Design and experiment of rapeseed aerial seeding device used for UAV

Considering the rapeseed planting area is large in hilly and montanic area and the planting period for rice and rapeseed is partly overlapped in flat area in China, a rapeseed aerial seeding device used for UAV was designed in this paper. The rapeseed aerial seeding device included two parts: seeding device and control system. The working power come from UAV. Structure parameters of seed box volume, seed-filling funnel and geneva wheel of aerial seeding device were confirmed. The volume of seed box was 5.2 L so that it provided enough rapeseed for UAV to seeding 0.67 hm2 area at one operation. The upper inlet shape of seed-filling funnel was a rectangle with length 30 mm and width 18 mm. The down outlet shape of seed-filling funnel was a circle with diameter 15 mm. The length of seed-filling funnel was 49-65 mm. The diameter of geneva wheel seed metering device was 80 mm with 30 type holes per circle in circumferential direction. Aerial seeding control system contained hand tele-control system and airborne tele-control system. The airborne tele-control system contained main controller (STM32 single chip), BeiDou Navigation chip, piezoelectric sensor, stepping motor with driver, flying information detection module, wireless transmission module and power module. The hand tele-control system contained controller, display screen, wireless transmission module, power module and keys. When the UAV was in the working field, the location information of UVA was detected by flying information detection module and the aerial seeding device started to seeding. The aerial seeding device stopped to seed when the flying information detection module detected that the UAV was out the working field. Hand tele-control system communicated with the airborne tele-control system acquired the flying information and then controlled the seeding rate of metering device when the UAV was flying. In order to analyze the factors affecting the working performance of aerial seeding device, the simulation model of airflow field of UAV rotor wing was established and the effects of rotor wing to airflow field was analyzed. The simulation results showed that the airflow field conducted by rotor wing affected the rapeseed falling track obviously. With the flight height of UVA increased, the range of space airflow field affected by UVA wings increased, and the distribution area of rapeseed landing on the ground increased. The relationship model between the UAV flight speed and geneva wheel rotary speed was established by selecting the length of seed-filling funnel and geneva wheel rotary speed as the factors based on the bench est. The results showed that when the distance between outlets of seed guiding tube and rotor wing was 300 mm, the length of seed-filling funnel was 53 mm, geneva wheel rotary speed was 10-50 r/min, the geneva wheel seeding rate met the requirements at the UAV flight speed of 2-4 m/s. The pavement test was conducted and the results showed that the effective working width was 2.15-2.45 m, coefficient of variation of seed distribution uniform was 32.05%-34.78% at the cross distance of seed tube outlets of 1.1 m, UAV flight height of 2-2.5 m. The average seedling density of field experiment was 64.5 plants/m2, the coefficient of variation of seed distribution uniformity was 38.23%, which meet the requirements of rape cultivation This study can provide a reference for the design of UAV aerial seeding device. In order to further optimize the working performance of UAV aerial seeding, it is necessary to conduct comprehensive tests under natural wind and different field conditions in the future research work. © 2020, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.