摘要:
提出一种新颖的基于DNA的进化算法(DNA-EA)来自动设计一类Trakagi-Sugeno
(TS)模糊控制器.TS模糊控制器采用带有线性规则后项的TS模糊规则,连续输
入模糊集,Zadeh模糊逻辑和常用的重心反模糊器.TS模糊控制器被证明是带有可变增
益的非线性PI控制器.DNA-EA被用于自动获取TS模糊规则,并同时优化模糊规则前
项和后项中的设计参数.DNA-EA采用由生物DNA结构启发得到的DNA编码方法来编
码模糊控制器的设计参数.在DNA-EA中,引入了受微生物进化现象启发的基因转移和细
菌变异操作.另外,也引入了基于DNA遗传操作的框构变异操作.DNA编码方法非常适
合于复杂知识的表达,基于基因水平的遗传操作也很容易引入到DNA-EA中.染色体的长
度是可变的,且可插入或删除部分碱基序列.作为示例,给出了采用DNA-EA来自动设计
TS模糊控制器用于控制一类非线性系统的方法.DNA-EA能自动地构造模糊控制器.计
算机仿真结果表明,DNA-EA是有效的,且优化得到的模糊控制器是满意的.
Abstract:
In this paper, we propose a new approach to DNA-based evolutionary algorithm
(DNA-EA) to design automatically a class of Takagi-Sugeno (TS) fuzzy controllers.
The fuzzy controllers employ TS fuzzy rules with linear consequent, continuous input
fuzzy sets, Zadeh fuzzy logic AND operation, and the widely-used centroid defuzzier.
The fuzzy controllers are proved to be nonlinear PI controllers with variable gains. The
fuzzy rules are automatically discovered, and the design parameters in the input fuzzy
sets and the linear rule consequent are optimized simultaneously by the DNA-EA. The
DNA-EA uses the DNA encoding method stemmed from the structure of the biological
DNA to encode the design parameters of the fuzzy controllers. The gene transfer opera-
tion and bacterial mutation operation inspired by a microbial evolution phenomenon are
introduced into the DNA-EA. Moreover, frameshift mutation operations based on the
DNA genetic operations are also used in the DNA-EA. Our encoding method is suitable
for complex knowledge representation, and is easy for the genetic operations at gene level
to be introduced into the DNA-EA. The length of the chromosome is variable and it is
easy to insert and delete parts of the chromosome. As a demonstration, we show how to
implement the new method to design automatically a TS fuzzy controller in the control
of a nonlinear system. The fuzzy controller can be automatically constructed by the
DNA-EA. Computer simulation results indicate that the new method is effective and the
designed fuzzy controller is satisfactory.