ARC: Alignment-based Redirection Controller for Redirected Walking in Complex Environments

We present a novel redirected walking controller based on alignment that allows the user to explore large and complex virtual environments, while minimizing the number of collisions with obstacles in the physical environment. Our alignment-based redirection controller, ARC, steers the user such that their proximity to obstacles in the physical environment matches the proximity to obstacles in the virtual environment as closely as possible. To quantify a controller's performance in complex environments, we introduce a new metric, Complexity Ratio (CR), to measure the relative environment complexity and characterize the difference in navigational complexity between the physical and virtual environments. Through extensive simulation-based experiments, we show that ARC significantly outperforms current state-of-the-art controllers in its ability to steer the user on a collision-free path. We also show through quantitative and qualitative measures of performance that our controller is robust in complex environments with many obstacles. Our method is applicable to arbitrary environments and operates without any user input or parameter tweaking, aside from the layout of the environments. We have implemented our algorithm on the Oculus Quest head-mounted display and evaluated its performance in environments with varying complexity. Our project website is available at https://gamma.umd.edu/arc/

Advancing proxy-based haptic feedback in virtual reality

This thesis advances haptic feedback for Virtual Reality (VR). Our work is guided by Sutherland's 1965 vision of the ultimate display, which calls for VR systems to control the existence of matter. To push towards this vision, we build upon proxy-based haptic feedback, a technique characterized by the use of passive tangible props. The goal of this thesis is to tackle the central drawback of this approach, namely, its inflexibility, which yet hinders it to fulfill the vision of the ultimate display. Guided by four research questions, we first showcase the applicability of proxy-based VR haptics by employing the technique for data exploration. We then extend the VR system's control over users' haptic impressions in three steps. First, we contribute the class of Dynamic Passive Haptic Feedback (DPHF) alongside two novel concepts for conveying kinesthetic properties, like virtual weight and shape, through weight-shifting and drag-changing proxies. Conceptually orthogonal to this, we study how visual-haptic illusions can be leveraged to unnoticeably redirect the user's hand when reaching towards props. Here, we contribute a novel perception-inspired algorithm for Body Warping-based Hand Redirection (HR), an open-source framework for HR, and psychophysical insights. The thesis concludes by proving that the combination of DPHF and HR can outperform the individual techniques in terms of the achievable flexibility of the proxy-based haptic feedback.Diese Arbeit widmet sich haptischem Feedback für Virtual Reality (VR) und ist inspiriert von Sutherlands Vision des ultimativen Displays, welche VR-Systemen die Fähigkeit zuschreibt, Materie kontrollieren zu können. Um dieser Vision näher zu kommen, baut die Arbeit auf dem Konzept proxy-basierter Haptik auf, bei der haptische Eindrücke durch anfassbare Requisiten vermittelt werden. Ziel ist es, diesem Ansatz die für die Realisierung eines ultimativen Displays nötige Flexibilität zu verleihen. Dazu bearbeiten wir vier Forschungsfragen und zeigen zunächst die Anwendbarkeit proxy-basierter Haptik durch den Einsatz der Technik zur Datenexploration. Anschließend untersuchen wir in drei Schritten, wie VR-Systeme mehr Kontrolle über haptische Eindrücke von Nutzern erhalten können. Hierzu stellen wir Dynamic Passive Haptic Feedback (DPHF) vor, sowie zwei Verfahren, die kinästhetische Eindrücke wie virtuelles Gewicht und Form durch Gewichtsverlagerung und Veränderung des Luftwiderstandes von Requisiten vermitteln. Zusätzlich untersuchen wir, wie visuell-haptische Illusionen die Hand des Nutzers beim Greifen nach Requisiten unbemerkt umlenken können. Dabei stellen wir einen neuen Algorithmus zur Body Warping-based Hand Redirection (HR), ein Open-Source-Framework, sowie psychophysische Erkenntnisse vor. Abschließend zeigen wir, dass die Kombination von DPHF und HR proxy-basierte Haptik noch flexibler machen kann, als es die einzelnen Techniken alleine können

Planning Redirection for Dynamic Passive Haptics Using Model Predictive Control

Navigating an immersive, virtual environment (VE) is one of the key challenges when a head-mounted display is used. The most natural way of navigating a virtual environment would be walking. But walking in a large virtual environment is practically impossible unless the user is in an equally large, walkable real environment (RE), i.e. a one-to-one mapping between real and virtual worlds. A promising solution for navigating large virtual spaces in a limited real space, such as a room, is Redirected Walking.Redirected Walking (RDW) uses so-called Redirection Techniques (RETs) to guide the walker away from obstacles in the real world. These techniques modify the mapping between VE and RE depending upon user movements in real-time.Hence, a point in a real environment can be mapped to just about any point in a virtual environment at a particular time. This makes the task of redirecting the user toward an object in the real environment that serves as a proxy for an object in the virtual environment a much more complex problem. This problem ultimately boils down to creating a dynamic map between selected real and virtual world points, i.e. an entire one-to-one map between real and virtual environments is not needed. This dynamic map applies redirections not just to avoid obstacles but also to redirect the user such that whenever the user reaches for an object in the virtual world, he/she senses the proxy object in the real world.Computer Scienc

Evaluating Semi-Natural Travel and Viewing Techniques in Virtual Reality

With seated virtual reality (VR), the use cases based on seating conditions need to be considered while designing the travel and viewing techniques. The most natural method in seated VR, for viewing interactions is the standard 360-degree rotation, for which a swivel chair that spins around the vertical axis is commonly used. However, the VR users will not have the affordances of a swivel chair or the physical space to turn around, all the time. This limits their VR usage based on the availability of certain physical setups. Moreover, for prolonged usage, users might prefer to have convenient viewing interactions by sitting on a couch, not rotating physically all the way around. Our research addresses these scenarios by studying new and existing semi-natural travel and viewing techniques that can be used when full 360-degree rotation is not feasible or is not preferred. Two new techniques, guided head rotation and user-controlled resetting were developed and were compared with existing techniques in three controlled experiments. Standard 360- degree rotation and three joystick-control based viewing techniques (discrete rotation, continuous rotation and continuous rotation with reduced fov) were the existing techniques compared in our experiments. Since the new techniques and some of the existing techniques involve some rotation manipulations that are not natural, they could disorient the users during a virtual experience. So, two VR puzzle games were designed to study the effects of the techniques on spatial awareness of the users. Convenience, simulator sickness, comfort and preferences for home entertainment were the other factors investigated in the experiments. From the experiments, we found out that the results were based on 3D gaming experience of the participants. Participants who played 3D games one or more hours per week had higher tolerance towards the new techniques that had rotational manipulations compared to the participants who did not play any 3D game. Among the joystick rotation techniques, discrete rotation was rated the best by users in terms of simulator sickness. In addition to these experiments, we also present a case study that demonstrates the application of guided head rotation in an experiment that studied natural hand interaction with virtual objects under constrained physical conditions

VR Lab: User Interaction in Virtual Environments using Space and Time Morphing

Virtual Reality (VR) allows exploring changes in space and time that would otherwise be difficult to simulate in the real world. It becomes possible to transform the virtual world by increasing or diminishing distances or playing with time delays. Analysing the adaptability of users to different space-time conditions allows studying human perception and finding the right combination of interaction paradigms. Different methods have been proposed in the literature to offer users intuitive techniques for navigating wide virtual spaces, even if restricted to small physical play areas. Other studies investigate latency tolerance, suggesting humans’ inability to detect slight discrepancies between visual and proprioceptive sensory information. These studies contribute valuable insights for designing immersive virtual experiences and interaction techniques suitable for each task. This dissertation presents the design, implementation, and evaluation of a tangible VR Lab where spatiotemporal morphing scenarios can be studied. As a case study, we restricted the scope of the research to three spatial morphing scenarios and one temporal morphing scenario. The spatial morphing scenarios compared Euclidean and hyperbolic geometries, studied size discordance between physical and virtual objects, and the representation of hands in VR. The temporal morphing scenario investigated from what visual delay the task performance is affected. The users’ adaptability to the different spatiotemporal conditions was assessed based on task completion time, questionnaires, and observed behaviours. The results revealed significant differences between Euclidean and hyperbolic spaces. They also showed a preference for handling virtual and physical objects with concordant sizes, without any virtual representation of the hands. Although task performance was affected from 200 ms onwards, participants considered the ease of the task to be affected only from 500 ms visual delay onwards.A Realidade Virtual (RV) permite explorar mudanças no espaço e no tempo que de outra forma seriam difíceis de simular no mundo real. Torna-se possível transformar o mundo virtual aumentando ou diminuindo as distâncias ou manipulando os atrasos no tempo. A análise da adaptabilidade dos utilizadores a diferentes condições espaço-temporais permite estudar a perceção humana e encontrar a combinação certa de paradigmas de interação. Diferentes métodos têm sido propostos na literatura para oferecer aos utilizadores técnicas intuitivas de navegação em espaços virtuais amplos, mesmo que restritos a pequenas áreas físicas de jogo. Outros estudos investigam a tolerância à latência, sugerindo a incapacidade do ser humano de detetar ligeiras discrepâncias entre a informação sensorial visual e propriocetiva. Estes estudos contribuem com valiosas informações para conceber experiências virtuais imersivas e técnicas de interação adequadas a cada tarefa. Esta dissertação apresenta o desenho, implementação e avaliação de um Laboratório de RV tangível onde podem ser estudados cenários de distorção espaço-temporal. Como estudo de caso, restringimos o âmbito da investigação a três cenários de distorção espacial e um cenário de distorção temporal. Os cenários de distorção espacial compararam geometrias Euclidianas e hiperbólicas, estudaram a discordância de tamanho entre objetos físicos e virtuais, e a representação das mãos em RV. O cenário de distorção temporal investigou a partir de que atraso visual o desempenho da tarefa é afetado. A adaptabilidade dos utilizadores às diferentes condições espaço-temporais foi avaliada com base no tempo de conclusão da tarefa, questionários, e comportamentos observados. Os resultados revelaram diferenças significativas entre os espaços Euclidiano e hiperbólico. Também mostraram a preferência pelo manuseamento de objetos virtuais e físicos com tamanhos concordantes, sem qualquer representação virtual das mãos. Embora o desempenho da tarefa tenha sido afetado a partir dos 200 ms, os participantes consideraram que a facilidade da tarefa só foi afetada a partir dos 500 ms de atraso visual

Multimodality in VR: A survey

Virtual reality (VR) is rapidly growing, with the potential to change the way we create and consume content. In VR, users integrate multimodal sensory information they receive, to create a unified perception of the virtual world. In this survey, we review the body of work addressing multimodality in VR, and its role and benefits in user experience, together with different applications that leverage multimodality in many disciplines. These works thus encompass several fields of research, and demonstrate that multimodality plays a fundamental role in VR; enhancing the experience, improving overall performance, and yielding unprecedented abilities in skill and knowledge transfer

Monitoring companion for industrial robotic processes

For system integrators, optimizing complex industrial robotic applications (e.g. robotised welding) is a difficult and time-consuming task. This procedure is rendered tedious and often very hard to achieve when the operator cannot access the robotic system once in operation, perhaps because the installation is far away or because of the operational environment. In these circumstances, as an alternative to physically visiting the installation site, the system integrator may rely on additional nearby sensors to remotely acquire the necessary process information. While it is hard to completely replace this trial and error approach, it is possible to provide a way to gather process information more effectively that can be used in several robotic installations.This thesis investigates the use of a "monitoring robot" in addition to the task robot(s) that belong to the industrial process to be optimized. The monitoring robot can be equipped with several different sensors and can be moved into close proximity of any installed task robot so that it can be used to collect information from that process during and/or after the operation without interfering. The thesis reviews related work in the industry and in the field of teleoperation to identify the most important challenges in remote monitoring and teleoperation. From the background investigation it is clear that two very important issues are: i) the nature of the teleoperator’s interface and; ii) the efficiency of the shared control between the human operator and the monitoring system. In order to investigate these two issues efficiently it was necessary to create experimental scenarios that operate independently from any application scenario, so an abstract problem domain is created. This way the monitoring system's control and interface can be evaluated in a context that presents challenges that are typical of a remote monitoring task but are not application domain specific. Therefore the validity of the proposed approach can be assessed from a generic and, therefore, more powerful and widely applicable perspective. The monitoring framework developed in this thesis is described, both in the shared control design choices based on virtual fixtures (VF) and the implementation in a 3D visualization environment. The monitoring system developed is evaluated with a usability study with user participants. The usability study aims at assessing the system's performance along with its acceptance and ease of use in a static monitoring task, accompanied by user\hyp{}filled TLX questionnaires. Since future work will apply this system in real robotic welding scenarios, this thesis finally reports some preliminary work in such an application