DEVELOPMENT OF A GUIDING-GROOVE PRECISION METERING DEVICE FOR HIGH-SPEED PLANTING OF SOYBEAN

Precision planting is the inevitable trend of agricultural development, and the promotion of precision planting technology is the key to increasing crop yields. 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 is the guiding-groove (GG) that provides "waiting areas" for seeds to form a line and subsequently enter the seed cells in an orderly and rapid manner. Using force analysis, a mechanical model of the seed feeding stage was developed. Relationships between the design parameters of the GG metering device and its 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 central composite design (CCD). The relationships were then used to determine the design parameters to achieve the best metering performance. With these design parameters, the GG metering device was fabricated and evaluated using bench tests. Results showed that the critical design parameters were the width of the guiding-groove (L-1), angle of the groove bottom surface to the horizontal plane (eta), width of the groove wheel (L), and cone angle of the shell (delta). The relationship between these parameters and the metering performance could be described by a second-order polynomial equation, and the best metering performance occurred with L = 25.3 mm, eta = 8.3 degrees, L-1 = 8.1 mm, and delta = 23.6 degrees. The bench test results showed that the GG metering device designed with these optimal parameters had metering performance values (quality index) of 93% and higher at 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%.