Haptic perception of virtual roughness

The texture of a virtual surface can both increase the sense of realism of an object as well as convey information about object identity, type, location, function, and so on. It is crucial therefore that interface designers know the range of textural information available through the haptic modality in virtual environments. The current study involves participants making roughness judgments on pairs of haptic textures experienced through a force-feedback device. The effect of texture frequency on roughness perception is analysed. The potential range and resolution of textural information available through force-feedback interaction are discussed

Roughness and spatial density judgments on visual and haptic textures using virtual reality

The purpose of this study is to investigate multimodal visual-haptic texture perception for which we used virtual reality techniques. Participants judged a broad range of textures according to their roughness and their spatial density under visual, haptic and visual-haptic exploration conditions. Participants were well able to differentiate between the different textures both by using the roughness and the spatial density judgment. When provided with visualhaptic textures, subjects performance increased (for both judgments) indicating sensory combination of visual and haptic texture information. Most interestingly, performance for density and roughness judgments did not differ significantly, indicating that these estimates are highly correlated. This may be due to the fact that our textures were generated in virtual reality using a haptic pointforce display (PHANToM). In conclusion, it seems that the roughness and spatial density estimate were based on the same physical parameters given the display technology used

A first investigation into the effectiveness of Tactons

This paper reports two experiments relating to the design of Tactons (or tactile icons). The first experiment investigated perception of vibro-tactile "roughness" (created using amplitude modulated sinusoids), and the results indicated that roughness could be used as a parameter for constructing Tactons. The second experiment is the first full evaluation of Tactons, and uses three values of roughness identified in the first experiment, along with three rhythms to create a set of Tactons. The results of this experiment showed that Tactons could be a successful means of communicating information in user interfaces, with an overall recognition rate of 71%, and recognition rates of 93% for rhythm and 80% for roughness

Quantifying perception of nonlinear elastic tissue models using multidimensional scaling

Simplified soft tissue models used in surgical simulations cannot perfectly reproduce all material behaviors. In particular, many tissues exhibit the Poynting effect, which results in normal forces during shearing of tissue and is only observed in nonlinear elastic material models. In order to investigate and quantify the role of the Poynting effect on material discrimination, we performed a multidimensional scaling (MDS) study. Participants were presented with several pairs of shear and normal forces generated by a haptic device during interaction with virtual soft objects. Participants were asked to rate the similarity between the forces felt. The selection of the material parameters – and thus the magnitude of the shear\ud and normal forces – was based on a pre-study prior to the MDS experiment. It was observed that for nonlinear elastic tissue models exhibiting the Poynting effect, MDS analysis indicated that both shear and normal forces affect user perception

Haptic Experience and the Design of Drawing Interfaces

Haptic feedback has the potential to enhance users’ sense of being engaged and creative in their artwork. Current work on providing haptic feedback in computer-based drawing applications has focused mainly on the realism of the haptic sensation rather than the users’ experience of that sensation in the context of their creative work. We present a study that focuses on user experience of three haptic drawing interfaces. These interfaces were based on two different haptic metaphors, one of which mimicked familiar drawing tools (such as pen, pencil or crayon on smooth or rough paper) and the other of which drew on abstract descriptors of haptic experience (roughness, stickiness, scratchiness and smoothness). It was found that users valued having control over the haptic sensation; that each metaphor was preferred by approximately half of the participants; and that the real world metaphor interface was considered more helpful than the abstract one, whereas the abstract interface was considered to better support creativity. This suggests that future interfaces for artistic work should have user-modifiable interaction styles for controlling the haptic sensation

An Investigation of the Interrelationship between Physical Stiffness and Perceived Roughness

Research in the area of haptics and how we perceive the sensations that come from haptic interaction started almost a century ago, yet there is little fundamental knowledge as to how and whether a change in the physical values of one characteristic can alter the perception of another. The increasing availability of haptic interaction through the development of force-feedback devices opened new possibilities in interaction. It allowed for accurate real time change of physical attributes on virtual objects in order to test the haptic perception changes to the human user. An experiment was carried out to ascertain whether a change in the stiffness value would have a noticeable effect on the perceived roughness of a virtual object. Participants were presented with a textured surface and were asked to estimate how rough it felt compared to a standard. What the participants did not know was that the simulated texture on both surfaces remained constant and the only physical attribute changing in every trial was the comparison object’s surface stiffness. The results showed that there is a strong relationship between physical stiffness and perceived roughness that can be accurately described by a power function. Furthermore, the roughness magnitude estimations showed an increase with increasing stiffness values. The conclusion is that there are relationships between these parameters, but that further work is required to validate those relationships

To “Sketch-a-Scratch”

A surface can be harsh and raspy, or smooth and silky, and everything in between. We are used to sense these features with our fingertips as well as with our eyes and ears: the exploration of a surface is a multisensory experience. Tools, too, are often employed in the interaction with surfaces, since they augment our manipulation capabilities. “Sketch-a-Scratch” is a tool for the multisensory exploration and sketching of surface textures. The user’s actions drive a physical sound model of real materials’ response to interactions such as scraping, rubbing or rolling. Moreover, different input signals can be converted into 2D visual surface profiles, thus enabling to experience them visually, aurally and haptically

Assessing haptic properties for data representation

This paper describes the results of a series of forced choice design experiments investigating the discrimination of material properties using a PHANToM haptic device. Research has shown that the PHANToM is effective at displaying graphical information to blind people, but the techniques used so far have been very simple. Our experiments showed that subjects' discrimination of friction was significantly better than that of stiffness or the spatial period of sinusoidal textures, over the range of stimuli investigated. Thus, it is proposed that graphical data could be made more easily accessible to blind users by scaling the data values to friction rather than shape or size, as in traditional bar charts

Haptic Hybrid Prototyping (HHP): An AR Application for Texture Evaluation with Semantic Content in Product Design

The manufacture of prototypes is costly in economic and temporal terms and in order to carry this out it is necessary to accept certain deviations with respect to the final finishes. This article proposes haptic hybrid prototyping, a haptic-visual product prototyping method created to help product design teams evaluate and select semantic information conveyed between product and user through texturing and ribs of a product in early stages of conceptualization. For the evaluation of this tool, an experiment was realized in which the haptic experience was compared during the interaction with final products and through the HHP. As a result, it was observed that the answers of the interviewees coincided in both situations in 81% of the cases. It was concluded that the HHP enables us to know the semantic information transmitted through haptic-visual means between product and user as well as being able to quantify the clarity with which this information is transmitted. Therefore, this new tool makes it possible to reduce the manufacturing lead time of prototypes as well as the conceptualization phase of the product, providing information on the future success of the product in the market and its economic return

Virtual Texture Generated using Elastomeric Conductive Block Copolymer in Wireless Multimodal Haptic Glove.

Haptic devices are in general more adept at mimicking the bulk properties of materials than they are at mimicking the surface properties. This paper describes a haptic glove capable of producing sensations reminiscent of three types of near-surface properties: hardness, temperature, and roughness. To accomplish this mixed mode of stimulation, three types of haptic actuators were combined: vibrotactile motors, thermoelectric devices, and electrotactile electrodes made from a stretchable conductive polymer synthesized in our laboratory. This polymer consisted of a stretchable polyanion which served as a scaffold for the polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The scaffold was synthesized using controlled radical polymerization to afford material of low dispersity, relatively high conductivity (0.1 S cm-1), and low impedance relative to metals. The glove was equipped with flex sensors to make it possible to control a robotic hand and a hand in virtual reality (VR). In psychophysical experiments, human participants were able to discern combinations of electrotactile, vibrotactile, and thermal stimulation in VR. Participants trained to associate these sensations with roughness, hardness, and temperature had an overall accuracy of 98%, while untrained participants had an accuracy of 85%. Sensations could similarly be conveyed using a robotic hand equipped with sensors for pressure and temperature