Design and Experiment of Seed Metering Device for Rapeseed Based on Seeding Frequency Feedback

The seed metering device for rapeseed was the core working part of rape mechanized seeding technology. The performance of seed metering device for rapeseed directly determined the quality of rape seeding. One of the trends to achieve intelligent sowing is to obtain sowing information through real-time detection of rape seed flow and control the sowing volume accordingly. The electronic control seed metering device that used motor speed as the control target had the problem of unstable seeding quantity in real time under complex working conditions. This problem has made it difficult for the seed metering device to achieve the agronomy requirements of sowing quantity. A seed metering device which can perform feedback control based on real-time sowing information was designed to solve this problem. The seed metering device for rapeseed consisted of a screw tube seed rowing mechanism, a detection and control module, a small grain size seed sensing module and a drive module. In order to orderly pass all seeds through the sensing area of the small grain size seed sensing module, the structure of the seed guide tube was designed. This seed guide tube can match the sensor module. It can effectively reduce loss sowing. The seed metering device for rapeseed was tested for rotation speed-seeding frequency measurement and seeding accuracy rate. A seeding quantity compensation model was constructed based on the result of test. This model reduced sowing detection errors. The seed metering device for rapeseed was tested for rotation speed-seeding quantity measurement and seeding accuracy rate. A seeding quantity compensation model was constructed based on the result of test. This model reduced sowing detection errors. A seed metering device control system was designed by using the small grain size seed sensing module to complete real-time seeding information detection, and it used the detected information as input to the control system. The control module calculated based on the set seeding information and the forward speed information measured by the hall speed measurement module. The control module converted the difference between the theoretical seeding frequency and the actual seeding frequency measured in real time by the small grain size seed sensing module into the speed difference as the controller input. The control module decided on the corresponding duty cycle. The bench test showed that the seeding quantity detection accuracy of the seed metering device for rapeseed detection was higher than 98.75% in the range of 10.1~60.4 Hz seeding frequency. The coefficient of variation of seeding quantity stability of seed metering device for rapeseed was less than 1.16% at different rotation speeds. The field test results showed that the error rate of sowing quantity was less than 2.55% and the coefficient of variation of seeding quantity stability of seed metering device for rapeseed was less than 0.98% at different forward speeds of the tractor. This seed metering device for rapeseed provided technical support for precision sowing in small plots. © 2021, Chinese Society of Agricultural Machinery. All right reserved.