Research On Real-time Mixing Control System For Variable Sprayer

China is a large agricultural country with a large amount of pesticides used.With the development of fine agriculture,the crops ensure high yields while paying more attention to ecology and safety.Online drug mixing technology has the advantages of high utilization rate of pesticides and low environmental pollution,which has attracted a lot of attention from many scholars.Aiming at the problems of the general mixing system,such as narrow mixing ratio adjustable range and small pesticide flow,it is difficult to control.In this paper,a real-time mixing control system is designed.The mixing ratio adjustment range is large,the error is small,and the system is stable.And the uniformity of the mixed medicine is good.In order to enable the real-time mixing control system to be used with variable sprayer,this paper studies the laser detection technology.A laser detection module is designed to use it for target detection and calculate the target volume,and then calculate the required amount of drug mixing,so that the real-time drug mixing control system can achieve drug mixing on demand and improve pesticide utilization.The structural parameters of the drug mixing device,the key component of the drug mixing system,are optimized to achieve the highest drug mixing efficiency within the applicable range.The main contents of this paper are as follows:1)Studying the mixing efficiency of the drug mixing device,using the area ratio,the distance between the nozzle and the suction port as variable parameters,based on the response surface method,a mathematical model of the drug mixing efficiency of the drug mixing device was established,and the interaction of the three influencing factors was studied.Solve the multiple regression equation of the mathematical model by Design Expert 10.0.7 software,optimize the structure parameters of the medicine mixer within the applicable range,and make the medicine mixing efficiency reach the best.2)Design the laser detection module,compile and debug the laser sensor data acquisition and processing programs on the microcomputer.Using the simulation tree as the test object,the scanned target is reconstructed to obtain and calculate the three-dimensional feature information of the target.The test results show that the height,width,and canopy height information of the simulation tree obtained by the laser detection module are related to manual measurement In comparison,the maximum errors were 4.67%,5.45%,and 4.65%,respectively.3)Design the medicine supply control module,adjust the working voltage at both ends of the peristaltic pump through the PWM signal,a voltage feedback circuit is designed to form a closed-loop control.The medicine supply module uses a software interrupt to generate the PWM signal.A PI controller is used to feedback control the PWM duty cycle.The experiment and analysis of the flow rate of the liquid medicine,and the function model between the flow rate of the peristaltic pump and the duty cycle of the PWM signal is obtained.4)Complete the design of the real-time drug mixing control system for variable sprayer,so that it can achieve real-time drug mixing according to target information and drug mixing ratio.Finally,the entire system was mounted on a 3WG-8A air-feeding variable sprayer produced by Nantong Guangyi Electromechanical Co.,Ltd.to conduct a drug mixing control effect test.The test showed that the real-time drug mixing control system could achieve the on-demand drug mixing The drug ratio is adjustable in real time between 140: 1 and 400: 1,the overall error during system operation is less than 5%,and the system is stable and reliable.The maximum variation coefficient of the mixed drug concentration between the samples selected in the experiment is 8.20%,indicating that the system has good uniformity of mixed drugs.