一类死区非线性系统的自适应模糊控制设计  

Adaptive fuzzy control design for a class of dead-zone nonlinear systems

作　　者：李平[1] 金福江[1] 方慧娟[1] 

机构地区：[1]华侨大学信息科学与工程学院,福建厦门361021

出　　处：《计算机与应用化学》2011年第7期875-878,共4页Computers and Applied Chemistry

基　　金：泉州市科技计划重大项目(2008ZD14-21);华侨大学高层次人才科研启动费项目(10BS108;09BS617);福建省自然科学基金青年创新项目(2009J05147)

摘　　要：为了实现对具有时变摄动死区非线性系统的跟踪控制,本文提出了一种基于自适应模糊逼近器的Backstepping控制方法。该方法通过将死区特性合理分解,并将自适应模糊逼近器嵌入到Backstepping设计步骤中,逐步递推得到控制律。所提出的控制方法适用于高阶非线性系统,并且不要求被控系统满足匹配条件;所采用的模糊逼近器是非线性参数化的,亦即不要求其模糊基函数是完全确定已知的,从而降低了对先验知识的依赖性。为了得到未知参数的自适应律,本文先应用Taylor级数展开式将具有非线性关系的未知参数相互分离,使其呈现线性关系,然后根据Lyapunov稳定性定理给出在线可调参数的自适应律。此外,所设计的自适应律是对与未知参数向量的范数相关的变量进行在线调节,这样可以有效减少需要在线调节的参数数量,从而降低了控制器的在线计算负担,提高了系统的响应速度和控制精度。本文给出的控制设计能够有效地克服死区特性对系统性能的影响,使得闭环系统所有信号均指数收敛到原点的指定邻域内,系统输出可以按给定的精度跟踪参考信号。最后,本文用一个仿真实例验证了所给控制方法的有效性。A control method based on adaptive fuzzy approximaturs is proposed in this paper to realize the tracking control problem for a class of time-varying and disturbed dead-zone nonlinear systems. By reasonable decomposing the dead-zone, this method derives the control law by imbedding fuzzy approximators into Backstepping steps. The proposed method is applicable to high-order nonlinear systems, and the controlled systems are not required to satisfy the matching conditions. The adopted fuzzy approximators are nonlinearly parameterized, which do not their basis functions completely determined. In order to obtain the adaptive laws, Taylor series expansion is employed to separate the nonlinear unknown parameters. And then the adaptive laws are designed on the basis of Lyapunov Stability Theory. Besides, the control laws are designed to adjust the norm of the unknown parameters, which can reduce the on-line computation burden and improve the control speed and precision. The control design presented in this paper can overcome the influences caused by the dead-zone. All closed-loop signals are guaranteed to eonverge to a small neighborhood of origin, and the output can track the reference signal within a given precision. Finally, A simulation example is given to show the effectiveness of the control method.

关 键 词：死区 非线性系统 自适应模糊逼近 BACKSTEPPING设计 

分 类 号：TQ015.9[化学工程]