Browsing by Author "Sarac, Mine"

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Citation Count: 0
Effect of Grip Style on Peripersonal Target Pointing in VR Head Mounted Displays
(Ieee Computer Soc, 2023) Batmaz, Anıl Ufuk; Turkmen, Rumeysa; Sarac, Mine; Machuca, Mayra Donaji Barrera; Stuerzlinger, Wolfgang
When 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.
Citation Count: 0
Effect of Hand and Object Visibility in Navigational Tasks Based on Rotational and Translational Movements in Virtual Reality
(Ieee Computer Soc, 2024) Batmaz, Anıl Ufuk; Gelmez, Zeynep Ecem; Batmaz, Anil Ufuk; Sarac, Mine
During object manipulation in Virtual Reality (VR) systems, realistically visualizing avatars and objects can hinder user performance and experience by complicating the task or distracting the user from the environment due to possible occlusions. Users might feel the urge to go through biomechanical changes, such as re-positioning the head to visualize the interaction area. In this paper, we investigate the effect of hand avatar and object visibility in navigational tasks using a VR headset. We performed two user studies where participants grasped a small, cylindrical object and navigated it through the virtual obstacles performing rotational or translational movements. We used three different visibility conditions for the hand avatar (opaque, transparent, and invisible) and two conditions for the object (opaque and transparent). Our results indicate that participants performed faster and with fewer collisions using the invisible and transparent hands compared to the opaque hand and fewer collisions with the opaque object compared to the transparent one. Furthermore, participants preferred to use the combination of the transparent hand avatar with the opaque object. The findings of this study might be useful to researchers and developers in deciding the visibility/transparency conditions of hand avatars and virtual objects for tasks that require precise navigational activities.
Citation Count: 0
Effects of Opaque, Transparent and Invisible Hand Visualization Styles on Motor Dexterity in a Virtual Reality Based Purdue Pegboard Test
(Ieee Computer Soc, 2023) Batmaz, Anıl Ufuk; Hatira, Amal; Sarac, Mine; Kersten-Oertel, Marta; Batmaz, Anil Ufuk
The 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.
Citation Count: 0
Eye-Hand Coordination Training: A Systematic Comparison of 2D, VR, and AR Display Technologies and Task Instructions
(Ieee Computer Soc, 2024) Batmaz, Anıl Ufuk; Zaugg, Irene; Celik, Elif; Stuerzlinger, Wolfgang; Ortega, Francisco Raul; Batmaz, Anil Ufuk; Sarac, Mine
Previous studies on Eye-Hand Coordination Training (EHCT) focused on the comparison of user motor performance across different hardware with cross-sectional studies. In this paper, we compare user motor performance with an EHCT setup in Augmented Reality (AR), Virtual Reality (VR), and on a 2D touchscreen display in a longitudinal study. Through a ten-day user study, we thoroughly analyzed the motor performance of twenty participants with five task instructions focusing on speed, error rate, accuracy, precision, and none. As a novel evaluation criterion, we also analyzed the participants' performance in terms of effective throughput. The results showed that each task instruction has a different effect on one or more psychomotor characteristics of the trainee, which highlights the importance of personalized training programs. Regarding different display technologies, the majority of participants could see more improvement in VR than in 2D or AR. We also identified that effective throughput is a good candidate for monitoring overall motor performance progress in EHCT systems.
Citation Count: 0
EyeGuide & EyeConGuide: Gaze-based Visual Guides to Improve 3D Sketching Systems
(Assoc Computing Machinery, 2024) Batmaz, Anıl Ufuk; Gelmez, Zeynep Ecem; Batmaz, Anil Ufuk; Stuerzlinger, Wolfgang; Asente, Paul; Sarac, Mine
Visual guides help to align strokes and raise accuracy in Virtual Reality (VR) sketching tools. Automatic guides that appear at relevant sketching areas are convenient to have for a seamless sketching with a guide. We explore guides that exploit eye-tracking to render them adaptive to the user's visual attention. EYEGUIDE and EYECONGUIDE cause visual grid fragments to appear spatially close to the user's intended sketches, based on the information of the user's eye-gaze direction and the 3D position of the hand. Here we evaluated the techniques in two user studies across simple and complex sketching objectives in VR. The results show that gaze-based guides have a positive effect on sketching accuracy, perceived usability and preference over manual activation in the tested tasks. Our research contributes to integrating gaze-contingent techniques for assistive guides and presents important insights into multimodal design applications in VR.
Citation Count: 0
Hand 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, Mine
During 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.
Citation Count: 2
Haptic 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.
Citation Count: 1
The Impact of Haptic Feedback During Sudden, Rapid Virtual Interactions
(Ieee, 2023) Batmaz, Anıl Ufuk; Mughrabi, Moaaz H.; Batmaz, Anil U.; Leonardis, Daniele; Sarac, Mine
Haptic 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.
Citation Count: 3
Measuring the Effect of Stereo Deficiencies on Peripersonal Space Pointing
(IEEE Computer Soc, 2023) Batmaz, Anıl Ufuk; Mughribi, Moaaz Hudhud; Sarac, Mine; Machuca, Mayra Barrera; Stuerzlinger, Wolfgang
State-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.
Citation Count: 1
Optimizing Exoskeleton Design with Evolutionary Computation: An Intensive Survey
(Mdpi, 2023) Stroppa, Fabıo; Soylemez, Aleyna; Yuksel, Huseyin Taner; Akbas, Baris; Sarac, Mine
Exoskeleton 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.
Citation Count: 0
Optimizing soft robot design and tracking with and without evolutionary computation: an intensive survey
(Cambridge Univ Press, 2024) Stroppa, Fabıo; Majeed, Fatimah Jabbar; Batiya, Jana; Baran, Eray; Sarac, Mine
Soft robotic devices are designed for applications such as exploration, manipulation, search and rescue, medical surgery, rehabilitation, and assistance. Due to their complex kinematics, various and often hard-to-define degrees of freedom, and nonlinear properties of their material, designing and operating these devices can be quite challenging. Using tools such as optimization methods can improve the efficiency of these devices and help roboticists manufacture the robots they need. In this work, we present an extensive and systematic literature search on the optimization methods used for the mechanical design of soft robots, particularly focusing on literature exploiting evolutionary computation (EC). We completed the search in the IEEE, ACM, Springer, SAGE, Elsevier, MDPI, Scholar, and Scopus databases between 2009 and 2024 using the keywords "soft robot," "design," and "optimization." We categorized our findings in terms of the type of soft robot (i.e., bio-inspired, cable-driven, continuum, fluid-driven, gripper, manipulator, modular), its application (exploration, manipulation, surgery), the optimization metrics (topology, force, locomotion, kinematics, sensors, and energy), and the optimization method (categorized as EC or non-EC methods). After providing a road map of our findings in the state of the art, we offer our observations concerning the implementation of the optimization methods and their advantages. We then conclude our paper with suggestions for future research.
Citation Count: 6
Perceived 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.
Citation Count: 1
Perception 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.
Citation Count: 2
Re-investigating the Effect of the Vergence-Accommodation Conflict on 3D Pointing
(Assoc Computing Machinery, 2023) Batmaz, Anıl Ufuk; Turkmen, Rumeysa; Sarac, Mine; Machuca, Mayra Donaji Barrera; Stuerzlinger, Wolfgang
The 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.
Citation Count: 0
Subtask-Based Virtual Hand Visualization Method for Enhanced User Accuracy in Virtual Reality Environments
(Ieee Computer Soc, 2024) Batmaz, Anıl Ufuk; Hatira, Amal; Bashar, Mohammad Raihanul; Gemici, Mucahit; Sarac, Mine; Kersten-Oertel, Marta; Batmaz, Anil Ufuk
In the virtual hand interaction techniques, the opacity of the virtual hand avatar can potentially obstruct users' visual feedback, leading to detrimental effects on accuracy and cognitive load. Given that the cognitive load is related to gaze movements, our study focuses on analyzing the gaze movements of participants across opaque, transparent, and invisible hand visualizations in order to create a new interaction technique. For our experimental setup, we used a Purdue Pegboard Test with reaching, grasping, transporting, and inserting subtasks. We examined how long and where participants concentrated on these subtasks and, using the findings, introduced a new virtual hand visualization method to increase accuracy. We hope that our results can be used in future virtual reality applications where users have to interact with virtual objects accurately.
Citation Count: 0
Touch to Learn: A Review of Haptic Technology's Impact on Skill Development and Enhancing Learning Abilities for Children
(Wiley, 2024) Hatira, Amal; Sarac, Mine
Early 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