Help to start using opensim

[fady alnajjar]

Hi to all,

I hope that I will be welcomed between you, since I am just a beginner. Indeed, I have just started using OPENSIM from the last week. I believe that I will need it very much to support my project.
I have installed and performed the whole attached tutorials. I have also seen some of the online workshop videos and the presentations. But I still have problems to start practically using it. I have some questions that I hope it will make things clear to me. I am sorry for this long introduction and the long following questions:

I have a model in mind to build that actually represents around 10 muscles, and 4 degree of freedom. As I understand from reading some parts in the forums here; it seems that the easiest way is to download a ready model and try to modify from it. Is that true? I have downloaded the model (gait2392_simbody_v18.osim) and tried to modify on it. For example:
 Deleted all muscles that I am not interested in by editing manually the (gait2392_simbody_v18.osim) file, this step worked OK. I also think I can add other muscles to the model from other model. Is this can work also fine?
 I also tried to do the same as above to remove some slides from the coordinate’s window, however, it gives me error messages when I save the file and try to load it again. Is there any simple way to remove unwanted coordinates?
 I have modified the gait2392_simbody_v18.osim file and added into it some markersets that I need (virtual markers). This appears correctly in the model. Now I have (.trc) file for a walking body that I want to scale it into my model to move it. How I can do that? Any simple steps to do so?

Thank you very much for your cooperation.

[fady alnajjar]

I have tried to look at the example came with sim, and I think I figured out some steps regarding to scaling.

Regarding to the coordinates, I will try to modify the *.osim manually again, till somebody advice more easy way.

thanks

[Ayman Habib]

Hi Fady,

The coordinates are part of the joint definition, joint types dictate how many coordinates to use (for example a pin joint has exactly 1 coordinate and we can't make it any other number). If there's a coordinate that you want to fix then the easiest way would be to lock it (using the coordinate sliders/buttons in the GUI or using the locked tag in the osim file under the <Coordinate> tag.

Hope this helps, and please let me know if you have any questions.

Good luck,
-Ayman

[fady alnajjar]

Thank you very much Dr. Ayman, This will help.