The design ideal of the invisible computer, prevalent in the vision of ambient intelligence (AmI), has led to a number of interaction challenges. The complex nature of AmI environments together with limited feedback and insufficient means to override the system can result in users who feel frustrated and out of control. In this paper, we explore the potential of visualizing the system state to improve user understanding. We use projectors to overlay the environment with a graphical representation that connects sensors and devices with the actions they trigger and the effects those actions produce. We also provided users with a simple voice-controlled command to cancel the last action. A small first-use study suggested that our technique could indeed improve understanding and support users in forming a reliable mental model.

The work addresses the problem of coping with a diversity of location tracking techniques available in ubiquitous computing environments. We investigate how this diversity can be embedded in the environment in a way that typical difficulties coming from using location-awareness are hidden. We present an approach to improve location-awareness of these environments by means of integrating the knowledge about different location systems into an existing framework for designing pervasive environments in the form of an ontology. Emerging challenges are also discussed in the context of continuous and smooth communication.

Users often find it hard to understand and control the behavior of a Ubicomp system. This gives rise to usability problems and can lead to loss of user trust, which may hamper the acceptance of these systems. We are extending an existing Ubicomp framework to allow users to pose why and why not questions about its behavior. Initial experiments suggest that these questions are easy to use and could help users in understanding how Ubicomp systems work.

The design of interactive software that populates an ambient space is a complex and ad-hoc process with traditional software development approaches. In an ambient space, important building blocks can be both physical objects within the user's reach and software objects accessible from within that space. However, putting many heterogeneous resources together to create a single system mostly requires writing a large amount of glue code before such a system is operational. Besides, users all have their own needs and preferences to interact with various kinds of environments which often means that the system behavior should be adapted to a specific context of use while the system is being used. In this paper we present a methodology to orchestrate resources on an abstract level and hence configure a pervasive computing environment. We use a semantic layer to model behavior and illustrate its use in an application.

The increasing complexity of pervasive computing environments puts the current software development methods to the test. There is a large variation in different types of hardware that need to be addressed. Besides, there is no guarantee the environment does not evolve, making the software developed for the initial environment deprecated and in need for updates or reconfiguration. Software deployed in such an environment should be sufficiently dynamic to cope with new environment configurations, even while the system is in use. This goes beyond coping with new contexts of use and building context-aware systems: while most approaches are mainly focused on how the software behavior adapts according to the changing context in a fixed environment, our approach, ReWiRe, allows the environment configuration to change over time.

Bringing together the physical and digital worlds has been the subject of research for some time now. In particular, a number of successful prototypes that link physical objects with digital information (often called smart object systems) have already been presented. However, a generally accepted architecture to design such systems has not yet emerged. This paper presents a reusable and practical framework for developing smart object applications today. At the basis of our approach lies the use of Semantic Web technology to drive interaction between the physical and digital worlds. We used this framework to develop SemaNews, a novel application that combines the advantages of digital news feeds with those of physical newspapers. To verify the reusability of our architecture, we built a second prototype in a different application domain: STalkingObjects provides the basic components of a store of the future.