Gripping a Kitchen Knife on the Cutting Board

Despite more than three decades of grasping research, many tools in our everyday life still pose a serious challenge for a robotic hand to grip. The level of dexterity for such a maneuver is surprisingly "high" that its execution may require a combination of closed loop controls and finger gaits. This paper studies the task of an anthropomorphic hand driven by a robotic arm to pick up and firmly hold a kitchen knife initially resting on the cutting board. In the first phase, the hand grasps the knife’s handle at two antipodal points and then pivots it about the knife’s point in contact with the board to leverage the latter’s support. Desired contact forces exerted by the two holding soft fingers are calculated and used for dynamic control of both the hand and the arm. In the second phase, a sequence of gaits for all the five fingers is performed quasi-statically to reach a power grasp on the knife’s handle, which remains still during the period. Simulation has been performed using models of the Shadow Hand and the UR10 Arm.