Robotic nonprehensile catching: Initial experiments

This paper reports on our initial efforts to achieve robotic nonprehensile catching. First, we show the importance of nonprehensile catching in a robotic catching task. Robotic nonprehensile catching can be achieved by caging or partial caging with gravity. Since an object is restricted within a bounded region via nonprehensile catching, accurate finger positioning is not required because the robotic hand should be moved to an appropriate region where caging is achieved. Second, control strategies for nonprehensile catching are proposed. The robotic arm motion is generated on-line by using visual sensory feedback in response to the object motion. Noting that the object passes from the outside to the inside of the workspace of the robotic arm, the motion phases of which are divided into tracking and catching based on the specified region in a 3-D space. Finally, the validity of the resulting methods is demonstrated by experiments.