多旋翼植保无人飞机施药研究进展及展望

Research progress and prospects of spraying of multi-rotor plant protection UAV

多旋翼植保无人飞机有良好的地形适应性及超低空喷雾能力,是高效植保装备的重要发展方向之一,但飞行作业条件下风场、雾滴、作物耦合机理尚不明晰,成为制约沉积分布品质提高的瓶颈。为剖析植保无人飞机施药作业各要素关联研究不足、沉积机理不够清晰等问题。以雾滴的发生、沉降、沉积及飘移全过程为主线,基于学者们的研究论述了喷嘴雾化药液、风场-雾滴交互作用以及风场-雾滴-冠层耦合作用的研究现状,分别从喷嘴雾化对施药效果的影响、旋翼植保无人飞机悬停和飞行条件下的风场分布规律、飞行施药条件下雾滴在冠层内沉积飘移分布规律几个方面展开分析。基于以上论述,梳理了国内外航空施药技术的应用背景、研究进展、经验模型。指出了当前多旋翼植保无人飞机施药过程中一些亟需解决的问题,针对喷嘴选型(液力式喷嘴、离心式喷嘴等)及工作参数(压力、转速、角度、流量等)、无人机飞行参数(飞行速度、旋翼转速等)、农药特性(密度、黏度、表面张力等)及药液雾滴群的初始参数(粒径分布、初始速度)等各因素之间的匹配对应关系尚不明晰的问题,提出了重点建立多旋翼植保无人飞机施药作业喷嘴选型决策专家系统的建议;针对飞行组合风场(旋翼下洗气流、迎风气流、自然横风),农药药液雾滴(雾化后的物性参数),作物冠层(作物典型生长周期的茎、枝、叶)、田间环境(温、湿度),作业参数(飞行速度、高度)等因素的耦合作用,提出基于施药沉积效果进行科学假设,建立组合风场-药液雾滴-作物冠层的三相耦合模型的建议。最后,对未来多旋翼植保无人飞机施药技术的发展进行了展望。

Multi-rotor plant protection Unmanned Aerial Vehicles(UAV)has good terrain adapt ability and efficient ultra-low altitude spraying capacity,which is one of the important development directions of efficient plant protection equipment.However,the interaction mechanisms of wind field,droplet and crop under flight operation are unclear,which has become the bottleneck restricting the improvement of the deposition distribution quality.This study aims to analyze the problems such as insufficient correlation studies and unclear deposition mechanism of various elements in the spray application of plant protection UAV.This study focuses on the whole process of generation,settlement,deposition and drift of pesticide droplet.And based on the previous research,this paper discussed the research status of spray pesticide liquid with nozzle,the interaction between the wind field and the droplet,as well as the coupling of the wind field,the droplet and the canopy.The effect of nozzle atomization on spray effect,the distribution law of wind field under hover and flight conditions of plant protection UAV,the distribution law of droplets deposition and drift in canopy under flight spary conditions were analyzed separately.Based on the above discussion,the application background,research progress and empirical models of aviation application technology at home and abroad were reviewed.Some problems that need to be solved in the spary application process of multi-rotor plant protection UAV were identified.The matching and relationships between nozzle selection(hydraulic nozzle,centrifugal nozzle,etc.)and working parameters(pressure,speed,Angle,flow,etc.),UAV flight parameters(flight speed,rotor rotation speed,etc.),pesticide characteristics(density,viscosity,surface tension,etc.)and initial parameters of liquid droplets(particle size distribution,initial velocity)are not clear,a suggestion was proposed to establish a nozzle selection decision-making expert system for multi-rotor plant protection UAV spray scene.In terms of the coupling effect of flight combination wind field(rotor downwash flow,upwind flow,natural cross wind),pesticide liquid droplets(physical property parameters after atomization),crop canopy(Stems,branches,leaves of a typical growth cycle of a crop),field environment(temperature,humidity)and operation parameters(flight speed and altitude),a proposal was put forward to establish a three-phase coupling model of combined wind field-pesticide liquid droplet-crop canopy based on scientific assumptions of deposition effects.Finally,the future development of application technology of Multi-rotor plant protection UAV was prospected.