Optimized design and experiment of the three-arm transplanting mechanism for rice potted seedlings

The transplanting arm of two-arm transplanting mechanism is easy to cause seedlings injury and missing due to its faster speed relative to the seedlings.In order to solve the existed problems,a three-arm transplanting mechanism for rice potted seedlings was developed in this study.The developed three-arm transplanting mechanism for rice potted seedling can make the transplanting arm realize special trajectory and attitude through the unequal planetary gear transmission.The kinematic model of three-arm transplanting mechanism for rice potted seedling was established,and the optimal design software was developed.Based on the heuristic optimization algorithm named“parameter guide”,a set of satisfied mechanism parameters required by the rice potted seedling transplanting were obtained.The trajectory and attitude of three-arm transplanting mechanism used for the rice potted seedling were analyzed.Besides,the virtual simulation results were basically consistent with the optimization software results,and the correctness of theoretical analysis and virtual simulation were also verified by each other.When the developed transplanting mechanism picked up the seedling,the velocity of transplanting arm relative to the seedling was reduced by about 30%.The results showed that the injury rate of rice potted seedling transplanting mechanism was 0.04%,the missing rate of seedling was 1.4%,the integrity rate of seedling pot matrix was 96%,and the success rate of picking seedling was 99.92%.

Design of clamping-pot-type planetary gear train transplanting mechanism for rice wide-narrow-row planting

To design a clamping-pot-type wide-narrow-row pot seedling transplanting(WPST)mechanism with desired spatial beak-shaped trajectory and working posture,a new design method of planetary gear train transplanting mechanism(PGTM)with non-circular gears based on several key spatial poses(position and posture)was proposed.The PGTM was simplified to a spatial open-loop chain with two-revolute(2R)joints.The geometric constraint equations containing only the structural parameters of the chain were then established on the basis of the three key spatial poses,and the homotopy algorithm was used to obtain all the required parameters of the mechanism.In accordance with the parameters obtained,the relative angular displacement relation between the planet carrier and the transplanting arm was optimized,the trajectory of the mechanism was replayed,and the total transmission ratio was determined.The degree of freedom of the spatial 2R mechanism was reduced by attaching to the unequal gear pair,and the transmission ratio was distributed in accordance with the gear type to realize the design of a non-circular gear pitch curve.Lastly,a clamping-pot-type PGTM for rice WPST driven by the combination of planar non-circular and non-conical gears was designed,and virtual simulation and prototype test were conducted.Results showed that the simulation and prototype test trajectories were consistent with the desired trajectory.Under the operating speeds of 50 r/min and 90 r/min,the success rates of seedling picking were 95.32%and 90.15%,respectively,which verified the feasibility of the theoretical method.This method could provide a reference for the design of a spatial PGTM with nonuniform transmission.