Mechanism of high-voltage electrostatic adsorption seeding for vegetable seedlings and optimization of system parameters

Aiming at the existing air suction hole tray seedling sowing machine in the face of more impurities and no pill granulation irregular small particle vegetable seeds there are suction holes clogging and lead to the decline in the accuracy of seed discharge technical problems. In this study, a vegetable seedling planter based on high-voltage electrostatic adsorption characteristics was designed by discarding the small aperture and long conductance suction holes. The dielectric insulating layer material is determined by theoretical analysis and simulation tests of potential contour distribution. The results show that: as the relative dielectric constant of the dielectric insulating layer gradually increases, the distribution of equipotential lines between the type hole and the seed box is gradually dense, the potential difference gradually increases, the electric field is gradually strengthened, and the electrostatic adsorption force on the polarised seeds gradually increases, and the adsorption state becomes more and more stable; Construct a mechanical model of electrostatic adsorption, clarify the main factors affecting the electrostatic adsorption force and their interrelationships. The results show that the main factors affecting the size of the effective electrostatic adsorption force in the pore are the output voltage of the electrostatic generator, the hole machining diameter, the material of the dielectric insulating layer, the relative permittivity of the seed layer, the spacing between the pore and the seed layer, and the material of the electrode sheath and the inner and outer diameters of the pore. And determine the electrical parameters and ranges affecting the seeding performance; A three-factor, three-level Box-Behnken centre combination test was carried out with the hole machining diameter, positive high-voltage electrostatic generator output voltage and tilt angle of the seed box bottom as test factors, and sowing pass index, reseeding index and leakage index as response indicators. The results showed that the order of influence of the test factors on the sowing compliance index was the output voltage of the forward high-voltage electrostatic generator, the hole machining diameter, and the tilt angle of the bottom of the seed box; and the order of influence on the reseeding index and the leakage index was the hole machining diameter, the output voltage of the forward high-voltage electrostatic generator, and the tilt angle of the bottom of the seed box. The interaction terms of the diameter of the pore processing and positive HVEG output voltage had significant effects on seeding pass index, reseeding index and leakage index. Mathematical models were obtained between the test factors and the response indicators. Applying Design-Expert 10.0.4 software to optimise the mathematical regression model with multiple objectives, the best parameter combinations were obtained as follows: the hole machining diameter 5.91 mm, positive high-voltage electrostatic generator output voltage 17.67 kV, and tilt angle of the bottom of the seed box 14.69°, and the sowing qualification index at this time was 91.13%, the reseeding index was 3.02%, and the omission index was 5.85%; In the seeding performance verification test, the seeding pass index decreased by 0.61 percentage points, the reseeding index decreased by 0.17 percentage points and the missed seeding index increased by 0.78 percentage points compared to the optimised results. The test error is within the permissible range, and the parameter optimization results are reliable and meet the technical requirements of precision sowing. The results of the study can provide a reference for the research and development of mechanical equipment for precision sowing of vegetable seeds with irregular small particles, and at the same time, provide an academic reference for the research of quantitative adsorption and rapid separation methods and equipment development of irregular small particles materials. © 2024 Chinese Society of Agricultural Engineering. All rights reserved.