Browsing by Author "Sarac, Mine"
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Conference Object Citation Count: 0Effect of Grip Style on Peripersonal Target Pointing in VR Head Mounted Displays(Ieee Computer Soc, 2023) Batmaz, Anil Ufuk; Turkmen, Rumeysa; Sarac, Mine; Machuca, Mayra Donaji Barrera; Stuerzlinger, WolfgangWhen working in Virtual Reality (VR), the user's performance is affected by how the user holds the input device (e.g., controller), typically using either a precision or a power grip. Previous work examined these grip styles for 3D pointing at targets at different depths in peripersonal space and found that participants had a lower error rate with the precision grip but identified no difference in movement speed, throughput, or interaction with target depth. Yet, this previous experiment was potentially affected by tracking differences between devices. This paper reports an experiment that partially replicates and extends the previous study by evaluating the effect of grip style on the 3D selection of nearby targets with the same device. Furthermore, our experiment re-investigates the effect of the vergence-accommodation conflict (VAC) present in current stereo displays on 3D pointing in peripersonal space. Our results show that grip style significantly affects user performance. We hope that our results are useful for researchers and designers when creating virtual environments.Conference Object Citation Count: 0Effects of Opaque, Transparent and Invisible Hand Visualization Styles on Motor Dexterity in a Virtual Reality Based Purdue Pegboard Test(Ieee Computer Soc, 2023) Voisard, Laurent; Hatira, Amal; Sarac, Mine; Kersten-Oertel, Marta; Batmaz, Anil UfukThe virtual hand interaction technique is one of the most common interaction techniques used in virtual reality (VR) systems. A VR application can be designed with different hand visualization styles, which might impact motor dexterity. In this paper, we aim to investigate the effects of three different hand visualization styles transparent, opaque, and invisible - on participants' performance through a VR-based Purdue Pegboard Test (PPT). A total of 24 participants were recruited and instructed to place pegs on the board as quickly and accurately as possible. The results indicated that using the invisible hand visualization significantly increased the number of task repetitions completed compared to the opaque hand visualization. However, no significant difference was observed in participants' preference for the hand visualization styles. These findings suggest that an invisible hand visualization may enhance performance in the VR-based PPT, potentially indicating the advantages of a less obstructive hand visualization style. We hope our results can guide developers, researchers, and practitioners when designing novel virtual hand interaction techniques.Article Citation Count: 0Hand Dominance and Congruence for Wrist-Worn Haptics Using Custom Voice-Coil Actuation(Ieee-inst Electrical Electronics Engineers inc, 2024) Adeyemi, Ayoade; Sen, Umit; Ercan, Samet Mert; Sarac, MineDuring virtual interactions, rendering haptic feedback on a remote location (like the wrist) instead of the fingertips frees users' hands from mechanical devices. This allows for real interactions while still providing information about the mechanical properties of virtual objects. In this letter, we investigate the impact of using the dominant or non-dominant hand for virtual interactions and the best mapping between the active hand and the wrist receiving the haptic feedback, which can be defined as hand-wrist congruence through a user experiment based on a stiffness discrimination task. To render force feedback, we present CoWrHap - a novel wrist-worn haptic device with custom-made voice coil actuation. Our results show that participants performed the tasks (i) better with non-congruent mapping but reported better experiences with congruent mapping, and (ii) with no statistical difference in terms of hand dominance but with better user experience (enjoyment, pleasantness, etc.) using their dominant hands.Conference Object Citation Count: 2Haptic Feedback Relocation from the Fingertips to the Wrist for Two-Finger Manipulation in Virtual Reality(IEEE, 2022) Palmer, Jasmin E.; Sarac, Mine; Garza, Aaron A.; Okamura, Allison M.Relocation of haptic feedback from the fingertips to the wrist has been considered as a way to enable haptic interaction with mixed reality virtual environments while leaving the fingers free for other tasks. We present a pair of wrist-worn tactile haptic devices and a virtual environment to study how various mappings between fingers and tactors affect task performance. The haptic feedback rendered to the wrist reflects the interaction forces occurring between a virtual object and virtual avatars controlled by the index finger and thumb. We performed a user study comparing four different finger-totactor haptic feedback mappings and one no-feedback condition as a control. We evaluated users' ability to perform a simple pick-and-place task via the metrics of task completion time, path length of the fingers and virtual cube, and magnitudes of normal and shear forces at the fingertips. We found that multiple mappings were effective, and there was a greater impact when visual cues were limited. We discuss the limitations of our approach and describe next steps toward multi-degreeof-freedom haptic rendering for wrist-worn devices to improve task performance in virtual environments.Conference Object Citation Count: 1The Impact of Haptic Feedback During Sudden, Rapid Virtual Interactions(Ieee, 2023) Tanacar, Nizamettin T.; Mughrabi, Moaaz H.; Batmaz, Anil U.; Leonardis, Daniele; Sarac, MineHaptic feedback is known to improve the realism and the performance of virtual tasks during manipulation or teleoperation tasks. However, these benefits might depend on the nature of virtual tasks or the intensity of haptic rendering. In this paper, we focused on the impact of the presence and the intensity of the haptic stimulus during sudden, rapid virtual interactions through a variation of an ISO 9241:411 - task instead of calm, exploration-based interactions. We conducted a user study where the haptic stimulus is rendered through a realistic 1-DoF fingertip haptic device with different intensity levels (full-strength, half-strength, and no-strength) as they are asked to choose highlighted targets on a 6-by-5 grid as fast and correctly as possible. Our results show that haptic feedback did not significantly affect user performance regarding time, throughput, or the nature of the selection behavior. However, participants made significantly more errors when haptic feedback was present in half-strength compared to full-strength and no-strength conditions. In the post-experiment questionnaire, participants reported having favored haptic feedback in full strength in terms of perceived realism, enjoyment, and immersion.Conference Object Citation Count: 3Measuring the Effect of Stereo Deficiencies on Peripersonal Space Pointing(IEEE Computer Soc, 2023) Batmaz, Anil Ufuk; Mughribi, Moaaz Hudhud; Sarac, Mine; Machuca, Mayra Barrera; Stuerzlinger, WolfgangState-of-the-art Virtual Reality (VR) and Augmented Reality (AR) headsets rely on singlefocal stereo displays. For objects away from the focal plane, such displays create a vergence-accommodation conflict (VAC), potentially degrading user interaction performance. In this paper, we study how the VAC affects pointing at targets within arm's reach with virtual hand and raycasting interaction in current stereo display systems. We use a previously proposed experimental methodology that extends the ISO 9241-411:2015 multi-directional selection task to enable fair comparisons between selecting targets in different display conditions. We conducted a user study with eighteen participants and the results indicate that participants were faster and had higher throughput in the constant VAC condition with the virtual hand. We hope that our results enable designers to choose more efficient interaction methods in virtual environments.Review Citation Count: 1Optimizing Exoskeleton Design with Evolutionary Computation: An Intensive Survey(Mdpi, 2023) Stroppa, Fabıo; Soylemez, Aleyna; Yuksel, Huseyin Taner; Akbas, Baris; Sarac, MineExoskeleton devices are designed for applications such as rehabilitation, assistance, and haptics. Due to the nature of physical human-machine interaction, designing and operating these devices is quite challenging. Optimization methods lessen the severity of these challenges and help designers develop the device they need. In this paper, we present an extensive and systematic literature search on the optimization methods used for the mechanical design of exoskeletons. We completed the search in the IEEE, ACM, and MDPI databases between 2017 and 2023 using the keywords exoskeleton, design, and optimization. We categorized our findings in terms of which limb (i.e., hand, wrist, arm, or leg) and application (assistive, rehabilitation, or haptic) the exoskeleton was designed for, the optimization metrics (force transmission, workspace, size, and adjustability/calibration), and the optimization method (categorized as evolutionary computation or non-evolutionary computation methods). We discuss our observations with respect to how the optimization methods have been implemented based on our findings. We conclude our paper with suggestions for future research.Article Citation Count: 6Perceived Intensities of Normal and Shear Skin Stimuli Using a Wearable Haptic Bracelet(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Sarac, Mine; Huh, Tae Myung; Choi, Hojung; Cutkosky, Mark R.; Di Luca, Massimiliano; Okamura, Allison M.Our aim is to provide effective interaction with virtual objects, despite the lack of co-location of virtual and real-world contacts, while taking advantage of relatively large skin area and ease of mounting on the forearm. We performed two human participant studies to determine the effects of haptic feedback in the normal and shear directions during virtual manipulation using haptic devices worn near the wrist. In the first study, participants performed significantly better while discriminating stiffness values of virtual objects when the feedback consisted of normal displacements compared to shear displacements. Participants also commented that they could detect normal cues much easier than shear, which motivated us to perform a second study to find the point of subjective equality (PSE) between normal and shear stimuli. Our results show that shear stimuli require a larger actuator displacement but less force than normal stimuli to achieve perceptual equality for our haptic bracelets. We found that normal and shear stimuli cannot be equalized through skin displacement nor the interaction forces across all users. Rather, a calibration method is needed to find the point of equality for each user where normal and shear stimuli create the same intensity on the user's skin.Conference Object Citation Count: 1Perception of Mechanical Properties via Wrist Haptics: Effects of Feedback Congruence(IEEE, 2022) Sarac, Mine; Di Luca, Massimiliano; Okamura, Allison M.Despite non-co-location, haptic stimulation at the wrist can potentially provide feedback regarding interactions at the fingertips without encumbering the user's hand. Here we investigate how two types of skin deformation at the wrist (normal and shear) relate to the perception of the mechanical properties of virtual objects. We hypothesized that a congruent mapping (i.e. when the most relevant interaction forces during a virtual interaction spatially match the haptic feedback at the wrist) would result in better perception than other mappings.We performed an experiment where haptic devices at the wrist rendered either normal or shear feedback during manipulation of virtual objects with varying stiffness, mass, or friction properties. Perception of mechanical properties was more accurate with congruent skin stimulation than noncongruent. In addition, discrimination performance and subjective reports were positively influenced by congruence. This study demonstrates that users can perceive mechanical properties via haptic feedback provided at the wrist with a consistent mapping between haptic feedback and interaction forces at the fingertips, regardless of congruence.Conference Object Citation Count: 2Re-investigating the Effect of the Vergence-Accommodation Conflict on 3D Pointing(Assoc Computing Machinery, 2023) Batmaz, Anil Ufuk; Turkmen, Rumeysa; Sarac, Mine; Machuca, Mayra Donaji Barrera; Stuerzlinger, WolfgangThe vergence-accommodation conflict (VAC) limits user performance in current Virtual Reality (VR) systems. In this paper, we investigate the effects of the VAC in a single-focal VR system using three experimental conditions: with no VAC, with a constant VAC, and with a varying VAC. Previous work in this area had yielded conflicting results, so we decided to re-investigate this issue. Eighteen participants performed an ISO 9241:411 task in a study that closely replicates previous work, except that the angle of the task space was rotated 20 degrees downward, to make the task less fatiguing to perform, which addresses a potential confound in previous work. We found that the varying VAC condition had worse performance than the other conditions, which indicates that the contrasting results in previous work were very likely due to biomechanical factors. We hope that our work contributes to the understanding of the influence of the VAC in VR systems and potential strategies for improving user experience and performance in immersive virtual environments.Article Citation Count: 0Touch to Learn: A Review of Haptic Technology's Impact on Skill Development and Enhancing Learning Abilities for Children(Wiley, 2024) Hatira, Amal; Sarac, MineEarly childhood education is critical in shaping children's intellectual and motor skills as it provides a solid foundation for cognitive, social, and emotional development, which highly depends on spatial thinking. Haptic feedback can be effectively used for educational and training purposes, particularly in fields such as physics, math, and arts, offering a more interactive learning media and supporting kinesthetic learners by its nature. Herein, different ways of implementing haptic feedback on different educational scenarios from the perspective of technological development and their impact on children's learned skills and outcomes (e.g., their motivation, their analytical or spatial thinking abilities, or fine motor skills) will be examined. This article provides an overview of how haptic feedback has been implemented in different learning scenarios for children. Particularly, it is indicated that haptics can potentially improve early childhood learning outcomes and spatial reasoning skills as it can increase children's interest, participation, performance in educational activities, and analytical ability. The major drawbacks of the current studies, such as variance in participants' learning challenges and small sample numbers are also highlighted. Haptic feedback can be used for educationand training , offering a more interactive learning media and supporting kinesthetic learners by its nature. Herein, we provide an overview of how haptic feedback has been implemented in different learning scenarios for children from the perspective of technological development and their impact on learned skills, achieved motivation, thinking abilities, or fine motor skills.image (c) 2024 WILEY-VCH GmbH