带前置滤波器的MRAC系统的变结构控制

Variable structure control for MRAC systems with feedforward filter

中文关键词  未建模动态  前置滤波器  变结构控制  全局稳定性

英文关键词  unmodeled dynamics  feedforward filter  variable structure control  global stability

中文摘要

      变结构控制对参数不确定性,外部干扰和未建模动态具有鲁棒性,并被应用到鲁棒模型参考自适应系统.其缺点是易产生抖振.本文设计一种带有前置滤波器的变结构控制器,改善系统动态性能并消除了抖振.前置滤波器使带有符号函数的控制切换产生连续可测信号,实际控制律是光滑的.控制器设计和不确定性估计中引入辅助信号和带有记忆功能的正规化信号,适当选取控制器参数,所设计的控制器保证了闭环系统稳定性和任意小的跟踪误差.仿真结果表明该算法是有效的.

英文摘要

      The variable structure control (VSC) scheme is robust to parameter uncertainty, external disturbance, and un-modeled dynamics, and it is widely applied to designing the robust model reference adaptive control (MRAC) systems. The main drawback of VSC is the phenomena of chattering. To improve system performance and to eliminate chattering, a new VSC with feedforward filter is designed in the paper. The proposed stable feedforward filter makes the control switching with sign functions to produce a continuous and measurable signal so that the actual control law is smooth. The auxiliary signals and normalized signals with memory functions are introduced to the controller design and the estimation of uncertainties. With a suitable choice of controller parameters, it is shown that even when the unmodeled dynamics exists, the proposed VSC guarantees the closed-loop global stability and arbitrary smallness of the tracking error. Simulation validates the proposed VSC scheme.