An investigation of skin tribology phenomena involved in tactile communication through braille and its associated psychophysical response during task-based discrimination

Most individuals utilize all five senses, especially their sense of sight, to create a unique sensory experience depicting the surrounding environment. Unfortunately, individuals in the blind and visually impaired (BVI) community lack the sense of sight and rely primarily on tactile means to acquire valuable or potentially vital information, leading to the advent of tactile communication methods like braille. A key challenge in controlling the haptic experience of a surface is the lack of fundamental understanding of how various surface attributes, such as friction and texture, affect the tactile response. Oftentimes, braille users experience tactile confusion when scanning complex tactual codes such as tactile graphics or advanced mathematics commonly seen in the STEM fields, but coding standards and limitations in perceptive resolution reduce the opportunity for innovating or redesigning the language to aid the reader. This dissertation aims to address confusion in tactile information transfer by identifying, characterizing, and developing an understanding of the skin-surface contact interactions experienced during braille reading in order to promote innovations in surface engineering and material design that can improve existing tactile communication methods. The authors first propose a method to directly observe an individual’s cognitive response to tactile experiences through an “oddball paradigm” discrimination task using event-related potential (ERP) via electroencephalography (EEG), a technique that is common in visual and auditory psychological sensory studies. Results indicate that varying levels of friction and roughness from textured samples (i.e. sandpaper) elicit different magnitudes of cognitive activity, suggesting that this technique may prove to be a valuable tool in identifying and understanding the root causes of tactile confusion. The second aspect of the research seeks to characterize the fundamental frictional forces that occur during braille reading by investigating the loading interactions as the fingerpad slides over a single braille dot and then progressively increasing the complexity of the topographies (i.e. dot spacing, orientation, count). Derived from Greenwood and Tabor, the authors develop and propose a multi-term friction model that predicts the adhesion and deformation frictional effects of a single feature during skin-on-dot sliding, identifying deformation as the dominant friction mechanism when a soft body slides over a spherical geometry. Incorporating both computational modeling and large-scale tribological tests under displacement-controlled sliding further decomposes the frictional loading mechanisms showing that surface tension and compression are driven by the elastic material’s Poisson effect dependent on the bulk’s position with respect to the dot feature. Here, loads in the vertical direction are governed by bulk material deformation due to contact pressure and loads in the lateral direction are governed by bulk material deformation due to both contact pressure and frictional shear

Do we enjoy what we sense and perceive?:A dissociation between aesthetic appreciation and basic perception of environmental objects or events

This integrative review rearticulates the notion of human aesthetics by critically appraising the conventional definitions, offerring a new, more comprehensive definition, and identifying the fundamental components associated with it. It intends to advance holistic understanding of the notion by differentiating aesthetic perception from basic perceptual recognition, and by characterizing these concepts from the perspective of information processing in both visual and nonvisual modalities. To this end, we analyze the dissociative nature of information processing in the brain, introducing a novel local-global integrative model that differentiates aesthetic processing from basic perceptual processing. This model builds on the current state of the art in visual aesthetics as well as newer propositions about nonvisual aesthetics. This model comprises two analytic channels: aesthetics-only channel and perception-to-aesthetics channel. The aesthetics-only channel primarily involves restricted local processing for quality or richness (e.g., attractiveness, beauty/prettiness, elegance, sublimeness, catchiness, hedonic value) analysis, whereas the perception-to-aesthetics channel involves global/extended local processing for basic feature analysis, followed by restricted local processing for quality or richness analysis. We contend that aesthetic processing operates independently of basic perceptual processing, but not independently of cognitive processing. We further conjecture that there might be a common faculty, labeled as aesthetic cognition faculty, in the human brain for all sensory aesthetics albeit other parts of the brain can also be activated because of basic sensory processing prior to aesthetic processing, particularly during the operation of the second channel. This generalized model can account not only for simple and pure aesthetic experiences but for partial and complex aesthetic experiences as well.</p

Designing Tactile Interfaces for Abstract Interpersonal Communication, Pedestrian Navigation and Motorcyclists Navigation

The tactile medium of communication with users is appropriate for displaying information in situations where auditory and visual mediums are saturated. There are situations where a subject's ability to receive information through either of these channels is severely restricted by the environment they are in or through any physical impairments that the subject may have. In this project, we have focused on two groups of users who need sustained visual and auditory focus in their task: Soldiers on the battle field and motorcyclists. Soldiers on the battle field use their visual and auditory capabilities to maintain awareness of their environment to guard themselves from enemy assault. One of the major challenges to coordination in a hazardous environment is maintaining communication between team members while mitigating cognitive load. Compromise in communication between team members may result in mistakes that can adversely affect the outcome of a mission. We have built two vibrotactile displays, Tactor I and Tactor II, each with nine actuators arranged in a three-by-three matrix with differing contact areas that can represent a total of 511 shapes. We used two dimensions of tactile medium, shapes and waveforms, to represent verb phrases and evaluated ability of users to perceive verb phrases the tactile code. We evaluated the effectiveness of communicating verb phrases while the users were performing two tasks simultaneously. The results showed that performing additional visual task did not affect the accuracy or the time taken to perceive tactile codes. Another challenge in coordinating Soldiers on a battle field is navigating them to respective assembly areas. We have developed HaptiGo, a lightweight haptic vest that provides pedestrians both navigational intelligence and obstacle detection capabilities. HaptiGo consists of optimally-placed vibro-tactile sensors that utilize natural and small form factor interaction cues, thus emulating the sensation of being passively guided towards the intended direction. We evaluated HaptiGo and found that it was able to successfully navigate users with timely alerts of incoming obstacles without increasing cognitive load, thereby increasing their environmental awareness. Additionally, we show that users are able to respond to directional information without training. The needs of motorcyclists are di erent from those of Soldiers. Motorcyclists' need to maintain visual and auditory situational awareness at all times is crucial since they are highly exposed on the road. Route guidance systems, such as the Garmin, have been well tested on automobilists, but remain much less safe for use by motorcyclists. Audio/visual routing systems decrease motorcyclists' situational awareness and vehicle control, and thus increase the chances of an accident. To enable motorcyclists to take advantage of route guidance while maintaining situational awareness, we created HaptiMoto, a wearable haptic route guidance system. HaptiMoto uses tactile signals to encode the distance and direction of approaching turns, thus avoiding interference with audio/visual awareness. Evaluations show that HaptiMoto is intuitive for motorcyclists, and a safer alternative to existing solutions

Wearable Vibrotactile Haptic Device for Stiffness Discrimination during Virtual Interactions

In this paper, we discuss the development of cost effective, wireless, and wearable vibrotactile haptic device for stiffness perception during an interaction with virtual objects. Our experimental setup consists of haptic device with five vibrotactile actuators, virtual reality environment tailored in Unity 3D integrating the Oculus Rift Head Mounted Display (HMD) and the Leap Motion controller. The virtual environment is able to capture touch inputs from users. Interaction forces are then rendered at 500 Hz and fed back to the wearable setup stimulating fingertips with ERM vibrotactile actuators. Amplitude and frequency of vibrations are modulated proportionally to the interaction force to simulate the stiffness of a virtual object. A quantitative and qualitative study is done to compare the discrimination of stiffness on virtual linear spring in three sensory modalities: visual only feedback, tactile only feedback, and their combination. A common psychophysics method called the Two Alternative Forced Choice (2AFC) approach is used for quantitative analysis using Just Noticeable Difference (JND) and Weber Fractions (WF). According to the psychometric experiment result, average Weber fraction values of 0.39 for visual only feedback was improved to 0.25 by adding the tactile feedback