This article describes a new class of end-effectors that can be used with robotic and material handling devices for grabbing and holding deformable objects with undefined shapes such as sacks and bags. These end-effectors can grab and hold filled sacks from any point on the sack and regardless of the sack orientation and position. The first prototype end-effector, designed for the U.S. Postal Service, has two rollers. The rollers are pushed toward each other by the force of a spring. When the rollers are powered to spin, the inward spinning of the rollers causes the sack material to be dragged in between the rollers due to the friction between the surfaces of the rollers and the sack material. The spring pushes the rollers toward each other with sufficient force to hold the sack material in place between the rollers. The end-effector described here has been evaluated and proven to be exceedingly effective in grabbing and holding postal sacks. This article describes the underlying principles of the design, grasp conditions and control of the end-effector.

Issue Section:
Technical Papers
Keywords:
end effectors, materials handling equipment, materials handling, position control, postal services
Topics:
End effectors, Rollers, Robotics, Friction
1.
Son, J. S., Howe, R. D., Wang, J., and Hager, G. D., “Preliminary Results on Grasping with Vision and Touch,” Proceedings of IROS ’96: IEEE/RSJ International Conference on Intelligent Robots and Systems, Osaka, Japan, Nov. 4–8, 1996.
2.
Howe
,
R. D.
, and
Cutkosky
,
M. R.
, December 1996, “Practical Force-Motion Models for Sliding Manipulation,” Int. J. Robot. Res., 15(6).
3.
Howe
,
R. D.
, and
Cutkosky
,
M. R.
, April
1993
, “
Dynamic Tactile Sensing: Perception of Fine Surface Features with Stress Rate Sensing
,”
IEEE Trans. Rob. Autom.
,
9
(
2
),
140
–
151
.
4.
Okamura, A., Turner, M., and Cutkosky, M., “Haptic Exploration of Objects with Rolling and Sliding Contacts,” Proceedings of the 1998 IEEE International Conference on Robotics and Automation, Vol. 3, pp. 2485–2490.
5.
Bicchi, A., Salisbury, J. K., and Dario, P., “Augmentation of Grasp Robustness Using Intrinsic Tactile Sensing,” Proc. of IEEE Int. Conf. On Robotics and Automation, pp. 302–307, 1989.
6.
Rosheim
,
M.
,
1983
, “
The 2-Roll Gripper
,”
The Journal of Intelligent Machines
, Feb.
83
,
32
–
38
.
7.
Jacobsen, S. C., Iversen, I. K., Knutti, D., Johnson, R. T., and Biggers, K. B., “Design of the Utah/MIT Dextrous Hand,” Proceedings IEEE Int. Conf. on Robotics and Automation, USA, 1986, pp. 1520–1532.
8.
Salisbury, J. K., “Design and Control of an Articulated Hand,” Int. Symposium on Design and Synthesis, Tokyo, 1984.
9.
Mason, T. M., (1985), “Manipulator Pushing and Grasping Operations,” in “Robot Hands and the Mechanics of Manipulation,” P. H. Winston and J. M. Brady Edt., The MIT Press Series in Artificial Intelligence, ISBN 0-62-13205-2
10.
Jau, B. M., Man-Equivalent Telepresence Through, Four Fingered Human-Like Hand System, Proc. IEEE Conf. on Robotics and Automation, France, 1992, pp. 843–848.
11.
Maeda, Y., Tachi, S., and Fujikawa, A., Development of an Anthropomorphic Hand (Mark-1), Proc. Int. Symp. on Industrial Robots, Tokyo, 1989, pp. 537–544.
12.
Sugano, S., and Kato, I., Wabot-2: Autonomous Robot with Dextrous Finger-Arm Coordination in Keyboard Performance, Proc. IEEE Conf. on Robotics and Automation, Raleigh, 1987.
13.
Hashimoto, H., Ogawa, H., Obaman, M., Umeda, T., Tatuno, K., and Kurukawa, T., Development of a Multi-Fingered Robot Hand with Fingertip Tactile Sensors, Proc. IEEE Conf. on Intelligent Robots and Systems, Yokohama, 1993, pp. 875–882.
14.
Bicchi
,
A.
,
Salisbury
,
J. K.
, and
Brock
,
D. L.
,
1993
, “
Contact Sensing from Force Measurements
,”
Int. J. Robot. Res.
,
12
(
3
), pp.
249
–
262
.
15.
Fearing
,
R. S.
,
1990
, “
Tactile Sensing Mechanisms.
”
Int. J. Robot. Res.
,
9
(
3
),
3
–
23
.
16.
Fearing
,
R. S.
,
1986
, “
Simplified Grasping and Manipulation with Dextrous Robot Hands.
”
IEEE Trans. Rob. Autom.
,
4
(
2
),
188
–
195
.
17.
Goldberg
,
K. Y.
,
1993
, “
Orienting Polygonal Parts without Sensors.
”
Algorithmica
,
10
(
2
),
201
–
225
.
18.
Kerr
,
J. R.
, and
Roth
,
B.
, 1986, “Analysis of Multi-Fingered Hands.” Int. J. Robot. Res., 4(4).
19.
Mason
,
M. T.
,
1986
, “
Mechanics and Planning of Manipulator Pushing Operations.
”
Int. J. Robot. Res.
,
5
(
3
),
53
–
71
.
20.
Mishra
,
B.
, and
Silver
,
N.
,
1989
, “
Some Discussion of Static Gripping and Its Stability.
”
IEEE Trans. Syst. Man Cybern.
,
19
(
4
),
783
–
796
.
21.
Nguyen
,
V.-D.
,
1988
, “
Constructing Force-Closure Grasps.
”
Int. J. Robot. Res.
,
7
(
3
),
3
–
16
.
22.
Nguyen
,
V.-D.
,
1989
, “
Constructing Stable Grasps.
”
Int. J. Robot. Res.
,
8
(
1
),
27
–
37
.
23.
Ferrari, C., and Canny, J. F., (1992), “Planning Optimal Grasps.” In Proc. IEEE Int. Conf. on Robotics and Automation, Nice, France, pp. 2290–2295.
24.
Goldberg, K., and Mason, M. T., (1990), “Bayesian Frasping.” In Proc. IEEE Int. Conf. on Robotics and Automation, IEEE Press, pp. 1264–1269.
25.
Pollard, N. S., and Lozano-Perez, T., (1990), “Grasp Stability and Feasibility for an Arm with an Articulated Hand.” In Proc. IEEE Int. Conf. on Robotics and Automation, IEEE Press, pp. 1581–1585.
26.
Ponce
,
J.
, and
Faverjon
,
B.
,
1995
, “
On Computing Three-Finger Force-Closure Grasps of Polygonal Objects.
”
IEEE Trans. Rob. Autom.
,
11
(
6
),
868
–
881
.
27.
Ponce
,
J.
,
Stam
,
D.
, and
Faverjon
,
B.
,
1993
, “
On Computing Force-Closure Grasps of Curved Two-Dimensional Objects.
”
Int. J. Robot. Res.
,
12
(
3
),
263
–
273
.
Copyright © 2004
 by ASME
You do not currently have access to this content.