无人机机载喷雾系统喷雾特性及影响因素的研究

发布时间：2018-12-31 07:58

【摘要】：农业精准化趋势下,植保无人机凭借其超强适应能力、高效作业能力、节省劳动力、节约资源和保护环境等诸多优点,在国内农业航空领域具有良好的发展前景。由于植保无人机作业环境复杂多变,导致农田试验条件不易控制,试验结果不能作为植保无人机喷洒作业的具体参考标准。针对以上田间喷洒试验的环境多变性,将多旋翼植保无人机仿真平台及机载喷洒系统搭建起来用于科学研究,并编写了用于雾滴沉积的图像处理分析程序"DropletAnalysis"。在总结国内外植保无人机研究进展之后,结合水敏纸的雾滴沉积检测和图像处理程序"DropletAnalysis"、红外热成像等技术手段,研究了低空不同作业高度、飞行速度以及茶树植株不同沉积层上雾滴沉积特性的变化规律。具体研究内容和成果如下:(1)首先确定无人机仿真平台喷洒系统在不同作业高度下产生的有效喷幅宽度,在有效喷幅宽度范围内,探究发现:在1.0 m、1.2 m、1.4 m作业高度的梯度变化下,有效喷幅宽度分别为2.57 m、2.94 m和3.21m,茶树植株上雾滴沉积覆盖率Coverage呈现出随作业高度升高而下降的变化规律,其在1.0m、1.2 m、1.4m作业高度下,雾滴覆盖率分别为17%、11%和10%。(2)排除自然风的干扰,无人机仿真平台通过对飞行速度的调控,对不同飞行速度下茶树植株上沉积的雾滴质量评价指标进行探究。结果发现:在0.3 m/s、0.5m/s、0.7m/s、0.9m/s、1.0m/s飞行速度下,雾滴沉积密度Density值、雾滴沉积覆盖率Coverage以及雾滴粒径算术平均值D0都随无人机飞行速度的增加而降低,而在0.3 m/s-1.0m/s飞行速度范围内,反映雾滴粒径分布均匀性的雾滴粒径变异系数CV值分别为0.891、0.979、1.026、1.311和1.243,随飞行速度的增加而增大,导致喷洒出来的雾滴粒径分布均匀性变差。红外热成像仪在航空喷洒试验中,通过对喷洒前、后作物叶片表面温度变化率的记录分析,将叶片表面温度变化率与水敏纸检测结果进行对照,发现规律一致。因此,说明热红外成像技术可以有效反映出各作业参数变化后雾滴沉积覆盖率的变化。(3)本研究选用茶树高度约为0.6m,茶树植株不同沉积层对喷洒雾滴沉积量的接受概率存在差异,相应试验结果表明:植保无人机喷洒作业过程中,作物植株沉积层按照自上而下的顺序,植株叶片表面的雾滴沉积覆盖率Coverage会逐渐降低,飞行速度为0.3 m/s时,五棵茶树上、中、下沉积层上平均雾滴沉积覆盖率依次为33.79%30.47%17.21%;飞行速度为0.5 m/s时,茶树上、中、下沉积层上平均雾滴沉积覆盖率依此为26.90%14.14%8.31%;飞行速度为0.7 m/s时,茶树上、中、下沉积层上平均雾滴沉积覆盖率依此为18.89%16.11%13.62%。。
[Abstract]:Under the trend of agricultural precision, plant protection UAVs have a good prospect in the field of agricultural aviation because of their excellent adaptability, high efficiency, labor saving, resource saving and environment protection. Because the environment of plant protection UAV is complex and changeable, it is difficult to control the field test conditions, so the test results can not be used as a specific reference standard for plant protection UAV spraying operation. In view of the environmental variability of the above field spraying experiments, the simulation platform of multi-rotor plant protection UAV and the airborne spraying system were set up for scientific research, and the image processing and analysis program "DropletAnalysis" for droplet deposition was developed. After summing up the research progress of plant protection UAV at home and abroad, combined with the droplet deposition detection of water sensitive paper and image processing program "DropletAnalysis", infrared thermal imaging and other technical means, the different operating heights at low altitude were studied. The variation of the velocity of flight and the deposition characteristics of fog droplets on different sediment layers of tea plants. The specific research contents and results are as follows: (1) at first, the effective width of spraying amplitude produced by the UAV simulation platform spraying system at different operating heights is determined. In the range of effective spray width, it is found that the width is 1.0 m ~ (1.2 m). Under the gradient of 1.4 m operating height, the width of effective spraying amplitude was 2.57 mm 2.94 m and 3.21 m, respectively. The droplet deposition coverage (Coverage) of tea plant decreased with the increase of operating height, which was 1.0 m. At the operating altitude of 1.2 m ~ 1.4 m, the droplet coverage was 17% and 10%, respectively. (2) eliminating the interference of natural wind, the UAV simulation platform controlled the flight speed. The quality evaluation indexes of fog droplets deposited on tea plants at different flying speeds were studied. The results show that at the speed of 0. 3 m / s 0. 5 m / s 0. 7 m / s 0. 9 m / s / s 1.0 m / s, the droplet deposition density Density value, The droplet deposition coverage Coverage and the arithmetic average of droplet diameter D0 decreased with the increase of UAV velocity, but in the range of 0.3 m/s-1.0m/s, The coefficient of variation (CV) of droplet size distribution, which reflects the uniformity of droplet size distribution, is 0.891U 0.979U 1.0261.311 and 1.243, respectively, which increases with the increase of flying velocity, resulting in the uniformity of droplet size distribution becoming worse. In the aerial spraying test of infrared thermal imager, the change rate of leaf surface temperature before and after spraying was recorded and analyzed, the change rate of leaf surface temperature was compared with the test result of water sensitive paper, and the rule was found to be consistent. Therefore, the thermal infrared imaging technique can effectively reflect the change of droplet deposition coverage after the change of operation parameters. (3) the tea tree height is about 0.6 m in this study. The acceptance probability of spray droplet deposition was different among different sediment layers of tea plant. The results showed that during the spraying process of plant protection UAV, the sediment layer of plant was in the order of top-down. The droplet deposition coverage (Coverage) on the leaf surface of the plant decreased gradually. When the flying velocity was 0.3 m / s, the average droplet deposition coverage on the five tea trees, middle and lower layers was 33.790.47 and 21, respectively. When the flight velocity is 0.5 m / s, the average fog deposition coverage on the top, middle and lower layers of tea trees is 26.90 ~ 8.31; When the flying speed is 0.7 m / s, the average droplet deposition coverage on the tea tree is 18.89 ~ 1.11 ~ (.62) 路s ~ (-1) on the top, middle, and lower layers of tea.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S252.3

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