1. Mitsubishi Electric Co., Ltd., Information Technology R&D Center, 5-1-1 Ofuna, Kamakura 247-8501, Japan
2. Department of Precision Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
3. Research into Artifacts, Center for Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan