Manipulation Capabilities with Simple Hands

A simple hand is a robotic gripper that trades off generality in function for practicality in design and control. The long-term goal of our work is to explore that tradeoff and demonstrate broad manipulation capabilities with simple hands. This paper describes two prototype simple hands. Both hands have thin cylindrical fingers arranged symmetrically around a low friction circular palm. The fingers are compliantly coupled to a single actuator. Our experiments with both hands in a bin-picking scenario demonstrate that we can achieve robust grasp classification and in-hand localization using simple statistical techniques. We further show how the classification accuracy increases as the grasp proceeds by exploiting information obtained online. We finally evaluate the relative importance of observing the full state of the hand rather than just observing the state of the actuators.