Le cadre des systèmes dynamiques lagrangiens non-réguliers est issu de l'analyse des contacts non-permanents entre des solides parfaitement rigides. Il nous amène à travailler avec des outils mathématiques inhabituels en automatique, comme des vitesses à variations localement bornées, ou des équations différentielles de mesures. L'automatique de ces systèmes dynamiques commence tout juste à apparaître et les théories élémentaires, comme celle de la stabilité au sens de Lyapunov, nécessitent encore d'être établies. Dans ce travail nous proposons donc d'établir les premières bases permettant l'analyse de la stabilité des systèmes dynamiques non-réguliers. Nous montrons qu'il est possible, sous réserve parfois d'hypothèses supplémentaires, d'étendre certains résultats classiques. Nous proposons par exemple un théorème de stabilité au sens de Lyapunov et une extension du théorème de LaSalle pour des systèmes dynamiques décrits par des flots pouvant subir des discontinuités. Dans la cas des systèmes dynamiques lagrangiens non-réguliers, ces résultats de stabilité peuvent s'écrire sous la forme d'un théorème de Lagrange-Dirichlet, en montrant que leur énergie correspond naturellement à une fonction de Lyapunov. Ces résultats sont ensuite appliqués pour l'étude de la stabilité d'une régulation en position et en force d'un bras manipulateur et d'un robot marcheur sans aucune supposition sur l'état des contacts. Nous soulignons également l'intérêt des commandes basées sur la passivité pour les systèmes dynamiques lagrangiens non-réguliers

While the stability theory for systems with bilateral constraints is a well-established field, this monograph represents a systematic study of mechanical systems with unilateral constraints, such as unilateral contact, impact and friction. Such unilateral constraints give rise to non-smooth dynamical models for which stability theory is developed in this work. The book will be of interest to those working in the field of non-smooth mechanics and dynamics.

Le problème de la génération de trajectoires pour les systèmes dynamiques non linéaires sous contraintes non linéaires est considèré en utilisant les techniques de linéarisation par bouclage statique. Après un exposé du formalisme de la linearisation par bouclages statiques, on utilise cette technique pour s'affranchir des problèmes d'intégration numériques pour la génération de trajectoires de grands systèmes non linéaires sous contraintes, l'intégration du système se faisant analytiquement. La technique consiste à optimiser du point de vue local (pas à pas) un critère algébrique (sans contraintes différentielles) par rapport aux contraintes. Les problèmes inhérents à l'approche locale ont été traités pour des recherches de trajectoires de robots manipulateurs. Nous illustrons la méthode par des simulations obtenues avec le modèle du puma 560. Cette méthode peut être utilisée pour la génération de trajectoire en boucle fermée

Born in 1966‚ a generation removed from the counterculture‚ Kevin Mattson came of political age in the conservative Reagan era. In an effort to understand contemporary political ambivalence and the plight of radicalism today‚ Mattson looks back to the ideas that informed the protest‚ social movements‚ and activism of the 1960s. To accomplish its historical reconstruction‚ the book combines traditional intellectual biography—including thorough archival research—with social history to examine a group of intellectuals whose thinking was crucial in the formulation of New Left political theory. These include C. Wright Mills‚ the popular radical sociologist; Paul Goodman‚ a practicing Gestalt therapist and anarcho-pacifist; William Appleman Williams‚ the historian and famed critic of "American empire"; Arnold Kaufman‚ a "radical liberal" who deeply influenced the thinking of the SDS. The book discusses not only their ideas‚ but also their practices‚ from writing pamphlets and arranging television debates to forming left-leaning think tanks and organizing teach-ins protesting the Vietnam War. Mattson argues that it is this political engagement balanced with a commitment to truth-telling that is lacking in our own age of postmodern acquiescence. Challenging the standard interpretation of the New Left as inherently in conflict with liberalis‚ Mattson depicts their relationship as more complicated‚ pointing to possibilities for a radical liberalism today. Intellectual and social historians‚ as well as general readers either fascinated by the 1960s protest movements or actively seeking an alternative to our contemporary political malais‚ will embrace Mattson’s book and its promise to shed new light on a time period known for both its intriguing conflicts and its enduring consequences.

Did New Left activists have an opportunity to start a revolution that they simply could not bring off? Was their rejection of conventional forms of political organization a fatal flaw or were the apparent weaknesses of the movement -- the lack of central authority, the distrust of politics -- actually hidden strengths? Wini Breines traces the evolution of the New Left movement through the Free Speech Movement, Students for a Democratic Society (SDS), and SDS's community organization projects. For Breines, the movement's goal of participatory decision-making, even when it was not achieved, made up for its failure to take practical and direct action. By the late 1960s, antiwar activism contributed to the decline of the New Left, as the movement was flooded with new participants who did not share the founding generation's political experiences or values. Originally published in 1982, Wini Breines's classic work now includes a new preface in which she reassesses, and for the most part affirms, her initial views of the movement. She argues that the movement remains effective in the midst of radical changes in activist movements. Breines also summarizes and evaluates the new and growing scholarship on the 1960s. Her provocative analysis of the New Left remains important today.

This 1970 study examines the implications of empirical studies in the social sciences with reference to various strands of American and British democratic theory. In presenting his case Professor Thompson provides an extremely valuable critical synthesis of a very large body of theoretical and empirical literature in this field. He weaves together in an original way the works of more than a dozen twentieth-century political theorists and several hundred empirical studies by political scientists, sociologists and social psychologists.