Constant pressure control for variable-rate spray using closed-loop proportion integration differentiation regulation

  • Wei Deng | dengw@nercita.org.cn Beijing Research Center of Intelligent Equipment for Agriculture; National Research Center of Intelligent Equipment for Agriculture; Key Laboratory of Agri-informatics, Ministry of Agriculture; Beijing Key Laboratory of Intelligent Equipment Technology for Agriculture, Beijing, China.
  • Chunjiang Zhao Beijing Research Center of Intelligent Equipment for Agriculture; National Research Center of Intelligent Equipment for Agriculture; Key Laboratory of Agri-informatics, Ministry of Agriculture; Beijing Key Laboratory of Intelligent Equipment Technology for Agriculture, Beijing, China.
  • Liping Chen Beijing Research Center of Intelligent Equipment for Agriculture; National Research Center of Intelligent Equipment for Agriculture; Key Laboratory of Agri-informatics, Ministry of Agriculture; Beijing Key Laboratory of Intelligent Equipment Technology for Agriculture, Beijing, China.
  • Xiu Wang Beijing Research Center of Intelligent Equipment for Agriculture; National Research Center of Intelligent Equipment for Agriculture; Key Laboratory of Agri-informatics, Ministry of Agriculture; Beijing Key Laboratory of Intelligent Equipment Technology for Agriculture, Beijing, China.

Abstract

Traditional sprayers adopt large-area uniform pesticide application, resulting in a low effective utilisation of pesticide and a harmful effect to the natural environment. Variable-rate spray is the key point to precision chemical application. However, it is inevitable that the spray pressure sharply fluctuates during variable-rate spray, which will definitely influence the spray characteristics, such as spray droplet sizes, spray angles, spray droplet velocities, etc., and reduce the efficiency of pesticide applications. Therefore, the research on how to keep the spray pressure constant during the process of variable- rate spray has practical significance to precision pesticide applications. In order to achieve the stability of spray pressure for variable- rate spray, a sprayer with constant-pressure control was set up using a closed-loop proportion integration differentiation (PID) controller of constant-pressure water-supply, which employed the techniques of single-phase alternating current (AC) chopper variablevoltage control and PID feedback regulation. Using hollow-cone nozzles, the spray volume was changed by adjusting spray pressure, frequency, and duty cycle of electromagnetic valve switching. The spray features concerning the spray angle and the spray volume distribution were studied in laboratory. The conclusions are as follows: i) for a given input spray pressure, the closed-loop controller with AC chopper and PID feedback regulation can effectively control the pressure fluctuations during the variable-rate spray through varying the frequency and the duty cycle; ii) the spray angle was slightly affected by the flow-rate change through adjusting the frequency and the duty cycle of electromagnetic valves or changing the number of open nozzles. The spray angle changes were controlled within the range of the maximum deviation 0.87° from mean value and the minimum deviation 0.03° from mean value; iii) when the spray pressure was set as 0.3 Mpa, the peak radial position of the spray volume distribution basically unchanged and the spray volume and the peak values of the spray distribution gradually increased with the increasing duty cycle. When the setting pressure was increased, the spray volume increased and the peak radial position of the spray distribution gradually expanded toward outside, however the peak value of the spray distribution decreased a little.

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Author Biography

Wei Deng, Beijing Research Center of Intelligent Equipment for Agriculture; National Research Center of Intelligent Equipment for Agriculture; Key Laboratory of Agri-informatics, Ministry of Agriculture; Beijing Key Laboratory of Intelligent Equipment Technology for Agriculture, Beijing

I am an associate researcher in National Engineering Research Center for Information Technology in Agriculture (NERCITA), China. My main Research Field is Precision Chemical Application. A resource-saving and environment-friendly world is needed for all of us. Therefore I decided to contribute more to this area and have done some research work on it. A kind of PWM-based continuous variable spray equipment was built up during my research for Ph.D degree. I compared spray characteristics among PWM-based continuous, PWM-based intermittent, and pressure-based variable spray, in the aspects of spray distribution pattern, spray angle, spray droplet size, spray velocity, spray specific energy, and kinetic energy median diameter so as to provide some foundation to apply these technique in various and suitable conditions of chemical application. During the research work of post-doctor, I did some research on spectral detection technology for targeting spray. Two main parts of Precision Chemical Application (PCA) have been involved in my research work. And I am going to do more and deeper research work on PCA.

Published
2016-09-29
Section
Original Articles
Keywords:
Variable rate application, spraying, pressure, stability, agricultural chemical.
Statistics
Abstract views: 1508

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How to Cite
Deng, W., Zhao, C., Chen, L., & Wang, X. (2016). Constant pressure control for variable-rate spray using closed-loop proportion integration differentiation regulation. Journal of Agricultural Engineering, 47(3), 148-156. https://doi.org/10.4081/jae.2016.512