the public service area, the basic four human intentional actions,‘approach’, ‘depart’, ‘bypass’, and ‘stop’ were investigated by
the human’s movement pattern. In order to recognize those four
human intentional actions, the mobile robot measured 360
degree distance between a robot and a human by two
IR-scanner sensors, and three problems were solved: 1) human
detection and tracking by improved K-means clustering method,
2) absolute human velocity estimation by Extended Kalman
Filter, and 3) inferring intentional actions by HMM with
position-dependent observation model.