1. Department of Precision EngineeringThe University of Tokyo Hongo 7-3-1 Bunkyo-ku Tokyo 113-8656 Japan
2. Department of Mechanical and Intelligent Systems EngineeringUniversity of Electro-Communications Tokyo 182-8585 Japan
3. General Industry Products DivisionToyoda Gosei Co., Ltd. 1-1 Higashitakasuka, Futatsudera Ama Aichi 490-1207 Japan