Robust passification and control of non-passive systems

This paper addresses the use of passivity-based techniques to obtain robust controller design for non-passive uncertain systems. It extends the previous results on passivity-based control of non-passive systems to include robustness of passification in the presence of plant uncertainty. In particular, sufficient conditions for robust passification are obtained for different passification methods in the presence of various types of plant uncertainties. These conditions can be used either to check the robustness of a controller designed for a nominal plant model or to perform iterative controller design to meet certain robustness criteria. The plant uncertainty models used include additive, multiplicative, and feedback uncertainty. For each of these uncertainty models, conditions for robust passification are derived for three different passification methods, namely, series, feedback, and feedforward passification