Design And Experiment Of Seedling Pick-Up Mechanism With Planetary Gear Train Based On Hybrid Multi-Pose

Mechanized planting can effectively free labor and improve planting efficiency,and it is also the foundation for future intelligent agriculture.The existing seedling pick-up mechanism with planetary gear train is mainly designed for 128 cavities,cavity diameter of 32 mm×32 mm,bottom of 18 mm×18 mm and depth of 44 mm cavities,and the angle of swinging of the clamping plate in and out of the cavity is large,so it can not meet the demand of seedling extraction of many types of cavities at the same time,resulting in certain limitations in practical application.In addition,the existing seedling picking arms are too short in length and too slow in speed,which affects the success rate of seedling picking and seedling pushing effect.In this paper,we design a planetary wheel system seedling picking mechanism with a small angle of oscillation before and after entering and leaving the bowl cavity when picking seedlings,so that the seedling picking mechanism can be applied to more types of cavity trays,and propose a gear swing arm that can realize progressive seedling picking and fast seedling pushing to improve the seedling picking success rate and seedling pushing effect of the seedling picking mechanism.The main research contents of this paper are as follows:(1)Analyze the current research status of the automatic seedling picking mechanism at home and abroad,clarify the design requirements of the automatic seedling picking mechanism in this paper based on the current research status of the seedling pick-up mechanism with planetary gear in this subject group,and finally determine the overall plan and technical route of this paper.(2)According to the design requirements of the seedling picking mechanism,we plan a seedling picking trajectory that can achieve a small swing angle,and select ten positional data on the seedling picking trajectory,including four exact positional data and six approximate positional data,and then simplify the seedling picking mechanism to a planar 2R mechanism,establish a hybrid multi-place comprehensive design equation for the planar 2R open chain mechanism,and establish a comprehensive solution objective function based on the design equation.Then,the design equations are solved by Tonglen’s algorithm,and the mechanism parameters of the planar 2R open-chain mechanism are finally solved to meet the design requirements.(3)Based on the solved mechanism parameters,the design of the seedling pick-up mechanism with planetary gear is carried out,including the calculation of the angular displacement curve,the distribution of transmission ratio and the calculation of the non-circular gear knuckle curve,and the planetary wheel system seedling picking mechanism with the swing angle of the seedling picking arm to enter and exit the bowl cavity less than 45°is obtained.Based on the designed non-circular gear knuckle curve,the design of non-circular gears with large overlap is carried out,and the hybrid multi-place synthesis method-assisted design software is developed based on the GUI interface of MATLAB to simplify the design process of seedling pick-up mechanism.(4)Analyze the problems of the existing seedling extraction arm in the process of seedling extraction;determine the design requirements of the new seedling extraction arm according to the agronomic requirements and based on the existing arm,then propose a gear swing arm that can realize progressive seedling extraction and fast seedling push according to the new design requirements,and briefly describe its basic composition and working principle,and finally determine the mechanism of the gear linkage mechanism and cam in the gear swing arm.parameters.(5)The structural design and 3D model of the seedling picking mechanism are established,and the kinematic simulation of the virtual prototype is carried out based on the 3D model to obtain the simulated seedling picking trajectory of the seedling picking mechanism and verify the consistency between the theoretical design and the simulation results,and to analyze the simulation process of clamping the potted seedlings by the gear pendulum seedling picking arm to verify the feasibility of the gear pendulum type seedling picking arm design.(6)Machining,assembling and debugging the prototype of seedling picking mechanism,building the test bench of seedling picking mechanism,and conducting the idle test of seedling picking mechanism to obtain the actual seedling picking trajectory and compare it with the theoretical and simulated trajectories to verify the correctness of the theoretical design.Finally,the seedling extraction test was carried out for small cavity trays with 25 mm×25 mm cavity opening size at different rotational speeds,and the successful seedling extraction rates of 97.1%,95.0% and 94.4% were obtained at 25r/min,35 r/min and 45 r/min,respectively.