Long Thanh Ngo Long The Pham Phuong Hoang Nguyen Kaoru Hirota Extending Fuzzy Directional Relationship and Applying for Mobile Robot Collision Avoidance Behavior. 444-450 2006 10 JACIII 4 http://www.fujipress.jp/finder/xslt.php?mode=present&inputfile=JACII001000040001.xml db/journals/jaciii/jaciii10.html#NgoPNH06