Gripping and holding of objects are key tasks for robotic manipulators. The development of universal grippers able to pick up unfamiliar objects of widely varying shape and surface properties remains, however, challenging. Most current designs are based on the multifingered hand, but this approach introduces hardware and software complexities. These include large numbers of controllable joints, the need for force sensing if objects are to be handled securely without crushing them, and the computational overhead to decide how much stress each finger should apply and where. Here we demonstrate a completely different approach to a universal gripper. Individual fingers are replaced by a single mass of granular material that, when pressed onto a target object, flows around it and conforms to its shape. Upon application of a vacuum the granular material contracts and hardens quickly to pinch and hold the object without requiring sensory feedback. We find that volume changes of less than 0.5% suffice to grip objects reliably and hold them with forces exceeding many times their weight. We show that the operating principle is the ability of granular materials to transition between an unjammed, deformable state and a jammed state with solid-like rigidity. We delineate three separate mechanisms, friction, suction, and interlocking, that contribute to the gripping force. Using a simple model we relate each of them to the mechanical strength of the jammed state. This opens up new possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of complex objects.

1. •Brown, E., Rodenberg, N., Amend, J., Mozeika, A., Steltz, E., Zakin, M., Lipson, H., Jaeger, H. (2010) "Universal robotic gripper based on the jamming of granular material," Proceedings of the National Academy of Sciences (PNAS), Vol. 107, no. 43. link to pdf file (incl. suppl. material)
   

2. •Link to more details, high-res images, FAQs, and several movies at the website of our Cornell collaborators, John Amend and Hod Lipson
   

3. •Link to list of 170+ popular press articles written about the jamming gripper (compiled by John Amend @ Cornell)
   

4. •Link to U of Chicago press release
   

5. •Link to Cornell University press release
   

Watch a gripper prototype in action at the Cornell Computational Synthesis Lab (the two movies below were made by John Amend at Cornell):

Watch another gripper prototype, made by iRobot, as demonstrated at a TEDmed 2009 event by Colin Angle, iRobot's CEO, on YouTube.

Finally, here is a link to a nice DIY gripper that you can make at home (materials list and instructions included!). This gripper was made by Carlos Asmat, an engineer in Montreal, after he watched our gripper videos (above). Click here to see Carlos' first DIY gripper in action. As of May 30, 2011, Carlos posted an elegantly improved version 2.0 of his earlier design.