Development of high-speed and precision metering device with gradient-feeding and control seed for soybean planting

High-speed and precision planting was employed to improve the yields of soybean seeds. However, most mechanical seed metering devices had a lower quality index under high-speed. In this study, a high-speed and precision metering device with gradient-feeding (GF) and control-seed (CS) for soybean planting was designed to improve the quality index at high speeds. GF was designed to make soybean seeds rapidly enter seed cells. CS prevented soybean seed that was to be released from being cleared during the clearing stage. Firstly, the range of working parameters of it was determined by theoretical analysis, which included the angle of guiding-slope (α), the angle of seed-control (θ), and mutation height (∆H). Then, orthogonal center combination tests with three-factor and five-level were carried out to determine the corresponding quality index and miss index with different working parameters. The optimal working parameters were determined by regression equations between the quality index and the miss index. The high-speed and precision metering device with GF and CS was thus manufactured based on these optimal working parameters. The simulation test and bench test of it were carried out with different forward speeds of the planter. The results showed that the optimal angle of guiding-slope (α), angle of seed-control (θ), and mutation height (∆H) were 18.06°, 136.67°, and 2.77 mm, respectively. In the bench test, all quality indices were higher than 95.00%, and all miss indices were lower than 3.00% when the forward speed of the planter was 4 - 16 km/h. The results of the bench test were consistent with the results of the simulation test, with an average relative error of 2.33%. High-speed and precision metering device with gradient-feeding (GF) and control-seed (CS) can realize precision planting at high speeds.