Examinando por Autor "Achiche, S."

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    Ítem
    Force-Displacement Model of Compliant Mechanisms using Assur Sub-Chains
    (2011-06) Durango, S.; Correa, J.; Ruíz, O.; Aristizábal, M.; Restrepo-Giraldo, J.; Achiche, S.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
    This article develops a modular procedure to perform force-displacement modeling of planar flexurebased compliant mechanisms (CMs) -- The procedure is mostly suitable for planar lumped CMs -- To achieve the position analysis of CMs requires: (i) to implement the kinematic analysis as for ordinary mechanisms, (ii) to solve equilibrium problem by means of an static analysis and (iii) to model the flexures behavior through a deflection analysis -- The novel contribution of this article relies on the fact that a division strategy of the CM into Assur subchainsm is implemented, so that any CM subjected to such disaggregation can be accurately modeled -- For this purpose a mathematical model for leaf-spring flexure type is presented and used through this paper -- However any other flexure model can be used instead -- To support the technique, a three Degrees–Of–Freedom (3-DOF) flexure-based parallel mechanism is used as case study -- Results are compared to a Finite Element Analysis (FEA)
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    Ítem
    Symmetrical Observability of Kinematic Parameters in Symmetrical Parallel Mechanisms
    (Editora Edgard Blücher Ltda., 2014-05) Durango, S.; Restrepo, D.; Ruíz, O.; Restrepo-Giraldo, J.; Achiche, S.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
    This article presents an application of symmetry group theory in kinematic identification of parallel mechanisms of nlegs legs -- Kinematic Identification implies the estimation of the actual geometrical parameters (as opposed to nominal ones) of a physical mechanism -- For a symmetric mechanism, KI requires configuring sets of leg positions with symmetrical observability – This article presents as main contributions: (i) a conjecture that allows mapping the symmetries of the mechanism into the active-joint workspace, (ii) a set of necessary conditions to express leg parameters in coordinate systems which allow symmetrical observability, and (iii) a procedure for exploiting symmetries in pose selection for kinematic identification of symmetrical parallel mechanisms -- For the kinematic identification itself, we adopt a divide-and-conquer (DC) identification protocol -discussed by us in another publication- in which each leg of the mechanism is independently identified by using the inverse calibration method -- In this article we emphasize how to exploit the symmetries existent in (nlegs − 1) legs of the parallel mechanism allowing to apply to other legs the symmetry-transformed sample protocol used for the kinematic identification of a reference leg -- The symmetrical observability of sets of leg parameters allows to reduce the costs of the pose selection procedure by a factor of (1/nlegs) compared to a complete DC procedure in which the poses of each leg are selected independently -- The pose selection is carried out only for the reference leg -- For the (nlegs−1) remaining legs the poses are dictated by symmetry operations performed onto the poses of the reference leg -- An application of the symmetrical observability is presented through the simulated kinematic identification of a 3RRR symmetrical parallel mechanism