Rapid prototyping of ubiquitous computing environments

Ubiquitous computing raises new usability challenges that cut across design and development. We are particularly interested in environments enhanced with sensors, public displays and personal devices. How can prototypes be used to explore the users' mobility and interaction, both explicitly and implicitly, to access services within these environments? Because of the potential cost of development and design failure, these systems must be explored using early assessment techniques and versions of the systems that could disrupt if deployed in the target environment. These techniques are required to evaluate alternative solutions before making the decision to deploy the system on location. This is crucial for a successful development, that anticipates potential user problems, and reduces the cost of redesign. This thesis reports on the development of a framework for the rapid prototyping and analysis of ubiquitous computing environments that facilitates the evaluation of design alternatives. It describes APEX, a framework that brings together an existing 3D Application Server with a modelling tool. APEX-based prototypes enable users to navigate a virtual world simulation of the envisaged ubiquitous environment. By this means users can experience many of the features of the proposed design. Prototypes and their simulations are generated in the framework to help the developer understand how the user might experience the system. These are supported through three different layers: a simulation layer (using a 3D Application Server); a modelling layer (using a modelling tool) and a physical layer (using external devices and real users). APEX allows the developer to move between these layers to evaluate different features. It supports exploration of user experience through observation of how users might behave with the system as well as enabling exhaustive analysis based on models. The models support checking of properties based on patterns. These patterns are based on ones that have been used successfully in interactive system analysis in other contexts. They help the analyst to generate and verify relevant properties. Where these properties fail then scenarios suggested by the failure provide an important aid to redesign.

Integrating eye tracking in virtual reality for stroke rehabilitation

This thesis reports on research done for the integration of eye tracking technology into virtual reality environments, with the goal of using it in rehabilitation of patients who suffered from stroke. For the last few years, eye tracking has been a focus on medical research, used as an assistive tool  to help people with disabilities interact with new technologies  and as an assessment tool  to track the eye gaze during computer interactions. However, tracking more complex gaze behaviors and relating them to motor deficits in people with disabilities is an area that has not been fully explored, therefore it became the focal point of this research. During the research, two exploratory studies were performed in which eye tracking technology was integrated in the context of a newly created virtual reality task to assess the impact of stroke. Using an eye tracking device and a custom virtual task, the system developed is able to monitor the eye gaze pattern changes over time in patients with stroke, as well as allowing their eye gaze to function as an input for the task. Based on neuroscientific hypotheses of upper limb motor control, the studies aimed at verifying the differences in gaze patterns during the observation and execution of the virtual goal-oriented task in stroke patients (N=10), and also to assess normal gaze behavior in healthy participants (N=20). Results were found consistent and supported the hypotheses formulated, showing that eye gaze could be used as a valid assessment tool on these patients. However, the findings of this first exploratory approach are limited in order to fully understand the effect of stroke on eye gaze behavior. Therefore, a novel model-driven paradigm is proposed to further understand the relation between the neuronal mechanisms underlying goal-oriented actions and eye gaze behavior.