Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 1Citation - Scopus: 1Reconfigurable Polyhedral Mechanisms Using Scissor-Like Elements with Cantellation Transformation Between Dual Geometries(Pergamon-Elsevier Science Ltd, 2025) Liao, Yuan; Kiper, Gokhan; Krishnan, SudarshanDeployable polyhedron mechanisms (DPMs) have garnered significant interest in architecture, aerospace, and robotics, where reconfigurable and space-efficient structures are crucial. This paper presents a tangential design method for DPMs using scissor-like elements (SLEs). Scissor units are placed along the edges of an equilateral polyhedron, tangential to its midsphere. This method enables the mechanisms to transform between a polyhedron and its dual, following the cantellation operation. Using screw theory, the kinematic properties of these mechanisms are analyzed. Results show that the DPMs exhibit 1-degree of freedom (DOF) under normal conditions and gain additional DOFs at multifurcation points, allowing for reconfigurable motion modes. Physical models based on various geometries, including Platonic, Archimedean, Johnson, and Catalan solids, help to validate the method's feasibility. Observations indicate that this method is only applicable to equilateral supporting polyhedra. The transformability and reconfigurability observed in these mechanisms demonstrate the potential of this approach for applications in architecture, aerospace, and robotics.Article Citation - WoS: 1Citation - Scopus: 1A New Safe Flexible Torsion Joint Design With Softening Stiffness Characteristics(Pergamon-elsevier Science Ltd, 2025) Gorgulu, Ibrahimcan; Dede, Mehmet Ismet Can; Kiper, GokhanThis paper introduces a novel flexible joint design that enhances mechanical versatility. The design shows how to obtain bidirectional deflections from a unidirectional spring. It enables the parallel and serial connections of springs. It features multiple stiffness regions determined by applied load levels, eliminating the need for a clutch mechanism. Mechanical limits can be added to customize stiffness, offering more hardening or softening regions. The design also allows for connecting multiple flexible joint units in series. In a case study, the series flexible joint design is developed with two flexible joint units, providing a softening stiffness characteristic. The joint has rigid, stiff, and soft regions. When used as a series elastic actuator in a robot manipulator, the rigid region aims to conduct the tasks at low torque levels, i.e., trajectory tracking. The stiff region is preserved for collaborative tasks in human-robot interaction, while the soft region enhances the robot's safety in case of control failure or collision. Static and dynamic test results comply with the ideal model. This flexible joint design improves mechanical performance, safety, and adaptability.Article Citation - WoS: 2Citation - Scopus: 2Function Generation With Planar Four-Bar Mechanisms as a Mixed Problem of Correlation of Crank Angles and Dead Center Design(Springer india, 2024) Kadak, Tarik; Kiper, GokhanFunction generation synthesis of mechanisms can be considered as the design of correlation of crank angles and dead dead-center position design. These two problems have been clearly defined and solved separately. But some problems may require both correlation of crank angles and dead dead-center design at different configurations. Such problems are called mixed function generation problems. In this paper, an overview of these mixed function generation problems for the planar four-bar mechanism are given and the problems are solved analytically or semi-analytically. Except three of them, all presented mixed function generation problem formulations are novel. The solutions of all problems including three positions for the four-bar mechanism and the solution of a problem including four positions for a four-bar mechanism are addressed. All problems are first reduced to a univariate equation and a fast solution is found. Thus, link lengths can be found quickly by changing the problem definition problems, and several design iterations can be performed in a short time. Numerical solutions of all problems have been demonstrated using Excel.Article Citation - WoS: 12Citation - Scopus: 13Mobility Analysis of Tripod Scissor Structures Using Screw Theory(Pergamon-elsevier Science Ltd, 2024) Liao, Yuan; Kiper, Gokhan; Krishnan, SudarshanMechanisms consisting of spatial scissor units have different kinematic behaviors than those of planar scissors. However, their kinematics, especially the mobility analysis, has not received enough attention. Two types of deployable asseblies are analyzed in this paper, namely the translational and mirrored assemblies. Both the assemblies are made of tripod scissor units, and their instantaneous mobility are examined using screw theory. The study starts on the configuration where all the members have the identical deployment angle. Firstly, the geometric property of each assembly was studied. Then, screw-loop equations were developed based on graph theory and closure equations. Finally, the mobility of each assembly was computed using linear algebra. Following the analysis, physical prototypes were constructed to validate the results, and several different motion modes were obtained for the translational assembly. The analysis reveals different kinematic behaviors of the two assemblies. In the given configuration, the translational assemblies have four instantaneous degrees of freedom, while the mirrored assemblies have only a single instantaneous degree of freedom.