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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6
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Publication Open Access Supporting negotiation behavior with haptics-enabled human-computer interfaces(Institute of Electrical and Electronics Engineers (IEEE), 2012) Department of Mechanical Engineering; Küçükyılmaz, Ayşe; Sezgin, Tevfik Metin; Başdoğan, Çağatay; PhD Student; Faculty Member; Faculty Member; Department of Mechanical Engineering; College of Engineering; N/A; 18632; 125489; N/AAn active research goal for human-computer interaction is to allow humans to communicate with computers in an intuitive and natural fashion, especially in real-life interaction scenarios. One approach that has been advocated to achieve this has been to build computer systems with human-like qualities and capabilities. In this paper, we present insight on how human-computer interaction can be enriched by employing the computers with behavioral patterns that naturally appear in human-human negotiation scenarios. For this purpose, we introduce a two-party negotiation game specifically built for studying the effectiveness of haptic and audio-visual cues in conveying negotiation related behaviors. The game is centered around a real-time continuous two-party negotiation scenario based on the existing game-theory and negotiation literature. During the game, humans are confronted with a computer opponent, which can display different behaviors, such as concession, competition, and negotiation. Through a user study, we show that the behaviors that are associated with human negotiation can be incorporated into human-computer interaction, and the addition of haptic cues provides a statistically significant increase in the human-recognition accuracy of machine-displayed behaviors. In addition to aspects of conveying these negotiation-related behaviors, we also focus on and report game-theoretical aspects of the overall interaction experience. In particular, we show that, as reported in the game-theory literature, certain negotiation strategies such as tit-for-tat may generate maximum combined utility for the negotiating parties, providing an excellent balance between the energy spent by the user and the combined utility of the negotiating parties.Publication Open Access On the rate of convergence of a classifier based on a transformer encoder(Institute of Electrical and Electronics Engineers (IEEE), 2022) Gurevych, Iryna; Kohler, Michael; Department of Computer Engineering; Şahin, Gözde Gül; Faculty Member; Department of Computer Engineering; College of Engineering; 366984Pattern recognition based on a high-dimensional predictor is considered. A classifier is defined which is based on a Transformer encoder. The rate of convergence of the misclassification probability of the classifier towards the optimal misclassification probability is analyzed. It is shown that this classifier is able to circumvent the curse of dimensionality provided the a posteriori probability satisfies a suitable hierarchical composition model. Furthermore, the difference between the Transformer classifiers theoretically analyzed in this paper and the ones used in practice today is illustrated by means of classification problems in natural language processing.Publication Open Access Tactile masking by electrovibration(Institute of Electrical and Electronics Engineers (IEEE), 2018) Güçlü, Burak; Department of Mechanical Engineering; Başdoğan, Çağatay; Vardar, Yasemin; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; 125489; N/AFuture touch screen applications will include multiple tactile stimuli displayed simultaneously or consecutively to single finger or multiple fingers. These applications should be designed by considering human tactile masking mechanism since it is known that presenting one stimulus may interfere with the perception of the other. In this study, we investigate the effect of masking on the tactile perception of electrovibration displayed on touch screens. Through conducting psychophysical experiments with nine participants, we measured the masked thresholds of sinusoidal electrovibration bursts (125 Hz) under two masking conditions: simultaneous and pedestal. The masking signals were noise bursts, applied at five different sensation levels varying from 2 to 22 dB SL, also presented by electrovibration. For each participant, the thresholds were elevated as linear functions of masking levels for both masking types. We observed that the masking effectiveness was larger with pedestal masking than simultaneous masking. Moreover, in order to investigate the effect of tactile masking on our haptic perception of edge sharpness, we compared the perceived sharpness of edges separating two textured regions displayed with and without various types of masking stimuli. Our results suggest that sharpness perception depends on the local contrast between background and foreground stimuli, which varies as a function of masking amplitude and activation levels of frequency-dependent psychophysical channels.Publication Open Access Special issue on surface haptics(Institute of Electrical and Electronics Engineers (IEEE), 2020) Giraud, Frederic; Levesque, Vincent; Choi, Seungmoon; Department of Mechanical Engineering; Başdoğan, Çağatay; Faculty Member; Department of Mechanical Engineering; College of Engineering; 125489Publication Open Access Frequency-dependent behavior of electrostatic forces between human finger and touch screen under electroadhesion(Institute of Electrical and Electronics Engineers (IEEE), 2022) Department of Mechanical Engineering; Başdoğan, Çağatay; Aliabbasi, Easa; Alipour, Mohammad; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; 125489; N/A; N/AThe existing lumped parameter circuit models do not capture the true (experimentally observed) behavior of electrostatic forces between human finger and a touch screen under electroadhesion, changing as a function of stimulation frequency. In order to address this problem, we first conducted an experiment to measure the voltage-induced frictional forces acting on the finger of a user sliding on a touch screen under constant normal force for stimulation frequencies ranging from 1 to 106 Hz. The steady-state values of coefficient of sliding friction for those frequencies and the value for voltage-free sliding (no electroadhesion) were utilized to estimate the magnitude of electrostatic force as a function of frequency. The experimental data shows that electrostatic force follows an inverted parabolic curve with a peak value around 250 Hz. Following the experimental characterization of electrostatic forces, an electromechanical model based on the fundamental laws of electric fields and Persson's multi-scale contact mechanics theory was developed. Compared to the existing ones in the literature, the proposed model takes into account the charge accumulation and transfer at the interfaces of finger and touch screen. The model is in good agreement with the experimental data and shows that the change in magnitude of electrostatic force is mainly due to the leakage of charge from the Stratum Corneum (SC) to the touch screen at frequencies lower than 250 Hz and electrical properties of the SC at frequencies higher than 250 Hz.Publication Open Access Fundamentals of green communications and computing: modeling and simulation(Institute of Electrical and Electronics Engineers (IEEE), 2012) Department of Electrical and Electronics Engineering; Akan, Özgür Barış; Malak, Derya; Kocaoğlu, Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of EngineeringA layered architecture incorporates the concept of minimum energy consumption for communication links and computer networks with multiple terminals, where emission-reduction approaches based on information theory are impractical.Publication Open Access An optoelectromechanical tactile sensor for detection of breast lumps(Institute of Electrical and Electronics Engineers (IEEE), 2013) Yıldız, Mustafa Zahid; Güçlü, Burak; Department of Mechanical Engineering; Başdoğan, Çağatay; Ayyıldız, Mehmet; Faculty Member; Master Student; Department of Mechanical Engineering; College of Engineering; 125489; N/AWe developed a compact tactile imaging (TI) system to guide the clinician or the self-user for noninvasive detection of breast tumors. Our system measures the force distribution based on the difference in stiffness between a palpated object and an abnormality within. The average force resolution, force range, and the spatial resolution of the device are 0.02 N, 0-4 N, and 2.8 mm, respectively. To evaluate the performance of the proposed TI system, compression experiments were performed to measure the sensitivity and specificity of the system in detecting tumor-like inclusions embedded in tissue-like cylindrical silicon samples. Based on the experiments performed with 11 inclusions, having two different sizes and two different stiffnesses located at three different depths, our TI system showed an average sensitivity of 90.8 +/- 8.1 percent and an average specificity of 89.8 +/- 12.7 percent. Finally, manual palpation experiments were performed with 12 human subjects on the same silicon samples and the results were compared to that of the TI system. The performance of the TI system was significantly better than that of the human subjects in detecting deep inclusions while the human subjects performed slightly better in detecting shallow inclusions close to the contact surface.Publication Open Access A novel haptic feature set for the classification of interactive motor behaviors in collaborative object transfer(Institute of Electrical and Electronics Engineers (IEEE), 2021) Küçükyılmaz, Ayşe; Department of Mechanical Engineering; Başdoğan, Çağatay; Şirintuna, Doğanay; Al-Saadi, Zaid Rassim Mohammed; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; 125489; N/A; N/AHaptics provides a natural and intuitive channel of communication during the interaction of two humans in complex physical tasks, such as joint object transportation. However, despite the utmost importance of touch in physical interactions, the use of haptics is under-represented when developing intelligent systems. This article explores the prominence of haptic data to extract information about underlying interaction patterns within physical human-human interaction (pHHI). We work on a joint object transportation scenario involving two human partners, and show that haptic features, based on force/torque information, suffice to identify human interactive behavior patterns. We categorize the interaction into four discrete behavior classes. These classes describe whether the partners work in harmony or face conflicts while jointly transporting an object through translational or rotational movements. In an experimental study, we collect data from 12 human dyads and verify the salience of haptic features by achieving a correct classification rate over 91% using a Random Forest classifier.Publication Open Access Modeling and analysis of vessel casualties resulting from tanker traffic through narrow waterways(Wiley, 1999) Otay, Emre N.; Department of Business Administration; Tan, Barış; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; 28600In this paper, we present a physics-based stochastic model to investigate vessel casualties resulting from tanker traffic through a narrow waterway. A state-space model is developed to represent the waterway and the location of vessels at a given time. We first determine the distribution of surface current at a given location of the waterway depending on channel geometry, bottom topography, boundary conditions, and the distribution of wind. Then we determine the distribution of the angular drift for a given vessel travelling at a given location of a waterway. Finally, we incorporate the drift probabilities and random arrival of vessels into a Markov chain model. By analyzing the time-dependent and the steady-state probabilities of the Markov chain, we obtain risk measures such as the probability of casualty at a given location and also the expected number of casualties for a given number of vessels arriving per unit time. Analysis of the Markovian model also yields an analytical result that shows that the expected number of casualties is proportional to square of the tanker arrival rate. We present our methodology on an experimental model of a hypothetical narrow waterway.Publication Open Access Psychophysical evaluation of change in friction on an ultrasonically-actuated touchscreen(Institute of Electrical and Electronics Engineers (IEEE), 2018) Yılmaz, Çetin; Department of Mechanical Engineering; Başdoğan, Çağatay; Saleem, Muhammad Khurram; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; 125489; N/ATo render tactile cues on a touchscreen by friction modulation, it is important to understand how humans perceive a change in friction. In this study, we investigate the relations between perceived change in friction on an ultrasonically actuated touchscreen and parameters involved in contact between finger and its surface. We first estimate the perceptual thresholds to detect rising and falling friction while a finger is sliding on the touch surface. Then, we conduct intensity scaling experiments and investigate the effect of finger sliding velocity, normal force, and rise/fall time of vibration amplitude (transition time) on the perceived intensity of change in friction. In order to better understand the role of contact mechanics, we also look into the correlations between the perceived intensities of subjects and several parameters involved in contact. The results of our experiments show that the contrast and rate of change in tangential force were best correlated with the perceived intensity. The subjects perceived rising friction more strongly than falling friction, particularly at higher tangential force contrast. We argue that this is due to hysteresis and viscoelastic behavior of fingertip under tangential loading. The results also showed that transition time and normal force have significant effect on our tactile perception..