Ara es mostren els items 1-20 de 59

  • A bilinear formulation for the motion planning of non-holonomic parallel orienting platforms 

    Grosch Obregon, Patrick John; Thomas, Federico (Institute of Electrical and Electronics Engineers (IEEE), 2013)
    Text en actes de congrés
    Accés obert
    This paper deals with the motion planning problem for parallel orienting platforms with one non-holonomic joint and two prismatic actuators which can maneuver to reach any three-degree-of-freedom pose of the moving platform. ...
  • A coordinate-free approach to tracing the coupler curves of pin-jointed linkages 

    Rojas Libreros, Nicolás Enrique; Thomas, Federico (ASME PRESS, 2011)
    Text en actes de congrés
    Accés restringit per política de l'editorial
    In general, high-order coupler curves of plane mechanisms cannot be properly traced by standard predictor-corrector algorithms due to drifting problems and the presence of singularities. Instead of focusing on finding ...
  • A distance geometry approach to the singularity analysis of 3R robots 

    Thomas, Federico (ASME PRESS, 2015)
    Article
    Accés restringit per política de l'editorial
    This paper shows how the computation of the singularity locus of a 3R robot can be reduced to the analysis of the relative position of two coplanar ellipses. Since the relative position of two conics is a projective ...
  • A distance-based formulation of the octahedral manipulator kinematics 

    Rojas Libreros, Nicolás Enrique; Borràs Sol, Júlia; Thomas, Federico (2010)
    Text en actes de congrés
    Accés obert
    In most practical implementations of the Gough-Stewart platform, the octahedral form is either taken as it stands or is approximated. The kinematics of this particular instance of the Gough-Stewart platform, commonly known ...
  • A family of quadratically-solvable 5-SPU parallel robots 

    Borràs Sol, Júlia; Thomas, Federico; Torras, Carme (2010)
    Text en actes de congrés
    Accés obert
    A 5-SPU robot with collinear universal joints is well suited to handling an axisymmetric tool, since it has 5 controllable DoFs and the remaining one is a free rotation around the tool. The kinematics of such a robot having ...
  • A linear relaxation technique for the position analysis of multi-loop linkages 

    Porta Pleite, Josep Maria; Ros Giralt, Lluís; Thomas, Federico (2008)
    Report de recerca
    Accés obert
    This report presents a new method able to isolate all configurations that a multi-loop linkage can adopt. We tackle the problem by providing formulation and resolution techniques that fit particularly well together. The ...
  • A linear relaxation technique for the position analysis of multiloop linkages 

    Porta Pleite, Josep Maria; Ros Giralt, Lluís; Thomas, Federico (2009)
    Article
    Accés obert
    This paper presents a new method to isolate all configurations that a multiloop linkage can adopt. The problem is tackled by means of formulation and resolution techniques that fit particularly well together. The adopted ...
  • A matrix-based approach to the image moment problem 

    Martínez Bauzà, Judit; Porta Pleite, Josep Maria; Thomas, Federico (2006-11)
    Article
    Accés obert
    An image can be seen as an element of a vector space and hence it can be expressed in as a linear combination of the elements of any non necessarily orthogonal basis of this space. After giving a matrix formulation of this ...
  • A one-motor full-mobility 6-PUS manipulator 

    Grosch Obregon, Patrick John; Gregorio, Raffaele di; Thomas, Federico (Springer, 2010)
    Text en actes de congrés
    Accés obert
    This paper presents the feasibility study of an under-actuated parallel manipulator with 6-PUS topology, destined to handle work-tables in CNC machine tools. The proposed device exploits the fact that, in such an application, ...
  • A reconfigurable 5-DoF 5-SPU parallel platform 

    Borràs Sol, Júlia; Thomas, Federico; Ottaviano, Erika; Ceccarelli, Marco (2009)
    Text en actes de congrés
    Accés obert
    This paper presents a 5-SPU platform whose base leg attachments can be easily reconfigured, statically or dynamically, without altering its singularity locus. This permits to adapt the platform’s geometry to particular ...
  • A robust forward kinematics analysis of 3-RPR planar platforms 

    Rojas Libreros, Nicolás Enrique; Thomas, Federico (Springer Verlag, 2010)
    Text en actes de congrés
    Accés obert
    The standard forward kinematics analysis of 3-RPR planar parallel platforms boils down to computing the roots of a sextic polynomial. There are many different ways to obtain this polynomial but all of them include exceptions ...
  • A short account of Leonardo Torres' endless spindle 

    Thomas, Federico (2008)
    Article
    Accés restringit per política de l'editorial
    At the end of the 19th century, several analog machines had been proposed for solving algebraic equations. These machines – based not only on kinematics principles but also on dynamic or hydrostatic balances, electric or ...
  • A space decomposition method for path planning of loop linkages 

    Porta Pleite, Josep Maria; Cortes, Juan; Ros Giralt, Lluís; Thomas, Federico (IEEE, 2007)
    Text en actes de congrés
    Accés obert
    This paper introduces box approximations as a new tool for path planning of closed-loop linkages. Box approximations are finite collections of rectangloids that tightly envelop the robot's free space at a desired resolution. ...
  • A unified position analysis of the Dixon and the generalized Peaucellier linkages 

    Rojas Libreros, Nicolás Enrique; Dollar, Aaron M.; Thomas, Federico (2015-12-01)
    Article
    Accés restringit per política de l'editorial
    This paper shows how, using elementary Distance Geometry, a closure polynomial of degree 8 for the Dixon linkage can be derived without any trigonometric substitution, variable elimination, or artifice to collapse mirror ...
  • A wire-based active tracker 

    Andrade-Cetto, Juan; Thomas, Federico (IEEE, 2008)
    Article
    Accés obert
    Wire-based tracking devices are an affordable alternative to costly tracking devices. They consist of a fixed base and a platform, attached to the moving object, connected by six wires whose tension is maintained along the ...
  • A wrench-sensitive touch pad based on a parallel structure 

    Frigola Alcalde, Roger; Ros Giralt, Lluís; Roure Fernández, Francisco; Thomas, Federico (2008)
    Text en actes de congrés
    Accés obert
    Many different robotic in-parallel structures have been conceived as six-component force sensors. In general, they perform well for most applications but, when accuracy is a must, two main limitations arise. First, in most ...
  • A wrench-sensitive touch pad based on a parallel structure 

    Frigola Alcalde, Roger; Ros Giralt, Lluís; Roure Fernández, Francisco; Thomas, Federico (IEEE, 2008)
    Text en actes de congrés
    Accés obert
    Many different robotic in-parallel structures have been conceived as six-component force sensors. In general, they perform well for most applications but, when accuracy is a must, two main limitations arise. First, in most ...
  • Analysing the singularities of 6-SPS parallel robots using virtual legs 

    Borràs Sol, Júlia; Thomas, Federico; Torras, Carme (LIRMM, 2008)
    Text en actes de congrés
    Accés obert
    A virtual leg in a 6-SPS parallel robot is defined as a leg whose length is determined by the lengths of a subset of the actual legs of the robot. This necessarily implies that this subset of legs defines a rigid subassembly. ...
  • Application of distance geometry to tracing coupler curves of pin-jointed linkages 

    Thomas, Federico; Rojas Libreros, Nicolás Enrique (ASME PRESS, 2013)
    Article
    Accés restringit per política de l'editorial
    In general, high-order coupler curves of single-degree-of-freedom plane linkages cannot be properly traced by standard predictor–corrector algorithms due to drifting problems and the presence of singularities. Instead of ...
  • Approaching dual quaternions from matrix algebra 

    Thomas, Federico (2014)
    Article
    Accés obert
    Dual quaternions give a neat and succinct way to encapsulate both translations and rotations into a unified representation that can easily be concatenated and interpolated. Unfortunately, the combination of quaternions and ...