Luis Yoichi Morales Saiki Satoru Satake Takayuki Kanda Norihiro Hagita Modeling environments from a route perspective. 441-448 2011 HRI http://doi.acm.org/10.1145/1957656.1957815 conf/hri/2011 db/conf/hri/hri2011.html#SaikiSKH11