Haptic Discrimination and Matching of Viscosity

In three experiments, viscosity perception of liquids using the sense of touch was studied. The first two were discrimination experiments in which Weber fractions were determined for a number of viscosities spanning the range of what is encountered in daily life, and for two ways of perceiving viscosity (stirring with a spatula or with the index finger). For high viscosities, Weber fractions were around 0.3, whereas they increased for lower viscosities. For low viscosities, discrimination performance was much worse with the finger than with the spatula. In the third experiment, subjects matched liquids perceived with these two methods, which resulted in biases of around 80 %. Control experiments and force measurements were performed to find an explanation for these results. It was concluded that the relationship between perceived and physical viscosity is steeper for stirring liquids with a spatula than stirring with the finger

Multimodal perception of histological images for persons blind or visually impaired

Currently there is no suitable substitute technology to enable blind or visually impaired (BVI) people to interpret visual scientific data commonly generated during lab experimentation in real time, such as performing light microscopy, spectrometry, and observing chemical reactions. This reliance upon visual interpretation of scientific data certainly impedes students and scientists that are BVI from advancing in careers in medicine, biology, chemistry, and other scientific fields. To address this challenge, a real-time multimodal image perception system is developed to transform standard laboratory blood smear images for persons with BVI to perceive, employing a combination of auditory, haptic, and vibrotactile feedbacks. These sensory feedbacks are used to convey visual information through alternative perceptual channels, thus creating a palette of multimodal, sensorial information. A Bayesian network is developed to characterize images through two groups of features of interest: primary and peripheral features. Causal relation links were established between these two groups of features. Then, a method was conceived for optimal matching between primary features and sensory modalities. Experimental results confirmed this real-time approach of higher accuracy in recognizing and analyzing objects within images compared to tactile images

Haptics Rendering and Applications

There has been significant progress in haptic technologies but the incorporation of haptics into virtual environments is still in its infancy. A wide range of the new society's human activities including communication, education, art, entertainment, commerce and science would forever change if we learned how to capture, manipulate and reproduce haptic sensory stimuli that are nearly indistinguishable from reality. For the field to move forward, many commercial and technological barriers need to be overcome. By rendering how objects feel through haptic technology, we communicate information that might reflect a desire to speak a physically- based language that has never been explored before. Due to constant improvement in haptics technology and increasing levels of research into and development of haptics-related algorithms, protocols and devices, there is a belief that haptics technology has a promising future

FingerSlide: Investigating Passive Haptic Sliding As A Tacton Channel

The haptic sensation of sliding a surface under a probing finger can be used to convey surface information or coded data to the user. In this paper, we investigate users' ability to discern different sliding profiles based on the velocity and direction of sliding for use as haptic-tactons. We built FingerSlide, a novel haptic device which can position and control moving surfaces under a user's finger and used this to run two independent studies. The first study investigates if users can identify the direction of sliding at different velocities. The second study investigates if the users can distinguish a difference between two velocities. Our results show a faster response for higher velocities in the direction study and high error rates in identifying differences in the direction study. We discuss these results and infer design considerations for haptic devices that use the sliding effect to convey information

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Haptic perception

Fueled by novel applications, interest in haptic perception is growing. This paper provides an overview of the state of the art of a number of important aspects of haptic perception. By means of touch we can not only perceive quite different material properties, such as roughness, compliance, friction, coldness and slipperiness, but we can also perceive spatial properties, such as shape, curvature, size and orientation. Moreover, the number of objects we have in our hand can be determined, either by counting or subitizing. All these aspects will be presented and discussed in this paper. Although our intuition tells us that touch provides us with veridical information about our environment, the existence of prominent haptic illusions will show otherwise. Knowledge about haptic perception is interesting from a fundamental viewpoint, but it also is of eminent importance in the technological development of haptic devices. At the end of this paper, a few recent applications will be presented

Effects of Dual-Frequency Environment Exploration on Stiffness Discrimination Thresholds

Previously, excitation frequency has been found to alter perceptual discrimination thresholds of stiffness, mass, and damping. Here, we explore how the blending of two frequencies could affect the just noticeable difference for stiffness. In a perceptual experiment based on the method of adjustments, we tested participants’ ability to match a reference stiffness moving at combinations of two frequencies to explore the effects on stiffness discrimination. As more of the lower frequency was added, participants’ ability to accurately match the reference was hampered. Results suggest that as two frequencies are excited, the resulting perceptual thresholds are blended between the levels for the individual frequencies

Tactual perception: a review of experimental variables and procedures

This paper reviews literature on tactual perception. Throughout this review we will highlight some of the most relevant variables in touch literature: interaction between touch and other senses; type of stimuli, from abstract stimuli such as vibrations, to two- and three-dimensional stimuli, also considering concrete stimuli such as the relation between familiar and unfamiliar stimuli or the haptic perception of faces; type of participants, separating studies with blind participants, studies with children and adults, and an analysis of sex differences in performance; and finally, type of tactile exploration, considering conditions of active and passive touch, the relevance of movement in touch and the relation between exploration and time. This review intends to present an organised overview of the main variables in touch experiments, attending to the main findings described in literature, to guide the design of future works on tactual perception and memory.This work was funded by the Portuguese “Foundation for Science and Technology” through PhD scholarship SFRH/BD/35918/2007

Tactile-STAR: A Novel Tactile STimulator And Recorder System for Evaluating and Improving Tactile Perception

Many neurological diseases impair the motor and somatosensory systems. While several different technologies are used in clinical practice to assess and improve motor functions, somatosensation is evaluated subjectively with qualitative clinical scales. Treatment of somatosensory deficits has received limited attention. To bridge the gap between the assessment and training of motor vs. somatosensory abilities, we designed, developed, and tested a novel, low-cost, two-component (bimanual) mechatronic system targeting tactile somatosensation: the Tactile-STAR—a tactile stimulator and recorder. The stimulator is an actuated pantograph structure driven by two servomotors, with an end-effector covered by a rubber material that can apply two different types of skin stimulation: brush and stretch. The stimulator has a modular design, and can be used to test the tactile perception in different parts of the body such as the hand, arm, leg, big toe, etc. The recorder is a passive pantograph that can measure hand motion using two potentiometers. The recorder can serve multiple purposes: participants can move its handle to match the direction and amplitude of the tactile stimulator, or they can use it as a master manipulator to control the tactile stimulator as a slave. Our ultimate goal is to assess and affect tactile acuity and somatosensory deficits. To demonstrate the feasibility of our novel system, we tested the Tactile-STAR with 16 healthy individuals and with three stroke survivors using the skin-brush stimulation. We verified that the system enables the mapping of tactile perception on the hand in both populations. We also tested the extent to which 30 min of training in healthy individuals led to an improvement of tactile perception. The results provide a first demonstration of the ability of this new system to characterize tactile perception in healthy individuals, as well as a quantification of the magnitude and pattern of tactile impairment in a small cohort of stroke survivors. The finding that short-term training with Tactile-STARcan improve the acuity of tactile perception in healthy individuals suggests that Tactile-STAR may have utility as a therapeutic intervention for somatosensory deficits