Airflow dynamic distribution and pressure stabilization regulation and control method for parallel pipelines of air-aspiration type seeding machine

Abstract

The invention relates to a parallel pipeline airflow dynamic distribution and pressure stabilization regulation and control method for an air suction type seeder. A system comprises a signal bus, a power bus, a control module, a man-machine interaction module, a branch pipe flow sensor, a pneumatic pipeline system, a fan control module, a power module and a header pipe air pressure sensor. The pneumatic pipeline system comprises a header pipe and a plurality of parallel branch pipes; the number of the branch pipe flow sensor is one, and inlet flow data of the branch pipe on the leftmost side are collected in real time. The header pipe air pressure sensor is responsible for monitoring the inlet negative pressure value of the header pipe in real time; the state of each branch pipe of the parallel pipelines is predicted through a branch pipe flow prediction model embedded in the control system, and through a PID regulation and control algorithm and a dynamic feedback optimization strategy, a control signal is output to a fan regulation and control module, the output power and the rotating speed of a fan are dynamically regulated, and distribution of branch pipe airflow flow and optimal control of main pipe negative pressure are achieved. The invention has the advantages of simple operation, convenient expansion and high intelligent degree, and belongs to the technical field of seeding.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of seeding technology in agricultural machinery, and particularly relates to a parallel pipeline air flow dynamic distribution and stable pressure regulation and control method for air seeding machine. BACKGROUND

[0002] At present, air seeding machine is developing towards multi-row control, precision seeding and high-speed operation, and the supporting air system mostly adopts the form of "single fan + multi-branch pipeline" combination for centralized air supply. However, due to the parallel installation mode of multi-row seeders, the current air supply system pipeline has the problems of poor air flow distribution uniformity of each branch pipe caused by different air flow transmission path lengths and large total pipe pressure amplitude caused by air flow collection; and further causes the problems of inconsistent negative pressure suction of each row of seeders, uneven seeding amount and poor operation stability during seeding stage, which seriously restricts the precision and reliability of seeding operation.

[0003] At the same time, due to the fact that the existing fan fails to introduce real-time air flow state feedback or branch pipe flow prediction mechanism, the current air supply system fan mostly runs at a fixed speed or is manually tested and adjusted before seeding, the control and regulation method is single, and under the dynamic conditions of operation scene change, pipeline structure change and air seeding machine / seeders switching, the system cannot dynamically distribute and regulate the pipeline real-time flow and pressure according to the pipeline air flow information. Therefore, there is an urgent need for a technology that can real-time collect branch pipe air flow state and stabilize the total pipe pressure loss, dynamically regulate the fan rotation through accurate mathematical model calling, and further realize adaptive closed-loop control of the whole system. SUMMARY

[0004] In view of the technical problems in the prior art, the purpose of the present application is to provide a parallel pipeline air flow dynamic distribution and stable pressure regulation and control method for air seeding machine, which has simple system structure, fast response and is suitable for large-scale production operation scenes such as rice, wheat, corn, soybean and rape air seeding machine.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A kind of air suction type seeding machine parallel pipe gas flow dynamic distribution and stable pressure control method, system includes signal bus, power bus, control module, man-machine interaction module, branch pipe flow sensor, gas pipeline system, fan control module, power module, total pipe gas pressure sensor;Gas pipeline system includes a total pipe and multiple parallel branch pipes;The number of branch pipe flow sensor is one, and the inlet flow data of leftmost branch pipe is collected in real time;Total pipe gas pressure sensor is responsible for real-time monitoring the inlet negative pressure value of total pipe;Through the branch pipe flow sensor installed on branch pipe and the total pipe gas pressure sensor installed on total pipe, the pipeline gas flow state is acquired in real time, the state of each branch pipe of parallel pipeline is predicted by the branch pipe flow prediction model embedded in control system, and control signal is output to fan control module by PID control algorithm and dynamic feedback optimization strategy, the output power and speed of fan are dynamically adjusted, to realize the distribution of branch pipe gas flow and the optimal control of total pipe negative pressure.

[0007] As a preferred, a kind of air suction type seeding machine parallel pipe gas flow dynamic distribution and stable pressure control method, including the following steps:

[0008] Step one, user starts system by man-machine interaction module, and according to the positive pressure channel mouth structure parameter of current seeding crop special seed metering device, the structure parameter of multiple branch gas pipeline system is input, and is transmitted to control module by serial communication mode;

[0009] Step two, control module receives structure parameter information from man-machine interaction module, and combines the real-time inlet flow value of branch pipe equipped with branch pipe flow sensor, calls preset branch pipe flow prediction model, to prepare for subsequent calculation;

[0010] Step three, total pipe gas pressure sensor carries out real-time monitoring to the gas pressure change at the inlet of total pipe, and sends detection data to control module by signal bus;

[0011] Step four, branch pipe flow sensor monitors the real-time inlet flow of branch pipe equipped with branch pipe flow sensor, and synchronously transmits data to control module by signal bus;

[0012] Step five, control module comprehensively step four branch pipe flow data and step three total pipe gas pressure data, calculates the inlet flow value and inlet flow variation coefficient of the rest each branch pipe based on built-in branch pipe flow prediction model, and transmits the calculation result to man-machine interaction module, realizes the visual display of the real-time flow of each branch pipe of gas pipeline system, inlet flow variation coefficient and the pressure information of total pipe, to facilitate user real-time monitoring system operating state;

[0013] Step six, the control module according to the real-time flow data of the branch pipe in step four and the model calculation result in step five, and with the minimum variation coefficient of the inlet flow and the minimum fluctuation of the total pipe pressure as the double regulation targets, generates the fan speed regulation instruction through the incremental PID regulation algorithm and sends it to the fan control module;

[0014] Step seven, the fan control module receives the regulation signal sent by the control module and dynamically adjusts the running state of the fan, so as to realize the reasonable distribution of the airflow of each branch pipe of the pneumatic pipeline system and the stable control of the total pipe pressure.

[0015] As a preferred, in step five, the real-time inlet flow value of the branch pipe measured by the branch flow sensor is Q1, and the inlet flow Q i The calculation formula is:

[0016]

[0017] In the formula, x is a variable factor, f(x) is a function model under the variable factor, and x takes any factor in Q1, d, l, δ, γ, Δ, and D. When x is determined as a certain factor, the function expression product of the remaining factors together constitutes a constant term λ. At this time, ξ is the error compensation coefficient for improving the calculation accuracy of the formula; Q1: the real-time inlet flow value of the leftmost branch pipe, unit m 3 ·s -1 ; d is the inner diameter of the branch pipe, unit mm; l is the length of the branch pipe, unit mm; δ is the branch pipe spacing, unit mm; γ is the inner diameter of the header, unit mm; Δ is the length of the total pipe, unit mm; D is the inner diameter of the total pipe, unit mm;

[0018] The calculation formula of the inlet flow variation coefficient is:

[0019]

[0020] In the formula, n is the number of branch pipes; j is the serial number of each branch pipe, arranged from left to right, taking 1-10; Q j is the inlet flow of each branch pipe, unit m 3 ·s -1 ; Q m is the average value of the inlet flow of each branch pipe, unit m 3 ·s -1 .

[0021] As a preferred, in step six, the fan speed regulation algorithm is designed by using the standard incremental PID algorithm, and the control signal generation process includes:

[0022] (1) Error calculation: the deviation of the branch flow variation coefficient and the total pipe pressure deviation are weighted and fused to generate a composite error signal e c (k):

[0023] e c (k) = a e flow (k) + b e pressure (k),

[0024] wherein e flow (k) represents the current time branch flow coefficient of variation deviation, which is a set value - a measured value; e pressure (k) represents the current time total pipe pressure deviation, which is a target value - a measured value; the weight coefficients a and b are dynamically adjusted according to the system priority;

[0025] (2) PID output: an incremental PID control algorithm is used to calculate the fan speed adjustment amount Au:

[0026]

[0027] wherein e c (k) represents the current time compound error signal deviation, which is a set value - a measured value; e c (k-1) represents the previous time compound error signal deviation, which is a set value - a measured value; e c (k-2) represents the previous time compound error signal deviation based on e c (k-1), which is a set value - a measured value; T d , T i , and T are differential time constant, integral time constant, and sampling period, respectively, and the values of P, I, and D are dynamically adjusted according to the system priority.

[0028] As a preferred, the signal bus is used for data communication and control instruction transmission; the power bus is used for stable DC power transmission; the control module is used for system information receiving, data processing, and control instruction sending; the human-computer interaction module is used for realizing information interaction between the user and the control module; the pneumatic pipeline system is used for air flow transmission and distribution, and is the core execution mechanism of air pressure regulation; the fan control module is responsible for receiving the control instruction sent by the control module and real-time regulating the fan operation state; the power module is used for providing stable power output, and has overvoltage and overcurrent protection functions; the total pipe air pressure sensor transmits data to the control module through a wired way, which is used as reference data for the control module to judge whether the fan needs further regulation.

[0029] As a kind of preferred, pneumatic pipeline system includes branch pipe tee, branch pipe, manifold connecting pipe, main pipe tee, main pipe, branch pipe inlet flow measuring pipe, manifold end closure, manifold end connecting pipe, negative pressure measuring pipe, bellows, clamp, fan, pitot tube, rubber hose;Pneumatic pipeline system includes main pipe, manifold and branch pipe three main body architecture;Manifold includes branch pipe tee, manifold connecting pipe, manifold end closure and manifold end connecting pipe, manifold connecting pipe is used to connect adjacent branch pipe tee, and manifold end connecting pipe is arranged on the outside of two end branch pipe tee, and is blocked by manifold end closure;Branch pipe is connected with the passage of branch pipe tee which is perpendicular to the direction of manifold by equidistant parallel layout mode;Main pipe is arranged at the middle position of manifold, is connected with manifold by main pipe tee, is connected with fan inlet passage by the series connection of negative pressure measuring pipe and bellows;Bellows is fixed to the outlet of negative pressure measuring pipe and fan inlet by clamp;Branch pipe inlet flow measuring pipe is arranged on the leftmost branch pipe, and branch pipe flow sensor is installed on branch pipe inlet flow measuring pipe;Negative pressure measuring pipe, pitot tube, rubber hose and main pipe air pressure sensor are sequentially connected.

[0030] As a kind of preferred, branch pipe flow sensor adopts thermal mode induction principle to obtain the real-time inlet flow of branch pipe, is vertically arranged at the airflow inlet of branch pipe by branch pipe inlet flow measuring pipe, and data is transmitted to control module by wired mode;Main pipe air pressure sensor adopts differential pressure principle to measure the real-time negative pressure of main pipe outlet, and data is transmitted to control module by wired mode.

[0031] As a kind of preferred, signal bus adopts RS485 communication protocol to complete data communication;Power bus is configured according to system power;Power module adopts battery pack, is equipped with overvoltage, overcurrent, short-circuit protection circuit and power state real-time display function, and provides continuous and reliable direct-current power for control module, man-machine interaction module, branch pipe flow sensor, fan control module and main pipe air pressure sensor.

[0032] As a kind of preferred, control module adopts STM32 single-chip microcomputer as core processor, is responsible for receiving and processing the airflow information of each signal input of system, branch pipe flow sensor and main pipe air pressure sensor gathering pipeline;Control module processes the structure parameters of multi-branch pneumatic pipeline system input by man-machine interaction module.

[0033] As a kind of preferred, man-machine interaction module adopts touch screen or tablet, carries out string data transmission with control module by wired mode, and directly shows system running parameters to user by serial screen form.

[0034] The present application has the following advantages:

[0035] 1. The invention only arranges two high-precision sensors at the main pipe and branch pipe, realizes the double optimization control of the main pipe air pressure stability and the branch pipe flow uniformity in the multi-branch parallel pipeline system through the mathematical model and PID control algorithm embedded in the control module combined with real-time air pressure and flow data. This method not only reduces the number of control devices and control logic complexity, significantly reduces the system manufacturing and maintenance costs, but also improves the reliability and applicability of the system.

[0036] 2. Clear control target and optimized control logic: The invention takes "uniform distribution of branch pipe flow" as the core control target, realizes the efficient coordination of multi-branch system parallel pipeline branch flow with the help of real-time flow monitoring data of a branch pipe combined with mathematical prediction model and PID regulation; the main pipe air pressure is used as a feedback index for determining whether the fan has run to a relatively stable state after the uniform distribution of branch pipe flow, rather than being the main control object, thereby avoiding the absolute dependence on the main pipe air pressure and improving the stability and response efficiency of the control.

[0037] 3. Advanced fan control method and fast response speed: The invention uses a DC fan as the core execution unit, which can quickly respond to control signals and has the advantages of high adjustment precision and fast feedback response. The entire operation process does not require manual intervention, realizing automation and high efficiency in the operation process. The DC fan control method of the invention is more suitable for various seeding operation scenes and has good expansibility and universality.

[0038] 4. Flexible system structure design and strong adaptability: In terms of system structure, the invention adopts a symmetrical parallel layout and a detachable combination structure design. The structure parameters of key components such as manifold, branch pipe and main pipe can be quickly replaced and adjusted, which can flexibly match the seed discharge mechanism of different types of seeders and is suitable for various application scenarios from small test equipment to large seeders, meeting the production needs of large-scale and standardization.

[0039] 5. Air pressure fluctuation prediction mechanism and optimization of control strategy: In view of the problems of long transmission path, slow fan response and control lag in the multi-branch air supply system of traditional air-assisted seeders, the invention introduces a differential pressure type negative pressure sensor at the end of the main pipe to capture the fluctuation signal at the air outlet in real time, and the control module quickly identifies and predicts the judgment. The control module issues control instructions in advance according to the prediction results, accurately adjusts the fan operating state combined with the PID algorithm, significantly reduces the fan speed fluctuation and repeated control phenomenon, and further improves the stability and energy efficiency of the system operation.

[0040] 6. The control module integrates functions and optimizes algorithms: The control module in the present application not only has basic signal acquisition and execution functions, but also integrates three control logics of branch flow prediction model, PID control algorithm and dynamic feedback optimization strategy. Through real-time data fusion processing of the branch flow sensor and the total pipe gas pressure sensor, the control module can realize dynamic prediction and instruction adjustment of the fan running state, reduce unnecessary start and stop and speed fluctuation of the fan, and make early response and compensation adjustment before the system deviation, which significantly improves the intelligent level and energy saving performance of the whole machine.

[0041] 7. Intelligent visual and adjustable function of human-computer interaction module: The human-computer interaction module is designed based on a serial port screen system and supports dynamic display function of branch flow uniformity index (such as coefficient of variation CV); users can not only control the pipeline airflow state in real time, but also customize wind pressure adjustment threshold, control frequency and other parameters to meet the seeding needs of different crops and different models, improve the system adaptability and use experience.

[0042] 8. Power supply stability and system safety guarantee mechanism of power module: The direct current power supply system of the present application is provided with voltage fluctuation protection, power reverse connection protection and other safety measures to effectively avoid system misoperation caused by power supply interference. At the same time, it supports replaceable power supply interface design, adapts to 12V / 24V / 48V different voltage levels of seeding equipment, ensures stable operation of the gas supply system under different working conditions, and improves the universality and reliability of the whole machine.

[0043] 9. Integrated adaptive design of module and pipeline structure: The control module, power module and pneumatic pipeline system adopt modular integrated design scheme, which can be directly assembled in the standard installation position of the seeding machine rack, the internal wiring is short and the signal transmission delay is low, avoiding the problems of inconsistent response and signal interference caused by distributed installation in traditional equipment.

[0044] 10. The present application integrates and optimizes control logic, intelligently upgrades interaction mode, protects power supply system, and deeply couples with airflow pipeline system, to build a gas supply control system with higher performance, higher adaptability and stronger scalability, which realizes the transformation from "traditional function superposition" to "innovative function integration".

[0045] 11. The present application adopts modular programming and hardware assembly method, cooperates with RS485 communication protocol, and has strong system compatibility, reliability, expandability and anti-interference ability, which can effectively adapt to the farmland operation environment, and help users to make targeted adjustment and expansion development according to actual operation needs. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a hardware composition schematic diagram of the present application.

[0047] Figure 2 is the schematic diagram of the pneumatic pipeline system structure of the present application.

[0048] Figure 3 is the schematic diagram of the man-machine interface of the present application.

[0049] Figure 4 is the operation flow chart of the control system of the present application.

[0050] The various labels in the figure are: 1 - signal bus, 2 - power bus, 3 - control module, 4 - man-machine interaction module, 5 - branch pipe flow sensor, 6 - pneumatic pipeline system, 7 - fan control module, 8 - power module, 9 - main pipe air pressure sensor, 601 - branch pipe tee, 602 - branch pipe, 603 - manifold connecting pipe, 604 - main pipe tee, 605 - main pipe, 606 - branch pipe inlet flow measuring pipe, 607 - manifold end cap, 608 - manifold end connecting pipe, 609 - negative pressure measuring pipe, 610 - corrugated pipe, 611 - clamp, 612 - fan, 613 - pitot tube, 614 - rubber hose. DETAILED DESCRIPTION

[0051] The present application will be further described in detail below in combination with specific embodiments.

[0052] From Figure 1 , 2 it can be seen that a kind of pneumatic seeding machine parallel pipeline air flow dynamic distribution and stable pressure regulation and control method, system includes signal bus 1, power bus 2, control module 3, man-machine interaction module 4, branch pipe flow sensor 5, pneumatic pipeline system 6, fan control module 7, power module 8 and main pipe air pressure sensor 9. Wherein, pneumatic pipeline system 6 is the core executive mechanism that entire system carries out air flow transmission and distribution, including branch pipe tee 601, branch pipe 602, manifold connecting pipe 603, main pipe tee 604, main pipe 605, branch pipe inlet flow measuring pipe 606, manifold end cap 607, manifold end connecting pipe 608, negative pressure measuring pipe 609, corrugated pipe 610, clamp 611, fan 612, pitot tube 613 and rubber hose 614. Figure 2 As shown, there are 10 branch pipes in total, numbered 1-10, and the branch pipe with branch pipe inlet flow measuring pipe is branch pipe 1, numbered in order.

[0053] In this embodiment, the control module 3 is used to receive and process signal inputs from various modules and sensors within the system, including the structural parameters of the multi-branch pneumatic pipeline system input by the human-computer interaction module 4, the real-time inlet flow data of the branch pipes collected by the branch pipe flow sensor 5, and the outlet negative pressure information of the main pipe 605 collected by the main pipe air pressure sensor 9. The control module 3 comprehensively analyzes the above information, calls the corresponding accurate prediction model according to the specific pipeline structure parameter value, calculates the inlet flow of each branch pipe and the inlet flow variation coefficient of the branch pipe using the matching operation logic, and takes the minimization of the branch pipe inlet flow variation coefficient and the minimization of the main pipe pressure fluctuation as the dual regulation and control targets. The fan speed regulation instruction is generated through the incremental PID regulation and control algorithm, so as to determine the appropriate fan speed and generate the corresponding control signal to drive the fan control module 7 to dynamically regulate the operation state of the fan 612. At the same time, the control module 3 also controls the human-computer interaction interface to display the inlet flow of each branch pipe, the inlet flow variation coefficient of the branch pipe, and the main pipe negative pressure information in real time. The control module 3 and the human-computer interaction module 4 communicate through a TTL serial port. Preferably, the control module 3 uses a single-chip microcomputer with a model number of STM32F103ZET6, which has strong data processing and control instruction output capabilities and can meet the real-time and stability requirements of the system.

[0054] In this embodiment, the human-computer interaction module 4 is used to realize the information interaction between the user and the control module 3, and intuitively displays the key operation parameters of the system to the user through the human-computer interaction interface. Figure 3 It can be seen that the interface developed by the human-computer interaction module 4 includes a parameter setting block, a working state block, and four function keys of start, stop, reset, and save. The parameter setting block is used to input the structural parameters of the gas supply pipeline system, including the main pipe inner diameter, the main pipe length, the manifold inner diameter, the branch pipe inner diameter, the branch pipe length, and the branch pipe spacing. The working state block is used to display the inlet flow of each branch pipe (branch pipes 1-10), the branch pipe flow variation coefficient, and the main pipe pressure in real time. After the user clicks the “start” key, the user can enter the multi-branch pipeline geometric structure parameters in the parameter setting block. After clicking the “stop” key, the parameter setting interface will be locked, and the user cannot input new parameters. After clicking the “reset” key, all the parameters input by the user will be cleared. After clicking the “save” key, the input structural parameters will be saved and used as the basic data for the current stage air flow calculation and control strategy generation. Through the above structural parameter setting and real-time information display of the operation state, the human-computer interaction module 4 effectively realizes the data transmission and function cooperation with the control module 3. Preferably, the human-computer interaction module 4 uses a touch screen.

[0055] In this embodiment, the branch pipe flow sensor 5 is used to collect the inlet flow value of the branch pipe 1 in real time, and transmit the collected data to the control module 3 through the RS485 bus mode; after receiving the real-time flow data, the control module 3 combines the set pipeline structure parameters, calls the built-in mathematical prediction model, and dynamically calculates and estimates the inlet flow of the remaining branch pipes; after completing the flow prediction, the control module 3 transmits the predicted inlet flow parameters of each branch pipe and the related calculation results (including the branch pipe flow variation coefficient, etc.) to the human-computer interaction module 4, realizing the visual display of the real-time flow information of each branch pipe; preferably, the branch pipe flow sensor 5 adopts a pipeline measurement special device, which is suitable for the continuous operation demand in outdoor operation environment, and the measurement error is less than 0.02%.

[0056] In this embodiment, the branch pipe tee pipe and the main pipe tee pipe of the pneumatic pipeline system can be selected from equal-diameter or different-diameter tee pipes, the branch pipe tee pipe and the main pipe tee pipe have multiple different models, and all adopt PVC standard pipes meeting the needs of agricultural production, so that the pipelines with different structure parameters can be flexibly replaced and assembled according to actual production needs. The initial inner diameter size of the main pipe of the pneumatic pipeline system is 0.0426 m, and the initial length is 0.25 m; the initial inner diameter size of the collecting pipe connecting pipe is 0.057 m, and the length of the collecting pipe end connecting pipe is 0.1 m; the initial inner diameter size of the branch pipe is 0.034 m, and the initial length is 0.15 m; the distance between adjacent branch pipes is 0.25 m, and the initial flow target monitoring value of the branch pipe 1 is 0.0027 m 3 -1 .

[0057] In this embodiment, the fan control module 7 is used to receive the control instruction sent by the control module 3, and to dynamically control the speed of the fan 612 in real time according to the received fan speed adjustment parameter, so as to ensure the stable and uniform flow of the airflow in the multi-branch pipeline of the pneumatic pipeline system, and to meet the continuity and responsiveness requirements of the negative pressure air supply for the seeding operation; preferably, the fan control module adopts a single-chip microcomputer with a model of STM32F103C8T6.

[0058] In this embodiment, the power module 8 includes an external power supply, a voltage reduction / stabilization device, and an overvoltage / overcurrent protector, and is mainly used to provide stable and reliable DC power output for the whole system; the module provides the required electric energy to the key control units such as the control module 3, the human-computer interaction module 4, the branch pipe flow sensor 5, the fan control module 7, and the main pipe air pressure sensor 9 through a multi-path power supply mode, and ensures the normal operation of each module and the stability of the whole system; preferably, the external power supply adopts an independent battery pack to provide 48V, 24V or 12V DC stable voltage for the system, which can be flexibly configured according to different operation needs, and is suitable for the continuous power supply demand in outdoor operation environment.

[0059] ​In this embodiment, the total pipe gas pressure sensor 9 is used to monitor the negative pressure value at the total pipe inlet in real time. The sensor is based on the L-shaped Pitot tube combined with differential pressure measurement principle, obtains the dynamic negative pressure data of the airflow inside the total pipe, and transmits the measurement results to the control module 3 through the RS485 bus mode, as an important basis for judging whether further regulation and control of the fan operating state is needed. Preferably, the total pipe gas pressure sensor adopts an industrial-grade sensing device specially used for pipeline gas pressure measurement, has good environmental adaptability, and its measurement accuracy can reach ±1.5%, which can meet the needs of multi-branch gas supply system for pressure detection stability and responsiveness.

[0060] In this embodiment, the control module 3 calculates the remaining branch inlet flow and the branch inlet flow variation coefficient according to the geometric structure parameters of the multi-branch pipeline of the pneumatic pipeline system 6 and the real-time inlet flow value of the branch pipe 1. The remaining branch inlet flow Q i The calculation formula is:

[0061]

[0062] In the formula, x is a variable factor, f(x) is a function model under the variable factor, and x takes any factor in Q1, d, l, δ, γ, Δ, and D. When x is determined as a certain factor, the function expressions of the remaining factors jointly form a constant term λ. At this time, ξ is an error compensation coefficient for improving the calculation accuracy of the formula. Q1: the real-time inlet flow value of the leftmost branch pipe, unit m 3 ·s -1 ; d is the inner diameter of the branch pipe, unit mm; l is the length of the branch pipe, unit mm; δ is the branch pipe spacing, unit mm; γ is the inner diameter of the header, unit mm; Δ is the length of the total pipe, unit mm; D is the inner diameter of the total pipe, unit mm;

[0063] In this embodiment, when x is determined as a certain factor in Q1, d, l, δ, γ, Δ, and D, such as x=Q1, f(x) is f(Q1), and the function expressions of the remaining non-variable factors d, l, δ, γ, Δ, and D jointly form a constant product term λ, i.e. λ=f(d)f(l)f(δ)f(γ)f(Δ)f(D). At this time, ξ is an error compensation coefficient for improving the calculation accuracy of the formula, and the specific value of ξ is shown in the table. When Q1 is a variable, f(x)=f(Q1)=-1.9729×10 -9 (ρQ1 / μL) 4 +1.37541×10 -5 (ρQ1 / μL) 3 -0.033749(ρQ1 / μL )2 +46.3539(ρQ1 / μL)-10567.1, f(Q1) in Q1 is 0.0009-0.0045m 3 ·s -1varies within the range of 0.1 to 0.5, at which time λ = f(d)f(l)f(δ)f(γ)f(Δ)f(D) is a constant value, where the specific functional expressions for f(d), f(l), f(δ), f(γ), f(Δ), f(D) are:

[0064] f(d) = -9.93827 x 10 6 (d / L) 4 + 9.27221 x 10 6 (d / L) 3 - 1.69553 x 10 6 (d / L) 2 - 598379 (d / L) + 189809;

[0065] f(l) = -54214.8 (l / L) 4 + 325289 (l / L) 3 - 716313 (l / L) 2 + 684632 (l / L) - 216648;

[0066] f(δ) = 2710.83 (δ / L) 4 - 21686.8 (δ / L) 3 + 62858.8 (δ / L) 2 - 77939.8 (δ / L) + 56929.3;

[0067] f(γ) = -7.83082 x 10 6 (γ / L) 4 + 1.94696 x 10 7 (γ / L) 3 - 1.78177 x 10 7 (γ / L) 2 + 7.0961 x 10 6 (γ / L) - 1.01285 x 10 6 ;

[0068] f(Δ) = 32528.6 (Δ / L) 4 - 249386 (Δ / L) 3 + 707498 (Δ / L) 2 - 880476 (Δ / L) + 427574;

[0069] f(D) = -3.51961 x 10 6 (D / L) 4 + 7.60284 x 10 6 (D / L) 3 - 5.97048 x 10 6 (D / L)2 +2.0204x10 6 (D / L)-227064.

[0070] And the relevant values of d, l, δ, γ, Δ, D in the formula can be determined according to the basic size data of the pipeline. At this time, when the specific flow distribution of the branch pipe 2-10 is predicted, the error compensation coefficient ξ of the branch pipe 2-10 can be respectively 1.00002, 0.99971, 0.99206, 1.00053, 0.99985, 0.99973, 1.00008, 1.01268, 0.99927.

[0071] When x=d, f(x) is f(d), at this time Q1 is a constant, and λ is the product of the equation of the remaining non-variable elements including Q1, that is, λ=f(Q1)f(l)f(δ)f(γ)f(Δ)f(D). When d is a variable, f(x)=f(d)=-9.93827x10 6 (d / L) 4 +9.27221x10 6 (d / L) 3 -1.69553x10 6 (d / L) 2 -598379(d / L)+189809, f(d) changes in the range of d=0.0194-0.036m, at this time λ=f(Q1)f(l)f(δ)f(γ)f(Δ)f(D) is a constant, and the specific function expressions of f(Q1), f(l), f(δ), f(γ), f(Δ), f(D) are the same as before. The relevant values of Q1, l, δ, γ, Δ, D in the formula are determined according to the basic data of the pipeline. At this time, when the specific flow distribution of the branch pipe 2-10 is predicted, the error compensation coefficient ξ of the branch pipe 2-10 can be respectively selected in the corresponding 21969.5840-21987.4521, 27437.1898-27444.4839, 36089.1258-36484.0778, 50677.4851-50753.0387, 50812.4510-50826.2709, 36699.3045-36739.6089, 27168.2259-27198.4597, 21841.4516-22147.2313, 18924.4567-18936.2805, etc. according to the actual situation.

[0072] Table 1. Value of ξ

[0073]

[0074] The calculation formula of the inlet flow variation coefficient of each branch pipe is:

[0075]

[0076] In the formula, n is the number of branches; j is the serial number of each branch, arranged from left to right, ranging from 1 to 10; Q j The inlet flow rate of each branch pipe is expressed in cubic meters per second (m³). 3 ·s -1 Q m This is the average flow rate at the inlet of each branch pipe, in m³. 3 ·s -1 .

[0077] Preferably, the applicable parameter range for multi-branch pneumatic pipeline systems includes: the applicable range for the real-time flow rate Q at the inlet of branch pipe 1 is 0.0009-0.0045 m³ / h. 3 ·s -1 The applicable ranges for the following structural parameters are: branch pipe inner diameter d: 0.0194-0.036m; branch pipe length l: 0.1-0.2m; branch pipe spacing δ: 0.2-0.3m; manifold inner diameter γ: 0.0426-0.0814m; main pipe length Δ: 0.2-0.3m; and main pipe inner diameter D: 0.0426-0.057m. Within these ranges, the mathematical prediction model called by control module 3 can dynamically calculate the inlet flow of the remaining branch pipes. The error between the predicted value and the actual measured value is controlled within 10%, demonstrating good adaptability and accuracy.

[0078] Depend on Figure 4 As can be seen, in this embodiment, the method for dynamic distribution and pressure regulation of airflow in the parallel pipeline of the air-suction seeder includes the following steps:

[0079] Step 1: The user starts the system through the human-computer interaction module and inputs the structural parameters of the multi-branch pneumatic pipeline system according to the structural parameters of the positive and negative pressure channels of the seed metering device for the current crop. The parameters are then transmitted to the control module via serial communication. The seed metering device is an existing structure.

[0080] Step 2: The control module receives structural parameter information from the human-machine interaction module and, in conjunction with the real-time inlet flow value of the branch pipe equipped with the branch pipe flow sensor, calls the preset branch pipe flow prediction model to prepare for subsequent calculations.

[0081] Step 3: The main pipe pressure sensor monitors the pressure changes at the main pipe inlet in real time and sends the detection data to the control module via the signal bus;

[0082] Step 4: The branch flow sensor measures the real-time inlet flow (Q) of the branch pipe equipped with the branch flow sensor. j, here j takes 1) to monitor and transmit the data synchronously to the control module through the signal bus;

[0083] Step five, the control module integrates the branch pipe flow data in step four and the total pipe gas pressure data in step three, calculates the inlet flow values (Q j , here j takes 2-10) and the inlet flow variation coefficient (CV), and transmits the calculation results to the human-computer interaction module to realize the visual display of the real-time flow of each branch pipe, the inlet flow variation coefficient and the pressure of the total pipe of the pneumatic pipeline system, so as to facilitate the user to monitor the system running state in real time;

[0084] Step six, the control module generates the fan speed adjustment instruction by the incremental PID control algorithm according to the real-time flow data of the branch pipe in step four and the model calculation results in step five, and sends the instruction to the fan control module, with the double regulation and control targets of minimizing the inlet flow variation coefficient and the total pipe pressure fluctuation; the control signal generation process includes:

[0085] (1) Error calculation: the branch pipe flow variation coefficient deviation and the total pipe pressure deviation are weighted and fused to generate a composite error signal e c (k) :

[0086] e c (k) = a e flow (k) + b e pressure (k),

[0087] In the formula, e flow (k) represents the branch pipe flow variation coefficient deviation at the current time, which is the set value minus the measured value; e pressure (k) represents the total pipe pressure deviation at the current time, which is the target value minus the measured value; the weight coefficients a and b are dynamically adjusted according to the system priority (for example, a = 0.7 for flow balance and b = 0.3 for pressure fluctuation suppression).

[0088] (2) PID output: the incremental PID control algorithm is used to calculate the fan speed adjustment amount Au:

[0089]

[0090] In the formula, e c (k) represents the composite error signal deviation at the current time, which is the set value minus the measured value; e c (k-1) represents the composite error signal deviation at the last time, which is the set value minus the measured value; e c (k-2) represents the composite error signal deviation at the last time based on e c (k-1), which is the set value minus the measured value; T d , T i, T are differential time constant, integral time constant and sampling period respectively, the values of P, I, D are dynamically adjusted according to system priority.

[0091] Step seven, the fan control module receives the control signal sent by the control module, dynamically adjusts the running state of the fan, so as to realize the reasonable distribution of the gas pipeline system branch pipe gas flow and the stable control of the total pipe gas pressure.

[0092] The application constructs a simple and efficient monitoring network through the branch pipe flow sensor and the total pipe negative pressure sensor installed in the key position, combines the precise mathematical model embedded in the control module, realizes the rapid prediction and fine regulation and control of the multi-branch pipe flow, thereby replacing the traditional way of laying multiple sensors on the whole pipeline, significantly reducing the production cost and maintenance complexity of the whole machine; At the same time, without affecting the monitoring accuracy and the response speed of the control, the optimization and control requirements of the whole pneumatic seeding system are achieved; The system is suitable for precision cultivation of rice, vegetables and other common crops, has good universality and market prospect.

[0093] The parallel pipeline of the gas supply system provided by the application adopts symmetrical layout and detachable combination structure, the structure parameters of the branch pipe, the main pipe, the total pipe and other core components support rapid replacement and adaptation, can flexibly match the geometric parameters of the seed discharge structure of different types of seeding machines, meet the scale and standardized production application requirements from small test equipment to large and medium-sized agricultural machinery; In view of the problems of long multi-branch pipeline transmission path, slow gas pressure response, fan control delay and frequent adjustment in the traditional gas supply system, the differential negative pressure sensor installed at the end of the total pipe is introduced, the gas pressure fluctuation characteristics at the gas flow outlet are monitored in real time, the control module makes early judgment based on real-time pressure data, and the dynamic adjustment instruction is issued to the control module through the predictive control strategy and the PID control strategy, so that the phenomenon of fan repeated control or speed fluctuation is effectively reduced, and the overall operation stability of the system is improved.

[0094] The application has a high intelligent level, a user can input the structure parameters of the multi-branch pneumatic pipeline through the man-machine interaction module, the control module calls the built-in mathematical model after reading, combines the inlet airflow data collected by the branch pipe flow sensor in real time, and quickly completes the mathematical prediction of the rest of the branch pipe flow and the calculation of the branch pipe flow variation coefficient. Combined with the PID control algorithm, the system can judge the current airflow distribution uniformity according to the branch pipe flow variation coefficient value, and implement adaptive adjustment of the fan speed through the fan control module to realize accurate dynamic control of the seeding air pressure; and the above whole process does not need frequent manual intervention, greatly simplifies the operation process, effectively guarantees the continuous stability of the air pressure environment in the operation process, fundamentally improves the seeding efficiency, seeding uniformity and energy utilization efficiency of the air supply system of the whole machine, reduces the economic and time cost in the operation process, and provides solid technical support for the popularization and application of the air suction type seeding machine in the field operation and plot breeding and other scenes.

[0095] The above embodiments are preferred embodiments of the application, but the embodiments of the application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the application shall be equivalent replacement modes and shall be included in the protection scope of the application.

Claims

1. A method for dynamic airflow distribution and pressure stabilization control in parallel pipelines of a pneumatic seeder, characterized in that: The system includes a signal bus, power bus, control module, human-machine interface module, branch pipe flow sensor, pneumatic pipeline system, fan control module, power module, and main pipe pressure sensor. The pneumatic pipeline system includes a main pipe and multiple parallel branch pipes. There is one branch pipe flow sensor, which collects the inlet flow data of the leftmost branch pipe in real time. The main pipe pressure sensor is responsible for monitoring the inlet negative pressure value of the main pipe in real time. The airflow status of the pipeline is obtained in real time by the branch pipe flow sensor installed on the branch pipe and the main pipe pressure sensor installed on the main pipe. The system predicts the status of each branch pipe in the parallel pipeline through the branch pipe flow prediction model embedded in the control system, and outputs control signals to the fan control module through PID control algorithm and dynamic feedback optimization strategy to dynamically adjust the output power and speed of the fan, thereby realizing the distribution of branch pipe airflow and the optimal control of main pipe negative pressure.

2. The method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 1, characterized in that, Includes the following steps: Step 1: The user starts the system through the human-computer interaction module and inputs the structural parameters of the multi-branch pneumatic pipeline system according to the structural parameters of the positive and negative pressure channels of the seed metering device for the current crop. The input is then transmitted to the control module via serial communication. Step 2: The control module receives structural parameter information from the human-machine interaction module and, in conjunction with the real-time inlet flow value of the branch pipe equipped with the branch pipe flow sensor, calls the preset branch pipe flow prediction model to prepare for subsequent calculations. Step 3: The main pipe pressure sensor monitors the pressure changes at the main pipe inlet in real time and sends the detection data to the control module via the signal bus; Step 4: The branch pipe flow sensor monitors the real-time inlet flow of the branch pipe equipped with the branch pipe flow sensor and transmits the data synchronously to the control module via the signal bus. Step 5: The control module integrates the branch pipe flow data from Step 4 and the main pipe pressure data from Step 3, calculates the inlet flow value and inlet flow variation coefficient of each of the remaining branches based on the built-in branch pipe flow prediction model, and transmits the calculation results to the human-machine interaction module to realize the visualization display of the real-time flow, inlet flow variation coefficient and main pipe pressure information of each branch of the pneumatic pipeline system, so as to facilitate users to monitor the system operation status in real time. Step 6: Based on the real-time flow data of the branch pipe in Step 4 and the model calculation results in Step 5, and with the dual control objectives of minimizing the coefficient of variation of inlet flow and minimizing the pressure fluctuation of the main pipe, the control module generates a fan speed adjustment command through an incremental PID control algorithm and sends it to the fan control module. Step 7: The fan control module receives the control signal from the control module and dynamically adjusts the fan's operating status, thereby achieving reasonable distribution of airflow in each branch pipe of the pneumatic pipeline system and stable control of the main pipe's air pressure.

3. The method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 2, characterized in that: In step five, the branch pipe flow sensor measures the real-time inlet flow rate of the branch pipe as Q1, and the inlet flow rate of the other branch pipes as Q. i The calculation formula is: In the formula, x is a variable factor, f(x) is the function model under that variable factor, and x can be any factor among Q1, d, l, δ, γ, Δ, and D. When x is determined to be a certain factor, the product of the function expressions of the remaining factors forms the constant term λ. At this time, ξ is the error compensation coefficient to improve the calculation accuracy of the formula; Q1: is the real-time inlet flow rate of the leftmost branch pipe, in m³ / s. 3 ·s -1 ; d is the inner diameter of the branch pipe, in mm; l is the length of the branch pipe, in mm; δ is the spacing between the branch pipes, in mm; γ is the inner diameter of the manifold, in mm; Δ is the length of the main pipe, in mm; D is the inner diameter of the main pipe, in mm. The formula for calculating the coefficient of variation of inlet flow is: In the formula, n is the number of branches; j is the serial number of each branch, arranged from left to right, ranging from 1 to 10; Q j The inlet flow rate of each branch pipe, in m³ / s. 3 ·s -1 Q m This is the average flow rate at the inlet of each branch pipe, in m³. 3 ·s -1 .

4. The method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 2, characterized in that, In step six, the fan speed regulation algorithm design adopts the standard incremental PID algorithm, and the control signal generation process includes: (1) Error Calculation: The deviation of the branch pipe flow variation coefficient and the deviation of the main pipe pressure are weighted and fused to generate a composite error signal e. c (k): e c (k)=α·e flow (k)+β·e pressure (k), In the formula, e flow (k) represents the deviation of the branch flow variation coefficient at the current moment, which is the set value minus the measured value; e pressure (k) represents the current pressure deviation of the main pipe, which is the target value minus the measured value; the weighting coefficients α and β are dynamically adjusted according to the system priority. (2) PID Output: The incremental PID control algorithm is used to calculate the fan speed adjustment Δu: In the formula, e c (k) represents the current composite error signal deviation, which is the difference between the set value and the measured value; e c (k-1) represents the composite error signal deviation at the previous moment, which is the difference between the set value and the measured value; e c (k-2) represents the value in e c The deviation of the composite error signal from the previous time step based on time (k-1) is the set value minus the measured value; T d T i T and I are the differential time constant, integral time constant, and sampling period, respectively. The values ​​of P, I, and D are dynamically adjusted according to the system priority.

5. The method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 1, characterized in that: The signal bus is used for data communication and control command transmission; the power bus is used for stable DC power transmission; the control module is used for system information reception, data processing, and control command transmission; the human-machine interface module is used to realize information interaction between the user and the control module; the pneumatic pipeline system is used for airflow transmission and distribution, and is the core actuator for air pressure regulation; the fan control module is responsible for receiving control commands issued by the control module and regulating the fan's operating status in real time; the power module is used to provide stable power output and also has overvoltage and overcurrent protection functions; the main pipe air pressure sensor transmits data to the control module via wired connection, serving as reference data for the control module to determine whether the fan needs further regulation.

6. The method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 1, characterized in that: The pneumatic pipeline system includes a branch tee (601), a branch pipe (602), a manifold connection pipe (603), a main tee (604), a main pipe (605), a branch inlet flow measurement pipe (606), a manifold end cap (607), a manifold end connection pipe (608), a negative pressure measurement pipe (609), a corrugated pipe (610), a clamp (611), a fan (612), a Pitot tube (613), and a rubber hose (614); The pneumatic pipeline system consists of three main components: a main pipe (605), manifolds, and branch pipes (602). The manifold includes a branch tee pipe (601), a manifold connecting pipe (603), a manifold end cap (607), and a manifold end connecting pipe (608). The manifold connecting pipe is used to connect adjacent branch tee pipes. The manifold end connecting pipe is located on the outside of the branch tee pipes at both ends and is sealed by the manifold end cap. The branch pipe (602) is connected to the channel of the branch tee pipe (601) perpendicular to the direction of the manifold through an equidistant parallel layout pattern; The main pipe (605) is located in the middle of the manifold and is connected to the manifold through the main pipe tee (604). It is connected to the inlet channel of the fan (612) through the series connection of the negative pressure measuring pipe (609) and the corrugated pipe (610). The corrugated pipe (610) is fixed to the outlet of the negative pressure measuring pipe (609) and the inlet of the fan (612) by clamps (611). The branch inlet flow measurement tube is set on the leftmost branch pipe, and the branch flow sensor is installed on the branch inlet flow measurement tube; The negative pressure measuring tube, pitot tube, rubber hose, and main air pressure sensor are connected in sequence.

7. A method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 6, characterized in that: The branch pipe flow sensor uses the thermal model induction principle to obtain the real-time inlet flow of the branch pipe. The branch pipe inlet flow measurement tube is vertically arranged at the airflow inlet of the branch pipe and transmits the data to the control module via a wired method. The main pipe pressure sensor uses the differential pressure principle to measure the real-time negative pressure at the main pipe outlet and transmits the data to the control module via a wired connection.

8. A method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 1, characterized in that: The signal bus uses the RS485 communication protocol to complete data communication; the power bus is configured according to the system power; the power module uses a battery pack, equipped with overvoltage, overcurrent, and short-circuit protection circuits and real-time power status display function, to provide continuous and reliable DC power to the control module, human-machine interaction module, branch flow sensor, fan control module and main pipe pressure sensor.

9. A method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 1, characterized in that: The control module uses an STM32 microcontroller as its core processor, which is responsible for receiving and processing various signal inputs from the system, as well as the pipeline airflow information collected by the branch flow sensor and the main pipe pressure sensor. The control module also processes the structural parameters of the multi-branch pneumatic pipeline system input by the human-machine interface module.

10. A method for dynamic distribution and pressure regulation of airflow in parallel pipelines of a pneumatic seeder according to claim 1, characterized in that: The human-computer interaction module uses a touch screen or tablet to transmit string data to the control module via a wired connection, and displays the system operating parameters to the user intuitively through a serial port screen.

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