1. Graduate School of Computer Science and Engineering, University of Aizu, Fukushima 965-0006, Japan
2. Centre of Robotics and Intelligent Systems, University of Sri Jayewardenepura, Nugegoda 10250, Sri Lanka
3. School of Social Informatics, Aoyama Gakuin University, Tokyo 150-8366, Japan
4. Graduate School of Engineering and Science, Shibaura Institute of Technology, Tokyo 135-8548, Japan