Induced Acceleration Analysis - error sources

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Rodrigo Mateus
Posts: 60
Joined: Thu Feb 22, 2018 3:07 am

Induced Acceleration Analysis - error sources

Post by Rodrigo Mateus » Mon Jan 28, 2019 6:58 am

Hi there,

I am having some difficulties in finding the sources of error in an induced accelerations analysis. For example, the plot for the centre of mass acceleration along the fore/aft and vertical directions show rapid variations along the task which does not seem consistent with what is expected.
ia.png
ia.png (148.68 KiB) Viewed 471 times
Does anyone have a suggestion for assessing where the error may come from?

Thank you in advance.

Rodrigo Mateus
Tags:
OpenSim 3.3 and Earlier
GUI
IAA
Windows
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Ayman Habib
Posts: 2255
Joined: Fri Apr 01, 2005 12:24 pm

Re: Induced Acceleration Analysis - error sources

Post by Ayman Habib » Mon Jan 28, 2019 12:10 pm

Hello,

Are you running the analysis on states files (e.g. resulting from a forward simulation, or CMC?) You may find this page helpful in describing the inputs to IAA.
https://simtk-confluence.stanford.edu/d ... ts+for+IAA

Best regards,
-Ayman
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Rodrigo Mateus
Posts: 60
Joined: Thu Feb 22, 2018 3:07 am

Re: Induced Acceleration Analysis - error sources

Post by Rodrigo Mateus » Tue Jan 29, 2019 7:54 am

Hello,

Yes I am using the states and controls from CMC. To give another situation, I concluded that the greatest contributor to the acceleration of the centre of mass along the fore-aft direction are the quadriceps, as you can see from the figure below. However the unexpected spikes keep appearing.
ia3.png
ia3.png (160.9 KiB) Viewed 435 times
I am also applying a RollingOnSurface constraint with a force threshold of 6 N.

Best regards,

Rodrigo Mateus
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