Master Degree / Yüksek Lisans Tezleri

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

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Access Right: Open AccessSubject: search.filters.subject.Parallel manipulators

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Now showing 1 - 5 of 5
  • Master Thesis
    Gravity Compensation of a 2r1t Mechanism With Remote Center of Motion for Minimally Invasive Transnasal Surgery Applications [master Thesis]
    (01. Izmir Institute of Technology, 2021) Aldanmaz, Ataol Behram; Artem, Hatice Seçil; Dede, Mehmet İsmet Can; Artem, Hatice Seçil; Dede, Mehmet İsmet Can
    In this work, gravity balancing of a 2URRR-URR parallel manipulator is issued. The manipulator is designed as an endoscope holder for minimally invasive transnasal pituitary gland surgery application. In the surgery, the endoscope is placed through the nostril of the patient where there is a natural path to the pituitary gland. In case of a motor failure, in order to protect the patient and to ease the control of the manipulator static balancing for this manipulator is worked out, the manipulator prototype is balanced and tested. The parallel manipulator has three legs. The payload mass has been distributed to side legs due to workspace limitations. By using counter-mass for two links in each leg, the center of mass of each leg has been reduced to the proximal link which simplified the balancing problem to balancing of a two degree-of-freedom inverted pendulum. By connecting a zero free length spring to the proximal link the total mass of the leg the manipulator has been kept in static balance in its desired workspace. Simulations show that with the applied design, torque effects on the motors have been reduced by 93.5%. Finally, the balancing solution is applied on the manipulator with active motors and the manipulator has been balanced, the torque values mostly has been decreased where the joint clearance, spring tension adjustments and mechanical constraints has affected the results. With the elimination of the joint clearance, mechanical constraints and rearranging the spring tension the required torque could be minimized.
  • Master 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.
  • Master Thesis
    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.
  • Master Thesis
    Type Synthesis and Instantaneous Mobilty Analysis of 3-Upu Parallel Manipulators
    (Izmir Institute of Technology, 2017) Boztaş, Sercan; Kiper, Gökhan
    In this study, the literature was examined and known derivatives of the 3-UPU parallel manipulator were investigated to reveal the mobility characteristics of the 3-UPU parallel manipulator. For a 3-UPU parallel manipulator, U represents the universal joint, while P represents the prismatic joint. It is a very well-known manipulator that can provide the platform with three degrees of freedom of pure translation, pure rotation or mixed translation and rotation with respect to the base, according to the relative directions of revolute joint axes. For this reason, in this study, alternative joint axis orientations on the platforms and the limbs are examined. The generated joint layouts for the platforms were matched with each other to generate and classify alternative manipulator architectures based on some assumptions. The topological structures of thus obtained parallel manipulators are examined and limb types were determined. These limb types were then analyzed with the help of screw theory. Reciprocal screw sets were analyzed by singular value decomposition method and the instantaneous degrees of freedom of the manipulators and the motion characteristics of the moving platforms are tabulated. The finite mobility analysis of one the parallel manipulators is performed using Solidworks Motion as an example. Among several different 3-UPU parallel manipulator architectures, especially 118 novel 3-UPU parallel manipulators with non-parasitic three degrees-of-freedom are significantly important. The classified 3-UPU parallel manipulators with determined motion characteristics can be used by researchers as a design alternative for a specific design task.
  • Master Thesis
    Modelling and Control of a 3-Rrs Parallel Manipulator
    (Izmir Institute of Technology, 2016) Tetik, Halil; Kiper, Gökhan
    The focus of this thesis study is to model and control a parallel robot manipulator located in Rasim Alizade Mechatronics Laboratory (Izmir Institute of Technology Mechanical Engineering Department). The purpose of this robot is to manipulate heavy payloads. It is considered as the base part of a hybrid manipulator. This thesis study deals with a 3-RRS parallel manipulator with 3 identical limbs. Each limb comprises two parallel revolute joint axes. The manipulator has a base and a moving platform which are in the shape of equilateral triangles. The mobile platform of this manipulator has 3-degrees-of-freedom: it can rotate around x- and y-axes and translate along the z-axis. To obtain the mathematical model of the parallel manipulator, firstly the mobility analysis is performed. Then, a constraint analysis is performed to obtain the dependent pose parameters of the moving platform in terms of the independent parameters. Following that kinematic, singularity, workspace and inverse dynamic analyses are performed. To validate the mathematical model of the PM, several simulations are run in MATLAB/Simulink R environment. Once the mathematical model is validated, the control studies are carried out. The motion of the 3-RRS PM is controlled by activating stepper motors with two different controllers (a CNC controller and a PCI card). To obtain a desired motion of the moving platform, firstly the desired task space coordinates of the moving platform are transformed into joint space coordinates using inverse kinematics. With the CNC controller a trapezoidal velocity, with the PCI card a trapezoidal jerk profile is generated. To test the control over the PM, 3 magnetic encoders are attached to the shafts of input links at each limb. Furthermore, a 3-axis gyroscope is attached to the center of the moving platform to track its rotational trajectory.