My name is David Lim, and I am a Masters Student at Embry-Riddle Aeronautical University. I am working on a research project that aims to model an infant by scaling the Opensim GAIT 2392 model. By using marker based kinematic data recorded using motion capture cameras, we were able to scale the model and apply the motion appropriately. The issue comes when running the inverse dynamics tool, however. It seems that through the scaling, the ground becomes displaced, and the origin for the model moves from the overall origin, so the GRF placed on the ground to represent the weight of the infant during its movements is applied incorrectly, and the coordinates of the new "origin" unknown. I was unable to find any solutions of moving the ground back to the origin. I was wondering if anyone had any similar issues or has a solution to this problem.
Thank you so much in advance!
Ground Origin GRF Placement
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Thomas Uchida
- Posts: 1778
- Joined: Wed May 16, 2012 11:40 am
Re: Ground Origin GRF Placement
This may be a "model offset" issue---please see the "Model Offset" section on the "Object-Specific Commands" page in the documentation: https://simtk-confluence.stanford.edu/d ... c+Commands. You may also want to investigate whether scaling the 2392 model down to the size of an infant will produce a useful model.
Re: Ground Origin GRF Placement
Thank you so much for the reply!
In terms of the model offset function, that does help with the offset of the ground, but not of the model itself.
I tried applying the GRF to the coordinates of a marker on the scaled infant, but the coordinates of those markers are not based on the origin axis on the "ground", and I am finding it difficult to find the coordinates of the model in relation to the aforementioned origin axis found on the "ground", and therefore am unable to properly place the GRF in relation to the model. Hope this makes sense! Thank you very much!
In terms of the model offset function, that does help with the offset of the ground, but not of the model itself.
I tried applying the GRF to the coordinates of a marker on the scaled infant, but the coordinates of those markers are not based on the origin axis on the "ground", and I am finding it difficult to find the coordinates of the model in relation to the aforementioned origin axis found on the "ground", and therefore am unable to properly place the GRF in relation to the model. Hope this makes sense! Thank you very much!