Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System
AbstractTo realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy. View Full-Text
Scifeed alert for new publicationsNever miss any articles matching your research from any publisher
- Get alerts for new papers matching your research
- Find out the new papers from selected authors
- Updated daily for 49'000+ journals and 6000+ publishers
- Define your Scifeed now
Cai, X.; Walgenbach, M.; Doerpmond, M.; Schulze Lammers, P.; Sun, Y. Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System. Sensors 2016, 16, 127.
Cai X, Walgenbach M, Doerpmond M, Schulze Lammers P, Sun Y. Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System. Sensors. 2016; 16(1):127.Chicago/Turabian Style
Cai, Xiang; Walgenbach, Martin; Doerpmond, Malte; Schulze Lammers, Peter; Sun, Yurui. 2016. "Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System." Sensors 16, no. 1: 127.
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.