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The model disappeared during RRA
Posted: Mon Dec 07, 2020 6:30 pm
by dongdongwang527
Hello, dear opensim users.The data I collected can be scaled and IK can be performed smoothly, but during the completion of the RRA process, the model suddenly disappeared, and the information bar prompts that the quality of each segment is nan. Do you have this situation, or do you know how to deal with this situation?
It really made me confused,looking foward for yours reply!Thanks!
Re: The model disappeared during RRA
Posted: Wed Dec 09, 2020 5:33 am
by mitkof6
Hi,
This can happen if ground reaction forces are not applied correctly or if the tracking tasks' gains are small.
In the first case, please make sure that for the time interval of the RRA analysis you always apply ground reaction forces. If they are not applied, the model falls and is not dynamically consistent. To do the RRA properly, I always perform inverse dynamics and check the residual forces at the pelvis to make sure that ground reaction forces are properly applied.
Regarding the second point, if ID has low residuals at the pelvis, then RRA may fail to track the movement only if the tracking gains are low.
Re: The model disappeared during RRA
Posted: Fri Jun 11, 2021 12:05 pm
by qhumphrey
mitkof6 wrote: ↑Wed Dec 09, 2020 5:33 am
Hi,
This can happen if ground reaction forces are not applied correctly or if the tracking tasks' gains are small.
In the first case, please make sure that for the time interval of the RRA analysis you always apply ground reaction forces. If they are not applied, the model falls and is not dynamically consistent. To do the RRA properly, I always perform inverse dynamics and check the residual forces at the pelvis to make sure that ground reaction forces are properly applied.
Regarding the second point, if ID has low residuals at the pelvis, then RRA may fail to track the movement only if the tracking gains are low.
I am having the same issue and I'm not sure I understand what you mean. Does the interval come from the ID or from another file?