Towards System Software for Physical Space ... - Semantic Scholar

Towards System Software for Physical Space Applications Kaori Fujinami

Tatsuo Nakajima

Department of Computer Science, School of Science and Engineering, Waseda University 3-4-1 Ohkubo, Shinjuku, Tokyo, Japan {fujinami, tatsuo}@dcl.info.waseda.ac.jp

ABSTRACT In ubiquitous computing era, the notion of context-awareness will play an important role. An application should be aware of its operating context for supporting and enriching human activities. Such contextual information is required to be captured as seamlessly as possible through interaction between users and surrounding environments. This leads to the need for dealing with a wide variety of contextual information from a physical world. In this paper, we propose a conceptual framework, Bazaar, for modeling the physical world and for manipulating the model. It constructs the model with self-descriptive objects represented as a set of triples. Also, a programming model allows a developer to intuitively manipulate the model and develop an application. Moreover, we report experiences with building sample applications.

Categories and Subject Descriptors C.3 [Special-purpose and application-based systems]: Real-time and embedded systems; D.2.11 [Software Architectures]: Data abstraction

General Terms Design, experimentation, human factors

1.

INTRODUCTION

The advancement of technologies, such as wireless communication technologies and high performance downsized computation, allows intelligence to be spontaneously embedded into everyday living spaces and to be connected to networks. Such a computing environment is often referred to as a ubiquitous computing environment[18], and has been investigated since early 1990’s. The notion of context-awareness will play an important role and one of the exciting research topics in ubiquitous computing era[4, 16, 17]. A system that is aware of its operating situation, i.e. context, can adapt its behavior to a user.

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This can be considered to make two major contributions to our everyday lives. One is assisting us by extracting relevant information from flooding of information. The other is enriching our daily living with value added services. Contextual information should be captured as implicitly as possible through interaction between users and surrounding environments. This leads to the needs for handling a wide variety of contextual information from a physical world, e.g. the existence at particular location[8], co-locating[1], state-of-use of everyday object[7], and so on. If collected information is more likely to the real situation and an appropriate interpretation facility is provided, we will feel less burdensome because a system can act autonomously based on what we might perceive. Applications in a physical space can often consume the same kind of contextual information. Therefore, it should be managed apart from an application itself and shared with others being supported by an infrastructure, which is often called a world model [8][14]. In this paper, we propose a conceptual framework, Bazaar, for representing physical world and manipulating the model. The model is constructed with self-descriptive objects that are represented as a set of triples. Such objects will build the model flexibly because unified specifications are less required than rigid object-oriented modeling. Also, a programming model has been provided that allows a developer to intuitively manipulate the model and develop an application. We also report experiences with building sample applications in two cases: with and without Bazaar. The contributions of this paper are as follows: 1) it provides requirements for a system software in a distributed context-aware space through development of less support, 2) it describes a method to build a world model flexibly using RDF, 3) it proposes APIs to manipulate the model intuitively, and 4) it finally shows applications of daily object coordination on top of proposed framework. The structure of this paper is as follows. In Section 2, an experience will be reported. Based on this, requirements for a system software that manages world model and provides an application developer with high level of abstraction will be introduced. Section 3 will examine related work. Section 4 will propose system software called Bazaar, where two key design points and their issues will be presented. Current status will be discussed in Section 5, where both implementation of Bazaar itself and the same example as described in Section 2 will be presented. Another example will also be presented in addition to experiences and issues raised during the development are discussed. Section 6 will show future directions and finally, Section 7 will conclude the paper.

2.

EXPERIENCE THROUGH APPLICATION DEVELOPMENT

In this section, we point out importance of and requirements for system software through simple application development.

2.1

Application: Personal Workspace

We have developed an application called personal workspace which is aware of presence of a person. Based on the awareness, it changes its behavior. Figure 1 shows the experimental environment, where the left(a) is for physical configurations, and the right(b) is for an architecture. The application simply turns on and off the stand light based on person’s presence. Given that a person does not have a radio frequency identifier system(RFID) tag, therefore person’s presence cannot be detected directly. Instead, two sensor augmented everyday artifacts provide their awareness of his/her presence, which is integrated to improve reliability of the information. We call such intelligent artifact as sentient artifacts, and we have developed three ones: SentientCradle (Figure 1-(a)-(i)), SentientLight (Figure 1-(a)-(ii)), and SentientChair (Figure 1-(a)-(iv)). We consider that every daily object has a functionality and, therefore, its state-ofuse contributes to reduce uncertainty of inferred context. In case of both SentientCradle and SentientChair are detected, information from both is aggregated(OR operation): if none of them is indicating someone is there, the light is turned off. On the other hand, only one of them is detected or available, it is utilized individually. SetientCradle is a cellular phone cradle that is aware of three kinds of information: 1) the existence of the cellular phone on the cradle, 2) number of call received until it is reset, and 3) the state, i.e. resetting or not. When a call is received, the cradle moves its legs based on the number of calls to notify its owner of the call. It utilizes two types of sensor connected to Phidget Interface Kit1 . Engineering details can be seen in [19]. Next, SentientChair is a sensor augmented chair that is aware of its states of use, i.e. someone is sitting or not. It has three force sensors and one photo sensor as can be seen in Figure 1-(a)-(iv). This is also built using Phidget sensors. Finally, we have also augmented an ordinal stand light, SentientLight. It senses environmental light-level using Phidget photo sensor in addition to its primary taks of brightening surroundings, and can be controlled via X10 light module. As in Figure 1-(b), each sentient artifacts is connected to a laptop individually for extracting context and controlling itself via USB or RS-232C, and they communicate with central server hosting the application by HTTP over wireless LAN connection. SentientLight has HTTP server on it and can be controlled through this HTTP-based messaging facility. In the future, a laptop can be replaced to an embedded computer. In the experimental setting, RFCode Inc.’s Spider RF-tag reader is used as location sensing system and the only one that is fixed in location, while the other sentient artifacts with RF-tags are movable and determined at runtime.

2.2

Lessons learned

Here, we list lessons through the development and requests for system support. 1

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