基于动载荷状态的植保无人机作业参数动态模型及多模态作业方法研究

The medicine liquid is the task load of plant protection UAV in aerial spraying application and will being decrease continuously, which determines that the task load is a continuously dynamic parameters when the medicine liquid dropping gradually under the action of rotor wind field. The change of load will inevitably lead to the change of lift generated by the rotor of UAV, which will change the distribution of wind field and the effect of droplet deposition. This conclusion has also been confirmed by the project applicant's test.Aiming at the problems of the lack of continuity research on the mechanism of droplet deposition and the inability to guarantee the operation effect by single operation mode for plant protection UAV, the applicant focused on the research on the variation of rotor wind field caused by dynamic load of plant protection UAV based on the previous research on the operational parameters and the influence mechanism of rotor wind field on droplet deposition distribution. Through the real-time acquisition and the spatial-temporal registration for various parameters, the distribution characteristics of rotor wind field under dynamic load status are studied, the dynamic model of operation parameters and the follow-up model of effective spraying width based on dynamic load status are built, and a multi-modal operation method for plant protection UAV which can regulate the operating parameters and the track spacing based on the dynamic load status are proposed. The study can provide a theoretical basis for the development of the precision spraying operation mode of plant protection UAV directly applied to the spraying operation practice, and will improve the effect of aerial spraying of plant protection UAV.

药液作为植保无人机航空施药作业的任务载荷，随着药液雾滴在旋翼风场作用下逐渐沉降，药液的持续减少决定了载荷是一个连续动态变化的参数。载荷的改变必然导致无人机旋翼产生的升力发生改变，从而改变旋翼风场分布和雾滴沉积效果。这一结论也得到了申请人的试验证实。针对植保无人机存在雾滴沉积机理的连续性研究不足，植保无人机作业模式单一、无法保证作业效果等问题，申请人结合前期关于植保无人机作业参数及旋翼风场对雾滴沉积分布影响机理的研究基础，重点围绕植保无人机动载荷引起的旋翼风场分布变化问题开展相关研究；通过对各参数的实时获取及时空配准，研究动载荷状态下旋翼风场分布特性，构建基于动载荷状态的作业参数动态模型和有效喷幅随动模型，提出基于动载荷状态下作业参数和航迹间距进行调控的植保无人机多模态作业方法，为开发直接应用于喷施作业实践的植保无人机精准喷施作业模式提供理论依据，提升植保无人机田间作业效果。

植保无人机航空喷施作为减少农药用量、降低农药残留和提升农药防效的有力手段，具有广阔的应用前景和市场。然而，在整个喷施作业过程中，受药液载荷持续减少的影响，植保无人机旋翼风场分布和雾滴沉积效果存在差异。因此，探明由药液载荷变化引起的旋翼风场及雾滴沉积变化机理对保证植保无人机航空喷施作业效果具有积极意义。基于研究任务，重点围绕植保无人机动载荷引起的旋翼风场分布变化问题，主要开展了如下研究：.（1）基于无人机动力系统性能测试平台，以旋翼转速和升力为指标，以动力系统油门占空比为变量，结合不同动力系统对应的机型，匹配旋翼产生的升力与药箱有效载荷，构建了植保无人机药箱满载到空载过程中有效载荷与旋翼转速之间的关系模型。（2）结合多旋翼植保无人机连续作业过程中药箱有效载荷的变化范围，通过改变旋翼转速来对应作业过程中药箱有效载荷的变化，研究了旋翼植保无人机连续作业过程中药箱有效载荷的不断变化对旋翼风场的影响。（3）结合多旋翼植保无人机作业过程中药箱有效载荷的变化情况，调整动力系统旋翼转速实现对旋翼风场的控制，通过 PIV 技术获取不同旋翼风场作用下的雾滴运动参数，研究了多旋翼植保无人机旋翼风场对雾滴沉积运动特性的影响。（4）以搭配液力式喷头和离心式喷头的多旋翼植保无人机，改变药箱有效载荷进行田间喷施试验，通过采集不同位置点旋翼风场参数和雾滴沉积量，探究了不同有效载荷作业状态下多旋翼植保无人机旋翼风场分布特性和雾滴沉积分布特性。（5）以最优雾滴沉积效果作为旋翼风场分布模型的约束变量，求解出植保无人机较优的飞行作业参数，通过田间试验构建了植保无人机在最优作业参数下有效喷幅与药液载荷的变化模型，并结合航迹规划算法形成了一种基于动载荷状态的植保无人机变间距喷施的作业方法，为开发直接应用于喷施作业实践的植保无人机精准喷施作业模式提供依据，提升植保无人机田间作业效果。