基于模糊自适应PID控制的智能配肥系统的设计与试验

Design and Test of Intelligent Fertilizer Distribution System Based on Fuzzy Adaptive PID Control

营养液可溶性盐浓度(EC)的调控是水肥一体化智能配肥系统中的重要技术之一,高浓度的EC值会使植物受到损伤或造成植物根系的坏死,EC值过低又不能供给农作物所需的养分。营养液混合过程中,由于营养液浓度、吸肥方法、混合方式和灌溉速度等存在的差异,使得EC值调节的过程存在很大的时滞和不稳定的现象,传统的PID控制很难取得良好的效果。针对上面的问题,根据水肥一体化系统的结构,建立相应的数学模型,对数学模型进行深入分析,进行Simulink仿真,并以STM32单片机为主控制芯片开发了一套具有自动混肥特性的营养液EC值智能控制系统。论文不仅在理论上对模糊自适应PID在智能配肥系统中进行了研究,而且进行了实际的应用,通过嵌入式系统进行了试验和对比。通过该研究可以表明模糊自适应PID能够使EC值快速、准确地稳定在设定值,能够满足实际需求。

The regulation of soluble salt concentration(EC)in nutrient solution is one of the important technologies in the integrated intelligent fertilizer distribution system of water and fertilizer.High EC value may damage plants or cause necrosis of plant roots,and the EC value is too low to provide nutrients for crops.In the process of nutrient solution mixing,due to the differences in nutrient solution concentration,fertilizer absorption method,mixing method and irrigation speed,the process of EC value adjustment has a large time delay and instability,and it is difficult for traditional PID control to achieve good results.Aiming at the above problems,according to the structure of the integrated system of water and fertilizer,the corresponding mathematical model is established,the mathematical model is analyzed in depth,Simulink simulation is carried out,and a set of intelligent EC value control system of nutrient solution with automatic fertilizer mixing characteristics is developed with STM32 microcontroller as the main control chip.In this paper,fuzzy adaptive PID is not only studied in theory in intelligent fertilizer distribution system,but also applied in practice.Through this study,it can be shown that fuzzy adaptive PID can make EC value quickly and accurately stabilize at the set value and meet the actual needs.