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View Full Version : Quaternions vs. Euler angles



Dr. Chris Kirtley
04-23-2001, 04:12 AM
Dear all,

The other day I finished off my Human Locomotion class by looking at
computer animation of walking. I pointed out to the students that in
this field, quaternions, rather than Euler angles, are preferred for
representing angular rotations. The reason for this is (I think) because
they are sequence independent, do not suffer from gymbla lock, are
relatively insensitive to round-off errors, and are pure rotation
matrices (they do not distort the animation with shear or stretch etc.).

In other words, compared to "Evil" Euler angles, they seem to be
ideal!...
http://web2.iadfw.net/sjbaker1/eulers_are_evil.html

I wonder if you agree with my conclusion (I confess that 3D has never
been my strong point!) and if so, why quaternions (which are also used
in robotics, where they form the basis of Denavitt-Hartenberg notation)
are not used more extensively in biomechanics?

Chris
--
Dr. Chris Kirtley MD PhD
Associate Professor
HomeCare Technologies for the 21st Century (Whitaker Foundation)
NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation
Dept. of Biomedical Engineering, Pangborn 105B
Catholic University of America
620 Michigan Ave NE
Washington, DC 20064
Tel. 202-319-6247, fax 202-319-4287
Email: kirtley@cua.edu
http://engineering.cua.edu/biomedical

Clinical Gait Analysis: http://guardian.curtin.edu.au/cga
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