油菜播种机除尘式播量监测系统设计与试验OACSTPCD

[Objective]The pneumatic rapeseed seeder easily inhales the dust generated during live broadcast operations into the seeding pipe,and then releases it along with the rapeseed.Consequently,when monitoring the rapeseed flow,dust interference can affect the flow,detec-tion sensitivity and accuracy.This research aims to develop a dust removal rapeseed seeding rate monitoring system suitable for air-as-sisted pneumatic rapeseed seeders to improve the transparency and intelligence of the sowing process. [Methods]The monitoring system comprised a dust removal rapeseed seed flow detection device and a sowing monitoring terminal,which could be adjusted for different seeders widths by altering the number of detection devices.The rapeseed stream sensing struc-ture operated on the principle of photoelectric induction.A delicate light layer was generated using an LED light source and a narrow slit structure.The convex lens condenses the light and directed it onto the sensing area of the silicon photovoltaic cell.When the rape-seed seeds pass through the sensing light layer,the silicon photovoltaic cell produced a voltage change signal.The signal converts it into a pulse signal that can be recognized by the microcontroller.A dust removal mechanism was designed by analyzing dust sources in the seeding system during normal field operation of the air-assisted rapeseed seeding machine and understanding the impact mecha-nism of the dust detection device on the accuracy of rapeseed flow monitoring.This mechanism employed a transparent plate to pro-tect the photoelectric induction device in a relatively enclosed space and used a stepper motor screw mechanism to generate friction between the transparent plate and the dust removal cloth for effective dust removal.The appropriate size of the dust shield was deter-mined by comparing its movement stroke with other structural dimensions of the detection device.The relationship between the sili-con photocells voltage and detection accuracy was established through experiments at seeding frequencies of 10‒40 Hz.To ensure that the real-time detection accuracy was not less than 90%,the dust removal control threshold was set at 82%of the initial voltage value.In order to prevent congestion and data loss during data transmission and improve the scalability and compatibility of the monitoring system,data transmission between the detection device and the monitoring terminal was implemented based on the CAN2.0A commu-nication protocol.The structural framework and monitoring terminal functions of the rapeseed sowing monitoring system were out-lined.Software functions of the detection device were designed to meet the dust removal,communication,and rapeseed flow detection needs.The program execution process of the detection device was explained.In order to provide data support for the dust flow rate that should be controlled at various seeding frequencies during the bench test,experiments were conducted in the field to obtain theo-retical data. [Results and Discussions]The comparison bench test of the detection device indicates that with the average seeding frequency ranging from 12.4 to 36.3 Hz and the average dust flow rate ranging from 252 to 386 mg/s,the detection accuracy after two dust removal cy-cles without a dustproof and dust removal detection device was not higher than 80.2%.The dust detection device with dust removal got an accuracy rate of not less than 90.2%,and the average detection accuracy rate within a single dust removal cycle was not less than 93.6%.The seeding amount monitoring bench test showed that when the average seeding frequency was no higher than 37.6 Hz,the seeding rate monitoring accuracy was not less than 92.2%.Furthermore,the field sowing experiment results demonstrated that at a normal operating speed(2.8‒4.6 km/h)of the rapeseed direct seeder,with a field sowing frequency of 14.8‒31.1 Hz,the accuracy of sowing quantity monitoring was not less than 93.1%. [Conclusions]The rapeseed sowing quality monitoring system provides effective support for precise detection even when operating in dusty conditions with the pneumatic rapeseed direct seeder.In the future,by integrating positioning data,sowing information,and fer-tilization monitoring data through CAN bus technology,a comprehensive field sowing and fertilization status map can be created to further enhance the system's capabilities.