Design And Experiments Of A Pot Seedling Planting Mechanism For Vegetables With Small And Medium Plant Spacing

China sits on the throne of vegetable production in the world,and it also ranks first in the world at vegetable cultivation area.Seedling raising and transplanting are important segments in the process of vegetable cultivation.More than 60% of vegetable varieties adopt the cultivation method of seedling raising and transplanting.Mechanized transplanting can not only reduce labour costs and improve production efficiency,but also plant seedlings with consistency on row spacing,plant spacing and depth,which can realize a standardized management of the whole vegetable production process,to improve the quality and yield of vegetables.Seedling planting mechanism is the primary operating mechanism of vegetable transplanter,and the planting quality of seedlings is directly affected by how it performs.However,at present,seedling planting mechanisms are mostly used for vegetable transplanting with large plant spacing(greater than 300 mm),which cannot meet the needs of planting vegetables with small and medium plant spacing.Therefore,this study proposes and designs a non-circular gear planetary gear train seedling planting mechanism which is capable of meeting the planting requirements of small and medium plant spacing for vegetables transplanting,and carries out the development of kinematics modeling,parameter optimization,simulation analysis,prototype trial production and experiments.The specific study contents are as follows:1)Dryland transplanters’ research status both home and abroad is discussed,and the structural characteristics,working principle,advantages and disadvantages of representative automatic seedling planting mechanism at home and abroad were analyzed and summarized.According to the planting requirements of small and medium plant spacing for vegetable pot seedlings,the posture requirements of the planting motion trajectories(static trajectory and dynamic trajectory)required for small and medium plant spacing vegetable pot seedlings are put forward,and then the overall design requirements of planting mechanism are determined.2)Taking in consideration the design criteria of the pot seedling planting mechanism,the overall design scheme of a pot seedling planting mechanism of vegetables with medium and small plant spacing is determined,including the two-stage non-circular gear transmission scheme and the duckbill planter’s opening and closing mode.This study expounds the working principle of pot seedling planting mechanism of vegetables with medium and small plant spacing and establishes its kinematic model.3)Using the established mechanism kinematics model and based on Visual Basic6.0 software platform,the auxiliary analysis and optimization design software of pot seedling planting mechanism for vegetables with medium and small plant spacing is developed.The influences of the main mechanism parameters on the planting motion trajectories and postures of the seedling planting mechanism are analyzed,and a set of parameters belonging to the mechanism and that can satisfy the planting requirements of small and medium plant spacing for vegetable pot seedlings are optimized by interaction between computer and human.4)By taking the optimized parameters of the pot seedling planting mechanism obtained as basis,the structure of the pot seedling planting mechanism for vegetables with medium and small plant spacing is designed,its three-dimensional model is constructed,and its virtual prototype simulation is carried out.The simulation results are mostly compatible with the theoretical design,indicating that the design of the pot seedling planting mechanism is correct and feasible.5)The machining and assembly of the planting mechanism physical prototype for vegetables pot seedlings with medium and small plant spacing are completed,and the kinematic characteristics test and pot seedling planting test of the mechanism are carried out on a test bench.The results obtained from the experiments prove that the mechanism’s actual motion trajectory and attitude are mostly in line with the theoretical design and simulation outcomes.The seedling planting efficiency is 90 plants /(min · row).When the theoretical plant spacing of 225 mm is set,the planting success rate is 97% and the overall planting success rate is 95%,which meets the planting requirements,and verifies the feasibility and practicability of the designed pot seedling planting mechanism.