1. Department
of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2. Fuji Electric Co., Ltd., 1
Fujimachi, Hino-shi, Tokyo 191-8502, Japan
3. ICube
Laboratory, UMR 7357 CNRS-University of Strasbourg, F-67412 Illkirch, France