Dynamics Analysis And Experiment Of Spatial Planrtary Gear Train Seeding Taking Mechanism

As a key component of the automatic transplanting machine,the automatic seedling picking mechanism determines the working efficiency of the automatic transplanting machine.The research on the performance of the seedling picking mechanism is of great significance to the development of the automatic transplanting machine.Therefore,this thesis takes the spatial planetary gear train seedling taking mechanism as the object of dynamics research,which provides a theoretical and experimental basis for the performance optimization of the seedling picking mechanism.The main contents of this research are as follows:(1)Through the analysis of the research status of the seedling picking mechanism of the automatic transplanting machine at home and abroad,the advantages of the spatial planetary gear train seedling taking mechanism and the blank of its dynamics research are clarified.Aiming at the working mechanism of the seedling picking mechanism of the space gear train,the modeling method using the dynamics static analysis method and the dynamics equation sequence solution method is clarified,and the rigid body dynamics model of the seedling picking mechanism of the space planetary gear train is established,and the seedling picking mechanism is used to the variance of the three-way support reaction force of the frame of the mechanism and the maximum input moment are used as the criteria for judging the dynamics performance of the seedling picking mechanism.(2)Carried out the kinematics research of the spatial planetary gear train seedling taking mechanism.According to the space motion characteristics of the seedling picking mechanism,the construction of the dynamics coordinate system of the mechanism was completed based on the D-H parameter method,and the size and center of mass of each component of the seedling picking mechanism were completed.For the measurement of coordinates and other parameters,the kinematic relationship and related parameters of the cam fork action in the seedling picking arm are solved based on the numerical method,and the solution and analysis of the kinematic parameters of the center of mass of each component are completed through coordinate changes.(3)The dynamics research of the spatial planetary gear train seedling taking mechanism was carried out,the seedling picking resistance was measured experimentally and the force increase coefficient when picking seedlings was determined by linear regression.Based on the dynamic static analysis method and the dynamics equation sequence solution method,according to the working characteristics of the different working stages of the seedling picking mechanism,different modeling methods are used to model the mechanical conditions of the seedling picking arm,and the gear is completed based on the coordinate change.The modeling of the meshing dynamics model has completed the force summary of the planet carrier and the sun gear,and finally completed the dynamics modeling of the whole mechanism.Based on the above-mentioned mechanism modeling method,the solution program is compiled in Matlab and the solution of each dynamic parameter is completed.(4)Analyze the dynamics results of the solution.In terms of the analysis of the source of the change in the support reaction force,it is clear that in the stages of transporting seedlings and returning,the rotary motion of the mechanism is the main cause of vibration,while in the stages of taking seedlings and pushing seedlings,the mutual mechanical relationship of the internal components of the seedling-taking arm has a great influence on the mechanics of the seedling-taking mechanism.In view of the above situation,the calculation of the optimal solution and the structural design of the counterweight of the seedling arm were completed,so that the variance of the three-axis theoretical support reaction force was reduced by 48.27%,51.29%,and 59.30%,respectively,and based on the working principle of the flywheel The counterweight design of the planet carrier is completed.(5)Established a virtual prototype model of the spatial planetary gear train seedling taking mechanism,set constraints,driving and other settings,compared the simulation and theoretical results of various mechanical parameters,analyzed the characteristics of the theoretical and simulation models,and analyzed The main cause of vibration is determined,and the relative error between the filtered simulation model and the theoretical model is calculated.The maximum error is 8.46%,which verifies the correctness of the theoretical model.(6)Design,manufacture and build a dynamics experiment plantform for the spatial planetary gear seedling picking mechanism,complete the experimental measurement of the dynamics performance parameters of the seedling picking mechanism,and verify the correctness of the theoretical model;optimize the seedling picking mechanism The dynamics test measurement was completed,and the variance of the support reaction force in each axis direction was reduced by 53.76%,76.98%,and 77.17%,respectively,and the maximum input torque was reduced by 5.33%,which verified the effectiveness and feasibility of the optimization scheme.