisture content.

[0011] Optionally, the method further includes: Obtain the type information of the soil moisture sensor to be calibrated and the characteristic information of the soil sample; Adjust the acquisition parameters of the measurement readings based on the sensor type information; Based on the soil characteristic information, adjust the heating power of the heating module and the preset change rate threshold of the relative change rate; The soil sample is heated according to the adjusted acquisition parameters, heating power, and preset rate of change threshold. Weight data is collected, drying is determined, and calibration is performed.

[0012] Optionally, the method further includes: Each group of soil moisture sensors to be calibrated is assigned a unique calibration identifier, which is associated with the sampling depth and sampling location information of the corresponding soil sample. For the same soil moisture sensor to be calibrated, repeat the calibration steps to obtain multiple sets of calibration data; Calculate the deviation value between the actual moisture content and the measured reading in multiple sets of calibration data, and determine whether the deviation value is within the preset repeatability accuracy range; If the deviation value is within the preset repeatability range, multiple sets of calibration data are integrated to generate the final calibration curve; if the deviation value is not within the preset repeatability range, the data is resampled and calibrated.

[0013] Optionally, after loading the soil sample into the sample container in step S1, the method further includes: The initial weight data was collected three times after the soil sample was left to stand for a preset time. Calculate the discrete values ​​of the initial weight data three times, and determine whether the discrete values ​​are within a preset weight stability range; If the discrete value is not within the preset weight stability range, it is determined that the soil sample is unevenly packed. The soil sample in the soil sample container is leveled and the initial weight data is collected three times. If the discrete value is within the preset weight stability range, the soil sample is heated by the heating module at a preset power for a preset time to remove the floating water attached to the surface of the soil sample. After completing the step of removing floating water, the next step is to obtain the initial weight data of the soil sample container containing the soil sample.

[0014] The device provided by this invention has the following beneficial effects: The portable soil moisture sensor calibration device provided in this application integrates the soil drying module, soil sampler, data acquisition and processing module, heating module and power supply module into the same box, realizing the integrated design of each functional component. This avoids the problem of the inconvenience of carrying the scattered functional components of traditional calibration equipment, improves the outdoor portability of the device, and can meet the soil moisture sensor calibration needs in various field scenarios such as fields and wilderness.

[0015] Meanwhile, the built-in weighing sensor in the soil drying module directly supports the soil sample container, enabling real-time acquisition of soil sample weight data. Combined with a corresponding heating module, it can dry the soil samples collected on-site. The soil sampler can directly collect undisturbed soil samples from the site and place them into the soil sample container, avoiding interference from moisture loss during soil sample transportation. The electrical connection between the data acquisition and processing module, the weighing sensor, and the heating module enables automatic weight data acquisition and automatic control of the heating process, eliminating the need for manual data recording and equipment adjustment. This provides accurate and reliable measured data support for the calibration of soil moisture sensors, effectively assisting in the on-site calibration of soil moisture sensors and ensuring the consistency between calibration results and actual working conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of a portable soil moisture sensor calibration device provided in an embodiment of this application; Figure 2 A perspective view of a portable soil moisture sensor calibration device provided in an embodiment of this application; Figure 3 This is a side view of a portable soil moisture sensor calibration device provided in an embodiment of this application.

[0017] Reference numerals: 1. Box body; 2. Soil drying module; 3. Soil sampler; 4. Acquisition and processing module; 5. Heating module; 6. Power supply module; 7. Upper insulation cover; 11. Pull rod; 12. Roller; 21. Drying box; 22. Weighing sensor; 23. Soil sample container; 24. Partition; 51. Independent heating unit. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. It should also be noted that, for ease of description, only the parts relevant to this application are shown in the drawings, not all of them. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] See Figures 1 to 3 This invention provides a portable soil moisture sensor calibration device, including a housing 1, a soil drying module 2, a soil sampler 3, a data acquisition and processing module 4, a heating module 5, and a power module 6. The soil drying module 2, the soil sampler 3, the data acquisition and processing module 4, the heating module 5, and the power module 6 are all assembled inside the housing 1. The soil drying module 2 includes a drying box 21, a weighing sensor 22, and a soil sample container 23. The weighing sensor 22 is located inside the drying box 21, and the soil sample container 23 is supported on the weighing sensor 22. The heating module 5 corresponds to the soil sample container 23 and is used to heat the soil sample inside the soil sample container 23. The data acquisition and processing module 4 is electrically connected to the weighing sensor 22 and the heating module 5 respectively, and is used to acquire the weight data measured by the weighing sensor 22 and control the operation of the heating module 5. The power module 6 is electrically connected to the soil drying module 2, the data acquisition and processing module 4, and the heating module 5, respectively. The soil sampler 3 is used to collect soil samples from the field and can put the collected soil samples into the soil sample container 23.

[0021] The portable soil moisture sensor calibration device (hereinafter generally referred to as the device) provided in this embodiment of the invention focuses on integrated and portable design. The overall structure includes a housing 1, a soil drying module 2, a soil sampler 3, a data acquisition and processing module 4, a heating module 5, and a power supply module 6. All of the above functional modules are centrally assembled inside the housing 1, thereby reducing the dispersion of each component and facilitating outdoor carrying and on-site operation.

[0022] The soil drying module 2, as the core functional module of the device, consists of a drying chamber 21, a weighing sensor 22, and a soil sample container 23. The drying chamber 21 also includes a temperature sensor and an operation panel. The temperature sensor is used to monitor the temperature of the heating area in real time, while the operation panel is used to start and stop the device and view parameters. A data interface is also provided on the side of the chamber 1 for exporting collected data. The drying chamber 21 has an exhaust vent for venting, and the weighing sensor 22 is installed inside. The soil sample container 23 is directly supported by the weighing sensor 22. The heating module 5 is positioned corresponding to the soil sample container 23. This design uses a temperature-measuring heating method without isolation, allowing the heat generated by the heating module 5 to directly act on the soil sample inside the soil sample container 23. Simultaneously, the temperature sensor can monitor the temperature of the heating area, avoiding temperature loss and heat transfer delays caused by the isolation structure. This ensures that the weight data collected by the weighing sensor 22 accurately reflects the moisture changes of the soil sample during the heating process. The data acquisition and processing module 4 is electrically connected to the weighing sensor 22, the heating module 5, and the temperature sensor, respectively. It can receive weight data transmitted by the weighing sensor 22 and temperature data transmitted by the temperature sensor in real time, and can control the operation of the heating module 5 according to preset commands. The power supply module 6 is electrically connected to the soil drying module 2, the data acquisition and processing module 4, the heating module 5, the temperature sensor, the operation panel, and the data interface, respectively, providing stable power support for all electrical components of the device. The soil sampler 3 is an independent component with a structure adapted to the on-site soil sampling operation. It can directly collect undisturbed soil samples from different areas and put the collected soil samples into the soil sample container 23, thereby providing real soil samples for subsequent calibration work.

[0023] In practical applications, operators can directly carry the assembled device to field calibration sites such as fields and wilderness areas. Soil samples are collected from the target area using the soil sampler 3. After placing the soil samples into the sample container 23, the insulation cover 7 is closed (its inner wall can be designed as a semi-circle to improve heat distribution, and its top can also have vents for exhaust). The device is then started to begin preparations for calibration. Under the control of the acquisition and processing module 4, the heating module 5 heats the soil samples inside the sample container 23. The weighing sensor 22 continuously collects the weight data of the sample container 23 and the soil samples inside, while the temperature sensor simultaneously collects the temperature data of the heated area. All data is transmitted to the acquisition and processing module 4 for temporary storage. This design, which allows for non-isolated temperature measurement and heating, enables real-time correlation between changes in weight and temperature data, avoiding measurement deviations caused by structural isolation and improving the accuracy of data acquisition.

[0024] By integrating all functional modules into the housing 1, the device effectively improves overall portability and meets the mobile use requirements for on-site calibration. At the same time, the coordinated operation between the modules enables the heating, weight collection, and temperature monitoring of soil samples, providing stable and reliable measured data support for the on-site calibration of soil moisture sensors. This assists in completing the calibration work of the sensors and ensures that the calibration results can truly reflect the measurement status of the sensors under actual working conditions.

[0025] Continue reading Figures 1 to 2 In some embodiments, the drying box 21 of the soil sample drying module 2 is provided with multiple independent soil sample containers 23, and each soil sample container 23 is supported on a corresponding weighing sensor 22. The heating module 5 includes multiple independent heating units 51, each of which corresponds to a soil sample container 23 and is used to independently heat the soil sample in the corresponding soil sample container 23. The drying oven 21 is made of heat-insulating material and is used to isolate various soil containers 23.

[0026] Based on the aforementioned basic structure of the portable soil moisture sensor calibration device, and to adapt to the need for simultaneous processing of multiple soil samples, this embodiment of the invention specifically optimizes the soil drying module 2 and the heating module 5. The drying chamber 21 in the soil drying module 2 contains multiple independent soil sample containers 23, which are evenly distributed in an array. A weighing sensor 22 is fixedly mounted inside the drying chamber 21 corresponding to the position of each soil sample container 23, and each soil sample container 23 is stably supported on its corresponding weighing sensor 22. An insulating partition 24 corresponding to each soil sample container 23 is also added inside the drying chamber 21. The partition 24 is fixedly connected to the inner wall of the drying chamber 21, dividing the interior of the drying chamber 21 into multiple independent chambers. Each soil sample container 23 is placed in its corresponding independent chamber, further improving the isolation effect between the chambers.

[0027] The heating module 5 adopts a multi-unit independent control method, including multiple independent heating units 51. Each independent heating unit 51 is fixedly installed below or to the side of the corresponding soil sample container 23 inside the drying chamber 21, forming a one-to-one correspondence with the soil sample container 23 (or each independent heating unit corresponds to two soil sample containers 23). This allows the heat generated by each independent heating unit 51 to act on the soil sample inside the corresponding soil sample container 23. The independent heating unit 51 can be an aluminum heating plate, which can be evenly wrapped around the bottom or side wall of the soil sample container 23 to achieve uniform heating. The drying chamber 21 is made entirely of heat-insulating material. The selected heat-insulating material has both high temperature resistance and lightweight characteristics, which can not only reduce the loss of heat from the inside of the drying chamber 21 to the external environment, but also reduce the overall weight of the device, which is consistent with the portable design of the chamber 1. At the same time, the inner wall of the drying chamber 21 made of this heat-insulating material, together with the partition 24, can effectively isolate the heat transfer between the independent chambers and avoid the difference in soil sample drying rate caused by temperature interference between different chambers.

[0028] The data acquisition and processing module 4 is electrically connected to each weighing sensor 22 and each independent heating unit 51, respectively. It can receive the weight data transmitted by each weighing sensor 22 individually and can also control the start and stop status of each independent heating unit 51 individually according to actual needs. The power supply module 6 is also electrically connected to each independent heating unit 51, so that each independent heating unit 51 can receive stable power support. Multiple soil samples collected by the soil sampler 3 can be placed into different soil sample containers 23, realizing the simultaneous placement of multiple sets of soil samples.

[0029] In practical applications, operators can simultaneously load multiple soil samples from different regions or depths into corresponding soil sample containers 23. After starting the device, each independent heating unit 51 can be activated synchronously or individually under the control of the data acquisition and processing module 4 to heat the soil samples in the corresponding soil sample containers 23. Due to the heat insulation design of the drying oven 21 and the isolation effect of the partition 24, the temperatures in each chamber will not affect each other. Each weighing sensor 22 can independently collect the weight data of the corresponding soil sample container 23 and the soil sample inside, ensuring the independence and accuracy of multiple sets of data. This multi-set independent design eliminates the need for repeated sample loading and heating operations, significantly improving the efficiency of multi-set calibration preparation work. It also avoids cross-interference between different soil samples, allowing the device to adapt to the actual needs of multiple sets of parallel calibration, further expanding the applicable scenarios of the device. Moreover, the overall structure still maintains an integrated design, without affecting the portability of the device.

[0030] Continue reading Figure 3 In some embodiments, a retractable pull rod 11 is provided on one side of the box body 1, and multiple rollers 12 are installed at the bottom of the box body 1.

[0031] A retractable pull rod 11 is fixedly mounted on one side of the housing 1. The pull rod 11 can be made of high-strength aluminum alloy, which combines lightweight and high load-bearing capacity. This reduces the overall weight of the device while ensuring that the pull rod 11 is not easily deformed under tensile load. It also has good corrosion resistance and can adapt to humid and dusty outdoor environments. Rollers 12 are installed at the four corners of the bottom of the housing 1 in a rectangular arrangement to ensure the stability of the device when placed. The housing 1 can use a high-strength aluminum alloy frame and a shock-absorbing ABS engineering plastic shell. An internal shock-absorbing sponge groove is provided for placing the soil drying module 2 and other components.

[0032] In addition, a carrying handle can be added to the top of the housing 1. The carrying handle is wrapped in soft rubber and is fixedly connected to the top shell of the housing 1. When encountering narrow passages or terrain that is inconvenient to push, the operator can directly lift the device through the carrying handle, forming a complementary movement method with the pull rod 11 and the roller 12.

[0033] In actual outdoor work scenarios, operators can choose the appropriate mode of movement based on the terrain: in open and flat areas, extending the lever 11 and pushing the housing 1 allows the wheels 12 to roll smoothly, significantly saving physical effort in transporting the device; in narrow or rugged sections, the lever 11 can be retracted, and the device can be moved by carrying it using the handle; upon reaching the calibration location, locking the wheels 12 provides a stable place for subsequent operations. This optimized design further enhances the device's portability, allowing it to better adapt to the transportation needs of different outdoor environments, reducing the burden on operators, and helping to improve the efficiency of on-site calibration work.

[0034] This invention also provides a soil moisture sensor calibration method, applicable to any of the devices described in the above embodiments, the method comprising the following steps: S1. Collect on-site soil samples using a soil sampler and place the soil samples into the corresponding soil sample container; S2. Obtain the initial weight data of the soil sample container; S3. The soil sample in the sample container is heated by the heating module, and the real-time weight data of the sample container is continuously collected. S4. Determine that the soil sample drying is complete based on real-time weight data, obtain the corresponding dried weight data, and calculate the actual moisture content of the soil sample based on the initial weight data and the dried weight data. S5. Simultaneously acquire the measurement readings of the soil moisture sensor to be calibrated; S6. Establish the correspondence between the measured readings and the actual moisture content, and complete the calibration of the soil moisture sensor.

[0035] Specifically, the process begins with on-site soil sampling and sample loading. After arriving at the target calibration area with the equipment, the operator retrieves the soil sampler to collect undisturbed soil samples. Soil samples are then drilled at two points symmetrical to the center of the soil moisture sensor, at the same depth (the same depth as the sensor itself), to obtain representative soil samples for the sensor location. Furthermore, after sampling each layer of soil, sampling proceeds to the next layer. This method allows for the simultaneous drying and measurement of multiple soil samples (see reference). Figure 1 It can measure four types of soil samples simultaneously. During the sampling process, ensure that the soil samples are not contaminated by external moisture. Then, carefully place the collected soil samples into the sample container. After the samples are placed, place the sample container steadily on the weighing sensor inside the drying oven to ensure stable contact between the sample container and the weighing sensor, and avoid deviations in subsequent weight collection.

[0036] Next, the initial weight data of the soil sample container containing the soil sample is obtained (the weight data measured by the weighing sensor in this embodiment of the invention may include initial weight data, real-time weight data, etc., i.e., weight data is a general concept). The device is started through the operation panel, and the data acquisition and processing module establishes a data transmission connection with the weighing sensor. The weighing sensor measures the weight of the soil sample container and the soil sample inside, and transmits the measured initial weight data to the data acquisition and processing module. The data acquisition and processing module temporarily stores the initial weight data, and the initial weight data can be viewed through the operation panel to see if the initial weight data has been successfully acquired.

[0037] The heating and real-time weight acquisition process is then initiated. The acquisition and processing module sends a start command to the heating module, which begins operation and heats the soil sample inside the sample container. This design employs temperature measurement and heating without isolation, allowing the heat generated by the heating module to directly affect the soil sample. Simultaneously, the temperature sensor detects the temperature of the heating area and transmits the data to the acquisition and processing module, facilitating real-time monitoring of the heating status. During the heating process, the acquisition and processing module controls the weighing sensor to continuously acquire real-time weight data of the sample container and the soil sample inside. All real-time weight data is transmitted to the acquisition and processing module for temporary storage, making the weight change process traceable.

[0038] Then, based on the real-time weight data, it is determined that the soil sample has been dried and the actual moisture content is calculated. The acquisition and processing module analyzes the continuously acquired real-time weight data to determine whether the soil sample weight has stopped changing. When it is determined that the soil sample has been dried, the acquisition and processing module records the corresponding drying weight data at this time, and then calculates the actual moisture content of the soil sample based on the previously stored initial weight data and the drying weight data.

[0039] During the heating, drying, and weight acquisition process described above, the measurement readings of the soil moisture sensor to be calibrated are acquired simultaneously. The soil moisture sensor to be calibrated is placed in a suitable position close to the soil sample container so that the soil moisture sensor can accurately sense the moisture-related environment around the soil sample. The soil moisture sensor to be calibrated establishes a data connection with the acquisition and processing module and transmits the measured readings to the acquisition and processing module in real time. The acquisition and processing module associates and temporarily stores the measured readings with the weight data and actual moisture content data of the corresponding time period.

[0040] Finally, the correspondence between the measured readings and the actual moisture content is established to complete the calibration. The data acquisition and processing module organizes the temporarily stored measured readings of the soil moisture sensor to be calibrated and the calculated actual moisture content data, and establishes the correspondence between the two. After the correspondence is established, the calibration of the soil moisture sensor is completed. The calibration-related data can be exported and stored through the data interface for easy review and verification later.

[0041] The entire process is based on the integrated structure design of the device, requiring no additional equipment. The operation steps are simple and suitable for outdoor field calibration needs. At the same time, the cooperation of various components enables automatic data acquisition and processing, reducing errors caused by manual operation and ensuring the reliability of calibration results.

[0042] In some implementations, the completion of soil sample drying is determined based on real-time weight data, specifically including: Two consecutive sets of real-time weight data are continuously selected, and the difference between the two sets of real-time weight data is calculated. Determine whether the difference value is within the preset stability range. The preset stability range is used to characterize that the weight of the soil sample no longer changes. If the difference value is within the preset stable range, the soil sample drying is considered complete.

[0043] While the heating module heats the soil sample and the weighing sensor continuously collects real-time weight data, the acquisition and processing module simultaneously receives and temporarily stores all real-time weight data. Subsequently, the acquisition and processing module continuously selects two consecutive sets of real-time weight data from the temporarily stored data and calculates the difference between these two sets of adjacent data.

[0044] After the calculation is completed, the acquisition and processing module calls the preset stability range parameter and compares the above difference value with the preset stability range. The preset stability range is used to determine whether the weight of the soil sample has stopped changing. If the comparison result shows that the difference value is within the preset stability range, it is determined that the soil sample has been dried. The acquisition and processing module then records the corresponding dried weight data and executes the subsequent steps of calculating the actual moisture content based on the initial weight data and the dried weight data. If the difference value is not within the preset stability range, the acquisition and processing module continues to maintain the operation of the heating module and controls the weighing sensor to continuously collect real-time weight data, repeating the above difference value calculation and comparison process until the difference value meets the preset stability range requirements.

[0045] This method can ensure the timeliness and accuracy of the drying completion judgment, and is also suitable for the simple operation requirements of outdoor on-site calibration.

[0046] In some implementations, the difference between two sets of adjacent real-time weight data is determined by calculating the relative rate of change of the two sets of adjacent real-time weight data. The formula for calculating the relative rate of change is: in, For the first Next and first The relative rate of change of the next real-time weight data; For the first Real-time weight data collected in this instance; For the first Real-time weight data collected in this instance; Indicates taking the first Next and first The larger value in the next real-time weight data; The preset stability range is the relative rate of change. The preset rate of change threshold is met; this threshold characterizes that the weight of the soil sample no longer changes. When the preset rate of change threshold is reached, the difference value is determined to be within the preset stable range.

[0047] While the heating module continuously heats (e.g., at 105℃) and the weighing sensor continuously collects real-time weight data, the data acquisition and processing module continuously receives and temporarily stores the real-time weight data at each moment. Then, it sequentially extracts two consecutive sets of adjacent real-time weight data from the stored data and calculates the difference between the two sets of data using a preset relative change rate calculation formula. During the calculation, the acquisition and processing module uses the larger value from the two sets of adjacent data as the denominator and the difference between the two sets of data as the numerator, substituting them into the formula to obtain the corresponding relative change rate, which serves as a specific indicator characterizing the weight difference.

[0048] The preset stability range is specifically defined as the relative rate of change reaching a preset rate of change threshold. This preset rate of change threshold is used to clearly determine the standard for determining that the weight of the soil sample will no longer change. The acquisition and processing module compares the calculated relative rate of change with the preset rate of change threshold. If the relative rate of change meets the preset rate of change threshold requirement, that is, the difference value is determined to be within the preset stability range, the soil sample drying is completed (that is, the soil moisture content is essentially determined to be "0"), and the acquisition and processing module immediately records the dried weight data and triggers the subsequent moisture content calculation step; if the relative rate of change does not meet the preset rate of change threshold, the acquisition and processing module continues to control the operation of the heating module and the data acquisition of the weighing sensor, repeating the above relative rate of change calculation and comparison process.

[0049] The entire process requires no manual calculation or judgment, which makes the calculation of difference values ​​more standardized and accurate, thereby improving the accuracy of the judgment of drying completion and ensuring the reliability of subsequent actual moisture content calculation. It is suitable for outdoor on-site calibration to meet the needs of ease of operation and result stability.

[0050] To further improve the accuracy of drying completion judgment, a supplementary judgment based on the temperature data of the heating area collected by the existing temperature sensors of the device can be considered. Specifically, when the relative change rate reaches a preset change rate threshold, drying is not directly determined to be complete. Instead, multiple sets of continuous temperature data of the heating area collected by the temperature sensors are retrieved simultaneously, and the fluctuation range of the temperature data is calculated. Only when the temperature fluctuation range is within the preset stable temperature range, and the relative change rate remains stable within the threshold range for a preset duration, is the soil sample finally determined to be dried. This dual data verification method can effectively avoid misjudgment due to the relative change rate temporarily reaching the standard but the overall drying has not been achieved because of rapid evaporation of local soil moisture. At the same time, it makes full use of the existing components of the device, without the need for additional hardware structures. It can be achieved simply by optimizing the data processing logic of the acquisition and processing module, further improving the reliability of the calibration data.

[0051] In some implementations, the method further includes: The ambient temperature and the temperature of the heated area around the soil sample container were monitored while the soil sample was being heated. Determine whether the temperature of the heating zone meets the preset drying temperature and whether the ambient temperature is within the preset ambient temperature compensation range. If the temperature of the heating zone meets the preset drying temperature and the ambient temperature is within the preset ambient temperature compensation range, then temperature compensation is performed on the real-time weight data and the measurement readings of the soil moisture sensor to be calibrated based on the monitored ambient temperature. The real-time weight data after temperature compensation correction was used to determine the completion of soil sample drying and to calculate the actual moisture content. The measurement readings after temperature compensation correction were used to establish the correspondence between the actual moisture content and the actual moisture content.

[0052] Based on the overall process of the aforementioned calibration method, this implementation method improves the accuracy of the calibration data by adding a temperature monitoring and compensation step. The specific implementation process is as follows: During the heating process of the soil sample by the heating module, temperature sensors can be activated simultaneously to continuously collect data on the ambient temperature around the device and the temperature of the heated area around the soil sample container. The collected temperature data is transmitted in real time to the data acquisition and processing module for temporary storage. The data acquisition and processing module calls preset parameters, first determining whether the temperature of the heated area meets the preset drying temperature to ensure the heating module is in a stable operating state. Simultaneously, it determines whether the ambient temperature is within the preset ambient temperature compensation range. This range defines the environmental conditions requiring temperature compensation, preventing excessive ambient temperature fluctuations from interfering with calibration data.

[0053] If both temperature criteria are met—that is, the heating zone temperature is within the acceptable range and the ambient temperature is within the compensation range—the data acquisition and processing module performs temperature compensation correction on the synchronously acquired real-time weight data and the measurement readings of the soil moisture sensor to be calibrated, based on the temporarily stored ambient temperature data. Specifically, the acquisition and processing module can have a built-in preset temperature-weight correction coefficient table. It matches the corresponding correction coefficient to the real-time ambient temperature and multiplies this coefficient by the real-time weight data acquired by the weighing sensor to offset the impact of ambient temperature changes on weighing accuracy. For the measurement readings of the soil moisture sensor to be calibrated, the acquisition and processing module simultaneously retrieves a preset temperature-sensor reading correction model, substitutes the ambient temperature value into the correction model to calculate the corrected reading value, and then performs a difference calculation between the sensor's original measurement reading and the corrected reading to complete the temperature compensation correction of the measurement readings. The correction process is completed by the data acquisition and processing module without manual intervention. The corrected real-time weight data will be used to determine the completion of soil sample drying and to calculate the actual moisture content. The corrected measurement readings will be used to establish the correspondence between the actual moisture content and the actual moisture content. If any temperature judgment does not meet the requirements, the data acquisition and processing module will continue to monitor the temperature data and maintain the operation of the heating module until both temperature conditions are met, and then execute temperature compensation and subsequent processes.

[0054] By monitoring and correcting the data in real time, the impact of fluctuations in ambient temperature and heating status on the calibration data is effectively reduced, further improving the reliability of the calibration results while maintaining the ease of on-site operation.

[0055] In some implementations, the method further includes: Obtain information on the type of soil moisture sensor to be calibrated and the characteristics of the soil sample; Adjust the acquisition parameters for the measurement readings based on the sensor type information; Based on soil characteristic information, adjust the heating power of the heating module and the preset threshold of the relative change rate. Based on the adjusted acquisition parameters, heating power, and preset change rate threshold, the soil sample is heated, weight data is collected, drying is determined, and calibration is performed.

[0056] Based on the aforementioned calibration method's process for determining drying completion and data acquisition, this implementation method adapts to the differences in characteristics of different types of sensors and soil samples by specifically adjusting key parameters. The specific implementation process is as follows: Before starting the calibration operation, the operator first obtains the type information of the soil moisture sensor to be calibrated. This can be done by manually inputting key information such as the sensor model and measurement principle through the operation panel, or by connecting the soil moisture sensor to the acquisition and processing module through the device's data interface, allowing the acquisition and processing module to identify the sensor type. At the same time, the characteristic information of the soil sample, including soil texture and looseness, is determined through on-site observation or simple testing.

[0057] After receiving the above two types of information, the acquisition and processing module retrieves the built-in parameter matching library. Based on the sensor type information, it adjusts the acquisition parameters for the measurement readings accordingly. For example, for soil moisture sensors with different signal output types, it adjusts the data sampling frequency, signal amplification factor, or data filtering parameters to ensure clear and stable measurement readings and avoid reading distortion caused by sensor type mismatch. Based on the characteristics of the soil sample, it adjusts the heating power of the heating module. For example, for heavy, high-moisture soils, it appropriately increases the heating power to improve drying efficiency, while for loose, low-moisture soils, it reduces the heating power to avoid localized overheating. Simultaneously, it adjusts the preset threshold for the relative rate of change to adapt to the differences in soil moisture evaporation rates, improving the accuracy of determining drying completion.

[0058] After the parameters are adjusted, the data acquisition and processing module controls the heating module to start heating and the weighing sensor to continuously collect weight data according to the adjusted acquisition parameters, heating power and preset rate of change threshold. Subsequent steps such as determining the completion of drying, calculating the actual moisture content and establishing the correspondence between measurement readings and moisture content are all executed based on the adjusted parameters.

[0059] This solution not only improves the adaptability of the device to different scenarios and types of calibration requirements, but also reduces calibration errors caused by differences in sensor or soil characteristics through parameter matching, further ensuring the reliability of calibration results under different working conditions.

[0060] In some implementations, the method further includes: Each group of soil moisture sensors to be calibrated is assigned a unique calibration identifier, which is associated with the sampling depth and sampling location information of the corresponding soil sample. For the same soil moisture sensor to be calibrated, repeat the calibration steps to obtain multiple sets of calibration data; Calculate the deviation between the actual moisture content and the measured reading in multiple sets of calibration data, and determine whether the deviation is within the preset repeatability range; If the deviation value is within the preset repeatability range, multiple sets of calibration data are integrated to generate the final calibration curve; if the deviation value is not within the preset repeatability range, the data is resampled and calibrated.

[0061] Based on the aforementioned calibration method, this implementation method improves the stability and reliability of the calibration results by verifying and integrating multiple sets of calibration data. The specific implementation process is as follows: Before initiating calibration for a specific soil moisture sensor, a unique calibration identifier is assigned to the sensor via the data acquisition and processing module. Operators can manually input information such as the sampling depth and location corresponding to the sensor into the data acquisition and processing module through the control panel, binding this information to the calibration identifier. If the device has a positioning function, the data acquisition and processing module can also obtain the on-site location information and complete the association, ensuring that each set of calibration data can be traced back to the corresponding soil sample source.

[0062] After completing the initial calibration process, without changing the core calibration parameters, operators re-collect soil samples from the same area and depth using a soil sampler. After placing the samples in a sample container, the aforementioned complete calibration steps—heating, weight collection, moisture content calculation, and sensor reading acquisition—are repeated to obtain a second set of calibration data. Depending on actual needs, the above operations can be repeated multiple times to obtain multiple sets of calibration data. All sets of calibration data are temporarily categorized and stored by the acquisition and processing module, which binds them to corresponding calibration identifiers.

[0063] After multiple sets of data are collected, the acquisition and processing module analyzes all data under the same calibration identifier, extracts the correspondence between the actual moisture content and the sensor readings in each set of data, and calculates the deviation between the correspondences of different sets. Subsequently, the acquisition and processing module calls the preset repeatability range parameter and compares the calculated deviation with this range. If the deviation is within the preset repeatability range, it indicates good consistency among the multiple calibration results, and the acquisition and processing module can integrate the data from all sets to generate a more reliable final calibration curve. If the deviation exceeds the preset range, it indicates that there may be sample collection deviation or environmental interference during the calibration process. The acquisition and processing module can prompt the operator through the operation panel, requiring the sample to be collected again using the soil sampler and the complete calibration process to be repeated.

[0064] This implementation method effectively reduces the random errors that may exist in a single calibration by repeatedly verifying and integrating multiple sets of data, thereby improving the reliability and persuasiveness of the calibration results.

[0065] In some embodiments, after the soil sample is placed into the sample container in step S1, the method further includes: Three initial weight data were collected after the soil samples were left to stand for a preset time. Calculate the discrete values ​​of the three initial weight data and determine whether the discrete values ​​are within the preset weight stability range; If the discrete value is not within the preset weight stability range, it is determined that the soil sample is unevenly packed. The soil sample in the soil sample container is leveled and the initial weight data is collected 3 times. If the discrete value is within the preset weight stability range, the heating module is used to heat the soil sample at a preset power for a preset time to remove the floating water attached to the surface of the soil sample. After completing the step of removing floating water, proceed to the step of obtaining the initial weight data of the soil sample container.

[0066] In the aforementioned calibration method, during the step of loading soil samples into the sample container, this embodiment adds a pretreatment process after loading to ensure the accuracy of the initial weight data and the stability of the subsequent drying process. The specific implementation process is as follows: After the collected soil samples are placed into the sample container, the container is first placed stably on the weighing sensor and left to stand for a preset time to allow the soil samples to settle naturally, avoiding any loosening or gaps that may affect the accuracy of the weight acquisition. After the settling period, the acquisition and processing module controls the weighing sensor to continuously acquire initial weight data three times. All data is transmitted to the acquisition and processing module in real time and temporarily stored.

[0067] The data acquisition and processing module calculates the discrete values ​​between the three temporarily stored initial weight data points. It then calls a preset weight stability range parameter and compares the discrete values ​​with this range. If the discrete values ​​are not within the preset weight stability range, the soil sample is considered unevenly packed. The operator must level the soil sample in the container to eliminate voids or uneven packing. After this process, the container is placed back on the weighing sensor, and the process returns to the static setting step, acquiring the initial weight data three more times until the discrete values ​​meet the stability range requirements. If the discrete values ​​are within the preset weight stability range, the process proceeds to the surface water pretreatment stage.

[0068] During preprocessing, the acquisition and processing module controls the heating module to start at a preset low power for a preset duration. This power and duration setting avoids high temperatures damaging the soil sample's inherent properties while effectively removing surface water. After the surface water is removed, the heating module stops operating, and the acquisition and processing module again controls the weighing sensor to collect the initial weight data of the soil sample container. This data is used as the baseline initial weight for subsequent calibration calculations, which then connects to the subsequent calibration process, including obtaining the initial weight and starting heating.

[0069] This implementation method ensures the uniformity of soil heating by checking the weight dispersion value and ensures the authenticity of the initial weight data by removing floating water through low-power heating, effectively avoiding calibration errors caused by uneven sample loading and surface floating water.

[0070] The above description is merely a preferred embodiment and the technical principles employed in this application. This application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application.

Claims

1. A portable soil moisture sensor calibration device, characterized in that, It includes a housing (1), a soil drying module (2), a soil sampler (3), a collection and processing module (4), a heating module (5), and a power module (6). The soil drying module (2), the soil sampler (3), the collection and processing module (4), the heating module (5), and the power module (6) are all assembled inside the housing (1). The soil drying module (2) includes a drying box (21), a weighing sensor (22), and a soil sample container (23). The weighing sensor (22) is located inside the drying box (21), and the soil sample container (23) is supported on the weighing sensor (22). The heating module (5) corresponds to the soil sample container (23) and is used to heat the soil sample inside the soil sample container (23). The data acquisition and processing module (4) is electrically connected to the weighing sensor (22) and the heating module (5) respectively, and is used to acquire the weight data measured by the weighing sensor (22) and control the operation of the heating module (5); The power module (6) is electrically connected to the soil drying module (2), the data acquisition and processing module (4), and the heating module (5), respectively; The soil sampler (3) is used to collect soil samples from the field and can put the collected soil samples into the soil sample container (23).

2. The apparatus according to claim 1, characterized in that, The drying box (21) of the soil sample drying module (2) is equipped with multiple independent soil sample containers (23), and each soil sample container (23) is supported on the corresponding weighing sensor (22). The heating module (5) includes multiple independent heating units (51), each of which corresponds to a soil sample container (23) and is used to independently heat the soil sample in the corresponding soil sample container (23). The drying box (21) is made of heat-insulating material and is used to isolate each of the sample soil containers (23).

3. The apparatus according to claim 1, characterized in that, A retractable pull rod (11) is provided on one side of the box (1), and multiple rollers (12) are installed on the bottom of the box (1).

4. A method for calibrating a soil moisture sensor, characterized in that, Applied to the apparatus of any one of claims 1-3, the method comprises the following steps: S1. Collect on-site soil samples using the soil sampler and load the soil samples into the corresponding soil sample container; S2. Obtain the initial weight data of the soil sample container containing the soil sample; S3. The soil sample in the soil sample container is heated by the heating module, and the real-time weight data of the soil sample container is continuously collected. S4. Based on the real-time weight data, determine that the soil sample has been dried, obtain the corresponding dried weight data, and calculate the actual moisture content of the soil sample based on the initial weight data and the dried weight data; S5. Simultaneously acquire the measurement readings of the soil moisture sensor to be calibrated; S6. Establish the correspondence between the measured readings and the actual moisture content, and complete the calibration of the soil moisture sensor.

5. The method according to claim 4, characterized in that, The step of determining that the soil sample has finished drying based on the real-time weight data specifically includes: Two consecutive sets of adjacent real-time weight data are continuously selected, and the difference between the two sets of adjacent real-time weight data is calculated. Determine whether the difference value is within a preset stability range, where the preset stability range is used to characterize that the weight of the soil sample no longer changes; If the difference value is within the preset stable range, then the soil sample drying is considered complete.

6. The method according to claim 5, characterized in that, In the process of calculating the difference between two sets of adjacent real-time weight data, the difference is determined by calculating the relative rate of change of the two sets of adjacent real-time weight data. The formula for calculating the relative rate of change is: in, For the first Next and first The relative rate of change of the real-time weight data; For the first The real-time weight data collected this time; For the first The real-time weight data collected this time; Indicates taking the first Next and first The larger value among the real-time weight data described below; The preset stability range is the relative rate of change. The preset rate of change threshold is met, which indicates that the weight of the soil sample no longer changes; when When the preset rate of change threshold is reached, the difference value is determined to be within the preset stable range.

7. The method according to claim 4, characterized in that, The method further includes: The ambient temperature and the temperature of the heated area around the soil sample container were monitored while the soil sample was being heated. Determine whether the temperature of the heating zone meets the preset drying temperature and whether the ambient temperature is within the preset ambient temperature compensation range. If the temperature of the heating zone meets the preset drying temperature and the ambient temperature is within the preset ambient temperature compensation range, then temperature compensation is performed on the real-time weight data and the measurement reading of the soil moisture sensor to be calibrated based on the monitored ambient temperature. The real-time weight data, after temperature compensation correction, is used to determine the completion of soil sample drying and to calculate the actual moisture content. The measured readings, after temperature compensation correction, are used to establish a correspondence between the measured readings and the actual moisture content.

8. The method according to claim 6, characterized in that, The method further includes: Obtain the type information of the soil moisture sensor to be calibrated and the characteristic information of the soil sample; Adjust the acquisition parameters of the measurement readings based on the sensor type information; Based on the soil characteristic information, adjust the heating power of the heating module and the preset change rate threshold of the relative change rate; The soil sample is heated according to the adjusted acquisition parameters, heating power, and preset rate of change threshold. Weight data is collected, drying is determined, and calibration is performed.

9. The method according to claim 4, characterized in that, The method further includes: Each group of soil moisture sensors to be calibrated is assigned a unique calibration identifier, which is associated with the sampling depth and sampling location information of the corresponding soil sample. For the same soil moisture sensor to be calibrated, repeat the calibration steps to obtain multiple sets of calibration data; Calculate the deviation value between the actual moisture content and the measured reading in multiple sets of calibration data, and determine whether the deviation value is within the preset repeatability accuracy range; If the deviation value is within the preset repeatability range, multiple sets of calibration data are integrated to generate the final calibration curve; if the deviation value is not within the preset repeatability range, the data is resampled and calibrated.

10. The method according to claim 4, characterized in that, After the soil sample is placed into the sample container in step S1, the process further includes: The initial weight data was collected three times after the soil sample was left to stand for a preset time. Calculate the discrete values ​​of the initial weight data three times, and determine whether the discrete values ​​are within a preset weight stability range; If the discrete value is not within the preset weight stability range, it is determined that the soil sample is unevenly packed. The soil sample in the soil sample container is leveled and the initial weight data is collected 3 times. If the discrete value is within the preset weight stability range, the soil sample is heated by the heating module at a preset power for a preset time to remove the floating water attached to the surface of the soil sample. After completing the step of removing floating water, the next step is to obtain the initial weight data of the soil sample container containing the soil sample.

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