无人油动力直升机用于水稻制种辅助授粉的田间风场测量

无人驾驶直升机具有机动灵活、不需要专用机场等特点,目前已在农业航空植保中得到应用。杂交水稻制种中,利用无人直升飞机飞行时其旋翼产生的风力能使父本花粉传播更远,可扩大父本和母本相间种植的宽度,实现父本和母本的机械化耕种和收割,从而实现制种全程机械化。杂交稻制种辅助授粉的效果(母本异交结实率)、作业效率及经济效益与无人直升机飞行时产生的风速、风向和风场宽度等参数密切相关,但迄今尚不明确。该文采用风场无线传感器网络测量系统组成三向风速测量线阵和单向风速面阵在水稻田里对无人油动单旋翼直升机飞行时的风场进行了测量试验,目的在于探明无人直升机在辅助授粉作业时不同方向的风速和风场宽度等参数,以便决策出较佳的飞行作业参数,包括飞行高度、作业航向等。无人直升机授粉作业的飞行速度设置为3m/s,作业载荷为3.75kg,飞行高度为:9、8、7和6m,测量的风向为:平行于飞行方向(X)、垂直于飞行方向(Y)、垂直于地面方向(Z)。测量试验结果表明,上述3个风向的风速值大小排序为VX>VY>VZ,且风速持续稳定,因此,在直升机辅助水稻授粉作业时,平行于飞行方向的风力(即沿着直升机前进方向的飞机尾风)更有益于辅助授粉作业;随着飞行高度不断降低,风场宽度亦有所增加,在飞行高度为6～8m时,达到3级风的风场宽度最大可达到9m,飞行高度为9m时,达到3级风的风场宽度最大仅为4m,明显缩小,综合考虑农艺要求、作业效率及安全性等因素,该文建议无人驾驶油动单旋翼直升机Z3机型的较佳飞行作业高度为7m;直升机逆自然风方向飞行作业时到达水稻冠层的风力较小,很难形成能满足水稻制种授粉所需的风场宽度和风速,而顺风方向飞行时的风场宽度和风速较大,因此采用油动力无人直升机辅助水稻制种授粉时,宜避免逆自然风方向飞行作业。该研究可为无人直升机水稻制种辅助授粉技术的发展提供参考。

Wind field measurement for supplementary pollination in hybrid rice breeding using unmanned gasoline engine single-rotor helicopter

Abstract: The unmanned helicopter has been widely used in agricultural plant protection because it is operationally flexible and does not require a special airport. To achieve full mechanization in hybrid rice breeding, it is necessary to expand the planting width of the male and female parents of hybrid rice. The wind made by the helicopter rotor can spread the paternal pollen farther, making it possible to achieve full mechanization in hybrid rice breeding. There are close relationships among the seed setting rate, operating efficiency, cost-effectiveness, and the parameters of the unmanned helicopter flight, including the wind speed, wind direction and wind field width. However, studies are scarce in this area so far. To explore the optimization parameters while the unmanned helicopter conducts supplementary pollination, including flight altitude, operating load, and operating heading, in this study a wireless wind speed sensor network measurement system (WWSSN) was used to measure the wind field of an Unmanned Gasoline Engine Single-Rotor Helicopter (UGESRH). The flight speed of UGESRH was set to 3 m/s, the operating load was 3.75 kg, and the flying heights tested were 9, 8, 7, and 6 m respectively. The measured wind directions of the WWSSN included parallel to the direction of male parent ridge (X), perpendicular to the direction of male parent ridge (Y), and the vertical direction (H). The test results showed that the wind speed value is VX>VY>VZ, and the wind in direction X is more useful to the supplementary pollination. As the flight altitude decreased, the width of the wind field increased; at operating heights of 6-8 m, the maximum wind field width at wind grade 3 was more than 9 m; when the operating height reached 9 m, the wind field width at wind grade 3 decreased to 4 m. Considering all the various factors together, including the operating efficiency and flight security, a flight height of 7 m is suggested based on the UGESRH-Z3 model unmanned helicopter that we used. The test results also showed that the critical forward wind speed is very small when the UGESRH operates in a headwind, compare with its flight at the downwind direction. Therefore, operation in a headwind is not suggested while using UGESRH to conduct supplementary pollination.