Automatic irrigation system and automatic irrigation method

Abstract

The invention discloses an automatic irrigation system and an automatic irrigation method, and relates to the technical field of intelligent agricultural irrigation. The automatic irrigation system comprises a humidity detection device and an automatic irrigation vehicle, the humidity detection device comprises a plurality of detection rods, different numbers of detection rods are arranged according to crop differences of different cultivated lands, and each detection rod has a set coordinate and a unique number. The automatic irrigation vehicle comprises a control unit, an irrigation unit, a navigation unit and a driving unit, and the control unit stores coordinates and numbers of the detection rods and minimum humidity threshold values of different cultivated lands and receives real-time humidity values of the detection rods; the irrigation unit is used for irrigating the cultivated land with the humidity lower than the corresponding minimum humidity threshold value; the navigation unit provides navigation for the automatic irrigation vehicle and feeds back real-time positioning coordinates to the control unit, and the driving unit drives the automatic irrigation vehicle to move. The irrigation unit, the navigation unit and the driving unit are electrically connected with the control unit, and the control unit controls the driving unit and the irrigation unit to act.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of intelligent agricultural irrigation technology, in particular to an automatic irrigation system and an automatic irrigation method. BACKGROUND

[0002] Intelligent irrigation technology is particularly significant for liberating productive forces, improving water resource utilization efficiency and promoting fine management of agriculture, and is a research hotspot of current enterprises and research institutions.

[0003] Although many research results have been achieved in the field of intelligent irrigation, the existing automatic irrigation systems rely on field weather stations to obtain macro weather and soil data, which is difficult to accurately perceive and respond to subtle humidity differences in different areas inside the field, resulting in uneven irrigation. Some devices that use fixed-point monitoring and integrated irrigation achieve local precise control, but have poor mobility and low work efficiency, and are difficult to perform irrigation tasks on large areas of farmland. Although some track-type irrigation systems can cover a larger area, they have a long infrastructure construction period, high cost, and fixed layout, which lacks flexibility and is difficult to meet the differentiated needs of different crops. In summary, the existing irrigation systems are difficult to achieve efficient, precise and adaptive irrigation of differentiated humidity inside large areas of farmland at low cost. SUMMARY

[0004] The purpose of the present application is to provide an automatic irrigation system and an automatic irrigation method to achieve accurate detection of field humidity while improving irrigation efficiency and precision, and at a relatively low cost.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] An automatic irrigation system comprises:

[0007] A humidity detection device comprising a plurality of detection rods, different numbers of detection rods being arranged according to the differences in crops of different fields, each detection rod having a set coordinate and a unique number;

[0008] An automatic irrigation vehicle comprising a control unit, an irrigation unit, a navigation unit and a driving unit, the control unit storing the coordinates and numbers of the detection rods, and the minimum humidity thresholds of different fields, and receiving real-time humidity values and numbers of the detection rods through wireless signals; the irrigation unit is used for irrigating the fields with humidity lower than the corresponding minimum humidity threshold; the navigation unit is used for providing navigation for the automatic irrigation vehicle and feeding back real-time positioning coordinates to the control unit, and the driving unit is used for driving the wheel body of the automatic irrigation vehicle to move;

[0009] The irrigation unit, the navigation unit and the driving unit are electrically connected with the control unit, and the control unit controls the driving unit and the irrigation unit to act according to the real-time positioning coordinates and the real-time humidity value.

[0010] As an optional solution of the automatic irrigation system, the humidity detection device further comprises a first wireless transmission member, the detection rod comprises a telescopic rod and a humidity sensor, the humidity sensor is arranged at one end of the telescopic rod and inserted into the soil, and the first wireless transmission member is arranged at the other end of the telescopic rod and located on the ground, and the first wireless transmission member is in communication connection with the control unit.

[0011] As an optional solution of the automatic irrigation system, the irrigation unit comprises an irrigation pump, a water storage tank and a spray head assembly, the spray head assembly is connected with the water storage tank through the irrigation pump, the irrigation pump is electrically connected with the control unit and controlled to open and close by the control unit.

[0012] The water storage tank is provided with a water level sensor, the water level sensor is in communication connection with the control unit, when the control unit receives a water shortage signal sent by the water level sensor, the control unit controls the irrigation pump to be closed, records the current coordinates, and controls the automatic irrigation vehicle to return to the water replenishing point to replenish water.

[0013] As an optional solution of the automatic irrigation system, the driving unit comprises four hub motors, each hub motor drives a wheel body; the control unit adjusts the rotating speed of the wheel body by controlling the torque of the hub motor.

[0014] As an optional solution of the automatic irrigation system, the automatic irrigation vehicle is provided with an emergency stop button and an opening button.

[0015] As an optional solution of the automatic irrigation system, the automatic irrigation system further comprises a power supply device, the power supply device comprises a first power supply and a second power supply, the first power supply is used for supplying power for the humidity detection device, and the second power supply is used for supplying power for the automatic irrigation vehicle.

[0016] As an optional solution of the automatic irrigation system, the automatic irrigation system further comprises a water replenishing point and a charging point, and the water replenishing point and the charging point are evenly distributed according to the farmland area.

[0017] As an optional solution of the automatic irrigation system, the automatic irrigation system is in communication connection with a terminal device.

[0018] An automatic irrigation method applied to the automatic irrigation system as in any one of the above solutions, the automatic irrigation method comprises the following steps:

[0019] The humidity detection device is arranged in the farmland, and the number, density and insertion depth of the detection rods are determined according to the differences of crops;

[0020] The control unit obtains the real-time humidity values and numbers of the detection rods in real time, and determines a plot with humidity lower than a corresponding minimum humidity threshold as a target plot according to a preset analysis model;

[0021] The control unit controls the driving unit to drive the automatic irrigation vehicle to reach the target plot under the guidance of the navigation unit, and then controls the driving unit to drive the automatic irrigation vehicle to circle the target plot while controlling the irrigation unit to irrigate.

[0022] As an optional solution of the automatic irrigation method, the step of determining the target plot according to the preset analysis model comprises:

[0023] The control unit stores the received real-time humidity values and numbers of the detection rods in a first data table;

[0024] The real-time humidity values in the first data table are polled, and a plot where a detection rod with a real-time humidity value less than a minimum humidity threshold of the plot is located is determined as a target plot.

[0025] As an optional solution of the automatic irrigation method, the irrigation unit comprises an irrigation pump and a water storage tank, the water storage tank is provided with a water level sensor, the automatic irrigation vehicle is provided with a second power supply, and the method for irrigating the target plot by the irrigation unit further comprises:

[0026] When the automatic irrigation vehicle travels to the target plot, the control unit controls the power and working time of the irrigation pump according to the required irrigation amount of the target plot, and controls the driving unit to drive the automatic irrigation vehicle to circle the target plot while controlling the irrigation unit to irrigate;

[0027] During the irrigation process, the control unit monitors the water level of the water storage tank and the power of the second power supply in real time;

[0028] If the remaining water amount of the water storage tank is insufficient or the power of the second power supply is insufficient, the control unit records the current coordinates and controls the automatic irrigation vehicle to travel to the nearest water replenishment point for water replenishment or charging point for charging;

[0029] After the water replenishment or charging is completed, the control unit controls the automatic irrigation vehicle to return to the recorded coordinates to continue irrigation;

[0030] Until all the target plots are irrigated, the control unit controls the automatic irrigation vehicle to return to the base station.

[0031] As an optional solution of the automatic irrigation method, the method for calculating the required irrigation amount of the target plot comprises:

[0032] The real-time humidity value and its number of the detection rod with a real-time humidity value less than the minimum humidity threshold of the plot where it is located are stored in a second data table;

[0033] The difference between the real-time humidity value and the corresponding minimum humidity threshold is calculated;

[0034] The required irrigation amount of the target plot is calculated according to the difference and recorded in the second data table.

[0035] As an optional solution of the automatic irrigation method, the control unit controls the power and working time of the irrigation pump according to the required irrigation amount recorded in the second data table;

[0036] After completing the irrigation of one target plot, the control unit deletes the data of the target plot from the second data table until all data are deleted.

[0037] As an optional solution of the automatic irrigation method, the driving unit comprises four in-wheel motors, each of which drives a wheel body, and the step of the control unit controlling the driving unit to drive the automatic irrigation vehicle to the target plot comprises:

[0038] The control unit plans a target path according to the positioning coordinates of the navigation unit and the coordinates of the target plot and sets the target rotating speed of each wheel body of the automatic irrigation vehicle;

[0039] The control unit controls the driving unit to drive each wheel body to travel at the target rotating speed and corrects the torque of each in-wheel motor according to the real-time positioning coordinates of the navigation unit and the actual rotating speed feedback of the wheel body.

[0040] As an optional solution of the automatic irrigation method, the method for correcting the torque of each in-wheel motor comprises:

[0041] By allocating different torques to the four wheel bodies, the automatic irrigation vehicle generates a yawing moment to adjust the driving angle;

[0042] A fuzzy control method is used to adjust the torque allocation of the four wheel bodies by taking the deviation between the real-time driving direction of the automatic irrigation vehicle and the target orientation as input.

[0043] As an optional solution of the automatic irrigation method, the step of adjusting the torque by using the fuzzy control method comprises:

[0044] The positioning coordinates of the navigation unit are processed to determine the nearest point of the current position of the automatic irrigation vehicle.

[0045] Setting a preview distance, and finding a path point closest to the preview distance along the target path as a preview point;

[0046] Calculating a desired turning angle at the preview point;

[0047] According to the desired turning angle and the actual turning angle of the automatic irrigation vehicle, a required turning angle adjustment amount is calculated by using a fuzzy control algorithm;

[0048] According to the turning angle adjustment amount and the parameters of the wheel body, the torque of each wheel hub motor is calculated.

[0049] The present application has the following advantages:

[0050] The automatic irrigation system provided by the present application constructs a distributed soil humidity monitoring network by arranging multiple detection rods with set coordinates and unique numbers in different farmlands according to crop differences. The control unit stores the coordinates of each detection rod and the corresponding minimum humidity threshold, so that the farmland in a water shortage state can be accurately identified, and the irrigation precision and water resource utilization rate are improved. The automatic irrigation vehicle integrates an irrigation unit, a navigation unit and a driving unit, and controls the driving unit and the irrigation unit to act through the control unit receiving real-time humidity values and real-time positioning coordinates, so that the automatic irrigation vehicle can move to any farmland in a water shortage state for irrigation by using the navigation unit and the driving unit. The entire irrigation process does not require manual intervention, and the farmland in a water shortage state can be adaptively found and the irrigation task can be actively completed, reducing the deployment cost and period of infrastructure, and the automated mobile irrigation greatly improves the operation efficiency.

[0051] The automatic irrigation method provided by the present application is applied to the above automatic irrigation system, adaptively configures humidity detection devices according to crop differences, receives and analyzes real-time humidity values of each detection rod in real time through a control unit, accurately identifies a target plot in a water shortage state, then controls an automatic irrigation vehicle to reach the target plot under the guidance of a navigation unit, and performs irrigation while circling the target plot. Thus, in the background of not needing fixed facilities, 24-hour monitoring of farmland humidity and flexible and accurate irrigation of large-area farmland are realized, the water resource utilization rate, irrigation precision and efficiency are improved, and the cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is a structural schematic diagram of the automatic irrigation vehicle provided by the first embodiment of the present application;

[0053] Figure 2 is a structural schematic diagram of the humidity detection device provided by the first embodiment of the present application;

[0054] Figure 3 is a flowchart of the automatic irrigation method provided by the second embodiment of the present application;

[0055] Figure 4 is a schematic diagram of the automatic irrigation vehicle provided by the second embodiment of the present application according to the coordinate control driving;

[0056] Figure 5 is a desired turning angle schematic diagram provided by the second embodiment of the present application;

[0057] Figure 6 is a two-degree-of-freedom schematic diagram of the automatic irrigation vehicle provided by the second embodiment of the present application.

[0058] In the figure:

[0059] 100, soil;

[0060] 1, humidity detection device; 11, telescopic rod; 12, humidity sensor; 13, first wireless transmission;

[0061] 2, automatic irrigation vehicle; 21, wheel hub motor; 22, water storage tank; 23, irrigation pump; 24, second wireless transmission; 25, navigation unit; 26, second power supply; 27, wheel body; 28, control unit; 281, vehicle controller; 282, irrigation controller; 283, drive controller;

[0062] 3, target path; 31, nearest point; 32, maximum distance point; 33, pre-look point. DETAILED DESCRIPTION

[0063] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0064] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0065] Unless otherwise defined, the terms "mounting", "connected", "connecting", "fixed", "fixing" should be construed as broadly, for example, can be fixed connection, can also be detachable connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0066] Unless otherwise expressly specified and limited, "on" or "under" of the first feature to the second feature can include that the first feature and the second feature are in direct contact, or the first feature and the second feature are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "above" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature "below", "below" and "below" of the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is less than the second feature in horizontal height.

[0067] The technical scheme of the present application will be further illustrated by specific embodiments in combination with the drawings.

[0068] Embodiment one:

[0069] As shown in Figure 1 and Figure 2 The present embodiment provides an automatic irrigation system, which comprises a humidity detection device 1 and an automatic irrigation vehicle 2, and the two cooperate to realize precision and automation irrigation of farmland.

[0070] The humidity detection device 1 comprises a plurality of detection rods, and different numbers of detection rods are arranged according to the differences of crops in different farmlands. Each detection rod has a set coordinate and a unique number. Because different crops have different requirements for soil 100 humidity, the number and density of detection rods are flexibly arranged according to the differences of crops, and the soil 100 humidity of different positions in different farmlands is monitored in real time. Moreover, the minimum humidity threshold value of different farmlands can be independently set, and when the humidity value detected by the detection rod is lower than the minimum humidity threshold value corresponding to the block where it is located, irrigation work can be performed on the block, so that different soil 100 humidity control can be realized for different crop farmlands.

[0071] The automatic irrigation vehicle 2 comprises a control unit 28, an irrigation unit, a navigation unit 25 and a driving unit. The control unit 28 stores the coordinates and numbers of the detection rods and the minimum humidity thresholds of different farmlands, and receives the real-time humidity values and numbers of the detection rods through wireless signals. The irrigation unit is used for irrigating the farmland with the humidity lower than the corresponding minimum humidity threshold. The navigation unit 25 is used for providing navigation for the automatic irrigation vehicle 2 and feeding back the real-time positioning coordinates to the control unit 28. The driving unit is used for driving the wheel body 27 of the automatic irrigation vehicle 2 to move. The irrigation unit, the navigation unit 25 and the driving unit are electrically connected with the control unit 28. The control unit 28 controls the driving unit and the irrigation unit to act according to the real-time positioning coordinates and the real-time humidity values.

[0072] The automatic irrigation system constructs a distributed soil 100 humidity monitoring network by arranging a plurality of detection rods with set coordinates and unique numbers on different farmlands according to the differences of crops. The control unit 28 stores the coordinates and corresponding minimum humidity thresholds of each detection rod, so as to accurately identify the farmland in water shortage state and improve the irrigation accuracy and water resource utilization rate. The automatic irrigation vehicle 2 integrates the irrigation unit, the navigation unit 25 and the driving unit, and controls the driving unit and the irrigation unit to act through the control unit 28 receiving the real-time humidity values and the real-time positioning coordinates. The automatic irrigation vehicle 2 can move to any farmland in water shortage state for irrigation by using the navigation unit 25 and the driving unit. The whole irrigation process does not need manual intervention, and the farmland in water shortage state can be adaptively found and the irrigation task can be actively completed, which reduces the deployment cost and period of infrastructure and greatly improves the operation efficiency of automatic mobile irrigation.

[0073] The control unit 28 comprises a vehicle controller 281, an irrigation controller 282 and a driving controller 283, which establish internal communication through a CAN bus. The vehicle controller 281 stores the coordinate information, numbers of the detection rods and the minimum humidity thresholds of different farmlands, and receives the real-time humidity data of each detection rod through wireless communication. The navigation unit 25 adopts a GPS or Beidou positioning system to provide real-time positioning coordinates for the vehicle.

[0074] In an embodiment, the humidity detection device 1 further comprises a first wireless transmission member 13. The detection rod comprises a telescopic rod 11 and a humidity sensor 12. The humidity sensor 12 is arranged at one end of the telescopic rod 11 and inserted into the soil 100. The first wireless transmission member 13 is arranged at the other end of the telescopic rod 11 and located on the ground. The first wireless transmission member 13 is in communication connection with the control unit 28. By adjusting the length of the telescopic rod 11, the monitoring depth requirement of different crop root systems can be adapted, so that more accurate humidity monitoring can be realized.

[0075] In an embodiment, the irrigation unit comprises an irrigation pump 23, a water storage tank 22, and a spray head assembly connected to the water storage tank 22 by the irrigation pump 23, the irrigation pump 23 is electrically connected to and controlled by the control unit 28. The irrigation pump 23 serves as a power source to control the water flow output. The arrangement of the spray head assembly ensures that the irrigation width covers the vehicle travel path. The water level sensor in the water storage tank 22 monitors the water level in real time. When the water level is below the set threshold, the irrigation controller 282 controls the irrigation pump 23 to shut down, the vehicle controller 281 records the current coordinates, and the automatic irrigation vehicle 2 returns to the nearest water replenishment point for water replenishment.

[0076] In an embodiment, the driving unit comprises four hub motors 21, each hub motor 21 drives a wheel body 27; the control unit 28 adjusts the speed of the wheel body 27 by controlling the torque of the hub motor 21. The driving controller 283 is electrically connected to the hub motor 21, and is used to control the torque of the hub motor 21, thereby adjusting the speed of the wheel body 27. The speed of the four wheel bodies 27 is controlled separately, and the output torque of each hub motor 21 is adjusted to achieve precise speed control and steering adjustment.

[0077] Exemplarily, the first wireless transmission member 13 and the second wireless transmission member 24 are both Bluetooth or WiFi wireless transmission modes. The first wireless transmission member 13 sends the humidity value detected by the humidity sensor 12 to the vehicle controller 281 in real time, the vehicle controller 281 is responsible for processing the return data of the first wireless transmission member 13 and making logical judgments, processing the data of the navigation unit 25 and issuing motion instructions to the driving controller 283, and determining whether the target plot has been reached according to the positioning coordinates of the navigation unit 25 to issue irrigation instructions to the irrigation unit, and processing the return data of the driving controller 283 and the irrigation controller 282 to complete the control loop.

[0078] In an embodiment, the automatic irrigation system further comprises a power supply device, the power supply device comprises a first power supply and a second power supply 26, the first power supply is used to supply power to the humidity detection device 1, and the second power supply 26 is used to supply power to the automatic irrigation vehicle 2. The first power supply supplies power to the first wireless transmission member 13, and the second power supply 26 supplies power to all electrical components on the automatic irrigation vehicle 2.

[0079] Exemplarily, the first power supply and the second power supply 26 are both storage batteries.

[0080] In an embodiment, the automatic irrigation system further comprises a water replenishment point and a charging point, which are evenly distributed according to the cultivated land area. The water replenishment point is used to replenish water for the water storage tank 22, and the charging point is used to supply power for the second power supply 26, thereby ensuring the continuity of the irrigation operation of the automatic irrigation vehicle 2 and improving the irrigation efficiency.

[0081] In an embodiment, the automatic irrigation vehicle 2 is provided with an emergency stop button and an opening button. The emergency stop button is used to stop all actions of the automatic irrigation vehicle 2, such as driving, irrigation, etc., and is generally used in emergency situations to avoid danger. The opening button is used for the opening operation of the automatic irrigation system. By pressing the opening button, the soil humidity value is monitored in real time and irrigation work is performed.

[0082] In an embodiment, the automatic irrigation system is in communication connection with a terminal device. The automatic irrigation system can be monitored through the APP on the terminal device, and the staff can monitor the information such as the humidity of the farmland, the working state of the automatic irrigation vehicle 2, the driving speed, the water quantity, the coordinates, etc. on the APP of the terminal device.

[0083] When the water quantity in the water storage tank 22 in the automatic irrigation vehicle 2 is insufficient, the automatic irrigation vehicle 2 automatically sends a prompt sound, and the APP also prompts that water needs to be added.

[0084] The automatic irrigation system is used for automatic irrigation of agricultural farmland. The humidity detection device 1 performs 24-hour real-time monitoring, and the automatic irrigation vehicle 2 can process humidity information in real time for 24 hours. The farmland below the corresponding humidity threshold value can be quickly responded to, and the target plot is reached for irrigation work. Based on the cooperation of the humidity detection device 1 and the automatic irrigation vehicle 2, 24-hour unmanned operation of farmland irrigation is realized, and high precision, high efficiency, low cost, flexible arrangement and high safety are achieved. In order to ensure the continuous operation of the system, water supply points and charging points are reasonably arranged in the farmland. The water supply point provides water supply, and the charging point charges the first power supply and the second power supply 26. The automatic irrigation vehicle 2 is provided with an emergency stop button and an opening button to ensure the safety of operation. At the same time, the system is connected with a terminal device through wireless communication, and supports remote monitoring of the working state, the position of the automatic irrigation vehicle 2 and the water quantity of the water storage tank 22 and other parameters.

[0085] Embodiment two:

[0086] As shown in Figure 3 The embodiment provides an automatic irrigation method applied to the automatic irrigation system provided in embodiment one, and the automatic irrigation method comprises the following steps:

[0087] S10, setting a humidity detection device in the farmland, and determining the number, density and insertion depth of the detection rods according to the differences of crops.

[0088] The arrangement scheme of the detection rods is differentiated according to the water demand characteristics of the crops. For crops with high water demand and high sensitivity to soil humidity (such as rice, vegetables, etc.), a higher detection rod arrangement density is used in the corresponding farmland, the number of monitoring points per unit area is increased, and the insertion depth of the detection rods is set deeper to comprehensively monitor the water conditions at different depths of the crop root zone. On the contrary, for crops with strong drought resistance and low water demand (such as sesame, sorghum, etc.), a lower arrangement density and a shallower insertion depth are used to optimize resource input while ensuring monitoring effectiveness.

[0089] S20, the control unit obtains the real-time humidity value and its number of each detection rod in real time, and determines the plot with humidity lower than the corresponding minimum humidity threshold as the target plot according to the preset analysis model.

[0090] Due to the large number of detection rods, the vehicle control unit needs to compare the real-time humidity values of multiple detection rods with their corresponding minimum humidity thresholds to determine the target plot that needs to be irrigated.

[0091] In an embodiment, the step of determining the target plot according to the preset analysis model includes: the control unit stores the received real-time humidity value and its number of each detection rod in a first data table. The real-time humidity values in the first data table are polled, and the plot where the detection rod with a real-time humidity value less than the minimum humidity threshold of the plot is determined as the target plot.

[0092] The vehicle control unit creates and maintains a dynamically updated first data table in its memory when it is running. The core fields of the first data table include at least: detection rod number, real-time humidity value, minimum humidity threshold corresponding to the number, and state identification bit. The vehicle control unit continuously receives data packets transmitted on the detection rods distributed in various places through the first wireless transmission component. After the data packets are parsed, the "number" and "real-time humidity value" therein are written as a new record in the first data table, and the previous data of the number is overwritten to ensure the real-time nature of the data. The program built-in the vehicle control unit polls the first data table at a fixed period (for example: every minute). For each record in the table, the program performs logical judgment: compares the "real-time humidity value" of the record with the "minimum humidity threshold" stored in advance. When the real-time humidity value of a record continuously falls below the corresponding minimum humidity threshold and reaches a preset stable time (for example: continuously for 3 periods), it is determined that the area where the detection rod is located is in a water shortage state. The system immediately determines the plot where the detection rod is located as the target plot, and adds it to the to-be-operated queue, and at the same time, the state identification bit of the plot in the first data table can be updated to "need irrigation".

[0093] S30, the control unit controls the driving unit to drive the automatic irrigation vehicle to reach the target plot under the guidance of the navigation unit, and then controls the driving unit to drive the automatic irrigation vehicle to circle the target plot while controlling the irrigation unit to irrigate.

[0094] In an embodiment, the method for the irrigation unit to irrigate the target plot further comprises:

[0095] After the automatic irrigation vehicle travels to the target plot, the control unit controls the power and working time of the irrigation pump according to the required irrigation amount of the target plot, and controls the driving unit to drive the automatic irrigation vehicle to circle the target plot while controlling the irrigation unit to irrigate. During the irrigation process, the control unit monitors the water level of the water storage tank and the power of the second power supply in real time. If the remaining water amount of the water storage tank is insufficient or the power of the second power supply is insufficient, the control unit records the current coordinates and controls the automatic irrigation vehicle to travel to the nearest water replenishment point for water replenishment or charging point for charging. After the water replenishment or charging is completed, the control unit controls the automatic irrigation vehicle to return to the recorded coordinates to continue irrigation. Until all target plots are irrigated, the control unit controls the automatic irrigation vehicle to return to the base station.

[0096] The vehicle controller calculates the required irrigation amount according to the area of the target plot, the type of crop, and the humidity difference, and then the system converts the required irrigation amount into a combination control of the power of the irrigation pump and the expected working time. For example, for light water shortage, a low-power, long-time mode can be used for infiltration irrigation; for severe water shortage, a high-power mode is used to quickly supplement water. The vehicle controller issues a path instruction to the driving controller to "circle the target plot". The navigation unit ensures that the automatic irrigation vehicle travels along the preset boundary through real-time positioning. During this process, the opening and closing of the irrigation unit are synchronized with the moving speed of the automatic irrigation vehicle, ensuring that the coverage range of the spray head assembly coincides with the travel trajectory, achieving uniform and non-missing irrigation of the target plot.

[0097] In an embodiment, when the automatic irrigation vehicle controls the irrigation unit to irrigate, the required irrigation amount of each target plot is calculated in sequence first, and then the automatic irrigation vehicle is controlled to irrigate the multiple target plots in sequence. Specifically, the following steps are included: storing the real-time humidity value and the number of the detection rod whose real-time humidity value is less than the minimum humidity threshold value of the plot where it is located in the second data table. Calculate the difference between the real-time humidity value and the corresponding minimum humidity threshold value. Calculate the required irrigation amount of the target plot according to the difference and record it in the second data table. The control unit controls the power and working time of the irrigation pump according to the required irrigation amount recorded in the second data table. After completing the irrigation of one target plot, the control unit deletes the data of the target plot from the second data table, until all data are deleted.

[0098] During the irrigation process, the whole vehicle controller monitors the water level of the water storage tank and the remaining power of the second power supply through the water level sensor and the management system of the first power supply at a fixed cycle (such as every 10 seconds). The system presets a safety threshold (such as water < 15% or power < 20%). When either condition triggers, the whole vehicle controller immediately generates an interrupt instruction. The instruction accurately records the coordinates of the current interrupt point and saves it to the non-volatile memory to prevent data loss.

[0099] The whole vehicle controller plans the optimal path to reach the nearest water replenishment point or charging point according to the stored map of the water replenishment point and the charging point, and automatically goes to it. After completing the replenishment, the system automatically retrieves the task information before the interruption from the stored start point, automatically returns the automatic irrigation vehicle to the recorded coordinate point, and continues to perform the irrigation task from the working state at the time of interruption (such as the remaining irrigation amount, the unfinished path).

[0100] The system maintains a dynamically updated "target plot task queue", and removes each completed target plot irrigation from the queue. When the system detects that the task queue is empty, it is judged that "all target plots have been irrigated". Subsequently, the whole vehicle controller plans the return path to drive the automatic irrigation vehicle to automatically return to the base station (such as the garage or parking point) and enter the standby state, completing the entire operation cycle.

[0101] Specifically, the step of the control unit controlling the driving unit to drive the automatic irrigation vehicle to reach the target plot includes: the control unit planning a target path according to the positioning coordinates of the navigation unit and the coordinates of the target plot, and setting the target rotating speed of each wheel body of the automatic irrigation vehicle. The control unit controls the driving unit to drive each wheel body to travel at the target rotating speed, and corrects the torque of each wheel hub motor according to the real-time positioning coordinates of the navigation unit and the actual rotating speed feedback of the wheel body.

[0102] The whole vehicle controller makes global path planning in the pre-stored map data according to the real-time positioning coordinates (point A) provided by the navigation unit and the entrance coordinates (point B) of the target plot. The planning not only considers the shortest distance between the two points, but also avoids known fixed obstacles (such as ditches, fixed facilities) to generate a globally referenced path. Then, according to the global path, the kinematic model of the vehicle and the set safe driving speed, the target rotation speed required by the four wheel bodies in the future control cycle is calculated. If steering is required, the system will assign different target rotation speeds to the inner and outer wheel bodies to form a differential. The system collects two key feedbacks in real time: one is the higher precision real-time pose (including coordinates and heading angle) provided by the navigation unit; the other is the actual rotation speed of each wheel body fed back by the encoder installed on the wheel hub motor. The whole vehicle controller compares the actual pose with the target path to calculate the lateral position deviation and the heading angle deviation; at the same time, it compares the actual rotation speed of the wheel body with the target rotation speed to calculate the rotation speed deviation. Then, the PID controller calculates and corrects the torque command output to each wheel hub motor in real time according to these comprehensive deviations. For example, when the automatic irrigation vehicle deviates from the predetermined path due to ground slippage, the navigation unit will sense the lateral deviation. The drive controller will then increase the torque of a certain side wheel body to generate a corrective yaw moment, pulling the automatic irrigation vehicle back to the correct route. Similarly, when the actual rotation speed of a certain wheel body is lower than the target rotation speed, the system will instantaneously increase the torque of the wheel hub motor of the wheel body to ensure that the rotation speed is synchronized. High-precision path tracking in the farmland environment is achieved, ensuring the work efficiency; the terrain adaptability and driving stability of the automatic irrigation vehicle are improved, ensuring the reliability under complex working conditions.

[0103] In an embodiment, the method of correcting the torque of each wheel hub motor includes making the automatic irrigation vehicle generate a yaw moment to adjust the driving angle by assigning different torques to the four wheel bodies. The fuzzy control method is used to adjust the torque distribution of the four wheel bodies with the deviation between the real-time driving direction of the automatic irrigation vehicle and the target orientation as the input. The system has a built-in "fuzzy rule base" based on expert experience, which is composed of a series of conditional rules in the form of "IF-THEN" to describe how to adjust the torque distribution according to the input deviation state. The fuzzy inference engine activates and calculates all related rules according to the current input value to comprehensively obtain a fuzzy output set of the expected torque adjustment amount of the four wheel bodies. Finally, through the "defuzzification" process (such as the center of gravity method), the fuzzy torque adjustment amount set is converted back to an accurate torque control value. The torque control value is sent to the drive controller of the wheel hub motor to realize the real-time differentiated distribution of the left and right side wheel body torques, thereby generating an accurate yaw moment to actively and smoothly correct the driving direction of the automatic irrigation vehicle and make it stably track the target path.

[0104] Exemplarily, the embodiment designs a single-point preview calculation algorithm capable of being applied to a large-curvature path, which can guide the automatic irrigation vehicle to track in a large-curvature curve under the advantages of ensuring the real-time of the single-point preview; meanwhile, the embodiment further researches the variable universe FSMC on the basis of the fuzzy sliding mode control, aiming to realize the more rapid control and more accurate response of the lateral control in the complex terrain under the premise of eliminating the chattering phenomenon.

[0105] Specifically, the step of adjusting the torque by using the fuzzy control method comprises:

[0106] Firstly, the positioning coordinates of the navigation unit are processed to determine the nearest point 31 of the current position of the automatic irrigation vehicle.

[0107] Whether the input is artificial or collected in advance, the final obtained planning path information is a series of GPS longitude and latitude coordinate points, so it is necessary to first convert these longitude and latitude coordinates (lon, lat) to obtain discrete coordinate points (X, Y) in the geodetic coordinate system:

[0108] ,

[0109] Among them , , N is the curvature radius of the quadrant of the circle, and the value of ζ is obtained by the following formula:

[0110] .

[0111] Through the coordinate system after the Gauss projection, the positive direction of the x-axis corresponds to the north, and the positive direction of the y-axis corresponds to the south. Then, the geodetic coordinate system is converted into the vehicle coordinate system (X, Y):

[0112] ,

[0113] Among them, the vehicle heading angle is After the coordinate conversion is completed, the selection of the preview point 33 can be performed.

[0114] As shown in Figure 4 , the embodiment adopts a single-point preview method considering the curvature to calculate the preview point 33, and the determination method of the preselected preview point 33 is as follows:

[0115] According to the GPS information of the target path 3, the nearest point 31 of the current position of the automatic irrigation vehicle is determined after the coordinate conversion, and the following formula is obtained after simplifying and operating according to formula (1). The nearest point 31 is found by using the following formula:

[0116] ,

[0117] Among them and latitude and longitude coordinates of the path point, and latitude and longitude coordinates of the automatic irrigation vehicle. Get and then calculate the distance between the discrete points on the expected path and the automatic irrigation vehicle.

[0118] Then set the preview distance, and find the path point closest to the preview distance along the target path 3 as the preview point 33.

[0119] The preview distance is determined according to the following formula:

[0120] ,

[0121] where is the vehicle speed, is the proportional coefficient, is the minimum preview distance.

[0122] From the nearest point 31, the distance between the points on the path and the automatic irrigation vehicle is calculated in turn, and the path point closest to the preview distance is taken as the preview point 33, and the point coordinates are returned, thus obtaining the pre-selected preview point 33.

[0123] After obtaining the pre-selected preview point 33, the curvature of the current path is reflected by finding the maximum distance point 32, and when the curvature is too large, the previous preview point 33 is discarded and reselected.

[0124] After determining the preview point 33, the line connecting the current position of the automatic irrigation vehicle and the preview point 33 is calculated; all points in the nearest point 31 and the preview point 33 are traversed, and the distance between these points and the line is calculated, and thus the maximum distance point 32 is determined. The distance between the maximum distance point 32 and the line is judged whether it exceeds the threshold value , and thus whether the pre-selected preview point 33 is reasonable. The value of the curvature does not need to be calculated specifically, and the size of the curvature is reflected indirectly by judging the distance between the maximum distance point 32 and the line. If it is judged that it exceeds the threshold value, the current maximum distance point 32 is selected as the pre-selected preview point 33, and the above steps are continuously performed until the requirements are met, and then the pre-selected preview point is output as the preview point 33.

[0125] The expected turning angle at the preview point 33 is calculated.

[0126] As shown in Figure 5 , in the geodetic coordinate system, let the coordinate of the center point of the rear axle of the automatic irrigation vehicle be , the coordinate of the preview point 33 (i.e. the target point) be , the turning angle of the front wheel of the automatic irrigation vehicle be , and the turning radius at the current time be ​According to the principle of plane geometry, it is obtained that:

[0127] ,

[0128] In the formula, represents the distance between the rear axle center point and the preview point 33, that is, the preview distance; is the included angle between the heading direction of the automatic irrigation vehicle and the preview line, and its value can be solved by using the following formula:

[0129] ,

[0130] In the formula, is the heading angle of the automatic irrigation vehicle. According to the Ackerman steering principle, it is obtained that:

[0131] ,

[0132] Among them, represents the wheelbase of the automatic irrigation vehicle.

[0133] Substituting formulas (5) and (6) into formula (7), it is obtained that:

[0134] ,

[0135] By converting the form of formula (8), the control law of the pure tracking controller can be obtained:

[0136] .

[0137] Then, according to the desired steering angle and the actual steering angle of the automatic irrigation vehicle, the required steering angle adjustment amount is calculated by using the fuzzy control algorithm.

[0138] After the desired steering angle is obtained by using the pure tracking algorithm, combined with the actual steering angle of the automatic irrigation vehicle, the actual steering angle required to be executed by the automatic irrigation vehicle is obtained by using the variable universe fuzzy sliding mode control algorithm.

[0139] As shown in Figure 6 , assuming that the front wheel steering angle of the automatic irrigation vehicle is small when driving, the vehicle dynamics equation can be described as:

[0140] ,

[0141] In formula (10), represents the longitudinal vehicle speed when the automatic irrigation vehicle is driving, represents the lateral vehicle speed, m represents the mass of the vehicle, represents the yaw rate of the automatic irrigation vehicle, , respectively represent the distance from the front wheel and the rear wheel to the center of mass of the automatic irrigation vehicle, , side forces of the front and rear wheels, respectively, is the moment of inertia at the center of mass of the automatic irrigation vehicle. When the wheel body is in the linear region, the relationship between the side force and the wheel body can be approximately expressed as:

[0142] ,

[0143] The side slip angles of the front and rear wheels of the automatic irrigation vehicle can be expressed as:

[0144] ,

[0145] Under the premise that the front wheel of the automatic irrigation vehicle makes a small angle steering, the side slip angle of the center of mass can be approximately expressed as: By combining equations (5)-(7), the two-degree-of-freedom model equation of the automatic irrigation vehicle about the yaw rate and the side slip angle of the center of mass can be obtained:

[0146] ,

[0147] where and are the side slip stiffness of the front and rear wheels, respectively.

[0148] For an uncertain system, when the system is subjected to internal parameter perturbation and external disturbance at the same time, the system state equation can be expressed as:

[0149] ,

[0150] where , is the internal parameter perturbation of the system, is the external disturbance of the system, is the state quantity, is the control quantity, includes the uncertainty of the system and the external disturbance.

[0151] According to equation (8), we can obtain:

[0152] ,

[0153] In the formula: , , , , , .

[0154] Therefore, the state equation of the controlled system studied in this embodiment can be expressed as:

[0155] ,

[0156] where The side-slip angle and the yaw rate can be expressed as:

[0157] ,

[0158] The gain value of the sliding mode control reaching law is selected as:

[0159] ,

[0160] where .

[0161] Since the side-slip angle cannot be directly controlled, and the ideal value of the side-slip angle of the automatic irrigation vehicle will have a large error compared with the actual value when the automatic irrigation vehicle is unstable, and the yaw rate is more capable of reflecting the overall motion trend of the automatic irrigation vehicle compared with the wheel angle, the tracking error of the system is selected as the difference between the actual yaw rate and the ideal yaw rate :

[0162] ,

[0163] In equation (19): is the yaw rate, which is calculated according to the expected angle value and the two-degree-of-freedom model; is the actual yaw rate. The switching function of the controller is selected as:

[0164] ,

[0165] The derivative of the switching function is:

[0166] ,

[0167] The sliding mode control law is designed as:

[0168] ,

[0169] The stability of the preliminary designed lateral sliding mode controller is proved by using Lyapunov theorem. The Lyapunov function is taken as:

[0170] ,

[0171] The derivative of equation (23) is:

[0172] ,

[0173] The sliding mode control law of equation (22) is substituted into equation (24) to obtain:

[0174] ,

[0175] where , so the designed controller meets the stability requirement.

[0176] Substitute equation (21) into equation (20), we can get an expression composed of parameters of vehicle dynamics model:

[0177] ,

[0178] Let According to the assumption, the yaw angular acceleration of the automatic irrigation vehicle at this time is Therefore, the control input front wheel steering angle can be expressed as:

[0179] ,

[0180] Substitute equation (22) into equation (21), we get:

[0181] ,

[0182] The control function prototype is:

[0183] ,

[0184] where represents the rate at which the system motion point approaches the switching surface, and when is larger, the approaching speed of the motion point will be faster, and the response speed of the control will also be faster, but it will also cause greater chattering. Therefore, the chattering of the sliding mode control is mainly caused by the approaching term , in order to ensure the control effect of the sliding mode controller, fuzzy control is introduced based on this.

[0185] According to equation (29), it can be seen that the existence of the sign function can effectively eliminate the unknown disturbance term, but it inevitably leads to chattering. Therefore, this embodiment uses adaptive fuzzy control based on switching fuzzification to improve the trajectory of the system near the sliding surface. Not only can the system adapt to various working conditions and have good elimination of different disturbance intensities, but also the discrete sign function can be continuous through fuzzy approximation, which can effectively reduce the chattering phenomenon. Therefore, this embodiment designs a variable switching gain and adjusts the switching gain according to the relative position and motion trend of the system and the sliding surface through fuzzy rules.

[0186] Let and be the fuzzy input quantities, be the output quantity, and the corresponding fuzzy language variables are . If ​If the current state of the sliding mode function is the same as the trend, the system is moving away from the sliding surface, and the switching gain should be increased If the current state of the sliding mode function is the same as the trend, the system is moving away from the sliding surface, and the switching gain should be increased If the current state of the sliding mode function is the same as the trend, the system is moving away from the sliding surface, and the switching gain should be increased At the same time The size of the fuzzy rule also needs to be considered, so as to further reasonably design the fuzzy rule. When is larger, the change amount should also be larger, and vice versa.

[0187] According to the principle of fuzzy control, if we want the fuzzy system to infinitely accurately approximate a changing function, theoretically we need infinite fuzzy rules to achieve this, which is almost impossible to complete. Therefore, we can further accurately approximate by adjusting the domain of discourse under the premise of constant number of rules and membership functions.

[0188] In this embodiment, the exponential scaling factor in the function model is selected to adaptively adjust the fuzzy domain of the three variables:

[0189] ,

[0190] Wherein is the scaling factor, which determines the scaling degree. The variable domain FSMC increases the feedback link, which can adjust the corresponding fuzzy domain according to the actual input and output range, and realize more accurate and rapid control.

[0191] Next, this embodiment adopts the axle load proportional distribution algorithm to distribute the four-wheel drive force according to the vertical load borne by each axle. When distributing by this method, not only the additional yaw moment should be met, but also the longitudinal force demand of the vehicle should be met.

[0192] The determination method of the estimated values of the front axle load and the rear axle load is as follows:

[0193] ,

[0194] In the formula: , are the front and rear axle vertical loads, is the height of the vehicle mass center, is the longitudinal acceleration of the mass center.

[0195] When the automatic irrigation vehicle distributes the longitudinal force of each wheel by the axle load proportional distribution algorithm, the longitudinal force of each wheel must meet the following formula in addition to meeting the total longitudinal force and yaw moment demand of the upper layer coordination controller:

[0196] ,

[0197] From this embodiment, the values of the longitudinal forces of the four wheels are:

[0198] ,

[0199] where B is the wheel base. Considering the adhesion limit of the road, the optimized four-wheel longitudinal forces of the automatic irrigation vehicle are obtained:

[0200] .

[0201] Finally, according to the steering angle adjustment amount and the wheel body parameters, the torque of each wheel hub motor is calculated.

[0202] According to the wheel body radius, the wheel body longitudinal force is converted into the required output wheel hub motor torque , which is finally converted into the speed of each wheel body by the applied wheel hub motor torque.

[0203] The above is only a preferred embodiment of the present application. For those skilled in the art, according to the idea of the present application, the specific implementation and application range will be changed, and the content of the specification should not be understood as a limitation of the present application.

Claims

1. An automatic irrigation system, characterized in that, include: Humidity detection device (1) includes several detection rods, and different numbers of the detection rods are arranged according to the differences in crops in different cultivated lands. Each detection rod has set coordinates and a unique number. The automatic irrigation vehicle (2) includes a control unit (28), an irrigation unit, a navigation unit (25), and a drive unit. The control unit (28) stores the coordinates and number of the detection rod, as well as the minimum humidity threshold for different types of farmland, and receives the real-time humidity value and number of the detection rod via wireless signal. The irrigation unit is used to irrigate farmland with humidity below the corresponding minimum humidity threshold. The navigation unit (25) is used to provide navigation for the automatic irrigation vehicle (2) and feed back the real-time positioning coordinates to the control unit (28). The drive unit is used to drive the wheels (27) of the automatic irrigation vehicle (2) to move. The irrigation unit, the navigation unit (25), and the drive unit are all electrically connected to the control unit (28). The control unit (28) controls the operation of the drive unit and the irrigation unit according to the real-time positioning coordinates and the real-time humidity value.

2. The automatic irrigation system of claim 1, wherein, The humidity detection device (1) further includes a first wireless transmission component (13). The detection rod includes a telescopic rod (11) and a humidity sensor (12). The humidity sensor (12) is located at one end of the telescopic rod (11) and inserted into the soil (100). The first wireless transmission component (13) is located at the other end of the telescopic rod (11) and is situated on the ground. The first wireless transmission component (13) is communicatively connected to the control unit (28).

3. The automatic irrigation system according to claim 1, characterized in that, The irrigation unit includes an irrigation pump (23), a water storage tank (22), and a sprinkler assembly. The sprinkler assembly is connected to the water storage tank (22) via the irrigation pump (23). The irrigation pump (23) is electrically connected to the control unit (28) and is controlled to open and close by the control unit (28). The water storage tank (22) is equipped with a water level sensor, which is connected to the control unit (28) in communication. When the control unit (28) receives a water shortage signal sent by the water level sensor, it controls the irrigation pump (23) to shut down, records the current coordinates, and controls the automatic irrigation vehicle (2) to return to the water replenishment point to replenish water.

4. The automatic irrigation system according to claim 1, characterized in that, The drive unit includes four hub motors (21), each hub motor (21) driving a wheel (27); the control unit (28) adjusts the rotational speed of the wheel (27) by controlling the torque of the hub motors (21).

5. The automatic irrigation system according to claim 1, characterized in that, The automatic irrigation vehicle (2) is equipped with an emergency stop button and an start button.

6. The automatic irrigation system according to claim 1, characterized in that, The automatic irrigation system also includes a power supply device, which includes a first power supply unit and a second power supply unit (26). The first power supply unit is used to supply power to the humidity detection device (1), and the second power supply unit (26) is used to supply power to the automatic irrigation vehicle (2).

7. The automatic irrigation system according to claim 1, characterized in that, The automatic irrigation system also includes water replenishment points and charging points, which are evenly distributed according to the cultivated land area.

8. The automatic irrigation system according to any one of claims 1-7, characterized in that, The automatic irrigation system is communicatively connected to the terminal equipment.

9. An automatic irrigation method, characterized in that, Applied to the automatic irrigation system as described in any one of claims 1-8, the automatic irrigation method includes the following steps: The humidity detection device (1) is installed in the cultivated land, and the number, density and insertion depth of the detection rods are determined according to the differences in crops; The control unit (28) acquires the real-time humidity value and number of each of the detection rods in real time, and determines the plot of land with humidity lower than the corresponding minimum humidity threshold as the target plot according to the preset analysis model; The control unit (28) controls the drive unit to drive the automatic irrigation vehicle (2) to the target plot under the guidance of the navigation unit (25), and then controls the drive unit to drive the automatic irrigation vehicle (2) to circle the target plot once, while controlling the irrigation unit to perform irrigation.

10. The automatic irrigation method according to claim 9, characterized in that, The steps for determining the target land parcel based on a pre-set analysis model include: The control unit (28) stores the real-time humidity values ​​and their numbers detected by each of the detection rods in the first data table; The real-time humidity values ​​in the first data table are polled, and the plots where the detection rod is located with real-time humidity values ​​less than the minimum humidity threshold of the plot are identified as target plots.

11. The automatic irrigation method according to claim 10, characterized in that, The irrigation unit includes an irrigation pump (23) and a water storage tank (22). The water storage tank (22) is equipped with a water level sensor. The automatic irrigation vehicle (2) is equipped with a second power supply (26). The method by which the irrigation unit irrigates the target plot further includes: When the automatic irrigation vehicle (2) travels to the target plot, the control unit (28) controls the power and working time of the irrigation pump (23) according to the required irrigation amount of the target plot, and controls the drive unit to drive the automatic irrigation vehicle (2) to circle the target plot once while controlling the irrigation unit to irrigate; During irrigation, the control unit (28) monitors the water level in the water storage tank (22) and the power of the second power supply (26) in real time; If the remaining water in the water tank (22) is insufficient or the power of the second power supply (26) is insufficient, the control unit (28) records the current coordinates and controls the automatic irrigation vehicle (2) to travel to the nearest water replenishment point or charging point to replenish water or charge. After water replenishment or charging is completed, the control unit (28) controls the automatic irrigation vehicle (2) to return to the recorded coordinates to continue irrigation; Once all target plots have been irrigated, the control unit (28) controls the automatic irrigation vehicle (2) to return to the base station.

12. The automatic irrigation method according to claim 11, characterized in that, The method for calculating the required irrigation amount for the target plot includes: The real-time humidity values ​​and their numbers of the detection rods whose real-time humidity values ​​are less than the minimum humidity threshold of the plot they are located in are stored in the second data table; Calculate the difference between the real-time humidity value and the corresponding minimum humidity threshold; The required irrigation amount for the target plot is calculated based on the difference and recorded in the second data table.

13. The automatic irrigation method according to claim 12, characterized in that, The control unit (28) controls the power and working time of the irrigation pump (23) according to the required irrigation amount recorded in the second data table; After each target plot is irrigated, the control unit (28) deletes the data of that target plot from the second data table until all data is deleted.

14. The automatic irrigation method according to claim 9, characterized in that, The drive unit includes four hub motors (21), each hub motor (21) driving one wheel (27). The control unit (28) controls the drive unit to drive the automatic irrigation vehicle (2) to the target plot in the following steps: The control unit (28) plans the target path (3) based on the positioning coordinates of the navigation unit (25) and the coordinates of the target plot, and sets the target rotation speed of each wheel (27) of the automatic irrigation vehicle (2); The control unit (28) controls the drive unit to drive each of the wheels (27) to travel at the target speed, and corrects the torque of each of the hub motors (21) based on the real-time positioning coordinates of the navigation unit (25) and the actual speed feedback of the wheels (27).

15. The automatic irrigation method according to claim 14, characterized in that, The method for correcting the torque of each of the hub motors (21) includes: By distributing different torques to the four wheels (27), the automatic irrigation vehicle (2) generates a yaw moment to adjust the travel angle; Using a fuzzy control method, the torque distribution of the four wheels (27) is adjusted by taking the deviation between the real-time driving direction of the automatic irrigation vehicle (2) and the target orientation as input.

16. The automatic irrigation method according to claim 15, characterized in that, The steps for adjusting torque using fuzzy control include: The positioning coordinates of the navigation unit (25) are processed to determine the nearest point (31) of the current position of the automatic irrigation vehicle (2); Set a pre-aiming distance, and find the path point closest to the pre-aiming distance along the target path (3) as the pre-aiming point (33); Calculate the desired rotation angle at the pre-aiming point (33); Based on the desired turning angle and the actual turning angle of the automatic irrigation vehicle (2), the required turning angle adjustment is calculated using a fuzzy control algorithm; The torque of each of the hub motors (21) is calculated based on the angle adjustment amount and the parameters of the wheel body (27).

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