Double-setting Seed-metering Device For Precision Planting Of Soybean At High Speeds

For the problems of bad impacts for filling,clearing seeds and the non-uniformity of seed spacing of traditional mechanical seed-metering device under the condition of high-speed operation,this paper proposes a new method of quantitative constraint seed selection,taking seeds quantificationally,active quantitative seed clearing and prerelease adaptive principle from the perspective of guiding seed filling,actively isolating seeds to be seeded and seeds to be cleared and controlling seed feeding point.In order to obtain the design parameters and performance of soybean precise seed metering device for high speed operation and provide the basis for the design of soybean seeding machine,a double-setting seed-metering device for precisely planting of soybean at high speeds is designed.The main research contents and conclusions are as follows:（1）Structural parameter design of double-setting seed-metering device for precision planting of soybean was conducted at high speeds.In view of the problems in the existing mechanical precision seed metering device,combined with the requirements of precision seeding agronomy,a double-precision high-speed precision seed metering device was designed.The structure and working principle of the seed metering device were analyzed and determined.Structural parameters of key components such as seed（the lengths of the first and second setting plates,the seed cell angle?;the seed holder angle?）,inoculation cup and shielding plate.（2）Work process simulation and experimental research of double-setting seed-metering device for precision planting of soybean was conducted at high speeds.Single factor test and uniform design test were carried out by discrete element simulation method,and the main factors affecting seed filling,seed clearing and seed arrangement qualification rate were determined by multiple nonlinear regression analysis,and the regression equation between the influencing factors and seed arrangement qualification rate was established.Experimental results showed that the most influential factors were?and L₂（the lengths of the second setting plates）and their interactions.The best performance,represented by highest qualified rate of seed metering,occurred at L₂=5.18 mm and?=61.9°,where the qualified rate was 99.59%.The model results agreed well with the test results,as demonstrated by the low relative error（2.5%）.When the advance speed of the seeder is 8km/h¹1km/h,the qualified rate of seed row is 96.16%,98.04%,97.09%,97.09%,and the variance is 3.29%,1.85%,0.30%,and 0.29%,respectively.（3）Simulation and Experimental Study on Seeding and guiding device of double-setting seed-metering device for precision planting of soybean was conducted at high speeds.Through simulations using the model,the primary and secondary factors of impacting the qualified rate of seed metering and the coefficient of variation of the seed spacing uniformity were identified,and they were,in descending order,the spacing of the prerelease,the start position of the prerelease,the inclination angle of the seed outlet,and the inclination angle of the receiving cup.Then,regression equations of the qualified rate of seed metering and the seed spacing uniformity with the two main impacting factors were established.For a planter travel speed of 10km/h,the optimal spacing of the prerelease was10mm,and the optimal start position of the prerelease was 40°,where the qualified rate of seed metering was 100%and the seed spacing uniformity was 16.61%.When compared to those without double-curved guiding groove,the seed spacing uniformity reduced by2.55%,showing that the double-curved guiding groove significantly improved the uniformity of seed spacing.