Kinematic Analysis of a Serial - Parallel Machine Tool: the VERNE machine

The paper derives the inverse and the forward kinematic equations of a serial - parallel 5-axis machine tool: the VERNE machine. This machine is composed of a three-degree-of-freedom (DOF) parallel module and a two-DOF serial tilting table. The parallel module consists of a moving platform that is connected to a fixed base by three non-identical legs. These legs are connected in a way that the combined effects of the three legs lead to an over-constrained mechanism with complex motion. This motion is defined as a simultaneous combination of rotation and translation. In this paper we propose symbolical methods that able to calculate all kinematic solutions and identify the acceptable one by adding analytical constraint on the disposition of legs of the parallel module

Workspace Analysis of the Parallel Module of the VERNE Machine

The paper addresses geometric aspects of a spatial three-degree-of-freedom parallel module, which is the parallel module of a hybrid serial-parallel 5-axis machine tool. This parallel module consists of a moving platform that is connected to a fixed base by three non-identical legs. Each leg is made up of one prismatic and two pairs of spherical joint, which are connected in a way that the combined effects of the three legs lead to an over-constrained mechanism with complex motion. This motion is defined as a simultaneous combination of rotation and translation. A method for computing the complete workspace of the VERNE parallel module for various tool lengths is presented. An algorithm describing this method is also introduced

Workspace and Kinematic Analysis of the VERNE machine

This paper describes the workspace and the inverse and direct kinematic analysis of the VERNE machine, a serial/parallel 5-axis machine tool designed by Fatronik for IRCCyN. This machine is composed of a three-degree-of-freedom (DOF) parallel module and a two-DOF serial tilting table. The parallel module consists of a moving platform that is connected to a fixed base by three non-identical legs. This feature involves (i) a simultaneous combination of rotation and translation for the moving platform, which is balanced by the tilting table and (ii) workspace whose shape and volume vary as a function of the tool length. This paper summarizes results obtained in the context of the European projects NEXT ("Next Generation of Productions Systems")

Multi-Objective Design Optimization of the Leg Mechanism for a Piping Inspection Robot

This paper addresses the dimensional synthesis of an adaptive mechanism of contact points ie a leg mechanism of a piping inspection robot operating in an irradiated area as a nuclear power plant. This studied mechanism is the leading part of the robot sub-system responsible of the locomotion. Firstly, three architectures are chosen from the literature and their properties are described. Then, a method using a multi-objective optimization is proposed to determine the best architecture and the optimal geometric parameters of a leg taking into account environmental and design constraints. In this context, the objective functions are the minimization of the mechanism size and the maximization of the transmission force factor. Representations of the Pareto front versus the objective functions and the design parameters are given. Finally, the CAD model of several solutions located on the Pareto front are presented and discussed.Comment: Proceedings of the ASME 2014 International Design Engineering Technical Conferences \& Computers and Information in Engineering Conference, Buffalo : United States (2014

Singularity Analysis of Limited-dof Parallel Manipulators using Grassmann-Cayley Algebra

This paper characterizes geometrically the singularities of limited DOF parallel manipulators. The geometric conditions associated with the dependency of six Pl\"ucker vector of lines (finite and infinite) constituting the rows of the inverse Jacobian matrix are formulated using Grassmann-Cayley algebra. Manipulators under consideration do not need to have a passive spherical joint somewhere in each leg. This study is illustrated with three example robot

Contribution à l'étude cinématique et dynamique des machines parallèles

This thesis deals with the kinematic and dynamic modelling of limited degree-of-freedom parallel robots. These robots with less than six degrees of freedom are able to carry out several industrial tasks. The main reason of using such robots is to reduce the production costs by using less legs and motors. However, in some cases, these structures can produce a complex motion defined as a simultaneous combination of translation and rotation of the moving platform, which is the case of the Verne parallel module having three translation degrees of freedom. The modelling of this type of robots can prove to be complicated. This report includes five chapters. In the first chapter, a classification of parallel architectures is presented and a state of the art on important notions on kinematics and design of manipulators is exposed. The second and the third chapters are devoted to the kinematic modelling, serial singularity analysis and workspace calculation of the Verne machine. The fourth chapter deals with parallel singularity analysis of limited degrees of freedom robots using Grassmann-Cayley algebra. The geometrical conditions of existence of parallel singularities of three classes of parallel manipulators are found. Finally, the fifth chapter covers the dynamic modelling of limited degree-of-freedom parallel manipulators. A general method based on the Newton-Euler algorithm is developed. The proposed method takes in consideration all the dynamics of these robots including the legs dynamics as well as the mobile platform dynamics.Les travaux présentés dans cette thèse portent sur l’étude cinématique et dynamique des robots parallèles à mobilités restreintes. Ces robots à moins de 6 degrés de liberté permettent d’effectuer de multiples tâches demandées par l’industrie. La raison principale de l’utilisation de ces robots est la volonté de réduire le coût en utilisant moins de jambes et moins de moteurs. Cependant, ces structures peuvent dans certains cas produire un mouvement de la plate-forme contraint par un couplage entre la position et l’orientation comme pour le module parallèle de la machine Verne ayant trois degrés de liberté de translation. Dans ce cas, la modélisation peut s’avérer compliquée. Ce mémoire comporte cinq chapitres. Dans le premier chapitre, une classification des architectures parallèles est présentée et des notions importantes liées à la cinématique et à la conception des manipulateurs sont exposées. Les deuxième et troisième chapitres sont consacrés à la modélisation géométrique, à l’étude des singularités sérielles et au calcul de l’espace de travail de la machine Verne. Le quatrième chapitre traite les singularités parallèles des manipulateurs à mobilités restreintes en utilisant l’algèbre de Grassmann-Cayley. Les conditions géométriques d’existence des singularités pour trois classes de manipulateurs sont trouvées. Les chaînes de ces manipulateurs transmettent des forces et/ou couples à la plate-forme mobile. Finalement, le cinquième chapitre concerne la modélisation dynamique des manipulateurs à mobilités restreintes. Une méthode générale basée sur les algorithmes de type Newton-Euler est développée. La méthode proposée prend en compte la dynamique des jambes et de la plate-forme. Nous obtenons ainsi des modèles dynamiques complets de ces robots

Singularity Analysis of Lower-Mobility Parallel Manipulators Using Grassmann-Cayley Algebra

This paper introduces a methodology to analyze geometrically the singularities of manipulators, of which legs apply both actuation forces and constraint moments to their moving platform. Lower-mobility parallel manipulators and parallel manipulators, of which some legs do not have any spherical joint, are such manipulators. The geometric conditions associated with the dependency of six Pl\"ucker vectors of finite lines or lines at infinity constituting the rows of the inverse Jacobian matrix are formulated using Grassmann-Cayley Algebra. Accordingly, the singularity conditions are obtained in vector form. This study is illustrated with the singularity analysis of four manipulators

TALP-UPC at TREC 2005: Experiments using voting scheme among three heterogeneous QA systems

This paper describes the experiments of the TALP-UPC group for factoid and ’other’ (definitional) questions at TREC 2005 Main Question Answering (QA)task. Our current approach for factoid questions is based on a voting scheme among three QA systems: TALP-QA (our previous QA system), Sibyl (a new QA system developed at DAMA-UPC and TALP-UPC), and Aranea (a web-based data-driven approach). For defitional questions, we used two different systems: the TALP-QA Definitional system and LCSUM (a Summarization-based system). Our results for factoid questions indicate that the voting strategy improves the accuracy from 7.5% to 17.1%. While these numbers are low (due to technical problems in the Answer Extraction phase of TALP-QA system) they indicate that voting is a succesful approach for performance boosting of QA systems. The answer to definitional questions is produced by selecting phrases using set of patterns associated with definitions. Its results are 17.2% of F-score in the best configuration of TALP-QA Definitional system.Postprint (published version

Spontaneous regression of pulmonary alveolar proteinosis: a case report

Relatamos o caso de uma mulher de 21 anos com história de seis meses de dispneia progressiva, tosse seca e perda de peso. A tomografia computadorizada de alta resolução revelou padrão de pavimentação em mosaico com áreas focais poupadas. A paciente foi submetida a biópsia pulmonar transbrônquica, que confirmou o diagnóstico de proteinose alveolar. Dois anos depois, sem tratamento, houve importante melhora das opacidades pulmonares