Design Of Variable Pesticide Application Monitoring And Control System Of Pesticide Application Machine Hauled By Tractor

Variable pesticide application is one of the most important measures for spray value of per unit area to meet the agricultural requirements, reducing the use of pesticide and chemical pollution. Some of the pesticide application machines can not spray pesticide variably, monitor on line, store the pesticide application parameter data and control nozzles independently at present. On the basis of such situations, a variable pesticide application monitoring and control system of pesticide application machine hauled by tractor was designed. The system can store and display the pesticide application parameter data while monitoring and control the spraying volume according to the speed of the tractor to stabilize pesticide application volume on per unit area and control the pressure based on the setting data, besides that it could also control nozzles independently by using soft keyboard.(1) The overall requirements of the system, which included that the system could spay pesticide variably, monitor on line and control nozzles independently, were determined. After comparision and analysis of different schemes, the system's scheme was determined, which was that the system can change the spray volume based on the speed of the tractor and the setting spray volume, change the pressure based on the setting data, monitoring the spray situation by LCD and PC, and control the nozzles by soft keyboard, was ensured through the compare and analysis of schemes.(2) The pressure and spray volume control models were established and the PID and fuzzy control algorithm were designed and simulated. The results showed that the response time of pesticide pressure and spraying volume control were 0.85s and 1.04s respectively under the PID control, and were 40ms and 55ms respectively under the fuzzy control. Hysteresis control algorithm was optimized by jumping control step size.(3) The executive components, testing components and the other equipment were chosen according to the system's scheme. And circuit modules including power supply, keyboard, LCD displayer, communication, storage of SD card, control circuit of electronic ball valve and solenid valve, and so on were designed, meanwhile the PCB board and the system's controller was made. The system's master computer software and lower computer software were designed. Among them, the master computer software's program included construction of database, system registration, system login, system settings and reception, display, storage and analysis of data, etc. While the lower computer software's program conained system initialization module program, LCD display, keyboard scanning, data sampling, storage of SD card, serial communication and control modules programs, etc.(4) The system debugging and verification experiments were finished, which showed that the system's master computer can receive, store and display the pesticide application parameter data, while the lower computer can display and store the data. The average measuring accuracy of speed, pressure and spray volume was 97.7%, 98.5%and 99.3% respectively. The system can control twenty nozzles independently by using soft keyboard.(5) The optimization experiment of hysteresis control algorithm was done and the results showed that the average recovery time was twelve seconds and seven seconds respectively at the spray volume being 200ml/s while control the spray volume by hysteresis control algorithm with the same control step and jumping control step, and the average error was 27.19% and 13.24% respectively in the recovery time, while the average error was 12.68% and 7.55% respectively in the whole control process. The average recovery time was 13.4 seconds at the pressure being 0.75MPa, when controlled the pressure, and the average error was 25.49% and 14.42% respectively during the recovery time and the whole control process.