Optimal Design And Experiment Of High-Speed Duckbill Planting Mechanism With Variable Catch-seedling Attitude

China is the world’s largest vegetable producing country.In order to increase the degree of automation of vegetable transplantation,vegetable seedling transplantation has been vigorously promoted,but most of the vegetable transplantation is manual and semi-automatic transplantation,and most of the domestic use semi-automatic transplanters which the seedlings are picked manually and put into the planting mechanism to complete the planting.Therefore,the main f actor restricting the efficiency of the duckbill planter mechanism is the low speed of feeding the seedlings.Therefore,it is imperative to develop a high-speed automatic transplanter,and the planting mechanism is an important component of automatic tran splantation machine,the current design difficulty of high-speed transplantation lies in the fact that the automatic seedling-picking mechanism and the planting mechanism cannot accurately cooperate in the work,and the rapid downward of the pot seedlings contradicts the higher level speed of the duckbill.In order to improve the planting efficiency of the planting mechanism,a high-speed duckbill planting mechanism with variable catch-seedling attitude was proposed for the duckbill planter trajectory and attitude.After the optimization,a "droplet-shaped" relative trajectory was made to reduce the speed and change the attitude of the duckbill planter when the seedli ngs were planted.The duckbill mouth was always aligned with the direction of the seedlings to solve the problem of mismatch.And it provides a new idea for the vegetable transplanting mechanism.The main contents of this paper are as follows:(1)According to the current demand analysis,based on the existing research,a high-speed duckbill planting mechanism with variable catch-seedling attitude was proposed.Non-circular gears and duckbill planting mechanism were combined to achieve non-equid speed transmission to obtain better speed and acceleration characteristics,shorten the time to transport seedlings,and achieve the trajectory and attitude required by design.The structure of the mechanism is simple and the operation effect is good.(2)The working principle of the planting mechanism was discussed,the design scheme,design requirements and constraints were established,the kinematic model of the mechanism was established,the optimization goals were set,and the theoretical basis was provided for the subsequent optimization design.(3)Based on the kinematics model and optimization goals of the planting mechanism,relied on Visual Basic 6.0 software,computer-aided optimization software for the high-speed duckbill planting mechanism with variable catch-seedling attitude was developed.Through optimization,a new type of "droplet-shaped" relative trajectory that meets agronomic and design requirements was obtained,and a set of mechanism parameters that meet planting requirements were obtained.(4)According to the obtained parameters,Auto CAD was used to carry out the overall two-dimensional design of the planting mechanism and the design of key components.According to the design,UG NX8.0 was used to perform three-dimensional modeling and model interference checking,and imported the model into the ADAMS simulation software to perform relative and absolute movement of the planting mechanism kinematics simulation.(5)The swing angle of the duckbill planter during the periodical operation,and the speed curve formed by catch-seedling point of the planter and the tip point of the planter were analyzed,and the rationality of the planting mechanism design was verified.(6)3D printing technology was used to process some parts assembled into a physical prototype.and a high-speed photographic bench test on the physical prototype was performed.By comparing the theoretical trajectory,trajectory simulation and actual work track,the theoretical model’s possibility was verified.(7)The seedlings of bell pepper was took as test crops and the physical characteristics of the seedlings was analyzed.Through the seedling-planting test,the qualified rate of planting was99.8% and the qualified rate of planting depth was 99.2%,which verified the practicabi lity of the mechanism.