研究非线性多输入多输出不确定系统在非匹配条件下的鲁棒输出跟踪问题。基于相对阶的假设 ,给出了多输入多输出不确定系统的标准型 ;进而结合反步设计方法和变结构控制方法 ,提出一种非匹配条件下非线性不确定系统鲁棒输出跟踪问题的显式反步变结构控制器设计方法。所给跟踪算法不仅只由不确定性的变化范围直接确定 ,而且有效地克服了现有反步设计算法因隐式递推关系和复杂偏导数计算给实时控制带来的困难 The problem of robust output tracking for non-linear multi-input multi-output uncertain systems under non-matching conditions is studied. Based on the assumption of relative order, a standard model of MIMO-Uncertainty system is given. Then a robust output tracking problem for nonlinear uncertain systems under non-matching conditions is proposed by combining with backstepping design method and variable structure control method Design method of explicit backstepping structure controller. The given tracking algorithm is not only directly determined by the range of uncertainty, but also effectively overcomes the difficulties existing in real-time control due to implicit recursion and complex partial derivatives