The importance of time delays in control is now well recognized in a wide range of applications (transportation systems, communication networks, teleoperation systems, etc.). However, even if some fundamental results were obtained 40 years ago during the early space explorations (Bellman & Cooke, 1963; Morse, 1976; Kamen, 1978; Manitius & Triggiani, 1978), time-delay systems have actually been ...