1.5.  Outline of the Thesis 7 [ Antifakos et al. 2002 ] , [ Antifakos et al. 2004 ] , and [ Michahelles et al. 2003a ] illus- trate the joined work on proactive furniture assembly in cooperation with Stavros Antifakos. The sensor-opportunities-based approach was first proposed in [ Micha- helles and Schiele 2003 ] . [ Michahelles et al. 2004a ] covers the artifact-based devel- opment approach. In [ Michahelles et al. 2003b ] the development of wearable sensing for avalanche rescue was presented. In addition, [ Michahelles et al. 2004b ] describes the revised sensing concept by the use of radar for heart-rate detection.  Finally, [ Michahelles et al. 2005 ] reports on the application of wearable sensors in downhill skiing. 1.5   Outline of the Thesis In the following, the content of each chapter is briefly summarized. Chapter 2  reviews research that is relevant in the context of this thesis. First, re- quirements are formulated that should be fulfilled by an ideal development pro- cess. Secondly, the main research directions concerning software-engineering, software design, user-centered design, participatory design, and some others pertinent to this dissertation are described and evaluated with respect to these requirements. Finally, the chapter concludes with some general findings that lead to the development of the  X’treme Prototyping  approach presented in Chapter 4. Chapter 3  presents two early pilot studies and the lessons learned. This guided us towards the design of the X’treme Prototyping approach presented in Chap- ter 4. In particular it describes two projects that followed two very distinct standpoints. First, a purely technology-driven approach is illustrated by means of the development of a flat-pack furniture that can give proactive hints to the user about how to assemble it.  Secondly, the course of the development of a wearable assistant with doctors derives lessons learned from a more user- centered approach.  Both case studies are presented to lead to the  X’treme Prototyping approach presented in Chapter 4. Chapter 4  proposes an approach for research to overcome the tension between user focus and the introduction of radically new concepts and technology. It introduces the notion of X’treme Prototypes that expose users to radically new concepts and technology that they might have never thought of before. The basic promise is to free users’ minds and to stimulate them to imagine new concepts and technology in combination with changes in their current work practice.