Robust stability condition for a class of time-delay plants with uncertainty

In this paper, we consider the robust stability condition for single-input/single-output time-delay plants with new class of uncertainties. First of all, we define a class of uncertainties to be considered. The necessary and sufficient robust stability condition for time-delay plants with such class of uncertainties is presented. The relation between the time-delay plant and the nominal time-delay plant that is included in such class of uncertainties is clarified. By using this relation, we will show the necessary and sufficient robust stability condition for the time-delay plants with varying number of right half plane poles.