ON ROBUSTNESS ANALYSIS VERSUS MIXED LTI/LTV UNCERTAINTIES

In this paper, the notion of semi-positive realness for complex-valued systems is defined and characterized through a generalized version of the positive real lemma. This result provides an efficient state-space method for computing robustness margins versus mixed LTI/LTV real/complex uncertainties, which cannot be easily addressed by more classical gridding-based techniques. The conservatism of this approach is shown to be very low on several examples.