RRA Fy is too high

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Bruce de Jongh
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Joined: Wed Feb 05, 2014 3:14 am

RRA Fy is too high

Post by Bruce de Jongh » Tue May 26, 2015 7:59 am

Hi All

I am currently using the RRA and CMC tool for my own data with the gait2393 model supplied by Opensim. I am analysing data for one step on a force plate. I only run the analysis for the duration of the stance phase on the force plate.

I have scaled my model, performed an IK and an ID and am now attempting to run the RRA while keeping the residuals in the range specified by opensim. I have the correct pelvis COM in my xmls and have applied the weight changes to the body segments. This has decreased my avg residual forces to within the specified range, but the rms and max residual forces are still too high for Fy and nothing else. There is also a bit of pelvis drift.

My maximum Fy is roughly 50 N.

Can anyone please give me advice on how to reduce the residual force while stopping the pelvis from drifting. I have tried increasing the weighting of pelvis tx, ty and tz but that increases the residual forces.

Thank you in advance for your help.

Kind regards,

Bruce de Jongh
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jimmy d
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Joined: Thu Oct 04, 2007 11:51 pm

Re: RRA Fy is too high

Post by jimmy d » Wed May 27, 2015 12:11 pm

Still sounds like your masses are off. Have iterated on increasing your masses to compensate?
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Bruce de Jongh
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Joined: Wed Feb 05, 2014 3:14 am

Re: RRA Fy is too high

Post by Bruce de Jongh » Thu May 28, 2015 4:02 am

Hi James

Thank you for the reply. Yes I have a few times, but am still unable to get the residual force within the required range. The moment is OK. I am using the tracking task weightings used for the gait2392 model.

Regards,
Bruce
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