Design And Test Of An Intra-row Weeding Mechanism For Planetary Gear Train With Non-circular Gears

Weeds in farmland have huge root systems and have strong ability to compete with field crops for water,nutrients and growth space.They have a deep hazard to agricultural production.Therefore,field weeding is an important task in agricultural production activities.In recent years,mechanical weeding technology has aroused much concern.Compared to the chemical weeding and manual weeding,it is environment-friendly and has high weeding efficiency.Field weeds can be divided into inter-row weeds and intrarow weeds according to their growing positions.At present,inter-row mechanical weeding technology has been quite mature.However,due to the fact that intra-row weeds are close to crops and the intra-row weeding area is discontinuous,it is difficult to remove weeds in the intra-row area by mechanical weeding,so intra-row mechanical weeding technology has been slow to development.Therefore,intra-row weeding is the difficulty of mechanical weeding,and it is of great significance to improve intra-row mechanical weeding technology for sustainable agricultural development.Based on the analysis of the research status of domestic and international intra-row mechanical weeding technology,this paper proposed a planetary gear intra-row weeding mechanism based on non-circular gears which can actively avoid seedlings in order to solve the problems existing in the intra-row mechanical weeding device in China,such as low slop removal,high seedling damage rate,complex structure and poor adaptability to the variation of plant spacing.The main structure of the mechanism was designed and optimized.The main research contents of this paper are as follows:(1)According to the agronomic requirements of intra-row weeding,the working path of weeding execution unit in intra-row weeding operation was planned by using the idea of rotating seedling avoidance and the working principle of avoiding crops during weeding was explained.(2)Based on the planned motion path of the weeding execution unit,an intra-row weeding mechanism with non-circular gear planetary gear train was designed,and the weeding knife,transmission scheme and the adjustment mechanism of cutter’s entry angle of the mechanism were designed and analyzed.(3)Establish the kinematics model of the intra-row weeding mechanism,and for the "cashew shaped" weeding knife designed in this paper,the structural parameters of the knife were optimized by response surface method and satisfaction function method;A MATLAB-based auxiliary analysis software was developed to optimize the pitch curve of non-circular gears,and through man-machine interaction,a set of radial values of noncircular gear pitch curve which meet the design requirements were obtained.(4)The EDEM discrete element software and ADAMS dynamic software were used to carry out the co-simulation,which was used to analyze the change of working resistance when the weeding knife cut the soil under different machine forward speed,the angle of the knife into the soil and the edge angle of the knife.And take the machine forward speed,the knife into the soil angle and the knife edge angle as the test factors,and the average working resistance of the weeding knife when cutting the soil as the test index.By using the range analysis method,a group of factors with lower average working resistance were optimized.(5)According to the optimized parameters,the three-dimensional model of the intrarow weeding mechanism was created and the virtual prototype simulation analysis was carried out to verify the correctness of the mechanism design and theoretical analysis.Finally,the various parts of the intra-row weeding mechanism were processed,and the processed parts were assembled into a physical prototype,and the prototype was tested and analyzed to verify the feasibility of the mechanism design.