Browsing by Author "Sarac, Mine"

Now showing 1 - 20 of 27

Citation - WoS: 1
Citation - Scopus: 1
Gamifying Haptics User Studies: Comparison of Response Times From Smartphone Interfaces
(IEEE Computer Soc, 2025) Kudsi, Bushra; Xu, Doris; Sen, Umit; Yoshida, Kyle T.; Stroppa, Fabio; Nunez, Cara M.; Sarac, Mine
Haptics user studies are often restricted to a set, physical location and use methods that do not captivate the user. Applying game design elements can create an entertaining environment and increase user engagement. Using ubiquitous tools, like smartphones, to conduct haptics user studies could allow researchers to access larger participant groups while a gamified approach could facilitate the data collection by making the experiment more enjoyable. To explore this concept, this work presents a gamified version of an existing psychophysical experiment that investigates response time to multisensory cues using a smartphone based on "Whac-A-Mole". We conducted a user study to compare our gamified interface with an existing psychophysical interface with thirteen participants exploring the response time from eighteen combinations of auditory, haptic, and visual stimuli at different levels of intensities and participant preferences for both interfaces. The results demonstrate that the gamified interface successfully captured similar trends in response times and significantly elevated participant enjoyment ($p < 0.003$), but did not result in equivalent response times to the original interface. This work shows the benefits and drawbacks of following a gamification approach when designing haptics user studies and discusses factors and trade-offs to consider when gamifying studies.
Citation - WoS: 1
Citation - Scopus: 1
Haptic Relocation Away From the Fingertip: Where, Why, and How
(IEEE Computer Soc, 2025) Sarac, Mine
Tactile haptic devices are often designed to render meaningful, complex, and realistic touch-based information on users' skin. While fingertips and hands are the most preferred body locations to render haptic feedback, recent trends allow such feedback to be extended to alternative body locations (e.g., wrist, arm, torso, foot) for various scenarios due to reasons such as wearability and needs of the application. In this paper, I address the new concept of haptic relocation. It refers to scenarios in which the expected feedback is related to the fingertips but rendered on a different body location instead - e.g., contact forces registered by two robotic fingers during teleoperation rendered to the users' wrist instead of the fingers. I investigated the design choices of wearable haptic devices for haptic relocation concerning different body locations, targeted applications, and actuator selection. I discuss approaches and design choices from the literature by speculating on the possible reasons, and conclude the paper by highlighting some challenges and issues to be mindful of in the future. This paper will guide engineers and researchers in searching for alternative haptic rendering solutions - especially when fingers and hands are not available for haptic interaction.
Citation - WoS: 3
Citation - Scopus: 4
Effect of Hand and Object Visibility in Navigational Tasks Based on Rotational and Translational Movements in Virtual Reality
(Ieee Computer Soc, 2024) Hatira, Amal; 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 - WoS: 3
Citation - Scopus: 4
The Impact of Evolutionary Computation on Robotic Design: a Case Study With an Underactuated Hand Exoskeleton
(Ieee, 2024) Akbas, Baris; Yuksel, Huseyin Taner; Soylemez, Aleyna; Zyada, Mazhar Eid; Sarac, Mine; Stroppa, Fabio
Robotic exoskeletons can enhance human strength and aid people with physical disabilities. However, designing them to ensure safety and optimal performance presents significant challenges. Developing exoskeletons should incorporate specific optimization algorithms to find the best design. This study investigates the potential of Evolutionary Computation (EC) methods in robotic design optimization, with an underactuated hand exoskeleton (U-HEx) used as a case study. We propose improving the performance and usability of the U-HEx design, which was initially optimized using a naive brute-force approach, by integrating EC techniques such as Genetic Algorithm and Big Bang-Big Crunch Algorithm. Comparative analysis revealed that EC methods consistently yield more precise and optimal solutions than brute force in a significantly shorter time. This allowed us to improve the optimization by increasing the number of variables in the design, which was impossible with naive methods. The results show significant improvements in terms of the torque magnitude the device transfers to the user, enhancing its efficiency. These findings underline the importance of performing proper optimization while designing exoskeletons, as well as providing a significant improvement to this specific robotic design.
Citation - WoS: 7
Citation - Scopus: 8
Optimizing soft robot design and tracking with and without evolutionary computation: an intensive survey
(Cambridge Univ Press, 2024) Stroppa, Fabio; 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 - WoS: 5
Citation - Scopus: 9
EyeGuide & EyeConGuide: Gaze-based Visual Guides to Improve 3D Sketching Systems
(Assoc Computing Machinery, 2024) Turkmen, Rumeysa; 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 - WoS: 5
Citation - Scopus: 9
Effects 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 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 - WoS: 9
Citation - Scopus: 9
The Impact of Haptic Feedback During Sudden, Rapid Virtual Interactions
(Ieee, 2023) Tanacar, Nizamettin T.; 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 - WoS: 5
Citation - Scopus: 7
Eye-Hand Coordination Training: a Systematic Comparison of 2d, Vr, and Ar Display Technologies and Task Instructions
(Ieee Computer Soc, 2024) Aliza, Aliza; 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.
Fine Motor Tasks in Virtual Reality: the Impact of Haptic Feedback and Object Characterization
(IEEE-Inst Electrical Electronics Engineers Inc, 2025) Hatira, Nour; Sarac, Mine
Fine motor tasks in Virtual Reality (VR) are often constrained by the lack of natural sensory cues, particularly the sense of touch. Previous studies have shown that object characteristics (e.g., shape and size) influence how users perceive and interact with objects. However, the literature lacks insight into how these factors affect each other. This study investigates how different haptic feedback modalities and object characteristics influence user performance during fine motor tasks in VR. We conducted a user study with 25 participants as SenseGlove Nova 1 rendered alternative haptic feedback conditions: combined (force and vibration), force-only, vibration-only, and no feedback. Participants grasped and inserted virtual objects of different shapes (cube, cylinder, pentagon, triangle) and sizes (small, medium, large) into a toybox. Our results show that combined feedback consistently led to greater precision, fewer collisions, and an improved manipulation experience, particularly with larger and more complex objects. Object characteristics also significantly influenced performance: medium-sized and simpler-shaped objects created the best results. Additionally, object characteristics also influenced performance, with medium-sized and simpler-shaped objects leading to better performance. Our findings indicate the need to choose haptic feedback modalities based on object-specific characteristics for better user performance and experience.
Citation - WoS: 3
Citation - Scopus: 5
Effect 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, 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 - WoS: 26
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 - WoS: 10
Citation - Scopus: 13
Optimizing Exoskeleton Design with Evolutionary Computation: An Intensive Survey
(Mdpi, 2023) Stroppa, Fabio; 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 - WoS: 7
Citation - Scopus: 9
Measuring 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, 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 - WoS: 5
Citation - Scopus: 7
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.
Self-Balancing Tray for Service Robots
(IEEE, 2025) Ozdel, Mustafa Enes; Kilic, Emirhan; Atila, Mustafa; Tavakol, Vahit Baris; Sarac, Mine
One of the biggest challenges in the field of service robots is achieving steady transportation of goods. This challenge can be addressed by developing self-balancing platforms. This study proposes a mechanism that maintains tray steadiness on inclined surfaces and during abrupt movements. The system integrates a dual-servo motor controlled by an inertial measurement unit (IMU) sensor for real-time inclination detection and correction. A linkage mechanism dynamically adjusts the tray's position based on sensor feedback, ensuring optimal balance. Experimental results validate the system's effectiveness in maintaining steadiness under various conditions, enhancing service robot functionality, reducing spillage, and improving reliability.
Enhanced Design of a Hand Exoskeleton: Balancing Force Transmission and Actuation with Evolutionary Algorithms
(IEEE-INST Electrical Electronics Engineers INC, 2025) Akbas, Baris; Yuksel, Huseyin Taner; Soylemez, Aleyna; Sarac, Mine; Stroppa, Fabio
Exoskeletons can boost human strength and provide assistance to individuals with physical disabilities. However, ensuring safety and optimal performance in their design poses substantial challenges. This study addresses significant challenges of ensuring safety and maximizing performance in the design process for an underactuated hand exoskeleton intended for physical rehabilitation. We first implemented a single objective optimization problem by maximizing force transmission from the actuator to the finger joints, then expanded into multi-objective optimization by also minimizing the variance of torques rendered on the finger joints and the actuator displacement needed. The optimization relies on a Genetic Algorithm, the Big Bang-Big Crunch Algorithm, and their versions for multi-objective optimization. Our simulation results and statistical analyses revealed that using Big Bang-Big Crunch provides high and more consistent results in terms of optimality with lower convergence time. In addition, adding more objectives offers a variety of trade-off solutions to the designers, who might later set priorities for the objectives without repeating the process - at the cost of complicating the optimization algorithm and computational burden. These findings underline the critical importance of performing proper optimization techniques while designing exoskeletons, as well as providing a significant improvement to this specific robotic design that could provide more effective rehabilitation therapies and augmented human-robot interactions.
Citation - WoS: 14
Citation - Scopus: 15
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 - WoS: 5
Citation - Scopus: 10
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
Citation - Scopus: 2
Enhancing Eye-Hand Coordination in Volleyball Players: A Comparative Analysis of VR, AR, and 2D Display Technologies and Task Instructions
(IEEE Computer SOC, 2024) Hatira, Nour; Aliza, Aliza; Batmaz, Anil Ufuk; Sarac, Mine
Previous studies analyzed user motor performance with Virtual Reality (VR) and Augmented Reality (AR) Eye-Hand Coordination Training Systems (EHCTSs) while asking participants to follow specific task instructions. Although these studies suggested VR & AR EHCTSs as potential training systems for sports players, they recruited participants for their user studies among general population. In this paper, we examined the training performance of 16 professional volleyball players over 8 days using EHCTSs with three display technologies (VR, AR, and 2D touchscreen) and with four distinct task instructions (prioritizing speed, error rate, accuracy, or none). Our results indicate that volleyball players performed best with 2D touchscreen in terms of time, error rate, accuracy, precision, and throughput. Moreover, their performance was superior when using VR over AR. They also successfully followed the task instructions given to them and consistently improved their throughput performance. These findings underscore the potential of EHCTS in volleyball training and highlight the need for further research to optimize VR & AR user experience and performance.