Hi,
I am a new user of Opensim. I confused with some points of this software to stimulate gait.
I have a whole body model, but the coordinate of static data I collected (lab coordinate) is different from model coordinate, in fact upward is z-axis in lab coordinate but y-axis in model coordinate. I tried two ways to do the scaling and IK step, one is did not transform lab coordinate to model coordinate (but the lab coordinates of static and walking file are same), and the model after scaling and IK results are pretty good expect the object-model is transverse
compared with original model.and the scaling model walk along the z-axis (but the example of gait2354 walk along the x-axis).
the other way is I change the lab coordinate (static and walk) the same with model coordinate,but the scaling and IK result are not good, because the body is extremely distort when finish IK step.
So my question is if my other files which contained coordinates, such as ground force coordinate are all same with lab coordinate but not the original model coordinate, is that ok with the next steps (ID, RRA,CMC)
thanks a lot for who may concern this.
scaling and IK
RE: scaling and IK
Hi Hang Xu,
Before you can run the Scale & IK tools in OpenSim, it is important that you have your marker coordinates in the Model coordinate system (not the lab coordinate system). If you want to run inverse dynamics, RRA, static optimization or CMC, you also need you ground forces in the model coordinate system as well. There are several ways to do this:
1) If you have your marker (trc file) and GRF (mot file) in your lab coordinates, you can use the opensim "Preview motion data" tool to convert your data to the correct coordinate system.
2) If you have the captured data in a c3d file (i.e. Vicon), you can download and use my C3D extraction toolbox for Matlab (https://simtk.org/home/c3dtoolbox) to produce all the necessary trc and mot files (in the correct model coordinate system) for importing your experimental data into OpenSim.
Before you can run the Scale & IK tools in OpenSim, it is important that you have your marker coordinates in the Model coordinate system (not the lab coordinate system). If you want to run inverse dynamics, RRA, static optimization or CMC, you also need you ground forces in the model coordinate system as well. There are several ways to do this:
1) If you have your marker (trc file) and GRF (mot file) in your lab coordinates, you can use the opensim "Preview motion data" tool to convert your data to the correct coordinate system.
2) If you have the captured data in a c3d file (i.e. Vicon), you can download and use my C3D extraction toolbox for Matlab (https://simtk.org/home/c3dtoolbox) to produce all the necessary trc and mot files (in the correct model coordinate system) for importing your experimental data into OpenSim.
RE: scaling and IK
Thanks so much, You really help me a lot. now I can keep on my research!