Alfalfa planting and topdressing device and topdressing method

Abstract

The present application relates to the technical field of agricultural equipment, and discloses an alfalfa planting and topdressing device and a topdressing method, which comprise: a lightweight mobile frame, a connecting head connected with a power end, a front wheel and an infrared laser radar arranged at the front end, and an adjustable rear wheel group arranged at the rear end; a multi-modal detection unit integrated with the front wheel, a detection surface of the multi-modal detection unit and a scanning direction of the infrared laser radar form a spatial orthogonal layout, and the multi-modal detection unit comprises: a rolling trigger type gamma ray sensor which periodically emits rays while rotating with the front wheel; through the cooperative work of the multi-modal detection unit, the present device realizes comprehensive perception of soil deep nutrients, ion concentration, surface moisture and plant canopy, combines the terrain scanning function of the infrared laser radar, and dynamically generates a fertilizer formula and adjusts fertilization parameters, so that the precision and adaptability of fertilization are significantly improved, and the limitations of traditional single detection means are avoided.

Description

Technical Field

[0001] This invention relates to the field of agricultural equipment technology, specifically to an alfalfa planting topdressing device and topdressing method. Background Technology

[0002] Alfalfa (Medicago sativa), the most widely cultivated legume forage crop globally, is extensively used in animal husbandry and ecological restoration due to its high protein content and excellent feed value. Its growth cycle requires multiple harvests, placing extremely high demands on the dynamic balance of soil nutrients. Studies show that the absorption ratios of nitrogen, phosphorus, potassium, and micronutrients by alfalfa vary significantly at different growth stages and are greatly influenced by soil texture, moisture conditions, and climate. Furthermore, while alfalfa's root nitrogen-fixing capacity can partially meet its nitrogen requirements, the rational application of phosphorus and potassium fertilizers remains crucial for ensuring high and stable yields. However, traditional fertilization methods often rely on experience or fixed formulas, making it difficult to match the diverse spatial and temporal needs of alfalfa growth.

[0003] Current mainstream topdressing devices primarily employ mechanical or semi-automatic control modes, with their core technologies concentrated in fertilizer delivery mechanisms and basic environmental sensing modules. For example, some devices acquire single parameters through soil conductivity sensors or humidity probes and combine them with preset fertilization curves for variable control. While these devices can achieve rough on-demand fertilization, they have significant limitations: First, a single sensor cannot comprehensively reflect the soil nutrient status and the actual needs of the plants, easily leading to over- or under-fertilization due to data deviations; second, traditional devices mostly use fixed spraying structures, unable to dynamically adjust spraying parameters according to terrain undulations or alfalfa canopy density, resulting in uneven fertilizer distribution; third, existing equipment generally lacks the ability to monitor deep soil nutrients in real time, making it difficult to balance nutrient supply to the alfalfa root zone with the coordination of the surface soil environment. Furthermore, most devices rely on manual setting of operating parameters, lacking the ability to fuse and analyze multi-source heterogeneous data, causing fertilization decisions to lag behind actual needs.

[0004] It is worth noting that existing research has attempted to introduce remote sensing technology and IoT sensors into the field of precision fertilization. However, due to limitations in equipment integration, data processing capabilities, and field adaptability, the actual application results still have significant room for improvement. For example, while drone-based spectral monitoring can acquire large-scale canopy information, it is difficult to form a closed-loop control with ground-based fertilization equipment; while vehicle-mounted sensor arrays face problems such as complex structure and high maintenance costs. Therefore, how to construct an intelligent system that can simultaneously perceive multi-dimensional information from soil and plants and achieve dynamic optimization of fertilization parameters remains a critical technological bottleneck that urgently needs to be overcome in alfalfa cultivation. Summary of the Invention

[0005] The purpose of this invention is to provide an alfalfa planting topdressing device to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an alfalfa planting topdressing device, comprising:

[0007] The lightweight mobile frame has a connector for connecting to the power unit, a front wheel, and an infrared lidar at the front end, and an adjustable rear wheel set at the rear end.

[0008] A multimodal detection unit, integrated into the front wheel, has its detection surface arranged spatially orthogonally to the scanning direction of the infrared lidar, including:

[0009] A rolling-triggered gamma-ray sensor periodically emits rays as the front wheel rotates;

[0010] The contact-type electrochemical chip directly contacts the soil to obtain ion concentration;

[0011] A non-contact multispectral probe simultaneously acquires the reflectance spectrum of alfalfa canopy;

[0012] A non-contact microwave moisture meter that scans surface moisture while suspended in mid-air;

[0013] The fertilizer storage tank is fixed on a lightweight mobile frame and has multiple independent storage chambers inside. Each storage chamber is connected to a topdressing nozzle through a conveying pipe. The topdressing nozzle is installed on both sides of the lightweight mobile frame via an angle adjustment bracket.

[0014] Among them, the frame length L and the front wheel circumference C satisfy: K can be 3, 4, 5 or 6. Each time the front wheel rotates K times, a detection and fertilization cycle is completed. The fertilizer output ratio of each storage chamber and the angle of the topdressing nozzle are dynamically adjusted based on the fusion data of the multimodal detection unit.

[0015] According to the above technical solution, the front wheel includes symmetrically arranged wheel bodies, which are installed on the front end of the lightweight mobile frame by fixing bracket bolts. The wheel bodies are fixedly connected by a connecting shaft, and the multimodal detection unit is fixed on the connecting shaft.

[0016] According to the above technical solution, the multimodal detection unit includes:

[0017] The main detection shaft is rigidly fixed to the connecting shaft, and a first mounting platform is provided on the main detection shaft;

[0018] The secondary inspection shaft is mounted on the lightweight mobile frame via a buffer connection mechanism, and a second mounting platform is provided on the secondary inspection shaft.

[0019] Synchronous transmission assembly mechanically connects the main detection shaft and the auxiliary detection shaft;

[0020] The gamma-ray sensor and electrochemical chip are embedded in the first mounting platform, while the multispectral probe and microwave moisture meter are embedded in the second mounting platform.

[0021] According to the above technical solution, the buffer connection mechanism includes:

[0022] The axle seat is welded and fixed to the bottom of the lightweight mobile vehicle frame.

[0023] The lifting block is slidably disposed in the vertical groove of the bearing seat;

[0024] The elastic element abuts against the top of the bearing seat at its upper end and against the upper surface of the lifting block at its lower end;

[0025] The grounding wheel is fixed to the bottom of the lifting block by bolts, and the diameter of the grounding wheel is smaller than that of the front wheel.

[0026] According to the above technical solution, the synchronous transmission assembly includes:

[0027] The drive wheel is keyed to the main detection shaft;

[0028] Driven wheel, keyed to the auxiliary detection shaft;

[0029] Synchronous belts connect the driving pulley and the driven pulley through a meshing action.

[0030] Tension regulator, consisting of:

[0031] The movable tensioning pulley presses against the outer surface of the timing belt;

[0032] The electric telescopic cylinder is fixed to the side wall of the lightweight mobile frame via a bent rod fixing seat, and drives the movable tension wheel to move along the direction perpendicular to the plane of the synchronous belt.

[0033] Tension sensor detects the tension of the synchronous belt in real time and feeds it back to the control system;

[0034] The tension wheel axis is parallel to the axes of the driving wheel and the driven wheel, and the three are arranged in an isosceles triangle.

[0035] According to the above technical solution, the fertilizer storage tank includes:

[0036] An integrated tank body has several evenly distributed partitions inside, which divide the integrated tank body into multiple storage chambers. Each partition consists of two mirror-symmetrically arranged baffles, with an air-isolated cavity formed between the baffles. The storage chambers include:

[0037] The nitrogen fertilizer storage chamber is equipped with a nitrogen fertilizer inlet and a nitrogen exhaust outlet at the top, and has an integrated nitrogen concentration sensor inside. The inner wall is lined with PTFE.

[0038] The phosphate and potassium fertilizer storage chamber has a phosphate and potassium fertilizer inlet at the top, an integrated magnetic stirr inside, and a heat-insulating jacket on the side wall.

[0039] The micro-fertilizer storage chamber is equipped with a micro-fertilizer inlet and a nitrogen filling inlet at the top, and is covered with a black HDPE light-shielding film on the outside.

[0040] The organic fertilizer storage chamber has an organic fertilizer inlet at the top and integrates a temperature control plate and dissolved oxygen probe inside.

[0041] According to the above technical solution, the angle adjustment frame includes:

[0042] A mounting base is installed on the side wall of the lightweight mobile frame;

[0043] The lateral movement component drives the first clamp to move laterally;

[0044] The longitudinal movement component drives the second clamp to move longitudinally.

[0045] The two ends of the topdressing nozzle are respectively clamped to the first clamp and the second clamp.

[0046] According to the above technical solution, the lateral movement component includes:

[0047] The first servo motor is bolted to the transverse slide groove of the mounting base;

[0048] The threaded rod is coaxially connected to the output end of the first servo motor.

[0049] The first support rod has a fixed threaded slider at its lower end that engages with the threaded rod, and its upper end is movably connected to the bottom of the first clamp via a ball joint.

[0050] The longitudinal movement component includes:

[0051] The second servo motor is bolted to the mounting base;

[0052] The crankshaft key connects to the output of the second servo motor.

[0053] Connecting rod, one end of which is hinged to the eccentric position of the crankshaft;

[0054] The second support rod has its lower end slidably connected to the guide rod via a guide slider, and its upper end is movably connected to the bottom of the second clamp via a ball joint.

[0055] The linkage rod is fixed to the side wall of the second support rod, and its end is hinged to the connecting rod.

[0056] According to the above technical solution, the adjustable rear wheel assembly includes:

[0057] The wheel frame is bolted to the lower end of the lightweight mobile vehicle frame via side wing plates.

[0058] The rear wheel is located inside the wheel frame, and its diameter is smaller than that of the front wheel but larger than that of the ground wheel.

[0059] A limit stop is located between the side wing and the lightweight mobile frame.

[0060] A topdressing method for alfalfa planting topdressing device includes the following steps:

[0061] S1, Terrain Scan: Infrared lidar scans the terrain of the work area and generates elevation compensation parameters;

[0062] S2, Multimodal Detection:

[0063] The rotation of the front wheel triggers a gamma-ray sensor to scan deep soil nutrients;

[0064] Electrochemical chips are used to obtain ion concentrations by contacting soil.

[0065] Microwave moisture meter is used to scan the distribution of surface moisture in mid-air.

[0066] Multispectral probes were used to collect the reflectance spectra of alfalfa canopies;

[0067] S3, Data Fusion: Integrates topographic data, soil nutrients, ion concentration, moisture distribution, and canopy spectrum to generate fertilizer formulas;

[0068] S4, Dynamic Adjustment:

[0069] Adjust the opening degree of the control valves in each storage chamber according to the fertilizer formula;

[0070] Adjusting the lateral spray angle of the topdressing nozzle based on canopy spectral density;

[0071] Adjust the circulating spraying speed of the topdressing nozzles based on terrain elevation compensation parameters;

[0072] S5, Periodic Verification: After every K laps, verify the uniformity of fertilizer coverage and calibrate the test data.

[0073] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0074] (1) Synergy between multimodal detection and precision fertilization: Through the coordinated operation of multimodal detection units (γ-ray sensor, electrochemical chip, multispectral probe, microwave moisture meter), this device achieves comprehensive perception of deep soil nutrients, ion concentration, surface moisture and plant canopy. Combined with the terrain scanning function of infrared lidar, the system can dynamically generate fertilizer formula and adjust fertilization parameters, which significantly improves the accuracy and adaptability of fertilization and avoids the limitations of traditional single detection methods.

[0075] (2) High efficiency of mechanical synchronization and cycle control: The circumference C of the front wheel and the length L of the lightweight mobile frame satisfy the following conditions. (K is 3, 4, 5, or 6), the fertilization cycle is detected naturally through mechanical movement. No additional encoders or complex electronic control systems are required; periodic detection and fertilization operations are completed simply by the rotation of the wheels, reducing system complexity and improving operational efficiency.

[0076] (3) High detection accuracy: The buffer connection mechanism (shaft seat, lifting block, elastic element, ground wheel) absorbs the impact of ground undulation through the elastic element, ensuring that the multispectral probe and microwave moisture meter on the secondary detection shaft always maintain a fixed distance from the ground. This design avoids the deviation of detection data caused by uneven ground and ensures the stability of non-contact sensors in complex terrain.

[0077] (4) High environmental adaptability: The fertilizer storage tank is designed with multiple independent chambers (nitrogen fertilizer storage chamber, phosphorus and potassium fertilizer storage chamber, micro-fertilizer storage chamber, and organic fertilizer storage chamber). Combined with targeted measures such as PTFE lining, magnetic stirring, light-shielding film, and temperature control plate, it effectively prolongs the activity and storage stability of different fertilizers. The air isolation chamber of the isolation component further prevents cross-contamination and provides a reliable basis for accurate proportioning.

[0078] (5) Strong variable spraying capability: The angle adjustment frame realizes the independent adjustment of the topdressing nozzle in the horizontal and vertical directions through the coordinated control of the horizontal and vertical moving components. The horizontal movement of the first clamp changes the center position of the spraying range, the vertical movement of the second clamp adjusts the spraying range angle, and the support rod adjusts the pitch angle, so that the nozzle can dynamically optimize the spraying parameters according to the alfalfa canopy density and terrain elevation, which significantly improves the fertilizer coverage and utilization rate. Attached Figure Description

[0079] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0080] Figure 1 This is a first perspective view of the present invention;

[0081] Figure 2 This is a second perspective view of the present invention;

[0082] Figure 3 This is a third perspective view of the present invention;

[0083] Figure 4 This is a fourth perspective schematic diagram of the present invention;

[0084] Figure 5 This is the fifth perspective schematic diagram of the present invention;

[0085] Figure 6 This is a first partial three-dimensional schematic diagram of the present invention;

[0086] Figure 7 This is a second partial perspective view of the present invention;

[0087] Figure 8 This is a third partial perspective view of the present invention;

[0088] Figure 9 This is a fourth partial perspective view of the present invention;

[0089] Figure 10 This is a fifth partial perspective view of the present invention;

[0090] Figure 11 This is a sixth partial perspective view of the present invention;

[0091] Figure 12 This is a third-dimensional schematic diagram of the seventh part of the present invention;

[0092] Figure 13 This is the present invention. Figure 7 A magnified view of a portion of point A in the middle;

[0093] In the diagram: 1-Lightweight mobile frame, 11-Connector, 12-Front wheel, 121-Wheel body, 122-Fixed frame, 123-Connecting axle, 13-Adjustable rear wheel assembly, 131-Wheel frame, 132-Side wing plate, 133-Rear wheel, 134-Limit stop, 14-Infrared lidar, 2-Multi-modal detection unit, 21-Main detection shaft, 211-First mounting platform, 22-Secondary detection shaft, 221-Second mounting platform, 23-Buffer connection mechanism, 231-Axle seat, 232-Lifting mechanism Block, 233-Elastic element, 234-Grounding wheel, 24-Synchronous transmission assembly, 241-Driving wheel, 242-Driven wheel, 243-Synchronous belt, 244-Tension adjuster, 244a-Movable tension wheel, 244b-Electric telescopic cylinder, 244c-Tension sensor, 244d-Bend rod fixing seat, 25-Gamma ray sensor, 26-Electrochemical chip, 27-Multispectral probe, 28-Microwave moisture meter, 3-Fertilizer storage tank, 30-Integrated tank, 31-Storage chamber, 311-Nitrogen Fertilizer storage chamber, 311a-Nitrogen fertilizer inlet, 311b-Nitrogen exhaust port, 311c-Nitrogen concentration sensor, 311d-PTFE liner, 312-Phosphorus and potassium fertilizer storage chamber, 312a-Phosphorus and potassium fertilizer inlet, 312b-Magnetic stirrer, 312c-Insulation jacket, 313-Micro-fertilizer storage chamber, 313a-Micro-fertilizer inlet, 313b-Nitrogen filling port, 313c-Black HDPE light-blocking film, 314-Organic fertilizer storage chamber, 314a-Organic fertilizer inlet, 314b-Temperature control panel 314c-Dissolved oxygen probe, 32-Delivery pipe, 33-Topdressing nozzle, 4-Angle adjustment frame, 41-Fixed base, 42-Horizontal movement assembly, 421-First servo motor, 422-Threaded rod, 423-First support rod, 424-Threaded slider, 43-First clamp, 44-Longitudinal movement assembly, 441-Second servo motor, 442-Crank disc, 443-Connecting rod, 444-Second support rod, 445-Guide slider, 446-Guide rod, 447-Linkage rod, 45-Second clamp. Detailed Implementation

[0094] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0095] Please see Figure 1-13 The present invention provides a technical solution: an alfalfa planting topdressing device, comprising:

[0096] The lightweight mobile frame 1 has a connector 11 for connecting to the power end, a front wheel 12 and an infrared laser radar 14 at the front end, and an adjustable rear wheel set 13 at the rear end.

[0097] A multimodal detection unit 2, integrated into the front wheel 12, has its detection surface arranged orthogonally to the scanning direction of the infrared lidar 14, and includes:

[0098] The rolling-triggered gamma-ray sensor 25 periodically emits rays as the front wheel 12 rotates;

[0099] The contact-type electrochemical chip 26 directly contacts the soil to obtain ion concentration;

[0100] The non-contact multispectral probe 27 simultaneously acquires the reflectance spectrum of alfalfa canopy;

[0101] The non-contact microwave moisture meter 28 scans surface moisture in mid-air.

[0102] Fertilizer storage tank 3 is fixed on lightweight mobile frame 1 and has multiple independent storage chambers 31 inside. Each storage chamber 31 is connected to a topdressing nozzle 33 through a conveying pipe 32. The topdressing nozzle 33 is installed on both sides of the lightweight mobile frame 1 via an angle adjustment frame 4.

[0103] Among them, the frame length L and the circumference C of the front wheel 12 satisfy: K is 3, 4, 5 or 6. Each time the front wheel 12 rotates K times, a detection and fertilization cycle is completed. Based on the fusion data of the multimodal detection unit 2, the fertilizer output ratio of each storage chamber 31 and the angle of the topdressing nozzle 33 are dynamically adjusted.

[0104] Specifically, the front wheel 12 includes symmetrically arranged wheel bodies 121. The wheel bodies 121 are bolted to the front end of the lightweight mobile frame 1 by a fixing bracket 122. The wheel bodies 121 are fixedly connected by a connecting shaft 123. The multimodal detection unit 2 is fixed on the connecting shaft 123.

[0105] The front wheel 12, as a key moving component of the alfalfa planting and topdressing device, is composed of symmetrically arranged wheel bodies 121, a fixed frame 122, and a connecting shaft 123. The two wheel bodies 121 are arranged symmetrically to form a stable front support structure, which, together with the adjustable rear wheel set 13, constitutes a four-point support system, effectively ensuring the lateral stability and ground adaptability of the lightweight mobile frame 1 during movement. The wheel body 121 adopts a thin and large-diameter structural design, which has a dual function. On the one hand, it reduces the contact area between the wheel body and the ground, reducing the degree of soil compaction and helping to maintain the integrity of the soil structure. On the other hand, it reduces the contact area between the wheel body and the ground, reducing the degree of soil compaction and helping to maintain the integrity of the soil structure. This provides the necessary space for the multimodal detection unit 2 installed in the middle, ensuring that the detection unit can work effectively close to the ground. The wheel 121 is bolted to the front end of the lightweight mobile frame 1 via the fixing bracket 122. This detachable connection method facilitates maintenance and replacement. The two wheels 121 are rigidly connected by the connecting shaft 123, ensuring that the two wheels 121 rotate synchronously during travel, providing a foundation for the stable operation of the multimodal detection unit 2. The diameter of the front wheel 12 has a specific geometric relationship with the length of the lightweight mobile frame 1, that is, the frame length L and the circumference C of the front wheel 12 satisfy the following condition: Where K is 3, 4, 5, or 6, the frame length L is set to the overall length of the device, that is, including the width of the pop-out end of the front wheel 12, and the circumference C of the front wheel 12 is adopted. This design establishes a fixed proportional relationship between the rotation of the front wheel 12 and the travel distance of the device. Each time the front wheel 12 rotates K times (a full rotation), the device completes a full detection and fertilization cycle, which also constitutes a spraying unit. At this time, the system dynamically adjusts the fertilizer output ratio of each storage chamber 31 and the angle of the topdressing nozzle 33 based on the fused data collected by the multimodal detection unit 2. This achieves customized variable spraying for different spraying units, enabling customized topdressing with one unit, one detection, and one spraying. This design cleverly binds mechanical motion to the detection and fertilization cycle, eliminating the need for additional encoders or counting devices; it achieves this solely through the natural rotation of the front wheel 12. It can realize periodic detection and fertilization control. After the front wheel 12 rotates K times, the system will average the detection data collected within these K rotations and use it as the basis for dynamically adjusting the fertilizer output ratio, ensuring the accuracy and consistency of fertilization. The rotation of the front wheel 12 not only drives the movement of the device, but also serves as the basis for the movement of the multimodal detection unit 2, enabling the detection unit to move closer to the ground synchronously with the movement, realizing continuous and uniform collection of soil and plant information. At the same time, the precise correspondence between the rotation cycle of the front wheel 12 and the detection and fertilization cycle enables the entire device to achieve closed-loop control of "perception-decision-execution", providing reliable technical support for the precise topdressing of alfalfa.

[0106] The K-value is determined based on the actual terrain conditions, alfalfa growth density, and required detection accuracy. Different K-values ​​result in different detection effects and operational efficiency. When K=3, the detection cycle is short, with the device completing one detection and fertilization cycle every three rotations. This setting is suitable for areas with significant terrain undulations or high alfalfa planting density, as the shorter cycle allows for faster acquisition of terrain change information, timely adjustment of fertilization parameters, and avoidance of uneven fertilization due to terrain changes. However, a smaller K-value can lead to a higher detection frequency, potentially increasing the system load, especially on flat terrain, which may result in repeated data collection. When K=4, this is a more balanced choice, ensuring both the averaging effect of the detection data and avoiding an excessively long detection cycle. It is suitable for most conventional alfalfa planting scenarios, effectively balancing detection accuracy and operational efficiency, ensuring both data quality and device operating efficiency. When K=5, the detection cycle is longer, resulting in better data averaging. This setting is suitable for areas with relatively flat terrain and low alfalfa planting density, as it better filters out local terrain fluctuations. The K value helps to mitigate the impact of dynamic changes on the detection data, resulting in more stable soil nutrient information. However, a larger K value also means a slower data update speed, which may lead to delayed responses in areas with rapidly changing terrain. When K=6, the detection cycle is the longest, and the average data effect is the best. This setting is suitable for very flat terrain and uniform alfalfa planting areas. This setting can smooth out local anomalies to the greatest extent and obtain more reliable soil nutrient information. However, an excessively large K value may lead to insufficient adjustment of fertilization parameters in complex terrain or scenarios requiring rapid response, affecting the accuracy of fertilization. The larger the K value, the more likely it is to cause problems. The more average and stable the detection data, the slower the response speed. The smaller the K value, the faster the response speed, but the greater the data fluctuation may be. For sandy soil, a K value of 3 or 4 is recommended. Sandy soil loses nutrients quickly and requires high-frequency monitoring and water and fertilizer replenishment to prevent the leaching of fast-acting fertilizer. For clay soil, a K value of 5 or 6 is recommended. Clay soil has strong slow-release properties of nutrients, and low-frequency monitoring avoids energy waste and extends the equipment's endurance. In practical applications, the most suitable K value should be selected according to the terrain characteristics, planting density, and fertilization accuracy requirements of the alfalfa field to achieve the best balance between the reliability of detection data and the efficiency of fertilization operations.

[0107] Specifically, the multimodal detection unit 2 includes:

[0108] The main detection shaft 21 is rigidly fixed to the connecting shaft 123, and the main detection shaft 21 is provided with a first mounting platform 211;

[0109] The secondary detection shaft 22 is mounted on the lightweight mobile frame 1 via a buffer connection mechanism 23, and a second mounting platform 221 is provided on the secondary detection shaft 22.

[0110] Synchronous transmission assembly 24 mechanically connects main detection shaft 21 and auxiliary detection shaft 22;

[0111] The gamma-ray sensor 25 and the electrochemical chip 26 are embedded in the first mounting platform 211, and the multispectral probe 27 and the microwave moisture meter 28 are embedded in the second mounting platform 221.

[0112] The main detection shaft 21 is rigidly fixed to the connecting shaft 123 and rotates synchronously with the front wheel 12. The first mounting platform 211 on it remains vertically downward during detection, ensuring that the probes of the gamma-ray sensor 25 and the electrochemical chip 26 operate vertically downward. The gamma-ray sensor 25 periodically emits rays during rotation to detect deep soil nutrients, while the electrochemical chip 26 probe directly contacts the soil surface to acquire real-time soil ion concentration data. The secondary detection shaft 22 is mounted on the lightweight mobile frame 1 via a buffer connection mechanism 23. The second mounting platform 221 on it remains horizontally backward during detection. The multispectral probe 27 and the microwave moisture meter 28 are embedded in the second mounting platform 221, used to collect alfalfa canopy reflectance spectra and scan surface moisture distribution, respectively. It should be noted that the rotation range of the first mounting platform 211 and the fixed position of the second mounting platform 221 are spatially isolated. Since the secondary detection shaft 22 is located outside the rotation range of the first mounting platform 211, and the first mounting platform 211... With the vertically downward-facing and the horizontally rearward-facing second mounting platform 221, the two form an orthogonal layout in space. Therefore, no physical contact or motion interference will occur during the detection process. The synchronous transmission component 24 ensures that the main detection shaft 21 and the auxiliary detection shaft 22 rotate synchronously, enabling the two detection platforms to work simultaneously and acquire synchronous soil and plant information. The gamma-ray sensor 25 and the electrochemical chip 26 perform periodic detection as the front wheel 12 rotates, while the multispectral probe 27 and the microwave moisture meter 28 maintain a relatively stable state, jointly completing the synchronous acquisition of multi-dimensional data such as deep soil nutrients, soil ion concentration, plant canopy spectrum, and surface moisture. This spatial layout design not only ensures the synchronization of detection but also avoids data interference caused by mechanical movement, providing high-quality input data for subsequent data fusion and precise fertilization decisions. At the same time, this design also makes full use of the rotation characteristics of the front wheel 12, allowing the detection unit to naturally approach the ground as it moves, achieving continuous and uniform acquisition of soil and plant information.

[0113] Specifically, the buffer connection mechanism 23 includes:

[0114] Axle seat 231 is welded and fixed to the bottom of the lightweight mobile frame 1;

[0115] The lifting block 232 is slidably disposed in the vertical groove of the bearing seat 231;

[0116] The elastic element 233 abuts against the top of the bearing seat 231 at its upper end and against the upper surface of the lifting block 232 at its lower end.

[0117] Grounding wheel 234 is fixed to the bottom of lifting block 232 by bolts. The diameter of grounding wheel 234 is smaller than the diameter of front wheel 12.

[0118] The design of the buffer connection mechanism 23 effectively solves the problem of maintaining the detection accuracy of the multimodal detection unit 2 under undulating ground conditions, ensuring that the multispectral probe 27 and microwave moisture meter 28 on the second installation platform 221 always maintain a fixed distance from the ground. This mechanism consists of four key components: axle seat 231, lifting block 232, elastic element 233, and grounding wheel 234. The axle seat 231 is firmly fixed to the bottom of the lightweight mobile frame 1 by bolts, serving as the supporting foundation for the entire buffer structure. The lifting block 232 can slide freely up and down in the vertical groove of the axle seat 231, providing guidance for the buffer movement. The elastic element 233 is located between the top of the axle seat 231 and the upper surface of the lifting block 232, playing a key buffering role. The grounding wheel 234 is fixed to the bottom of the lifting block 232 by bolts, and its diameter is smaller than that of the front wheel 12, ensuring that the grounding wheel 234 can move flexibly. To adapt to ground undulations, when the lightweight mobile frame 1 travels on uneven ground, the ground wheel 234 first contacts the ground and moves up and down accordingly. Due to the small diameter of the ground wheel 234, it can quickly sense changes in ground undulations and drive the lifting block 232 to move within the vertical groove of the axle seat 231. During this process, the elastic element 233 deforms, absorbing the impact energy brought by the ground undulations and preventing vibration from being transmitted to the secondary detection shaft 22. This design allows the secondary detection shaft 22 to remain relatively stable, while ensuring that the multispectral probe 27 and microwave moisture meter 28 on the second mounting platform 221 always maintain a fixed distance from the ground. Compared with traditional fixed installation, this buffer design avoids changes in the distance between the sensor and the ground caused by uneven ground, thereby ensuring the accuracy and consistency of the canopy spectral data acquired by the multispectral probe 27 and the surface moisture data scanned by the microwave moisture meter 28.

[0119] Specifically, the synchronous transmission assembly 24 includes:

[0120] The drive wheel 241 is keyed to the main detection shaft 21;

[0121] Driven wheel 242 is keyed to auxiliary detection shaft 22;

[0122] Synchronous belt 243 meshes with driving pulley 241 and driven pulley 242;

[0123] Tension regulator 244, consisting of:

[0124] The movable tensioning wheel 244a presses the outer surface of the timing belt 243;

[0125] The electric telescopic cylinder 244b is fixed to the side wall of the lightweight mobile frame 1 via the bent rod fixing seat 244d, and drives the movable tension wheel 244a to move along the direction of the vertical synchronous belt 243 plane;

[0126] Tension sensor 244c detects the tension of synchronous belt 243 in real time and feeds it back to the control system;

[0127] Among them, the axis of tensioning wheel 244a is parallel to the axes of driving wheel 241 and driven wheel 242, and the three are arranged in an isosceles triangle.

[0128] As the core transmission component of the multimodal detection unit 2, the synchronous transmission assembly 24 is designed to ensure precise synchronous rotation between the main detection shaft 21 and the auxiliary detection shaft 22, providing a reliable guarantee for the synchronization of detection data. The driving wheel 241 is firmly mounted on the main detection shaft 21 via a key connection, and rotates synchronously with the front wheel 12, enabling the main detection shaft 21 to rotate synchronously with the rolling of the front wheel 12. The driven wheel 242 is also fixed to the auxiliary detection shaft 22 via a key connection, ensuring that the rotation of the auxiliary detection shaft 22 is synchronized with the main detection shaft 21. The detection shaft 21 remains aligned, and the synchronous belt 243 serves as the mechanical connection medium. Its inner circumferential surface is provided with equally spaced teeth that mesh with the tooth grooves of the driving pulley 241 and the driven pulley 242, achieving precise power transmission. The meshing connection of the synchronous belt 243 ensures a constant transmission ratio between the main detection shaft 21 and the auxiliary detection shaft 22, avoiding deviations in detection data caused by slippage. The tension adjuster 244 consists of three parts: a movable tension wheel 244a, an electric telescopic cylinder 244b, and a tension sensor 244c. The movable tension wheel 244a… 4a presses the outer surface of the timing belt 243. Driven by the electric telescopic cylinder 244b, it can move in a direction perpendicular to the plane of the timing belt 243, achieving precise adjustment of the tension of the timing belt 243. The tension sensor 244c detects the tension of the timing belt 243 in real time and feeds the data back to the control system, forming a closed-loop adjustment mechanism. The axis of the tensioning pulley 244a is parallel to the axes of the driving pulley 241 and the driven pulley 242, and the three form an isosceles triangle. This design ensures that the timing belt 243 is evenly stressed and avoids uneven tension. To prevent wear or slippage of the synchronous belt due to uneven tension, limiting plates can be installed on both sides of the tensioning wheel 244a to increase the stability of the synchronous belt 243. This design of the synchronous transmission assembly 24 enables the main detection shaft 21 and the auxiliary detection shaft 22 to maintain precise synchronous rotation, ensuring that the detection data of the gamma-ray sensor 25, electrochemical chip 26, multispectral probe 27, and microwave moisture analyzer 28 are consistent in time. This is beneficial for the fusion data processing of the multimodal detection unit 2 and avoids data mismatch problems caused by detection time differences.

[0129] Specifically, the fertilizer storage tank 3 includes:

[0130] An integrated tank 30 has several partitions 34 evenly distributed inside, which divide the integrated tank 30 into multiple storage chambers 31. Each partition 34 is composed of two mirror-symmetrically arranged baffles, with an air-isolated cavity 341 formed between the baffles. Each storage chamber 31 includes:

[0131] The nitrogen fertilizer storage chamber 311 has a nitrogen fertilizer inlet 311a and a nitrogen exhaust port 311b at the top, an integrated nitrogen concentration sensor 311c inside, and a PTFE lining 311d on the inner wall.

[0132] The phosphorus and potassium fertilizer storage chamber 312 has a phosphorus and potassium fertilizer inlet 312a at the top, an integrated magnetic stirrer 312b inside, and a heat-insulating jacket 312c on the side wall.

[0133] The micro-fertilizer storage chamber 313 has a micro-fertilizer inlet 313a and a nitrogen filling inlet 313b on the top, and is covered with a black HDPE light-shielding film 313c on the outside.

[0134] The organic fertilizer storage chamber 314 has an organic fertilizer inlet 314a at the top and integrates a temperature control plate 314b and a dissolved oxygen probe 314c inside.

[0135] As the core fertilizer storage component of the alfalfa planting topdressing device, the integrated tank body 30 is the basic structure of the entire storage tank. It adopts an integral molding process, avoiding the leakage risk caused by welding seams. Internally, evenly distributed isolation components 34 divide the tank body into multiple independent storage chambers 31. Each isolation component 34 consists of two mirror-symmetrically arranged partitions, forming an air-isolated cavity 341 between the partitions. This design not only effectively prevents cross-contamination between different fertilizers but also reduces heat conduction, ensuring the environmental independence of each storage chamber 31. The nitrogen fertilizer storage chamber 311 is specifically designed for storing nitrogen fertilizer, and its top is equipped with a nitrogen fertilizer inlet 311a and a nitrogen exhaust port 311b. The 1b design allows for timely venting of gases that may be generated during nitrogen fertilizer storage, preventing pressure buildup inside the tank. The integrated nitrogen concentration sensor 311c monitors nitrogen concentration in real time, providing data support for precise proportioning. The PTFE lining 311d on the inner wall offers excellent corrosion resistance, effectively preventing nitrogen fertilizer from corroding the tank and extending its service life. The phosphate and potassium fertilizer storage chamber 312 stores phosphate and potassium fertilizer, with a phosphate and potassium fertilizer inlet 312a at the top. The integrated magnetic stirrer 312b thoroughly stirs the phosphate and potassium fertilizer without compromising the tank's seal, preventing sedimentation and clumping, and ensuring fertilizer uniformity. The side walls are equipped with an insulation jacket 31. 2c maintains a stable internal temperature, preventing crystallization or deterioration of phosphate and potassium fertilizers due to temperature changes. The micro-fertilizer storage chamber 313 is specifically designed for storing easily photodegradable micro-fertilizers. It features a micro-fertilizer inlet 313a and a nitrogen inlet 313b at the top. The nitrogen inlet 313b allows nitrogen to be added after filling with micro-fertilizers, creating an inert gas protective environment to prevent oxidation. The external black HDPE light-blocking film 313c effectively blocks light, preventing the decomposition of photosensitive micro-fertilizers by light exposure and ensuring their activity. The organic fertilizer storage chamber 314 stores organic fertilizers. It features an organic fertilizer inlet 314a at the top, and an integrated temperature control plate 314b precisely controls the internal temperature to maintain the organic fertilizer's... The dissolved oxygen probe 314c can monitor the dissolved oxygen content in the tank in real time to provide the necessary oxygen conditions for the fermentation process of organic fertilizer and ensure the quality of organic fertilizer. This multi-chamber fertilizer storage tank 3, with its independent design, ensures the stability and activity of various fertilizers during storage through targeted environmental control measures. The independent design of each storage chamber 31 enables the device to dynamically adjust the fertilizer output ratio of each chamber according to the fusion data of the multi-modal detection unit 2, so as to achieve precise variable fertilization. At the same time, the air isolation chamber 341 design of the isolation component 34 effectively avoids the mutual influence between different fertilizers, providing a basic guarantee for the precise mixing of multi-component fertilizers.

[0136] Specifically, the angle adjustment bracket 4 includes:

[0137] The mounting base 41 is installed on the side wall of the lightweight mobile frame 1;

[0138] The lateral movement component 42 drives the first clamp 43 to move laterally;

[0139] The longitudinal moving component 44 drives the second clamp 45 to move longitudinally;

[0140] The first and second ends of the topdressing nozzle 33 are respectively clamped to the first clamp 43 and the second clamp 45;

[0141] Specifically, the lateral movement component 42 includes:

[0142] The first servo motor 421 is bolted to the transverse slide groove of the mounting base 41;

[0143] The threaded rod 422 is coaxially connected to the output end of the first servo motor 421;

[0144] The first support rod 423 has a fixed threaded slider 424 at its lower end that engages with the threaded rod 422, and its upper end is movably connected to the bottom of the first clamp 43 via a ball joint.

[0145] The longitudinal movement component 44 includes:

[0146] The second servo motor 441 is bolted to the mounting base 41;

[0147] Crank 442 is keyed to the output of the second servo motor 441;

[0148] Connecting rod 443 is hinged at one end to the eccentric position of crank disc 442;

[0149] The second support rod 444 has its lower end slidably connected to the guide rod 446 via the guide slider 445, and its upper end is movably connected to the bottom of the second clamp 45 via a ball joint.

[0150] Linkage rod 447 fixes the side wall of the second support rod 444, and its end is hinged to the connecting rod 443;

[0151] The lateral movement component 42, as the core control component of the angle adjustment frame 4, is designed to achieve precise horizontal adjustment of the first clamp 43, thereby controlling the spraying range of the topdressing nozzle 33. The first servo motor 421 is fixed to the lateral slide groove of the fixed base 41 by bolts, serving as the driving force source for lateral movement. The output end of the first servo motor 421 is coaxially connected to the threaded rod 422. When the motor starts, the threaded rod 422 rotates accordingly. The threaded slider 424 is fixed to the lower end of the first support rod 423 and engages with the threaded rod 422. When the threaded rod 422 rotates... At this time, the threaded slider 424 moves axially in the helical groove of the threaded rod 422, driving the first support rod 423 to move horizontally. The upper end of the first support rod 423 is movably connected to the bottom of the first clamp 43 through a ball joint. This ball joint connection allows the first clamp 43 to achieve smooth horizontal displacement as the first support rod 423 moves. The longitudinal movement component 44 drives the crank disk 442 to rotate through the second servo motor 441, realizing the horizontal angle adjustment of the topdressing nozzle 33. The second servo motor 441 is bolted to the fixed base 41, and its output end is keyed to the crank disk. 442, the eccentric position of the crank disc 442 is connected to the connecting rod 443 via a hinge, converting the rotational motion into reciprocating linear motion. The lower end of the second support rod 444 is slidably connected to the guide rod 446 via the guide slider 445. This guiding structure ensures the stable and reliable horizontal movement of the second support rod 444. The upper end of the second support rod 444 is movably connected to the bottom of the second clamp 45 via a ball joint, allowing the second clamp 45 to change position as the second support rod 444 moves left and right. If there is a need for vertical adjustment of the spray, the first support rod 423 and the second support rod 444 in this device... The rod 444 can be replaced by an electric telescopic support rod. The coordinated work of the lateral movement component 42 and the longitudinal movement component 44 in this device enables the topdressing nozzle 33 to achieve precise angle adjustment in a three-dimensional plane. The lateral movement component 42 adjusts the horizontal position of the first clamp 43 to determine the center of the spraying range, while the longitudinal movement component 44 controls the spraying range of the nozzle by adjusting the position of the second clamp 45. This makes the adjustment of the spraying range more flexible and precise, and can dynamically adjust the spraying parameters according to the alfalfa canopy density and terrain elevation to achieve precise control of variable fertilization.

[0152] Specifically, the adjustable rear wheel assembly 13 includes:

[0153] The wheel frame 131 is bolted to the lower end of the lightweight mobile frame 1 via the side wing plate 132.

[0154] The rear wheel 133 is located inside the wheel frame 131, and its diameter is smaller than that of the front wheel 12 but larger than that of the ground wheel 234.

[0155] A limiting block 134 is disposed between the side wing plate 132 and the lightweight mobile frame 1;

[0156] The wheel frame 131 serves as the support structure for the rear wheel assembly. Its top is fixed to the lower end of the lightweight mobile frame 1 via bolts through the side wing plate 132. This installation method not only ensures the sturdiness of the wheel frame 131 but also facilitates disassembly or adjustment when needed. The rear wheel 133 is located inside the wheel frame 131. The diameter of the rear wheel 133 is smaller than that of the front wheel 12, which allows the device to maintain a low center of gravity during movement and improves overall stability. The limiting block 134 is located between the side wing plate 132 and the lightweight mobile frame 1. As a limiting component for the rear wheel assembly, the limiting block 134 adjusts the lateral spacing of the wheel frame 131. The design of the adjustable rear wheel assembly 13 and the front wheel 12 form a four-point support system, which effectively improves the lateral stability of the device.

[0157] A topdressing method for alfalfa planting topdressing device includes the following steps:

[0158] S1, Terrain Scan: Infrared LiDAR 14 scans the terrain of the work area and generates elevation compensation parameters;

[0159] S2, Multimodal Detection:

[0160] The rotation of the front wheel 12 triggers the gamma-ray sensor 25 to scan deep soil nutrients;

[0161] Electrochemical chip 26 contacts the soil to obtain ion concentration;

[0162] Microwave moisture meter 28 suspended scanning of surface moisture distribution;

[0163] Multispectral probe 27 collected the reflectance spectrum of alfalfa canopy;

[0164] S3, Data Fusion: Integrates topographic data, soil nutrients, ion concentration, moisture distribution, and canopy spectrum to generate fertilizer formulas;

[0165] S4, Dynamic Adjustment:

[0166] Adjust the opening degree of the control valves in each storage chamber 31 according to the fertilizer formula;

[0167] The lateral spray angle of the topdressing nozzle 33 is adjusted based on the canopy spectral density.

[0168] The circulating spraying speed of the topdressing nozzle 33 is adjusted based on the terrain elevation compensation parameters;

[0169] S5, Periodic Verification: After every K laps, verify the uniformity of fertilizer coverage and calibrate the test data.

[0170] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0171] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A topdressing device for alfalfa planting, characterized in that, include: The lightweight mobile frame (1) has a connector (11) for connecting to the power end, a front wheel (12) and an infrared laser radar (14) at the front end, and an adjustable rear wheel set (13) at the rear end. A multimodal detection unit (2) is integrated into the front wheel (12). The detection surface of the multimodal detection unit (2) and the scanning direction of the infrared lidar (14) form a spatially orthogonal arrangement, including: A rolling-triggered gamma-ray sensor (25) periodically emits rays as the front wheel (12) rotates; The contact-type electrochemical chip (26) directly contacts the soil to obtain ion concentration; A non-contact multispectral probe (27) was used to simultaneously acquire the reflectance spectrum of alfalfa canopy. A non-contact microwave moisture meter (28) scans surface moisture in mid-air. The fertilizer storage tank (3) is fixed on the lightweight mobile frame (1) and has multiple independent storage chambers (31). Each storage chamber (31) is connected to the topdressing nozzle (33) through the conveying pipe (32). The topdressing nozzle (33) is installed on both sides of the lightweight mobile frame (1) through the angle adjustment frame (4). Among them, the frame length L and the circumference C of the front wheel (12) satisfy: K is 3, 4, 5 or 6. Each time the front wheel (12) rotates K times, a detection and fertilization cycle is completed. Based on the fusion data of the multimodal detection unit (2), the fertilizer output ratio of each storage chamber (31) and the angle of the topdressing nozzle (33) are dynamically adjusted.

2. The alfalfa planting topdressing device according to claim 1, characterized in that: The front wheel (12) includes symmetrically arranged wheel bodies (121). The wheel bodies (121) are bolted to the front end of the lightweight mobile frame (1) by a fixing bracket (122). The wheel bodies (121) are fixedly connected by a connecting shaft (123). The multimodal detection unit (2) is fixed on the connecting shaft (123).

3. The alfalfa planting topdressing device according to claim 2, characterized in that: The multimodal detection unit (2) includes: The main detection shaft (21) is rigidly fixed to the connecting shaft (123), and the main detection shaft (21) is provided with a first mounting platform (211). The secondary detection shaft (22) is mounted on the lightweight mobile frame (1) via a buffer connection mechanism (23), and a second mounting platform (221) is provided on the secondary detection shaft (22). Synchronous transmission assembly (24) mechanically connects the main detection shaft (21) and the auxiliary detection shaft (22). The gamma-ray sensor (25) and electrochemical chip (26) are embedded in the first mounting platform (211), and the multispectral probe (27) and microwave moisture meter (28) are embedded in the second mounting platform (221).

4. The alfalfa planting topdressing device according to claim 3, characterized in that: The buffer connection mechanism (23) includes: Axle seat (231) is welded and fixed to the bottom of the lightweight mobile frame (1); The lifting block (232) is slidably disposed in the vertical groove of the bearing seat (231); The elastic element (233) abuts against the top of the bearing seat (231) at its upper end and against the upper surface of the lifting block (232) at its lower end; The grounding wheel (234) is fixed to the bottom of the lifting block (232) by bolts. The diameter of the grounding wheel (234) is smaller than the diameter of the front wheel (12).

5. The alfalfa planting topdressing device according to claim 3, characterized in that: The synchronous transmission assembly (24) includes: The drive wheel (241) is keyed to the main detection shaft (21); Driven wheel (242) is keyed to secondary detection shaft (22); Synchronous belt (243) meshes with driving pulley (241) and driven pulley (242); Tension regulator (244), consisting of: A movable tensioning pulley (244a) presses against the outer surface of the timing belt (243); The electric telescopic cylinder (244b) is fixed to the side wall of the lightweight mobile frame (1) by means of the bent rod fixing seat (244d), and drives the movable tension wheel (244a) to move along the direction of the vertical synchronous belt (243); Tension sensor (244c) detects the tension of synchronous belt (243) in real time and feeds it back to the control system; Among them, the axis of the tension wheel (244a) is parallel to the axes of the driving wheel (241) and the driven wheel (242), and the three are arranged in an isosceles triangle.

6. The alfalfa planting topdressing device according to claim 1, characterized in that: The fertilizer storage tank (3) includes: An integrated tank (30) has several partitions (34) evenly distributed inside. The partitions (34) divide the integrated tank (30) into multiple storage chambers (31). Each partition (34) consists of two mirror-symmetrically arranged baffles, with an air-isolated cavity (341) formed between the baffles. Each storage chamber (31) includes: The nitrogen fertilizer storage chamber (311) is provided with a nitrogen fertilizer inlet (311a) and a nitrogen exhaust port (311b) at the top, and a nitrogen concentration sensor (311c) is integrated inside. The inner wall is lined with PTFE (311d). The phosphorus and potassium fertilizer storage chamber (312) has a phosphorus and potassium fertilizer inlet (312a) at the top, an integrated magnetic stirrer (312b) inside, and a heat-insulating jacket (312c) on the side wall. The micro-fertilizer storage chamber (313) is provided with a micro-fertilizer inlet (313a) and a nitrogen gas filling port (313b) at the top, and is covered with a black HDPE light-shielding film (313c). The organic fertilizer storage chamber (314) has an organic fertilizer inlet (314a) at the top and integrates a temperature control plate (314b) and a dissolved oxygen probe (314c) inside.

7. The alfalfa planting topdressing device according to claim 1, characterized in that: The angle adjustment bracket (4) includes: A fixed seat (41) is provided on the side wall of the lightweight mobile frame (1); The lateral movement component (42) drives the first clamp (43) to move laterally; The longitudinal moving component (44) drives the second clamp (45) to move longitudinally; The top dressing nozzle (33) is respectively attached to the first clamp (43) and the second clamp (45) at both ends.

8. The alfalfa planting topdressing device according to claim 7, characterized in that: The lateral movement component (42) includes: The first servo motor (421) is bolted to the transverse groove of the mounting base (41); The threaded rod (422) is coaxially connected to the output end of the first servo motor (421); The first support rod (423) has a fixed threaded slider (424) at its lower end that engages with the threaded rod (422), and its upper end is movably connected to the bottom of the first clamp (43) via a ball joint; The longitudinal movement component (44) includes: The second servo motor (441) is bolted to the mounting base (41). The crankshaft (442) is keyed to the output of the second servo motor (441); Connecting rod (443), one end is hinged to the crank disc (442) at an eccentric position; The second support rod (444) has its lower end slidably connected to the guide rod (446) via the guide slider (445), and its upper end is movably connected to the bottom of the second clamp (45) via the ball joint; Linkage rod (447) fixes the side wall of the second support rod (444) and its end is hinged to the connecting rod (443).

9. The alfalfa planting topdressing device according to claim 3, characterized in that: The adjustable rear wheel assembly (13) includes: The wheel frame (131) is bolted to the lower end of the lightweight mobile frame (1) via side wing plates (132); The rear wheel (133) is located inside the wheel frame (131), and its diameter is smaller than that of the front wheel (12) and larger than that of the ground wheel (234); A limiting stop (134) is provided between the side wing plate (132) and the lightweight mobile frame (1).

10. The topdressing method of the alfalfa planting topdressing device according to any one of claims 1-9, characterized in that, Includes the following steps: S1, Terrain Scan: Infrared lidar (14) scans the terrain of the work area and generates elevation compensation parameters; S2, Multimodal Detection: The rotation of the front wheel (12) triggers the gamma-ray sensor (25) to scan deep soil nutrients; Electrochemical chip (26) contacts soil to obtain ion concentration; Microwave moisture meter (28) performs suspended scanning of surface moisture distribution; A multispectral probe (27) was used to collect the reflectance spectrum of alfalfa canopy; S3, Data Fusion: Integrates topographic data, soil nutrients, ion concentration, moisture distribution, and canopy spectrum to generate fertilizer formulas; S4, Dynamic Adjustment: Adjust the opening degree of the control valve of each storage chamber (31) according to the fertilizer formula; The lateral spray angle of the topdressing nozzle (33) is adjusted based on the canopy spectral density; Adjust the circulation spraying speed of the topdressing nozzle (33) based on the terrain elevation compensation parameter; S5, Periodic Verification: After every K laps, verify the uniformity of fertilizer coverage and calibrate the test data.

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