Research Of Planetary Gear Train Seedling Pick-up Mechanism Based On Two-unequal-amplitude Transmission Ratio

The advantages of transplanting,the increasing industrialization and standardization of the planting industry has made the market of transplanting machines doubled.As the core component of the transplanting machine the seedling pick-up mechanism is a hot spot of agricultural machinery in the current research.Developing an economical,efficient and reliable seedling pick-up mechanism is the key technology to promote the industrialization of transplanting mechanism.It is also the main task to improve transplanting efficiency,reduce labor intensity and realize transplanting mechanization.The main contents of the paper are as follows:1)Analyzing the research status of the existing seedling pick-up mechanism at home and abroad,and found that the seedling pick-up mechanism has made some progress in the realization of mechanization,but the effect of seedling pick-up is not ideal due to its structure,and it was rare used.The application status of seedling pick-up mechanism of planetary gear train is analyzed.By comparing the design methods and transmission structures of several typical seedling pick-up mechanism of planetary gear train with two-unequal-amplitude transmission ratio,this paper breaks through the method of forward and reverse calculation,and puts forward the research of seedling pick-up mechanism of planetary gear train based on two-unequal-amplitude transmission ratio.2)Through the analysis of the formation principle of seedling trajectory,it is determined that the two-unequal-amplitude transmission ratio is the key to realize the pointed mouth trajectory and the two-unequal-amplitude swing.The cubic non-uniform B-spline curve is used to fit the quadratic unequal amplitude transmission ratio curve and the transmission ratio is distributed freely in two stages.The seedling pick-up trajectory is directly controlled by the total transmission ratio,and the gear pitch curve is directly controlled by the sub-transmission ratio to design the seedling pick-up mechanism that meets the requirements,and the kinematics model is established.3)The kinematics target of the seedling pick-up mechanism was determined,and the software for assistant analysis and optimization of the seedling pick-up mechanism of planetary gear train with two-unequal-amplitude transmission ratio based on MATLAB was developed independently.On the basis of the optimization software,the influence of the two-unequal-amplitude transmission ratio and the mechanism parameters on the trajectory is analyzed,the optimization range of the relevant parameters is determined,and a set of optimization results satisfying the requirements are obtained.4)On the basis of the optimization results,the structure design of seedling pick-up mechanism is completed by using CAXA and AutoCAD,the three-dimensional modeling and virtual assembly of seedling pick-up mechanism are completed by using SolidWorks,and the simulation analysis of seedling pick-up mechanism is completed by using Adams.The simulation results are in good agreement with the theoretical design,which proves the correctness and feasibility of the design of seedling pick-up mechanism.5)The prototype of seedling pick-up mechanism has been trial-produced and experimented.The analysis of the idling experiment verifies the high consistency of the prototype with the theoretical design and simulation analysis.At 120 plants per minute/row,74 seedlings were obtained,72 of which were successful and 2 failed.The success rate of seedling pick-up was 97.3% and the matrix integrity rate was 75.7%.The average success rate of seedling pick-up was 96.63% through the analysis of seedling pick-up experiments at different rotational speeds.The experimental results show that the design seedling pick-up mechanism in this paper is highly reliable and hopeful to realize industrialization in the future.