Parallel Manipulators

In recent years, parallel kinematics mechanisms have attracted a lot of attention from the academic and industrial communities due to potential applications not only as robot manipulators but also as machine tools. Generally, the criteria used to compare the performance of traditional serial robots and parallel robots are the workspace, the ratio between the payload and the robot mass, accuracy, and dynamic behaviour. In addition to the reduced coupling effect between joints, parallel robots bring the benefits of much higher payload-robot mass ratios, superior accuracy and greater stiffness; qualities which lead to better dynamic performance. The main drawback with parallel robots is the relatively small workspace. A great deal of research on parallel robots has been carried out worldwide, and a large number of parallel mechanism systems have been built for various applications, such as remote handling, machine tools, medical robots, simulators, micro-robots, and humanoid robots. This book opens a window to exceptional research and development work on parallel mechanisms contributed by authors from around the world. Through this window the reader can get a good view of current parallel robot research and applications

Augmentation de la taille de l’espace de travail opérationnel des robots parallèles en traversant les singularités de Type 2 :Génération de trajectoires optimales et commande avancée

In order to increase the size of the operational workspace of parallel robots (largely reduced by the presence of singularities), the approach proposed in this thesis consists of directly moving a mechanism through those singularities.To do so, the conditions of degeneracy of the dynamic model of parallel robots are first studied. From those conditions, it is possible to create criteria that ensure the non-degeneracy of the mechanism in a singular configuration. This allows the planning of trajectories that go from one aspect of the workspace to another through a singularity, and without anydegeneracy of the dynamic model. In order to track those trajectories, a multi-model computed torque control is presented, coupled with an optimal trajectory planning strategy.Every development presented have been validated in simulation and experimentally on a prototype of a five-bar mechanism designed and manufactured during the thesis.Afin d’augmenter la taille de l’espace de travail opérationnel des robots parallèles (largement réduit par la présence de singularités), cette thèse propose une approche consistant à traverser ces singularités.Pour permettre cette traversée, les conditions de dégénérescence du modèle dynamique des mécanismes parallèles sont d’abord étudiées. Cette étude permet de mettre en place des conditions de non dégénérescence sous forme de critères. En planifiant une trajectoire respectant ces critères, un mécanisme parallèle peut théoriquement traverserune singularité sans que les efforts ne divergent. Un contrôleur basé sur une commande en couples-calculés multi-modèle et dédié à la traversée de singularité, couplé avec une stratégie de planification de trajectoire optimale est par la suite proposé. L’ensemble des travaux présentés est validé en simulation puis expérimentalement sur un prototype de mécanismes à cinq barres développé et conçu durant la thèse

Vibration, Control and Stability of Dynamical Systems

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”