H∞ and positive-real control for linear neutral delay systems

This note is concerned with the and positive-real control problems for linear neutral delay systems. The purpose of control is the design of a memoryless state feedback controller which stabilizes the neutral delay system and reduces the norm of the closed-loop transfer function from the disturbance to the controlled output to a prescribed level, while the purpose of positive-real control is to design a memoryless state feedback controller such that the resulting closed-loop system is stable and the closed-loop transfer function is extended strictly positive real. Sufficient conditions for the existence of the desired controllers are given in terms of a linear matrix inequality (LMI). When this LMI is feasible, the expected memoryless state feedback controllers can be easily constructed via convex optimization.