Precise positioning rice transplanting method and system

Abstract

The invention relates to the technical field of rice transplanting, in particular to a precise positioning rice transplanting method and system.The turning radius smaller than or equal to 2 m is achieved through a full-hydraulic four-wheel independent driving module, torque is distributed in real time based on the mud foot depth, and the stability of a deep mud field is kept through intelligent suspension; meanwhile, sensor data is used for controlling lifting of an auxiliary wheel, when a three-dimensional tilt angle sensor detects that the roll angle is larger than or equal to 15 degrees, an audible and visual alarm is triggered, the speed is automatically reduced to be smaller than or equal to 0.5 m / s, and in the process, a rice transplanting mechanism is accurately controlled to complete rice seedling taking, rice seedling separating and rice transplanting actions at the depth of 3-5 cm through an HST stepless speed change mechanism within the speed range of 0.2-4 m / s; through the full-hydraulic four-wheel independent driving module and the liftable auxiliary wheel mechanism, power distribution and grounding pressure are adjusted, so that the rice transplanter can stably run in a deep muddy foot field with the muddy foot depth exceeding 40 cm, the risk of machine sinking is effectively reduced, and the operation continuity and efficiency are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of rice transplanting, and in particular to a method and system for accurately positioning rice transplanting. Background Art

[0002] In mechanized rice planting operations, the passability and operational stability of the power chassis in deep muddy fields are key technical challenges. The design and configuration of the existing power chassis of rice transplanters used in paddy fields are mainly aimed at paddy fields with general mud depths. These chassis systems can meet basic operational requirements under normal conditions.

[0003] When operating in deep muddy fields, the risk of existing chassis getting stuck increases significantly. Once stuck, the chassis often finds it difficult to get out of the jam by relying on its own power. This is mainly because the excessively deep mud leads to uneven ground pressure distribution and a significant decrease in adhesion. Conventional driving and escape strategies are difficult to achieve the expected results under such extremely soft and low-bearing-capacity surface conditions. This frequent jamming and escape difficulty problem not only seriously hinders the continuity and efficiency of operations, but also increases the risk of equipment damage and operational safety.

[0004] Therefore, in response to the problem that the chassis is easy to sink and difficult to escape during operations in the above-mentioned deep muddy fields, the present invention proposes a method and system for accurately positioning rice transplanting. By integrating a new chassis system and transplanting method with fully hydraulic four-wheel independent drive, intelligent auxiliary wheel lifting and lowering, adaptive suspension adjustment and rollover warning technology, the transplanter's ability to prevent sinking and escape, driving stability and operating safety in muddy fields deeper than 40 cm are improved. Summary of the Invention

[0005] In order to overcome the problem that the chassis of the existing device is easy to sink and difficult to get out when operating in deep muddy fields, the present invention proposes a method and system for accurately positioning rice transplanting.

[0006] The technical solution of the present invention is: a method for accurately positioning rice transplanting, comprising the following steps: S1, uses a fully hydraulic four-wheel independent drive module to drive the transplanter chassis, and achieves a turning radius of ≤2m through four-wheel differential steering control; S2 distributes four-wheel torque in real time based on mud depth, maintaining chassis stability in fields with mud depth ≥ 400mm through the intelligent suspension system; S3, based on the data from the distance sensor and humidity sensor, controls the raising and lowering of the auxiliary wheels of the rear wheels; S4, based on the data of the three-dimensional tilt sensor, monitors the vehicle body tilt angle in real time. If the roll angle is ≥15°, it triggers an audible and visual alarm and automatically reduces the speed to ≤0.5m / s; S5, within the range of 0.2-4m / s, the HST continuously variable transmission mechanism controls the transplanting mechanism to complete the actions of taking, separating and transplanting seedlings, and inserts the seedlings into the mud layer to a depth of 3-5cm.

[0007] Preferably, the differential steering includes independently controlling the speed of the four wheels through a hydraulic motor, while monitoring the tire slip rate in real time and distributing torque using a PID control algorithm. When it is detected that the depth of a single wheel sinks beyond a threshold, the torque output difference of the other wheel is automatically increased to 1.5-2 times to form a forced escape torque.

[0008] Preferably, the suspension adjustment includes the use of a three-stage adjustable shock absorber linked with a hydraulic cylinder, real-time detection of surface undulations through a field laser scanner, and automatically starting the hydraulic pump to lift the chassis to 500mm when the ground clearance is less than 400mm, automatically switching to low damping mode in hard bottom areas and switching to high damping mode in deep mud areas.

[0009] Preferably, the lifting and lowering of the auxiliary wheel is performed by an electric push rod, and the response time is ≤0.5s.

[0010] Preferably, the auxiliary wheel control includes lowering the auxiliary wheel when the mud foot depth is greater than 40 cm or the soil shear strength is less than 15 kPa. The auxiliary wheel adopts a honeycomb aluminum floating plate to reduce the ground pressure to 5-8 kPa, and the wheelbase of the auxiliary wheel can be adjusted within the range of 1000-1200 mm.

[0011] As a preferred embodiment, a precise positioning rice transplanting system includes: Fully hydraulic four-wheel independent drive module, used to independently control the speed of each wheel through hydraulic motors to achieve differential steering; Paddy field wheel with optimized tooth shape, used to increase the contact area to 0.2㎡ and the tooth inclination angle is 20°±2°; Intelligent suspension system, used to dynamically adjust the ground clearance to 400-500mm according to the undulations of the field surface; The rear wheel can be raised and lowered with auxiliary wheel mechanism, which is used to deploy when the mud foot depth is greater than 40cm to reduce the ground pressure; Rollover detection and warning module, used to trigger audible and visual alarms and activate the braking system when the vehicle body roll angle is greater than 15°; The rice seedling transplanting module is used to complete the rice seedling removal, separation and transplanting operations; The central controller is used to process sensor data and coordinate the actions of the HST continuously variable transmission and various actuators.

[0012] Preferably, the fully hydraulic four-wheel independent drive unit comprises four sets of hydraulic motors, each set of hydraulic motors independently drives one tire, the maximum output torque of the hydraulic motors is ≥800 N·m, and the system pressure is set to 20-25 MPa.

[0013] Preferably, the tooth-profile optimized paddy field wheel includes 24 trapezoidal teeth, the anti-mud adhesion coating on the spoke surface is a polyurethane-based composite material, 6 axial drainage channels with a diameter of 10 mm are provided inside the hub, and wear-resistant carbide strips are welded on the outer circumference of the wheel rim.

[0014] Preferably, the rear wheel liftable auxiliary wheel mechanism includes a humidity sensor, which automatically lowers the auxiliary wheel to disperse gravity when the soil moisture content is greater than 60%.

[0015] Preferably, the anti-rollover detection and warning module includes a three-dimensional tilt sensor, a warning processor and an automatic braking unit. The three-dimensional tilt sensor adopts gyroscope and accelerometer fusion detection. The warning processor calculates the real-time rollover risk index through fuzzy PID algorithm. When the roll angle is greater than 15°, the cab sound and light alarm is activated. When the roll angle is greater than 20°, the automatic braking unit cuts off the HST continuously variable transmission power output through the clutch and triggers the parking hydraulic brake.

[0016] Beneficial effects of the present invention: The present invention dynamically adjusts the power distribution and ground contact pressure through a fully hydraulic four-wheel independent drive module and a liftable auxiliary wheel mechanism, enabling the rice transplanter to stably travel in deep mud fields with a mud foot depth exceeding 40 cm, thereby effectively reducing the risk of the machine getting stuck and ensuring operation continuity and efficiency. At the same time, when one side of the tire gets stuck in the mud, the system automatically increases the torque output of the tire on the other side, thereby forming a moment of forced escape. Combined with the liftable auxiliary wheel to disperse gravity, the self-rescue ability of the rice transplanter in extremely soft mud fields is significantly improved, reducing the need for manual rescue.

[0017] The present invention adopts four-wheel differential steering control to make the turning radius ≤2m, thereby improving the maneuverability of field operations. At the same time, the adaptive dynamic transmission system adjusts the torque distribution in real time to suppress tire slippage, ensure the driving stability of the chassis in deep mud environments, and adjusts the suspension height and shock damping in real time based on the undulations of the field surface, so that the chassis ground clearance is always ≥400mm. It automatically switches to the optimal mode in hard bottom and deep mud areas, reducing the risk of bumps and sinking and improving operation stability.

[0018] The vehicle body posture is monitored in real time through a three-dimensional tilt sensor. When the roll angle is ≥15°, an audible and visual alarm is triggered and the vehicle automatically decelerates. When the roll angle is >20°, the power is cut off and the vehicle brakes are applied, thereby significantly reducing the risk of rollover accidents and protecting the safety of personnel and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 What is shown is a schematic diagram of the workflow of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0021] See also Figure 1 The present invention provides an embodiment: a method for accurately positioning rice transplanting, comprising the following steps: First, the transplanter chassis is driven by a fully hydraulic four-wheel independent drive module, and the four-wheel differential steering control is used to achieve a small turning radius of ≤2m. During the journey, the four-wheel torque is dynamically distributed based on the real-time detection of the mud foot depth. The intelligent suspension system maintains the driving stability of the chassis in mud fields ≥400mm deep. At the same time, the lifting and lowering of the rear wheel auxiliary wheels are intelligently controlled according to the data of the humidity sensor. When the mud foot depth is greater than 40cm or the soil moisture content is greater than 60%, the auxiliary wheels are automatically lowered to disperse gravity. The body inclination angle is continuously monitored during travel. When the roll angle is ≥15°, an audible and visual alarm is triggered and the speed is automatically reduced to ≤0.5m / s. Finally, within the continuously variable speed range of 0.2-4m / s, the HST continuously variable speed mechanism is used to accurately control the transplanting mechanism to complete the seedling removal, separation and transplanting actions, thereby ensuring that the seedlings are inserted into the mud layer to a depth of 3-5cm.

[0022] Furthermore, four-wheel independent drive and differential steering significantly improve the passability and steering flexibility in deep mud fields, while the adaptive torque distribution and intelligent lifting of the auxiliary wheels can effectively prevent the chassis from sinking and enhance its ability to escape. At the same time, real-time tilt angle monitoring and automatic speed reduction mechanism greatly reduce the risk of rollover. The coordinated control of the continuously variable transmission and the planting mechanism ensures the unity of working efficiency and transplanting accuracy. The present invention as a whole achieves the coordinated improvement of high passability, high safety and high working quality in deep mud field environment.

[0023] The differential steering includes independently controlling the speed of the four wheels through a hydraulic motor, while monitoring the tire slip rate in real time and distributing torque using a PID control algorithm. When it is detected that the depth of one side wheel sinks beyond a threshold, the torque output difference of the other side wheel is automatically increased to 1.5-2 times to form a forced escape torque.

[0024] Furthermore, four sets of independently controlled hydraulic motors drive the four tires respectively. The maximum output torque of each set of hydraulic motors is set to ≥800N·m and the system pressure is maintained in the range of 20-25MPa. During the steering process, the central controller collects the speed signal of each tire in real time and calculates the slip rate. When it is detected that one side of the tire is stuck in the mud and the slip rate exceeds the set threshold, the system immediately activates the PID control algorithm, dynamically adjusts the flow distribution of the hydraulic motor, and increases the torque output on the other side to 1.5-2 times that of the stuck side, forming a forced escape torque difference. At the same time, the tire on the stuck side automatically switches to a high-frequency intermittent drive mode to reduce continuous slip. The torque difference maintenance time is adaptively adjusted according to the tire sinking depth until the slip rate returns to a safe range. During this process, the four-wheel independent drive system communicates with the three-dimensional inclination sensor in real time via the CAN bus to ensure that the torque distribution process does not affect the stability of the vehicle body. Ultimately, without adding additional escape devices, the rice transplanter can be autonomously escaped from a single-sided deep-stuck state through intelligent adjustment of the power system alone.

[0025] Furthermore, the rice transplanter chassis is equipped with a suspension system with three-stage adjustable shock absorbers and hydraulic cylinder linkage. The surface undulation data is collected in real time through the field laser scanner and transmitted to the central controller. When the ground clearance is detected to be less than 400mm, the system immediately starts the hydraulic pump to lift the chassis to a safe height of 500mm. During the lifting process, the shock absorber automatically switches to high damping mode to suppress body shaking. When operating in the hard bottom area, the system automatically switches to low damping mode after recognizing that the surface firmness meets the standard to improve driving smoothness, while in deep mud areas, it maintains high damping mode to enhance chassis stability. The suspension height adjustment adopts closed-loop control, and the ground clearance data is fed back in real time through the ranging sensors installed at the four corners of the chassis to ensure that the adjustment accuracy error does not exceed ±10mm. At the same time, the system is equipped with a manual priority mode, which can forcibly lock the suspension height when the automatic adjustment fails. The suspension system not only effectively avoids the risk of chassis bottoming out through dynamic adjustment, but also significantly improves the ride comfort and operational stability when operating in deep mud fields.

[0026] Furthermore, the auxiliary wheel lifting mechanism uses an electric push rod to lift it. The push rod has a rated thrust of ≥3000N and a stroke of 200mm. The control system receives signals from the distance sensor and soil moisture sensor in real time. When the mud foot depth is detected to be >40cm or the soil moisture content is >60%, the central controller immediately sends a PWM control signal to the electric push rod to drive the push rod to complete the rapid extension of the auxiliary wheel from the retracted position to the working position within 0.5s. During the lifting process, the Hall sensor installed in the push rod provides real-time feedback of position information to form a closed-loop control, thereby ensuring that the final positioning accuracy of the auxiliary wheel reaches ±2mm. In an emergency, the push rod action can be directly controlled by the button in the cab. The system adopts dual-channel CAN bus communication and redundant power supply design to ensure that the lifting and lowering commands can be reliably executed even in complex field environments. This rapid response mechanism significantly improves the rice transplanter's ability to escape immediately in sudden deep-stuck situations.

[0027] A precise positioning rice transplanting system, comprising: Fully hydraulic four-wheel independent drive module, used to independently control the speed of each wheel through hydraulic motors to achieve differential steering; Paddy field wheel with optimized tooth shape, used to increase the contact area to 0.2㎡ and the tooth inclination angle is 20°±2°; Intelligent suspension system, used to adjust the ground clearance to 400-500mm according to the undulations of the field surface; The auxiliary wheel mechanism can be raised and lowered to reduce the ground pressure when the mud foot depth is greater than 40cm; Rollover detection and warning module, used to trigger audible and visual alarms and activate the braking system when the vehicle body roll angle is greater than 15°; The rice seedling transplanting module is used to complete the rice seedling removal, separation and transplanting operations; The central controller is used to process sensor data and coordinate the actions of the HST continuously variable transmission and various actuators.

[0028] The tooth-profile optimized paddy field wheel includes 24 trapezoidal teeth, the anti-mud adhesion coating on the spoke surface is a polyurethane-based composite material, 6 axial drainage channels with a diameter of 10 mm are arranged inside the hub, and wear-resistant carbide strips are welded on the outer circumference of the wheel rim.

[0029] The liftable auxiliary wheel mechanism includes a humidity sensor and a distance sensor. When the mud foot depth is greater than 40 cm or the soil moisture content is greater than 60%, the auxiliary wheel is automatically lowered to disperse gravity.

[0030] The anti-rollover detection and warning module includes a three-dimensional tilt sensor, a warning processor and an automatic braking unit. The three-dimensional tilt sensor uses a gyroscope and an accelerometer for fusion detection. The warning processor calculates the real-time rollover risk index through a fuzzy PID algorithm. When the roll angle is greater than 15°, the cab sound and light alarm is activated. When the roll angle is greater than 20°, the automatic braking unit cuts off the HST continuously variable transmission power output through the clutch and triggers the parking hydraulic brake.

[0031] The system uses a three-dimensional tilt sensor to collect vehicle body posture data in real time, and calculates the tilt angles of the X / Y / Z axes through a sensor fusion algorithm with a measurement accuracy of ±0.1°. The early warning processor runs a fuzzy PID control algorithm to calculate the real-time rollover risk index based on the tilt angle data, driving speed and ground slope. When a roll angle of >15° is detected, the sound and light alarm in the cab is immediately triggered, thereby triggering a 120dB buzzer and a flashing red LED, and sending a deceleration command to the HST continuously variable transmission via the CAN bus, thereby limiting the vehicle speed to a safe range. If the roll angle continues to increase to >20°, the system immediately cuts off the power output of the clutch and activates the parking hydraulic brake, while completing the hydraulic locking of the four wheels within 0.3 seconds.

[0032] Furthermore, the present invention provides an embodiment of a conventional deep mud field operation scenario: When the rice transplanter enters a paddy field with a mud depth of 45cm, the four-wheel independent drive system monitors in real time that the slip rate of the right rear wheel exceeds the preset threshold of 15%. The central controller immediately starts the differential escape program: first, based on the PID control algorithm, a system pressure of 20MPa is output to the left front wheel hydraulic motor to increase its torque value from the base 600N·m to 1080N·m, thereby forming a counterclockwise forced escape torque. At the same time, the right rear wheel is switched to intermittent drive mode, thereby effectively reducing the mud agitation caused by continuous slippage. While the power system is adjusting, after the rear auxiliary wheel mechanism receives the 45.3cm measured data sent by the mud depth sensor, the electric push rod completes the 120mm stroke extension action within 0.48 seconds, so that the two sets of 400mm diameter honeycomb aluminum auxiliary wheels are fully in contact with the ground, expanding the vehicle's ground contact area by 35% and increasing the ground pressure. The force dropped from 12kPa to 7.8kPa. At this time, the three-dimensional tilt sensor detected that the vehicle body tilted 12.3° to the left front due to the right rear wheel's escape. The anti-rollover detection and warning module activated the sound and light alarm, but the brake trigger threshold of 15° was not reached. The HST continuously variable transmission maintained the current operating speed of 2.1m / s. The suspension system, based on the field surface data obtained by the laser scanner, controlled the hydraulic cylinder to increase the ground clearance of the middle chassis from the initial 380mm to 452mm. At the same time, the shock absorber damping coefficient was adjusted to 18N·s / mm to suppress vehicle body shaking. Throughout the process, the transplanting mechanism maintained a planting depth of 4.1±0.2cm within the speed fluctuation range of 2.03-2.15m / s through the speed-depth coupling control algorithm, thereby ensuring that the angle of the seedlings entering the mud was always controlled within the ideal range of 88°-92°.

[0033] Furthermore, the present invention provides an embodiment for a sudden escape scenario: When the right rear wheel suddenly sank into a 50cm-deep mud puddle, the trapped vehicle side switched to high-frequency pulse drive mode (100ms drive / 50ms stop). At the same time, the pressure of the hydraulic motors of the left front, left rear and right front wheels was synchronously increased to 22MPa, and the output torque reached 1200N·m, thus forming a powerful compound escape torque. At the same time, the two sets of rear auxiliary wheels were fully deployed within 0.5 seconds, and the honeycomb floating disc expanded the vehicle's ground contact area to 0.35㎡, and the ground pressure dropped sharply from 15kPa to 6kPa. The anti-rollover detection and warning module detected in real time that the vehicle body had an 18.2° roll due to unilateral restriction, immediately triggering an audible and visual alarm and limiting the vehicle speed to 0.3m / s via the CAN bus. At this time, the suspension system automatically switched to ultra-high damping mode (25N·s / mm), and the hydraulic cylinder lifted the chassis to a safe height of 480mm. After 8 seconds of torque optimization distribution, the vehicle successfully escaped. During this period, the transplanting mechanism automatically disconnected the power transmission through the electromagnetic clutch, avoiding damage to the seedling removal mechanism under abnormal working conditions.

[0034] This embodiment verifies the system's collaborative capabilities in power reorganization, emergency support, and safety protection in extreme vehicle-stuck situations, and the response times of all subsystems meet design specifications.

[0035] Furthermore, the present invention provides an embodiment for an extremely slippery ridge turning scenario: When turning on a ridge with a soil moisture content of 70%, the system automatically calculates the optimal speed difference between each wheel, thereby precisely controlling the turning radius to 1.8m. When the outer wheel increases the probability of slipping due to the load, the system controls the outer wheel torque to increase by 30% and temporarily reduces the inner wheel speed. At the same time, the anti-rollover detection and warning module maintains the vehicle body inclination angle within a safe range of 10° in real time. The auxiliary wheels automatically adjust the deployment range according to the steering angle. The lateral offset of the vehicle body does not exceed 15cm during the entire steering process.

[0036] When the rice transplanter entered a slippery field ridge with a soil moisture content of 70% at a speed of 2.4 m / s, the system calculated the target speeds for all four wheels in real time: the left front wheel accelerated to 58 rpm, the right front wheel slowed to 42 rpm, and the rear wheels maintained a base speed of 52 rpm, thereby precisely achieving a turning radius of 1.78 m. During the turn, load transfer caused the slip rate of the outer right front wheel to increase to 18%. The system immediately increased the torque of the right front wheel by 30% to 780 N·m and briefly reduced the speed of the inner left front wheel by 15% to balance the driving torque. The rollover detection and warning module, integrating data from the gyroscope and accelerometer, controlled the vehicle's roll angle within a safe range of 9.8°-10.2° in real time. When the instantaneous roll reached 11.5°, the steering correction torque was preemptively activated. The outer auxiliary wheel automatically extended by an additional 20 mm based on the steering angle, increasing its effective support area by 25%, thus forming a reinforced rollover structure.

[0037] During the entire steering process, the lateral offset of the vehicle body was verified to be 14.7cm by a laser rangefinder, and the transplanting mechanism maintained a stable transplanting depth of 3-5cm within the speed fluctuation range of ±0.15m / s, verifying the system's ability to maintain steering accuracy under extreme adhesion conditions.

[0038] Through the above steps, the power distribution and ground pressure are dynamically adjusted through the fully hydraulic four-wheel independent drive module and the liftable auxiliary wheel mechanism, so that the rice transplanter can stably travel in deep mud fields with a mud depth of more than 40 cm, thereby effectively reducing the risk of the machine getting stuck, thereby ensuring operation continuity and efficiency, and solving the problem that the chassis of existing devices is easy to get stuck and difficult to get out when operating in deep mud fields.

[0039] The above are merely preferred embodiments of the present invention and do not limit the present invention in any other form. Any technician familiar with the present invention may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for accurately positioning rice transplanting, characterized in that: The following steps are included: S1, uses a fully hydraulic four-wheel independent drive module to drive the transplanter chassis, and achieves a turning radius of ≤2m through four-wheel differential steering control; S2 distributes four-wheel torque in real time based on mud depth, maintaining chassis stability in fields with mud depth ≥ 400mm through the intelligent suspension system; S3, based on the data from the distance sensor and humidity sensor, controls the raising and lowering of the auxiliary wheels of the rear wheels; S4, based on the data of the three-dimensional tilt sensor, monitors the vehicle body tilt angle in real time. If the roll angle is ≥15°, it triggers an audible and visual alarm and automatically reduces the speed to ≤0.5m / s; S5, within the range of 0.2-4m / s, the HST continuously variable transmission mechanism controls the transplanting mechanism to complete the actions of taking, separating and transplanting seedlings, and inserts the seedlings into the mud layer to a depth of 3-5cm.

2. The method for accurately positioning rice transplanting according to claim 1, characterized in that: The differential steering includes independently controlling the speed of the four wheels through a hydraulic motor, while monitoring the tire slip rate in real time and distributing torque using a PID control algorithm. When it is detected that the depth of one side wheel sinks beyond a threshold, the torque output difference of the other side wheel is automatically increased to 1.5-2 times to form a forced escape torque.

3. The method for accurately positioning rice transplanting according to claim 1, characterized in that: The suspension adjustment includes the use of a three-stage adjustable shock absorber linked with a hydraulic cylinder, and real-time detection of surface undulations through a field laser scanner. When the ground clearance is less than 400mm, the hydraulic pump is automatically started to lift the chassis to 500mm, and it automatically switches to low-damping mode in hard bottom areas and to high-damping mode in deep mud areas.

4. The method for accurately positioning rice transplanting according to claim 1, characterized in that: The lifting and lowering of the auxiliary wheel is performed by an electric push rod, and the response time is ≤0.5s.

5. The method for accurately positioning rice transplanting according to claim 1, characterized in that: The auxiliary wheel control includes lowering the auxiliary wheel when the mud foot depth is greater than 40cm or the soil moisture content is greater than 60%. The auxiliary wheel uses a honeycomb aluminum floating plate to reduce the ground pressure to 5-8kPa, and the wheelbase of the auxiliary wheel can be adjusted within the range of 1000-1200mm.

6. A precise positioning rice transplanting system, a precise positioning rice transplanting method according to claims 1-5, characterized in that: Includes: Fully hydraulic four-wheel independent drive module, used to independently control the speed of each wheel through hydraulic motors to achieve differential steering; Paddy field wheel with optimized tooth shape, used to increase the contact area to 0.2㎡ and the tooth inclination angle is 20°±2°; Intelligent suspension system, used to adjust the ground clearance to 400-500mm according to the undulations of the field surface; The auxiliary wheel mechanism can be raised and lowered to reduce the ground pressure when the mud foot depth is greater than 40cm; Rollover detection and warning module, used to trigger audible and visual alarms and activate the braking system when the vehicle body roll angle is greater than 15°; The rice seedling transplanting module is used to complete the rice seedling removal, separation and transplanting operations; The central controller is used to process sensor data and coordinate the actions of the HST continuously variable transmission and various actuators.

7. The precise positioning rice transplanting system according to claim 6, characterized in that: The fully hydraulic four-wheel independent drive unit includes four sets of hydraulic motors, each set of hydraulic motors independently drives one tire, the maximum output torque of the hydraulic motor is ≥800N·m, and the system pressure is set to 20-25MPa.

8. The precise positioning rice transplanting system according to claim 6, characterized in that: The tooth-profile optimized paddy field wheel includes 24 trapezoidal teeth, the anti-mud adhesion coating on the spoke surface is a polyurethane-based composite material, 6 axial drainage channels with a diameter of 10 mm are arranged inside the hub, and wear-resistant carbide strips are welded on the outer circumference of the wheel rim.

9. The precise positioning rice transplanting system according to claim 6, characterized in that: The liftable auxiliary wheel mechanism includes a humidity sensor and a distance sensor. When the mud foot depth is greater than 40 cm or the soil moisture content is greater than 60%, the auxiliary wheel is automatically lowered to disperse gravity.

10. The precise positioning rice transplanting system according to claim 6, characterized in that: The anti-rollover detection and warning module includes a three-dimensional tilt sensor, a warning processor and an automatic braking unit. The three-dimensional tilt sensor uses a gyroscope and an accelerometer for fusion detection. The warning processor calculates the real-time rollover risk index through a fuzzy PID algorithm. When the roll angle is greater than 15°, the cab sound and light alarm is activated. When the roll angle is greater than 20°, the automatic braking unit cuts off the HST continuously variable transmission power output through the clutch and triggers the parking hydraulic brake.

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