Simulation and parameter optimisation of a centrifugal rice seeding spreader for a UAV
A centrifugal rice seeding spreader with a baffle ring was designed for an unmanned aerial vehicle (UAV). Rice seeds ejected by a rotating disc are caused to rebound by a baffle ring, to produce a non-hollow, fan-shaped distribution at field level. Three factors produce influences on the distribution, and they are the rotation of the disc, UAV flying height and the angle of the baffle ring. The discrete element method (DEM) was used to simulate the range of the three factors and to explore their influences. Experiments were then conducted using a central composite design (CCD) approach to optimise these three factors. Simulation results showed that the influence of the three factors on distribution uniformity was in the order (most to least); UAV flying height, sowing disc rotation and baffle ring angle. Optimal parameters for the most uniform distribution in simulations were; sowing disc rotation 600 rpm, flying height 2.1 m and the baffle ring angle 26°. The coefficient of variance (CV) achieved was 21.39%. The bench tests were implemented where a CV of 23.24% CV was obtained. Field tests were carried out, and the CV values between 22.21% – 32.90% were obtained because of the influence of the wake of the drone’s propellers. At optimal parameters, the crop yield in the field reached 76,66 kg ha−1 in the field experiment.
Keywords: Agricultural machinery, Discrete element method, Direct seeding, Coefficient of variation, Lateral homogeneity