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How does openSim reads angle data
Posted: Tue Apr 24, 2018 12:16 pm
by vgallego
Right now I am loading a motion file to the gait2392_simbody model and the model seems to be moving in a similar way that it should but not exactly the same. So i went to the coordinates window and looked at the angles in there and the don't match the ones in the .mot file.
Does anybody knows why this happens? and how can I fix it?
I am doing a Squat an the model has the feet weld to the ground. Thanks!!
Re: How does openSim reads angle data
Posted: Tue Apr 24, 2018 4:00 pm
by tkuchida
The .mot file may specify poses that cannot be achieved by the model without violating its kinematic constraints. If so, you may need to modify the model such that it can reach the desired poses. The appropriate modifications---and model in general---may depend on your research question.
Re: How does openSim reads angle data
Posted: Wed Apr 25, 2018 7:13 am
by vgallego
how do I know o where can I look what are the kinematics constrains of the model. And an extra question, do yo know where I can find motion data of a squat?
Re: How does openSim reads angle data
Posted: Thu Apr 26, 2018 12:15 am
by tkuchida
how do I know o where can I look what are the kinematics constrains of the model.
You mentioned in your first post that you have welded the feet to the ground. How to improve the model depends on which coordinates are not being tracked, what level of precision is expected given your data, what your research question is, etc. It may also be necessary to improve how the model was scaled.
Also note that gait2392 model may not be appropriate for simulating a squat. As stated on the "Musculoskeletal Models" page in the Confluence documentation: "Results may be inaccurate during motions with high degrees of knee flexion." (
https://simtk-confluence.stanford.edu/d ... tal+Models).
Re: How does openSim reads angle data
Posted: Fri Apr 27, 2018 11:40 am
by vgallego
Do you know any model that is good to model a squat? based on the high degrees of knee flexion
Re: How does openSim reads angle data
Posted: Fri Apr 27, 2018 12:27 pm
by tkuchida
Do you know any model that is good to model a squat? based on the high degrees of knee flexion
Adrian Lai published a modified version of the Rajagopal model that is "capable of simulating movements that involve substantial hip and knee flexion". Here's the simtk project page: "A musculoskeletal model for simulations that involve high hip and knee flexion",
https://simtk.org/projects/model-high-flex.