Research On Pesticides Concentration Control Of Online Mixed Tractor Mounted And Embedded Implementation

Since entering the modern agriculture,the use of large-scale tractor-mounted machine is more and more common,and precision agriculture has become the goal of agricultural production.Our country has a big gap with developed countries in this area.In particular,because of large-scale spray system's pressure,operation speed,change of spray concentration and so on,which cause the low utilization rate of pesticides for large-scale tractor-mounted machine in the spraying process.There is a phenomenon of over or lack of spray,resulting the serious waste of pesticide and environmental pollution.It is urgent to solve the problem of intelligent control of the spray system of large tractor-mounted machine.The thesis analyses the spray system of large scale tractor mounted,determining the key problems affecting the efficiency of spraying.The spray concentration of the tractor mounted machine is modeled,and the spray concentration controller is designed.Because the system has serious nonlinear and uncertainty,the fuzzy PID control algorithm adopted to ensure good control effect.During the operation of the tractor mounted,by adjusting the valve of the pesticides mixture system,regulating the duty ratio signal of the size of the proportional valve,the concentration of the spray is controlled and reached to the set value.Then the spray concentration controller is simulated in the Simulink software,and the concentration can accurately be controlled in the different pesticides injection pump speeds.Based on the validation effectiveness in Simulink software,the spray concentration controller of online mixed pesticides tractor-mounted machine is developed for engineering.So the controller is developed based on embedded system and CAN bus.The ISO11783 communication protocol of agricultural machinery CAN bus is analyzed.STM32F103 as the core of the controller,peripheral circuit,LCD display circuit and CAN line communication circuit are designed.The embedded software of fuzzy PID control strategy,the concentration control program of the tractor mounted,the CAN bus communication protocol program and the LCD display program,which are compiled.The host computer as the spray system,the lower computer as the developed embedded system controller,the experiments of the spray system is carried out.The experiments result show that,the embedded controller can display the working state of the on-line mixedpesticides tractor mounted correctly and complete the data transmission of the spray concentration controller and the on-line mixed pesticides tractor mounted.The fuzzy PID controller embedded software controls to reach the desired concentration of spray effectively.