Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Enhancement of Trajectory Following Accuracy of High Acceleration Robots by Using Their Stiffness Properties(01. Izmir Institute of Technology, 2021) Paksoy, Erkan; Dede, Mehmet İsmet Can; Paksoy, Erkan; Dede, Mehmet İsmet CanIn recent years, there has been a push for the incorporation of robots into manufacturing processes. In general, parallel robots are preferred for processes requiring high repeatability and positioning accuracy. If the positioning accuracy of the end-effector of a robot has high priority, compliance characteristics of the elements of its mechanism should be considered. Due to the high accelerations or external loading on the robot, the dimensions of the elements change and this leads to positioning errors for the end-effector. This thesis describes an experimental test setup and an experimental procedure for determining the compliance characteristics of planar mechanisms, followed by a comparison of the repeatability and stiffness performance of a parallel and an over-constrained mechanism. Finally, assumptions and methodology for using this compliance information to improve the trajectory tracking accuracy of high-accelerated robots are given. Portable coordinate measurement machine and calibrated weights are used to collect compliance information. The compliance behavior of the mechanisms defined for entire workspace by using the least squares and bilinear interpolation techniques. The D'Alambert principle is used to estimate fictitious forces that cause the compliance of the mechanism's end-effector while the mechanism operates at up to 5 g accelerations. As a result of this thesis, it is demonstrated that the mechanism's center of gravity and joint types play an important role in the mechanism's trajectory tracking accuracy, and that tracking accuracy can be improved by a simple data-driven compliance prediction algorithm.Master Thesis Development and Experimental Verification of the Stiffness Matrix of the Hiphad Haptic Device(Izmir Institute of Technology, 2015) Taner, Barış; Dede, Mehmet İsmet CanIn this work the evaluation of stiffness performance of HIPHAD haptic device has been studied with 2 semi-analytical and an experimental method in order to obtain the stiffness characteristics of the haptic device for precise motion tracking performance. Since the compliance of a robot depends highly on robot configuration and force is variable in the haptic applications, stiffness properties of main robot elements and methods of evaluating stiffness of a robot manipulator is investigated considering the computational costs. Virtual Joint Method (VJM) and Structural Matrix Analysis (SMA) method is applied to the case study. Although, structural matrix analysis reduces the computational time dramatically by reducing the node elements it is not accurate as Finite Element Analysis (FEA) method. Comparing the VJM to the SMA, it is applicable to online application due to its simplicity and flexibility. In addition, with FEA based link modelling VJM is as accurate as FEA method in finding stiffness of the manipulator. While both methods can include flexible joints FEA based link stiffness parameters computational costs for these methods is the performance criteria for choosing one. For the case study HIPHAD, the VJM method provides better result in terms of flexibility and computation cost with 0.035 seconds finding the resultant force while SMA method calculates result in 0.074 seconds.