控制方向未知的SISO非仿射系统间接自适应模糊输出反馈控制

针对一类单输入单输出(SISO)非仿射非线性系统控制方向未知时出现的控制器奇异问题,提出了一种间接自适应模糊控制方案.利用中值定理将非仿射系统转化为仿射系统,通过模糊逻辑系统逼近该仿射系统中的未知函数,并构造模糊控制器,同时利用Lyapunov稳定性定理设计自适应律,最终克服了控制器的奇异问题;在此基础上,通过构造观测器估计跟踪误差,设计输出反馈自适应模糊控制器,解决了状态不可测时系统控制器设计难题,采用Lyapunov稳定性定理证明控制器能使得跟踪误差收敛同时闭环系统所有信号均有界.仿真结果验证了所设计控制方案的可行性与有效性.

Indirect adaptive fuzzy output-feedback controller for a SISO nonaffine system with unknown control direction

To deal with the singularity problem of the controller for the single-input single-output (SISO) nonaffine nonlinear system when the control direction is unknown, we propose an indirect adaptive fuzzy control scheme. The nonaffine nonlinear system is first transformed into an affine system by using the mean value theory, and then a fuzzy logic system (FLS) is utilized to approximate the unknown functions in the affine system. Using Lyapunov stability theorem, we derive the adaptive laws for FLS parameters. The fuzzy controller which can remove the singularity problem is designed. On the basis of the aforementioned work and by designing an observer to estimate the tracking error, we construct an adaptive fuzzy output-feedback controller. The difficulty in controller design when the system state is unavailable has been overcome. The Lyapunov stability theory is utilized to prove that the tracking error is asymptotic convergent and all signals in closed-loop system are bounded. Finally, the simulation results demonstrate the feasibility and validity of the proposed control schemes.