Research On Control System Of Variable Spraying Based On Pulse Width Modulation

Since the reform and opening up,the rapid improvement of agricultural productivity in China has promoted the economic development.At the same time,the use of pesticides becomes more frequent and common because of the diseases and insect pests.In this way,the utilization of pesticides is low and environmental pollution becomes more serious.With the development of agricultural mechanization,the operation area of farmland is becoming larger and larger and the disadvantages of traditional spraying are becoming more and more serious.We must overcome the disadvantages of these traditional spraying methods thoroughly by implementing variable spraying technology.In order to achieve high yield,high quality,high efficiency and environmental protection,we should use different input methods of pesticide.Therefore,the implementation of variable application technology is an inevitable choice to promote the ecological environment protection and the sustainable development of agriculture.Combining with Jiangsu Science and Technology Support Program "Spray Boom Transformation Technique and Development of Multifunctional Pesticide Target Sprayer(BE2012383)”as well as Jiangsu Agricultural Machinery Three New Project" Development of Multifunctional Variable Spray Boom Smart Sprayer NJ2014-11”,the research on control system of variable spraying based on pulse width modulation has been carried out and the following work has been completed:(1)The whole design of variable spraying control system was completed and the scheme of pesticide supply system was determined based on the idea of pulse width modulation.According to the specific requirements of variable spraying,the algorithm of the control system,the main components of the pesticide supply system and the type of the detection device are determined.(2)According to the overall scheme of the control system,we have configured diaphragm pump,overflow valve,main pipe valve,flow sensor,pressure sensor,high speed solenoid valve and nozzle,and constructed a set of control system of variable spraying based on pulse width modulation.(3)According to the functions that the system needs to be implemented,the circuit principle diagram of variable spraying controller has been drawn and the board of control circuit has been designed and made.In order to realize the control requirements of each module,the C language is used to design the control program.The pre application test is carried out and the functions of each module of the controller are normal.(4)The test platform of the control system of variable spraying based on pulse width modulation was built and the pressure,PWM frequency and duty ratio were setto measure flow rate of the nozzle.Under the same working condition,testing 3times to get the flow rate and take the average value.The mathematical model is established by BP neural network algorithm and the experimental data are fitted.At the same time,the feasibility of applying the pulse width modulation to the control system of variable application is verified.