非圆齿轮-连杆一体式水稻钵苗膜上移栽机构动力学优化与试验

Dynamic Analysis Optimization and Test of Integrated Non-circular Gear-linkage Rice Pot Seedling Transplanting Mechanism for Film-mulched Paddy Fields

摘要:

针对非圆齿轮-连杆一体式行星轮系水稻钵苗膜上移栽机构因外侧挂载组合破膜挖穴四杆机构导致整体质量增大、质心偏置及驱动转矩突变问题，本文基于第二类拉格朗日方程开展一体式非圆齿轮行星轮系机构动力学建模分析与优化设计研究。明确组合轮系机构动力学研究系统，完成独立运动自由度确立与行星架转角广义坐标选取，通过系统总动能与总势能计算，实现拉格朗日函数与机构刚体动力学方程构建;通过数值求解解析驱动转矩极值特性与突变规律，明确组合四杆机构对动力学性能的显著影响及牙嵌结构疲劳风险;针对机构质心偏置与转动惯量增大耦合矛盾，基于理论模型开发Matlab动力学优化模块，并以最大驱动转矩和系统转动惯量为评价指标，提出移栽臂部件反向布置配重策略，实现配重参数多目标寻优。优化结果表明，当配重质量为0.13367 kg时，机构最大驱动转矩降至623.0304 N·mm，优化率达17.252%，实现质心近回转中心布置同时有效抑制转动惯量增大的负面影响。最终，通过动力学试验台架开展物理验证模型准确性，并通过优化选用0.1 kg配重测试，实测机构最大、最小驱动转矩分别优化13.38%、10.68%，驱动转矩整体波动显著减小，有效缓解了动力学性能劣化问题，提升了机构作业稳定性与可靠性。

Abstract:

Aiming at the problem of overall mass increase, centroid offset and driving torque mutation caused by the four-bar mechanism of the non-circular gear-connecting rod integrated planetary gear train transplanting mechanism on the film of rice pot seedling, the dynamic modeling analysis and optimization design of the integrated non-circular gear planetary gear train mechanism was studied based on the second Lagrange equation. Firstly, the dynamic research system of the combined gear train mechanism was defined, and the establishment of its independent motion freedom and the selection of the generalized coordinates of the planet carrier rotation angle were completed. Through the calculation of the total kinetic energy and total potential energy of the system, the Lagrange function and the rigid body dynamics equation of the mechanism were realized. Then, the extreme value characteristics and mutation rules of the driving torque were analyzed by numerical solution, and the significant influence of the combined four-bar on the dynamic performance and the fatigue risk of the embedded structure were clarified. Aiming at the coupling contradiction between the center of mass offset and the increase of the moment of inertia of the mechanism, the Matlab dynamics optimization module was developed based on the theoretical model. Taking the maximum driving torque and the moment of inertia of the system as the evaluation indexes, the counterweight strategy of the reverse arrangement of the transplanting arm components was proposed to realize the multi-objective optimization of the counterweight parameters. The optimization results showed that when the counterweight mass was 0.13367 kg, the maximum driving torque of the mechanism was reduced to 623.0304 N·mm, and the optimization ratio was 17.252%. The arrangement of the center of mass near the center of rotation was realized and the negative effect of the increase of the moment of inertia was effectively suppressed. Finally, the accuracy of the physical verification model was carried out through the dynamic test bench, and the maximum and minimum driving torques of the measured mechanism were optimized by 13.38% and 10.68% respectively by optimizing the selection of 0.1 kg counterweight test. The overall fluctuation of the driving torque was significantly reduced, which effectively alleviated the problem of dynamic performance degradation and improved the stability and reliability of the mechanism operation.