move a segment with markers

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1

hi,

I have a problem driving a segment via marker trajectory! I am just
playing around with the marker stuff in AnyBody at the moment to get
familiar with it, so I wrote my own text file to move a segment just in
one direction. I build a segment with two nodes. The nodes are
connected to the markers in the same way like in the Gait3D model but I
always get an error in time step 0….what’s wrong or what can I do??

Thanks for reply
Tom

2

Hi Tom

It difficult to tell from this description what is wrong with the model.

If you have one segment you will need to apply six drivers to it, no more no
less. If you have too many it will make the kinematics overconstrained, and
if you have less it will be undetermined.

I would recommend following these steps:

1 apply one marker driver which driver the three linear directions.

2 driver the rotations of the segment to zero

3 make sure it runs

4 remove one dof from the rotations drivers and replace it by a linear
driver from a new marker

5 continue step four until all dof is driven by markers.

It is important that you use the local coordinate system of the segment this
is the Ref=0 setting normally seen in the AnyKinLinear objects in the gait
model

Did you notice the new GaitModel of repository7? it is driven with the use
of an external application please posting #2143 for details. It makes it
easier to drive a lower extremity with maker data.

Best regards

Søren, AnyBody Support

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of kollair12345
Sent: 13 May 2008 16:21
To: anyscript@yahoogroups.com
Subject: [AnyScript] move a segment with markers

hi,

I have a problem driving a segment via marker trajectory! I am just
playing around with the marker stuff in AnyBody at the moment to get
familiar with it, so I wrote my own text file to move a segment just in
one direction. I build a segment with two nodes. The nodes are
connected to the markers in the same way like in the Gait3D model but I
always get an error in time step 0….what’s wrong or what can I do??

Thanks for reply
Tom

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