基于平稳有序运移机理的高速玉米精量播种机种子精确投送方法研究

High speed and efficiency has become the development trend for corn precision planter, but the sowing quality will decrease as sowing speed increase which will lead to a reduction of corn yield. It is difficult to ensure the uniformity of seed distribution only by means of improving accuracy of seed-metering device, the key to solve this problem is to reduce and to eliminate the deviations of seed in furrow between actual position and theoretical position resulted by collision and bounce during delivery from seed-metering device to seed bed. Aiming at the problem, one method of seed precision transportation and delivery is proposed by which the function could be realized of actively grabbing seeds, transporting seeds and releasing seeds in zero-speed accurately and regularly, this method can effectively reduce the coefficient of variation of seed in seed bed due to the high sowing speed and high release height. Kinematics and dynamics model for corn seed will be built to analyze the seed movement path, and to reveal the smooth and order movement mechanism of seed in the seed precision transportation and delivery system under the circumstance of high-speed sowing combined with numerical simulation and dynamic analysis. Effect of factors on sowing performance will be clarified in the seed precision transportation and delivery system, including degree of influence, influence mechanism and master-subordinate relationship, and the relationship will be quantified among key parameters and uniformity of seed spacing for every part by experimental research. In addition, control method will be established which will contribute to improving stability and reliability of seed precision transportation and delivery system, and a seed precision transportation and delivery mechanism will be developed which will provide a basic theoretical model and technology in use for the development of agricultural equipment to the direction of high-speed and accuracy.

高速高效是玉米精量播种机的发展方向。但随着作业速度的提高，播种粒距均匀性会显著下降。单纯依靠提升排种器精度已难以保证粒距均匀，需要解决高速作业时种子下落过程中与导种管壁碰撞及落地弹跳造成的异位加剧的问题。为此本课题提出一种从排种器主动取种、精确运种、实时零速投种的种子精确投送方法，消除种子因碰撞造成的间距偏差，缓解种子落入种床时的跳动，最大限度地提升高速作业播种粒距均匀性。通过建立玉米种子运动学和动力学模型，结合数值模拟和动态仿真，分析种子运动轨迹和受力变化规律，揭示高速作业时种子在投种系统中“平稳有序”的运移机理；通过试验研究，明确投种系统各因素变化对最终投种效果的影响程度、影响机制和主次关系，量化各环节关键参数与播种粒距均匀性的相互关系；研究提升投种系统稳定性和可靠性的控制策略；研发一种适于高速玉米精量播种机的种子精确投送机构，为玉米精量播种机的高速化精准化提供理论支撑和创新实用技术。

项目针对高速作业时种子从排种器下落后在输送过程中与导种管壁碰撞及落地时弹跳造成的播种粒距均匀性急剧变差的问题，提出了一种精准取种、有序运移、平稳投种的种子投送新方法，探明了形成平稳有序种子流的运移机理，明确了在取种、输送、投种环节中关键因素变化对播种粒距均匀性的影响机制，提出了提升种子投送系统作业性能的控制策略，创制了一种能够实现种子平稳有序运移的精准投送装置，消除了种子在投送过程中因碰撞造成的粒距偏差，缓解了种子落入种床时的无序弹跳，显著提升了高速作业时的播种粒距均匀性。具体内容如下：.建立了玉米种子在投送过程各环节（取种、输送、投种）的运动学模型，通过理论计算初步确定了种子投送装置关键结构参数；建立了玉米种子颗粒体模型，通过EDEM对取种和投种过程进行了仿真分析，得出了种子在投送过程各环节的运动轨迹；通过分析种子运动轨迹变化规律，探明了种子在投送系统中形成平稳有序种子流的运移机理，同时优化了投送装置关键结构参数。.开展了种子投送装置关键参数（包括落种高度、落种水平距离、拨指间距、投种板形状和投种角）对播种粒距均匀性的影响研究，明确了各关键参数对播种粒距均匀性的影响机制和主次关系；以精准取种和种子平稳着床为目标，提出了提升种子投送系统作业性能的控制策略和最优参数组合。.开发了种子精确投送装置及其控制系统，开展了实验室台架试验和田间试验，试验结果表明，在高速13.1km/h播种作业条件下，与导种管种子输送方式相比，种子投送装置的粒距合格指数提高了12.3%，粒距变异系数降低了10.5%，种子投送装置显著提高了播种粒距均匀性。.本研究为高速精量播种提供了一种提升粒距均匀性的新方法。项目执行期间，共发表SCI、EI期刊论文15篇，其中SCI论文7篇，第一标注论文6篇；申报国家发明专利7项，其中已授权3项；培养博士生3名，硕士生3名；参加国内外学术会议4次。全面完成了项目各项研究任务和目标。