Browsing by Author "Jabeen, Saher"

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    Master ThesisPublicationMetadata only
    Design and implementation of a robust control scheme for a smart joint
    (2017-01) Jabeen, Saher; Bebek, Özkan; Bebek, Özkan; Yapıcı, Güney Güven; Uğurlu, Regaip Barkan; Samur, E.; İpekoğlu, Mehmet; Department of Mechanical Engineering; Jabeen, Saher
    The invention of biomedical tools has made medical treatments more convenient; however, manual insertion of these tools requires years of practice and erroneous insertion into the body may cause ruptures and bleeding. Employing medical tools with smart joints can improve the medical procedures making them less traumatic. In this work, a shape memory alloy (SMA) actuator based joint, also known as smart joint, is controlled using a discrete-time integral sliding mode (DISM) control to guide the motion of a smart joint. Two Nitinol based SMA actuators are used in an antagonistic arrangement to provide bending motion. The controller is designed on the base of a simplified physical model of a single SMA actuator which eliminates the necessity of obtaining an accurate model. A disturbance observer (DOB) is integrated to the controller to compensate the model uncertainties and external disturbances to the system. The bandwidth of SMA actuator is relatively low. Due to the high sampling time of the hardware that is used, a discrete-time controller was designed. An experimental setup is designed to test the proposed controller with position feedback. In experimental results, DISM controller with DOB is shown to be robust against system model uncertainties and external disturbances. Different frequency responses are compared and it is shown that the response of 0.04 Hz can be achieved with RMS tracking error of 0.0112 radians. Multiple joints connected with rigid links are successfully tracked using Electromagnetic Tracking system as the position sensor.
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    ArticlePublicationMetadata only
    Development of an antagonistically actuated smart joint
    (Trans Tech Publications, 2017) Vahidyeganeh, Ali; Şimsek, Görkem Muttalip; Jabeen, Saher; Bebek, Özkan; Yapıcı, Güney Güven; Mechanical Engineering; BEBEK, Özkan; YAPICI, Güney Güven; Vahidyeganeh, Ali; Şimsek, Görkem Muttalip; Jabeen, Saher
    Shape memory alloys with their phase transformation properties; have been broadly implemented in smart structures. In this study, a functional design is presented where two wires actuate antagonistically to achieve motion in bending. Effect of heat treatment parameters on the actuator materials is investigated. For this purpose, a novel experimental test bench appropriate for characterizing a smart joint is presented, and joint performance including actuation force and cyclic behavior are demonstrated. Accordingly, a smart joint configuration capable of 60 degrees bending with a repeatability of 50 cycles is developed.
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    Conference ObjectPublicationMetadata only
    Discrete-time integral sliding mode control of a smart joint for minimally invasive surgeries
    (IEEE, 2016) Jabeen, Saher; Yeganeh, Ali Vahid; Şimsek, Görkem Muttalip; Yapıcı, Güney Güven; Abidi, K.; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; YAPICI, Güney Güven; Jabeen, Saher; Yeganeh, Ali Vahid; Şimsek, Görkem Muttalip
    In this work, a shape memory alloy(SMA) actuator based joint (smart joint) is controlled using a discrete-time integral sliding mode (DISM) control to guide the motion of an active catheter. Controller is designed on the base of a simplified physical model of a single SMA actuator which eliminates the necessity of obtaining an accurate model. SMAs are nonlinear actuators and for this reason, a disturbance observer (DOB) is integrated in to the controller to compensate the model uncertainties and external disturbances to the system. A linearized model is used to design the controller. Bandwidth of SMA actuator is small (response frequency is less than 0.1Hz) and hardware communication frequency is 20Hz. Due to high sampling time (τ= 50ms) it is idealized to design a discrete-time controller, as switching frequency of the controller variable is then limited by τ-1. An experimental setup is designed to test the proposed controller with position feedback. In experimental results, DISM controller with DOB is shown to be robust against system model uncertainties and external disturbances. Different frequency responses are compared and it is shown that the response of 0.04 Hz can be achieved with rms tracking error of 0.0112 radians.