The state trajectory of system is chattering , which restrict it ' s actual applications . in the circumstances , the arrival condition and the existence condition have been changed . it is significant to study discrete - time vsc ( dvsc ) to reduce chattering of sliding mode 同时,在离散的情况下,滑动模态的性质、存在条件及其到达条件都已经改变,因此研究离散时间系统变结构控制方法对降低抖振具有重要的理论价值和实际意义。