Browsing by Author "Thomas, Federico"

A bilinear formulation for the motion planning of nonholonomic parallel orienting platforms
Grosch Obregon, Patrick John; Thomas, Federico (Institute of Electrical and Electronics Engineers (IEEE), 2013)
Conference report
Open AccessThis paper deals with the motion planning problem for parallel orienting platforms with one nonholonomic joint and two prismatic actuators which can maneuver to reach any threedegreeoffreedom pose of the moving platform. ... 
Accurate computation of quaternions from rotation matrices
Sarabandi, Soheil; Thomas, Federico (Springer International Publishing, 2018)
Conference report
Open AccessThe main nonsingular alternative to 3×3 proper orthogonal matrices, for representing rotations in R3, is quaternions. Thus, it is important to have reliable methods to pass from one representation to the other. While ... 
A coordinatefree approach to tracing the coupler curves of pinjointed linkages
Rojas Libreros, Nicolás Enrique; Thomas, Federico (ASME PRESS, 2011)
Conference report
Restricted access  publisher's policyIn general, highorder coupler curves of plane mechanisms cannot be properly traced by standard predictorcorrector algorithms due to drifting problems and the presence of singularities. Instead of focusing on finding ... 
A distancebased formulation of the octahedral manipulator kinematics
Rojas Libreros, Nicolás Enrique; Borràs Sol, Júlia; Thomas, Federico (2010)
Conference report
Open AccessIn most practical implementations of the GoughStewart platform, the octahedral form is either taken as it stands or is approximated. The kinematics of this particular instance of the GoughStewart platform, commonly known ... 
A distance geometry approach to the singularity analysis of 3R robots
Thomas, Federico (ASME PRESS, 2015)
Article
Restricted access  publisher's policyThis 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 family of quadraticallysolvable 5SPU parallel robots
Borràs Sol, Júlia; Thomas, Federico; Torras, Carme (2010)
Conference report
Open AccessA 5SPU 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 multiloop linkages
Porta Pleite, Josep Maria; Ros Giralt, Lluís; Thomas, Federico (2008)
External research report
Open AccessThis report presents a new method able to isolate all configurations that a multiloop 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
Open AccessThis 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 matrixbased approach to the image moment problem
Martínez Bauzà, Judit; Porta Pleite, Josep Maria; Thomas, Federico (200611)
Article
Open AccessAn 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 ... 
Analysing the singularities of 6SPS parallel robots using virtual legs
Borràs Sol, Júlia; Thomas, Federico; Torras, Carme (LIRMM, 2008)
Conference report
Open AccessA virtual leg in a 6SPS 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. ... 
A new insight into the coupler curves of the RCCC fourbar linkage
Thomas, Federico; Pérez Gracia, Alba (Springer, 2017)
Conference report
Open AccessBased 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 onemotor fullmobility 6PUS manipulator
Grosch Obregon, Patrick John; Gregorio, Raffaele di; Thomas, Federico (Springer, 2010)
Conference report
Open AccessThis paper presents the feasibility study of an underactuated parallel manipulator with 6PUS topology, destined to handle worktables in CNC machine tools. The proposed device exploits the fact that, in such an application, ... 
Application of distance geometry to tracing coupler curves of pinjointed linkages
Thomas, Federico; Rojas Libreros, Nicolás Enrique (ASME PRESS, 2013)
Article
Restricted access  publisher's policyIn general, highorder coupler curves of singledegreeoffreedom 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
Open AccessDual 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 ... 
Architectural singularities of a class of pentapods
Borràs Sol, Júlia; Thomas, Federico; Torras, Carme (2011)
Article
Open AccessA pentapod is usually defined as a 5degreesoffreedom fullyparallel manipulator with an axial spindle as moving platform. This kind of manipulators has revealed as an interesting alternative to serial robots handling ... 
Architecture singularities in flagged parallel manipulators
Borràs Sol, Júlia; Thomas, Federico; Torras, Carme (IEEE, 2008)
Conference report
Open AccessFlagged manipulators are of interest because they are the only StewartGough platforms for which a cell decomposition of their singularity loci is available. Here we show that the known family of such manipulators can be ... 
A reconfigurable 5DoF 5SPU parallel platform
Borràs Sol, Júlia; Thomas, Federico; Ottaviano, Erika; Ceccarelli, Marco (2009)
Conference report
Open AccessThis paper presents a 5SPU 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 reconfigurable asymmetric 3UPU parallel robot
Sarabandi, Soheil; Grosch Obregon, Patrick John; Porta Pleite, Josep Maria; Thomas, Federico (2018)
Conference report
Open AccessParallel robots with three UPU legs have received a lot of attention due to the possibility of assembling these legs so that the robot performs either a pure translational or a pure rotational motion. Nevertheless, some ... 
A robust forward kinematics analysis of 3RPR planar platforms
Rojas Libreros, Nicolás Enrique; Thomas, Federico (Springer Verlag, 2010)
Conference report
Open AccessThe standard forward kinematics analysis of 3RPR 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
Restricted access  publisher's policyAt 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 ...