1. Graduate School EngineeringHirohisma University 1‐4‐1 Kagamiyama, Higashi‐Hiroshima Hiroshima 739‐8527 Japan
2. Institute of EngineeringHiroshima University 1‐4‐1 Kagamiyama, Higashi‐Hiroshima Hiroshima 739‐8527 Japan
3. Department of Intelligent Mechanical SystemsKumamoto University 2‐39‐1 Kurokama, Chuo‐ku Kumamoto 860‐8555 Japan