simtk.org

Hi,
I am completely new in OpenSim. I have a big problem with scaling. After I run the scale tool I get this result. The markers are apart from the model! Any idea? The errors are too big. I did the scaling with other openSim model and the result was great but with this one I got this strange result.

Hi,

This model does not have translation degrees of freedom (DOFS) in the z axis. It is possible that the static pose is positioned in such a way that the model is not able to achieve given its DOFS. You can either change the pelvis DOFS or use the gait2364 model.

Hi,
Thanks for your help. you are right. I try to change the DoF of Pelvis. I change the XML file. is it OK? it seems it works correctly. But I am not sure if I change all the required code? How can I test it? Do you know where can I find a tutorial or document?

This is the best place to start:

https://simtk-confluence.stanford.edu:8 ... %27s+Guide

thanks

Hi!
I have some problems with model scaling too. We are shooting data by Qualisys, the model in QTM looks normal, and there are no problems with the trajectories of markers. But when I load data in OpenSim, the model distorts along with the markers. It happens only on some surveys, I can not understand the reason, we do everything the same, but for some reason sometimes everything is all right, and sometimes such problems appear. What can you advise me to correct this situation?

Thank you

Hi! Did you try to import the trc data with the preview into opensim? Seems that experimental data orientation axis is different than the model axis.

Andrea

HI, Evgeniya-

there are no problems with the trajectories of markers.

From the images you sent, it looks like there could be mislabelled markers- you should double check that all the markers are labeled correctly.

Hi,
I have some problems with scaling also. I collect data with Qualisys and everything looks fine in there. When I load data in OpenSim markers and forces looks just fine (static.png). Uploaded model looks fine also (I use slightly modified to my marker set TwoLegsHATArnoldetalv2.1 - modeluploaded.png). When I try to scale the model it turns in pelvis somehow (scaledmodel.png).
I have this problem with only one patient. Every marker is correctly named. When I preview experimental data (only markers and forces) it goes normally. After scaling model and applying IK it is side walking... I did everything according to github instruction.

Could you tell me what can I do with this?
I want to calculate muscle-tendon length during walking.

Thank you

Hi Urszula,

The issue your seeing could be one of several possibilities. Have you checked that there are no missing or occluded markers for that subject/trial? That could cause issues even if the markers are labeled correctly.

In general, I highly recommend checking out https://addbiomechanics.org/, a new web-based tool for automating the scaling process.

Best,
Nick