Development of a Guiding-Groove Precision Metering Device for High-Speed Planting of Soybean

Highlights To improve the performance for precision planting of soybean at high speeds, a guiding groove precision metering device was developed. The seed feeding and clearing processes were analyzed to determine the critical design and operational factors. The effects of critical metering parameters on the meter performance were simulated using the DEM. The metering performance was evaluated using bench tests. ABSTRACT Precision planting is the inevitable trend of agricultural development, and the promotion of precision planting technology is the key to increase crop yield. To improve the performance of precision planting at high speeds, a mechanical-type precision metering device was developed for soybean. The innovative feature of the device was the guiding-groove (GG) that provided “waiting areas” for seeds to form a line and subsequently enter the seed cells in an orderly and rapid fashion. By the force analysis, mechanical model of seed feeding stage was set up. Relationships between design parameters of the meter and the metering performance (multiple index, miss index, quality index and feeding efficiency index) were obtained through simulations using a discrete element model (DEM). The simulations conducted in this study were based on the central composite design (CCD). Then, the relationships were used to determine the design parameters to achieve the best metering performance. With these design parameters, the GG meter was fabricated and evaluated through bench tests. Results showed that the critical design parameters were the width of inner groove-wheel (L), cone angle of the shell (δ), the width of guiding-groove (L1), and the angle of the groove bottom surface to the horizontal plane (ɳ). The relationship between these parameters and metering performance could be described by a second-order polynomial equation, and the best metering performance occurred when L=25.3 mm, δ=23.6°, L1=8.1 mm and ɳ=8.3°. The bench test results showed that the GG meter designed with these optimal design parameters had metering performance values (quality index) of 93% and higher over planter travel speeds of 8 to 15 km h-1. In addition, the coefficients of variation of metering performance over the range of planter travel speeds were lower than 30%.