Design Of Automatic Pesticide Mixing Device For Spraying Unmanned Aerial Vehicles

China is a large agricultural country.Crop pests and diseases are one of the major agricultural disasters.The extent and severity of the crops often cause significant losses to our national economy,especially agricultural production.At present,the control of crop pests and diseases mainly relies on the chemical control of pesticide application.Most of the existing pesticide formulations need to be diluted with water and formulated into a certain concentration before application.In recent years,China’s agricultural aviation has developed rapidly,and the demand for intelligent agricultural machinery and equipment for agricultural aviation has become very urgent.The pesticide automatic mixing device controls the whole mixing process through the control system and the sensor group.The ideal pesticide mixing device can accurately measure the amount of clean water and the amount of pesticide entering the mixed drug area,and after effective mixing and mixing,the liquid mixture is mixed.After being evenly distributed,it is added to the working machinery medicine box to ensure uniform mixing of pesticides,mixing precision of liquid medicine,improving pesticide utilization rate,and enhancing the effect of mechanical spraying operation.In order to improve the precision of pesticide spraying machinery,especially the plant protection drone operation and the application effect,an automatic pesticide mixing device was designed.The numerical simulation and experimental exploration were used to design the mechanical structure and control system of the device.Major aspects such as core component selection and performance testing have been studied.The main research work and results are as follows:1.Designed an automatic pesticide mixing device that can be used for plant protection drone spraying.The device uses syrup separation,real-time preparation,thorough mixing and precise ratio,which can effectively control the dosage of pesticides in the mixing box.The amount of water infused with the clean water and the amount of liquid that is transported to the spray box of the spraying equipment to accurately measure the dilution ratio and concentration of the pesticide.The pesticide automatic mixing device mainly consists of two parts: the mechanical structure and the control system.The mechanical mechanism includes the mixing box,the pesticide box,the agitator,etc.The control system is based on the STM32 single-chip microcomputer,including the flow sensor group,the solenoid valve group,and the stirring.The mechanism,the water pump,the medicine pump,the touch screen,other sensors and the like are composed of components,and the control system can meet the requirements of real-time control of medicine,mixed medicine,and medicine delivery.2.Three-dimensional modeling software is used to construct three-dimensional models of three different types of agitators,such as turbine agitator,paddle agitator and propeller agitator.Based on computational fluid dynamics,three different types of agitation are performed by SIMPLEC algorithm.The numerical simulation calculation was carried out to analyze the velocity field of three different types of mixers mixed at different speeds.The final results of numerical simulation show that the turbine agitator has the best mixing performance at the same stirring speed,and the stirring influence range is larger,which can better promote the mixing of pesticide and water.In addition,the numerical simulation of the mixing time of different agitators was carried out.The mixing time and flow field of the three agitator mixtures were simulated by the tracer concentration method at the same speed.The numerical simulation results show that at the same speed,the turbine type The agitator flow field is evenly distributed,which accelerates the mixing of pesticides and water with the shortest mixing time.3.In order to verify the results of the numerical simulation calculation,the glycerin with the temptation red stain was used as the pesticide substitute,and the high-speed camera was used to collect the picture of the mixing operation at the same speed,and the temptation red was mixed.The box can be judged to be evenly mixed at this time,and the mixing time is obtained according to the collected picture.The test results finally show that the simulation results are in good agreement with the test results,which provides a reference for the application of the agitator in the pesticide automatic mixing device.4.The pesticide uniformity test,the mixed drug stability test and the water and drug flow response speed test were carried out on the pesticide automatic mixing device.The results of the mixed drug uniformity test showed that the actual concentration coefficient of the mixed solution was less than 5% when the proportion of the mixed drug was less than 1000:1;the same mixed drug stability test showed that when the mixed ratio was less than 1000:1,The relative error of the actual concentration of the mixed liquid is less than 5%;the water and drug flow response speed test results show that the flow rate of the clean water is 2L/min,the flow rate of the pesticide is 0.4L/min,and the flow rate of the drug is 1.7L/min.The test shows that when the proportion of mixed drugs is less than 1000:1,the designed mixed pesticide automatic mixing device has better comprehensive performance,which can meet the needs of plant protection and drug mixture operation.