| The full mechanized operation of the scallion industry can significantly improve its economic benefits.It can save cost and improve efficiency by using a planetary gear train transplanting mechanism with high efficiency,abundant working track and mature technology to replace the human hand to complete the seedling feeding work in the scallion transplanting process.In order to realize the large displacement and large angular motion requirements of the automatic seedling feeding operation of the scallion,the asymmetric high-order transmission is put forward,the law of asymmetric transmission ratio and the design method of asymmetric transmission ratio highorder non-circular gear train are studied,and an asymmetric high-order non-circular planetary gear system mechanism is designed to be used in scallion seedling feeding operation,a model for calculating the parameters of planetary gear system mechanism based on precise pose points and trajectory shape control points is established.The mechanism aided design and optimization software was developed by using the GUI module of MATLAB.The trajectory requirement of seedling feeding and the concave-convex requirement of gear pitch curve are taken as the optimization objective for selecting the optimum parameters which are used to determine the transmission ratio and mechanism parameters of gear train,the gear pitch curve is obtained according to the transmission ratio.The 3D model of the mechanism was established and simulated,and the prototype was machined and tested.The main research contents of the thesis are as follows:1)The design method of high-order non-circular gear pair with asymmetric gear ratio is studied.The structure and working principle of the gear pair are analyzed.Based on this,an asymmetric high-order non-circular gear planetary system is proposed.2)Combined with the rigid body guidance theory of planar linkage mechanism,a design method of transplanting mechanism based on precise pose and trajectory control is proposed: according to the given precise pose condition,the hinge point solution curve is established and the mechanism parameter solution domain is established.After the track shape control point is introduced,the mechanism is identified and the domain is filtered.The total gear ratio of the wheel train is calculated to design the gear section curve.The theoretical design model of the asymmetric high-order non-circular gear planetary system onion seedling feeding mechanism was established by this method.The mechanism parameter solution domain was obtained,and the design method of high-order non-circular gear pair with asymmetric transmission ratio was used to design the gear pitch curve.3)The trajectory of seedling feeding of the green onion seedling mechanism was analyzed,the kinematics goal of the organization was determined,and the optimization principle of the mechanism parameter solution was established.The MATLAB GUI module was used to design the comprehensive design and optimization software of the mechanism parameters to realize the visual output of the design results,and the optimal mechanism parameter solution of the green onion seedling mechanism was obtained.4)The 3D modeling software Solidworks was used to design the asymmetric high-order noncircular planetary gear system scallion transplanting mechanism,The virtual simulation experiment of the scallion transplanting mechanism was carried out by Adams software to verify the correctness of the mechanism structure design,the scallion transplanting mechanism physical prototype was processed and a test bench was established,high-speed photography test and scallion seedling test was carried out,and finally the results of the experiment and theory was compared and analyzed,The attitude angles of the seedling-taking arm are 167.41 degrees,157.43 degrees and 17.26 degrees respectively when the mechanism passes through the key working points,which are 2.41 degrees,2.43 degrees and 2.26 degrees different from the theoretical values.Within the allowable error range,the correctness of the design method of planetary gear train transplanting mechanism based on precise position and trajectory control is verified. |
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