Victor Adriel de Jesus Oliveira

Localized Magnification in Vibrotactile HMDs for Accurate Spatial Awareness

Actuator density is an important parameter in the design of vibrotactile displays. When it comes to obstacle detection or navigation tasks, a high number of tactors may provide more information, but not necessarily better performance. Depending on the body site and vibration parameters adopted, high density can make it harder to detect tactors in an array. In this paper, we explore the trade-off between actuator density and precision by comparing three kinds of directional cues. After performing a within-subject naive search task using a head-mounted vibrotactile display, we found that increasing the density of the array locally provides higher performance in detecting directional cues.

Designing a Vibrotactile Head-Mounted Display for Spatial Awareness in 3D Spaces

Due to the perceptual characteristics of the head, vibrotactile Head-mounted Displays are built with low actuator density. Therefore, vibrotactile guidance is mostly assessed by pointing towards objects in the azimuthal plane. When it comes to multisensory interaction in 3D environments, it is also important to convey information about objects in the elevation plane. In this paper, we design and assess a haptic guidance technique for 3D environments. First, we explore the modulation of vibration frequency to indicate the position of objects in the elevation plane. Then, we assessed a vibrotactile HMD made to render the position of objects in a 3D space around the subject by varying both stimulus loci and vibration frequency. Results have shown that frequencies modulated with a quadratic growth function allowed a more accurate, precise, and faster target localization in an active head pointing task. The technique presented high usability and a strong learning effect for a haptic search across different scenarios in an immersive VR setup.

Spatial discrimination of vibrotactile stimuli around the head

Several studies evaluated vibrotactile stimuli on the head to aid orientation and communication. However, the acuity for vibration of the heads skin still needs to be explored. In this paper, we report the assessment of the spatial resolution on the head. We performed a 2AFC psychophysical experiment systematically varying the distance between pairs of stimuli in a standard-comparison approach. We took into consideration not only the perceptual thresholds but also the reaction times and subjective factors, like workload and vibration pleasantness. Results show that the region around the forehead is not only the most sensitive, with thresholds under 5mm, but it is also the region wherein the spatial discrimination was felt to be easier to perform. We also have found that it is possible to describe acuity on the head for vibrating stimulus as a function of skin type (hairy or glabrous) and of the distance of the stimulated loci from the head midline.

Assessment of Tactile Languages as Navigation Aid in 3D Environments

In this paper we present the design and evaluate alternative tactile vocabularies to support navigation in 3D environments. We have focused on the tactile communication expressiveness by applying a prefixation approach in the construction of the tactile icons. We conducted user experiments to analyze the effects of both prefixation and the use of tactile sequences on the user’s performance in a navigation task. Results show that, even if tactile sequences are more difficult to process during the navigation task, the prefixed patterns were easier to learn in all assessed vocabularies.

Introducing the Modifier Tactile Pattern for Vibrotactile Communication

We introduce the concept of “Modifier Tactile Pattern” as a pattern that modifies the interpretation of other elements that compose a Tacton or an entire tactile message. This concept was inspired by the prefixation strategies of the Braille system. We also show how to design tactile languages applying the concept of Modifier by following methodologies and approaches of Tacton design that already exist in literature. Then a modifier-based tactile language is designed and assessed in a user study.

Proactive haptic articulation for intercommunication in collaborative virtual environments

In this paper, we look upon elements present in speech articulation to introduce proactive haptic articulation as a novel approach for communication in Collaborative Virtual Environments. We defend the hypothesis that elements present in natural language, when added to the design of the vibrotactile vocabulary, should provide an expressive medium for intercommunication. Moreover, the ability to render tactile cues to a teammate should encourage users to extrapolate a given vocabulary while using it. We implemented a collaborative puzzle task to observe the use of such vocabulary. Results show that participants autonomously adapted it to attend their communication needs during the assembly.

Experiencing guidance in 3D spaces with a vibrotactile head-mounted display

Vibrotactile feedback is broadly used to support different tasks in virtual and augmented reality applications, such as navigation, communication, attentional redirection, or to enhance the sense of presence in virtual environments. Thus, we aim to include the haptic component to the most popular wearable used in VR applications: the VR headset. After studying the acuity around the head for vibrating stimuli, and trying different parameters, actuators, and configurations, we developed a haptic guidance technique to be used in a vibrotactile Head-mounted Display (HMD). Our vi-brotactile HMD was made to render the position of objects in a 3D space around the subject by varying both stimulus loci and vibration frequency. In this demonstration, the participants will interact with different scenarios where the mission is to select a number of predefined objects. However, instead of displaying occlusive graphical information to point to these objects, vibrotactile cues will provide guidance in the VR setup. Participants will see that our haptic guidance technique can be both easy to use and entertaining. (See Video: https://youtu.be/_H0MQy6QD7M).

Poster: Applying tactile languages for 3D navigation

In this paper we present the design and evaluate alternative tactile vocabularies to support navigation in 3D environments. We have focused on the tactile communication expressiveness by applying a prefixation approach in the construction of the tactile icons. We conducted user experiments to analyze the effects of both prefixation and the use of tactile sequences on the users performance in a navigation task. Results show that the group that used the prefixation-based vocabulary performed better.

Anti-Veering Vibrotactile HMD for Assistance of Blind Pedestrians

Veering is a common experience for blind pedestrians and for individuals walking in unfamiliar spaces. In this paper, we assess a vibrotactile Head-Mounted Display to assist blind individuals to walk straight from a point to another. Our goal was to assess such device for both assistance and self-Orientation and Mobility (O&M) training to provide more autonomy to blind pedestrians. Blind and blindfolded subjects performed a series of assisted and non-assisted sessions to verify how deviation errors are modulated according to the use of the device. Moreover, the vibrotactile feedback was compared to audible walking signals commonly present in many road-cross scenarios, as well as in traditional O&M sessions. Performance and subjective measures were assessed as a function of stimulus modality and group profile. Results show that the vibrotactile feedback significantly reduces the veering for both sighted and blind subjects.

Assessing Articulatory Modalities for Intercommunication Using Vibrotactile HMDs

In computer-mediated tactile intercommunication, users not only have to perceive tactile cues but also have to articulate them to carry a two-way interaction. By pressing buttons or performing specific gestures, interlocutors can exchange tactile signals but are not able to extrapolate the given vocabulary. When more access to hardware parameters is provided instead, interlocutors can have more autonomy. Yet, changes in articulation might produce tactile signals that are not perceptually suitable, hindering mutual understanding during intercommunication. In this paper, we explore the trade-off between freedom of articulation and mutual understanding by comparing three articulatory approaches. Dyads performed a collaborative task using their vibrotactile HMDs to communicate. Their performance during the task, as well as mutual understanding, workload and easiness, were assessed as a function of each articulatory condition. Results show that static and mediating conditions support higher performance and mutual understanding compared to a dynamic articulation.