Computing devices and applications are now used beyond the desktop, in diverse environments, and this trend toward ubiquitous computing is accelerating. One challenge that remains in this emerging research field is the ability to enhance the behavior of any application by informing it of the context of its use. By context, we refer to any information that characterizes a situation related to the interaction between humans, applications and the surrounding environment. Context-aware applications promise richer and easier interaction, but the current state of research in this field is still far removed from that vision. This is due to three main problems: (1) the notion of context is still ill defined; (2) there is a lack of conceptual models and methods to help drive the design of context-aware applications; and (3) no tools are available to jump-start the development of context-aware applications. In this paper, we address these three problems in turn. We first define context, identify categories of contextual information, and characterize context-aware application behavior. Though the full impact of context-aware computing requires understanding very subtle and high-level notions of context, we are focusing our efforts on the pieces of context that can be inferred automatically from sensors in a physical environment. We then present a conceptual framework that separates the acquisition and representation of context from the delivery and reaction to context by a contextaware application. We have built a toolkit, the Context Toolkit, that instantiates this conceptual framework and supports the rapid development of a rich space of context-aware applications. We illustrate the usefulness of the conceptual framework by describing a number of contextaware applications that h...

Context-enabled applications are just emerging and promise richer interaction by taking environmental context into account. However, they are difficult to build due to their distributed nature and the use of unconventional sensors. The concepts of toolkits and widget libraries in graphical user interfaces has been tremendously successtil, allowing programmers to leverage off existing building blocks to build interactive systems more easily. We introduce the concept of context widgets that mediate between the environment and the application in the same way graphical widgets mediate between the user and the application. We illustrate the concept of context widgets with the beginnings of a widget library we have developed for sensing presence, identity and activity of people and things. We assess the success of our approach with two example context-enabled applications we have built and an existing application to which we have added contextsensing capabilities.

Recognizing the context of use is important in making mobile devices as simple to use as possible. Finding out what the user's situation is can help the device and underlying service in providing an adaptive and personalized user interface. The device can infer parts of the context of the user from sensor data: the mobile device can include sensors for acceleration, noise level, luminosity, humidity, etc. In this paper we consider context recognition by unsupervised segmentation of time series produced by sensors. Dynamic programming can be used to find segments that minimize the intra-segment variances. While this method produces optimal solutions, it is too slow for long sequences of data. We present and analyze randomized variations of the algorithm. One of them, Global Iterative Replacement or GIR, gives approximately optimal results in a fraction of the time required by dynamic programming. We demonstrate the use of time series segmentation in context recognition for mobile phone applications. 1

Abstract. This paper presents the objectives and progress of the Context-aware Mobile Assistant Project (C-MAP). The C-MAP is an attempt to build a personal mobile assistant that provides visitors touring exhibi-tions with information based on their locations and individual interests. We have prototyped the rst version of the mobile assistant and used an open house exhibition held by our research laboratory for a testbed. A personal guide agent with a life-like animated character on a mobile computer guides users using exhibition maps which are personalized de-pending on their physical and mental contexts. This paper also describes services for facilitating new encounters and information sharing among visitors and exhibitors who have shared interests during/after the exhi-bition tours. 1

This paper introduces Gulliver’s Genie a context-aware tourist guide that assists roaming tourists. The approach adopted within this system is the deployment of intelligent agents, which collectively determine the user context and retrieve and assemble multi-media presentations that are wirelessly transmitted and displayed on a Personal Digital Assistant (PDA). As a backdrop, we first consider the state of the art in terms of context sensitive tourist guides, telecommunications, positioning technology and agent technologies. Gulliver’s Genie considers user context in terms of position, orientation and user profile. System agents are strong intentional agents that base deductions on a mental state comprising of Beliefs, Desires and Intentions (BDI). This paper presents the design of the system together with a glimpse of the user experience.

This paper describes a personal agent that guides a visitor through a virtual space by using context, i.e., visitor interaction, in the real world. #Context-aware# guidance in the real world has become an increasingly important research demand since the advent of small and powerful palmtop computers, or PDAs (Personal Digital Assistants), that can obtain useful information about objects in the real world based on context (e.g., current location and visit history) in the real world. We have tried to extend this context-aware guidance into a virtual environment by using context not from the virtual environment but from the real world; such seamless guidance allows visitors to concentrate their attention on the understanding of actual elements. This paper reports our experiment on seamless guidance by a personal agent in a virtual ancient village using real-world context. This was presented at an open house exhibition in our research laboratories. 1 Introduction We have proposed a notion...

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User interfaces must adapt to the growing dissemination of computing power in our everyday environment. Computing devices and applications are now used beyond the desktop, in diverse environments, and this trend is accelerating. By taking context into account, context-aware applications promise richer and easier interaction. However, designers face three major obstacles: (1) the notion of context is still ill-defined; (2) there is a lack of conceptual models and methods to help drive the design of context-aware applications; and (3) no tools are available to jump-start the development of context-aware applications. In this paper, we address these three problems in turn. We first define context, identify categories of contextual information, and characterize context-aware application behavior. We then present a conceptual model of contextaware applications development. This conceptual model introduces abstractions to help deal with context and are implemented in a context toolkit we have built. We propose design rules that help derive relevant context components from the application requirements to build the software architecture of the application. We illustrate our concepts and design rules with a prototype application we have built, a mobile context-aware conference assistant. This example application emphasizes how the abstractions we propose facilitate the description and design of a seemingly complex system. Finally, based on our experience with context-awareness, we outline future challenges for context-aware applications.

As intelligent environments become more focused on supporting human activity, we see a growing need for the computer to ascertain users' location and activity, be it for face detection, gesture recognition, or even simple tracking. To support such applications, a robust tracking algorithm is required. A camera tracking algorithm for a pan and tilt camera is proposed, that is robust to moderately dynamic backgrounds and varying lighting conditions, while requiring only modest computational resources. The algorithm is based on pre-filtering as well as temporal differencing, and achieves impressive results in the real-world setting of a university classroom.

User interfaces must adapt to the growing dissemination of computing power in our everyday environment. Computing devices and applications are now used beyond the desktop. Mobile, wearable, and pervasive computing allow users to integrate computing in the flow of their activities in the physical world. But most of our systems are still deaf and blind to anything that isn't explicitly input by the user. By taking the environmental interaction context into account, context-awareness promises easier interaction and new possibilities for applications. On the surface, there are many similarities between the needs of multimodal and context-aware applications. What can we learn from multimodality to build context-aware systems? What are the common research problems? To investigate these issues, we give a brief overview of context-aware systems, including a simple classification. We describe some abstractions we have found useful to help build context-aware applications. We then turn to the main problems facing the developers of context-aware systems and relate them to issues encountered in multimodal systems development.