| Based on the Lockheed 3W6LH-10ZI six-rotor electric plant protection UAV platform,this paper explores a high-speed precision aerial seeding and seeding system for air-supplied rapeseed,which can be used for the mechanization of rapeseed when ground machinery and equipment cannot be accessed or the economic benefits are not high.Seeding provides a technical equipment as a useful supplement to conventional ground seeding equipment for rapeseed.Focusing on the scheme design,structural design,prototype trial production,and optimization of working performance of the air-supplied aerial seeding system,a complete design scheme of the air-supplied rapeseed aerial seeding system was designed.Air-assisted seed metering,an automatic foldable seed guiding device and a seed metering control system that communicates with the flight control system.The main contents are as follows:（1）A special seed metering device for aerial seeding of rapeseed is designed.In order to overcome the problems of serious airflow backflow and difficulty in seed supply after the miniaturization of the seed supply device of the traditional air-feeding seed metering device,a vertical arrangement of the main conveying pipeline+quantitative seed supply on the side of the grinding disc type seed supply device,small fan was designed.Air-supplied seed metering device for aerial seeding of rapeseed with air-supplied seed supply+second-order air-delivery distribution below.The design calculation and analysis of key components such as the seed filling chamber,the seed supply rack and the distributor are carried out,and the thickness of the seed supply rack is determined to be 8 mm,and the width of the spacer is 2.5 mm.The frictional resistance torque received was 2.326×10-3N?m,the suspending speed of rapeseed in the conveying pipeline was 17.442 m/s,the conveying air volume per unit time of the fan was 14.938 m3/h,and the volume of the seed box was 4.5 L.The distribution process of gas-solid two-phase flow in the distributor is analyzed by the distribution method of one-to-two and three-to-three,and the structural size parameters of the first-order distributor and the second-order distributor are determined.（2）An automatic foldable seed guiding device was designed.In order to suppress the disturbance of the air flow conveyed by the fan of the seed metering device and the air flow of the UAV rotor to the movement trajectory of the seeds during the seeding process,an automatic foldable seed guiding and seeding device was designed.The seed tube consists of three parts.On the basis of clarifying the working principle of the gas-solid separator,the numerical simulation calculation and analysis of the structure are carried out.The analysis also found that the introduction of additional accelerating airflow was more conducive to eliminating the dispersion of the seeds,so it was changed to a"seed accelerator".,using a high-speed camera system to verify the effect of gas-solid separation on the impact velocity of seeds in the seeding tube.When the gas-solid separator is used,the average horizontal sub-displacement of the seed movement at the vertical displacement of 30 cm is reduced by 2.5 cm,and the average dispersion of the seeds in the mud box at 30 cm directly below the seeding tube is reduced by 6.2 cm;The airflow velocity at the end of the seed tube was 4.5 m/s,the average horizontal sub-displacement of the seed movement at the vertical displacement of 30 cm was reduced by3.1 cm,and the average dispersion of the seeds in the mud box at 30 cm directly below the seed tube was reduced by 7.9 cm.Through the kinematic analysis of the folding process of the seeding tube,it is obtained that the maximum torque of the seeding tube rotating around the central axis of the rotating head is 5.292×10-2 N?m.When the seeding tube is vertical,the angular velocity is 7.668 rad/s.The force of the central axis of the head on the seeding tube was 0.5292 N,the maximum stress of the rotating head seat during the stretching process was 4.0927×10-2 MPa,and the maximum stress of the rotating head seat during the folding process was 6.7227×10-2 MPa.（3）Numerical simulation analyzes the disturbance process of the rotor airflow field to the seeds after seeding.In order to explore the influence of the external airflow field of the seed metering system on the seed migration trajectory after seeding,a gas-solid two-phase flow simulation experiment was carried out for the whole process of seeding and seeding by using EDEM and FLUENT software based on the gas-solid coupling theory.The simulation results show that:in the process of seed feeding of the seed feeding device,the average velocity and average displacement of the particles moving from the seed filling chamber to the seed tube with the rotation of the seed feeding toothed disc are relatively stable,and the seed carrying performance of the seed feeding toothed disc is relatively stable.Well,when the rotation speed of the seed supply tooth plate is 25 r/min～45 r/min,the seed supply amount can change with the change of the rotation speed.With the increase of the fan inlet speed,the rape seeds are mixed in the gas-solid two-phase flow.The velocity of movement of both the zone and the first-order distributor outlet is increased.When there is airflow involved in the movement of rapeseed seeds in the vertical seeding tube,the airflow will affect the movement of the rapeseed seeds,increasing the number of collisions with the wall of the seeding tube,resulting in greater dispersion of the seeds after they fall.The UAV flies at a speed of 3 m/s.When the speed of the rotor flow field is small when it is 1.5 m directly below the UAV fuselage,it is selected to arrange the seeding tube directly under the UAV fuselage,using a foldable type.The method of guiding the seeding tube extends the end of the seeding port,and the movement trajectory of the rapeseed after leaving the seeding tube is less affected by the disturbance of the rotor flow field.（4）A set of special control system for aerial seeding and seeding is designed.According to the requirements of aerial sowing operations,the sensor circuit for material detection of the seed box,the control circuit for the seed supply motor,the control circuit for the fan and the folding motor,etc.are designed,and the communication program is written to realize the remote control（manual mode）and the UAV flight control system（automatic mode）.Start and stop control of the seed supply motor,fan and folding motor,as well as the speed control of the seed supply motor in the manual mode and the speed adjustment of the seed supply motor and the guarantee of the amount of seeding per mu under the automatic constant speed operation mode.The test shows that the control system works stably and reliably,and the sowing amount per mu under the automatic constant speed operation mode meets the agronomic requirements.（5）A series of experimental studies and verifications were carried out.In order to test the working performance of the above design scheme and optimize the operating parameters,the bench test of seeding performance,the field mud box aerial seeding test and the field test were carried out respectively.The test results show that:when the rotating speed of the seed supply rack is 25 r/min～45 r/min,the total amount of seeds per unit time of the seed metering system increases with the increase of the rotating speed.The seed amount was 396.90 g/min.The primary and secondary order of the influencing factors of the effect of rapeseed seeds falling into strips were flight height,flight speed,and rotation speed of the seed supply tooth disc.The speed of the disc has no significant effect on the effect of seeds falling into strips.When the flight height is 1 m,the flight speed is 3m/s,and the speed of the seed supply tooth disc is 45 r/min,the effect of seeds falling into strips is better.The bar width was 33.93 mm,and the bar formation index was 11.31%.The field test was carried out using the operating parameters of the flight height of 1 m,the flight speed of 3 m/s,and the rotation speed of the seed supply tooth disc of 45 r/min.Rape planting requirements. |
PDF Full Text Request