Double-Setting Seed-Metering Device for Precision Planting of Soybean at High Speeds

Abstract. Precision planting has been proven to be an effective method for seeding row crops with uniform seed spacing, which favors crop yields. However, most precision planters were developed for low field operating speeds. In this study, a mechanical seed-metering device was developed with double-setting seed pickers, which allows high-quality planting at high field operating speeds. A discrete element model (DEM) was used to examine the effects of the design parameters on the metering performance, as indicated by the quality index (I q ), miss index (I miss ), and multiples index (I mult ). Based on the model results, a seed-metering device was fabricated with the optimal design parameters and tested in laboratory conditions for model validation. Results showed that the critical parameters for the seed picker design were the lengths of the first and second setting plates (L 1 and L 2 , respectively) and the seed cell and seed holder angles (a and ß, respectively). The I q was generally high and the I miss and I mult were generally low over the ranges of L 1 from 15.5 to 17.5 mm, L 2 from 4.6 to 5.5 mm, a from 57.5° to 65.0°, and ß from 50.0° to 70.0°. The most influential factors were ß and L 2 and their interactions. The best performance, represented by the highest I q , occurred at L 2 = 5.18 mm and ß = 61.9°, where the I q was 99.59%. The model results agreed well with the test results, as demonstrated by the low relative error (2.5%). Keywords: DEM, Modeling, Precision metering, Quality index, Seed, Travel speed.