Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Department: search.filters.department.İzmir Institute of TechnologyPublisher: search.filters.publisher.Ieee-inst Electrical Electronics Engineers inc

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  • Editorial
    Comments on “Relaxed Conditions for the Input-to-State Stability of Switched Nonlinear Time-Varying Systems”
    (Ieee-inst Electrical Electronics Engineers inc, 2025) Şahan, Gökhan; Trenn, Stephan; 04.02. Department of Mathematics; 04. Faculty of Science; 01. Izmir Institute of Technology
    This study addresses the deficiencies in the assumptions of the results in (Chen and Yang, 2017) due to the lack of uniformity. We first show the missing hypothesis by presenting a counterexample. Then, we prove why they are wrong in that form and show the errors in the proof of the main result of (Chen and Yang, 2017). Next, we compare the assumptions and related results of (Chen and Yang, 2017) with similar works in the literature. Lastly, we give suggestions to complement the shortcomings of the hypotheses and thus correct them.
  • Article
    A Framework for Adaptive Load Redistribution in Human-Exoskeleton Systems
    (Ieee-inst Electrical Electronics Engineers inc, 2025) Mobedi, Emir; Solak, Gokhan; Ajoudani, Arash; 01. Izmir Institute of Technology
    Wearable devices like exoskeletons are designed to reduce excessive loads on specific joints of the body. Specifically, single- or two-degrees-of-freedom (DOF) upper-body industrial exoskeletons typically focus on compensating for the strain on the elbow and shoulder joints. However, during daily activities, there is no assurance that external loads are correctly aligned with the supported joints. Optimizing work processes to ensure that external loads are primarily (to the extent that they can be compensated by the exoskeleton) directed onto the supported joints can significantly enhance the overall usability of these devices and the ergonomics of their users. Collaborative robots (cobots) can play a role in this optimization, complementing the collaborative aspects of human work. In this study, we propose an adaptive and coordinated control system for the human-cobot-exoskeleton interaction. This system adjusts the task coordinates to maximize the utilization of the supported joints. When the torque limits of the exoskeleton are exceeded, the framework continuously adapts the task frame, redistributing excessive loads to non-supported body joints to prevent overloading the supported ones. We validated our approach in an equivalent industrial painting task involving a single-DOF elbow exoskeleton, a cobot, and four subjects, each tested in four different initial arm configurations with five distinct optimisation weight matrices and two different payloads.
  • Article
    Finite-Dimensional Backstepping Controller Design
    (Ieee-inst Electrical Electronics Engineers inc, 2025) Özsarı, Türker; Ozsari, Turker; Yilmaz, Kemal Cem; 04.02. Department of Mathematics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this article, we introduce a finite-dimensional version of backstepping controller design for stabilizing solutions of partial differential equations (PDEs) from boundary. Our controller uses only a finite number of Fourier modes of the state of solution, as opposed to the classical backstepping controller which uses all (infinitely many) modes. We apply our method to the reaction-diffusion equation, which serves only as a canonical example but the method is applicable also to other PDEs whose solutions can be decomposed into a slow finite-dimensional part and a fast tail, where the former dominates the evolution in large time. One of the main goals is to estimate the sufficient number of modes needed to stabilize the plant at a prescribed rate. In addition, we find the minimal number of modes that guarantee the stabilization at a certain (unprescribed) decay rate. Theoretical findings are supported with numerical solutions.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Torque-Current Relationship of an Mr Brake for Its Open-Loop Control
    (Ieee-inst Electrical Electronics Engineers inc, 2024) Dede, Mehmet İsmet Can; Bozelli, Muhammed Rza; Dede, Mehmet Ismet Can; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Active and semiactive actuators have been widely preferred for designing an actuation system for kinesthetic-type haptic devices. Among them, magnetorheological fluid-based brakes (MR brakes) offer potent properties, such as high torque/inertia ratio and less power consumption. However, one of the most critical issues to be resolved is their hysteresis behavior. Various methods for modeling the input/output relationship with hysteresis behavior exist. However, hysteresis compensation approaches, i.e., torque-current hysteresis model, are not widely studied for MR Brakes. Therefore, a hysteresis compensation model approach to account for the nonlinear behavior of MR Brake is proposed, and the model is experimentally validated in this article. The model consists of multiple splines and an algorithm that uses these splines in hysteresis compensation. Being relatively simple and easily implementable are the distinguished features of the presented model since an optimization method is not required. Furthermore, the performance of the proposed method is compared with two methods, torque-to-current mapping and inverse Prandtl-Ishlinskii method. The obtained experimental results are investigated with three performance metrics. Finally, the effect of the operational speed on the performance of the hysteresis compensation model is also discussed.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Multi-Haps Thz Satellite Communication: Error and Capacity Analyses Under I/Q Imbalance
    (Ieee-inst Electrical Electronics Engineers inc, 2024) Erdoğan, Eylem; Altunbas, Ibrahim; Erdogan, Eylem; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Satellite communication (SatCom) has become an important field of research to accomplish the requirements of next-generation wireless communication systems such as high data rates and capacity while providing global coverage. Besides traditional communication applications, SatCom is gathering more and more attention as it enhances the performance of sensing applications, such as environmental monitoring, atmospheric pollution monitoring, and so on. To deliver worldwide service and improve accurate data collection in sensor networks, high-altitude platform station (HAPS) systems can be employed in SatCom. Moreover, utilizing terahertz (THz) frequencies in HAPS-assisted SatCom systems offers incredibly high bandwidths, enabling extreme data rates and higher resolution in sensing applications. In this article, a THz SatCom system model is considered where K number of HAPS systems are deployed to assist the transmission between a low-Earth-orbit satellite and a ground station by utilizing variable-gain amplify-and-forward (AF) relaying. The symbol error rate (SER) and ergodic capacity analyses are performed in the presence of attenuation depending on the atmospheric conditions, fading, pointing error (PE), and in-phase and quadrature (I/Q) imbalance. Theoretical findings are validated through Monte-Carlo simulations.