【作者】 范薇薇；

【导师】 王向东；

【作者基本信息】 沈阳工业大学 ， 控制理论与控制工程， 2010， 硕士

【摘要】 温室是设施农业的重要组成部分,是现代农业发展的重点之一,它能够在多变的自然条件下为作物生长创造一个适宜的环境,从而缩短作物的生长周期,增加经济效益。温度和湿度是温室内最重要的环境因子,它们之间存在非线性强耦合关系,增加了控制难度。针对这一问题,本文研究了一种基于无线传感器网络和模糊PID的智能温室控制系统。温室气候建模是实现温室控制的关键之一。本文首先分析了温室环境中的主要热力学过程,建立了温室的一般机理模型,根据模型反映出的信息,布置传感器网络节点,通过采集信息的计算结果控制适合作物生长的环境因子变化范围。此外,为实现温室主要环境因子的优化调控,本文对温室控制系统进行了整体结构设计并对其硬件进行选型。本文依据对温湿度耦合关系的分析,设计了基于模糊PID温湿度控制器。该控制器是在温湿度有无耦合关系的情况下分别设计的。在不考虑温湿度耦合关系时,控制器的设计原则是依据温湿度的变化速度来调控执行机构操作顺序。而温湿度“伪”解耦控制器是依据湿度变化对温度的影响,将湿度变化时所产生的空气热量值反馈到温度控制的输入量中,使温度在原来设定的基础上得到一定量的补偿后再通过控制器进行调控。同时本文还采用了将模糊控制器与PID控制器相结合,通过阀值进行切换,使系统即有PID控制精度高的特点,又具有模糊控制的灵活、适应性强的特点。利用MATLAB软件仿真,对系统在两种情况下的控制器分别进行了测试,测试结果反映出温湿度解耦控制器动态响应曲线效果更好,超调量小,稳态精度高,能达到理想控制效果。最后,论文对所取得的成果和结论进行了总结,并对下一步工作进行了说明。更多还原

【Abstract】 Greenhouse is an important component of the agricultural facilities, and it is one of the priorities of modern agricultural development. It can change natural conditions for crop growth, create a suitable environment, shorten the crop cycle, and increase economic benefits. Temperature and humidity are the most important environmental factors in the greenhouse, they are strong coupling nonlinear, and increasing the difficulty of control. To solve this control problem, an intelligent greenhouse control system based on WSN and fuzzy PID is designed in the thesis.Greenhouse climate modeling is the key to achieving greenhouse control. First, the main thermodynamic process of the greenhouse environment is analyzed a general mechanism and greenhouse model is established. According to the model, collection nodes are laid. The values of temperature and humidity are calculated by the collecting information in order to get a suitable range of environmental factors of crop growth. For optimizing greenhouse control a structure of the greenhouse control system has been designed and hardware has been selected.Second, according to analysis of coupling relationship of temperature and humidity, controller of temperature and humidity based on fuzzy PID are designed. The controller are respectively designed according to whether the coupling of temperature and humidity or not. Without taking into account coupling between temperature and humidity, the controller design principle is changing the order of the implementing agencies based on the change speed of temperature and humidity. The pseudo decoupling controller of the temperature and humidity is designed according to the impact of humidity change on temperature change; the heat generated by the humidity change will be feedback to the temperature controller, so that the temperature can be compensated. At the same time fuzzy controller and PID controller are combined, through the threshold switching, to promote the accuracy and flexibility of the controller while a PID control or a fuzzy control is adopted only. Then, MATLAB software is used, and the controller in both cases are tested. Test results show that the decoupling controller of the temperature and humidity have better response curves, it is able to achieve the desired control effect.Finally, the results and conclusions are summarized, and the forward works are presented.更多还原