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Haptics: Technology and Applications—2021

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (31 October 2021) | Viewed by 37358
The Deadline for manuscript submissions is 31 October 2021, but we still accept papers in case of new submissions. Related Special Issue: Haptics: Technology and Applications

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Prof. Dr. Sang-Youn Kim

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Director of Advanced Technology Research Center, Korea University of Technology and Education, Cheonan 31253, Republic of Korea
Interests: haptic actuator; soft actuator; soft robot; vibrotactile actuator
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue seeks papers which examine some of the latest advances with respect to haptic actuators, haptic rendering, haptic applications in virtual reality/augmented reality, haptic applications in virtual education/training, and all aspects of haptics, including neuroscience, psychophysics, perception, and interactions. This Special Issue also welcomes papers related to medical and surgical simulations, skills training, rehabilitation robotics, collaborative human–robot interactions, communication, and haptic feedback for design and the arts.

Prof. Dr. Sang-Youn Kim
Guest Editor

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Keywords

haptic/vibrotactile actuator
psychophysics and perception
multimodal interaction
virtual reality
haptic interfaces design
haptic rendering and modeling

Published Papers (14 papers)

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Research

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11 pages, 4279 KiB

Open AccessArticle

Flexible Vibrotactile Actuator Based on Dielectric Elastomer for Smart Handheld Devices

by Yong Hae Heo, Dong-Soo Choi, Do Eun Kim and Sang-Youn Kim

Appl. Sci. 2021, 11(24), 12020; https://doi.org/10.3390/app112412020 - 17 Dec 2021

Cited by 6 | Viewed by 2162

Abstract

This paper presents an electroactive and soft vibrotactile actuator based on a dielectric elastomer. The vibrotactile actuator is composed of an upper layer, an adhesive tape layer, a dielectric layer with bumps, and a lower layer. When a voltage is applied to the actuator, an electrostatic force created between the upper and lower layers pulls the upper layer down, compressing the dielectric layer. As soon as the applied voltage is released, the upper layer is quickly restored to its initial state by the elastic force of the compressed dielectric elastomer. Because two forces contribute to the actuation at the same time, the created vibration is sufficiently strong to stimulate human mechanoreceptors. When the applied voltage is removed, the upper layer and dielectric elastomer return to their initial shapes. We conducted experiments to determine the best weight ratio of polydimethylsiloxane (PDMS) and Ecoflex, and to quantitatively investigate the haptic performance of the proposed vibrotactile actuator. The experiments clearly show that the plasticized vibrotactile actuator can create a variety of haptic sensations over a wide frequency range. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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13 pages, 1254 KiB

Open AccessArticle

The Impact of Stimulation Intensity on Spatial Discrimination with Multi-Pad Finger Electrode

by Jovana Malešević, Milica Isaković, Martin A. Garenfeld, Strahinja Došen and Matija Štrbac

Appl. Sci. 2021, 11(21), 10231; https://doi.org/10.3390/app112110231 - 1 Nov 2021

Cited by 7 | Viewed by 2032

Abstract

Multi-pad electrotactile stimulation can be used to provide tactile feedback in different applications. The electrotactile interface needs to be calibrated before each use, which entails adjusting the intensity to obtain clear sensations while allowing the subjects to differentiate between active pads. The present study investigated how the stimulation intensity affects the localization of sensations using a multi-pad electrode placed on a fingertip and proximal phalange. First, the sensation, localization, smearing and discomfort thresholds were determined in 11 subjects. Then, the same subjects performed a spatial discrimination test across a range of stimulation intensities. The results have shown that all thresholds were significantly different, while there was no difference in the threshold values between the pads and phalanges. Despite the subjective feeling of spreading of sensations, the success rates in spatial discrimination were not significantly different across the tested stimulation intensities. However, the performance was better for distal compared to proximal phalange. Presented results indicate that spatial discrimination is robust to changes in the stimulation intensity. Considering the lack of significant difference in the thresholds between the pads, these results imply that more coarse adjustment of stimulation amplitude (faster calibration) might be enough for practical applications of a multi-pad electrotactile interface. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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18 pages, 590 KiB

Open AccessArticle

Improving the Discriminability of Haptic Icons: The Haptic Tuning Fork

by Laura Raya, Sara A. Boga, Marcos Garcia-Lorenzo and Sofia Bayona

Appl. Sci. 2021, 11(18), 8772; https://doi.org/10.3390/app11188772 - 21 Sep 2021

Viewed by 1857

Abstract

Technological advances enable the capture and management of complex data sets that need to be correctly understood. Visualisation techniques can help in complex data analysis and exploration, but sometimes the visual channel is not enough, or it is not always available. Some authors propose using the haptic channel to reinforce or substitute the visual sense, but the limited human haptic short-term memory still poses a challenge. We present the haptic tuning fork, a reference signal displayed before the haptic information for increasing the discriminability of haptic icons. With this reference, the user does not depend only on short-term memory. We have decided to evaluate the usefulness of the haptic tuning fork in impedance kinesthetic devices as these are the most common. Furthermore, since the renderable signal ranges are device-dependent, we introduce a methodology to select a discriminable set of signals called the haptic scale. Both the haptic tuning fork and the haptic scale proved their usefulness in the performed experiments regarding haptic stimuli varying in frequency. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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17 pages, 4771 KiB

Open AccessFeature PaperArticle

Design and Experimental Evaluation of an Electrorheological Haptic Module with Embedded Sensing

by Alex Mazursky, Jeong-Hoi Koo, Taylor Mason, Sam-Yong Woo and Tae-Heon Yang

Appl. Sci. 2021, 11(16), 7723; https://doi.org/10.3390/app11167723 - 22 Aug 2021

Cited by 3 | Viewed by 2606

Abstract

We present a miniature haptic module based on electrorheological fluid, designed for conveying combined stiffness and vibrotactile sensations at a small scale. Haptic feedback is produced through electrorheological fluid’s controllable resistive force and varies with the actuator’s deformation. To demonstrate the proposed actuator’s feedback in realistic applications, a method for measuring the actuator’s deformation must be implemented for active control. To this end, in this study, we incorporate a sensor design based on a bend-sensitive resistive film to the ER haptic actuator. The combined actuator and sensor module was tested for its ability to simultaneously actuate and sense the actuator’s state under indentation. The results show that the bend sensor can accurately track the actuator’s displacement over its stroke. Thus, the proposed sensor may enable control of the output resistive force according to displacement, which may lead to more informed and engaging combined kinesthetic and tactile feedback. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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13 pages, 3823 KiB

Open AccessArticle

A Feasibility Study of a Vibrotactile System Based on Electrostatic Actuators for Touch Bar Interfaces: Experimental Evaluations

by Taylor Mason, Jeong-Hoi Koo, Jae-Ik Kim, Young-Min Kim and Tae-Heon Yang

Appl. Sci. 2021, 11(15), 7084; https://doi.org/10.3390/app11157084 - 31 Jul 2021

Cited by 3 | Viewed by 1442

Abstract

Vibrotactile feedback is a very desirable feature for many touchscreen applications, creating a more engaging and effective user experience. Although it is common in small electronic devices, this feedback is often absent in large touchscreen devices because it is difficult to provide vibration sensations and control the magnitude throughout the display. Because of their long shape (over 20 cm), touch bar displays are susceptible to the same challenges that other large display types face. Thus, there is a need for a vibrotactile actuation system capable of generating a freely positionable and fully controllable point of stimulation with satisfying force output at any point of a touch bar display. This study proposes a new spring boundary condition vibrotactile system as a way to provide such feedback in touch bar interfaces. A prototype system was created using two electrostatic resonant actuators and a thin, narrow aluminum beam to study the effect of different actuator excitation parameters on the beam’s response. By varying the number of actuators excited, magnitude, excitation frequency, and signal duration, a minimum vibration of 24.5 m/s² could be created in the beam, with the majority of the beam able to exceed 40 m/s². These results show that a targeted vibrotactile response at a given location in the beam can be achieved and sustained. This demonstrates a promising potential for generating a freely positionable and fully controllable point of vibrotactile stimulation at any point of a touch bar display. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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14 pages, 2023 KiB

Open AccessArticle

Wearable Haptic Device for Stiffness Rendering of Virtual Objects in Augmented Reality

by Yongseok Lee, Somang Lee and Dongjun Lee

Appl. Sci. 2021, 11(15), 6932; https://doi.org/10.3390/app11156932 - 28 Jul 2021

Cited by 12 | Viewed by 4490

Abstract

We propose a novel wearable haptic device that can provide kinesthetic haptic feedback for stiffness rendering of virtual objects in augmented reality (AR). Rendering stiffness of objects using haptic feedback is crucial for realistic finger-based object manipulation, yet challenging particularly in AR due to the co-presence of a real hand, haptic device, and rendered AR objects in the scenes. By adopting passive actuation with a tendon-based transmission mechanism, the proposed haptic device can generate kinesthetic feedback strong enough for immersive manipulation and prevention of inter-penetration in a small-form-factor, while maximizing the wearability and minimizing the occlusion in AR usage. A selective locking module is adopted in the device to allow for the rendering of the elasticity of objects. We perform an experimental study of two-finger grasping to verify the efficacy of the proposed haptic device for finger-based manipulation in AR. We also quantitatively compare/articulate the effects of different types of feedbacks across haptic and visual sense (i.e., kinesthetic haptic feedback, vibrotactile haptic feedback, and visuo-haptic feedback) for stiffness rendering of virtual objects in AR for the first time. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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12 pages, 3406 KiB

Open AccessArticle

Elastic Simulation of Joints with Particle-Based Fluid

by Su-Kyung Sung, Sang-Won Han and Byeong-Seok Shin

Appl. Sci. 2021, 11(15), 6900; https://doi.org/10.3390/app11156900 - 27 Jul 2021

Viewed by 1306

Abstract

Skinning, which is used in skeletal simulations to express the human body, has been weighted between bones to enable muscle-like motions. Weighting is not a form of calculating the pressure and density of muscle fibers in the human body. Therefore, it is not possible to express physical changes when external forces are applied. To express a similar behavior, an animator arbitrarily customizes the weight values. In this study, we apply the kernel and pressure-dependent density variations used in particle-based fluid simulations to skinning simulations. As a result, surface tension and elasticity between particles are applied to muscles, indicating realistic human motion. We also propose a tension yield condition that reflects Tresca’s yield condition, which can be easily approximated using the difference between the maximum and minimum values of the principal stress to simulate the tension limit of the muscle fiber. The density received by particles in the kernel is assumed to be the principal stress. The difference is calculated by approximating the moment of greatest force to the maximum principal stress and the moment of least force to the minimum principal stress. When the density of a particle increases beyond the yield condition, the object is no longer subjected to force. As a result, one can express realistic muscles. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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19 pages, 1203 KiB

Open AccessArticle

User Experience in VR Fashion Product Shopping: Focusing on Tangible Interactions

by Jongsun Kim and Jisoo Ha

Appl. Sci. 2021, 11(13), 6170; https://doi.org/10.3390/app11136170 - 2 Jul 2021

Cited by 6 | Viewed by 3911

Abstract

It is necessary to focus on a VR environment centered on a tangible interaction (TI), which provides and interacts with the user experience (UX) with various sensational forms. Therefore, this study attempted to present UX evaluation items for VR fashion product shopping environment through focusing on the TI. In addition, the developed factors were evaluated for validity through empirical experiments and attempted to explore the possibility of using a VR shopping UX evaluation methodology. As a result of factor analysis of items related to VR shopping, six factors were extracted, and each factor was named as intention to use, playfulness, sharpness, telepresence, interactivity, and usability, respectively. As a result of a t-test for the difference in UX between immersive VR and non-immersive VR, it was found that there were significant differences in intention to use, playfulness, sharpness, and telepresence. As a result of performing a multiple regression analysis to analyze the effect of TI on the VR fashion shopping UX, it was found that interaction, playfulness, and telepresence are UX factors that are formed under the influence of TI in an immersive VR. In addition, intention to use, sharpness, telepresence, and usability were found to be factors experienced as an effect of TI in a non-immersive VR. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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12 pages, 3486 KiB

Open AccessArticle

Free and Forced Vibration Modes of the Human Fingertip

by Gokhan Serhat and Katherine J. Kuchenbecker

Appl. Sci. 2021, 11(12), 5709; https://doi.org/10.3390/app11125709 - 20 Jun 2021

Cited by 10 | Viewed by 2616

Abstract

Computational analysis of free and forced vibration responses provides crucial information on the dynamic characteristics of deformable bodies. Although such numerical techniques are prevalently used in many disciplines, they have been underutilized in the quest to understand the form and function of human fingers. We addressed this opportunity by building DigiTip, a detailed three-dimensional finite element model of a representative human fingertip that is based on prior anatomical and biomechanical studies. Using the developed model, we first performed modal analyses to determine the free vibration modes with associated frequencies up to about 250 Hz, the frequency at which humans are most sensitive to vibratory stimuli on the fingertip. The modal analysis results reveal that this typical human fingertip exhibits seven characteristic vibration patterns in the considered frequency range. Subsequently, we applied distributed harmonic forces at the fingerprint centroid in three principal directions to predict forced vibration responses through frequency-response analyses; these simulations demonstrate that certain vibration modes are excited significantly more efficiently than the others under the investigated conditions. The results illuminate the dynamic behavior of the human fingertip in haptic interactions involving oscillating stimuli, such as textures and vibratory alerts, and they show how the modal information can predict the forced vibration responses of the soft tissue. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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23 pages, 14359 KiB

Open AccessArticle

Research on Contactless Bio-Signal Measurement Technology for Improving Social Awareness of Individuals with Communication Challenges

by Seonghyeon Nam, Hayoung Song and Youngwon Kim

Appl. Sci. 2021, 11(11), 5169; https://doi.org/10.3390/app11115169 - 2 Jun 2021

Viewed by 2177

Abstract

Youth and adults with autism spectrum disorder have poor skills such as communication, qualitative interaction, and emotional expression resulting in low social awareness. In this paper, we propose and explore a contactless bio-signal measurement and functional contents for improving social awareness of individuals with communication challenges. We implemented four individual methods for collecting and analyzing the bio data of the individuals without requiring their attention: (1) heart rate, (2) respiration, (3) facial expression, and (4) interaction. The four techniques are all based on image data received and analyzed from a normal web camera. The data were analyzed in a real-time, fully functional algorithm: implementing the algorithm on a mobile device will require future work. However, we have evaluated our method by developing a functional content including the four methods. Based on the analysis of the collected data from the content and qualitative responses from the field, the contactless bio-signal measurement technology combined with friendly designed user interfaces for the individuals with communication challenges could train them to improve their social awareness. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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12 pages, 2465 KiB

Open AccessArticle

Coupled D33 Mode-Based High Performing Bio-Inspired Piezoelectric MEMS Directional Microphone

by Ashiqur Rahaman, Haeil Jung and Byungki Kim

Appl. Sci. 2021, 11(3), 1305; https://doi.org/10.3390/app11031305 - 1 Feb 2021

Cited by 9 | Viewed by 3153

Abstract

Microelectromechanical system (MEMS) directional microphones have been identified as having use in multi-projected virtual reality applications such as virtual meetings for projecting cameras. In these applications, the acoustic sensitivity plays a vital role as it biases the directional sensing, signal-to-noise ratio (SNR) and self-noise. The acoustic sensitivity is the multiplied outcome of the mechanical sensitivity and the electrical sensitivity. As the dimensions are limited in MEMS technology, the improvement of the acoustic sensitivity by reflecting the mechanical as well as electrical domains is a challenge. This paper reports on a new formation of the D33 mode, the coupled D33 mode, based on piezoelectric sensing to improve the acoustic functionalities. The unique advancement of the proposed D33 mode is that it allows multiple spans of the regular D33 mode to perform together, despite this increasing the diaphragm’s dimensions. At a reduced diaphragm size, the orientation of the coupled D33 mode realizes the maximum conversion of the mechanical deflection into electrical sensitivity. The significance of the proposed D33 mode in comparison to the regular D33 mode is simulated using COMSOL Multiphysics. Then, for a proof–of–concept, the experimental validation is carried out using a piezoelectric MEMS directional microphone inspired by the ears of the fly Ormia ochracea. In both ways, the results are found to be substantially improved in comparison with the regular approach of the D33 mode, showing the novelty of this work. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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9 pages, 736 KiB

Open AccessArticle

Influence of Haptic Sensory Input through Different Kinds of Clothing on Gait Performance

by Kazushige Oshita and Sumio Yano

Appl. Sci. 2020, 10(21), 7590; https://doi.org/10.3390/app10217590 - 28 Oct 2020

Cited by 2 | Viewed by 1796

Abstract

This study investigated the effects of haptic sensory input by different types of clothing worn on gait performance. Twelve healthy men performed normal and tandem gait tests with blindfolds under three different clothing conditions: (1) wearing only half tights (HT); (2) wearing a skirt-like draped outfit such as a cotton cloth wrapped around the waist and extended to the lower leg (DC); and (3) wearing a trouser-like outfit such as tracksuit bottoms (TS). Although gait speed was significantly increased in DC as compared with HT, this was not observed in TS. Missteps during tandem gait were significantly reduced with DC. In addition, DC made walking easier for individuals as compared with TS. These findings suggest that wearing a skirt-like outfit such as kilts in Scotland or the hakama in Japan may provide haptic sensory cues to enhance individuals’ perceptions of their body orientation as compared with trouser-like clothing that is in continuous contact with the legs. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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23 pages, 1329 KiB

Open AccessArticle

Visuo-Haptic Simulations to Understand the Dependence of Electric Forces on Distance

by Luis Neri, Víctor Robledo-Rella, Rosa María Guadalupe García-Castelán, Andres Gonzalez-Nucamendi, David Escobar-Castillejos and Julieta Noguez

Appl. Sci. 2020, 10(20), 7190; https://doi.org/10.3390/app10207190 - 15 Oct 2020

Cited by 4 | Viewed by 1635

Abstract

In this paper, the potential of visuo-haptic simulators to help engineering students to understand the nature of electric forces between different electric charge distributions is addressed. Three visuo-haptic simulators were designed to perceive the attractive–repulsive behavior as well as the dependence on distance of electrical forces for: (a) point charge, (b) line charge, and (c) plane charge. Design elements were incorporated to improve the 3D perception of the simulators. A sample of N = 111 engineering students practiced with the simulators: 87 enrolled in an Electricity and Magnetism course and 24 enrolled in a more advanced Electromagnetic Fields course. Pre-test and Post-test were applied before and after working with the simulators and average learning gains were obtained. t-tests were performed to determine the statistical significance of the results. Significant learning gains were obtained for the comprehension of the force dependence in the case of line charge and plane charge, but not for the point charge, due to the fact that most students started with very high Pre-test scores in this last case. These results suggest that the use of visuo-haptic simulators may help students to better identify the dependence of electric forces on distance. It was also observed that the potential effect of improving the recognition of electric interactions was higher among students with lower previous familiarity with these topics, as compared to more advanced students. Through exit surveys, it was found that the students liked very much the haptic activity and that it sparked their interest in learning new physical concepts. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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Review

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29 pages, 564 KiB

Open AccessFeature PaperReview

Designing Pedagogically Effective Haptic Systems for Learning: A Review

by Riley Crandall and Ernur Karadoğan

Appl. Sci. 2021, 11(14), 6245; https://doi.org/10.3390/app11146245 - 6 Jul 2021

Cited by 12 | Viewed by 3516

Abstract

Haptic technology enables users to utilize their sense of touch while engaging with a virtual representation of objects in a simulated environment. It is a bidirectional technology in that it facilitates the interaction between the user and these virtual representations by allowing them to apply force onto one another, which is analogous to our real-world interactions with physical objects as action-reaction pairs. The sense of touch is a powerful and innate learning tool that we readily employ starting from very early ages as infants even before learning to walk. Therefore, it is natural that incorporating haptic technology into pedagogical methods has been an active research area as it has significant potential to enrich the learning experience and provide an engaging environment for learners. In this paper, we reviewed studies from various disciplines that incorporate haptics to increase the quality of teaching and learning while emphasizing the underlying cognitive theories. In that direction, we describe two of the most common cognitive theories, the Cognitive Load and Embodied Cognition theories, that developers use to support haptic technology’s implications and use in learning environments. We then explore the effects of haptic design on its current applicability following these two theories. Finally, we summarize the best design practices to develop haptic simulations for learning, address gaps in current research, and propose new research directions. Full article

(This article belongs to the Special Issue Haptics: Technology and Applications—2021)

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