Yazar "Ayyildiz, Mehmet" seçeneğine göre listele

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    Dokunmatik Yüzeylerde Yerel Dokunsal Geri Bildirime Doğru: Piezo Yamalar Tarafından Çalıştırılan Titreşimli Bir Dokunmatik Ekranın Sonlu Elemanlar Analizi
    (Osman SAĞDIÇ, 2021) Alpdoğan, Nur Lara; Ayyildiz, Mehmet
    Yüzey haptik teknolojileri, parmak ve dokunmatik ekran arasında benzersiz ve ayırt edici bir etkileşim sağlayarak artırılmış bir kullanıcı deneyimi sunar. Bu çalışmada, yüzeyinde bulunan piezo yamalar aracılığıyla kullanıcıya vibrotaktil dokunsal geri bildirim gösteren bir dokunmatik ekran tasarımına odaklanılmıştır. ANSYS FEM yazılım paketini kullanarak, dokunmatik yüzeyde en yüksek deformasyonu sağlayacak ekran ve piezo yama malzemelerinin, sınır koşullarının ve piezo konfigürasyonunun etkilerini insan dokunsal algısının en hassas olacağı frekansı göz önünde bulundurarak araştırdık. Analizimizde üç farklı dokunmatik yüzey ve piezo yama malzemesi, üç farklı sınır koşulu, dört farklı piezo konumu ve üç farklı dokunmatik yüzey kalınlığı kullandık. Sonuçlar, camın sınır koşullarının ve kalınlığının dokunmatik yüzeyin ilk doğal frekansı üzerinde önemli bir etkiye sahip olduğunu ve dokunmatik yüzeyin dört tarafına dört piezo yamasının sabitlenmesiyle en iyi insan dokunma algısını sağlayacak sonuçların elde edildiğini gösterdiModal analizlerde belirlenen konfigürasyon baz alınarak, dokunmatik ekranda maksimum deformasyonun başarılacağı dokunmatik ekranın geometrisini (genişlik, yükseklik, kalınlık) hesaplamak için bir tepki yüzeyi optimizasyonu çalışması gerçekleştirdik. 160 × 90 × 0.28 mm ve 190 × 110 × 0.4 mm boyutlarıyla en iyi konfigürasyonu (yaklaşık 250 Hz birinci modal frekansta maksimum toplam deformasyon) elde ettik. Gelecekte, FEM simülasyonlarının sonuçlarına bağlı olarak tahmin edilecek değişik piezo kombinasyonlarında (tahrik sırası, genliği, ve frekansı) dokunmatik yüzeylerde yerelleştirilmiş dokunsal geri bildirim oluşturacak modeller geliştireceğiz.|Surface haptics technologies offer an augmented user experience by providing a unique and distinctive interaction between the finger and touchscreen. In this study, we focus on a touch screen design to display vibrotactile tactile feedback to the user through piezo patches located on its surface. We investigated the effects of boundary conditions, piezo configurations, and materials of the touch surface and piezo patches that will achieve the highest deformation on the touch surface, considering the most sensible human tactile perception frequency using the ANSYS FEM software package. In our analysis, we used three different touch surface and piezo patch materials, three different boundary conditions, four different piezo patch locations, and three different touch surface thicknesses. The results showed that the boundary conditions and thickness of the glass have a significant effect on the first natural frequency of the touch surface, and the results leading to best human tactile perception were obtained by fixing four piezo patches at four sides of the touch surface. Based on the determined configuration in the modal analyses, we performed a response surface optimization study to estimate the geometry of the touch surface (width, height, thickness), which will result in maximum deformation on the touch surface. We achieved the best configuration (max total deformation at about 250 Hz first modal frequency) with 160 × 90 × 0.28 mm and 190 × 110 × 0.4 mm dimensions. In the future, we will develop models to render localized tactile feedback on a touchscreen-based on piezo patches operating at various combinations (i.e., sequence, amplitude, frequency), which will be predicted based on the FEM simulations.
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    Effect of Finger Velocity on Frictional Forces Modulated by Electrovibration
    (IEEE, 2017) Sirin, Omer; Ayyildiz, Mehmet; Basdogan, Cagatay
    We investigate the effect of sliding velocity on frictional forces between human finger and a touch screen actuated by electrostatic forces. For this purpose, we command a motorized slider to move human finger back and forth (one stroke) in horizontal direction at 9 different velocities (2, 5, 10, 20, 30, 40, 50, 60, 70 mm/s) while the finger is in contact with the touch screen and record the tangential forces for the normal forces varied in a controlled manner from 0.1 N to 0.9 N. During the experiments, the electrostatic forces were turned ON and OFF after every other stroke. The results of the experiments show that the data can be categorized into two groups: 1) stickslip and 2) sliding, which occurs at velocities higher than and equal to 30 mm/s. After grouping, we fit a nonlinear function in the form of F = aF to the sliding data recorded for the OFF and ON conditions. Using the fit functions, we show that the magnitude of the electrostatic forces increases from 50 to 310 mN as the normal force is increased from 0.1 N to 0.9 N.
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    Haptic Perception of 2D Equilateral Geometric Shapes via Electrovibration on Touch Screen
    (IEEE, 2017) Sadic, Ayberk; Ayyildiz, Mehmet; Basdogan, Cagatay
    Haptic feedback is a potential technology to convey spatial, graphical, or pictorial information to visually impaired people that is difficult to be transmitted verbally. In this study, we investigated the effects of edge number (N) and rendering technique on haptic recognition of two-dimensional (2D) equilateral geometric shapes displayed by electrovibration on touch screens. We conducted experiments with 9 subjects using 5 shapes (triangle, square, pentagon, hexagon, and octagon) under 3 different experimental conditions; 1) electrovibration was displayed inside the shapes (INSIDE condition), 2) on their edges (EDGE condition), and 3) at the outside of the shapes (OUTSIDE condition). We observed that haptic recognition accuracy of the subjects decreased as the number of edges was increased from N=3 (triangle) to N=6 (hexagon). Surprisingly, the recognition accuracy for the octagon (N=8) was significantly higher than that of the hexagon. The results also showed that there was no significant difference in rendering techniques in terms of the recognition rates, but displaying electrovibration inside the shapes (INSIDE condition) led to the shortest duration of haptic recognition.