液位模糊控制系统的设计【毕业作品】

BI YE SHE JI

（20 届）

液位模糊控制系统的设计

所在学院

专业班级自动化

学生姓名学号

指导教师职称

完成日期年月

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摘要

液位控制系统广泛存在于各个领域，是工业过程控制中的典型控制之一，液位控制早期运用PID控制方法实现。常规的PID控制器具有无静态误差、高可靠行、算法简单等优点。它的设计核心是整定参数，对于确定性的被控对象通过设定合适的PID控制器的三个参数，可以获得比较理想的控制效果。但由于实际控制系统具有时变性、多变量、大滞后等特点，且在控制过程中会受到各种干扰因素的影响，要建立精确的数学模型很困难，也就不能达到预期效果。

近些年来，在很多控制过程中模糊控制都取得了成功，模糊控制器具有不依赖被控对象数学模型，适应性强的优点，在许多无法建立精确数学模型的复杂系统中表现出了其优越性，不仅获得了较好的控制效果，而且又能简化系统的设计。因此，模糊控制在水箱液位控制系统中就成为较好的选择。本文利用模糊控制理论设计一水箱水位模糊控制器，具体给出了系统设计方案。首先详细的介绍了模糊控制的基本原理及模糊控制器的相关知识，其次讲述了对系统进行模糊控制的具体设计内容，在此基础上提出对水箱水位进行模糊控制的方案。最后，充分利用MATLAB的模糊逻辑工具箱和Simulink相结合的功能得到实际液位跟踪给定液位的曲线，仿真结果证实水箱液位模糊控制系统能够获得良好的控制效果。

关键词：液位控制；模糊控制；MATLAB；Simulink

Abstract

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Liquid level control system exists in each field extensively and is one of the typical control in industrial process control, the liquid level control most used PID control method in the early days. Conventional PID controller has lots of strong points, for instance, it has no static error, its algorithm is simple and it is reliable. The heart of its design is setting parameters; the certainty object can achieve satisfactory control effects through proper setting three parameters of PID. But the practical control systems have the characteristics of time-dependence, nonlinear, large lag and they will be influenced by various kinds of interference factors, so it is difficult to set up accurate mathematics model, then it is not possible to achieve the desired results.

In the recent years, fuzzy control has achieved success in many control process. Fuzzy controller has outstanding merits that do not rely on mathematics model of object and whose adapting ability is strong, it shows its superiority in many complex systems which have no accurate mathematics model. It not only wins the better control results, but also can reduce system design. Therefore, control fuzzily become better choice on water tank level control system. This text designs a water tank level fuzzy control system according to the fuzzy control theory and puts forward a design scheme specifically. Firstly, it introduces the fuzzy control theory and the related knowledge of the fuzzy controller. Then, it describes the detailed design things for the system design, and proposes a fuzzy control scheme for the liquid level of the water tank on this basis. At last, the system has also fully utilized the function that the fuzzy logic toolbox of MATLAB combines with SIMULINK, and obtains the curve of the actual level tracking the desired level. Simulation results show that the water tank fuzzy control system can possess good control performance.

Keywords: liquid level control; fuzzy control; MATLAB; Simulink

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