Compliant Grasping Using Self-Sealing Suction Cup Arrays
J. P. Desai, C. C. Kessens
This work is sponsored in part by the U.S. Army Research Laboratory.
Biologically-Inspired Robots; Grasping; Mechanism Design of Manipulators; Mobile Manipulation; Motion Control of Manipulators; Compliance
General use graspers must be designed to perform unknown missions in unknown environments. For autonomous or semi-autonomous operations, many missions require robustness against errors in manipulator placement and incomplete object information. The speed with which grasping can be performed is another critical factor in grasping performance, a limitation of current complex anthropomorphic graspers. This research attempts to exploit the advantages of controllable compliance for rapidly grasping a wide range of unmodeled object geometries.
The objectives of this project are:
1. Integration of astrictive technologies to grasping. Astrictive technologies have the potential to provide significant additional capability to grasping, including increased range of object size and geometry as well as increased stability. The grasper should effectively use this technology to demonstrate its full potential for grasping solutions.
2. Development of a conformable grasper. The grasper should emphasize functional simplicity while demonstrating robustness to positioning errors from inaccurate sensing and/or inaccurate end effector placement. It should also be able to quickly grasp objects of unknown shapes.
Overview of Approach
Development of self-sealing suction cup arrays: Suction has been shown to be useful for grasping a wide range of object sizes and geometries. However, current applications are designed for one specific object size and geometry. The ability to utilize this powerful concept of suction on a single grasper for manipulating objects with widely varying shapes and sizes has the potential to expand a robot’s object manipulation capability. This capability expansion will be important as robots continue to move into human environments with less predictability and more demands. Our approach is to design, fabricate, and test a concept for a “self-selecting” suction cup array. When the suction cup encounters an object, it opens to allow suction on that object. However, if the cup is not in contact with an object, the cup remains sealed, minimizing leakage through the unengaged cup and maximizing the suction force of the cups that are engaged on the object. Thus, a large number of suction cups could be placed on the manipulator, but it could still pick up small objects. Further, “sensing” and “actuation” of the valves are controlled by the object’s passive reaction forces, minimizing computational requirements and often heavy hardware. Ultimately, the goal of this research is to expand the usefulness of this suction technology to manipulate objects with a wide range of shapes and sizes using a single manipulator.
Development of a conformable grasper: Current grasping techniques are often either so crude that they are limited in the objects that they can grasp, or so complex that they require intricate object modeling and grasp planning. A conformable grasper that is able to mold itself to the shape of the object to be manipulated offers the potential for increased versatility without increased complexity. In addition, such a grasper would have continuous contact with the object, distributing loads and providing improved grasp stability.
Chad C. Kessens and Jaydev P. Desai, “Design, Fabrication, and Implementation of a Self-Sealing Suction Cup Array for Grasping,” IEEE International Conference on Robotics and Automation, Alaska, USA, May 2010.
Prof. Jaydev P. Desai
Director—Robotics, Automation, and Medical Systems Laboratory
Department of Mechanical Engineering
0160 Glenn L. Martin Hall
University of Maryland College Park, MD 20742
Email: jaydev (at) umd.edu
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