基于精确多位姿解析的水稻钵苗移栽机构研究

Transplanting Mechanism of Rice Seedling Based on Precise Multi-position Analysis

摘要:

由于现有的贝塞尔齿轮行星轮系水稻钵苗移栽机构移栽过程中存在移栽臂甩泥现象，通过分析其作业轨迹探寻问题引起的原因，并基于精确多位姿运动解析理论进行移栽轨迹改善与机构参数求解。根据移栽过程中夹苗开始、夹苗结束和推苗3个动作的位置和姿态要求，确定约束移栽轨迹的3个精确位姿点。将轮系式移栽机构的设计过程分解为开链2R机构（由去除输出齿轮以外的所有齿轮得到）的运动综合和不等速传动比设计两个阶段。基于给定连架杆长度三位置运动生成机构综合方法，建立开链2R机构圆心点（轮系机构的输入点）和圆点（轮系机构的输出点）曲线方程，并求解获得不同杆长时对应圆点和圆心点的位置曲线；拟合带关键点位置信息的期望轨迹，求解基于此轨迹的开链2R机构角位移并分析其单调性，实现机构总传动比的求解与分配；设计七齿轮行星轮系水稻钵苗移栽机构并进行仿真与台架试验。通过与原机构的理论与试验结果对比分析得出，新机构的移栽轨迹回程段与地面的夹角增加到90°，环扣高度增加到68mm，推苗点与箱体回转中心最低点的距离增加到21mm，改善了水稻钵苗的移栽质量。

关键词:水稻;钵苗;移栽机构;精确多位姿解析

Abstract:

Due to the phenomenon of transplanting arm mud-dumping in the process of transplanting in the existing Bezier gear planetary gear system rice seedling transplanting mechanism, the causes of the problems caused by the operation trajectory were analyzed, and the transplanting trajectory improvement and solution of mechanism parameters were carried out based on the analytical theory of precise multi-position motion. According to the position and attitude requirements of the three actions of the beginning, the end and the pushing of seedlings during transplanting process, the three precise pose points of the constrained transplanting trajectory were determined. The design process of the gear-train transplanting mechanism was divided into two stages: the motion synthesis of the open-chain 2R mechanism (obtained by removing all gears except the output gear) and the design of the unequal speed transmission ratio. Based on the synthesis method of three-position motion generation mechanism with given link length, the curve equations of the center point (the input point of gear train mechanism) and the circle point (the output point of gear train mechanism) of the open chain 2R mechanism were established and the position curves corresponding to the circle point and the center point were obtained when the length of the rod was different. The desired trajectory with key point position information was fitted. The angular displacement of the open-chain 2R mechanism based on the trajectory was solved and its monotonicity was analyzed, solution and distribution of the total transmission ratio of the mechanism were realized. Transplanting mechanism of rice seedling with seven-gear planetary wheel was designed, and the simulation and bench test were carried out. Through the comparison with the theoretical and experimental results of the original mechanism, it was found that the angle between the backhaul section of the transplanting path of the new mechanism and the ground was increased to 90°, the height of the buckle was increased to 68mm, and the distance between the seedling point and the lowest point of the rotation center of the box was increased to 21mm. The transplanting quality of rice seedling was improved.

Key words:rice;pot seedling;transplanting mechanism;accurate multi-pose analysis