Unable to optimize the Gait_2392_simbody model muscle via python tool

[KehanZOU]

Hi there,
I tried to use the tool to optimize the parameter of a model scaled from standard gait_2392_simbody model, but the software failed at getting model definations, where the error message says 'NoneType' object has no attribute 'text' when locating the parent frame of the muscle. I googled this problem and it says it is likely that the software failed to locate the called attribute of parent frame. I compared the example Arnold reference model and gait_2392, yet I found no significant difference in these two files which may lead to this problem. If anyone can kindly give me a clue I would be more than grateful.
FYI, the gait_2392_simbody model I used is taken from OpenSim 4.3 folder, but OpenSim 3.3 was installed and set to path. I'm not sure if this problem can be caused by this variation.
Best regards,
Kehan ZOU

[modenaxe]

Hello, this is an interesting problem... @eravera can probably help you more than me with the Python code.
If you want to try the MATLAB version, on the other hand, I would suggest to use the code from this branch: https://github.com/modenaxe/MuscleParamOptimizer/tree/updOS4 and OpenSim 4 and then let me know if that worked?

[KehanZOU]

Hi Modenese, thank u for your kind reply. I tried the MATLAB version in the branch u sent me, and it turn out that it works fine on standard Gait_2392 models and many other models that I have scaled from 2392, except for the one I used before. I guess there's some unknown error wrong with the Osim model I used for testing, and guess I'll try to re-scale a model and try again.

[eravera]

Hi @KehanZOU and @modenaxe

This issue could be due to some differences in the .xml organization in the gait2392 model. Some definitions has changed between OpenSim versions and this could be a problem for the algorithm.
You can trying converting the model in the new version with the OpenSim GUI. Or you can shared the model that you are using with me and I can try to reproduce the error.

[KehanZOU]

Hi eravera, thank u for your kind reply. I guess u r right on the xml organization explaination. Previously I used the MuscleParamOptimizer released for OpenSim 3, but My models are from OpenSim 4, and this could be the reason. It turn out that the model I used previously has some unknown problems and couldn't work well with the MuscleParamOptimizer. I changed another osim model and it seems like the MATLAB version for OpenSim 4 works out fine. I also tried to optimize the renewed model with the branch for OpenSim 3 , but it has the same issue, so I agree that the xml organization between the two versions can be a reason. @modenaxe is very kind and sent me the branch for OpenSim 4 and I guess I'll try to carry out the same procedure using the python code in the branch for OpenSim 4 and I'll let u know if the problem has been solved.