Structural Design And Optimization Of Famous Tea Picking Robot

Famous tea has developed rapidly in China and become the leading product of China’s tea industry,while famous tea fresh leaves must have high quality standards.At present,famous tea fresh leaves are manually picked,and the picking is cyclical and seasonal,which requires a large amount of manpower.However,with the migration of labor population to cities,human resources are increasingly lacking.At present,the existing fresh tea picking machinery on the market can improve the picking efficiency,but it lacks selectivity,and the picked fresh leaves are mixed with old and new leaves,and cause mechanical damage to the tea tree.Therefore the existing fresh tea picking machinery cannot meet the quality standards of famous tea buds and leaves.In this paper,on the basis of the existing tea picking machinery and agricultural picking robot,combined with parallel robot technology and quality standards of famous and excellent tea,a self-walking parallel tea picking robot for picking famous and excellent fresh teas was proposed and could be used to selectively pick fresh tea.The specific research contents are as follows:（1）Designing the overall scheme and structure of the famous and excellent tea picking robot.In this paper,the stucture of tea garden and the standard of picking fresh leaves of famous and excellent tea were analyzed and the overall design of famous and excellent tea picking robot was proposed.A crawler walking mechanism which could adapt to mountain walking and its supporting adjustable frame was designed and the frame intensity was analyzed by finite element method.The results showed that the frame design structure met the strength of picking condition.Delta manipulator scheme was made,and the parameters of the manipulator were preliminarily determined,and the static platform radius was 95mm,the active arm length was 210mm,the driven arm length was 520mm,and the moving platform radius was 55mm.In order to solvet the problem that the side fresh leaves could not be picked at present,a set of multi-degree-of-freedom end-effector with a small manipulator was designed to pick the top and side fresh leaves,to sure that its picking range could cover the top and side fresh leaves.The tip of the end-effector was made by flexible material to avoid damaging the tea leaves and affected the quality of the picked leaves during clamping.（2）Space vector method and geometric method were used to establish the theoretical model of Delta mechanism.The simplified model of Delta manipulator was established,and the forward and inverse kinematics model of Delta manipulator were established by vector method and geometric method.MATLAB platform was used to calculate the relevant model.Within the allowable Angle range of the driving joint,a certain step size was set to traverse the spatial reachable position coordinates of the center point of the moving platform of the manipulator,and the scatter diagram and envelope surface of its workspace were drawn.The calculation results showed that the working space of Delta parallel manipulator was a three-curved semi-ellipsoid,and the range of reachable directions in the space was X_min=-351.9742mm,X_max=351.9742mm.Y_min=374.3642mm,Y_max=379.8516mm;Z_min=222.6392mm,Z_max=-728.9048mm and envelope volume was 0.26m³.The calculation space range can include tea distribution space.（3）ADAMS virtual prototype was used to verify the reliability of the designed structure.A three-dimensional model of tea picking robot was established by Solid Works software,which was imported into ADAMS kinematics simulation software.Material attributes of each component were defined,and motion constraints such as rotation and sphere were imposed,and gravity environment was configured.Forward simulation was carried out by applying drive to the driving joint,and reverse simulation was carried out by applying point drive to the center point of the moving platform.The forward and inverse simulation results showed that the running process of the manipulator was smoothly stable,and the components did not interfere with one another,and the kinematics performance was very good.MATLAB combined with forward and inverse solution model was used to verify the simulation results.The results showed that the theoretical calculation value is basically consistent with the simulation results,which verified the reliability of the design scheme.（4）Genetic algorithm was used to optimize the structure of the manipulator and prototype test was carried out.The actual demand of tea picking was analyzed and the tea distribution space of the working space could precisely covering was used as the optimization goal of the manipulator.MATLAB genetic algorithm toolbox was used to construct the optimization objective function and constraint function,and four parameters including active arm length,driven arm length,static and dynamic platform radius difference and coordinate system height were optimized.The optimal structural parameters of the parallel manipulator were obtained as follows:The length of the active arm was230mm,the length of the driven arm was 550mm,the radius of the static platform was 95mm,the radius of the moving platform was 45mm,and the moving platform was 320mm away from the top of the tea tree while picking.The experimental results showed that the prototype could pick the space covered by tea distribution and meet the actual demand of picking.