油菜成条飞播装置设计与试验

为解决常见地面播种机器无法进入或进入经济效益不高场景下的油菜播种问题,基于极飞P20商用植保无人机平台,设计一种基于电驱离心条播式排种器的无人机油菜飞播装置,以实现类似地面机器条播而非撒播的效果。首先对已有倒置锥筒离心式排种器进行改进,设计上凸锥筒离心式排种器结构,并确定排种盘和排种口等关键部件的结构参数。在分析该款无人机下洗气流场分布规律的基础上,提出了一种与该离心排种器配合使用的辅助导种装置。排种性能台架试验表明,当排种转速在40~220 r/min范围逐渐增加时,单位时间总排量呈现先持续增加后趋于稳定,且在排种转速为190 r/min时达到最大单位时间总排量179.65 g/min,可满足无人机作业速度5 m/s所需的排量要求;各行排量一致性变异系数和总排量稳定性变异系数先减小后增大,分别分布在4.5%~12.6%和0.7%~6.2%范围内;种子籽粒破损率随排种转速增大逐渐增大,但均在2%以内。样机场地测试试验表明,导种装置高度在1.5~2.5 m范围内变化时,成条指数与其没有显著相关性(P=0.0769>0.05),且成条宽度不到设定行距的1/4。进一步的田间试验结果显示,成条指数为35.0%,播种均匀性变异系数为19.26%,满足油菜条播农艺技术要求。

Design and experiment of a device for rapeseed strip aerial seeding

UAV can realize track planning and automatic navigation flight due to its small size and flexible operation performance. It has been widely used in the agricultural field for its advantages of high obstacle crossing performance, stability and operation efficiency comparing to ground machines. At present, most UAV based aerial seeding devices use core parts like horizontal centrifugal disc or outer groove wheel to scatter seeds, fertilizers and other materials in the air. Due to the high seeding height and the disturbance of UAV rotor air flow, the randomness of material particles after landing is very large, and they are generally scattered on the whole plane. Although it has high seeding efficiency, it belongs to a relatively extensive seeding mode for that it is not easy to control the seed uniformity affected by many factors. In view of the above problems, a kind of rape aerial seeding device based on an electrically driven centrifugal seeding meter was designed and tested for XAG P20 which is a commercial crop protection UAV. The aerial seeding device can seed in lines instead of wide area, and is more conducive to improving the uniformity of seedlings and the convenience of field management during crop growth. In this paper, we first improved the design of the concave cone centrifugal seed metering device, and determined the structural parameters of the key components such as seed metering tray and seed metering port. Then, based on ANSYS Fluent simulation software, the distribution of downwash air flow field of the XAG P20 drone was analyzed. An auxiliary seed guiding device used in combination with the centrifugal seed metering device was proposed and built. Three experiments including the seed metering performance test, the prototype test and the field test are carried out to analyze and study the functions of the aerial seeding device. The results show that the total seeding quantity per unit time increases when the seeding rotation speed increases from 40 to 190 r/min, and the maximum total seeding quantity reaches 179.65 g/min at 190 r/min, which can meet the requirements of 0-5 m/s operation speed of the drone; the variation coefficient of consistency and stability of apiece row seeding quantity decreases first and then increases, which are distributed in the range of 4.5%-12.6% and 0.7%-6.2% respectively. The damage rate of seeds increased gradually, all of which are within 2%. The prototype test shows that when the height of the seed guiding device is in the range from 1.5 to 2.5 m, the width of the seed strips is less than 1/4 of the row spacing, and the striping index of the seed has no significant correlation with it. However, considering the operational risk and convenience of the personnel in the actual operation process, the height of 2 m is selected as the appropriate height of the seed guiding device. Under that condition, the field experiment results show that: the strip index is 35.0%, the variation coefficient of sowing uniformity is 19.26%, which can meet the technical requirements of rape drilling.