摘要
为了实现农药变量喷洒,准确计量和控制农药的注入速率和注入量很有必要。提出了一种喷嘴直接注入式系统(DNIS)原型,并在此基础上研究了农药喷洒量的控制方法。该系统应用快速响应电磁阀(RRV)向水中注入农药,RRV由100 Hz的脉宽调制(PWM)信号驱动,通过改变PWM信号占空比调节农药注入速率。试验室环境下设计了基于比例-积分-微分(PID)算法的闭环控制策略,将农药注入速率快速稳定在设定值。通过试验测试了RRV、DNIS系统和PID控制器的工作性能。试验结果表明,采用RRV可准确计量农药注入速率,闭环控制策略可获得较稳定的农药速率控制效果,农药注入速率可在4 s内达到设定值,注入速率的稳定性相对于没有控制策略有明显提高。
To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presented a prototype of direct nozzle injection system （DNIS） based on which method of controlling chemical injection rate was studied. In this DNIS, a rapid-reacting solenoid valve （RRV） was utilized for injecting chemicals, and it was driven by pulse-width modulation （PWM） signal at 100 Hz, adjusting the chemical injection rate with varying pulse width. A closed-loop control strategy based on proportional- integral- derivative （PID） method was applied to meter and stabilize the chemical injection rate. Laboratorial experiments were conducted to, assess the performance of RRV, including effect of PWM signal with start-up time on pesticide injection, the power consumption of RRV, the input - output characteristics of RRV, and the time elapsed of shutting down pesticide flux completely. The performance of DNIS and PID controller on stabilizing pesticide injecting rate was also evaluated, not only output of flowmeter but also electric conductivity measuring method were employed to indicate the stabilization of pesticide. Test results showed that RRV was capable of precisely metering chemical injection rate. With PID controller, the set-point chemical flow rate could be achieved within less than 4 s, and the stability of chemical flow rate was also improved against without control strategy.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2016年第11期100-105,共6页
Transactions of the Chinese Society for Agricultural Machinery
基金
中央高校基本科研业务费专项资金项目(BLX2013033)
国家自然科学基金青年基金项目(31400621)
国家自然科学基金项目(31371537)
中德合作小组项目(GZ494)
关键词
农药变量喷洒
直接注入式
快速响应电磁阀
脉宽调制
闭环控制
quantitative pesticide spraying
direct injection
rapid-reacting solenoid valve
pulse widthmodulation
closed-loop control
