Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Function Synthesis of 2-Loop And/Or 2-Dof Mechanisms
(01. Izmir Institute of Technology, 2023) Bağdadioğlu, Barış; Kiper, Gökhan
Kinematic synthesis problems are important in mechanism and machine science. This thesis focuses on function synthesis. The synthesis of different mechanisms with 1 and 2 degrees-of-freedom (dof) are issued by using least squares and Chebyshev approximations. There are various studies with these approaches in the literature. However, there are not many studies of function synthesis of 2-dof mechanisms in the literature. The aim is to study function synthesis of 2-loop and 2 dof mechanisms. 2-dof planar 5R mechanism, 1-dof Bennet 6R mechanisms, 2-dof 7R double-spherical mechanism and finally 7R planar 2-dof mechanism are worked out for function synthesis. It is shown that the function synthesis problems can be solved analytically and semi analytically. The formulations are applied using MS Excel and the results were verified using Solidworks software. It is seen that the numerical results give reliable results and construction parameters are successfully determined.
Design, Production and Tests of an Inherently Balanced Mechanism To Be Used as an Endoscope Holder for Endonasal Skull Base Surgery
(01. Izmir Institute of Technology, 2023) Yılmaz, Tuğrul; Van der Wijk, Volkert; Kiper, Gökhan
Robotic surgery is popular in minimally invasive operations. Given the requirement for the manipulator to operate around the body-entrance point, it must have a remote center of motion. The main aim of the thesis is to design and prototype a surgical robotic arm with 3 degrees of freedom (2 rotation + 1 translation motion pattern) and a remote center of motion to be used as an endoscope holder in minimally invasive surgery. First, a literature review is conducted on robotic surgery, robots used in minimally invasive surgery and mechanisms with remote center of motion. Then, possible kinematic structures are examined and the most suitable one was selected considering the requirements such as balancing compatibility and workspace. While circular tracking arc mechanism is known in the literature, manipulator based on the modified circular tracking arc is novel. Also, gravity compensation of the circular tracking arc is performed. After the gravity-compensation solution for the manipulator is developed and parametrized by considering the workspace, link lengths and geometries were determined and a solid model was developed for detailed construction. Finally, a prototype of the mechanism is manufactured.
Development of Kinetostatic Design Methodology for Airplane Flap Mechanisms
(01. Izmir Institute of Technology, 2022) Arslan, Gökhan; Kiper, Gökhan; Kiper, Gökhan
The problem focused on this thesis is to minimize the fairing drag of dropped-hinge trailing edge flap mechanism of an aircraft. The background knowledge and literature review about the trailing edge flaps and mechanisms are presented, and two patents are examined. Accordingly, a parametric model for a double circular slotted arc track mechanism with a screw jack drive for a trailing edge flap is presented. This model is used in the kinetostatic design methodology. The methodology is applied for a small aircraft as a case study. The main novelty of this thesis is these model and methodology. According to the results, motor torque requirement for the screw jack is determined. The fairing depth is considerably reduced compared to a dropped hinge type mechanism.
Design of Hidam: Highly Deployable Articulated Mast for Positioning of Satellite Components
(01. Izmir Institute of Technology, 2022) Cebeci, Yunus; Kiper, Gökhan; Kiper, Gökhan
With the emerging space activities, use of deployable structures for aerospace applications increased in recent years. Deployable masts are special types of these structures where longitudinal deployment is required and deployable truss mast is one of the deployable mast types. In this thesis, a new design methodology for deployable truss masts is introduced resulting in superior packing ratio. It is a type of a Wren platform which has a single degree of freedom, and it is called HiDAM: Highly Deployable Articulated Mast. The mathematical model for HiDAM is constructed and the packing ratio is maximized by optimizing part lengths. Considering the set design requirements, the constructional design is carried out, first in two dimensions where mathematical model is developed, then in three dimensions. Along with the constructional design, the prototype of HiDAM is manufactured and assembled for a single deployable unit with which overall mechanism movement can be seen. It is presented that with the proposed deployable truss mast HiDAM, the packing ratio can be increased by about 12% compared to the most recent deployable truss mast examples in the literature.
Function Generation Synthesis of Planar Mechanisms as a Mixed Problem of Correlation of Crank Angles and Dead-Center Design
(Izmir Institute of Technology, 2022) Kadak, Tarık; Kiper, Gökhan
Kinematic synthesis of mechanisms is generally divided into three groups. One of them is function synthesis. In function synthesis, the design of correlation of crank angles and dead dead-center position stand out. These problems have been clearly defined and solved separately. But in some cases, problems may be encountered that require both correlation of crank angles and dead dead-center design. Such problems are called mixed function generation problems. In this thesis, an overview of these mixed function generation problems has been given and many problems have been solved analytically or semi-analytically. 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 have been addressed. A problem including 3 positions and a problem including 4 positions for a slider-crank mechanism have been addressed. All solutions have been reduced to univariate equation and a fast solution has been found. Thus, link lengths can be found quickly by changing the problem inputs. Numerical solutions of all problems have been demonstrated using Excel.
Design of Deployable Structures Comprising Altmann Linkages
(01. Izmir Institute of Technology, 2020) Yıldız, Görkem; Kiper, Gökhan
The main objective of this thesis is to investigate possible mobile networks comprising modified Altmann linkages which can be used as deployable structures. Altmann linkage is an overconstrained single-loop linkage with six revolute joints. Within the scope of this thesis, first a modified version of the Altmann linkage is introduced. The modified version of the linkage allows more feasible solutions for constructional design compared to the original linkage. Then, the loop closure equations are written and input/output relationship of the linkage are obtained. Next, possible networks of modified Altman linkages are examined. The networks are obtained either by taking two common links between adjacent loops, or connecting adjacent loops with two new revolute joints without any common links. Also, mobility analysis is performed for each network. Finally, the deployment stages of obtained networks are modelled in a CAD software. Some of the derived networks are already noted in the literature, but several novel networks are introduced in this thesis.
Design and Experimental Evaluation of a Dynamically Balanced Over-Constrained Planar 6r Parallel Manipulator
(Izmir Institute of Technology, 2019) Özkahya, Merve; Kiper, Gökhan; Dede, Mehmet İsmet Can
With the development of the industry, the number of robots used in the production line is increasing day by day. Particularly, it is known that parallel robots are better in terms of positioning accuracy compared to serial robots based on the stretching of robot arms. In parallel mechanisms, there are many factors such as calibration, stability and dynamic balancing of the mechanism affecting positioning accuracy. The aim of this thesis is to dynamically balancing parallel mechanisms to improve positioning accuracy. In high acceleration applications, the shaking force and moment are the factors that cause vibration in the base of the mechanism. These vibrations can be reduced by designing dynamically balanced mechanisms. In this thesis, over- and simply constrained 6R mechanisms are designed for dynamic balancing studies and prototypes are produced. The counter mass method was used to balance the mechanism dynamically. The design of the masses was made according to the mass information received from the model designed in the computer aided drawing program and the parts of the mechanisms were updated according to their actual mass values after they were produced. The design of the masses is designed according to the mass information from CAD model and the parts of the mechanisms are updated according to their actual mass values after they are produced. Dimensional measurements were taken by FARO Prime Arm device due to faults that may arise from the production in the parts of the mechanism after production. Then the mechanism was assembled. Before carrying out the balancing tests, calibration studies affecting the positioning accuracy of the over-constrained mechanism were carried out. Finally, the mechanism is activated balanced and unbalanced and the acceleration effect of the 6-axis accelerometer is obtained experimentally.
Design of a 2r1t Mechanism With Remote Center of Motion for Minimally Invasive Transnasal Surgery Applications
(Izmir Institute of Technology, 2018) Yaşır, Abdullah; Kiper, Gökhan; Dede, Mehmet İsmet Can
In minimally invasive surgery, use of robotic manipulators is becoming more and more common in order to have more precise operations and better post-operative processes. Such operations are often performed through an incision port (a pivot point) on the patient’s body. Since the manipulator should move about the pivot point, it should have a remote center of motion. In this regard, the main objective of this thesis is designing a 3-dof (degrees-offreedom) surgical robotic arm that is capable of 2R1T (R: rotation, T: translation) motion pattern and is structured as a remote center of motion mechanism for minimally invasive surgery applications. First, the structural synthesis of a 3-dof manipulator with 2R1T motion pattern is performed. The synthesized structures also can be used for any kind of 2R1T-type applications. Then, the manipulators with various kinematic structures are evaluated for a transnasal surgery according to several evaluation criteria such as feasibility of construction for a remote center of motion mechanism, ease of balancing, number of links, structural symmetry, decoupling of the joint inputs and the output motion of the platform and the number of actuators connected to the base. The best option is evaluated as a parallel manipulator with two 1 F0-system and one 1 F0-1 F∞-system leg structures. Afterwards, kinematic analysis of the spatial parallel manipulator is formulated with a simplified kinematic model consisting of three intersecting planes so that dimensional design is done for a desired dexterous workspace. Finally, constructional design is completed and a prototype is manufactured and tested.
Kinematic Design of Scissor Linkages
(Izmir Institute of Technology, 2018) Karagöz, Cevahir; Kiper, Gökhan
The primary objective of this thesis is to propose a design method for linkages simulating the transformation of a planar curve from an initial form to a final form. First, the topologies of fundamental loops are examined using symmetry patterns. Design methodologies for the hence obtained mechanisms are formulated. The given curves are discretized initially, and the nodes are constructed. Then the side lengths of the loops are obtained in order to obtain the desired transformation between the given curves. Finally, different deployable and transformable linkage examples are presented.
Optimal Design of a Kinesthetic Haptic Device Mechanism for Enhancing Its Impedance Characteristics
(Izmir Institute of Technology, 2018) Görgülü, İbrahimcan; Dede, Mehmet İsmet Can; Kiper, Gökhan
In this work, the optimal design of modified version of 3 degrees of freedom RCUBE mechanism has been studied in order to develop a high-performance haptic device mechanism. A high-performance haptic mechanism is achieved by having high transparency and high-frequency range. These two properties are determined by the mechanical impedance of the mechanism. Hence, to increase the quality of a haptic mechanism, its mechanical impedance performance must be enhanced. This refers to have low inertia, low friction, high back-drivability, high force output, high structural stiffness, and high manipulability for the mechanism. All these properties are designated by kinematic, stiffness, and dynamic properties of the mechanism. Hence, as a first step of this thesis, kinematic, stiffness and dynamic models of the mechanism are analytically procured. The analytical model of stiffness is achieved via the virtual joint method. Then, in order to obtain the objective function for the design procedure, performance metrics affecting the above-mentioned properties are reviewed and produced. Since these metrics have common parameters such as link lengths and the cross-section area of the links, there is a highly non-linear and contradictory relationship between the metrics. In order to deal with the non-linearity and to determine the global optimum design, an evolutionary optimization method, genetic algorithm, is preferred. The optimization time is reduced by investigating the most critical poses of the workspace and reducing the performance metrics to simpler forms. The link lengths and the cross-section areas are optimized. Carbon fiber tubes are used as links. The Pareto-front solution set is obtained as a result of the optimization procedure.Finally, an optimal solution is proposed and evaluated for the design of this modified R-CUBE mechanism to be used in haptic applications.

Master Degree / Yüksek Lisans Tezleri

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