Some trends and tools for the study of time-delay systems

International audienceThis is the text of an invited plenary lecture given by Prof. Jean-Pierre Richard in 1998 at the int. conf. CESA'98. This survey presents some of the recent developments in time-delay systems theory. The general situation of this kind of model in the engineering sciences is recalled and some classes of models are presented. Then, stability and control properties are discussed. Of course, due to the large number of references involved in this field, this overview cannot pretend to exhaustiveness but, the author hopes, contributes to clarify some of the differences between ordinary and hereditary systems