Universal robotic gripper based on the jamming of granular material — PNAS

Universal robotic gripper based on the jamming of granular material

1. Eric Browna,1,
2. Nicholas Rodenberga,
3. John Amendb,
4. Annan Mozeikac,
5. Erik Steltzc,
6. Mitchell R. Zakind,
7. Hod Lipsonb, and
8. Heinrich M. Jaegera

+ Author Affiliations

1. aJames Franck Institute and Department of Physics, University of Chicago, Chicago, IL 60637;
2. bSchool of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853;
3. ciRobot G and I Research, 8 Crosby Drive, Bedford, MA 01730; and
4. dDefense Advanced Research Projects Agency, 3701 North Fairfax Drive, Arlington, VA 22203

1. Edited by Daniel Meiron, Cal Tech, and accepted by the Editorial Board September 17, 2010 (received for review March 16, 2010)

Abstract

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 advance opens up new possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of complex objects.

* stress-strain
* packing density
* friction
* suction
* interlocking

Footnotes

* 1To whom correspondence should be addressed. E-mail: embrown@uchicago.edu.
* Author contributions: E.B., J.A., A.M., E.S., M.R.Z., H.L., and H.M.J. designed research; E.B., N.R., J.A., A.M., and E.S. performed research; E.B., N.R., J.A., A.M., E.S., H.L., and H.M.J. analyzed data; and E.B., J.A., and H.M.J. wrote the paper.
* Conflict of interest statement: E.B., J.A., H.L., H.M.J., and iRobot Corporation have filed patent applications on related technology.
* This article is a PNAS Direct Submission. D.M. is a guest editor invited by the Editorial Board.
* This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1003250107/-/DCSupplemental.
* *In our gripper the molding of the bag around the test sphere resulted in thinning near the opening, such that t decreased roughly linearly with θ. The effect of such thinning is that Fi levels off at a somewhat lower value and at θ < π. To model the thinning, we can take t ≈ 2R(π - θ)/π.

Universal robotic gripper based on the jamming of granular material — PNAS



BIOMEDICINA
Desarrollan una mano artificial más precisa para agarrar objetos
Actualidad Ultimas noticias - JANOes -
JANO.es · 26 Octubre 2010 09:36

El dispositivo podría superar a los dedos robóticos ante elementos no familiares o con formas complejas.


Investigadores de la Universidad de Chicago en Estados Unidos han desarrollado un 'agarrador universal' robótico que utiliza una bolsa de goma llena de partículas para recoger objetos cotidianos. Las conclusiones de su trabajo se hacen públicas esta semana en la edición digital de la revista Proceedings of the National Academy of Sciences (PNAS).

Los científicos, dirigidos por Eric Brown, desarrollaron y probaron el agarrador, que se amolda alrededor de objetos duros como lo hacen las pequeñas bolsas con relleno y se contrae y endurece cuando se aplica un vacío débil. El diseño elimina la necesidad de una retroalimentación visual compleja y de los sistemas de detección de fuerza que son necesarios para los dedos robóticos y permite al dispositivo cambiar entre objetos de diferente forma y fragilidad como bombillas, caramelos, tapones de los oídos o cáscaras de huevo.

La versatilidad del agarrador se deriva de la conducta del material granular interno de la bolsa que puede pasar de forma rápida a los estados de fluido y apretado cuando las partículas son presionadas conjuntamente bajo condición de vacío.

Aunque el concepto de un agarrador moldeable en lugar de los dedos robóticos similares a los humanos se había propuesto antes, los investigadores no comprendían el mecanismo de la transformación de suave a rígido por lo que la idea nunca había ganado atención.
Los autores sugieren que el dispositivo podría superar a los dedos robóticos cuando se trata de objetos no familiares o con formas complejas y que la construcción hermética del agarrador le convertiría en útil en ambientes húmedos o volátiles.


PNAS (2010); doi: 10.1073/pnas.1003250107
Universal robotic gripper based on the jamming of granular material — PNAS

Universidad de Chicago
The University of Chicago


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