Last March, roboticist Eric Brown and co-workers at the University of Chicago made headlines with their new, unconventional robot gripper design: a balloon filled with coffee grounds or other grainy material and fitted with a vacuum line. At atmospheric pressure, the balloon is squishy and can be “mushed” around an object—even traditionally hard-to-grip stuff like thin flat bars and spheres—but suck the air out of the balloon, and it tightens down around the grains, “jamming” them into a rigid state and gripping the object securely. The process is fully reversible, too: open a valve to restore atmospheric pressure inside the balloon, the gripper reverts to its “mushy” state, and the object is released.

Jamming "coffee balloon" gripper in grabbing (left) and "shooting" modes.

Now the original team from Chicago, in collaboration with Cornell’s John Amend and Hod Lipson, have figured out how to go one better. Instead of just releasing the vacuum to release the object, they can apply sudden positive pressure inside the balloon to violently expel/shoot/pop/throw the object away from the gripper. The embedded video shows off the trick nicely, and is, incidentally, lots of fun. [via adafruit]

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