Abstract
It is well known that sliding mode control schemes provide robustness to the class of uncertainty acting within channels implicit in the control inputs: the so-called matched uncertainty. However, the unmatched uncertainty will affect the ideal dynamics prescribed by the chosen switching surfaces. This paper develops a control strategy to minimize the effects of the unmatched uncertainty upon the dynamic performance prescribed by the switching surfaces. This is achieved for a subclass of the uncertainty class considered by previous authors. The practical application of the control strategy to the design of a stability augmentation system for a light aircraft is presented. For this problem an ideal performance is well known and it is desirable that these ideal dynamics are exhibited across a wide range of flight conditions without degradation.