Design And Experiment Of Multi-Rotor UAV Trichogramma Pellets Delivery System

Trichogramma is often used to control pests and diseases of corn,cotton,rice and other crops.It has been released manually for a long time,and its application is often restricted by backward delivery methods.The Trichogramma spherical releaser(Trichogramma pellet)solves this problem,so that the Trichogramma realizes mechanized delivery and application.This paper proposes the design and research of a UAV for dropping Trichogramma pellets.Starting from the realization of the function of fixed-point delivery of Trichogramma pellets,the accuracy of the landing point of drones dropping Trichogramma pellets under flight status is studied.The main research content of this paper is as follows:(1)Based on the demand for fixed-point delivery of Trichogramma pellets,a dronemounted Trichogramma pellet delivery device was designed,and an indoor bench was built to test the working performance.According to the working requirements of drones for dropping Trichogramma pellets,a honeycomb storage device and a hammer-type delivery device are designed,and the delivery speed and frequency can be adjusted.Using a highspeed camera to study the influencing factors of the projecting speed of Trichogramma pellets,it is concluded that the reliable projecting speed range of the device is 2-5m/s,and the remote position is the optimal starting position of the lever.(2)The basic principle of UAV flight control is studied,and a six-rotor UAV is designed for the operational requirements of dropping Trichogramma pellets.According to the size and weight of the Trichogramma pellet delivery device,the flight control system,power system,center board,battery and other key components were selected and designed,and the arm was tested.Through the flight test,the stability of the UAV flight was tested,and the feasibility of the launch operation during the flight of the device was tested.(3)Using the fluid mechanics simulation software,the influencing factors affecting the deviation of the landing point of the Trichogramma pellets were studied when they were dropped in the state of constant speed flight.Based on the overlapping grid technology,the influence of flight speed,projecting speed and height on the large deviation of the Trichogramma pellet’s landing point was explored,and the relationship between the Trichogramma bee pellet’s landing point deviation and the projecting speed,flight speed and height under the simulation conditions was obtained.Model,in which the size of the deviation value is negatively correlated with the projection speed,and positively correlated with the flight speed and flight height.(4)Carry out three-dimensional modeling of the rotor,according to the measured motor speed,use Ansys software to numerically simulate and calculate the wind field of the sixrotor UAV in the hovering state involved in this paper,and obtain the airflow change law under the rotor of the model: multi-rotor without the wind field of a human helicopter is distributed symmetrically.Under the fuselage,the airflow generated by each rotor spirals downward,and the horizontal speed is low.The airflow disturbance area generated by the rotor gradually expands with the distance from the rotor,and the wind speed gradually weakens.The turbulent airflow under different rotors from 1m below crosses,and the speed in the horizontal direction gradually increases.Therefore,the position of the projection port should be set within 1m below the rotor,and the downwash airflow will appear "lead-in area" and "lead-out area".The phenomenon of distribution is more conducive to delivery in the airflow outlet area.Comparing the measured and calculated values of the airflow velocity in the z direction at 2m below the six rotors,the error is within 10%,indicating that the numerical calculation results basically meet the accuracy requirements.The field drop operation test was carried out at a height of 2.5m,and the results showed that when the flight speed was 2m/s and the drop speed was 4m/s,it was the optimal operation parameter,but the variation coefficient of deviation fluctuation was large(45%).