水肥一体机控制系统设计与试验

Design and test of the control system of integrated irrigation and fertilizer applicator

针对目前水肥一体机控制系统存在调节时间长、配比波动大等问题,采用PID变量注入、比例、EC/pH实时调节等技术,研发由PLC控制器、触摸屏、I/O模块、EC/pH传感器等组成的水肥一体机控制系统。研究硬件组成、吸肥流量检测方法、基于比例、EC/pH的变量施肥控制方法和策略,编制相应的控制软件,构建完整的控制系统。通过试验检测控制系统的性能,对PID参数进行优化。采用优化后的参数,水肥一体机的比例调节范围为4‰~20‰,响应时间为80 s,最大超调量小于5%,稳态精度为3%;EC调节范围为800~4000μs/cm,响应时间为80~120 s,稳态精度为4%;pH响应时间为120 s,稳态精度为±0.1。

Aiming to solve the problems of long adjustment time and large proportion fluctuation in the current control system of integrated irrigation and fertilizer applicator,the control system composed of PLC controller,touch screen,I/O module,EC/pH sensor was developed by using the technologies of PID variable injection,and proportion,EC/pH real-time adjustment.The hardware composition,fertilizer suction flow detection method,and variable fertilization control method and strategy based on the proportion and EC/pH were studied.The corresponding control software was compiled,and a complete control system was constructed.The performance of the control system was tested,and the PID parameters were optimized.Using the optimized parameters,the proportion adjustment range of the water fertilizer integrated machine was 4‰-20‰,the response time was 80 s,the maximum overshoot was less than 5%,and the steady-state accuracy was 3%.EC regulation range was 800-4000μs/cm,the response time was 80-120 s,and the steady-state accuracy was 4%.The pH response time was 120 s,and the steady-state accuracy was±0.1.