Browsing by Subject "Haptics"
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Item Open Access From hate to love: how learning can change affective responses to touched materials(Springer Science and Business Media Deutschland GmbH, 2020) Cavdan, M.; Freund, A.; Trieschmann, A.-K.; Doerschner, Katja; Drewing, K.; Nisky, I.; Hartcher-O’Brien, J.; Wiertlewski, M.; Smeets, J.People display systematic affective reactions to specific properties of touched materials. For example, granular materials such as fine sand feel pleasant, while rough materials feel unpleasant. We wondered how far such relationships between sensory material properties and affective responses can be changed by learning. Manipulations in the present experiment aimed at unlearning the previously observed negative relationship between roughness and valence and the positive one between granularity and valence. In the learning phase, participants haptically explored materials that are either very rough or very fine-grained while they simultaneously watched positive or negative stimuli, respectively, from the International Affective Picture System (IAPS). A control group did not interact with granular or rough materials during the learning phase. In the experimental phase, participants rated a representative diverse set of 28 materials according to twelve affective adjectives. We found a significantly weaker relationship between granularity and valence in the experimental group compared to the control group, whereas roughness-valence correlations did not differ between groups. That is, the valence of granular materials was unlearned (i.e., to modify the existing valence of granular materials) but not that of rough materials. These points to differences in the strength of perceptuo-affective relations, which we discuss in terms of hard-wired versus learned connections.Item Open Access Haptic and visual dimensions of perceived softness(Bilkent University, 2017-09) Üstün, Fatma SeyhunExploring the environment with our senses is a prerequisite to successfully and efficiently interact with it. Our senses provide information about what material objects and surfaces are made of and help us to stay clear of icy patches or using the right grip of force when grasping an oily bottle. Compared to other material properties, the perception of softness has received only limited attention in the haptic and visual perception studies. Moreover, in the haptic domain, softness had been thought of synonymously with compliance. Yet, softness can have many dimensions: the softness of silk and jelly are quite different. Although silk and jelly comply with the force that is applied to them in a similar manner, the perception of softness for these compliant materials are quite different. Using a rating task we investigate here the haptic dimensions of perceived softness and compare it to the haptic dimensions derived from vision only. Results of an exploratory factor analysis suggest that for our set of stimuli, softness has indeed more than one qualitative dimension, i.e. compliance, to it. However, factor loadings were more distinct for the haptic domain. Haptic and visual domains provided rather similar information regarding slipperiness, softness, deformability and roughness. There were, however, differences between the two perceptual domains for granularity, stickiness and hairiness. We discuss these results with respect to the role of haptic and visual information in the perception of softness.Item Open Access Haptic discrimination of different types of soft materials(Springer Science and Business Media Deutschland GmbH, 2022-05-20) Cavdan, Müge; Doerschner, Katja; Drewing, KnutWe interact with different types of soft materials on a daily basis such as salt, hand cream, etc. Recently we have shown that soft materials can be described using four perceptual dimensions which are deformability, granularity, viscosity, and surface softness [1]. Here, we investigated whether humans can actually perceive systematic differences in materials that selectively vary along one of these four dimensions as well as how judgments on the different dimensions are correlated to softness judgments. We selected at least two material classes per dimension (e.g., hair gel and hand cream for viscosity) and varied the corresponding feature (e.g., the viscosity of hair gel). Participants ordered four to ten materials from each material class according to their corresponding main feature, and in addition, according to their softness. Rank orders of materials according to the main feature were consistent across participants and repetitions. Rank orders according to softness were correlated either positively or negatively with the judgments along the associated four perceptual dimensions. These findings support our notion of multiple softness dimensions and demonstrate that people can reliably discriminate materials which are artificially varied along each of these softness dimensions. © 2022, The Author(s).Item Open Access Optimizing low-order controllers for haptic systems under delayed feedback(Elsevier, 2013-05) Liacu, B.; Koru, A. T.; Özbay, Hitay; Niculescu, S. -I.; Andriot, C.In this paper, a PD controller design for haptic systems under delayed feedback is considered. More precisely, a complete stability analysis of a haptic system where local dynamics are described by some second-order mechanical dynamics is presented. Next, using two optimization techniques (H∞ and stability, margin optimization) an optimal choice for the controller gains is proposed. The derived results are tested on a three degree-of-freedom real-time experimental platform to illustrate the theoretical results.