Person: BEBEK, Özkan
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Özkan
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BEBEK
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ArticlePublication Metadata only Visual needle tip tracking in 2D US guided robotic interventions(Elsevier, 2019-02) Kaya, M.; Şenel, E.; Ahmad, A.; Bebek, Özkan; Mechanical Engineering; BEBEK, ÖzkanPercutaneous needle procedures are among the most frequently performed minimally invasive surgical procedure. For tracking the needle tip in the tissue, 2D ultrasound (US) imaging is commonly used; however, the low resolution of the images creates a challenge for tracking. This paper describes a robotic system that can perform US image guided biopsies by tracking the needle and the target simultaneously. It uses a template-based visual tracking method for small and deformable targets. During the experiments, a needle was inserted into realistic phantoms using a 5-DOF robot. The 2D US probe was held by a robotic arm that was servoed along the needle path. The 3D shape of the needle was estimated using the 2D transverse US images, which was used to align the needle axis with the 2D imaging plane. The accuracy of the visual needle tip tracking was evaluated using an optical tracking system, and a computed tomography scanner was used to determine the accuracy of the 3D needle shape estimation method. Target reaching accuracies were measured using an electromagnetic tracking system. The results of the experiments showed that the proposed system can track the needle tip in 2D US guided needle procedures in real-time with a sub-millimeter positional error.ArticlePublication Metadata only Heart motion prediction based on adaptive estimation algorithms for robotic assisted beating heart surgery(IEEE, 2013) Tuna, E. E.; Franke, T. J.; Bebek, Özkan; Shiose, A.; Fukamachi, K.; Çavuşoğlu, M. C.; Mechanical Engineering; BEBEK, ÖzkanRobotic-assisted beating heart surgery aims to allow surgeons to operate on a beating heart without stabilizers as if the heart is stationary. The robot actively cancels heart motion by closely following a point of interest (POI) on the heart surface - a process called active relative motion canceling. Due to the high bandwidth of the POI motion, it is necessary to supply the controller with an estimate of the immediate future of the POI motion over a prediction horizon in order to achieve sufficient tracking accuracy. In this paper, two least-squares-based prediction algorithms, using an adaptive filter to generate future position estimates, are implemented and studied. The first method assumes a linear system relation between the consecutive samples in the prediction horizon. On the contrary, the second method performs this parametrization independently for each point over the whole the horizon. The effects of predictor parameters and variations in heart rate on tracking performance are studied with constant and varying heart rate data. The predictors are evaluated using a three-degree-of-freedom (DOF) test bed and prerecorded in vivo motion data. Then, the one-step prediction and tracking performances of the presented approaches are compared with an extended Kalman filter predictor. Finally, the essential features of the proposed prediction algorithms are summarized.Conference paperPublication Metadata only Improving the safety of medical robotic systems(IEEE, 2018-10-09) Dibekçi, Ayşan; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Dibekçi, AyşanThe significance of the robots in the medical field have been increasing rapidly. Humans and robots working together increases the strengths and decreases the limitations of surgical operations. Human life makes safety the most important problem for medical robots, for which there are no universal standards. This paper presents detailed design methods for increasing medical robots' safety by considering issues of sterilization, robot's size, operating room placement of the robot, the robot mechanics, selection of the electromechanical components, drive mechanism, stiffness, sensor redundancy, software application, and hazard identification and analysis. The proposed safety design concepts were put into practice on a surgical robot prototype and the outcomes are discussed.Conference paperPublication Metadata only Needle localization using gabor filtering in 2D ultrasound images(IEEE, 2014) Kaya, Mert; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Kaya, MertIn the percutaneous needle procedures using ultrasound (US) imaging, the needle should be detected precisely to avoid damage to the tissue and to get the samples from the appropriate site. Excessive artifacts and low resolution of the US images make it difficult to detect the needle and its tip. It is possible to enhance the needle image using image processing; and this work proposes a novel needle detection method in 2D US images based on the Gabor filter. This method enhances the needle outline while suppressing the other structures in the image. First, the needle insertion angle is estimated and then the needle trajectory is found with the RANSAC line estimator. The experiments with three different phantoms showed that the algorithm is robust and could work in percutaneous needle procedures using US images.Conference paperPublication Metadata only Real-time needle tip localization in 2D ultrasound images for robotic biopsies(IEEE, 2015) Kaya, Mert; Şenel, Enes; Ahmad, Mirza Awais; Orhan, Orçun; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Kaya, Mert; Şenel, Enes; Ahmad, Mirza Awais; Orhan, OrçunIn this paper, real-time needle tip tracking method using 2D ultrasound (US) images for robotic biopsies is presented. In this method, the needle tip is estimated with the Gabor filter based image processing algorithm, and the estimation noise is reduced with the Kalman filter. This paper also presents the needle tip tracking simulation to test accuracy of the Kalman filter under position misalignments and tissue deformations. In order to execute proposed method in real-time, the bin packing method is used and the processing time is reduced by 56%, without a GPU. The proposed method was tested in four different phantoms and water medium. The accuracy of the needle tip estimation was measured with optical tracking system, and root mean square error (RMS) of the tip position is found to be 1.17 mm. The experiments showed that the algorithm could track the needle tip in real-time.Conference paperPublication Metadata 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 MuttalipIn 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.ArticlePublication Open Access Özyeğin biopsy robot: system integration architecture and motion compensation of a moving target(TÜBİTAK, 2018-05-30) Ahmad, Mirza Awais; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Ahmad, Mirza AwaisThis paper presents the complete system architecture of a robotic biopsy system for real-time operations. The system has individual functional blocks working simultaneously including a 5 DoF parallel robot, ultrasound (US) imaging machine, two robotic manipulators, and a motion capturing system. Details of the real-time functionality of the robotic system components working with spatial and computational synchronization are presented. This paper also deals with a scenario in which the target tissue is moving due to the breathing of the patient. The motion of the needle tip and the target is tracked using US images as feedback. Two types of control laws for target tracking are discussed: traditional feedback control and an optimal control method. Motion compensation is demonstrated by tracking a moving target with the needle tip motion with an RMS error of 0.25 mm.Conference paperPublication Unknown Simulation-based design and locomotion control implementation for a lower body exoskeleton(IEEE, 2022) Derman, Mustafa; Soliman, Ahmed Fahmy; Kuru, Alihan; Çevik, Süleyman Can; Ünal, Ramazan; Bebek, Özkan; Uğurlu, Regaip Barkan; Mechanical Engineering; ÜNAL, Ramazan; BEBEK, Özkan; UĞURLU, Regaip Barkan; Derman, Mustafa; Soliman, Ahmed Fahmy; Kuru, Alihan; Çevik, Süleyman CanThis paper proposes a simulation-based design and locomotion control methodology for an exoskeleton that is aimed at providing assistance to users with ambulatory difficulties. To increase the power-to-weight ratio while satisfying design constraints, we made use of simulation tools to recursively update the initial mechanical design for a finer solution. To this end, a coupled human-exoskeleton model was constructed in MSC ADAMS environment using an average human model and the initial design of the robot. Following this step, dynamic walking control simulations were carried out to determine actuator torques and loading. Using the loading data obtained via simulation experiments, certain mechanical links were optimized such that the portions with no stress concentration were removed without violating safety. Finally, two distinct control implementations were conducted: i) stand-to-sit motion, ii) dynamic walking. As a result, we obtained dynamically consistent motion behavior for both cases, adequately validating the proposed methodology.ArticlePublication Metadata only Transdisciplinarity as a learning challenge: Student experiences and outcomes in an innovative course on wearable and collaborative robotics(IEEE) Kılıç-Bebek, Ebru; Nizamis, K.; Vlutters, M.; Bebek, Özkan; Karapars, Gülhis Zeynep; Ünal, Ramazan; Yılmaz, Deniz; Uğurlu, Regaip Barkan; Industrial Design; Sectoral Education and Professional Development; Mechanical Engineering; Mitchell, J.; BEBEK, Ebru Kılıç; KARAPARS, Gülhis Zeynep; BEBEK, Özkan; ÜNAL, Ramazan; UĞURLU, Regaip Barkan; Yılmaz, DenizContribution: This study provides evidence for the benefit of short online courses for transdisciplinary competence development of graduate students. It shows the significant challenges students face while learning, and provides instructional recommendations to improve students’ learning quality and professionalism. Background: Developing wearable and collaborative robots requires industry collaboration and transdisciplinary competence. Industry’s involvement in long-term programs is becoming infeasible, and the nature of transdisciplinary learning has not been explored to inform instructional practices. Intended Outcomes: This study aimed to provide instructional recommendations based on an in-depth examination of a diverse group of graduate students’ learning and teamwork experiences as well as outcomes in a 5-day online transdisciplinary course. Application Design: 31 graduate students of engineering, industrial design, and health fields from 4 countries participated in online mixed-discipline instructional sessions and teams to address a real industry challenge. A mixed-methods approach was used to examine students’ experiences and learning outcomes based on a competence measure, session participation data, student journal entries, team progress reports, team elaboration visuals, and final team presentations. Findings: Students’ knowledge of industrial design, medical considerations, ethics and standards, effective teamwork, and self-regulated learning were increased. Students’ high motivation helped them deal with the challenges involved. Daily student journals, team reports, and visual elaboration tools were found to be beneficial for determining the challenges and learning quality. The observed student progress within 5 days is promising, making it worthwhile to further explore the benefits of short online courses for increasing graduates’ readiness and establishing university-industry collaborations in education.Conference paperPublication Metadata only Reducing charging costs for electric vehicles with bi-directional charging(IEEE, 2023) Zincircioğlu, Emircan; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Zincircioğlu, EmircanElectric vehicles (EVs) have gained popularity as eco-friendly and energy-efficient modes of transportation. How-ever, the high cost of charging infrastructure remains a significant barrier to the widespread adoption of EVs. Bidirectional charging (BDC) is a promising solution that allows EVs to charge from the grid and supply excess power back to the grid. In this paper, we present a simulation-based study of BDC using MATLAB/Simulink and Simscape to explore the potential of BDC to reduce charging costs. We modeled an EV charging station equipped with BDC capabilities and evaluated the cost savings achieved through BDC under two different scenarios. Our findings suggest that BDC has the potential to reduce charging costs significantly, making EVs more economically viable.