Sufficient conditions for the controllability of linear descriptor systems with both time‐varying structured and unstructured parameter uncertainties

In this paper, under assumptions that the linear nominal descriptor system is regular and controllable, some sufficient conditions are proposed to preserve the assumed properties when both time‐varying structured and unstructured parameter uncertainties are added into the nominal descriptor system. The corresponding results for the dual observability robustness problems are straightforward extensions. It is shown that the proposed sufficient conditions are the generalized versions of the results reported recently in the literature.