Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Citation - WoS: 10Citation - Scopus: 10Stiffness Modeling of a 2-Dof Over-Constrained Planar Parallel Mechanism(Elsevier, 2023) Görgülü, İbrahimcan; Dede, Mehmet İsmet Can; Kiper, GökhanStiffness model acquisition of over-constrained parallel mechanisms is relatively difficult since they have more than necessary kinematic loops. In this study, a stiffness modeling solution for over-constrained parallel mechanisms is proposed while considering the computational cost efficiency. Three contributions of the paper are: (1) Presenting the stiffness modeling procedure for serially connected closed-loop structures by using the Virtual Joint Method (2) Considering the effect of dynamic auxiliary forces and dynamic external forces on the mobile platform's deflection and achieving a direct solution by using superposition principle (3) A model fitting procedure for modifying the stiffness coefficients to comply with the experimental data. A 2 degrees-of-freedom over-constrained parallel mechanism is investigated as a case study. However, the proposed stiffness model is 6-DoF since compliant deflections occur in any direction. A finite element analysis and an experimental study verify the model's results.Article Citation - WoS: 24Citation - Scopus: 30Time Efficient Stiffness Model Computation for a Parallel Haptic Mechanism Via the Virtual Joint Method(Elsevier, 2020) Carbone, Giuseppe; Görgülü, İbrahimcan; Dede, Mehmet İsmet CanHaptic devices are used for displaying a range of mechanical impedance values to the user. This impedance is regulated by a real-time control loop depending on the position information of the end-effector, which is usually acquired indirectly by using forward kinematics equations. Nevertheless, the kinematic model is insufficient to obtain accurate values if there are non-negligible compliant displacements. This gives a strong motivation for implementing a real-time stiffness model in the haptic control loop for improving its accuracy. Additionally, stiffness performance indices can be used at the design stage for enhancing the haptic devices impedance range within optimal design procedures. Fast solutions of a stiffness model are required for a real-time control as well as for decreasing the optimization time during a design process with a trade-off between accuracy and computational costs. In this study, we propose a computation time-efficient stiffness analysis of a parallel haptic device mechanism. The accuracy and computational costs of the proposed model are calculated and compared with a model that is obtained via a finite element method to demonstrate the effectiveness of the proposed approach with the desired real-time and accuracy performance. (C) 2019 Elsevier Ltd. All rights reserved.