Design And Experiment Of Seed Flow Detection System Of Rapeseed Disturbance Pneumatic Metering Device

For the problem of detection accuracy and long response time,this paper presents a combination of optical fiber induction and wireless WIFI transmission,designs a rapeseed seed flow detection system based on the embedded development board,realizes the rapeseed seed flow real-time detection and data transmission function,test,and the main research conclusions are as follows:(1)Using the theory of particle kinematics to analyze the falling characteristics of rapeseed seeds in the seed guide tube,the theoretical fastest falling time of the seeds in the seed guide tube with and without collision is obtained,which provides a basis for the setting of the sensor response time.At the same time,combined with the working principle and performance parameters of the rapeseed disturbance pneumatic seed metering device,the position and size of the detection surface of the detection system were determined,and the sensor connection device was designed;the overall composition of the detection platform and the structure of the detection system were analyzed by 3D drawing software.overall design.(2)With STM32 microcontroller as the core control module,the overall framework of the detection system hardware is built,the working process of the sensor and the generation principle of the pulse signal are expounded,and the "one-to-one" transmission mode is used to amplify,rectify and monostable the seed stream signal.Triggering,wireless transmission and its stability are optimized and designed.At the same time,signal acquisition,voltage reduction,display circuit and overall system circuit are designed to realize real-time detection of rapeseed seed flow in each row.(3)Determined the overall design of the detection system software,and programmed and debugged the pulse interruption monitoring subroutine,wireless communication subroutine,web page and LCD screen display program,and the calculation of the coefficient of variation of the displacement consistency of each row.At the same time,MQTT communication was used.The protocol link mode is based on the Pygame library to design and write the web page monitoring graphical interface,which realizes the acquisition,processing,transmission and display of the seed stream signal.(4)Huayouza 62 rapeseed was selected as the test material,and the sensor accuracy detection test was carried out in the form of single and double seeds;the six-degree space vibration table was used as the test platform to carry the rapeseed disturbance pneumatic precision seed metering device,the vibration frequency,The speed of the seed plate and the working negative pressure are the test factors,and the relative deviation between the detected value of each row of seed quantity and the coefficient of variation of the consistency of the displacement of each row and the actual value is the evaluation index.The full-factor vibration test is carried out within the range of r/min ～ 60 r/min and working negative pressure of 1500 Pa ～ 2500 Pa.The results showed that the relative deviation of single and double-seed detection test results was 3.67%;the relative deviation between the actual value of each row and the detected value did not exceed 5.0%,and the relative deviation of the uniformity coefficient of variation of each row did not exceed1.0%.The field test showed that the relative deviation of the sowing rate of rapeseed seeds did not exceed 8.0%.The system can work stably in the field operation environment and provide a basis for the quality evaluation of rapeseed sowing.