A positivity approach to robust controllers analysis and synthesis versus mixed LTI/LTV uncertainties

摘要

The notion of semi-positive realness for complexvalued systems is first defined and characterized through a generalized version of the positive real lemma. This result is then exploited to compute robustness margins versus mixed LTI/LTV real/complex uncertainties. Extensions to fixed-order robust synthesis are also highlighted and a practical algorithm is proposed for the combined design of robust feedback and feedforward controllers. A fighter aircraft example finally illustrates the efficiency and the low conservatism of the scheme.