Modeling of frictional forces during bare-finger interactions with solid surfaces

Touching an object with our fingers yields frictional forces that allow us to perceive and explore its texture, shape, and other features, facilitating grasping and manipulation. While the relevance of dynamic frictional forces to sensory and motor function in the hand is well established, the way that they reflect the shape, features, and composition of touched objects is poorly understood. Haptic displays -electronic interfaces for stimulating the sense of touch- often aim to elicit the perceptual experience of touching real surfaces by delivering forces to the fingers that mimic those felt when touching real surfaces. However, the design and applications of such displays have been limited by the lack of knowledge about what forces are felt during real touch interactions. This represents a major gap in current knowledge about tactile function and haptic engineering. This dissertation addresses some aspects that would assist in their understanding. The goal of this research was to measure, characterize, and model frictional forces produced by a bare finger sliding over surfaces of multiple shapes. The major contributions of this work are (1) the design and development of a sensing system for capturing fingertip motion and forces during tactile exploration of real surfaces; (2) measurement and characterization of contact forces and the deformation of finger tissues during sliding over relief surfaces; (3) the development of a low order model of frictional force production based on surface specifications; (4) the analysis and modeling of contact geometry, interfacial mechanics, and their effects in frictional force production during tactile exploration of relief surfaces. This research aims to guide the design of algorithms for the haptic rendering of surface textures and shape. Such algorithms can be used to enhance human-machine interfaces, such as touch-screen displays, by (1) enabling users to feel surface characteristics also presented visually; (2) facilitating interaction with these devices; and (3) reducing the need for visual input to interact with them.Ph.D., Electrical Engineering -- Drexel University, 201

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 12th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2020, held in Leiden, The Netherlands, in September 2020. The 60 papers presented in this volume were carefully reviewed and selected from 111 submissions. The were organized in topical sections on haptic science, haptic technology, and haptic applications. This year's focus is on accessibility

Tribological interactions of the finger pad and tactile displays

This thesis summarise the results of an investigation of the tribological interactions of the human finger pad with different surfaces and tactile displays. In the wide range of analyses of the mechanical properties of the finger pad, an attempt has been made to explain the nature of the interactions based on critical material parameters and experimental data. The experimental data are presented together with detailed modelling of the contact mechanics of the finger pad compressed against a smooth flat surface. Based on the model and the experimental data, it was possible to account of the loading behaviour of a finger pad and derive the Young’s modulus of the fingerprint ridges. The frictional measurements of a finger pad against smooth flat surfaces are consistent with an occlusion mechanism that is governed by first order kinetics. In contrast, measurements against a rough surface demonstrated that the friction is unaffected by occlusion since Coulombic slip was exhibited. The thesis includes an investigation of critical parameters such as the contact area. It has been shown that four characteristic length scales, rather than just two as previously assumed, are required to describe the contact mechanics of the finger pad. In addition, there are two characteristic times respectively associated with the growth rates of junctions formed by the finger pad ridges and of the real area of contact. These length and time scales are important in understanding how the Archardian-Hertzian transition drives both the large increase of friction and the reduction of the areal load index during persisting finger contacts with impermeable surfaces. Established and novel models were evaluated with statistically meaningful experiments for phenomena such as lateral displacement, electrostatic forces and squeeze-film that have advanced applications

Novel haptic interface For viewing 3D images

In recent years there has been an explosion of devices and systems capable of displaying stereoscopic 3D images. While these systems provide an improved experience over traditional bidimensional displays they often fall short on user immersion. Usually these systems only improve depth perception by relying on the stereopsis phenomenon. We propose a system that improves the user experience and immersion by having a position dependent rendering of the scene and the ability to touch the scene. This system uses depth maps to represent the geometry of the scene. Depth maps can be easily obtained on the rendering process or can be derived from the binocular-stereo images by calculating their horizontal disparity. This geometry is then used as an input to be rendered in a 3D display, do the haptic rendering calculations and have a position depending render of the scene. The author presents two main contributions. First, since the haptic devices have a finite work space and limited resolution, we used what we call detail mapping algorithms. These algorithms compress geometry information contained in a depth map, by reducing the contrast among pixels, in such a way that it can be rendered into a limited resolution display medium without losing any detail. Second, the unique combination of a depth camera as a motion capturing system, a 3D display and haptic device to enhance user experience. While developing this system we put special attention on the cost and availability of the hardware. We decided to use only off-the-shelf, mass consumer oriented hardware so our experiments can be easily implemented and replicated. As an additional benefit the total cost of the hardware did not exceed the one thousand dollars mark making it affordable for many individuals and institutions

On the critical role of the sensorimotor loop on the design of interaction techniques and interactive devices

People interact with their environment thanks to their perceptual and motor skills. This is the way they both use objects around them and perceive the world around them. Interactive systems are examples of such objects. Therefore to design such objects, we must understand how people perceive them and manipulate them. For example, haptics is both related to the human sense of touch and what I call the motor ability. I address a number of research questions related to the design and implementation of haptic, gestural, and touch interfaces and present examples of contributions on these topics. More interestingly, perception, cognition, and action are not separated processes, but an integrated combination of them called the sensorimotor loop. Interactive systems follow the same overall scheme, with differences that make the complementarity of humans and machines. The interaction phenomenon is a set of connections between human sensorimotor loops, and interactive systems execution loops. It connects inputs with outputs, users and systems, and the physical world with cognition and computing in what I call the Human-System loop. This model provides a complete overview of the interaction phenomenon. It helps to identify the limiting factors of interaction that we can address to improve the design of interaction techniques and interactive devices.Les humains interagissent avec leur environnement grâce à leurs capacités perceptives et motrices. C'est ainsi qu'ils utilisent les objets qui les entourent et perçoivent le monde autour d'eux. Les systèmes interactifs sont des exemples de tels objets. Par conséquent, pour concevoir de tels objets, nous devons comprendre comment les gens les perçoivent et les manipulent. Par exemple, l'haptique est à la fois liée au sens du toucher et à ce que j'appelle la capacité motrice. J'aborde un certain nombre de questions de recherche liées à la conception et à la mise en œuvre d'interfaces haptiques, gestuelles et tactiles et je présente des exemples de contributions sur ces sujets. Plus intéressant encore, la perception, la cognition et l'action ne sont pas des processus séparés, mais une combinaison intégrée d'entre eux appelée la boucle sensorimotrice. Les systèmes interactifs suivent le même schéma global, avec des différences qui forme la complémentarité des humains et des machines. Le phénomène d'interaction est un ensemble de connexions entre les boucles sensorimotrices humaines et les boucles d'exécution des systèmes interactifs. Il relie les entrées aux sorties, les utilisateurs aux systèmes, et le monde physique à la cognition et au calcul dans ce que j'appelle la boucle Humain-Système. Ce modèle fournit un aperçu complet du phénomène d'interaction. Il permet d'identifier les facteurs limitatifs de l'interaction que nous pouvons aborder pour améliorer la conception des techniques d'interaction et des dispositifs interactifs

Musical Haptics

Haptic Musical Instruments; Haptic Psychophysics; Interface Design and Evaluation; User Experience; Musical Performanc

Musical Haptics

Haptic Musical Instruments; Haptic Psychophysics; Interface Design and Evaluation; User Experience; Musical Performanc

Tabletop tangible maps and diagrams for visually impaired users

En dépit de leur omniprésence et de leur rôle essentiel dans nos vies professionnelles et personnelles, les représentations graphiques, qu'elles soient numériques ou sur papier, ne sont pas accessibles aux personnes déficientes visuelles car elles ne fournissent pas d'informations tactiles. Par ailleurs, les inégalités d'accès à ces représentations ne cessent de s'accroître ; grâce au développement de représentations graphiques dynamiques et disponibles en ligne, les personnes voyantes peuvent non seulement accéder à de grandes quantités de données, mais aussi interagir avec ces données par le biais de fonctionnalités avancées (changement d'échelle, sélection des données à afficher, etc.). En revanche, pour les personnes déficientes visuelles, les techniques actuellement utilisées pour rendre accessibles les cartes et les diagrammes nécessitent l'intervention de spécialistes et ne permettent pas la création de représentations interactives. Cependant, les récentes avancées dans le domaine de l'adaptation automatique de contenus laissent entrevoir, dans les prochaines années, une augmentation de la quantité de contenus adaptés. Cette augmentation doit aller de pair avec le développement de dispositifs utilisables et abordables en mesure de supporter l'affichage de représentations interactives et rapidement modifiables, tout en étant accessibles aux personnes déficientes visuelles. Certains prototypes de recherche s'appuient sur une représentation numérique seulement : ils peuvent être instantanément modifiés mais ne fournissent que très peu de retour tactile, ce qui rend leur exploration complexe d'un point de vue cognitif et impose de fortes contraintes sur le contenu. D'autres prototypes s'appuient sur une représentation numérique et physique : bien qu'ils puissent être explorés tactilement, ce qui est un réel avantage, ils nécessitent un support tactile qui empêche toute modification rapide. Quant aux dispositifs similaires à des tablettes Braille, mais avec des milliers de picots, leur coût est prohibitif. L'objectif de cette thèse est de pallier les limitations de ces approches en étudiant comment développer des cartes et diagrammes interactifs physiques, modifiables et abordables. Pour cela, nous nous appuyons sur un type d'interface qui a rarement été étudié pour des utilisateurs déficients visuels : les interfaces tangibles, et plus particulièrement les interfaces tangibles sur table. Dans ces interfaces, des objets physiques représentent des informations numériques et peuvent être manipulés par l'utilisateur pour interagir avec le système, ou par le système lui-même pour refléter un changement du modèle numérique - on parle alors d'interfaces tangibles sur tables animées, ou actuated. Grâce à la conception, au développement et à l'évaluation de trois interfaces tangibles sur table (les Tangible Reels, la Tangible Box et BotMap), nous proposons un ensemble de solutions techniques répondant aux spécificités des interfaces tangibles pour des personnes déficientes visuelles, ainsi que de nouvelles techniques d'interaction non-visuelles, notamment pour la reconstruction d'une carte ou d'un diagramme et l'exploration de cartes de type " Pan & Zoom ". D'un point de vue théorique, nous proposons aussi une nouvelle classification pour les dispositifs interactifs accessibles.Despite their omnipresence and essential role in our everyday lives, online and printed graphical representations are inaccessible to visually impaired people because they cannot be explored using the sense of touch. The gap between sighted and visually impaired people's access to graphical representations is constantly growing due to the increasing development and availability of online and dynamic representations that not only give sighted people the opportunity to access large amounts of data, but also to interact with them using advanced functionalities such as panning, zooming and filtering. In contrast, the techniques currently used to make maps and diagrams accessible to visually impaired people require the intervention of tactile graphics specialists and result in non-interactive tactile representations. However, based on recent advances in the automatic production of content, we can expect in the coming years a growth in the availability of adapted content, which must go hand-in-hand with the development of affordable and usable devices. In particular, these devices should make full use of visually impaired users' perceptual capacities and support the display of interactive and updatable representations. A number of research prototypes have already been developed. Some rely on digital representation only, and although they have the great advantage of being instantly updatable, they provide very limited tactile feedback, which makes their exploration cognitively demanding and imposes heavy restrictions on content. On the other hand, most prototypes that rely on digital and physical representations allow for a two-handed exploration that is both natural and efficient at retrieving and encoding spatial information, but they are physically limited by the use of a tactile overlay, making them impossible to update. Other alternatives are either extremely expensive (e.g. braille tablets) or offer a slow and limited way to update the representation (e.g. maps that are 3D-printed based on users' inputs). In this thesis, we propose to bridge the gap between these two approaches by investigating how to develop physical interactive maps and diagrams that support two-handed exploration, while at the same time being updatable and affordable. To do so, we build on previous research on Tangible User Interfaces (TUI) and particularly on (actuated) tabletop TUIs, two fields of research that have surprisingly received very little interest concerning visually impaired users. Based on the design, implementation and evaluation of three tabletop TUIs (the Tangible Reels, the Tangible Box and BotMap), we propose innovative non-visual interaction techniques and technical solutions that will hopefully serve as a basis for the design of future TUIs for visually impaired users, and encourage their development and use. We investigate how tangible maps and diagrams can support various tasks, ranging from the (re)construction of diagrams to the exploration of maps by panning and zooming. From a theoretical perspective we contribute to the research on accessible graphical representations by highlighting how research on maps can feed research on diagrams and vice-versa. We also propose a classification and comparison of existing prototypes to deliver a structured overview of current research

Musical Haptics

This Open Access book offers an original interdisciplinary overview of the role of haptic feedback in musical interaction. Divided into two parts, part I examines the tactile aspects of music performance and perception, discussing how they affect user experience and performance in terms of usability, functionality and perceived quality of musical instruments. Part II presents engineering, computational, and design approaches and guidelines that have been applied to render and exploit haptic feedback in digital musical interfaces. Musical Haptics introduces an emerging field that brings together engineering, human-computer interaction, applied psychology, musical aesthetics, and music performance. The latter, defined as the complex system of sensory-motor interactions between musicians and their instruments, presents a well-defined framework in which to study basic psychophysical, perceptual, and biomechanical aspects of touch, all of which will inform the design of haptic musical interfaces. Tactile and proprioceptive cues enable embodied interaction and inform sophisticated control strategies that allow skilled musicians to achieve high performance and expressivity. The use of haptic feedback in digital musical interfaces is expected to enhance user experience and performance, improve accessibility for disabled persons, and provide an effective means for musical tuition and guidance