Page 1 of 1

Moments validation

Posted: Fri May 03, 2019 1:55 am
by saylee.p
Hi all,
I am doing analysis with methodology as Scale-IK-CMC. After analysis I validated the knee flexion angle output of opensim with vicon output using MATLAB and I am getting satisfactory results. After that I want to compare the moments output of opensim and vicon. For this I used analyze tool to find joint reaction load. But the output for X,y,z moment are very different than vicon.
I think this is happening because, to match the co-ordinate axes I used X and Y rotation in "c3dExport.m" while converting c3d to TRC and MOT. Will it affect the moment output?
If yes, then how can I compare the output for the same?
Also, is there any method to compare the muscle forces obtained from opensim with EMG output?

Re: Moments validation

Posted: Fri May 03, 2019 9:53 am
by tkuchida
is there any method to compare the muscle forces obtained from opensim with EMG output?
See, for example, the Case Study on page 17 of Hicks et al. (2015) and the papers referenced therein.
Hicks, J.L., Uchida, T.K., Seth, A., Rajagopal, A., Delp, S.L. Is my model good enough? Best practices for verification and validation of musculoskeletal models and simulations of movement. ASME Journal of Biomechanical Engineering 137(2):020905, 2015. https://nmbl.stanford.edu/publications/ ... ks2015.pdf

Re: Moments validation

Posted: Fri May 03, 2019 10:41 am
by saylee.p
Thank you for your input sir.
I will consider the same conditions of time delay and other parameters as explained in the paper for muscle force validation.
Also, I read the paper for other case studies also but couldn't find relevant answer for moment validation.
There is one case study for moment validation but it compares output of moment arm, passive moment generated by muscles, etc.(page 12) but they have compared same output with different opensim models.
So is there any method to compare the moment output with vicon data? Because I understand one thing that because of rotation in the data before analysis I cannot directly compare X moment of opensim with X moment of vicon, and so on.