For the personal robot to serve humans as a companion in our daily life, it is obviously important that the robot should have a long-term relationship to users. In this paper, we introduce a simple idea on how to make the long-term relationship by using just low-cost and simple robots. We also describe the robotic artificial creature system to implement this idea. The artificial creature robots respond not only physical environment changes but also the logical information changes in the virtual world such as the Web. They consist of a control robot and several simple robots, which show users various group behaviors. Users have a relationship with them by observing these behaviors, rather than interacting with them. We separate physical robots and software applications in order that artificial creature robots can have more various behaviors made by various software applications. Finally, we implemented the system using a robot simulator to show some example cases.

For the pervasive computing in ubiquitous environment, it is very important to manage the context model to provide pertinent context knowledge to context-aware applications. The context model should be able to support efficiently the context knowledge reusing and sharing as well as reasoning. Previous works focus mainly on the context knowledge representation scheme for reasoning. This paper proposes a context knowledge modeling scheme especially for reusing and sharing. This scheme provides well-established principles and guides for 1) context knowledge modularization and hierarchization, and for 2) context knowledge identification and organization. Once the context models are built according to the scheme, the structure of the context model and the meanings of the context knowledge elements become clear and consistent, so that context-aware applications can share and reuse the context knowledge in easy and error-reduced manner. This paper also discusses the implementation of a context model and an application for Presentation Helper scenario running on a software middleware system (CAMUS) for ubiquitous service robots which is being developed by ETRI Korea.