Design Of Pesticide Spraying System With Variable Droplet Parameters And Experimental Research

Pesticide spraying is a necessary task to ensure the smooth progress of agricultural production,it has an important impact on China’s national economy and people’s livelihood.Traditional method of spraying pesticides on the ground were replaced by the aerial spray method gradually for its defects: inefficiency,serious pesticide residues,and environmental pollution.In addition,droplet diameter in low volume or ultra low volume spray operation is easy to change due to volatilization in the descent process,the speed of evaporation tend to change in different surrounding spray environment,different pests need to match droplet with different parameters,droplet parameters need to meet the BODS(Biological Optimum Droplet Size)theory,most of pesticide spraying systems do not take the droplet evaporation into account.In order to solve the above problems of pesticide spraying,this thesis designed a spray system with variable droplet parameters,and developed a prototype,tests were conducted to evaluate the system prototype.According to pesticide spraying task,the related theories used in system design were discussed,overall technical scheme and main technical indexes of system prototype were determined.Based on in-depth research in agricultural machinery market and urgent needs of agricultural machinery users,overall technical scheme were determined,including structure of system structures,the lower computer hardware,software design and host computer development.According to overall technical scheme,system of liquid sample waterway system was set up,the hardware circuit of lower computer system was designed,and the lower computer and host computer embedded software development were completed,by the test,feasibility of the whole technical scheme was verified.To this step,the system prototype was completed preliminary.The relationship between droplet parameters and experimental factors,along with the precise adjustment of atomizing disk speed are the key to the final completion of system prototype,this thesis has carried on the related experiment design.The speed of atomizing disk was measured and fed back to the main controller according to the characteristics of brushless DC motor.By the orthogonal rotation combination test,it was verified that the temperature,humidity and droplet deposition distance have an effect on droplet volatilization,and regression equation between the speed of atomizing disk and experimental factors was obtained.In addition,atomizing disk speed and PWM signal duty cycle are not the linear relationship strictly,so calibration test was conducted by quintic polynomial.The spray environment varies from time to time,actual speed was difficult to follow the theoretical speed,in this thesis,variable speed integral incremental PID algorithmthe was adopt to optimize the atomizing disk speed system,and the feasibility of algorithm was verified by MATLAB simulation.At last,the system prototype was finalized.In order to evaluate the system,spray tests were designed,the results show: system technical indicators set originally were conformed basically,the deviation of the droplets parameters were within the acceptable range.This thesis provides a research idea for the field of precision agriculture,the conclusions can provide valuable guidance for practical spraying operations.