Design and Experimental Testing of a Control System for a Solid-Fertilizer-Dissolving Device Based on Fuzzy PID

Xiuhua Song, Hong Li (), Chao Chen, Huameng Xia, Zhiyang Zhang and Pan Tang
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Xiuhua Song: Research Center of Fluid Machinery and Technology, Jiangsu University, Zhenjiang 212013, China
Hong Li: Research Center of Fluid Machinery and Technology, Jiangsu University, Zhenjiang 212013, China
Chao Chen: Research Center of Fluid Machinery and Technology, Jiangsu University, Zhenjiang 212013, China
Huameng Xia: Research Center of Fluid Machinery and Technology, Jiangsu University, Zhenjiang 212013, China
Zhiyang Zhang: Research Center of Fluid Machinery and Technology, Jiangsu University, Zhenjiang 212013, China
Pan Tang: Research Center of Fluid Machinery and Technology, Jiangsu University, Zhenjiang 212013, China

Agriculture, 2022, vol. 12, issue 9, 1-15

Abstract: To overcome the problem of poor uniformity of solid-fertilizer-dissolving devices due to lag of fertilizer dissolution, a closed-loop control system based on fuzzy proportional-integral-derivative (PID) was designed and tested. A fertilizer concentration regulation model was then established according to the results. In this system, the control core was an STM32 used to feed back the fertilization concentration by detecting the electrical conductivity. For real-time adjustment of the fertilizer flow rate and water flow rate, a fuzzy PID control algorithm was utilized to compare the detected concentrations with the set concentrations. The linear relationships between quantities such as the fertilizer rate and PWM frequency, water flow rate and PWM duty ratio of the direct-current pump, and fertilizer concentration and electrical conductivity were all established to calibrate the system. The influence of the fertilizer flow rate and water flow rate on fertilizer concentration was determined by the control variable test method. The results showed a positive linear relationship between fertilizer concentration and fertilizer flow rate, while a reverse linear relationship was established between fertilizer concentration and water flow rate. After the introduction of the control system into the self-developed solid-fertilizer-dissolving device, the fertilizer concentration fluctuated near the set concentration in a range of no more than 1 g/L. After the disturbance of the fertilization device, the control system fine-tuned the device with a steady-state error of about 0.55 g/L after the system reached stability. The control system designed in this study was shown to run normally with good stability, speed, and accuracy, and with improved fertilization uniformity of the solid-fertilizer-dissolving device. This study lays the foundation for further study of fertilization control systems. It also provides a reference for the development of precise and intelligent fertigation.

Keywords: fertilization uniformity; closed-loop control; single-chip microcomputer; fuzzy PID; solid-fertilizer-dissolving device (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2022
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