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This paper deals with the derivation and the implementation of a flatness based control for a nonlinear ball in tube system as a testbed. For this purpose the system equations are quoted, considering that the system properties are changing in dependence on a positive or a negative fan acceleration. The proof for the ball position as chosen output shows that the system has the attribute flat. On the basis of this proof a precontrol law is calculated, in order to track the output to a predefined reference trajectory exactly, in case of an ideal model and non-occurring disturbances. Within the whole feedforward control the nonlinear static gain of the DC motor is taken into account by the use of an inverse measured characteristic. The feedforward control is combined with a state feedback and an integral controller. The control quality of the closed-loop system is evaluated with a setpoint transition in form of three different trajectories. In this evaluation the performance is compared using the control concept with and without the integral controller. Concluding the disturbance rejection of the ball in tube system is examined.

This paper introduces the SafeHome Simulator system, a set of immersive Virtual Reality Training tools and display systems to train patients in safe discharge procedures in captured environments of their actual houses. The aim is to lower patient readmission by significantly improving discharge planning and training. The SafeHOME Simulator is a project currently under review.

Simulations, such as n-body or smoothed particle hydrodynamics, create large amounts of time variant data that can generally only be visualized non-interactively by rendering the resulting interaction into movies from a fixed viewpoint. This is due to the large amount of unstructured data that make these data incapable of either loading into graphics memory or streaming from disk. The presented approach aims to preserve the interactively navigable 3D structure of the underlying data by reordering and compressing the data in such a way as to optimize playback rates. Additionally, the presented method is able to detect and describe coherent group motion between frames which might be used for analysis.

Background Proprioceptive imprecision is believed to contribute to persistent pain. Detecting imprecision in order to study or treat it remains challenging given the limitations of current tests. Objectives The aim of this study was to determine whether proprioceptive imprecision could be detected in people with neck pain by testing their ability to identify incongruence between true head motion and a false visual reference using the Proprioception Incongruence Detection (PID) Test. Design A cross-sectional study was conducted. Methods Twenty-four people with neck pain and 24 matched controls repeatedly rotated to specific markers within a virtual world and indicated if their true head rotation was more or less than the rotation suggested by the visual feedback. Visual feedback was manipulated at 6 corrections, ranging from 60% of true movement to 140% of true movement. A standard repositioning error (RPE) test as undertaken for comparison. Results Healthy controls were better able to detect incongruence between vision and true head rotation (X̅=75.6%, SD=8.5%) than people with neck pain were (X̅=69.6%, SD=12.7%). The RPE test scores were not different between groups. The PID Test score related to self-reported pain intensity but did not relate to RPE test score. Limitations Causality cannot be established from this cross-sectional study, and further work refining the PID Test is needed for it to offer clinical utility. Conclusions Proprioceptive precision for neck movement appears worse in people with neck pain than in those without neck pain, and the extent of the deficit appears to be related to usual pain severity. The PID Test appears to be a more sensitive test than the RPE test and is likely to be useful for assessment of proprioceptive function in research and clinical settings.

This document introduces a new application for rendering massive LiDAR point cloud data sets of interior environments within highresolution immersive VR display systems. Overall contributions are: to create an application which is able to visualize large-scale point clouds at interactive rates in immersive display environments, to develop a flexible pipeline for processing LiDAR data sets that allows display of both minimally processed and more rigorously processed point clouds, and to provide visualization mechanisms that produce accurate rendering of interior environments to better understand physical aspects of interior spaces. The work introduces three problems with producing accurate immersive rendering of Li-DAR point cloud data sets of interiors and presents solutions to these problems. Rendering performance is compared between the developed application and a previous immersive LiDAR viewer.

Pain is a protective perceptual response shaped by contextual, psychological, and sensory inputs that suggest danger to the body. Sensory cues suggesting that a body part is moving toward a painful position may credibly signal the threat and thereby modulate pain. In this experiment, we used virtual reality to investigate whether manipulating visual proprioceptive cues could alter movement-evoked pain in 24 people with neck pain. We hypothesized that pain would occur at a lesser degree of head rotation when visual feedback overstated true rotation and at a greater degree of rotation when visual feedback understated true rotation. Our hypothesis was clearly supported: when vision overstated the amount of rotation, pain occurred at 7% less rotation than under conditions of accurate visual feedback, and when vision understated rotation, pain occurred at 6% greater rotation than under conditions of accurate visual feedback. We concluded that visual-proprioceptive information modulated the threshold for movement-evoked pain, which suggests that stimuli that become associated with pain can themselves trigger pain. Refereed/Peer-reviewed

Ray tracing is an elegant and intuitive image generation method. The introduction of GPU-accelerated ray tracing and corresponding software frameworks makes this rendering technique a viable option for Augmented Reality applications. Spatial Augmented Reality employs projectors to illuminate physical models and is used in fields that require photorealism, such as design and prototyping. Ray tracing can be used to great effect in this Augmented Reality environment to create scenes of high visual fidelity. However, the peculiarities of SAR systems require that core ray tracing algorithms be adapted to this new rendering environment. This paper highlights the problems involved in using ray tracing in a SAR environment and provides solutions to overcome them. In particular, the following issues are addressed: ray generation, hybrid rendering and view-dependent rendering. Refereed/Peer-reviewed

Spatial Augmented Reality allows the appearance of physical objects to be transformed using projected light. Computer controlled light projection systems have become readily available and cost effective for both commercial and personal use. This chapter explores how large Spatial Augmented Reality systems can be applied to enhanced design mock-ups. Unlike traditional appearance altering techniques such as paints and inks, computer controlled projected light can change the color of a prototype at the touch of a button allowing many different appearances to be evaluated. We present the customized physical-virtual tools we have developed such as our hand held virtual spray painting tool that allows designers to create many customized appearances using only projected light. Finally, we also discuss design parameters of building dedicated projection environments including room layout, hardware selection and interaction considerations.

Effective designs rarely emerge from good structural design or aesthetics alone. It is more often the result of the end product's overall design integrity. Added to this, design is inherently an interdisciplinary collaborative activity. With this in mind, today's tools are not powerful enough to design complex physical environments, such as command control centers or hospital operating theaters. This paper presents the concept of employing projector-based augmented reality techniques to enhance interdisciplinary design processes. Refereed/Peer-reviewed