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Arnim Henze
04-08-1997, 03:19 AM
Dear list members,

since about one year ago besides other simulation software we have
the simulation system DADS in our institute. We increasingly use it
for different kinds of projects - direct and inverse dynamics.

Now, I wonder whether we are the only ones, that have problems using
DADS for invers dynamics:

DADS uses as input data only the positions and orientations of the
segments w.r. to time and calculates the 1st. and 2nd. derivatives
itself. The problem is, that all input data are interpolated with
cubic splines. The 2nd. derivative of these splines are straight
lines from time-step to time-step. These zig-zag 2nd. derivatives
lead to zig-zag forces and torques calculated by DADS. DADS's results
strongly oscillate around those calculated by other simulation software
or 'handmade inverse dynamics'.

To those of you, who do inverse dynamics with DADS: Do you also
have this problem and if so, how do you work around it without
too much effort?

Or - having DADS - do you use other tools to do inverse dynamics?

Thanks in advance for any information,

Arnim Henze.

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Arnim Henze
Institut f\"ur
Astronomie und Astrophysik
- Abteilung Biomechanik - email: henze@tat.physik.uni-tuebingen.de
Auf der Morgenstelle 10 Tel.: 07071-29 78654
D-72076 T\"ubingen Fax : 07071-29 5889
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