Research On Multidisciplinary Design Optimization Of Transplanting Mechanism With Planetary Elliptic Gears Based On Approximation Model

Transplanting mechanism is the core component in a rice transplanter whose function is to adopt a certain number of seedlings from a seedling tray and insert it into the soil while its performance which primarily depends on the configuration of structural parameters determines the planting quality.Transplanting mechanism with good structural parameters during field work can make mild orthostatic seedlings without hurting them and has low vibration.Therefore,parameter optimization of the rice transplanter is one of the key issues during design of the transplanting mechanism.The traditional methods of design optimization are increasingly difficult to meet the requirements of the overall design because of the complexity of the transplanting mechanism.In addition,kinematic,dynamic and structural mechanic properties have greater impact on its performance while there are mutual contradictions and influence among these disciplines.Multidisciplinary design optimization(MDO)method is used to organize the variables and the objectives effectively to achieve interdisciplinary association,communications and decoupling which can improve overall performance of the transplanting mechanism.In this paper,the research on multidisciplinary design optimization of transplanting mechanism with planetary elliptic gears based on approximation model was carried out aiming at problems such as multi-objective,strong coupling,nonlinear and fuzziness during the optimization process.MDO strategies were determined and the system was separated into three disciplines.In addition,MDO mathematical model for transplanting mechanism and the approximation model which saved computation time between system-level variables and subsystem-level objectives were established.Integrated platform for MDO of transplanting mechanism with planetary elliptic gears was built eventually.The detail conclusions are as follows:(1)Optimization method and optimization algorithm were assured for the MDO of transplanting mechanism with planetary elliptic gears after analyzing and comparing the commonly used MDO methods and algorithms.(2)The optimal target,design variables and constraints of each discipline were determined by analyzing for the transplanting mechanism.Then on this basis,MDO mathematical model of the transplanting mechanism based on collaborative optimization frame was established.(3)The DOE(Design of experiment)method to construct sample points for the approximation models was proposed.Furthermore,the approximation model type was assured whose accuracy met design requirements by assessment.(4)Based on collaborative frame,hybrid optimization algorithm and Kriging model,the integrated platform for MDO of transplanting mechanism with planetary elliptic gears was established by using Isightv5.7 software and the results were analyzed which achieved the desired effect.