Robustness of uncertain systems in the absence of matching assumptions

We consider a class of uncertain dynamical systems containing uncertain elements. These may be due to model-parameter uncertainty, input disturbance and measurement noise. We require no a priori information on the uncertain elements except that their restraint sets are assumed to be known and compact. This paper describes a general approach for designing controls to assure practical stability in the absence of matching assumptions (which most previous results have needed). The result is applicable to non-linear systems. A specialization to linear systems is then given and a comparison is made with previous work.