Systematic touch scheme for a humanoid robot to grasp a door knob

This paper deals with the practical problem as to how a humanoid robot opens a door in an office environment. Among the several tasks for the door opening, we focus on the recognition of a door and grasping its knob and propose a systematic touch scheme that combines the visual and touch data to grasp a knob safely and robustly. The visual recognition of a door and its knob is done by feature matching by a feature classifier and a segmentation method with minor assumptions about a knob, respectively. The position of a knob from the visual recognition is refined by the proposed touch scheme where a robot touches a knob several times with a hand equipped with a force-torque sensor. We realize that in the on-line experiment, a robot recognizes a door and its knob, and grasps the knob and partially opens the door.