一类输出反馈变结构控制及其应用

An Improved Output Feedback Variable Structure Control

本文研究了只用输出变量构成超平面的一类变结构控制系统．当系统结构满足一定条件时，可以实现输出反馈变结构控制；同时对继电控制算法做了有益的修改，消除了颤振；并设计了某水下航行器航深系统的变结构控制律．仿真研究结果表明了本文方法的有效性，为设计高性能的控制系统提供了一种强有力的方法．

In this paper, the authors present their views on solving two problems cncountered when applying existing sliding mode Variable Structure Control (VSC) methods. One problem is that when attempting to implement output feedback VSC, existing methods fail to stipulate the conditions under which such implementation is feasible. The authors find that these conditions are that, when output hypcrplane is designed in accordance with pole assignment criterion. Eqs. (5)and (7) should be satisfied.The other problem is that the 1990 paper or Hock et al [1] can not eliminate chattering. This paper modifies the method of Hock in Ref. [1] by replacing the sign function of the relay control law in Rcf. [1] with a saturation function whose denominator is that of Ref. [1] plus a small positive quantity δ.Chattering is eliminated by suitablly selecting δ.Simulation results concerning an actual output feedback VSC system indicate that the proposed improvements give not only satisfactory dynamic and steady characteristics, but also strong robustness for the above mentioned system.