A unified approach to time-delay system control: robust and gain-scheduled

This paper considers the output-feedback performance control of a large class of uncertain linear time-delay systems, that is, systems where (time varying) dynamical and parameter uncertainties are explicitly modeled. For a controller with a given structure, we propose design methods based on both time-delay independent and time-delay dependent conditions. Depending on the selected controller structure, these conditions can be either convex or non-convex. All the conditions are directly derived from a general result. In contrast with most time-delay control methods, our results are developed in an input-output framework. Our conditions recover and generalize previous ones