[1] Natl Def Acad Japan, Dept Comp Sci, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 2398686, Japan
[2] Shibaura Inst Technol, Coll Engn, Dept Elect Engn, Koto Ku, 3-7-5 Toyosu, Tokyo 1358548, Japan
[3] Univ Tsukuba, Grad Sch Syst & Informat Engn, Dept Intelligent Interact Technol, 1-1-1 Tennodai, Tsukuba, Ibaraki 3058573, Japan
[4] Utsunomiya Univ, Grad Sch Engn, Dept Mech Syst Engn, 7-1-2 Yoto, Utsunomiya, Tochigi 3218585, Japan