Agricultural machinery traction mechanism automatic docking device based on laser positioning and correction method

Abstract

The invention discloses an agricultural machinery traction mechanism automatic docking device based on laser positioning and a correction method, and solves the problems of easy interruption of field positioning, slow response and low cooperative efficiency of multiple agricultural machinery of an existing device. The device comprises an agricultural machine body, an agricultural tool traction frame, a multi-mode laser positioning assembly, a magnetorheological fluid driving assembly and a distributed control assembly. According to the method, the position is captured through laser positioning, attitude data output deviation is fused through an EKF algorithm, universal joint correction is driven, and one-master and three-slave parallel butt joint is supported. The device can realize continuous and reliable laser positioning of an agricultural machine and an agricultural implement traction mechanism under complex working conditions of field dust, straw shielding and the like, meanwhile, through magnetorheological fluid driving and dynamic posture fusion correction, the docking response speed is increased, parallel and cooperative docking of multiple agricultural implements can be supported, the total docking time is greatly shortened, manual intervention is reduced, and the docking efficiency is improved. The large-scale agricultural operation requirements are met.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery traction mechanism docking technology, and in particular to an automatic docking device and calibration method for agricultural machinery traction mechanisms based on laser positioning. Background Technology

[0002] As modern agriculture develops towards large-scale and intensive operations, the rapid and precise docking of agricultural machinery and implements has become a key factor in improving field operation efficiency. The docking efficiency of tractors with implements such as seeders and fertilizer applicators directly affects the entire operation cycle, including tillage, sowing, and fertilization. Currently, although automatic docking technology for agricultural machinery traction mechanisms has been initially applied, significant technical bottlenecks remain in areas such as adaptability to complex field conditions, docking response speed, and multi-machine collaboration efficiency, making it difficult to meet the demands of high-standard agricultural production. Specific problems are as follows:

[0003] Current automatic docking systems for agricultural machinery mostly employ a positioning scheme using a single-beam laser emitter and fixed photoelectric sensors. The core drawback of this approach is its poor anti-interference capability and inability to adapt to changes in the posture of the implements. On the one hand, dust and crop straw during field operations can easily obstruct the laser beam path, causing the sensor to fail to capture the light spot, resulting in a high rate of positioning interruption. Manual removal of obstructions is required before docking can be restarted, severely impacting the continuity of operations. On the other hand, implements are prone to tilting and pitching deviations when operating on undulating terrain. Fixed photoelectric sensors cannot dynamically adjust their receiving angle, causing the laser spot to easily deviate from the effective detection area of ​​the sensor, resulting in poor positioning accuracy. This, in turn, leads to misalignment between the traction pin and the traction hole, causing jamming or inability to insert.

[0004] Existing agricultural machinery docking actuators mostly rely on hydraulic or electric actuators. Both types of mechanisms suffer from slow response speed and inflexible attitude adjustment. Hydraulic actuators are affected by the viscosity and temperature sensitivity of hydraulic oil, resulting in a large response delay. They cannot adapt to the reversing docking speed of agricultural machinery (0.5-3 m / s) and are prone to misalignment of the traction pin and hole due to attitude adjustment lag. While electric actuators are not affected by hydraulic oil, the thrust adjustment is stepped and can only achieve linear movement in one direction, making it difficult to compensate for the three-dimensional attitude deviation of the implement. More importantly, existing technologies adopt a step-by-step mode of positioning, stopping, and correction. Positioning is completed first and the movement of the agricultural machinery is stopped before the actuator is started to adjust the attitude. During this process, the relative attitude of the agricultural machinery and implement is easily changed again due to ground vibration, resulting in a decrease in correction accuracy.

[0005] Currently, when multiple agricultural implements are connected in series, a sequential connection process is generally adopted. The first implement must be connected to the tractor first, then the laser positioning link is disconnected and the second implement is recalibrated, and so on. The total connection time for a single group of three implements exceeds 45 seconds, which cannot meet the high-efficiency operation requirements of large-scale planting bases. At the same time, subsequent implements only rely on their own positioning data and do not take into account the tilt and pitch deviations of the previous implements. This results in the need to compensate for the previous deviations when connecting subsequent implements, forming cumulative errors.

[0006] Therefore, the existing automatic docking technology for agricultural machinery traction mechanisms has significant shortcomings in three core dimensions: anti-interference positioning, rapid response execution, and multi-machine collaboration. There is an urgent need for a new technical solution that can adapt to complex field conditions, improve docking efficiency and accuracy, and support the parallel collaboration of multiple agricultural machines to meet the needs of modern large-scale agricultural operations. Summary of the Invention

[0007] One objective of this invention is to propose an automatic docking device and correction method for agricultural machinery traction mechanisms based on laser positioning. This invention can achieve continuous and reliable laser positioning of agricultural machinery and implement traction mechanisms under complex working conditions such as dust and straw obstruction in the field. At the same time, through magnetorheological fluid drive and dynamic attitude fusion correction, the docking response speed is improved. It can also support parallel and collaborative docking of multiple implements, significantly shortening the total docking time, reducing manual intervention, and adapting to the needs of large-scale agricultural operations.

[0008] An automatic docking device for agricultural machinery traction mechanism based on laser positioning according to an embodiment of the present invention includes agricultural machinery, agricultural implement traction frame, multimodal laser positioning component, dynamic attitude detection component, magnetorheological fluid drive component and distributed control component;

[0009] The agricultural machinery is fixed to the rear side with a traction end crossbeam. A traction pin hole is opened at the top of the rear side of the traction end crossbeam. A first electrical box is installed on the side wall of the crossbeam, and a second electrical box is installed on the side wall of the agricultural implement traction frame.

[0010] The multimodal laser positioning component includes a laser emitter and a laser receiver. The laser emitter is fixed to the top of the traction end crossbeam, and the laser receiver is fixed to the inside of the implement traction frame. The two are directly opposite each other along the docking direction of the agricultural machinery and the implement traction frame. The laser emitter has a built-in main laser generating module, two auxiliary laser generating modules, and a synchronous triggering module. The main laser generating module emits visible light laser, and the two auxiliary laser generating modules emit near-infrared polarized laser and are symmetrically distributed at 30° with the main laser generating module as the center. The synchronous triggering module is electrically connected to the agricultural machinery ECU via a CAN bus. The laser receiver has a built-in 3×3 pixel Si-PIN photodiode array, an adaptive gimbal mechanism, and a MEMS tilt angle detection module. The adaptive gimbal carries the photodiode array, and the MEMS tilt angle detection module is electrically connected to the gimbal drive motor.

[0011] The dynamic attitude detection component includes a traction end attitude detector and a traction end attitude detector. The traction end attitude detector is fixed in a first electrical box, and the traction end attitude detector is fixed in a second electrical box and close to the laser receiver. Both the traction end attitude detector and the traction end attitude detector integrate a MEMS gyroscope, a three-axis accelerometer, a BeiDou positioning module, and a data fusion module. The output terminals of the MEMS gyroscope, accelerometer, and BeiDou module are electrically connected to the input terminal of the data fusion module. After processing the data using an extended Kalman filter algorithm, the data fusion module is electrically connected to the distributed control component.

[0012] The magnetorheological fluid drive assembly is fixed directly below the implement traction frame and includes a magnetorheological fluid universal joint, an electric traction pin, and a force feedback detection module. The magnetorheological fluid universal joint is fixed below the implement traction frame by a U-shaped frame and has an internal excitation coil assembly and magnetorheological fluid. The excitation coil assembly is electrically connected to the distributed control assembly. One end of the electric traction pin is connected to the output shaft of the universal joint via a spline, and the other end has a tapered structure for insertion into the traction pin hole. The force feedback detection module is sleeved on the side wall of the electric traction pin and is electrically connected to the distributed control assembly.

[0013] The distributed control component includes a master controller and slave controllers. The master controller is fixed in the first electrical box, and its signal input terminal is electrically connected to the agricultural machinery ECU, the laser transmitter synchronous trigger module, and the traction end attitude detector via a CAN bus. Its signal output terminal communicates with the slave controllers via a laser networking link. The slave controller is fixed in the second electrical box, and its signal input terminal is electrically connected to the laser receiver gimbal motor, the traction end attitude detector, and the force feedback detection module via a CAN bus. Its signal output terminal is electrically connected to the magnetorheological fluid universal joint and the electric traction pin via wires. The master controller supports simultaneous communication with at least 3 slave controllers, realizing collaborative docking between one agricultural machine and multiple agricultural implements.

[0014] Furthermore, in the multimodal laser positioning component, the main laser generating module of the laser emitter outputs visible light laser with a wavelength of 650nm, and the two auxiliary laser generating modules output near-infrared polarized laser with a wavelength of 850nm, with the polarization directions orthogonally distributed. The 3×3 pixel Si-PIN photodiode array of the laser receiver has a single pixel size of 1mm×1mm and a response wavelength covering 600-900nm. The adaptive gimbal mechanism is driven by a two-phase 42-step motor with an adjustable step angle of 0.9° / 1.8°. The measurement range of the MEMS tilt angle detection module is ±45°.

[0015] Furthermore, in the dynamic attitude detection component, the MEMS gyroscope range of the traction end attitude detector and the traction end attitude detector is ±2000° / s, the zero bias stability is ≤5° / h, the three-axis accelerometer range is ±16g, the Beidou positioning module supports dual-frequency positioning, the sampling frequency of the data fusion module is 200Hz, and the state update frequency of the extended Kalman filter algorithm is consistent with the sampling frequency.

[0016] Furthermore, in the magnetorheological fluid drive assembly, the magnetorheological fluid built into the magnetorheological fluid universal joint has a viscosity ≤0.1 Pa·s under zero magnetic field; the excitation coil assembly is a double-winding structure wound with enameled copper wire, with 200 turns per winding; the electric traction pin conical structure has a taper of 1:10 and an effective insertion length of 50-80 mm; and the force feedback detection module uses a strain gauge force sensor with a measurement range of 0-5 kN.

[0017] Furthermore, in the distributed control component, the laser networking link adopts time-division multiple access communication mode with a communication rate of 10Mbps and supports an automatic reconnection mechanism.

[0018] Furthermore, both the first and second electrical boxes are made of die-cast aluminum alloy, and the U-shaped frame connection between the implement traction frame and the magnetorheological fluid drive assembly is fixed by seam welding.

[0019] A calibration method for an automatic docking device of an agricultural machinery traction mechanism based on laser positioning includes the following steps:

[0020] S1. Initialization and networking: After the agricultural machinery is started, the main controller is powered on and broadcasts a synchronization signal through the laser networking link. After each implement receives the signal from the controller, it performs self-tests on the laser receiver, magnetorheological fluid drive component, and attitude detector at the traction end. The results are fed back to the main controller through the CAN bus. The main controller assigns slave node IDs, determines the docking order of multiple implements, and establishes a distributed laser communication network.

[0021] S2. Multimodal laser coarse positioning: The main controller sends the main laser start command to the laser transmitter. After the visible light main laser is emitted, the laser receiver photodiode array captures the light spot and calculates the initial relative position. The MEMS tilt detection module collects the side tilt and pitch angles of the implement and drives the adaptive gimbal to adjust so that the light spot offset is <2mm.

[0022] S3, Dynamic attitude fusion for precise positioning: The main controller starts two near-infrared auxiliary lasers, and the laser receiver synchronously receives the main and auxiliary laser signals. The dynamic attitude detection component transmits the attitude data to the main controller. The main controller fuses the laser positioning and attitude data through an extended Kalman filter algorithm and outputs the X / Y / Z axis and three-dimensional angle deviation. If a single set of auxiliary lasers is blocked, it automatically switches to redundant positioning using the main laser, a single auxiliary laser, and attitude data.

[0023] S4. Magnetorheological fluid driven dynamic correction: The main controller sends instructions to the slave controller according to the deviation. The slave controller outputs excitation current. When the sideslip angle is >1mm, the lateral current is adjusted. When the pitch and roll angles are >0.5°, the longitudinal current is adjusted. The force feedback detection module monitors the contact force. When the force value is >1kN, the thrust is reduced and the universal joint angle is finely adjusted.

[0024] S5. Locking and Coordination Correction: After the electric traction pin is inserted into the traction pin hole to a depth of >90% and the force value is stable for 1 second, the controller sends a docking completion signal. The main controller sends a synchronization correction signal to the subsequent slave controllers. The subsequent implements pre-compensate for deviations based on the previous posture data to achieve parallel docking.

[0025] S6. Dynamic monitoring after docking: After docking is completed, the laser transmitter switches to low power operation, and the laser receiver continuously monitors the relative attitude deviation. When the deviation is >2mm, the main controller triggers secondary correction, and the slave controller controls the universal joint for fine adjustment.

[0026] Furthermore, in step S2, the main laser positioning distance covers the initial docking distance between the agricultural machinery and implements of 0.5-3m. The adaptive gimbal adjustment response time and the feedback frequency of the MEMS tilt detection module are consistent, both being 100Hz. During the adjustment process, the center of the light spot is always kept in the 3×3 pixel area of ​​the center of the photodiode array to avoid positioning interruption.

[0027] Furthermore, in step S3, under the redundant positioning mode, the main controller maintains a positioning accuracy of ≤3mm by increasing the weight of the centimeter-level precision data of the Beidou positioning module. If both sets of auxiliary lasers are blocked, the weight of the fusion of the main laser and attitude data is strengthened to trigger dual redundant positioning with an accuracy of ≤5mm, ensuring continuous docking.

[0028] Furthermore, in step S5, during the multi-farm machinery collaborative correction, the main controller's synchronization control error for each slave node is <1ms, the docking time for a single slave node is <5s, and the total docking time for the three slave nodes is <10s. After docking is completed, the electric traction pin locking torque is 20-30N·m, and the force feedback detection module continuously monitors the locking force. When the force value is <0.3kN, an alarm is triggered and the locking is re-engaged.

[0029] The beneficial effects of this invention are:

[0030] 1. This invention employs a multi-mode laser array consisting of a visible light main laser and a near-infrared polarized auxiliary laser, coupled with an adaptive gimbal equipped with a MEMS tilt detection module. The main laser is responsible for quickly capturing the initial docking position, while the two auxiliary lasers are symmetrically distributed at 30° and equipped with polarization filtering, which can penetrate field dust and straw interference. The adaptive gimbal dynamically adjusts the receiving angle of the 3×3 pixel Si-PIN photodiode array through a two-phase 42-stepper motor based on the tilt and pitch angles of the farm implements collected in real time by the MEMS module, ensuring that the laser spot always falls on the 3×3 pixel area in the center of the array. Therefore, it can effectively reduce the docking interruption rate and ensure stable and reliable positioning accuracy.

[0031] 2. In this invention, a magnetorheological fluid universal joint replaces the traditional hydraulic or electric push rod. The viscosity of the magnetorheological fluid changes in real time with the excitation coil current, with a response time of <0.05s. This allows for rapid adjustment of the docking angle and thrust. Simultaneously, the dynamic attitude detection component uses the EKF extended Kalman filter algorithm to integrate data from the MEMS gyroscope, triaxial accelerometer, and Beidou dual-frequency positioning to output the relative attitude deviation between the agricultural machinery and implements. This enables simultaneous positioning and correction, significantly improving the docking response speed. It can adapt to the reversing docking speed of agricultural machinery from 0.5-3m / s, avoiding traction pin jamming caused by response lag. Furthermore, the docking accuracy is greatly improved, and the success rate of inserting the electric traction pin into the traction pin hole on the first attempt is significantly increased.

[0032] 3. In this invention, a distributed control architecture is constructed. The main controller communicates with up to three slave controllers through a time-division multiple access laser network link, assigns slave node IDs and determines the docking order. After the first implement is docked, the main controller immediately sends the previous attitude data to the subsequent implements. The subsequent implements adjust their own attitude in advance based on the tilt and pitch deviations of the previous implements, realizing parallel docking. This greatly shortens the total docking time of multiple implements and improves efficiency. Moreover, the master and slave nodes can synchronously control errors, avoiding the accumulation of deviations when multiple agricultural machines are connected in series. Attached Figure Description

[0033] 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:

[0034] Figure 1 This is a schematic diagram of the overall structure of an automatic docking device for agricultural machinery traction mechanism based on laser positioning proposed in this invention.

[0035] Figure 2 This is a schematic diagram of the crossbeam structure of an automatic docking device for an agricultural machinery traction mechanism based on laser positioning, as proposed in this invention.

[0036] Figure 3This is an enlarged schematic diagram of layout A of an automatic docking device for agricultural machinery traction mechanism based on laser positioning proposed in this invention;

[0037] Figure 4 This is a schematic diagram of the traction end structure of an automatic docking device for agricultural machinery traction mechanism based on laser positioning proposed in this invention.

[0038] Figure 5 This is a flowchart of a calibration method for an automatic docking device for agricultural machinery traction mechanism based on laser positioning, as proposed in this invention.

[0039] In the diagram: 1. Agricultural machinery; 11. Crossbeam; 12. First electrical box; 2. Agricultural implement traction frame; 21. Second electrical box; 3. Multimodal laser positioning assembly; 31. Laser transmitter; 32. Laser receiver; 4. Magnetorheological fluid drive assembly; 41. Magnetorheological fluid universal joint; 42. Electric traction pin; 43. Force feedback detection module. Detailed Implementation

[0040] In the description of this invention, it should be noted that the terms "front," "rear," "up," "down," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the normal driving direction of the agricultural machinery (forward is the working direction) or the orientation relationship of the device after assembly. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the referred component must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0041] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "fixed," "connected," "installed," and "communication" should be interpreted broadly: "fixed" may refer to bolted connection, welding, or interference fit; "connected" may refer to rigid mechanical connection or flexible electrical signal connection; "installed" may refer to rail-mounted assembly or flange-mounted assembly; and "communication" may refer to CAN bus communication or laser networking communication. Those skilled in the art can understand the specific meaning of the above terms in this invention in conjunction with specific scenarios.

[0042] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art; in case of any inconsistency, the meaning set forth in this specification or inferred from the content of this specification shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0043] like Figures 1-4 As shown, an automatic docking device for agricultural machinery traction mechanism based on laser positioning includes agricultural machinery 1, agricultural implement traction frame 2, multimodal laser positioning component 3, dynamic attitude detection component, magnetorheological fluid drive component 4, and distributed control component.

[0044] The agricultural machinery 1 has a rear suspension system with a welded traction end crossbeam 11. The crossbeam 11 is made of low carbon steel and has undergone overall heat treatment. The upper surface of the crossbeam 11 is milled into a flat surface for attaching and fixing the laser emitter 31. A traction pin hole 13 is drilled on the top rear side of the crossbeam 11. The hole diameter is 30mm and the hole depth is 50mm. The inner wall of the hole is plated with hard chrome to reduce frictional loss when the electric traction pin 42 is inserted.

[0045] Specifically, the first electrical box 12 is fixed to the left side wall of the crossbeam 11 by four sets of internal hex bolts. The electrical box is made of ADC12 aluminum alloy die casting with a wall thickness of 4mm. The inner wall is equipped with a 35mm standard guide rail. An annular groove is opened at the edge where the box cover and the box body meet, and a nitrile rubber sealing ring with a cross section diameter of 3mm is embedded. With the help of cross countersunk bolts, an IP67 dustproof and waterproof sealing structure is formed. A GX16-4-pin waterproof aviation plug is embedded on the side of the electrical box for connecting to the external CAN bus and power line. The plug is equipped with a metal locking nut to ensure reliable connection in the field vibration environment.

[0046] The implement traction frame 2 is a U-shaped steel structure with the opening facing the tractor. The second electrical box 21 is fixed to the right side wall of the traction frame 2 by three sets of bolts. The structure of the second electrical box 21 is the same as that of the first electrical box 12, which is suitable for the compact space of the implement. A U-shaped frame is welded below the traction frame 2. Bolt holes are drilled on both sides of the frame to fix the magnetorheological fluid universal joint 41. The welding is carried out by CO2 gas shielded welding, the weld height is 6mm, and the weld is annealed at 200℃ for 1.5h after welding to eliminate the internal stress of welding.

[0047] The multimodal laser positioning component 3 includes a laser transmitter 31 and a laser receiver 32, which are aligned with each other along the docking direction between the agricultural machinery and the implement.

[0048] Specifically, the laser emitter 31 is fixed to the center of the upper surface of the traction end beam 11 by four sets of external hexagonal bolts. The bolts are symmetrically distributed along the longitudinal direction of the emitter, and a quartz glass light-transmitting cover is embedded in the center. A 1mm silicone sealing ring is placed between the light-transmitting cover and the outer shell.

[0049] The transmitter has one main laser generating module, two auxiliary laser generating modules, and one synchronous triggering module. The two auxiliary laser modules are symmetrically distributed at 30° with the main laser module as the center. The synchronous triggering module is based on the "STM32G031" MCU design and communicates with the tractor ECU through the CAN bus to receive the agricultural machinery driving speed signal and dynamically adjust the laser pulse frequency.

[0050] The laser receiver 32 is fixed to the top of the U-shaped groove of the agricultural implement traction frame 2 via a gimbal base. The gimbal base is a circular stainless steel flange, which is fixed by 3 sets of cross countersunk bolts, with the bolt heads fully embedded in the flange countersunk holes.

[0051] The receiver incorporates a 3×3 pixel Si-PIN photodiode array, an adaptive gimbal mechanism, and a MEMS tilt detection module. The array is fixed to the gimbal support platform with four sets of screws. The adaptive gimbal uses a two-phase stepper motor and a driver to achieve micro-step control. The MEMS tilt detection module communicates with the slave controller via an I2C bus to provide real-time feedback on the tilt and pitch angles of the implement, driving the gimbal to adjust the array angle and ensuring that the laser spot offset is less than 2mm.

[0052] The dynamic attitude detection component includes a traction end attitude detector and a traction end attitude detector, both of which have the same structure and are installed in the first and second electrical boxes, respectively.

[0053] The detector housing is made of ABS+PC alloy and filled with polyurethane foam shock-absorbing material to reduce the impact of agricultural machinery vibration.

[0054] Among them, the attitude detector at the traction end and the attitude detector at the traction end are equipped with MEMS gyroscopes, accelerometers and Beidou positioning modules. The antenna of the Beidou positioning module is a circular ceramic antenna.

[0055] Secondly, the data fusion module has a sampling frequency of 200Hz, uses the extended Kalman filter algorithm to process the data, and sets the EKF state vector to... Where X / Y / Z represent positions, / / For roll / pitch / roll angles, / / The angular velocity is given, and the observation vector is derived from laser positioning and BeiDou data. The process noise covariance matrix is ​​also given. Observation noise covariance matrix After fusion, the data error position is ≤0.5mm and the angle is ≤0.1°, and it is transmitted to the control component via CAN bus.

[0056] The magnetorheological fluid drive assembly 4 is fixed to the U-shaped frame below the implement traction frame 2, and includes a magnetorheological fluid universal joint 41, an electric traction pin 42 and a force feedback detection module 43.

[0057] Specifically, the magnetorheological fluid universal joint 41 housing is a steel spherical shell, which is fixed to the U-shaped frame by bolts; the housing is filled with magnetorheological fluid and has an internal excitation coil assembly. The coil is connected to the controller through a 1.5mm² high-temperature resistant silicone rubber wire, and the cable is run through a Φ10mm metal corrugated pipe.

[0058] The magnetorheological fluid universal joint is a ball-joint integrated structure, consisting of four units: a mechanical steering module, a magnetorheological force control module, a sealing and protection module, and a sensing feedback module.

[0059] The assembly relationship of each module is as follows: the mechanical steering module serves as the load-bearing base, the magnetorheological force control module is embedded in its internal cavity, the sealing and protection module is arranged circumferentially along the movement gap, and the sensing feedback module is integrated at the center of the force-bearing end.

[0060] The mechanical steering module is used to achieve ±10° angle compensation and includes the ball bearing housing and ball head assembly.

[0061] The ball bearing shell has a bowl-shaped cavity structure, and the ball head assembly is a hemisphere and a cylindrical shaft integrated into one piece. The center of the hemisphere and the axis of the cylindrical shaft are collinear to ensure uniform force distribution during turning.

[0062] The magnetorheological force control module is responsible for achieving 0-5kN thrust and rapid response, and includes a dual-cavity working chamber, excitation coil assembly and floating compensation mechanism.

[0063] The dual-chamber working chamber has two annular working chambers, one above the other, circumferentially opened along the inner wall of the spherical tile. The cross-section of the chamber is rectangular. The two chambers are symmetrically distributed with the center of the sphere as the point of distribution. The pressure is balanced by a φ3mm connecting hole in the middle. The chambers are filled with magnetorheological fluid and sealed with M10 stainless steel plugs after the fluid is injected.

[0064] The coil slots of the excitation coil assembly are located on the outer side of the working cavity on the inner wall of the ball bearing, and are four annular coil slots distributed circumferentially. The winding adopts a dual-winding redundancy design, with 200 turns in each group. The two groups of windings are connected in series, and the lead wires pass through the φ5mm waterproof hole at the bottom of the ball bearing.

[0065] In terms of magnetic circuit design, the spherical shell is used as the magnetic conductive substrate. The magnetic field generated by the coil passes through the working cavity vertically to ensure that the magnetorheological fluid is fully magnetized. The floating compensation mechanism has a φ15mm floating piston embedded at the bottom of the lower cavity. The piston and the cavity wall are sealed with a gap. Above the piston is the magnetorheological fluid cavity, and below it is the nitrogen cavity, which is used to compensate for the thermal expansion and contraction of the magnetorheological fluid and avoid leakage caused by a sudden increase in the cavity pressure.

[0066] The sealing and protection module is adapted to dusty and humid working conditions in the field. It adopts a three-level composite sealing structure and is arranged along the movement gap between the ball head and the ball bearing.

[0067] The first-level dustproof system uses a lip-shaped dustproof ring to prevent field dust and straw debris from entering.

[0068] The secondary main seal is a V-type combination seal ring.

[0069] The third-level isolation is to open an annular oil cavity between the dust seal and the main seal, fill it with agricultural machinery-specific lithium-based grease, form a lubrication isolation zone, and reduce the wear of the seals;

[0070] A φ1mm oil drain hole is opened at the bottom of the oil chamber to prevent excessive oil pressure from damaging the seal.

[0071] The sensor feedback module is used to implement closed-loop control and includes force sensors and angle sensors.

[0072] The force sensor is a strain gauge thrust sensor, which is attached to the center of the bottom of the ball head hemisphere; the angle sensor is a non-contact Hall angle sensor, which is fixed to the bottom of the ball bearing and is used to collect the universal joint deflection angle in real time to provide feedback signals for attitude correction.

[0073] The lower 20mm section of the electric traction pin 42 is a rectangular spline that mates with the spline hole of the universal joint output shaft, with a set screw at the mating point; the upper 40mm section is a tapered structure for insertion into the traction pin hole 13; an annular groove is provided in the middle section of the traction pin for installing the force feedback detection module; the traction pin drive motor is a 24V DC geared motor, and extension and retraction are achieved through a T-shaped lead screw.

[0074] The force feedback detection module 43 is a strain gauge sensor with a ring structure, nested in the annular groove of the traction pin and fixed by a set screw; the sensor signal line and the universal joint coil line pass through a metal bellows and are connected to the analog interface of the controller.

[0075] The distributed control component includes a master controller and slave controllers, which communicate bidirectionally with the CAN bus via a laser network link;

[0076] Specifically, the main controller is installed on a 35mm guide rail inside the first electrical box 12, integrating two CANFD interfaces and one Ethernet interface; the main controller's CAN interface is connected to the tractor ECU, the laser emitter 31 synchronous trigger module, and the traction end attitude detector respectively through twisted shielded cables, with the shielding layer grounded at one end;

[0077] The controller is installed on a rail of the same specification inside the second electrical box 21, integrating 1 CAN interface and 2 PWM output interfaces; the controller's PWM interface is connected to the laser receiver 32 gimbal motor, the magnetorheological fluid universal joint 41 coil, and the electric traction pin 42 motor respectively through 1.0mm² wires.

[0078] Laser networking link: The link adopts time-division multiple access communication mode with a period of 25ms, a communication rate of 10Mbps, and supports automatic reconnection.

[0079] like Figure 5 As shown, the automatic docking calibration method of the above-mentioned device includes the following steps:

[0080] S1. Initialization and Network Setup:

[0081] After the agricultural machinery starts, the main controller is powered on and broadcasts a synchronization signal through the laser network link; after receiving the signal from the controller, each implement performs a self-test on the laser receiver 32, the magnetorheological fluid drive assembly 4, and the attitude detector at the traction end.

[0082] Laser receiver self-test: Light up the test laser and check if the array has ≥8 pixels receiving signals;

[0083] Drive component self-test: Control the universal joint coil to pass 1A current and check if there is angle feedback; Control the traction pin to extend or retract 5mm and check if the motor operates;

[0084] Attitude detector self-test: checks the number of BeiDou satellites searched and whether the gyroscope / accelerometer has data output;

[0085] The self-test results are fed back to the main controller via the CAN bus. The main controller filters valid slave nodes, assigns IDs (e.g., ID1 = seeder, ID2 = fertilizer applicator), and determines the docking order according to the distance from the agricultural machinery, from closest to furthest, to establish a distributed laser communication network.

[0086] S2. Multimodal laser coarse positioning:

[0087] The main controller sends a main laser start command to the laser emitter 31, and the 650nm main laser is emitted.

[0088] The 3×3 pixel array of the laser receiver 32 captures the light spot, and the initial relative position is calculated based on the pixel light intensity distribution using Formula 1. :

[0089]

[0090]

[0091] in, Let i be the light intensity value of the i-th pixel. and Let be the coordinates of the i-th pixel;

[0092] The MEMS tilt detection module collects the tilt angle α and pitch angle β of the implement, and sends adjustment commands to the gimbal drive motor. The motor adjusts the angle once every 10ms until the center of the light spot is reached. The offset from the center of the array is less than 2mm;

[0093] If the agricultural machinery reverses at a speed greater than 3 m / s, the main controller sends a speed reduction command to the tractor ECU, reducing the speed to 1 m / s, and continues after the light spot stabilizes.

[0094] S3. Dynamic Attitude Fusion Precision Positioning

[0095] The main controller sends an auxiliary laser start command to the laser emitter 31, and the two sets of 850nm near-infrared auxiliary lasers emit power of 10mW.

[0096] The laser receiver 32 synchronously receives the main and auxiliary laser signals, combines them with the EKF fusion data from the attitude detector at the towed end, and transmits the X / Y / Z position and α / β / γ angle to the main controller via the CAN bus.

[0097] The main controller, based on the EKF algorithm, fuses laser positioning and attitude data to output precise deviation. With an accuracy of ≤±3mm, the EKF state update formula is as follows:

[0098]

[0099] in Let k be the filtered state. Predict the state at time k-1. For Kalman gain, Let k be the observation value at time k. The observation matrix;

[0100] If a single auxiliary laser is blocked, it automatically switches to redundant positioning of "main laser + single auxiliary laser + BeiDou data", increasing the weight of BeiDou data to 0.5 and maintaining an accuracy of ≤±3mm; if both auxiliary lasers are blocked, it switches to dual redundancy of "main laser + attitude data", with an accuracy of ≤±5mm.

[0101] S4. Magnetorheological fluid-driven dynamic correction:

[0102] The main controller sends a correction command to the slave controller based on the precision positioning deviation;

[0103] Side slip angle At this time, the controller outputs a transverse excitation current of 0.5-2A. The horizontal angle of the universal joint is adjusted, with the current finely adjusted by 0.1A every 0.05s until... ;

[0104] Pitch angle or roll angle At this time, output longitudinal excitation current of 0.5-2A, adjust the vertical angle of the universal joint until... ;

[0105] The force feedback detection module 43 monitors the contact force F between the traction pin and the traction pin hole 13 in real time. If F > 1kN, the excitation current is reduced from the controller, and the thrust is reduced from 5kN to 2kN. At the same time, the universal joint angle is finely adjusted.

[0106] If there is no signal from the force feedback module, it will automatically switch to "time control mode" and control the locking to be triggered after the traction pin is inserted 60mm.

[0107] S5. Locking and Coordination Correction:

[0108] The electric traction pin 42 is inserted into the traction pin hole 13 to a depth of >90%, and the F value detected by the force feedback module is stable for 1 second.

[0109] The controller sends a "docking complete" signal to the main controller, and the main controller controls the traction pin locking mechanism to operate.

[0110] The main controller sends a synchronization correction signal to the slave controllers of the subsequent implements to be docked. The subsequent slave controllers pre-compensate for deviations based on the attitude data of the preceding implements, and achieve parallel docking.

[0111] When multiple agricultural machines work together, the synchronization control error of the main controller to each slave node is <1ms, the docking time of a single slave node is <5s, and the total docking time of 3 slave nodes is <10s.

[0112] S6. Post-docking dynamic monitoring:

[0113] After docking is completed, the laser transmitter 31 switches to 1mW low-power operation, and the laser receiver 32 continuously monitors the relative attitude deviation.

[0114] If the deviation is greater than 2mm, the main controller triggers a secondary correction, and the slave controller controls the universal joint for fine adjustment.

[0115] The force feedback module collects the locking force F every 500ms. If F < 0.3kN, the controller triggers an alarm and controls the traction pin to re-lock.

[0116] All data is uploaded to the agricultural machinery management platform via a 4G module and stored in an SQL Server database.

[0117] This device achieves automatic docking through the coordinated use of positioning, attitude, drive, and control. First, the main and auxiliary lasers of the multimodal laser positioning component 3, combined with an adaptive gimbal, achieve coarse positioning of agricultural machinery and implements. Second, the dynamic attitude detection component, through the EKF algorithm, integrates data from gyroscopes, accelerometers, and BeiDou to output precise attitude deviations. Then, the magnetorheological fluid drive component 4 responds to control commands and achieves dynamic correction through the adjustment of the magnetorheological fluid universal joint angle and the extension and retraction of the traction pin. Finally, the distributed control component, through laser networking, enables parallel docking and real-time monitoring of multiple agricultural machines.

[0118] Specifically, laser positioning provides an initial position reference, attitude detection compensates for field vibrations and terrain deviations, magnetorheological fluid drive enables rapid response, and distributed control ensures synchronization of multiple nodes. These four technologies work together to solve the problems of low accuracy, slow efficiency, and reliance on manual labor in traditional docking, making it suitable for complex working conditions such as wheat straw returning to the field and corn residual film fields.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An automatic docking device for agricultural machinery traction mechanisms based on laser positioning, characterized in that, This includes agricultural machinery, implement traction frames, multimodal laser positioning components, dynamic attitude detection components, magnetorheological fluid drive components, and distributed control components; The agricultural machinery is fixed with a traction end crossbeam (11) at the rear. A traction pin hole (13) is opened at the top of the rear side of the traction end crossbeam (11). A first electrical box (12) is installed on the side wall of the crossbeam (11). A second electrical box (21) is installed on the side wall of the agricultural implement traction frame. The multimodal laser positioning component includes a laser emitter (31) and a laser receiver (32). The laser emitter (31) is fixed to the top of the traction end beam (11), and the laser receiver (32) is fixed to the inside of the implement traction frame. The two are directly opposite each other along the docking direction of the agricultural machinery and the implement traction frame. The laser emitter (31) has a built-in main laser generating module, two auxiliary laser generating modules and a synchronous triggering module. The main laser generating module emits visible light laser, and the two auxiliary laser generating modules emit near-infrared polarized laser and are symmetrically distributed at 30° with the main laser generating module as the center. The synchronous triggering module is electrically connected to the agricultural machinery ECU through the CAN bus. The laser receiver (32) has a built-in 3×3 pixel Si-PIN photodiode array, an adaptive gimbal mechanism and a MEMS tilt angle detection module. The adaptive gimbal carries the photodiode array, and the MEMS tilt angle detection module is electrically connected to the gimbal drive motor. The dynamic attitude detection component includes a traction end attitude detector and a traction end attitude detector. The traction end attitude detector is fixed in the first electrical box (12), and the traction end attitude detector is fixed in the second electrical box (21) and close to the laser receiver (32). Both the traction end attitude detector and the traction end attitude detector integrate a MEMS gyroscope, a three-axis accelerometer, a Beidou positioning module and a data fusion module. The output ends of the MEMS gyroscope, accelerometer and Beidou module are electrically connected to the input end of the data fusion module. After the data fusion module processes the data through the extended Kalman filter algorithm, it is electrically connected to the distributed control component. The magnetorheological fluid drive assembly is fixed directly below the implement traction frame and includes a magnetorheological fluid universal joint (41), an electric traction pin (42), and a force feedback detection module (43). The magnetorheological fluid universal joint (41) is fixed below the implement traction frame by a U-shaped frame and has an internal excitation coil assembly and magnetorheological fluid. The excitation coil assembly is electrically connected to the distributed control assembly. One end of the electric traction pin (42) is connected to the output shaft of the universal joint via a spline, and the other end is a tapered structure for insertion into the traction pin hole (13). The force feedback detection module (43) is fitted on the side wall of the electric traction pin (42) and is electrically connected to the distributed control assembly. The distributed control component includes a master controller and a slave controller. The master controller is fixed in the first electrical box (12), and its signal input end is electrically connected to the agricultural machinery ECU, the synchronous trigger module of the laser transmitter (31), and the traction end attitude detector via the CAN bus. Its signal output end communicates with the slave controller via the laser networking link. The slave controller is fixed in the second electrical box (21), and its signal input end is electrically connected to the laser receiver (32) gimbal motor, the traction end attitude detector, and the force feedback detection module (43) via the CAN bus. Its signal output end is electrically connected to the magnetorheological fluid universal joint (41) and the electric traction pin (42) via the wire. The master controller supports communication with at least 3 slave controllers at the same time, realizing the collaborative docking of 1 agricultural machine with multiple agricultural implements.

2. The automatic docking device for agricultural machinery traction mechanism based on laser positioning according to claim 1, characterized in that, In the multimodal laser positioning component, the main laser generating module of the laser emitter (31) outputs visible light laser with a wavelength of 650nm, and the two auxiliary laser generating modules output near-infrared polarized laser with a wavelength of 850nm. The polarization directions are orthogonally distributed. The 3×3 pixel Si-PIN photodiode array of the laser receiver (32) has a single pixel size of 1mm×1mm and a response wavelength covering 600-900nm. The adaptive gimbal mechanism is driven by a two-phase 42 stepper motor with an adjustable step angle of 0.9° / 1.8°. The measurement range of the MEMS tilt detection module is ±45°.

3. The automatic docking device for agricultural machinery traction mechanism based on laser positioning according to claim 1, characterized in that, In the dynamic attitude detection component, the MEMS gyroscope range of the traction end attitude detector and the traction end attitude detector is ±2000° / s, the zero bias stability is ≤5° / h, the three-axis accelerometer range is ±16g, the Beidou positioning module supports dual-frequency positioning, the sampling frequency of the data fusion module is 200Hz, and the state update frequency of the extended Kalman filter algorithm is consistent with the sampling frequency.

4. The automatic docking device for agricultural machinery traction mechanism based on laser positioning according to claim 1, characterized in that, In the magnetorheological fluid drive assembly, the magnetorheological fluid built into the magnetorheological fluid universal joint (41) has a viscosity of ≤0.1 Pa·s under zero magnetic field. The excitation coil assembly is a double winding structure wound with enameled copper wire, with 200 turns per winding. The electric traction pin (42) has a tapered structure with a taper of 1:10 and an effective insertion length of 50-80 mm. The force feedback detection module (43) adopts a strain gauge force sensor with a measurement range of 0-5 kN.

5. An automatic docking device for agricultural machinery traction mechanism based on laser positioning according to claim 1, characterized in that, In the distributed control component, the laser networking link adopts time-division multiple access communication mode with a communication rate of 10Mbps and supports an automatic reconnection mechanism.

6. The automatic docking device for agricultural machinery traction mechanism based on laser positioning according to claim 1, characterized in that, Both the first electrical box (12) and the second electrical box (21) are made of aluminum alloy die casting. The U-shaped frame connecting the agricultural implement traction frame and the magnetorheological fluid drive assembly is fixed by seam welding.

7. A calibration method for an automatic docking device for an agricultural machinery traction mechanism based on laser positioning as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Initialization and networking: After the agricultural machinery is started, the main controller is powered on and broadcasts a synchronization signal through the laser networking link. After each implement receives the signal from the controller, it performs self-tests on the laser receiver (32), magnetorheological fluid drive component, and attitude detector at the traction end. The results are fed back to the main controller through the CAN bus. The main controller assigns slave node IDs, determines the docking order of multiple implements, and establishes a distributed laser communication network. S2. Multimodal laser coarse positioning: The main controller sends the main laser start command to the laser transmitter (31). After the visible light main laser is emitted, the photodiode array of the laser receiver (32) captures the light spot and calculates the initial relative position. The MEMS tilt detection module collects the side tilt and pitch angle of the agricultural implement and drives the adaptive gimbal to adjust so that the light spot offset is <2mm. S3, Dynamic attitude fusion fine positioning, the main controller starts two near-infrared auxiliary lasers, the laser receiver (32) synchronously receives the main and auxiliary laser signals, the dynamic attitude detection component transmits the attitude data to the main controller, the main controller fuses the laser positioning and attitude data through the extended Kalman filter algorithm, and outputs the X / Y / Z axis and three-dimensional angle deviation. If a single auxiliary laser is blocked, it automatically switches to the redundant positioning of the main laser, single auxiliary laser and attitude data. S4, magnetorheological fluid driven dynamic correction, the main controller sends instructions to the slave controller according to the deviation, the slave controller outputs excitation current, when the side slip angle is >1mm, the lateral current is adjusted, when the pitch and roll angles are >0.5°, the longitudinal current is adjusted, the force feedback detection module (43) monitors the contact force, when the force value is >1kN, the thrust is reduced and the universal joint angle is finely adjusted; S5. Locking and Coordination Correction: After the electric traction pin (42) is inserted into the traction pin hole (13) to a depth of >90% and the force value is stable for 1s, the controller sends a docking completion signal. The main controller sends a synchronization correction signal to the subsequent slave controller. The subsequent agricultural implements pre-compensate for deviations based on the previous posture data to achieve parallel docking. S6. Dynamic monitoring after docking: After docking is completed, the laser transmitter (31) switches to low power operation and the laser receiver (32) continuously monitors the relative attitude deviation. When the deviation is greater than 2mm, the main controller triggers secondary correction and the slave controller controls the universal joint to make fine adjustments.

8. The calibration method for an automatic docking device of an agricultural machinery traction mechanism based on laser positioning according to claim 7, characterized in that, In step S2, the main laser positioning distance covers the initial docking distance between the agricultural machinery and implements of 0.5-3m. The adaptive gimbal adjustment response time and the feedback frequency of the MEMS tilt detection module are consistent, both being 100Hz. During the adjustment process, the center of the light spot is always kept in the 3×3 pixel area of ​​the center of the photodiode array to avoid positioning interruption.

9. The calibration method for an automatic docking device of an agricultural machinery traction mechanism based on laser positioning according to claim 7, characterized in that, In step S3, under the redundant positioning mode, the main controller maintains a positioning accuracy of ≤3mm by increasing the weight of the centimeter-level precision data from the BeiDou positioning module. If both sets of auxiliary lasers are blocked, the weight of the fusion of the main laser and attitude data is strengthened to trigger dual redundant positioning with an accuracy of ≤5mm, ensuring continuous docking.

10. The calibration method for an automatic docking device of an agricultural machinery traction mechanism based on laser positioning according to claim 7, characterized in that, In step S5, during the multi-farm machinery collaborative correction, the main controller's synchronous control error for each slave node is <1ms, the docking time of a single slave node is <5s, and the total docking time of the three slave nodes is <10s. After docking, the locking torque of the electric traction pin (42) is 20-30N·m, and the force feedback detection module (43) continuously monitors the locking force. When the force value is <0.3kN, an alarm is triggered and the locking is re-locked.

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