圆形多轴多旋翼电动无人机辅助授粉作业参数优选

圆形多轴多旋翼无人直升机与单轴单旋翼无人直升机相比,结构上有很大差异,因而其旋翼所产生气流到达作物冠层后形成的风场参数亦有所不同。该文采用3种圆形多轴多旋翼无人直升机,根据正交试验设计法设计了3因素(飞行高度、飞行速度以及飞机与负载质量)3水平的正交试验,通过考察平行于飞行方向(X)、垂直于飞行方向(Y)、垂直地面(Z)3个方向上的峰值风速、Y向风场宽度(越宽越好)、动力电池的压降(放电越慢越好)3个指标,对该机型用于水稻制种辅助授粉的田间作业参数进行优选,试验结果分析表明:圆形多轴多旋翼无人直升机在水稻冠层形成的X向风场宽度明显大于Y向的风场宽度;有别于单旋翼无人直升机,圆形多轴多旋翼无人直升机X向风场只有1个峰值风速中心,Y向风场存在2个峰值风速中心,这一现象主要由飞行器多个旋翼的侧向气流叠加形成,相互之间存在干扰,而且也影响了Y向风场的有效宽度。在实际应用中,对于能实现GPS自主导航飞行的机型,应根据作业的便利程度尽量利用X向的风力,更有益于辅助授粉作业;而对于未采用GPS自主导航飞行的机型,为便于飞控手对飞机位置的判断与姿态操控而必须沿父本行方向进行飞行作业时(即利用Y向风力),应充分考虑垂直于飞行方向风场宽度较窄的实际情况,通过降低作业效率来弥补。圆形多轴多旋翼无人直升机在水稻冠层所形成风场的峰值风速主要受飞机的飞行速度、飞机与负载质量、飞行高度影响。结合有效风场宽度及电池电量消耗程度来考量,3种主要因素的主次排序及其较优水平依次为飞行速度1.30 m/s、飞机与负载质量18.85 kg和飞行高度2.40 m。该结果可为其他圆形多轴多旋翼无人直升机用于水稻制种辅助授粉的田间作业参数设置提供参考,而且也可为制定基于农用无人直升机的水稻制种辅助授粉作业技术规范提供依据。

Optimization of operation parameters for supplementary pollination in hybrid rice breeding using round multi-axis multi-rotor electric unmanned helicopter

Abstract: Compare with uniaxial single-rotor electric unmanned helicopter (USREUH), the structure of round multi-axis multi-rotor electric unmanned helicopter (RMMEUH) is very different to USREUH, and thus its wind field parameters on rice canopy which formed by rotor airflow are also different. To explore the optimization parameters when the RMMEUH conducted supplementary pollination, in this study orthogonal tests of three factors (including flight operating load, altitude and speed) and three levels were carried out to measure the wind field. The tested RMMEUHs include two 8-rotors electric unmanned helicopters and an 18-rotors electric unmanned helicopter.The measured wind directions included parallel to the direction of flight heading (X), perpendicular to the direction of flight heading (Y), and the vertical direction (Z). The battery's voltage drop was also measured at each takeoff and landing of RMMEUH to estimate its economy. A wireless wind speed sensor network measurement system (WWSSN) was used to measure the wind field parameters of the RMMEUH. The WWSSN consists of several wireless wind speed sensors (WWSS, numbered 1#-10#), a flight global position system (FGPS), and an intelligent control focus node (ICFN). The WWSS was used to measure the wind field parameters on rice canopy. FGPS was used to measure the pose information of the RMMEUHs when they fly over the rice canopy. ICFN was used to control and record the wind field parameters. 1#-9# WWSSs were used to measure the wind field parameters which mixed with natural wind and RMMEUH produced wind. And another one, 10#, was set up far from 9#, was mainly used to measure the natural wind speed. In order to reduce the effect from natural wind speed, treatment rules about natural wind speed were adopted before wind field data analysis. The test results showed that: the width of the wind field at X direction was significantly wider than Y direction; Unlike USREUH, there were only one peak wind speed center at X direction of RMMEUH, while two at Y direction, this phenomena might be caused by the superimposition of multiple rotors of RMMEUH, and the lateral flow of the aircraft was also one of the interferences, as a result, narrowed the width of the wind field at Y direction. Comprehensively considered about the width of wind field and battery electricity consumption, the order of the three influence factors was flight speed, takeoff weight, and flight height. Flight speed of 1.30m/s, takeoff weight of 18.85 kg, and flight height of 2.40 m were suggested as the optimization of the operation parameters for supplementary pollination in hybrid rice breeding using RMMEUH. The results provide references to develop a series of specifications of supplementary pollination in hybrid rice breeding using unmanned helicopter.