毕业设计论文

基于Matlab的恒温箱温度控制系统设计与仿真

摘 要 恒温箱在工业生产和科学研究中有着重要的作用，因此设计一个合适的温度控制系统有着重要的意义，而恒温箱的温度控制系统比较复杂，是一个大时滞、时变、非线性系统，很难用数学方法建立精确的数学模型。 目前主要采用经典控制、智能控制和两种控制算法相结合的控制算法对恒温箱的温度控制系统进行控制。

在本文中选定二阶纯滞后环节为控制对象的数学模型，对其分别采用PID控制算法，模糊控制算法和模糊PID算法对恒温箱进行控制，并用Matlab对各算法进行仿真比较分析。通过对这几种算法的仿真与研究，发现PID整定好的参数不能长期适应系统模型，需要不断对控制器参数进行整定，才能达到较好的控制效果；模糊控制不依赖于系统的精确模型，是解决不确定性系统的一种有效途径，但控制精度不高，且量化因子和比例因子确定后，其适应能力有限制；而模糊PID控制方法具备了模糊控制和PID控制各自的优点，同时具有很强的鲁棒性和适应能力。

关键词 大时滞系统，PID控制，模糊控制，模糊PID控制

ABSTRACT

As thermostat plays an important role in the production and scientific research, so designing a suitable temperature control system important significance. The thermostat's temperature control system is complex, and is a large time lag, time-varing, nonlinear system, then it is difficult to establish an accurate mathematical model. Currently the classical control, inligent control and their combined control algorithm are main used for control the temperature control system.

This paper selects second-order lag model for the control object, and uses PID

control algorithm, fuzzy control algorithm and fuzzy PID algorithm to control thermostat and uses Matlab software for the simulation comparative analysis. By studying several simulation we found that PID algorithm arranges the parameter cannot adapt a long time, and it need unceasingly be carried on the adjustment and achieve the anticipated effect. Fuzzy control does not depend on the precise object model and is an effective way to solve the uncertainty. But the control accuracy is not quantifiable factor and scale factor is determined ,its adaptable ability is restricted. As fuzzy PID control algorithm ,it not only combines the fuzzy control and PID control with their respective advantages, but also , PID control, Fuzzy control, Fuzzy PID control

1.绪论 ........................................ 错误！未定义书签。 1.1选题的目的、意义 ......................................... 2 1.2对本课题涉及问题的研究现状 ............................... 3

1.2.1经典控制 ................................................................ 3

1.2.2智能控制 ................................................................ 4 1.2.3结论 .................................................................... 5

1.3主要解决的问题 ........................................... 6 2.PID控制及仿真 ................................................ 6 2.1微分先行PID算法[7] ...................................... 7 2.2参数辨识 ................................................. 7 2.3PID参数的整定 ............................................ 8

2.3.1PID参数的特点 ........................................................... 8 2.3.2ZN经验公式法 ............................................................ 9

2.4PID算法仿真 .............................................. 9 3.1模糊控制基本原理[11] ..................................... 9

3.1.1模糊控制基本思想 ........................................................ 9 3.1.2模糊控制器的基本结构 .................................................... 9 3.1.3模糊控制的特点 ......................................................... 11

3.2模糊控制器的设计[12] .................................... 12 3.3温度模糊控制器的设计 .................................... 13

3.3.1控制器结构 ............................................................. 13 3.3.2模糊子集的选取 ......................................................... 13 3.3.3模糊规则的确定 ......................................................... 14 3.3.4模糊推理 ............................................................... 15

3.4模糊控制仿真 ............................................ 16

3.4.1模糊控制仿真 ........................................................... 16

4.模糊PID控制及仿真 ........................................... 16 4.1模糊PID控制器结构 ...................................... 17 4.2模糊控制器的设计 ........................................ 17