A plant protection machine wide spraying rod posture adjusting system and a posture control method thereof

Abstract

The present application relates to a kind of plant protection machine wide spraying boom posture adjusting system and its posture control method, the system includes height adjusting component, horizontal adjusting component, side spraying boom component and hydraulic control system, horizontal adjusting component includes middle spraying boom support, leveling oil cylinder, middle spraying boom, spraying boom posture controller and inclination sensor, the upper portion of middle spraying boom support is hinged with the middle portion of crossbeam, the lower portion is hinged with one end of leveling oil cylinder, the other end of leveling oil cylinder is hinged with the end of crossbeam, middle spraying boom is fixed on middle spraying boom support by pipe clamp, spraying boom posture controller and inclination sensor are respectively arranged in middle spraying boom support or middle spraying boom, and spraying boom posture controller receives the detection information of inclination sensor, and controls hydraulic control system to drive leveling oil cylinder to extend or retract;The horizontal adjusting component of the present application is driven by leveling oil cylinder to carry out angle adjustment to spraying boom support;Face to the ups and downs of field conditions, spraying boom can be adjusted to left and right within a certain angle range, and relative ground level is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of agricultural machinery, and in particular relates to a wide-width spray boom attitude adjustment system for a plant protection machine and its attitude control method. Background Technology

[0002] Agricultural production, as the cornerstone of social development and progress, has always played a crucial role. Crop protection is a vital component of agricultural production. To meet the stringent technical requirements of modern plant protection, such as large-scale and precision applications, large-scale plant protection machinery has become increasingly widely used. However, during the use of plant protection machines, the complex and varied field conditions, including uneven ground, and the large swing amplitude of the spray boom on wide-bar sprayers during pesticide application, affect spray uniformity, reduce application quality, and lead to over-spraying and under-spraying, significantly impacting the environment and food safety. Excessive boom vibration can even cause collisions with the ground, damaging the machine. To effectively mitigate these impacts, higher performance requirements are placed on the boom suspension of large-bar plant protection machines. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the first objective of this invention is to provide a wide-width spray boom attitude adjustment system for plant protection machines, which can adjust the angle of the spray boom to ensure that it is level with the ground. The second objective of this invention is to provide a wide-width spray boom attitude control method for plant protection machines.

[0004] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0005] A wide-width spray boom attitude adjustment system for an agricultural plant protection machine includes a height adjustment component, a level adjustment component, a side spray boom component, and a hydraulic control system. The height adjustment component includes a lifting cylinder and two parallel four-bar linkages fixed in the middle by a crossbar. One end of each parallel four-bar linkage is fixed to a crossbeam, and both ends of the lifting cylinder are hinged to the crossbeam and the crossbar, respectively. The level adjustment component includes a central spray boom support, a leveling cylinder, a central spray boom, a spray boom attitude controller, and a tilt sensor. The upper part of the central spray boom support is hinged to the middle of the crossbeam, and the lower part is hinged to one end of the leveling cylinder. The other end of the leveling cylinder... The middle spray bar is hinged to the end of the crossbeam. It is fixed to the middle spray bar support by a pipe clamp. Multiple nozzles A are evenly spaced on the middle spray bar. The spray bar attitude controller and tilt sensor are respectively installed on the middle spray bar support and the middle spray bar. The spray bar attitude controller receives the detection information from the tilt sensor and controls the hydraulic control system to drive the leveling cylinder to extend and retract, thereby adjusting the tilt angle of the middle spray bar relative to the reference surface. The two ends of the middle spray bar support are hinged to two side spray bar assemblies, and the extension and retraction of the two side spray bar assemblies are controlled by the left extension cylinder and the right extension cylinder, respectively.

[0006] As a preferred embodiment: the spray boom attitude controller includes a microcontroller, and an A / D conversion circuit, a clock circuit, a reset circuit, a potentiometer, a relay, and a power supply module connected to the microcontroller. The power supply module converts 12V voltage to 5V voltage to power the microcontroller, potentiometer, and relay. The A / D conversion circuit converts various analog signals into digital signals to provide to the microcontroller. The potentiometer provides preset angle information to the microcontroller. The relay receives control signals from the microcontroller, thereby controlling the hydraulic control system.

[0007] As a preferred embodiment: the hydraulic control system includes an oil tank, a filter, a hydraulic pump, a pressure gauge, a two-position three-way solenoid directional valve (65), and a solenoid relief valve (66) connected in sequence. The two-position three-way solenoid directional valve is connected to the leveling cylinder, the lifting cylinder, the left-side deployment cylinder, and the right-side deployment cylinder respectively through multiple three-position four-way solenoid directional valves. The spray bar attitude controller controls the state of the two-position three-way solenoid directional valve and the multiple three-position four-way solenoid directional valves to enable the leveling cylinder, the lifting cylinder, the left-side deployment cylinder, and the right-side deployment cylinder to complete the corresponding actions.

[0008] As a preferred embodiment: the parallel four-bar linkage includes lifting rods and vertical fixing sleeves. The lifting rods are I-shaped, with two lifting rods stacked on top of each other at intervals, and each end of the two lifting rods is hinged to both ends of a vertical fixing sleeve.

[0009] As a preferred embodiment: the side spray bar assembly includes an inner tube and an outer tube that are nested together. Both the inner tube and the outer tube are provided with nozzles B at intervals. One end of the outer tube is fixed with a first connector. Both ends of the middle spray bar bracket are provided with sleeves. The first connector is provided with a shaft, which is inserted into the sleeve. The upper part of the first connector is also provided with a protrusion, which is hinged to the corresponding left or right expansion cylinder.

[0010] As a preferred embodiment: the outer end of the side spray bar assembly is further provided with an end spray bar assembly, the end spray bar assembly including an end spray bar, a second connector and a nozzle C, a plurality of nozzles C are fixed at intervals on the end spray bar, one end of the second connector is fixed to the side spray bar assembly and the other end is fixed to the end spray bar.

[0011] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0012] A method for controlling the attitude of a wide-width spray boom of a plant protection machine, employing any one of the above-mentioned wide-width spray boom attitude adjustment systems, and the control process is as follows:

[0013] After the equipment is started, the tilt sensor collects the tilt angle information of the middle spray boom in real time during operation. The spray boom attitude controller subtracts the acquired tilt angle information from the set expected angle to obtain the difference. If the difference is less than the set threshold, the middle spray boom does not need to be adjusted. If the difference is greater than the threshold, the spray boom attitude controller adjusts the on / off state of the corresponding solenoid valve of the hydraulic control system according to the difference information, changes the direction of the oil circuit and the hydraulic oil flow, and thus changes the extension and retraction of the leveling cylinder, so that the middle spray boom is automatically leveled. The above steps are repeated continuously during the adjustment process until the difference is less than the set threshold, and the adjustment process ends.

[0014] As a preferred embodiment, the boom attitude controller employs a PID algorithm for closed-loop control of the extension of the leveling cylinder. The specific PID control process is as follows: The tilt sensor collects actual tilt angle information, calculates the error value between the preset tilt angle and the actual tilt angle, multiplies the error value by a proportional coefficient to obtain the output value of the proportional control section, accumulates the calculated error values, and multiplies them by the integral time to obtain the output value of the integral control section; the rate of change of the error value is multiplied by the derivative time to obtain the output value of the derivative control section; the output values ​​of the proportional control section, integral control section, and derivative control section are added together to obtain the final control output signal. The boom attitude controller sends a level signal to the relay based on the final control output signal to control the on / off time and valve core direction of the corresponding solenoid valve in the hydraulic control system; after determining the PID... During the parameter setting process, the integral and derivative times are first set to zero, and only the proportional coefficient is adjusted. By observing the steady-state error value, overshoot, and response speed indicators of the system output, the proportional coefficient is gradually increased or decreased to find a suitable range for automatic leveling of the nozzle. Then, integral and derivative control are gradually introduced, and the integral and derivative coefficients are adjusted to further improve the system's response characteristics. If φd and φa are the preset tilt angle and the actual tilt angle, respectively, and the tilt angle errors e(i) and Ui are respectively...

[0015]

[0016]

[0017]

[0018]

[0019] In the formula, KP is the proportional coefficient; KI is the integral coefficient; KD is the derivative coefficient; T1 is the integral time constant; and TD is the derivative time constant. After adjustment, the final PID parameters are determined to be KP=5, KI=0.03, and KD=1.

[0020] As a preferred solution: A Cartesian coordinate system is established with the hinge point between the central spray boom bracket and the crossbeam as the center point O, the z-axis perpendicular to the chassis plane, the y-axis along the axis of the central spray boom bracket, and the forward direction of the sprayer as the x-axis. Point O is the hinge point between the central spray boom bracket and the crossbeam, and points A and B are the hinge points between the leveling cylinder and the crossbeam, and between the leveling cylinder and the central spray boom bracket, respectively. The tilt angle β of the central spray boom bracket is the rotation angle of the central spray boom bracket around the x-axis. The relationship between the tilt angle β and the extension / retraction of the leveling cylinder is calculated as follows:

[0021] When the middle spray boom support is in a horizontal position relative to the sprayer, the angle between the middle spray boom support and the crossbeam is:

[0022]

[0023] With the crossbeam as the reference, when the middle spray boom support is at its rightward tilt limit, the maximum rightward tilt angle of the middle spray boom support relative to the sprayer is:

[0024]

[0025] With the crossbeam as the reference, when the middle spray boom support is at its leftward tilt limit, the maximum leftward tilt angle of the middle spray boom support relative to the sprayer is:

[0026]

[0027] The adjustable range of the central spray boom bracket is:

[0028]

[0029] In the formula, This represents the maximum rightward tilt angle of the central spray boom support; This represents the maximum leftward tilt angle of the central spray boom support; θ The angle between the line connecting hinge point AO and hinge point OB; l a The length of the line connecting the hinge point AO is in mm. l b The length of the line connecting the hinge point OB is in mm. l The initial length of the leveling cylinder when the middle spray boom support is horizontal, in mm; l 1. l 2 represents the extension and retraction of the leveling cylinder at the right and left extreme positions, respectively, in mm.

[0030] As a preferred embodiment, the preset angle set for the central boom support during operation is φd, and the roll angle of the sprayer during operation is φ. The difference between the preset angle φd and the roll angle φ maintained at the previous moment is equal to the sum of the tilt angle β of the boom support relative to the sprayer at the previous moment and the adjustment amount Δβ of the boom support relative to the target. Therefore, the adjustment amount Δβ of the tilt angle of the boom support relative to the sprayer at this time is:

[0031]

[0032] The angle value that should be controlled at the current moment is:

[0033]

[0034] In automatic leveling mode, the boom support adjusts according to its angle relative to the sprayer body. When the sprayer body tilts to the left, the piston of the leveling cylinder retracts, causing the boom support to adjust to the right to maintain a relatively horizontal state. The corresponding response time is determined by calculating the piston retraction stroke, as shown in the following formula:

[0035]

[0036] When the sprayer body tilts to the right, the piston of the leveling cylinder extends, causing the spray boom bracket to adjust to the left to maintain a relatively horizontal state. The response time is calculated based on the piston extension stroke:

[0037]

[0038] In the formula, D is the cylinder diameter of the leveling cylinder, in mm; d The rod diameter for leveling the hydraulic cylinder is measured in mm. The piston extension / retraction amount of the hydraulic cylinder is used for leveling, and the unit is mm; q The flow rate of the hydraulic cylinder is adjusted to be measured in L / min.

[0039] When the automatic leveling adjustment of the spray boom bracket is tilted to the right or left, each 1° rotation is considered to be a consistent extension and retraction of the leveling cylinder. Therefore, the response time for each 1° rotation of the spray boom bracket is:

[0040] .

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] This invention designs a three-section boom support, a height adjustment component, and a leveling component based on the boom posture adjustment control principle. The three-section boom support allows the left and right sections of the boom to fold, reducing the lateral space occupied and ensuring maneuverability. The lifting mechanism adopts a double parallel four-bar linkage, driven by a lifting cylinder for upward and downward adjustment. This allows the sprayer boom mechanism to meet the spraying needs of crops at different stages. The leveling component uses a leveling cylinder to drive the boom support for angle adjustment. When facing undulating field conditions, the boom can be tilted left and right within a certain angle range to ensure relative level with the ground. Attached Figure Description

[0043] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0044] Figure 1 This is a schematic diagram of the overall structure of the nozzle attitude adjustment system of the present invention;

[0045] Figure 2 This is a structural schematic diagram of the height adjustment component and the horizontal adjustment component of the present invention at one angle;

[0046] Figure 3 This is a schematic diagram of the height adjustment component and the horizontal adjustment component of the present invention from another angle;

[0047] Figure 4 This is a schematic diagram of the operation of the height adjustment component of the present invention;

[0048] Figure 5 This is a schematic diagram of the side spray bar assembly and the end spray bar assembly of the present invention;

[0049] Figure 6 This is a schematic diagram of the end structure of the side spray bar assembly of the present invention;

[0050] Figure 7 This is a schematic diagram of the connection structure between the end of the side spray bar assembly and the end of the middle spray bar bracket of the present invention;

[0051] Figure 8 This is a structural schematic diagram of the end spray bar assembly of the present invention at one angle;

[0052] Figure 9 This is a structural schematic diagram of the end spray bar assembly of the present invention from another angle;

[0053] Figure 10 This is a block diagram of the control system principle of the present invention;

[0054] Figure 11 This is a connection diagram of the microcontroller, potentiometer, tilt sensor, relay and other components of the present invention;

[0055] Figure 12 This is a schematic diagram of the hydraulic control system of the present invention;

[0056] Figure 13 This is a schematic diagram of the control method of the present invention;

[0057] Figure 14 This is a schematic diagram of the automatic leveling system for the middle spray bar bracket of the present invention.

[0058] Figure 15 This is a schematic diagram of the PID system control principle of the present invention;

[0059] Figure 16 The curves showing the changes in the tilt sensor before and after filtering according to the present invention are shown.

[0060] Figure 17 This is a schematic diagram showing three states of the middle spray bar bracket during leveling in this invention.

[0061] Figure 18 This is a schematic diagram of the site test for the present invention.

[0062] Figure 19 This is a schematic diagram of the field test results of the present invention;

[0063] Figure 20 This is a schematic diagram of the field test route planning of the present invention;

[0064] Figure 21 This is a schematic diagram of the field test results of the present invention. Detailed Implementation

[0065] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0066] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0067] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0068] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0069] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0070] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0071] like Figures 1 to 9As shown, a wide-width spray boom attitude adjustment system for an agricultural plant protection machine includes a height adjustment component 1, a horizontal adjustment component 2, a side spray boom component 3, and a hydraulic control system. The height adjustment component 1 includes a lifting cylinder 13 and two parallel four-bar linkages fixed in the middle by a crossbar. One end of each parallel four-bar linkage is fixed to a crossbeam 14. The two ends of the lifting cylinder 13 are hinged to the crossbeam 14 and the crossbar, respectively. The horizontal adjustment component includes a central spray boom support 21, a leveling cylinder 22, a central spray boom 23, a spray boom attitude controller 26, and a tilt sensor. The upper part of the central spray boom support 21 is hinged to the middle of the crossbeam 14, and the lower part is hinged to one end of the leveling cylinder 22. The other end of the leveling cylinder 22... Hinged to the end of the crossbeam 14, the central spray bar 23 is fixed to the central spray bar bracket 21 by a pipe clamp 24, and multiple nozzles A25 are evenly spaced on the central spray bar 23. The spray bar attitude controller 26 and the tilt sensor are respectively installed on the central spray bar bracket 21 and the central spray bar 23. The spray bar attitude controller 26 receives the detection information from the tilt sensor and controls the hydraulic control system to drive the leveling cylinder 22 to extend and retract, thereby adjusting the tilt angle of the central spray bar 23 relative to the reference surface. The two ends of the central spray bar bracket 21 are respectively hinged to two side spray bar assemblies 3, and the extension and retraction of the two side spray bar assemblies 3 are controlled by the left extension cylinder 27 and the right extension cylinder 28, respectively.

[0072] The parallel four-bar linkage includes lifting rods 11 and vertical fixing sleeves 12. The lifting rods 11 are I-shaped, with two lifting rods 11 stacked on top of each other at intervals, and each end of the two lifting rods 11 is hinged to both ends of a vertical fixing sleeve 12.

[0073] The side spray bar assembly 3 includes an inner tube 31 and an outer tube 32 nested together. Both the inner tube 31 and the outer tube 32 are spaced apart by nozzles B36. A first connector 33 is fixed to one end of the outer tube 32. Sleeves are provided at both ends of the central spray bar bracket 21. A shaft 34 is provided on the first connector 33 and inserted into the sleeve. A protrusion 37 is also provided on the upper part of the first connector, and the protrusion 37 is hinged to the corresponding left-side or right-side deployment cylinder 27 or 28. A support plate 35 is also fixed to the end of the outer tube 32 near the left-side or right-side deployment cylinder 27 or 28.

[0074] The outer end of the side spray bar assembly 3 is also provided with an end spray bar assembly 4. The end spray bar assembly 4 includes an end spray bar 41, a second connector 42 and a nozzle C43. Multiple nozzles C43 are fixed at intervals on the end spray bar 41. One end of the second connector 42 is fixed to the side spray bar assembly 3 and the other end is fixed to the end spray bar 41.

[0075] The second connector 42 is also provided with an arc-shaped adjustment groove 421. One end of the end spray bar 41 is fixed with an end plate 412 through a sleeve 411. The end plate 412 is fixed with the second connector 42 and can adjust the tilt angle along the arc-shaped adjustment groove 421. The second connector 42 is also provided with a lifting eye 422.

[0076] The boom attitude controller 26 includes a microcontroller, an A / D conversion circuit, a clock circuit, a reset circuit, a potentiometer, a relay, and a power module connected to the microcontroller. The power module converts 12V voltage to 5V voltage to power the microcontroller, potentiometer, and relay. The A / D conversion circuit converts various analog signals into digital signals to provide to the microcontroller. The potentiometer provides preset angle information to the microcontroller. The relay receives control signals from the microcontroller and then controls the hydraulic control system.

[0077] The structure of the boom attitude adjustment control system is as follows: Figure 10 As shown, it mainly consists of three parts: a boom attitude controller, an information acquisition system, and a hydraulic actuator. The information acquisition system returns the detected tilt angle information to the controller. The hydraulic actuator, as a key component of the system, is used to execute the commands issued by the controller to adjust the tilt angle. The boom attitude controller, as the core of the system, controls the operation of the entire system.

[0078] The boom attitude controller, as the core of the system, communicates with the information acquisition system and the PC via a serial port, receiving information from the acquisition system in real time. The integrated control program and algorithm model process the information to achieve real-time control of the actuator.

[0079] To meet requirements and improve scalability, the control board design of the boom attitude controller needs to include several core modules, such as a power module, signal receiving module, program input interface, A / D conversion circuit, and restart circuit. These modules provide basic support for the normal operation of the controller. In addition, the control board should also include auxiliary buttons such as a power switch, signal indicator lights, and a reset switch for user operation and status monitoring. The boom attitude controller needs to transmit data with external devices, requiring the design of CAN bus interfaces, UART interfaces, and signal transceiver interfaces to meet connectivity needs with other devices. Data transmission with the tilt sensor can be achieved via the UART interface, and communication with a PC can be achieved using a CH340 module for more convenient operation and data interaction.

[0080] This invention utilizes the PIC18F258 microprocessor manufactured by Microchip Technology Inc. to design a spray boom attitude controller. The PIC18F258 microcontroller features an advanced reduced instruction set architecture, an enhanced core, 32 KB of flash program memory, on-chip Flash program memory, EEPROM data memory, self-programming capability, an in-circuit debugger, and various internal and external interrupt sources, operating at frequencies up to 40 MHz. It also employs a "Harvard" bus architecture where program and data spaces are completely separated, a design where program and data reside in the same memory space. This architecture reduces the overall cost of the PIC microcontroller while improving operational efficiency.

[0081] This invention utilizes the JY61P tilt sensor manufactured by Shenzhen Weite Technology Co., Ltd. This module employs a high-precision gyro accelerometer, the MPU6050, and reads the measurement data from the MPU6050 via a processor, then outputs it through a serial port. The module has an internal voltage stabilization circuit, making it compatible with 3.3V / 5V embedded systems and easy to connect. Furthermore, the module integrates an attitude solver, which, combined with a dynamic Kalman filter algorithm, can accurately output the current attitude of the boom suspension in dynamic environments, with an attitude measurement accuracy of 0.05 degrees and high stability.

[0082] When spraying pesticides, if the sprayer is positioned on a slope, the plane of the spray boom must be parallel to the plane of the machine body. This results in an angle between the spray boom plane and the horizontal plane of the ground. This angle is the preset angle that needs to be set. An external potentiometer connected to the microcontroller converts the analog signal output by the potentiometer into a digital signal via an AD converter. The program then limits this digital signal to a range of 0°-180°. By rotating the potentiometer, different angle values ​​are read to change the preset angle of the control system. Considering all factors, a TOCOS RV24YN20S potentiometer from Japan is selected, with a total resistance of 10 kΩ, a power supply voltage of 5V, and an electrical angle of 280°.

[0083] The high-clearance sprayer in this invention is powered by a 12V lead-acid battery, while the controller and information acquisition module require a 5V power supply. A 12V to 5V transformer module is selected to convert the voltage to 5V for power supply. To ensure the safety of the power supply circuit, diodes are used to prevent breakdown caused by reverse voltage connection. A capacitor connected in parallel at the input terminal can solve the problem of the control unit restarting due to a sudden voltage drop, thus maintaining the stability of the controller. A reset circuit is designed so that if the power supply voltage becomes abnormal due to the influence of other electrical appliances, it will force a reset.

[0084] The microcontroller of this invention is also connected to an ICSP interface circuit. The ICSP interface, or In-Circuit Serial Programming Interface, consists of five pins. The MCLR pin is used for programming and resetting the microcontroller. During programming, an appropriate voltage is applied to erase, write, or read the microcontroller's internal flash memory. The VDD pin provides power to the microcontroller. GND is the ground pin, and the PGD pin is used to transmit programming data. The programming device transmits data with the microcontroller through this pin, including sending programs and reading data. The PGC pin provides the programming clock signal. The programming device provides a synchronous clock signal to the microcontroller through this pin. The PIC microcontroller can be programmed, burned, and debugged by connecting to the pins of the ICSP interface.

[0085] Pins 17 and 18 of the PIC microcontroller are the transmit and receive pins, respectively. The RX pin of the microcontroller is connected to the TX pin of the tilt sensor. When the spray boom's attitude changes, the tilt sensor sends a digital signal to the attitude controller. The controller decodes the acquired digital information to obtain the angle information. After processing the tilt signal, the controller outputs high and low level signals to control the relay. The PC receives and saves the attitude information for subsequent data processing and research. To facilitate communication between the spray boom attitude adjustment control system and other ECUs of the sprayer, a CAN bus communication circuit is designed and communication nodes are reserved.

[0086] like Figure 11 As shown, the relay is the execution module, active low. The relay's IN1 and IN2 pins are connected to the microcontroller's C0 and C1 pins, respectively. The position of the solenoid directional valve spool can be changed by setting the IN pin, controlling the extension and retraction of the leveling hydraulic cylinder. The power supply module includes a 12V DC power supply for powering the PC, and a 12V to 5V transformer module for directly powering the control module, tilt sensor, and potentiometer.

[0087] When C0 and C1 output high levels, the relay is in the off state, and the solenoid directional valve does not work. When C1 outputs low level and C0 outputs high level, the solenoid directional valve controls the leveling cylinder to retract, and the spray boom rotates to the left. When C1 outputs high level and C0 outputs low level, the solenoid directional valve controls the leveling cylinder to extend, and the spray boom rotates to the right. The analog signal output by the potentiometer, after analog-to-digital conversion, is used to set the expected angle of the spray boom. The leveling controller reads the filtered spray boom tilt angle data through RX, compares this value with the preset angle value, and after PID calculation, issues high and low level signals. The movement direction of the solenoid valve core is controlled by the relay's activation, which in turn controls the extension and retraction of the cylinder piston.

[0088] like Figure 12As shown, the hydraulic control system includes an oil tank 61, a filter 62, a hydraulic pump 63, a pressure gauge 64, a two-position three-way solenoid directional valve 65, and a solenoid relief valve 66 connected in sequence. The two-position three-way solenoid directional valve 65 is connected to the leveling cylinder 22, the lifting cylinder 13, the left-side deployment cylinder 27, and the right-side deployment cylinder 28 respectively through multiple three-position four-way solenoid directional valves 67. The spray bar attitude controller 26 controls the state of the two-position three-way solenoid directional valve (65) and the multiple three-position four-way solenoid directional valves 67, so that the leveling cylinder 22, the lifting cylinder 13, the left-side deployment cylinder 27, and the right-side deployment cylinder 28 complete the corresponding actions.

[0089] like Figures 13 to 17 As shown, a posture control method for a wide-width spray boom of a plant protection machine is described above, employing any one of the aforementioned wide-width spray boom posture adjustment systems, and the control process is as follows:

[0090] After the equipment is started, the tilt sensor collects the tilt angle information of the central spray boom 23 in real time during operation. The spray boom attitude controller 26 subtracts the acquired tilt angle information from the set expected angle to obtain the difference. If the difference is less than the set threshold, the central spray boom 23 does not need to be adjusted. If the difference is greater than the threshold, the spray boom attitude controller 26 adjusts the on / off state of the solenoid valve according to the difference information, changes the direction of the oil circuit and the hydraulic oil flow, and thus changes the extension and retraction of the leveling cylinder, so that the central spray boom 23 is automatically leveled. The above steps are repeated continuously during the adjustment process until the difference is less than the set threshold, and the adjustment process ends.

[0091] The boom attitude controller 26 uses a PID algorithm to perform closed-loop control on the extension of the leveling cylinder 22. The specific process of PID control is as follows: The tilt sensor collects the actual tilt angle information, calculates the error value between the preset tilt angle and the actual tilt angle, multiplies the error value by the proportional coefficient to obtain the output value of the proportional control part, accumulates the calculated error values ​​and multiplies them by the integral time to obtain the output value of the integral control part; multiplies the rate of change of the error value by the derivative time to obtain the output value of the derivative control part, and adds the output values ​​of the proportional control part, integral control part and derivative control part to obtain the final control output signal. The boom attitude controller sends the level signal to the relay according to the final control output signal to control the on / off time and valve core direction of the corresponding solenoid valve of the hydraulic control system.

[0092] When the boom attitude controller 26 employs a PID algorithm, in determining the PID parameters, the integral and derivative times are first set to zero, and only the proportional coefficient is adjusted. By observing the steady-state error value, overshoot, and response speed indicators of the system output, the proportional coefficient is gradually increased or decreased to find a suitable range for automatic boom leveling. Then, integral and derivative control are gradually introduced, and the integral and derivative coefficients are adjusted to further improve the system's response characteristics. φd and φ a These are the preset tilt angle and the actual tilt angle, respectively, with tilt angle errors e(i) and Ui being respectively...

[0093]

[0094]

[0095]

[0096]

[0097] In the formula, K P K is the proportionality coefficient. I K is the integral coefficient; D T is the differential coefficient; T1 is the integration time constant; T D Given the differential time constant, after adjustment, the final PID parameter selected was K. P =5,K I =0.03, K D =1.

[0098] In field operations, when the sprayer encounters uneven terrain, the angle information acquired by the tilt sensor may undergo a step change. This instantaneous and random signal change can affect the leveling accuracy of the spray boom. This study uses a tilt sensor with an accuracy of 0.01°. To improve the accuracy of angle information acquisition, the step pulses of adjacent angle signals are filtered. Therefore, an average filtering algorithm is used in the design of this control system to smooth the original angle signal. To calculate the average value of the sum of signals in each cycle, the algorithm uses the following formula:

[0099]

[0100] In the formula, N is the number of times the angle signal is taken in the signal period; This represents the average value of the obtained angles; The current angle value is obtained by the tilt sensor; the number of cycles N is between 1 and 5, and it is sent to the queue for recursive average filtering. N consecutive sampled values ​​are taken to form a series for arithmetic average calculation, and the accumulated moving average is updated. The average value of each cycle is used as the tilt angle of the spray boom at this moment.

[0101] With the hinge point between the central spray boom bracket 21 and the crossbeam 14 as the center point O of the coordinate system, the z-axis perpendicular to the chassis plane, the axis along the central spray boom bracket 21 as the y-axis, and the forward direction of the sprayer as the x-axis, a Cartesian coordinate system is established. Point O is the hinge point between the central spray boom bracket 21 and the crossbeam 14. Points A and B are the hinge points between the leveling cylinder 22 and the crossbeam 14, and between the leveling cylinder 22 and the central spray boom bracket 21, respectively. The tilt angle β of the central spray boom bracket 21 is the rotation angle of the central spray boom bracket 21 around the x-axis. The relationship between the tilt angle β and the extension / retraction of the leveling cylinder 22 is calculated as follows.

[0102] When the middle spray boom support 21 is in a horizontal position relative to the sprayer, the angle between the middle spray boom support 21 and the crossbeam 14 is:

[0103]

[0104] With the crossbeam as the reference, when the middle spray boom support is at its rightward tilt limit, the maximum rightward tilt angle of the middle spray boom support relative to the sprayer is:

[0105]

[0106] With the crossbeam as the reference, when the middle spray boom support is at its leftward tilt limit, the maximum leftward tilt angle of the middle spray boom support relative to the sprayer is:

[0107]

[0108] The adjustable range of the central spray bar bracket 21 is:

[0109]

[0110] In the formula, This represents the maximum rightward tilt angle of the central spray boom support; This represents the maximum leftward tilt angle of the central spray boom support; θ The angle between the line connecting hinge point AO and hinge point OB; l a The length of the line connecting the hinge point AO is in mm. l b The length of the line connecting the hinge point OB is in mm. l The initial length of the leveling cylinder when the middle spray boom support is horizontal, in mm; l 1. l 2 represents the extension and retraction of the leveling cylinder at the right and left extreme positions, respectively, in mm.

[0111] Response time is a crucial indicator for evaluating the performance of a control system. A shorter response time means the system can respond to input signals more quickly and reach a stable operating state. By calculating the response time, the system's speed, stability, and accuracy can be assessed, determining whether the system meets actual requirements. The central spray boom support needs to respond quickly and stably during leveling; calculating the response time of the attitude control system allows for better optimization of the spray boom attitude control method.

[0112] The preset angle set for the middle spray boom bracket 21 during operation is: φ d The roll angle of the sprayer during operation is φ The difference between the preset angle φd and the roll angle φ maintained at the previous moment is equal to the sum of the tilt angle β of the boom support relative to the sprayer and the adjustment amount Δβ of the boom support relative to the target at the previous moment. Therefore, the adjustment amount of the boom support 21 relative to the sprayer at this moment is... Δ β is:

[0113]

[0114] The angle value that should be controlled at the current moment is:

[0115]

[0116] In automatic leveling mode, the boom support adjusts according to its angle relative to the sprayer body. When the sprayer body tilts to the left, the piston of the leveling cylinder retracts, causing the boom support to adjust to the right to maintain a relatively horizontal state. The corresponding response time is determined by calculating the piston retraction stroke, as shown in the following formula:

[0117]

[0118] When the sprayer body tilts to the right, the piston of the leveling cylinder 22 extends, causing the spray boom bracket to adjust to the left to maintain a relatively horizontal state. The response time is calculated from the piston extension stroke:

[0119]

[0120] In the formula, D is the cylinder diameter of the leveling cylinder, in mm; d The rod diameter for leveling the hydraulic cylinder is measured in mm. The piston extension / retraction amount of the hydraulic cylinder is used for leveling, and the unit is mm; q The flow rate of the hydraulic cylinder is adjusted to be measured in L / min.

[0121] When the automatic leveling adjustment of the spray boom bracket is tilted to the right or left, each 1° rotation is considered to be a consistent extension and retraction of the leveling cylinder. Therefore, the response time for each 1° rotation of the spray boom bracket is:

[0122] .

[0123] To verify the effectiveness of the boom leveling control system, this application also conducted field experiments, selecting multiple sets of experiments with different PID parameters to choose the parameter combination with fast response and stable adjustment. The purpose of the field experiments was to further verify the actual operational effect of the selected parameter combination.

[0124] The experimental platform is an unmanned spraying machine developed based on the Huasheng Taishan 3WP-500G sprayer, equipped with a boom attitude adjustment system. The mechanical structure, hydraulic system, and electrical control system for boom lifting and leveling were designed and studied.

[0125] The experiment designed five test indicators to reflect the regulation performance of the control system: settling time, average nozzle tilt angle, steady-state error, root mean square error, and mean absolute error. Response time refers to the time elapsed from receiving the regulation signal to reaching the desired stable operating state. The main purpose of calculating the settling time is to evaluate the performance and response speed of the control system; its calculation formula is as follows:

[0126]

[0127] In the formula, T Q The control system settling time, measured in seconds; K Q The difference between the points used from the start of system adjustment to the completion of adjustment; f is the data transmission rate, in Hz.

[0128] The steady-state difference is used to represent the overall stability of the system, that is, the ability of the spray boom to maintain stability after adjustment is completed. The average value of the difference from the preset angle is calculated over a 2-second period. The calculation formula is:

[0129]

[0130] In the formula, β e For steady-state error; β k The nozzle tilt angle is at a certain time; Ks is the number of data sampling points when the system adjustment is completed.

[0131] During the experiment, due to the complexity and diversity of the experimental environment and interference from factors inherent to the machine itself, multiple sets of experiments were required to avoid inaccurate results caused by accidental factors. The adjustment effect was evaluated by calculating the average value of the spray boom tilt angle, the root mean square error, and the mean absolute error. The calculation formula is as follows:

[0132]

[0133] In the formula, 1 represents the mean angle of the spray boom; RMSE represents the root mean square error; MAE represents the mean absolute error. The target spray boom tilt angle; N is the total number of samples taken in a single field trial.

[0134] To simulate actual field application conditions, an experimental platform with a height of 0.3m, a length of 10m, and an incline of 8° was constructed to simulate the situation where a sprayer encounters uneven ground while traveling in a straight line. During the experiment, the maximum tilt angle of the sprayer could reach 10°. A schematic diagram of the experiment is shown below. Figure 18 As shown, the sprayer starts at point A and ends at point B. The operator remotely controls the machine to pass through the experimental platform in a straight line at normal operating speed, verifying the effectiveness of the spray boom leveling system.

[0135] A leveling test was conducted according to GB / T24680-2009 "Test Method for Stability of Sprayer Boom in Agricultural Sprayers". In order to analyze the effectiveness of the sprayer's attitude control system, it is necessary to compare the vehicle body tilt angle and the spray boom tilt angle at the same time. The vehicle body tilt angle attitude information of the automatic sprayer can be obtained through the IMU unit of the automatic navigation system, and the spray boom tilt angle information is saved through the information acquisition module. The tilt angle information of the two modules is saved through the PC. Before the experiment, the preset spray boom angle is set to 0°, and the sprayer is operated to pass through the experimental platform.

[0136] Analysis of the sprayer's operating conditions revealed that when the boom tilt angle is 3°, the deviation of the boom tip from the horizontal position is 0.3m. When the boom tilt angle exceeds 3°, it is highly likely to contact the crop or ground, causing damage. Therefore, the response threshold for this experiment was set within 3°. Six groups were taken at 0.5° intervals. The sensor output frequency was 20Hz. After filtering, the response time was 0.8s when the sample value was 8, and 1s when the sample value was greater than 8. The slow boom response time prevented timely leveling, affecting the operational efficiency. Therefore, the experiment was designed with sample values ​​within 8, taking eight groups at 1-degree intervals. This involved recording and analyzing the leveling performance of the control system under different response thresholds n (0.5°, 1°, 1.5°, 2°, 2.5°, 3°) and different average sample values ​​b (1, 2, 3, 4, 5, 6, 7, 8) to obtain the optimal parameter combination.

[0137] Table 1. Test Parameter Combination Table

[0138]

[0139] The experimental results are shown in Table 6.8.

[0140] Table 6.8 Results of Field Test Data Analysis

[0141]

[0142]

[0143] The sensitivity decreases as the response threshold increases, but increases as the sampled value increases. This is mainly due to the following reasons: when the response threshold of the spray boom increases, the sensitivity of the spray boom adjustment decreases. The spray boom stops responding when tilted but the tilt angle is less than the set threshold, thus increasing the error. When the sampled value increases, the vibration error caused by the vehicle body has a smaller impact on the spray boom adjustment due to the existence of averaging filtering, resulting in increased adjustment accuracy.

[0144] When the response threshold is too small, vehicle vibration and bumps will cause the spray boom's tilt angle to fluctuate within a range of 0.5°, resulting in the spray boom being constantly in adjustment mode and increasing adjustment error. Within the response threshold range of 1° to 3°, the automatic leveling tilt angle error increases with the response threshold, and the accuracy gradually decreases.

[0145] like Figure 19 The figures show the curves of the tilt angle change between the sprayer body and the spray boom suspension when the response thresholds are 0.5°, 1°, 1.5°, and 2°. When the response threshold n ≤ 3.0° in the leveling system, the spray boom tilt caused by the step excitation of the road surface can be effectively reduced. The smaller the leveling response threshold n, the shorter the system response time and the smaller the angle change amplitude. When n = 1°, it is the optimal response threshold of the system, with a maximum average absolute error of 0.59°, which can control the spray boom tilt angle within ±1.5°. Furthermore, when the sampled value b = 2.0, the system control response time is short, ensuring the normal operation of the control system in the field.

[0146] The above field experiments yielded a parameter combination with good adjustment effects. This parameter combination was then used in field experiments to study the practical applicability of the spray boom adjustment system. The target of the field experiment was wheat, and the experiment took place during the wheat's greening stage. Required tools included a measuring tape and a stopwatch.

[0147] During the test, a pre-planned test route was established. The sprayer's operating path was a straight line, with rectangular turns at the field ends. The automatic navigation speed was set to 3.6 km / h based on actual operating conditions. The optimal parameters for the spray boom adjustment were selected from field tests: response threshold n=1°, sampling value b=2. The target tilt angle of the spray boom was set to 0°, and its initial roll angle was 0°. The automatic sprayer started from point C (588244.298m, 4074855.007m) and traveled along the planned test route. Figure 20As shown, from point D (588239.221m, 4074855.369m) to E (588214.123m, 4074857.609m) and from E1 (588215.485m, 4074863.247m) to D1 (588240.556m, 4074860.963m), when the sprayer reaches the boundary, it turns at the edge to enter the adjacent row for operation. The different road conditions of the two paths are recorded, and two sets of tests are conducted. The tilt angle information of the spray boom and the sprayer body after the operation of the boom attitude adjustment system is used to verify the leveling performance of the system.

[0148] The experimental results are shown in Table 6.9.

[0149] Table 6.9 Results of Field Test Data Analysis

[0150]

[0151] During the experiment, tilt angle information was recorded via PC at a frequency of 50Hz. Using the roll angle recorded by the vehicle's IMU as a reference, the data in the table shows that the maximum error after leveling the spray boom was 1.53°, the average angle after leveling was 0.13°, the root mean square error was 0.454°, and the mean absolute error was 0.265°. The spray boom angle after leveling was within 0.5° for 70% of the time. This indicates that the automatic spray boom leveling system works normally in the field, automatically leveling the spray boom during operation. Occasionally, the spray boom wobbles during field operations, but it quickly returns to balance. No mis-leveling occurred, and the system operates smoothly and can be used in actual operations. The test spray boom tilt angle changes are as follows: Figure 21 As shown.

[0152] To facilitate experimental analysis, the following experimental indicators were designed for this invention: adjustment completion time, steady-state error, average spray boom tilt angle, root mean square error, and mean absolute error. Field trials showed that the average angle measured by the spray boom tilt angle sensor after leveling was 0.135°, the mean absolute error was less than 0.40°, the root mean square error was less than 0.50°, and the maximum error was 1.53°. The automatic spray boom leveling system functioned normally in the field. Occasionally, there was some swaying when the ground was uneven, but it quickly regained balance, and there was no contact between the spray boom and the crop; the spray boom adjustment was stable.

[0153] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0154] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the posture of a wide boom of a plant protection machine, characterized in that: The posture adjusting system of the wide spraying boom of the plant protection machine comprises a height adjusting assembly (1), a horizontal adjusting assembly (2), a side spraying boom assembly (3) and a hydraulic control system, the height adjusting assembly (1) comprises a lifting oil cylinder (13) and two parallelogram mechanisms fixed at the middle part through a cross bar, one end of the parallelogram mechanism is fixed with a cross beam (14), and the two ends of the lifting oil cylinder (13) are hingedly connected with the cross beam (14) and the cross bar respectively; the horizontal adjusting assembly comprises a middle spraying boom support (21), a leveling oil cylinder (22), a middle spraying boom (23), a spraying boom posture controller (26) and an inclination sensor, the upper part of the middle spraying boom support (21) is hingedly connected with the middle part of the cross beam (14), the lower part is hingedly connected with one end of the leveling oil cylinder (22), the other end of the leveling oil cylinder (22) is hingedly connected with the end of the cross beam (14), the middle spraying boom (23) is fixed on the middle spraying boom support (21) through a pipe clamp (24), and a plurality of spraying heads A (25) are uniformly and spacedly arranged on the middle spraying boom (23), the spraying boom posture controller (26) and the inclination sensor are arranged on the middle spraying boom support (21) and the middle spraying boom (23) respectively, the spraying boom posture controller (26) receives the detection information of the inclination sensor, controls the hydraulic control system to drive the leveling oil cylinder (22) to extend or retract, and then adjusts the inclination angle of the middle spraying boom (23) relative to a reference surface; the two ends of the middle spraying boom support (21) are hingedly connected with the two side spraying boom assemblies (3) respectively, and the unfolding and folding of the two side spraying boom assemblies (3) are controlled through a left side unfolding oil cylinder (27) and a right side unfolding oil cylinder (28) respectively; and the control process is as follows: After the device is started, the inclination sensor collects the inclination information of the middle spraying boom (23) in the working state in real time, the spraying boom posture controller (26) subtracts the obtained inclination information from the set expected angle to obtain a difference value, if the difference value is less than a set threshold value, the middle spraying boom (23) does not need to be adjusted; if the difference value is greater than the threshold value, the spraying boom posture controller (26) adjusts the on-off state of the corresponding electromagnetic valve of the hydraulic control system according to the difference value information, changes the direction of the oil way and the hydraulic oil flow, and then changes the extension and retraction of the leveling oil cylinder (22), so that the middle spraying boom (23) is automatically leveled, and the above steps are repeatedly performed in the adjustment process until the difference value is less than the set threshold value, and the adjustment process is ended; The spraying boom posture controller (26) adopts a PID algorithm to perform closed-loop control on the extension amount of the leveling oil cylinder (22), and the specific process of the PID control is as follows: the inclination sensor collects the actual inclination information, calculates the error value between the preset inclination and the actual inclination, multiplies the error value by a proportional coefficient to obtain the output value of the proportional control part, and accumulates the calculated error value and multiplies it by an integral time to obtain the output value of the integral control part. The rate of change of the error value is multiplied by the differential time to obtain an output value of the differential control part. The output values of the proportional control part, the integral control part and the differential control part are added to obtain a final control output signal. The spray bar attitude controller (26) sends a level signal to a relay according to the final control output signal to control the on-off time and the spool direction of the corresponding electromagnetic valve of the hydraulic control system. In the process of determining the PID parameters, the integral time and the differential time are first set to zero, and only the proportional coefficient is adjusted. By observing the steady-state error value, the overshoot and the response speed indicators of the system output, the proportional coefficient is gradually increased or decreased to find a suitable range for the automatic leveling of the spray bar. Then, the integral and differential controls are gradually introduced, and the integral coefficient and the differential coefficient are adjusted to further improve the response characteristics of the system. If ​ d and ​ a are the preset inclination and the actual inclination, respectively, the inclination error e(i) and Ui are respectively where K P is a proportional coefficient; K I is an integral coefficient; K D is a differential coefficient; T1is an integral time constant; T D is a differential time constant, after adjustment, ultimately determine the selection of PID parameters K P = 5, K I = 0.03, K D = 1. 2.The posture control method of a wide-spray-rod of a plant protection machine according to claim 1, characterized in that: The spray bar posture controller (26) comprises a single-chip microcomputer, an A / D conversion circuit, a clock circuit, a reset circuit, a potentiometer, a relay and a power module connected with the single-chip microcomputer, the power module converts 12V voltage into 5V voltage to supply power for the single-chip microcomputer, the potentiometer and the relay, the A / D conversion circuit converts various analog signals into digital signals to provide the single-chip microcomputer, the potentiometer provides preset angle information for the single-chip microcomputer, and the relay receives a control signal of the single-chip microcomputer to control the hydraulic control system. 3.The posture control method of a wide-spray-rod of a plant protection machine according to claim 1, characterized in that: The hydraulic control system comprises an oil tank (61), a filter (62), a hydraulic pump (63), a pressure gauge (64), a two-position three-way electromagnetic reversing valve (65) and an electromagnetic overflow valve (66) connected in sequence, the two-position three-way electromagnetic reversing valve (65) is communicated with the leveling oil cylinder (22), the lifting oil cylinder (13), the left side unfolding oil cylinder (27) and the right side unfolding oil cylinder (28) through a plurality of three-position four-way electromagnetic reversing valves (67), and the spray bar posture controller (26) controls the states of the two-position three-way electromagnetic reversing valve (65) and the plurality of three-position four-way electromagnetic reversing valves (67) to make the leveling oil cylinder (22), the lifting oil cylinder (13), the left side unfolding oil cylinder (27) and the right side unfolding oil cylinder (28) complete corresponding actions.

4. The attitude control method of a wide-spray boom of a plant-protection machine according to claim 1, characterized in that: The parallel four-bar mechanism comprises lifting rods (11) and vertical fixing sleeves (12), the lifting rods (11) are in the shape of an I-beam, two lifting rods (11) are stacked up and down at intervals, and each end of the two lifting rods (11) is hingedly connected with two ends of a vertical fixing sleeve (12).

5. The attitude control method of a wide-spray boom of a plant-protection machine according to claim 1, characterized in that: The side spray bar assembly (3) comprises an inner pipe (31) and an outer sleeve pipe (32) sleeved with each other, the inner pipe (31) and the outer sleeve pipe (32) are both provided with spray heads B (36) at intervals, one end of the outer sleeve pipe (32) is fixedly provided with a first connecting piece (33), both ends of the middle spray bar support (21) are provided with sleeves, the first connecting piece (33) is provided with a shaft (34), the shaft (34) is inserted into the sleeve, and the upper portion of the first connecting piece is further provided with a convex column (37), the convex column (37) is hingedly connected with the corresponding left side unfolding oil cylinder (27) or right side unfolding oil cylinder (28). 6.The posture control method of a wide-spray-rod of a plant protection machine according to claim 1, characterized in that: The outer end of the side spray bar assembly (3) is further provided with an end spray bar assembly (4), the end spray bar assembly (4) comprises a terminal spray bar (41), a second connecting piece (42) and spray heads C (43), a plurality of spray heads C (43) are fixed on the terminal spray bar (41) at intervals, one end of the second connecting piece (42) is fixed with the side spray bar assembly (3), and the other end is fixed with the terminal spray bar (41).

7. The attitude control method of a wide-spray boom of a plant-protection machine according to claim 1, characterized in that, The center point O of the coordinate system is the hinge point of the middle spray rod support (21) and the cross beam (14), the z axis is perpendicular to the vehicle chassis plane, the y axis is the axis of the middle spray rod support (21), and the x axis is the forward direction of the spraying machine; points A and B are the hinge points of the leveling cylinder (22) and the cross beam (14) and the leveling cylinder (22) and the middle spray rod support (21) respectively; the inclination angle β of the middle spray rod support (21) is the rotation angle of the middle spray rod support (21) around the x axis, and the relationship between the inclination angle β and the extension amount of the leveling cylinder (22) is calculated as follows, When the middle spray rod support (21) is in a horizontal position relative to the spraying machine, the included angle between the middle spray rod support (21) and the cross beam (14) is: When the middle spray rod support (21) is in a right-tilting limit position relative to the cross beam (14), the maximum right-tilting angle of the middle spray rod support (21) relative to the spraying machine is: When the middle spray rod support (21) is in a left-tilting limit position relative to the cross beam (14), the maximum left-tilting angle of the middle spray rod support (21) relative to the spraying machine is: That is, the adjustable range of the middle spray rod support (21) is: In the formula, is the maximum right tilt angle of the middle spray boom support (21); is the maximum left tilt angle of the middle spray boom support (21); The preset angle of the middle spray rod support (21) during operation is φd, the roll angle of the spraying machine during operation is φ, the difference between the preset angle φd and the roll angle φ at the previous moment is equal to the sum of the inclination angle β of the spray rod support (21) relative to the spraying machine and the adjustment amount Δβ of the spray rod support (21) relative to the target, and then the adjustment amount Δβ of the inclination angle of the spray rod support (21) relative to the spraying machine is: is the included angle between the connecting line of the hinge point AO and the hinge point OB; l a is the length of the connecting line of the hinge point AO, in mm; l b is the length of the connecting line of the hinge point OB, in mm; l is the initial length of the leveling oil cylinder (22) when the middle spray boom support (21) is horizontal, in mm; l 1, l 2 are the extension and retraction amounts of the leveling oil cylinder (22) when the right and left limit positions, respectively, in mm. 8.The posture control method of a wide-spray-rod of a plant protection machine according to claim 7, wherein, The angle value that should be controlled to change at the current moment is: The spray rod support (21) is adjusted according to the angle relative to the vehicle body of the spraying machine in the automatic leveling mode, when the vehicle body of the spraying machine tilts to the left, the piston of the leveling cylinder (22) is retracted, the spray rod support (21) is adjusted to the right to maintain a relative horizontal state, the response time is determined by calculating the retraction stroke of the piston, and the calculation formula is as follows: When the vehicle body of the spraying machine tilts to the right, the piston of the leveling cylinder (22) is elongated, the spray rod support (21) is adjusted to the left to maintain a relative horizontal state, and the response time is calculated by the elongation stroke of the piston: When the automatic horizontal adjustment of the spray rod support (21) is right-tilting or left-tilting, the extension amount of the leveling cylinder (22) is consistent for every 1° rotation, so the response time of the spray rod support (21) is: D is the cylinder diameter of the leveling oil cylinder (22) in mm; d D is the rod diameter of the leveling oil cylinder (22) in mm; D is the piston stroke of the leveling oil cylinder (22) in mm; q D is the flow of the leveling oil cylinder (22) in L / min; ​ 。

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