Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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Author: search.filters.author.Mobedi, Emir

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  • Conference Object
    Velocity-Level Kinematics of a Continuously Variable Transmission System for Phri
    (Springer International Publishing AG, 2025) Mobedi, Emir; Dede, Mehmet Ismet Can
    New generation robots pave the way for physical human-robot interaction (pHRI) through improvements in control and design techniques. While the former is achieved with the help of a number of sensory information, variable stiffness actuators (VSA) are exploited for the design of these robots to achieve inherent compliance. Recently, continuously variable transmission-based VSA has been developed to be used for pHRI, specifically for haptics. The fundamental characteristic of this new CVT mechanism is that it regulates output position and torque independently via the sphere transmission element. In this study, velocity-level kinematics of this new CVT system is carried out to demonstrate its step-less speed variation feature. Moreover, simulations are conducted in ADAMS and Solidworks software packages at 8 transmission points selected unequally. Results show that the average value of overall ADAMS and Solidworks errors computed with respect to the computed velocity are reported as 1.09%, and 0.53%, respectively.
  • Article
    A Framework for Adaptive Load Redistribution in Human-Exoskeleton Systems
    (Ieee-inst Electrical Electronics Engineers inc, 2025) Mobedi, Emir; Solak, Gokhan; Ajoudani, Arash
    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.
  • Conference Object
    Citation - Scopus: 3
    A Continuously Variable Transmission System Designed for Human–robot Interfaces
    (Springer, 2021) Mobedi, Emir; Dede, Mehmet İsmet Can
    Within a predefined limit, continuously variable transmission (CVT) systems can continuously vary the power transmission ratio. The transmission in CVTs is achieved via friction, belt or gear systems. If CVT designs can incorporate backdrivability, independent output position and impedance variation, shock absorbtion, and low mass and inertia, they can be employed in human–robot interfaces. Among various types of CVT designs, the two-cone drive CVT designs have a major drawback since the output torque and position cannot be changed independent of each other. The friction wheel used in this design does not have a holonomic motion capability and causes this inconvenience. In order to overcome this problem, a sphere is used in this work for the CVT design as the transmission element. In addition, it is stated in the literature that common CVT drive systems do not have the capability to be used in cyclic bidirectional motion. In the presented CVT design, a second sphere is added to the system with two springs from the lower part of the cones for pretension in order to solve the bidirectional transmission problem. In this paper, the working principle and conceptual design details of the novel two-cone CVT drive are presented. Experimental results showed that the novel CVT has the capacity to transmit bidirectional power with some accuracy. © 2021, Springer Nature Singapore Pte Ltd.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    A Continuously Variable Transmission-Based Variable Stiffness Actuator for Phri: Design Optimization and Performance Verification
    (American Society of Mechanical Engineers, 2024) Mobedi, Emir; Dede, Mehmet İsmet Can
    Physical human–robot interfaces (pHRIs) enabled the robots to work alongside the human workers complying with the regulations set for physical human–robot interaction systems. A variety of actuation systems named variable stiffness/impedance actuators (VSAs) are configured to be used in these systems’ design. Recently, we introduced a new continuously variable transmission (CVT) mechanism as an alternative solution in configuring VSAs for pHRI. The optimization of this CVT has significant importance to enhance its application area and to detect the limitations of the system. Thus, in this paper, we present a design optimization approach (an adjustment strategy) for this system based on the design goals, desired force, and minimization of the size of the system. To implement such design goals, the static force analysis of the CVT is performed and validated. Furthermore, the fabrication of the optimized prototype is presented, and the experimental verification is performed considering the requirements of VSAs: independent position and stiffness variation, and shock absorbing. Finally, the system is calibrated to display 6 N continuous output force throughout its transmission variation range. © 2024 by ASME.
  • Book Part
    Citation - WoS: 1
    Citation - Scopus: 1
    Calibration Study of a Continuously Variable Transmission System Designed for Phri
    (Springer, 2020) Mobedi, Emir; Dede, Mehmet Ismet Can
    Variable stiffness actuators (VSAs) have been used in many applications of physical human-robot interfaces (pHRI). A commonly employed design is the spring-based VSA allowing the user to regulate the output force mechanically. The main design criteria of these actuation systems are the adjustment of output force independent from the output motion, and shock absorbing. In our recent work, we implemented certain modifications on the two-cone friction drive continuously variable transmission system (CVT) so that the CVT can be employed in pHRI systems. Subsequently, the optimized prototype is developed. In this study, we introduce the prototype of this new CVT systems, and its force calibration tests. The results indicate that the manufactured CVT is capable of displaying the desired output force throughout its transmission ratio range within a tolerance.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 12
    Geometrical Analysis of a Continuously Variable Transmission System Designed for Human-Robot Interfaces
    (Elsevier, 2019) Mobedi, Emir; Dede, Mehmet İsmet Can
    New robotic systems are placed out of their constrained workspaces in order to work alongside humans. Consequently, these applications call for robots monitoring and regulating physical human-robot interaction. These robots’ mechanical compliance should be varied when they are in physical contact with the human or their changing environments. This compliance variation can be achieved in a variety of ways. However, one common idea is the variation of joint stiffness mechanically, electromechanically or by control. The solution presented in this paper is an electromechanical way of varying the joint stiffness. Among the electromechanical methods for varying the joint stiffness, continuously variable transmission (CVT) systems can be used in human-robot interfaces if a set of design criteria are met. These criteria include backdrivability, independent output position and stiffness variation, shock absorbing and low mass/inertia. In this paper, a novel two-cone CVT design with a double spherical transmission element is introduced by taking into account the abovementioned criteria. Additionally, design parameters are identified via carrying out a geometrical analysis of this new CVT system.
  • Conference Object
    A Continuously Variable Transmission System Designed for Human-Robot Interfaces
    (IFToMM, 2018) Mobedi, Emir; Dede, Mehmet İsmet Can
    Continuously Variable Transmission (CVT) systems are being used for many applications such as automotive transmissions, robotics, aerospace. In an ideal condition, these systems have the potential to provide continuously varying power transmission within a predefined limit. This transmission is accomplished with the help of friction, belt or gear systems. CVT can find application in a human-robot interface if design criteria such as backdrivability, independent output position and impedance variation, shock absorbing and low mass and inertia can be satisfied. Even if there are various CVT designs in the literature for human-robot interfaces, the primary limitation of the two-cone drive CVT designs is that the output torque and the output position cannot be altered independently. The reason for this problem is that the friction wheel, which is designed to transmit the torque from the input cone to the output cone, gives rise to remarkable longitudinal friction force along the linear way. In order to overcome this problem, a sphere is used in this work for the CVT design as the transmission element. In addition, it is stated in the literature that common CVT drive systems do not have the capability to be used in cyclic bidirectional motion. In the presented CVT design, a second sphere is added to the system with two springs from the lower part of the cones for pre-tension in order to solve the bidirectional transmission problem. In this paper, the working principle and conceptual design details of the novel two-cone CVT drive are presented. Experimental results showed that the novel CVT has the capacity to transmit bidirectional power with some accuracy.
  • Book Part
    Citation - WoS: 1
    Citation - Scopus: 2
    Experimental Evaluation of Actuation and Sensing Capabilities of a Haptic Device
    (Springer, 2019) Mobedi, Emir; Görgülü, İbrahimcan; Dede, Mehmet İsmet Can
    Haptic devices are used to increase the telepresence level by providing the sense of touch to the human operator. Simultaneously, they capture the targeted motion of the human operator to generate a motion demand for the teleoperated slave system. Considering a scenario where the slave system’s end-effector is handled by the human operator at the master side, which is attached to the haptic device, an ideal haptic interaction involves the feeling of only the end-effector dynamics and the accurate sensation of the end-effector pose. The performance of a haptic device is based on these two functionalities. In this paper, the experimental evaluation of the actuation and sensing capabilities of a haptic device, HIPHAD v1.0 kinesthetic haptic device, is presented.