The singularities of manipulators with offset wrists are difficult to enumerate. This article presents a numerical study to illuminate singularity problems when using an offset wrist with an articulated regional arm. Ironically, the regional manipulator singularity problem is worsened when using a singularity-free offset wrist. No wrist singularities exist (they are forced by design to lie outside of joint limits). However, the existing regional arm singularities become skewed from the well-known singular configurations of common manipulators. The wrist offset also skews the well-known wrist singularities (though they hopefully still lie outside of joint limits, their locations are no longer easily determined). Thus, a zero-offset singularity-free wrist is preferable with regard to overall manipulator singularities.

1.
Burdick
J. W.
,
1995
, “
A Recursive Method for Finding Revolute-Jointed Manipulator Singularities
,”
ASME JOURNAL OF MECHANICAL DESIGN
, Vol.
117
, pp.
55
63
.
2.
Craig, J. J., 1989, Introduction to Robotics: Mechanics and Control, Addison Wesley Publishing Co., Reading, MA.
3.
Kholi
D.
, and
Hsu
M. S.
,
1987
, “
Boundary Surfaces and Accessibility Regions for Regional Structures of Manipulators
,”
Mechanism and Machine Theory
, Vol.
22
, No.
3
, pp.
277
289
.
4.
Lee
K. M.
,
Roth
R. B.
, and
Zhou
Z.
,
1996
, “
Dynamic Modeling and Control of a Ball-joint-Like Variable Reluctance Spherical Motor
,”
Journal of Dynamic Systems, Measurement, and Control
, Vol.
118
, No.
1
, pp.
29
40
.
5.
Milenkovic, V., 1987, “New Nonsingular Robot Wrist Design,” Robots II Conference Proceedings RI/SME, Chicago, IL, pp. 13.29–13.42.
6.
Rosheim, M. E., 1987, “Singularity-Free Hollow Spray Painting Wrists,” Robots II Conference Proceedings RI/SME, Chicago, IL, pp. 13.7–13.28.
7.
Stanisic, M. M., and Duta, O., 1990, “Symmetrically Actuated Double Pointing Systems: The Basis of Singularity-Free Robot Wrists,” IEEE Transactions on Robotics and Automation, Vol. 6, No. 5.
8.
Sugimoto
K.
,
Duffy
J.
, and
Hunt
K. H.
,
1982
, “
Special Configurations of Spatial Mechanisms and Robot Arms
,”
Mechanism and Machine Theory
, Vol.
17
, No.
2
, pp.
119
132
.
9.
Trevelyan
J. P.
,
Kovesi
P. D.
,
Ong
M.
, and
Elford
D.
,
1986
, “
ET: A Wrist Mechanism Without Singular Positions
,”
The International Journal of Robotics Research
, Vol.
4
, No.
4
, pp.
71
85
.
10.
Waldron
K. J.
,
Wang
S. L.
, and
Bolin
S. J.
,
1985
, “
A Study of the Jacobian Matrix of Serial Manipulators
,”
Journal of Mechanisms, Transmissions, and Automation in Design
, Vol.
107
, pp.
230
238
.
11.
Williams, R. L. II, 1990, “Forward and Inverse Kinematics of Double Universal Joint Robot Wrists,” Proceedings of the 1990 Space Operations, Applications, and Research (SOAR) Symposium, Albuquerque, NM.
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