Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
Search Results
Master Thesis Optimum Design and Analysis of Torsion Spring Used in Series Elastic Actuators for Rehabilitation Robots(01. Izmir Institute of Technology, 2021) Erten, Hacer İrem; Artem, Hatice SeçilAlong with the developing technology, robotic systems have started to take place in areas where there is one-to-one interaction with people, as well as their use in industrial areas. As the robotic system began to take place in daily life, safety and reliability between humans and robots have become a critical issue. In this context, a series elastic actuator has been developed for the aforementioned robotic systems, which has an elastic element placed in series between the motor output and the mechanical output. In this thesis, the torsion spring, as a critical part for the rotary series elastic actuators of rehabilitation robots, which helps support the extension and flexion of the knee joint during physical therapy of individuals with lower extremity disorders, is discussed. First of all, the data required for modeling was produced by making analyses with the design of experiment and finite element method. In line with the design goal of a light, compact, durable and stiff spring, the torsion spring whose topology was determined was modelled using a hybrid method: Neuro-regression approach and cross-validation technique. To minimize the mass and von Mises stress of the torsion spring, the thickness of the spring and the inner corner radius of the flexible leg are taken as the design variables and multi-objective optimization problems are created. The design and optimization of the torsion spring was done with the help of Differential Evolution, Nelder-Mead, Random Search and Simulated Annealing algorithms. By comparing the obtained optimization results with the finite element method and the results in the literature, it has been seen that the model and optimization methods used in the study are reliable and applicable.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.