Study On The Pollen Movement Of Rice Based On The Wind Field Of Unmanned Aerial Vehicle

The rice are pollinated with the spread of wind in period of seed production. The UAV is widely used in hybrid rice pollination operation. At the time of pollination, the wind field of rotor has a significant effect on the distribution of rice pollen which is directly related to quality of hybrid rice seed production.In order to find out the distribution of rice pollen under the wind field of small UAV, the paper use high~speed camera to try to capture image of pollen movement trajectory, and combined with wind tunnel simulation test which collect wind field parameters and pollen data of all sampling points in wind tunnel, research the relationship between three different initial wind speed under the condition of wind field parameters and rice pollen distribution. In addition, the paper use Beidou Positioning System UB351 to accurately grasping each sampling point position and spacing, and the rendering system of UAV flight trajectory, providing accurate reference data for test. And the paper measured three wind field produced by rotor under amount of different experimental factors, and got wind field width, wind speed through the use of wind field wireless network measurement system. Finally, the paper contact with the pollen distribution area ratio and pollen distribution width of UAV pollination operation, and used the Shapiro Wilk, Kolmogorov-Smimov statistics to do a normal test. In order to select appropriate flight speed of UAV pollination operation according to the trend of pollen distribution, the paper establish regression model. The main research contents are described as follow:(1) According to the principle of high~speed camera, set the parameters of test environment under high speed camera, including focal length, video frequency and so on. After completing the test scene arrangement and the parameter settings, capture image of chalk dust moving, and do the threshold value, the chalk particle size which the paper calculated is larger than the pollen size. Therefore we get the conclusion of the high speed camera not taking into account pollen.(2) It turned out that, in a manner of wind field distribution of sampling points, the second test(initial wind speed 3.5 m/s) presents the widest wind zone of suspension speed; and the first test(initial wind speed 2.5 m/s) presents the most narrow wind zone of suspension speed; there is a little difference of wind field width between the third test(initial wind speed 4.5 m/s) and second test at each stage. In a manner of pollen distribution, the located 7# has the largest number in pollen in three test and the data of the first test is the minimum in all kinds of test(average density of pollen, distribution area ratio, distribution width). The difference between the second experiment data and the third data experiment is minor. The pollen quantity presents normal distribution approximately in each sampling point, and when the initial wind speed is 3.5 m/s in wind tunnel test, there are a linear relation between pollen quantity and wind speed value of sample point in wind tunnel test, which is concentrated within the suspension speed of belt and is conducive to spread pollen.(3)The paper showed that the horizontal wind field generated by the UAV is mainly derived from y direction and the wind field width of y direction is maximum by comparing the wind velocity values of x, y direction; Moreover, flight speed is the main factor affecting the width of wind field, and the width of horizontal wind field decreases with the increase of flight speed. At the same time, the vertical wind field is affected significantly by UAV flight speed; the distribution width and the area ratio of the pollen grains more than 5 pcs are the largest which is the most conducive to pollen dispersal when the flight speed was 4.53 m/s, and it also showed that the distribution of pollen is not only related to the width of the wind field, but also affected by the flight speed of the UAV. The effect of wind field on the distribution of pollen produced by the UAV is asymmetrical, which is compared with the pollen amount of 1#~10# sampling point and the amount of 11#~20#. The non~normal distribution of pollen quantity under the wind field is obtained by the Q~Q plot of spss software. And the distribution of pollen is only linear relationship with the x direction wind field generated by the UAV. The results provided theoretical basis for rice pollination of the UAV and provided a reliable theoretical basis for the development of machinery, which has played an important role for the development of hybrid rice seed production technology.