Robust controller synthesis for uncertain time-varying systems

In this paper we develop and present new convex synthesis conditions for robust performance in linear time-varying systems, subject to time-varying perturbations. In particular, these results are exact for sensitivity minimization in the presence of multiplicative perturbations. The methods apply to a number of additional robust performance problems and are always both necessary and sufficient when the system plant is periodic. Otherwise, the conditions provided are always sufficient, and a controller can be directly constructed when this condition holds.