Study On Optimization Design And Test Of Transplanting Mechanism For Rice Pot-Seedling

Transplanting mechanism for rice pot-seedling with complicate kinematics principle andmany requirements of work performance is the core work part of the rice transplanter thatdetermines its transplanting quality. A type of transplanting mechanism of planetary gear trainwith elliptical gears and incomplete non-circular gear was designed by author’s research group.The parameters optimization mathematical model of this rice pot-seedling transplantingmechanism has characteristics of nonlinear, fuzzy and strong coupling, When using optimizationmethods of genetic algorithm and neural network, it is very difficult to determine the weightedvalue and penalty factor of objectives because it relies on not only the punishment function toapproach the extremum but the optimization problem itself. So the human-computer interactionoptimization method was applied to optimize the kinematics parameters of transplantingmechanism for rice pot-seedling. However, when using this optimization method, it may needdesigners with a deep understanding of the optimization parameters and objectives. Its universalapplicability is not good and optimization efficiency is very low. In addition, although theoptimized transplanting mechanism can meet seedling transplanting requirements throughseedling pick-up test, there also exist the problems of long time of seedling pick-up and noseedling pushing device, so the efficiency of seedling pick-up and pushing is not good. On thebasis of analyzing shortcomings of different optimization methods, the method of parametermodification guiding optimization and quantizing fuzzy performance of optimization objectiveswas conbimed to optimize parameters of the rice pot-seedling transplanting mechanism. Relativetests were carried out and structure of the mechanism was improved. The main research contentsand results are as follows.1) The work principle and structure of rice pot-seedling transplanting mechanism ofplanetary gear train with elliptical gears and incomplete non-circular gear was introduced, and itskinematics mathematical model was set up.2) The kinematics optimization objectives of the rice pot-seedling transplanting mechanism have been studied according to the requirements of its motion interference, effect oftransplanting pot-seedling, transplanting trajectory and posture, mechanical structure, and so on.By appling fuzzy mathematics theory, the appropriate subordinate functions were used todescribe requirements of each objective, which made the fuzzy objectives numerical. Then, tennumerical optimization objectives of the transplanting mechanism for rice pot-seedling werebuilt.3) The parameter modification guiding optimization method was applied to optimizeparameters of the mechanism. Parameter optimization software of the mechanism was developedindependently based on the visualized platform of Visual Basic. This parameter optimizationsoftware has received registration copyright (registration number:2014SR102877). By using thisself-developed software, a set of parameters meeting the requirements of transplanting trajectoryand posture was obtained. The value of parameters are as follows: a=24.482mm, k=0.991mm,η=283°,λ=5°,0=29°, φ0=70°, S=153mm.4) Aiming to solve the problems occurred in the seedling picking-up test conducted byauthor’s research group before, existing shortages of designing on the structure of origintransplanting mechanism was analyzed, then, rice pot-seedling transplanting mechanism wasredesigned. The main design work is to add seedling pushing device and redesign cammechanism in the transplanting arm with analytical method.5) Based on the optimized structure parameters and the improvement design, the wholestructure of rice pot-seedlings transplanting mechanism was designed, then its3D model wasestablished by UG7.5and imported into ADAMS to establish its virtual prototype. Virtualprototype test was carried out for movement simulation. Simulation motion trajectory and time ofseedling pick-up were obtained. Compared with results of the improved mechanism and theprimary one, correctness of optimization method and results of the mechanism and correctmessand effectiveness of improvement design of cam mechanism were verified.6) After physical prototype was developed, high-speed digital video camera and imageprocessing technology were used to complete kinematics test. Through this test, transplantingtrajectory and gesture of the mechanism were achieved and compared with the results of theoretical analysis. The basic consistency of two results shows that the designed mechanism canmeet transplanting requirements and the optimization design method and results are also correct,7) The seeding pick-ip tests of transplanting mechanism under three different conditionswere carried out. The conditions are different rotary speed, different cam mechanism and with orwithout seeding pishing device. Through tests, the influence on the seedling pick-up success rateunder different rotary speed, seedling pick-up success rate of mechanism with improved orunimproved cam mechanism, and seedling pushing effect of mechanism with or without seedlingpushing device were achieved to verify improvement effct and work performance oftransplanting mechanism, which could prove the feasibility for the mechanism being applied tothe actual transplanter.