Move or Push? Studying Pseudo-Haptic Perceptions Obtained with Motion or Force Input

Pseudo-haptics techniques are interesting alternatives for generating haptic perceptions, which entails the manipulation of haptic perception through the appropriate alteration of primarily visual feedback in response to body movements. However, the use of pseudo-haptics techniques with a motion-input system can sometimes be limited. This paper investigates a novel approach for extending the potential of pseudo-haptics techniques in virtual reality (VR). The proposed approach utilizes a reaction force from force-input as a substitution of haptic cue for the pseudo-haptic perception. The paper introduced a manipulation method in which the vertical acceleration of the virtual hand is controlled by the extent of push-in of a force sensor. Such a force-input manipulation of a virtual body can not only present pseudo-haptics with less physical spaces and be used by more various users including physically handicapped people, but also can present the reaction force proportional to the user's input to the user. We hypothesized that such a haptic force cue would contribute to the pseudo-haptic perception. Therefore, the paper endeavors to investigate the force-input pseudo-haptic perception in a comparison with the motion-input pseudo-haptics. The paper compared force-input and motion-input manipulation in a point of achievable range and resolution of pseudo-haptic weight. The experimental results suggest that the force-input manipulation successfully extends the range of perceptible pseudo-weight by 80\% in comparison to the motion-input manipulation. On the other hand, it is revealed that the motion-input manipulation has 1 step larger number of distinguishable weight levels and is easier to operate than the force-input manipulation.Comment: This paper is now under review for IEEE Transactions on Visualization and Computer Graphic

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

Remote tactile feedback on interactive surfaces

Direct touch input on interactive surfaces has become a predominating standard for the manipulation of digital information in our everyday lives. However, compared to our rich interchange with the physical world, the interaction with touch-based systems is limited in terms of flexibility of input and expressiveness of output. Particularly, the lack of tactile feedback greatly reduces the general usability of a touch-based system and hinders from a productive entanglement of the virtual information with the physical world. This thesis proposes remote tactile feedback as a novel method to provide programmed tactile stimuli supporting direct touch interactions. The overall principle is to spatially decouple the location of touch input (e.g. fingertip or hand) and the location of the tactile sensation on the user's body (e.g. forearm or back). Remote tactile feedback is an alternative concept which avoids particular challenges of existing approaches. Moreover, the principle provides inherent characteristics which can accommodate for the requirements of current and future touch interfaces. To define the design space, the thesis provides a structured overview of current forms of touch surfaces and identifies trends towards non-planar and non-rigid forms with more versatile input mechanisms. Furthermore, a classification highlights limitations of the current methods to generate tactile feedback on touch-based systems. The proposed notion of tactile sensory relocation is a form of sensory substitution. Underlying neurological and psychological principles corroborate the approach. Thus, characteristics of the human sense of touch and principles from sensory substitution help to create a technical and conceptual framework for remote tactile feedback. Three consecutive user studies measure and compare the effects of both direct and remote tactile feedback on the performance and the subjective ratings of the user. Furthermore, the experiments investigate different body locations for the application of tactile stimuli. The results show high subjective preferences for tactile feedback, regardless of its type of application. Additionally, the data reveals no significant differences between the effects of direct and remote stimuli. The results back the feasibility of the approach and provide parameters for the design of stimuli and the effective use of the concept. The main part of the thesis describes the systematical exploration and analysis of the inherent characteristics of remote tactile feedback. Four specific features of the principle are identified: (1) the simplification of the integration of cutaneous stimuli, (2) the transmission of proactive, reactive and detached feedback, (3) the increased expressiveness of tactile sensations and (4) the provision of tactile feedback during multi-touch. In each class, several prototypical remote tactile interfaces are used in evaluations to analyze the concept. For example, the PhantomStation utilizes psychophysical phenomena to reduce the number of single tactile actuators. An evaluation with the prototype compares standard actuator technologies with each other in order to enable simple and scalable implementations. The ThermalTouch prototype creates remote thermal stimuli to reproduce material characteristics on standard touchscreens. The results show a stable rate of virtual object discrimination based on remotely applied temperature profiles. The AutmotiveRTF system is implemented in a vehicle and supports the driver's input on the in-vehicle-infotainment system. A field study with the system focuses on evaluating the effects of proactive and reactive feedback on the user's performance. The main contributions of the dissertation are: First, the thesis introduces the principle of remote tactile feedback and defines a design space for this approach as an alternative method to provide non-visual cues on interactive surfaces. Second, the thesis describes technical examples to rapidly prototype remote tactile feedback systems. Third, these prototypes are deployed in several evaluations which highlight the beneficial subjective and objective effects of the approach. Finally, the thesis presents features and inherent characteristics of remote tactile feedback as a means to support the interaction on today's touchscreens and future interactive surfaces.Die Interaktion mit berührungsempfindlichen Oberflächen ist heute ein Standard für die Manipulation von digitaler Information. Jedoch weist die Bedienung dieser interaktiven Bildschirme starke Einschränkungen hinsichtlich der Flexibilität bei der Eingabe und der Ausdruckskraft der Ausgabe auf, wenn man sie mit den vielfältigen Möglichkeiten des Umgangs mit Objekten in unserer Alltagswelt vergleicht. Besonders die nicht vorhandenen Tastsinnesrückmeldungen vermindern stark die Benutzbarkeit solcher Systeme und verhindern eine effektive Verknüpfung von virtueller Information und physischer Welt. Die vorliegende Dissertation beschreibt den Ansatz der 'distalen taktilen Rückmeldungen' als neuartige Möglichkeit zur Vermittlung programmierter Tastsinnesreize an Benutzer interaktiver Oberflächen. Das Grundprinzip dabei ist die räumliche Trennung zwischen der Eingabe durch Berührung (z.B. mit der Fingerspitze) und dem daraus resultierenden taktilen Reiz am Körper der Benutzer (z.B. am Rücken). Dabei vermeidet das Konzept der distalen taktilen Rückmeldungen einzelne technische und konzeptionelle Nachteile existierender Ansätze. Zusätzlich bringt es Interaktionsmöglichkeiten mit sich, die den Eigenheiten der Interaktion mit aktuellen und auch zukünftigen berührungsempfindlichen Oberflächen Rechnung tragen. Zu Beginn zeigt ein Überblick zu relevanten Arbeiten den aktuellen Forschungstrend hin zu nicht-flachen und verformbaren berührungsempfindlichen Oberflächen sowie zu vielfältigeren Eingabemethoden. Eine Klassifizierung ordnet existierende technische Verfahren zur Erzeugung von künstlichen Tastsinnesreizen und stellt jeweils konzeptuelle und technische Herausforderungen dar. Der in dieser Arbeit vorgeschlagene Ansatz der Verlagerung von Tastsinnesreizen ist eine Form der sensorischen Substitution, zugrunde liegende neurologische und psychologische Prinzipien untermauern das Vorgehen. Die Wirkprinzipien des menschlichen Tastsinnes und die Systeme zur sensorischen Substitution liefern daher konzeptionelle und technische Richtlinien zur Umsetzung der distalen taktilen Rückmeldungen. Drei aufeinander aufbauende Benutzerstudien vergleichen die Auswirkungen von direkten und distalen taktilen Rückmeldungen auf die Leistung und das Verhalten von Benutzern sowie deren subjektive Bewertung der Interaktion. Außerdem werden in den Experimenten die Effekte von Tastsinnesreizen an verschiedenen Körperstellen untersucht. Die Ergebnisse zeigen starke Präferenzen für Tastsinnesrückmeldungen, unabhängig von deren Applikationsort. Die Daten ergeben weiterhin keine signifikanten Unterschiede bei den quantitativen Effekten von direktem und distalen Rückmeldungen. Diese Ergebnisse befürworten die Realisierbarkeit des Ansatzes und zeigen Richtlinien für weitere praktische Umsetzungen auf. Der Hauptteil der Dissertation beschreibt die systematische Untersuchung und Analyse der inhärenten Möglichkeiten, die sich aus der Vermittlung distaler taktiler Rückmeldungen ergeben. Vier verschiedene Charakteristika werden identifiziert: (1) die vereinfachte Integration von Tastsinnesreizen, (2) die Vermittlung von proaktiven, reaktiven und entkoppelten Rückmeldungen, (3) die erhöhte Bandbreite der taktilen Signale und (4) die Darstellung von individuellen Tastsinnesreizen für verschiedene Kontaktpunkte mit der berührungsempfindlichen Oberfläche. Jedes dieser Prinzipien wird durch prototypische Systeme umgesetzt und in Benutzerstudien analysiert. Beispielsweise nutzt das System PhantomStation psychophysikalische Illusionen, um die Anzahl der einzelnen Reizgeber zu reduzieren. In einer Evaluierung des Prototypen werden mehrere Aktuatortechnologien verglichen, um einfache und skalierbare Ansätze zu identifizieren. Der ThermalTouch-Prototyp wird dazu genutzt, distale thermale Reize zu vermitteln, um so Materialeigenschaften auf Berührungsbildschirmen darstellen zu können. Eine Benutzerstudie zeigt, dass sich auf Basis dieser Temperaturverläufe virtuelle Objekte unterscheiden lassen. Das AutomotiveRTF-System wird schließlich in ein Kraftfahrzeug integriert, um den Fahrer bei der Eingabe auf dem Informations- und Unterhaltungssystem zu unterstützen. Eine Feldstudie untersucht die Auswirkungen der proaktiven und reaktiven Rückmeldungen auf die Benutzerleistung. Die vorliegende Dissertation leistet mehrere Beiträge zur Mensch-Maschine-Interaktion: Das Prinzip der distalen taktilen Rückmeldungen wird eingeführt als Alternative zur Erzeugung nicht-visueller Rückmeldungen auf interaktiven Oberflächen. Es werden technische Verfahrensweisen zur prototypischen Implementierung solcher Systeme vorgeschlagen. Diese technischen Prototypen werden in einer Vielzahl verschiedener Benutzerstudien eingesetzt, welche die quantitativen und qualitativen Vorteile des Ansatzes aufzeigen. Schließlich wird gezeigt, wie sich das Prinzip zur Unterstützung heutiger und zukünftiger Interaktionsformen mit berührungsempfindlichen Bildschirmen nutzen lässt

A Haptic System for Depicting Mathematical Graphics for Students with Visual Impairments

When teaching students with visual impairments educators generally rely on tactile tools to depict visual mathematical topics. Tactile media, such as embossed paper and simple manipulable materials, are typically used to convey graphical information. Although these tools are easy to use and relatively inexpensive, they are solely tactile and are not modifiable. Dynamic and interactive technologies such as pin matrices and haptic pens are also commercially available, but tend to be more expensive and less intuitive. This study aims to bridge the gap between easy-to-use tactile tools and dynamic, interactive technologies in order to facilitate the haptic learning of mathematical concepts. We developed an haptic assistive device using a Tanvas electrostatic touchscreen that provides the user with multimodal (haptic, auditory, and visual) output. Three methodological steps comprise this research: 1) a systematic literature review of the state of the art in the design and testing of tactile and haptic assistive devices, 2) a user-centered system design, and 3) testing of the system’s effectiveness via a usability study. The electrostatic touchscreen exhibits promise as an assistive device for displaying visual mathematical elements via the haptic modality

Mixed Structural Models for 3D Audio in Virtual Environments

In the world of ICT, strategies for innovation and development are increasingly focusing on applications that require spatial representation and real-time interaction with and within 3D media environments. One of the major challenges that such applications have to address is user-centricity, reflecting e.g. on developing complexity-hiding services so that people can personalize their own delivery of services. In these terms, multimodal interfaces represent a key factor for enabling an inclusive use of the new technology by everyone. In order to achieve this, multimodal realistic models that describe our environment are needed, and in particular models that accurately describe the acoustics of the environment and communication through the auditory modality. Examples of currently active research directions and application areas include 3DTV and future internet, 3D visual-sound scene coding, transmission and reconstruction and teleconferencing systems, to name but a few. The concurrent presence of multimodal senses and activities make multimodal virtual environments potentially flexible and adaptive, allowing users to switch between modalities as needed during the continuously changing conditions of use situation. Augmentation through additional modalities and sensory substitution techniques are compelling ingredients for presenting information non-visually, when the visual bandwidth is overloaded, when data are visually occluded, or when the visual channel is not available to the user (e.g., for visually impaired people). Multimodal systems for the representation of spatial information will largely benefit from the implementation of audio engines that have extensive knowledge of spatial hearing and virtual acoustics. Models for spatial audio can provide accurate dynamic information about the relation between the sound source and the surrounding environment, including the listener and his/her body which acts as an additional filter. Indeed, this information cannot be substituted by any other modality (i.e., visual or tactile). Nevertheless, today's spatial representation of audio within sonification tends to be simplistic and with poor interaction capabilities, being multimedia systems currently focused on graphics processing mostly, and integrated with simple stereo or multi-channel surround-sound. On a much different level lie binaural rendering approaches based on headphone reproduction, taking into account that possible disadvantages (e.g. invasiveness, non-flat frequency responses) are counterbalanced by a number of desirable features. Indeed, these systems might control and/or eliminate reverberation and other acoustic effects of the real listening space, reduce background noise, and provide adaptable and portable audio displays, which are all relevant aspects especially in enhanced contexts. Most of the binaural sound rendering techniques currently exploited in research rely on the use of Head-Related Transfer Functions (HRTFs), i.e. peculiar filters that capture the acoustic effects of the human head and ears. HRTFs allow loyal simulation of the audio signal that arrives at the entrance of the ear canal as a function of the sound source's spatial position. HRTF filters are usually presented under the form of acoustic signals acquired on dummy heads built according to mean anthropometric measurements. Nevertheless, anthropometric features of the human body have a key role in HRTF shaping: several studies have attested how listening to non-individual binaural sounds results in evident localization errors. On the other hand, individual HRTF measurements on a significant number of subjects result both time- and resource-expensive. Several techniques for synthetic HRTF design have been proposed during the last two decades and the most promising one relies on structural HRTF models. In this revolutionary approach, the most important effects involved in spatial sound perception (acoustic delays and shadowing due to head diffraction, reflections on pinna contours and shoulders, resonances inside the ear cavities) are isolated and modeled separately with a corresponding filtering element. HRTF selection and modeling procedures can be determined by physical interpretation: parameters of each rendering blocks or selection criteria can be estimated from real and simulated data and related to anthropometric geometries. Effective personal auditory displays represent an innovative breakthrough for a plethora of applications and structural approach can also allow for effective scalability depending on the available computational resources or bandwidth. Scenes with multiple highly realistic audiovisual objects are easily managed exploiting parallelism of increasingly ubiquitous GPUs (Graphics Processing Units). Building individual headphone equalization with perceptually robust inverse filtering techniques represents a fundamental step towards the creation of personal virtual auditory displays (VADs). To this regard, several examples might benefit from these considerations: multi-channel downmix over headphones, personal cinema, spatial audio rendering in mobile devices, computer-game engines and individual binaural audio standards for movie and music production. This thesis presents a family of approaches that overcome the current limitations of headphone-based 3D audio systems, aiming at building personal auditory displays through structural binaural audio models for an immersive sound reproduction. The resulting models allow for an interesting form of content adaptation and personalization, since they include parameters related to the user's anthropometry in addition to those related to the sound sources and the environment. The covered research directions converge to a novel framework for synthetic HRTF design and customization that combines the structural modeling paradigm with other HRTF selection techniques (inspired by non-individualized HRTF selection procedures) and represents the main novel contribution of this thesis: the Mixed Structural Modeling (MSM) approach considers the global HRTF as a combination of structural components, which can be chosen to be either synthetic or recorded components. In both cases, customization is based on individual anthropometric data, which are used to either fit the model parameters or to select a measured/simulated component within a set of available responses. The definition and experimental validation of the MSM approach addresses several pivotal issues towards the acquisition and delivery of binaural sound scenes and designing guidelines for personalized 3D audio virtual environments holding the potential of novel forms of customized communication and interaction with sound and music content. The thesis also presents a multimodal interactive system which is used to conduct subjective test on multi-sensory integration in virtual environments. Four experimental scenarios are proposed in order to test the capabilities of auditory feedback jointly to tactile or visual modalities. 3D audio feedback related to user’s movements during simple target following tasks is tested as an applicative example of audio-visual rehabilitation system. Perception of direction of footstep sounds interactively generated during walking and provided through headphones highlights how spatial information can clarify the semantic congruence between movement and multimodal feedback. A real time, physically informed audio-tactile interactive system encodes spatial information in the context of virtual map presentation with particular attention to orientation and mobility (O&M) learning processes addressed to visually impaired people. Finally, an experiment analyzes the haptic estimation of size of a virtual 3D object (a stair-step) whereas the exploration is accompanied by a real-time generated auditory feedback whose parameters vary as a function of the height of the interaction point. The collected data from these experiments suggest that well-designed multimodal feedback, exploiting 3D audio models, can definitely be used to improve performance in virtual reality and learning processes in orientation and complex motor tasks, thanks to the high level of attention, engagement, and presence provided to the user. The research framework, based on the MSM approach, serves as an important evaluation tool with the aim of progressively determining the relevant spatial attributes of sound for each application domain. In this perspective, such studies represent a novelty in the current literature on virtual and augmented reality, especially concerning the use of sonification techniques in several aspects of spatial cognition and internal multisensory representation of the body. This thesis is organized as follows. An overview of spatial hearing and binaural technology through headphones is given in Chapter 1. Chapter 2 is devoted to the Mixed Structural Modeling formalism and philosophy. In Chapter 3, topics in structural modeling for each body component are studied, previous research and two new models, i.e. near-field distance dependency and external-ear spectral cue, are presented. Chapter 4 deals with a complete case study of the mixed structural modeling approach and provides insights about the main innovative aspects of such modus operandi. Chapter 5 gives an overview of number of a number of proposed tools for the analysis and synthesis of HRTFs. System architectural guidelines and constraints are discussed in terms of real-time issues, mobility requirements and customized audio delivery. In Chapter 6, two case studies investigate the behavioral importance of spatial attribute of sound and how continuous interaction with virtual environments can benefit from using spatial audio algorithms. Chapter 7 describes a set of experiments aimed at assessing the contribution of binaural audio through headphones in learning processes of spatial cognitive maps and exploration of virtual objects. Finally, conclusions are drawn and new research horizons for further work are exposed in Chapter 8

Touching is believing: creating illusions and feeling of embodiment with mid-air haptic technology

Over the last two decades, the sense of touch has received new attention from the scientific community.Several haptic devices have been developed to address the complexity of the sense of touch, the latest addition being mid-air (contactless) haptic technology. An interesting series of previous research has suggested an easier way to tackle the complexity of designing convincing tactile sensations by exploiting tactile illusions. Tactile illusions rely on perceptual shortcuts based on the psychophysics of the tactile receptors. Currently, studies exploring the perceptual space of mid-air haptics and its applicability in the tactile illusions field are still limited in number. This thesis aims to contribute to the field of Human-Computer Interaction (HCI) by investigating the perceptual design space of ultrasonic mid-air haptics technology. Specifically, in a first set of three studies, we investigate the absolute thresholds (minimal amount of a property of astimulus that a user can detect) for control points (CP) at different frequencies on the hand and arm (Study 1). Then we investigate the optimal sampling rate needed to drive the device in an optimal fashion and its relationship with shape size (Study 2). Next, we apply a new technique to increase users’ performance in a shape discrimination task (Study 3). In Study 4, we start the exploration of a tactile illusion of movement using contact touch and later, we apply a similar procedure to investigate the feasibility of creating a tactile illusion of movement between the two non-interconnected hands by using mid-air touch (Study 5). Finally, in Study 6, we explore our sense of touch in VR, while providing an illusion of rain drops through mid-air haptics, to recreate a virtual hand illusion (VHI) to explore the boundaries of our sense of embodiment. Therefore, the contribution of this work is threefold: a) we contribute by adding new knowledge on the psychophysical space for mid-air haptics, b) we test the potential to create realistic tactile sensations by exploiting tactile illusions with mid-air haptic technology, and c) we demonstrate how tactile illusions mediated by mid-air haptics can convey a sense of embodiment in VR environments

Sensory and cognitive factors in multi-digit touch, and its integration with vision

Every tactile sensation – an itch, a kiss, a hug, a pen gripped between fingers, a soft fabric brushing against the skin – is experienced in relation to the body. Normally, they occur somewhere on the body’s surface – they have spatiality. This sense of spatiality is what allows us to perceive a partner’s caress in terms of its changing location on the skin, its movement direction, speed, and extent. How this spatiality arises and how it is experienced is a thriving research topic, compelled by growing interest in the nature of tactile experiences from product design to brain-machine interfaces. The present thesis adds to this flourishing area of research by examining the unified spatial quality of touch. How does distinct spatial information converge from separate areas of the body surface to give rise to our normal unified experience of touch? After explaining the importance of this question in Chapter 1, a novel paradigm to tackle this problem will be presented, whereby participants are asked to estimate the average direction of two stimuli that are simultaneously moved across two different fingerpads. This paradigm is a laboratory analogue of the more ecological task of representing the overall movement of an object held between multiple fingers. An EEG study in Chapter 2 will reveal a brain mechanism that could facilitate such aggregated perception. Next, by characterising participants’ performance not just in terms of error rates, but by considering perceptual sensitivity, bias, precision, and signal weighting, a series of psychophysical experiments will show that this aggregation ability differs for within- and between-hand perception (Chapter 3), is independent from somatotopically-defined circuitry (Chapter 4) and arises after proprioceptive input about hand posture is accounted for (Chapter 5). Finally, inspired by the demand for integrated tactile and visual experience in virtual reality and the potential of tactile interface to aid navigation, Chapter 6 will examine the contribution of tactile spatiality on visual spatial experience. Ultimately, the present thesis will reveal sensory factors that limit precise representation of concurrently occurring dynamic tactile events. It will point to cognitive strategies the brain may employ to overcome those limitations to tactually perceive coherent objects. As such, this thesis advances somatosensory research beyond merely examining the selectivity to and discrimination between experienced tactile inputs, to considering the unified experience of touch despite distinct stimulus elements. The findings also have practical implications for the design of functional tactile interfaces

HapticHead - Augmenting Reality via Tactile Cues

Information overload is increasingly becoming a challenge in today's world. Humans have only a limited amount of attention to allocate between sensory channels and tend to miss or misjudge critical sensory information when multiple activities are going on at the same time. For example, people may miss the sound of an approaching car when walking across the street while looking at their smartphones. Some sensory channels may also be impaired due to congenital or acquired conditions. Among sensory channels, touch is often experienced as obtrusive, especially when it occurs unexpectedly. Since tactile actuators can simulate touch, targeted tactile stimuli can provide users of virtual reality and augmented reality environments with important information for navigation, guidance, alerts, and notifications. In this dissertation, a tactile user interface around the head is presented to relieve or replace a potentially impaired visual channel, called \emph{HapticHead}. It is a high-resolution, omnidirectional, vibrotactile display that presents general, 3D directional, and distance information through dynamic tactile patterns. The head is well suited for tactile feedback because it is sensitive to mechanical stimuli and provides a large spherical surface area that enables the display of precise 3D information and allows the user to intuitively rotate the head in the direction of a stimulus based on natural mapping. Basic research on tactile perception on the head and studies on various use cases of head-based tactile feedback are presented in this thesis. Several investigations and user studies have been conducted on (a) the funneling illusion and localization accuracy of tactile stimuli around the head, (b) the ability of people to discriminate between different tactile patterns on the head, (c) approaches to designing tactile patterns for complex arrays of actuators, (d) increasing the immersion and presence level of virtual reality applications, and (e) assisting people with visual impairments in guidance and micro-navigation. In summary, tactile feedback around the head was found to be highly valuable as an additional information channel in various application scenarios. Most notable is the navigation of visually impaired individuals through a micro-navigation obstacle course, which is an order of magnitude more accurate than the previous state-of-the-art, which used a tactile belt as a feedback modality. The HapticHead tactile user interface's ability to safely navigate people with visual impairments around obstacles and on stairs with a mean deviation from the optimal path of less than 6~cm may ultimately improve the quality of life for many people with visual impairments.Die Informationsüberlastung wird in der heutigen Welt zunehmend zu einer Herausforderung. Der Mensch hat nur eine begrenzte Menge an Aufmerksamkeit, die er zwischen den Sinneskanälen aufteilen kann, und neigt dazu, kritische Sinnesinformationen zu verpassen oder falsch einzuschätzen, wenn mehrere Aktivitäten gleichzeitig ablaufen. Zum Beispiel können Menschen das Geräusch eines herannahenden Autos überhören, wenn sie über die Straße gehen und dabei auf ihr Smartphone schauen. Einige Sinneskanäle können auch aufgrund von angeborenen oder erworbenen Erkrankungen beeinträchtigt sein. Unter den Sinneskanälen wird Berührung oft als aufdringlich empfunden, besonders wenn sie unerwartet auftritt. Da taktile Aktoren Berührungen simulieren können, können gezielte taktile Reize den Benutzern von Virtual- und Augmented Reality Anwendungen wichtige Informationen für die Navigation, Führung, Warnungen und Benachrichtigungen liefern. In dieser Dissertation wird eine taktile Benutzeroberfläche um den Kopf herum präsentiert, um einen möglicherweise beeinträchtigten visuellen Kanal zu entlasten oder zu ersetzen, genannt \emph{HapticHead}. Es handelt sich um ein hochauflösendes, omnidirektionales, vibrotaktiles Display, das allgemeine, 3D-Richtungs- und Entfernungsinformationen durch dynamische taktile Muster darstellt. Der Kopf eignet sich gut für taktiles Feedback, da er empfindlich auf mechanische Reize reagiert und eine große sphärische Oberfläche bietet, die die Darstellung präziser 3D-Informationen ermöglicht und es dem Benutzer erlaubt, den Kopf aufgrund der natürlichen Zuordnung intuitiv in die Richtung eines Reizes zu drehen. Grundlagenforschung zur taktilen Wahrnehmung am Kopf und Studien zu verschiedenen Anwendungsfällen von kopfbasiertem taktilem Feedback werden in dieser Arbeit vorgestellt. Mehrere Untersuchungen und Nutzerstudien wurden durchgeführt zu (a) der Funneling Illusion und der Lokalisierungsgenauigkeit von taktilen Reizen am Kopf, (b) der Fähigkeit von Menschen, zwischen verschiedenen taktilen Mustern am Kopf zu unterscheiden, (c) Ansätzen zur Gestaltung taktiler Muster für komplexe Arrays von Aktoren, (d) der Erhöhung des Immersions- und Präsenzgrades von Virtual-Reality-Anwendungen und (e) der Unterstützung von Menschen mit Sehbehinderungen bei der Führung und Mikronavigation. Zusammenfassend wurde festgestellt, dass taktiles Feedback um den Kopf herum als zusätzlicher Informationskanal in verschiedenen Anwendungsszenarien sehr wertvoll ist. Am interessantesten ist die Navigation von sehbehinderten Personen durch einen Mikronavigations-Hindernisparcours, welche um eine Größenordnung präziser ist als der bisherige Stand der Technik, der einen taktilen Gürtel als Feedback-Modalität verwendete. Die Fähigkeit der taktilen Benutzerschnittstelle HapticHead, Menschen mit Sehbehinderungen mit einer mittleren Abweichung vom optimalen Pfad von weniger als 6~cm sicher um Hindernisse und auf Treppen zu navigieren, kann letztendlich die Lebensqualität vieler Menschen mit Sehbehinderungen verbessern