Enviaments recents

  • Visually-guided robot navigation: from artificial to natural landmarks 

    Celaya Llover, Enric; Albarral Garcia, Jose Luis; Jimenez Schlegl, Pablo; Torras, Carme (2007)
    Text en actes de congrés
    Accés obert
    Landmark-based navigation in unknown unstructured environments is far from solved. The bottleneck nowadays seems to be the fast detection of reliable visual references in the image stream as the robot moves. In our research, ...
  • Natural landmark detection for visually-guided robot navigation 

    Celaya Llover, Enric; Albarral Garcia, Jose Luis; Jimenez Schlegl, Pablo; Torras, Carme (2007)
    Text en actes de congrés
    Accés obert
    The main difficulty to attain fully autonomous robot navigation outdoors is the fast detection of reliable visual references, and their subsequent characterization as landmarks for immediate and unambiguous recognition. ...
  • Exploiting single-cycle symmetries in branch-and-prune algorithms 

    Ruiz de Angulo García, Vicente; Torras, Carme (2007)
    Text en actes de congrés
    Accés obert
    As a first attempt to exploit symmetries in continuous constraint problems, we focus on permutations of the variables consisting of one single cycle. We propose a procedure that takes advantage of these symmetries by ...
  • Singularity-free computation of quaternions from rotation matrices in E4 and E3 

    Sarabandi, Soheil; Pérez Gracia, Alba; Thomas, Federico (2018)
    Text en actes de congrés
    Accés obert
    A real orthogonal matrix representing a rotation in E4 can be decomposed into the commutative product of a left-isoclinic and a right-isoclinic rotation matrix. The double quaternion representation of rotations in E4 follows ...
  • A fast branch-and-prune algorithm for the position analysis of spherical mechanisms 

    Shabani, Arya; Sarabandi, Soheil; Porta Pleite, Josep Maria; Thomas, Federico (Springer, 2019)
    Text en actes de congrés
    Accés obert
    Different branch-and-prune schemes can be found in the literature for numerically solving the position analysis of spherical mechanisms. For the prune operation, they all rely on the propagation of motion intervals. They ...
  • Forward kinematics of the general triple-arm robot using a distance-based formulation 

    Rojas, Nicolas; Thomas, Federico (Springer, 2017)
    Text en actes de congrés
    Accés obert
    Distance-based formulations have successfully been used to obtain closure polynomialsfor planar mechanisms without relying, in most cases, on variable eliminations. The methods re-sulting from previous attempts to generalize ...
  • A new insight into the coupler curves of the RCCC four-bar linkage 

    Thomas, Federico; Pérez Gracia, Alba (Springer, 2017)
    Text en actes de congrés
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    Based on the condition for four points to lie on the unit sphere, derived using Distance Geometry, a new mathematical formulation for the coupler curves of the RCCC linkage is presented. The relevance of this formulation ...
  • A singularity-robust LQR controller for parallel robots 

    Bordalba Llaberia, Ricard; Porta Pleite, Josep Maria; Ros Giralt, Lluís (Institute of Electrical and Electronics Engineers (IEEE), 2018)
    Text en actes de congrés
    Accés obert
    Parallel robots exhibit the so-called forward singularities, which complicate substantially the planning and control of their motions. Often, such complications are circumvented by restricting the motions to singularity-free ...
  • The forward kinematics of doubly-planar Gough-Stewart platforms and the position analysis of strips of tetrahedra 

    Porta Pleite, Josep Maria; Thomas, Federico (Springer, 2018)
    Text en actes de congrés
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    A strip of tetrahedra is a tetrahedron-tetrahedron truss where any tetrahedron has two neighbors except those in the extremes which have only one. The problem of finding all the possible lengths for an edge in the strip ...
  • Grasping unknown objects in clutter by superquadric representation 

    Makhal, Abhijit; Thomas, Federico; Pérez Gracia, Alba (Institute of Electrical and Electronics Engineers (IEEE), 2018)
    Text en actes de congrés
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    In this paper, a quick and efficient method is presented for grasping unknown objects in clutter. The grasping method relies on real-time superquadric (SQ) representation of partial view objects and incomplete object ...
  • Yet another approach to the Gough-Stewart platform forward kinematics 

    Porta Pleite, Josep Maria; Thomas, Federico (2018)
    Text en actes de congrés
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    The forward kinematics of the Gough-Stewart platform, and their simplified versions in which some leg endpoints coalesce, has been typically solved using variable elimination methods. In this paper, we cast doubts on whether ...
  • Randomized planning of dynamic motions avoiding forward singularities 

    Bordalba Llaberia, Ricard; Ros Giralt, Lluís; Porta Pleite, Josep Maria (Springer International Publishing, 2018)
    Text en actes de congrés
    Accés obert
    Forward singularities, also known as direct, or actuator singularities, cause many problems to the planning and control of robot motions. They yield position errors and rigidity losses of the robot, and generate unbounded ...

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