阅读说明：本技术 气力式排种装置多路动态负压监测系统及方法 (Multi-path dynamic negative pressure monitoring system and method for pneumatic seed metering device ) 是由 陈永新 谢瑞 蒋乐 张甜 韩建锋 钟继宇 李兆东 张顺 于 2021-06-05 设计创作，主要内容包括：本发明涉及气力式播种机技术领域,具体公开了一种气力式排种装置多路动态负压监测系统及方法；包括多个并排设置的排种器、支路正负压气管、干路正负压气管、以及负压风机,支路负压气管和干路负压气管上均设置有压力传感器,干路负压气管上设置有电动阀门,压力传感器均共同连接数据采集卡,数据采集卡连接上位机；本发明实现了对气力式排种装置整体干路及各个支路动态负压值的监测,包括动态负压数据的实时采集、读取、分离、显示和保存,为排种装置排种性能的试验研究、排种装置智能检测及可靠性分析等提供了依据,弥补了现有关于排种器中气力系统的多路动态负压监测的不足,为实现播种机的精准排料、稳定运行奠定了基础。(The invention relates to the technical field of pneumatic seeding machines, and particularly discloses a multi-path dynamic negative pressure monitoring system and a multi-path dynamic negative pressure monitoring method for a pneumatic seed metering device; the system comprises a plurality of seed sowing devices, branch positive and negative pressure air pipes, a trunk positive and negative pressure air pipe and a negative pressure fan which are arranged side by side, wherein pressure sensors are arranged on the branch negative pressure air pipe and the trunk negative pressure air pipe respectively, an electric valve is arranged on the trunk negative pressure air pipe, the pressure sensors are connected with a data acquisition card together, and the data acquisition card is connected with an upper computer; the invention realizes the monitoring of the dynamic negative pressure values of the whole trunk and each branch of the pneumatic seed sowing device, including the real-time acquisition, reading, separation, display and storage of dynamic negative pressure data, provides a basis for the experimental research of the seed sowing device on the seed sowing performance, the intelligent detection and reliability analysis of the seed sowing device and the like, makes up the defects of the prior multi-path dynamic negative pressure monitoring of the pneumatic system in the seed sowing device, and lays a foundation for realizing the accurate discharging and stable operation of the seeder.)

1. The utility model provides a pneumatic formula seed metering device multichannel developments negative pressure monitoring system, includes a plurality of seed metering ware and the fan that sets up side by side, every all be connected with branch road just, negative pressure trachea on the seed metering ware, it is a plurality of branch road just-pressing trachea assembles a bit and is connected with trunk road just-pressing trachea, it is a plurality of branch road negative pressure trachea assembles a bit and is connected with trunk road negative pressure trachea, trunk road just-pressing trachea and trunk road negative pressure trachea are connected with the end of giving vent to anger, the end of bleeding of fan respectively, its characterized in that, all be provided with pressure sensor on branch road negative pressure trachea and the trunk road negative pressure trachea, be provided with electric valve on the trunk road negative pressure trachea, and electric valve sets up the upper reaches of the pressure sensor on the trunk road negative pressure trachea, every the equal common electric connection of pressure sensor has data acquisition card, data acquisition card electric connection has the host computer.

2. The multi-channel dynamic negative pressure monitoring system for the pneumatic seed metering device according to claim 1, further comprising a rack, wherein a plurality of seed metering devices are fixedly arranged at the upper end of the rack side by side.

3. A multi-channel dynamic negative pressure monitoring method by using the multi-channel dynamic negative pressure monitoring system of the pneumatic seed metering device of claim 1 or 2, which is characterized by comprising the following steps:

1) dynamic negative pressure data acquisition

Setting a collection channel: setting relevant parameters on a LabVIEW software interface according to a channel connected with a pressure sensor and a data acquisition card;

storage of sensor signals: under the state that the seeding shaft rotates, the pressure sensor collects dynamic negative pressure in the dry branch negative pressure air pipe and the branch negative pressure air pipe, converts the dynamic negative pressure into an analog voltage signal, and transmits the analog voltage signal to the data acquisition card for storage;

2) dynamic negative pressure data reading and conversion

Analog voltage signals in the data acquisition card are converted into actual dynamic negative pressure data according to a linear relation between physical quantities by utilizing a reading function in LabVIEW software;

3) dynamic negative pressure data separation

The converted two-dimensional array dynamic negative pressure data utilizes an index array function in LabVIEW software to carry out data separation on the data of the dynamic negative pressure of the trunk and the branch;

4) analysis of dynamic negative pressure data of dry and branch circuits

Analyzing main road data: judging whether the dynamic negative pressure data of the trunk line is in an ideal value range, if not, controlling the electric valve to automatically adjust the opening of the valve to ensure that the dynamic negative pressure data of the trunk line is in the ideal value range;

analyzing branch data: on the premise that the dynamic negative pressure data of the trunk line is in an ideal value range, if the dynamic negative pressure value of a certain branch line is close to 0, the air leakage phenomenon of the corresponding branch line air pipe is shown, at the moment, the alarm of the corresponding branch line is sent out, and the system stops collecting and reminds an operator to check the fault;

5) dynamic negative pressure data preservation

And after the real-time monitoring is finished, storing the dynamic negative pressure data of the trunk and branch circuits according to a specified storage path.

4. The multi-channel dynamic negative pressure monitoring method according to claim 3, wherein the analysis of the dynamic negative pressure data of the trunk and branch circuits in step 4 is performed every 3 min.

5. The multi-channel dynamic negative pressure monitoring method according to claim 3, wherein the ideal value range in the step 4 is a dynamic negative pressure value range of a main channel in a state of stable seed metering performance of a seed metering device.

6. The multi-channel dynamic negative pressure monitoring method according to claim 3, wherein the specific steps of automatically adjusting the opening degree of the electric valve in the step 4 are as follows: when the dynamic negative pressure data of the trunk line is larger than the ideal value range, the electric valve automatically adjusts to reduce the opening; when the dynamic negative pressure data of the trunk line is smaller than the ideal value range, the electric valve automatically adjusts to increase the opening.

7. The multi-channel dynamic negative pressure monitoring method according to claim 3, wherein the step 4 of the dry and branch dynamic negative pressure data further comprises displaying a waveform diagram of the dry and branch dynamic negative pressure data on a LabVIEW software interface.

8. The multi-channel dynamic negative pressure monitoring method according to claim 3, wherein the corresponding branch in the step 4 is alarmed through a set fault lamp.

Technical Field

The invention relates to the technical field of pneumatic seeding, and particularly discloses a multi-path dynamic negative pressure monitoring system and method for a pneumatic seed metering device.

Background

A pneumatic seed discharging device is a seeder which sucks seeds by negative pressure to realize precision seeding. The seed sowing device mainly comprises an air suction type seed sowing device, an air blowing type seed sowing device, an air pressure type seed sowing device, a positive pressure and negative pressure combined type seed sowing device and the like, and the key components of the seed sowing device are pneumatic type precise seed sowing devices. At present, researchers at home and abroad research the pneumatic seeding technology mainly focuses on the aspects of structural design and optimization of a seeding unit, mechanism research and improvement of seed filling performance, simulation of the seeding performance of the seeding unit, bench test research and the like, the monitoring and control research on air pressure in a pneumatic system is relatively less, and the pneumatic system in the pneumatic seeder is also an important factor for realizing accurate quantification and stable operation of a seeding device.

At present, the pneumatic system in the seeding unit is mainly researched by julian celebration and the like in the pneumatic seeding system performance research of the rape precision combined direct seeding machine at home, the pneumatic system pressure value read by the U-shaped pressure gauge is used as the working negative pressure of the system under the working condition, but the U-shaped pressure gauge can only read a certain transient value and cannot be used as the actual working negative pressure of the system under the working condition. In addition, when researching the mechanism of air flow in the pneumatic conveying type seeder pipe, the Liuliu crystal and the like adopt a wind pressure meter to measure static negative pressure of a seeding shaft of the seeding device under a non-rotating working condition to replace actual working negative pressure, the actual working negative pressure of a system in actual working is dynamic negative pressure under a rotating working condition of the seeding shaft, and meanwhile, the actual dynamic negative pressure of the pneumatic seeding device in multi-row parallel working is greatly fluctuated, so that the effects of accurately reading and monitoring multi-path dynamic negative pressure in a pneumatic system of the seeding device in real time cannot be achieved.

Also, as disclosed in the invention patent with application number 2015100265558, a feed-back adjusting device and a feed-back adjusting method thereof for seed metering of an air-suction seed metering device are disclosed, wherein the device comprises a shell connected with the air-suction seed metering device; the camera is used for acquiring the seed condition on a seed discharging disc of the air-suction type seed discharging device and acquiring the information of the image of the change of the seed quantity on line; the light source is used for providing required illumination for the camera; the single chip microcomputer is used for processing the original data collected by the camera, including image enhancement, segmentation and target feature extraction; the proportional electromagnetic valve is arranged on a pipeline connected with the air-suction type seed sowing device by the fan, receives information fed back by the singlechip and adjusts the size of a flow switch of the proportional electromagnetic valve in real time; the camera, the light source and the single chip microcomputer are arranged in the shell respectively, the camera faces to a seed discharging disc suction port of the air suction type seed discharging device, shooting is carried out in a seed carrying process, and the seed condition on the seed discharging disc is collected in real time. Although the invention realizes the implementation monitoring of the seed metering situation by the method of camera capture and picture analysis and can provide the feedback adjustment of negative pressure, the seed metering units in the pneumatic seeder are generally arranged in parallel, and the application of the device on the pneumatic seed metering device can simultaneously monitor multiple paths in the seed metering process by arranging the camera and the light source on each seed metering unit, so that the manufacturing cost of the whole pneumatic seeder is higher and the practicability is lower. Aiming at the defects of the research on a pneumatic system in the existing seed metering device and the poor practicability of the existing seed metering feedback adjusting device of the air-suction type seed metering device in the practical application process, the multipath dynamic negative pressure monitoring system and the method of the pneumatic seed metering device based on LabVIEW application are provided to solve the defects of the prior art.

Disclosure of Invention

Technical problem to be solved

Aiming at the problems that the conventional multi-row parallel pneumatic seed metering device is difficult to accurately read and monitor in real time due to large dynamic negative pressure fluctuation, a multi-channel dynamic negative pressure monitoring system of the seed metering device based on LabVIEW is designed by applying a LabVIEW virtual instrument technology, and the real-time monitoring of dynamic negative pressures of a trunk and a branch is realized.

(II) technical scheme

The invention is realized by the following technical scheme:

the utility model provides a pneumatic formula seed metering device multichannel developments negative pressure monitoring system, includes a plurality of seed metering ware and the fan that sets up side by side, every all be connected with branch road on the seed metering ware just, negative pressure trachea, it is a plurality of branch road positive pressure trachea assembles and is connected with trunk road positive pressure trachea a bit, and is a plurality of branch road negative pressure trachea assembles and is connected with trunk road negative pressure trachea a bit, trunk road positive pressure trachea and trunk road negative pressure trachea are connected with the end of giving vent to anger, the end of bleeding of fan respectively, all be provided with pressure sensor on branch road negative pressure trachea and the trunk road negative pressure trachea, be provided with electric valve on the trunk road negative pressure trachea, and electric valve sets up the upper reaches of the pressure sensor on the trunk road negative pressure trachea, every the equal common electric connection of pressure sensor has data acquisition card, data acquisition card electric connection has the host computer.

As a further arrangement of the scheme, the seeding device further comprises a rack, and a plurality of seeding devices are fixedly arranged at the upper end of the rack side by side.

A multi-channel dynamic negative pressure monitoring method using the multi-channel dynamic negative pressure monitoring system of the pneumatic seed metering device comprises the following steps:

1) dynamic negative pressure data acquisition

Setting a collection channel: setting relevant parameters on a LabVIEW software interface according to a channel connected with a pressure sensor and a data acquisition card;

storage of sensor signals: under the state that the seeding shaft rotates, the pressure sensor collects dynamic negative pressure in the dry branch negative pressure air pipe and the branch negative pressure air pipe, converts the dynamic negative pressure into an analog voltage signal, and transmits the analog voltage signal to the data acquisition card for storage;

2) dynamic negative pressure data reading and conversion

Analog voltage signals in the data acquisition card are converted into actual dynamic negative pressure data according to a linear relation between physical quantities by utilizing a reading function in LabVIEW software;

3) dynamic negative pressure data separation

The converted two-dimensional array dynamic negative pressure data utilizes an index array function in LabVIEW software to carry out data separation on the data of the dynamic negative pressure of the trunk and the branch;

4) analysis of dynamic negative pressure data of dry and branch circuits

Analyzing main road data: judging whether the dynamic negative pressure data of the trunk line is in an ideal value range, if not, controlling the electric valve to automatically adjust the opening of the valve to ensure that the dynamic negative pressure data of the trunk line is in the ideal value range;

analyzing branch data: on the premise that the dynamic negative pressure data of the trunk line is in an ideal value range, if the dynamic negative pressure value of a certain branch line is close to 0, the air leakage phenomenon of the corresponding branch line air pipe is shown, at the moment, the alarm of the corresponding branch line is sent out, and the system stops collecting and reminds an operator to check the fault;

5) dynamic negative pressure data preservation

And after the real-time monitoring is finished, storing the dynamic negative pressure data of the trunk and branch circuits according to a specified storage path.

As a further configuration of the above scheme, the analysis of the dynamic negative pressure data of the dry branch and the branch in step 4 is performed every 3 min.

As a further arrangement of the above scheme, the ideal value range in step 4 is a dynamic negative pressure value range of the main line in a state of stable seed metering performance of the seed metering device.

As a further arrangement of the above scheme, the specific steps of automatically adjusting the opening degree of the electric valve in the step 4 are as follows: when the dynamic negative pressure data of the trunk line is larger than the ideal value range, the electric valve automatically adjusts to reduce the opening; when the dynamic negative pressure data of the trunk line is smaller than the ideal value range, the electric valve automatically adjusts to increase the opening.

As a further configuration of the above scheme, the dynamic negative pressure data of the trunk and branch in step 4 further includes a waveform diagram for displaying the dynamic negative pressure data of the trunk and branch on a LabVIEW software interface.

As a further arrangement of the above scheme, the corresponding branch in step 4 alarms through a set fault lamp.

(III) the beneficial effects are as follows:

1) the invention discloses a multi-channel dynamic negative pressure monitoring system of a pneumatic seed metering device based on LabVIEW application, which realizes real-time monitoring of dynamic negative pressure values of an integral trunk of the pneumatic seed metering device and each seed metering device branch.

2) Compared with the existing seed metering feedback adjusting device and feedback adjusting method of the air-suction seed metering device, the seed metering feedback adjusting device and feedback adjusting method of the air-suction seed metering device have the advantages that the pressure sensors are only needed to be arranged in the branch negative pressure air pipes and the trunk negative pressure air pipes, then, LabVIEW software is utilized to carry out real-time monitoring and feedback adjustment on the running state in the air-suction seed metering device, a plurality of cameras are not needed to capture and analyze the running condition of each seed metering device, when the system is applied to the seed metering device, the manufacturing cost of the seed metering device is effectively reduced on the premise that the precise discharging and stable running of the seed metering device are ensured, and the practicability is higher than that of the prior art.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic perspective view of a detection system according to the present disclosure;

fig. 2 is a schematic flow chart of a multi-channel dynamic negative pressure monitoring method disclosed by the invention.

The system comprises a rack 1, a seed sowing device 2, a branch 3 negative pressure air pipe, a branch 4 positive pressure air pipe, a trunk 5 negative pressure air pipe, a trunk 6 positive pressure air pipe, a blower 7, a pressure sensor 8, an electric valve 9, a data acquisition module 10 and an upper computer 11.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", and,

The terms "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like, refer to an orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are used primarily to better describe the invention and its embodiments and are not intended to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation.

Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meanings of these terms in the present invention can be understood by those skilled in the art as appropriate.

Furthermore, the terms "mounted," "disposed," "provided," "connected," and "sleeved" are to be construed broadly. For example, it may be a fixed connection, a removable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The following will explain the multi-channel dynamic negative pressure monitoring system of the pneumatic seeding device based on LabVIEW in the invention with reference to the attached figure 1.

The invention discloses a multi-channel dynamic negative pressure monitoring system of a pneumatic seed metering device based on LabVIEW application, which comprises a rack 1 and seed metering devices 2, wherein the seed metering devices 2 are arranged at the upper end of the rack 1 side by side, and a seed receiving cup is also arranged below each seed metering device. The seed sowing device 2 is a pneumatic seed sowing device, the pneumatic seed sowing device is in the prior art, and detailed description is omitted here. A branch negative pressure air pipe 3 and a branch positive pressure air pipe 4 are respectively connected on each seed sowing device, a plurality of branch negative pressure air pipes 3 are converged to one point and are connected to a trunk negative pressure air pipe 5, and a plurality of branch positive pressure air pipes 4 are converged to one point and are connected to a trunk positive pressure air pipe 6. A plurality of fault lamps (not shown) are provided as alarm devices, and each fault lamp corresponds to each main negative pressure air pipe 5. The lower end of the frame 1 is provided with a negative pressure fan 7, the vacuum degree range of the negative pressure fan 7 is-22-0 KPa, the trunk negative pressure air pipe 5 is connected with the air exhaust end of the negative pressure fan 7, and the trunk positive pressure air pipe 6 is connected with the air outlet end of the negative pressure fan 7. The monitoring system is characterized in that each branch negative pressure air pipe 3 and each trunk negative pressure air pipe 6 are respectively provided with a pressure sensor 8, the range of the pressure sensor is-30 KPa-0 KPa, the overload pressure is 150% FS, the response time is 90% FS, and the output is 0-5V analog voltage signals. Meanwhile, an electric valve 9 is arranged on the main-line negative-pressure air pipe 6, and the electric valve 9 is arranged at the upstream of the pressure sensor on the main-line negative-pressure air pipe 5 (namely, on the main-line negative-pressure air pipe 5 close to the negative-pressure fan 7). The valve control module adopts an NI-9263 type voltage output module and an FRSQT11F-16P type electric ball valve (the position accuracy is +/-1%), the valve opening is controlled through a voltage signal to control the actual negative pressure, and the opening of the valve is controlled by inputting a 0-10V voltage signal to correspond to 0-100%.

In addition, the monitoring system also comprises a data acquisition module 10 and an upper computer 11, wherein the data acquisition module 10 adopts an NI-9205 type data acquisition card, the data acquisition module is provided with 32 single-ended analog input channels and 16 differential analog input channels, the acquired voltage range is +/-10V, a voltage signal output by the pressure sensor can be directly acquired by the acquisition card, the sampling rate is 250KS/s, and the requirement of the sampling rate of the sensor can be met. The connection between the pressure sensors 8 on the branch and the trunk and the data acquisition card adopts a differential wiring mode, and the wiring mode can enable the acquired data to be more accurate. And finally, the data acquisition card 10 is electrically connected with an upper computer 11 (namely a computer terminal) through a data line, and the multi-path parallel dynamic negative pressure in the whole seed metering device is monitored, analyzed and controlled through LabVIEW software in a computer.

In summary, the monitoring system takes the pressure sensor as a measuring element, and the NI-9205 type data acquisition card as a data acquisition module, and acquires signals output by the pressure sensor and has the functions of pressure value conversion, real-time display, analysis, storage, fault alarm and the like in LabVIEW software of an upper computer.

In addition, the invention also discloses a monitoring method based on the multi-channel dynamic negative pressure monitoring system of the pneumatic seed metering device, which refers to the attached figure 2 and comprises the following operation steps:

step one, acquiring dynamic negative pressure data

Setting a collection channel: setting parameters such as a collection channel, a sampling rate, a collection number, a sampling mode, a wiring mode and the like on a front panel interface of LabVIEW software according to a channel connected with a data collection card by a pressure sensor;

storage of sensor signals: under the state that the seeding shaft rotates, the pressure sensor collects dynamic negative pressure in the dry and branch negative pressure air pipes, converts the dynamic negative pressure into 0-5V analog voltage signals, and transmits the analog voltage signals to the data acquisition card for storage.

Step two, reading and converting dynamic negative pressure data

The data in the data acquisition card is an analog voltage signal of 0-5V, a DAQmx reading function in LabVIEW software is utilized to read out the voltage signal in the data acquisition card, and the voltage signal of the sensor and the pressure signal are in linear correspondence, so that the voltage signal is converted into the actually required dynamic negative pressure data according to the linear relationship between physical quantities.

Step three, separating dynamic negative pressure data

The converted dynamic negative pressure data is a two-dimensional array, and the data of the dynamic negative pressure of the trunk and branch are separated by using an index array function in LabVIEW software;

step four, analyzing the dynamic negative pressure data of the trunk and branch lines

Analyzing main road data: firstly, judging whether data of dynamic negative pressure of a main path is in an ideal value range, wherein the ideal value range is a dynamic negative pressure value in a stable seeding performance state obtained according to experimental research, specifically, calculating a corresponding rotating speed of a seeding shaft in a seeding apparatus according to an advancing speed of the seeding machine, and then matching the corresponding valve opening according to the rotating speed of the seeding shaft to obtain the dynamic negative pressure value in the stable seeding performance. When the dynamic negative pressure value of the trunk line is larger or smaller than the ideal value range under a certain valve opening degree, the electric valve can automatically adjust to reduce or increase the valve opening degree, the dynamic negative pressure value of the trunk line is ensured to be in the ideal range, and at the moment, the front panel interface can display the waveform of the trunk line in real time;

analyzing branch data: under the condition that the dynamic negative pressure data of the trunk circuit is normal (namely the dynamic negative pressure data of the trunk circuit is within an ideal value range), the dynamic negative pressure data of each branch circuit is normal, and the waveform of each branch circuit is displayed on the front panel interface. When the dynamic negative pressure value of a certain branch is close to 0, the air leakage phenomenon of the corresponding branch pipe is indicated, the fault lamp of the corresponding branch is normally on to give an alarm, and the system stops collecting and reminds an operator to check the fault;

step five: dynamic negative pressure data preservation

After the real-time monitoring is finished, the storage button is clicked on the front panel, the dynamic negative pressure data of the trunk and branch lines are stored in the excel table, and the designated storage path can be selected to store the data table. In specific setting, the analysis of the dynamic negative pressure data of the trunk and branch lines is to calculate the mean value, the maximum and minimum values, the standard deviation and the like of the data every 3 minutes, store the acquired data into an Excel table and then store the data.

In order to determine the reliability of the monitoring system, the invention adopts a comparative analysis method, and takes the negative pressure value measured by an SG-312 type air quantity and pressure meter as a comparison standard. In the test, 5 gradients of-1.0, -1.5, -2.0, -2.5 and-3.0 kPa of static negative pressure under the condition that the seeding shaft does not rotate are selected as the negative pressure level, and the dynamic and static negative pressure values measured by the air pressure meter and collected by the sensor under the corresponding negative pressure level are respectively recorded. The measuring data of the dynamic negative pressure and the static negative pressure of the wind pressure meter adopt a camera shooting method, the rotating speed of the seeding shaft is set to be 30r/min when the dynamic negative pressure is measured, the average value of the data within 1min is taken as the data of each group of tests, each group of tests are repeated three times, and the relative error between the pressure sensor and the data of the dynamic negative pressure and the static negative pressure of the wind pressure meter is calculated to obtain the result shown in the table 1.

TABLE 1

Wherein, the above relative error = (wind pressure meter measurement data-sensor collection data)/wind pressure meter measurement data × 100%.

The deviation between the dynamic and static negative pressure values of the pneumatic seeding device main circuit measured by the monitoring system and the wind pressure value measured by the wind pressure meter is not more than 4 percent, thereby achieving the effects of accurately reading the multi-path parallel dynamic negative pressure in the pneumatic system of the seeding device and monitoring in real time.

The embodiment of the specific application research of the multi-path dynamic negative pressure monitoring system disclosed by the invention on the influence of the uniform stability of the dynamic negative pressure among all branches in the rapeseed seeding device, the dynamic negative pressure of a main path and the rotating speed on the seeding performance is as follows:

example 1

In order to determine the distribution uniformity and fluctuation stability of the dynamic negative pressure among the branches, 5 gradients of-1.0, -2.0, -3.0, -4.0 and-5.0 kPa are selected, the rotating speed of the seeding shaft is set to be 30r/min, the dynamic negative pressure value of each branch within 3min is collected, and the mean value, standard deviation and the dynamic negative pressure consistency variation coefficient are calculated to obtain the results shown in the table 2.

TABLE 2

Wherein, the negative pressure uniformity variation coefficient calculation formula is as follows:

in the formulaThe standard deviation of dynamic negative pressure fluctuation of each branch is obtained; s is the variation coefficient of the uniformity of the branch negative pressure; t is time (t = 180);a certain branch dynamic negative pressure value is the ith second;the dynamic negative pressure average value of a certain branch in the t time period;dynamic negative pressure values of each branch circuit are obtained;the average value of the dynamic negative pressure of each branch is shown.

From table 2, it can be derived: the uniform and consistent variation coefficient of the dynamic negative pressure among the branches is in a descending trend along with the increase of the dynamic negative pressure and is not more than 2.5%, but the fluctuation range of the dynamic negative pressure of each branch is in an ascending trend along with the increase of the dynamic negative pressure. The analysis shows that the dynamic negative pressure distribution uniformity among the branches is better, the dynamic negative pressure fluctuation stability of the branches is gradually reduced, and the single pneumatic seed sowing devices adopt the arrangement and combination parallel arrangement to ensure the dynamic negative pressure consistency of the seed sowing devices in each row when in work.

Example 2

In order to explore the influence rule of the dynamic negative pressure of the trunk line and the rotating speed of the seed shaft on the seed discharging performance of the seed discharging device, the lowest dynamic negative pressure of the trunk line required when the seed discharging performance of the seed discharging device is stable under the conditions of different rotating speeds of the seed discharging shaft is determined, and the influence test of the dynamic negative pressure of the trunk line and the rotating speed on the seed discharging performance is carried out. The dynamic negative pressure of the main line is controlled by the opening of the electric valve, the opening of the electric valve is controlled by voltage, and the voltage of 0-10V linearly corresponds to the opening of the valve of 0-100%.

The test takes the rotation speed and voltage (valve opening) of the seeding shaft as test factors, takes the consistency variation coefficient of each row of discharge capacity and the total seeding quantity as evaluation indexes, selects 5 gradients of which the voltage values are 1.5, 2.0, 2.5, 3.0 and 3.5V and 5 gradients of which the rotation speed of the seeding shaft is 20, 30, 40, 50 and 60r/min, and carries out full factor test. Recording dynamic negative pressure of the seeding device under the conditions of different valve openings and the rotational speed of the seeding shaft, wherein the recording time is 3min, taking the average value of data within 3min, repeating each group of tests for 3 times, calculating the consistency variation coefficient of average total seeding quantity and each row of discharge capacity by using a weighing method, and the table 3 shows the dynamic negative pressure and the seeding performance index value under different valve openings when the rotational speed of the seeding shaft is 30 r/min.

TABLE 3

Wherein the content of the first and second substances,the discharge capacity consistency coefficient of variation of each row is calculated according to the related indexes of the GB/T9478-2005 grain drill test method as follows:

in the formulaThe average total seed metering amount; m1, M2 and M3 are the total mass of rape seeds discharged by the N seed guiding tubes in the test for the second time respectively; CV is a variation coefficient of consistency of the discharge capacity of each row; n is the number of seed guiding pipes (N = 8);discharging the average value g of the rape seed quality for the N seed guide pipes;and discharging the quality of the rape seeds for the ith seed guide pipe.

From table 3, it can be seen that: with the increase of the opening degree of the valve, the dynamic negative pressure of the pneumatic seed metering device is in an increasing trend, the average total seed metering quantity is in a stable state after increasing, the consistency variation coefficient of each row discharge capacity is reduced firstly and then stabilized below 4 percent, and the analysis shows that the influence of the excessively low negative pressure on the seed metering performance of the multi-row parallel pneumatic seed metering device is obvious, the seed metering performance of the seed metering device is not obviously improved due to the excessively high negative pressure, the load of a fan is increased due to the excessively high negative pressure, and the fluctuation trend of the dynamic negative pressure of the single pneumatic seed metering device is increased, so that the seed metering device is unstable in work. Meanwhile, when the rotation speed of the seeding shaft is 30r/min, the minimum trunk dynamic negative pressure required by the seeding performance of the seeding device to reach a stable state is 2.635kPa (the valve opening is 26.8%), so that the minimum trunk dynamic negative pressure or the valve opening corresponding to different rotation speeds of the seeding shaft can be obtained according to the advancing speed of a tractor in the actual seeding process.

From the specific application of the embodiments 1 and 2 to the multi-channel dynamic negative pressure monitoring system for the pneumatic seeding device based on LabVIEW research disclosed by the invention, the multi-channel dynamic negative pressure monitoring system and the multi-channel dynamic negative pressure monitoring method disclosed by the invention provide a basis for the test research of the seeding performance of the seeding device, the intelligent detection and reliability analysis of the seeding device, and the reduction of the power consumption and the fan load of the tractor, and lay a foundation for realizing the accurate discharging and stable operation of the seeder.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.