About RRA

[Hang Xu]

when I read the handbook of Opensim, chapter 17 RRA,
I understood RRA contained RRA1 and RRA2, Does it mean when we do the RRA, we should do it twice? one for RRA1 and one for RRA2? If that is right, why the example 2354 and 2393 only have RRA files, not RRA1 and RRA2?
Thank you

[Ayman Habib]

Dear Hang,

I think you're looking at an older version of the User's Guide. RRA1 and RRA2 has been combined a while ago into one RRA step and the latest version of the User's Guide has been updated to reflect that.

Sorry for the confusion,
-Ayman

[Rebecca Routson]

About RRA...
I have nearly the example xml files... with changed COM for pelvis and 3 external forces... yet for some reason it won't run... error is as follows:

ArrayPtrs.get(aName): No object with name hip_flexion_r

Any thoughts as to why this is?

[Ayman Habib]

Rebecca,

Can you provide some context?

-Ayman

[Rebecca Routson]

This is for the stair climbing that you helped out with the ID for (Rob is my adviser). I took the RRA example xmls and changed the external forces and the COM of the pelvis (and of course my file names) only. When I press run it gives me that error. From what I can tell the simulation has just begun looking at the RRA_Actuators xml because in messages it says:

Adding force object set from C:\Applications\Becca_Clinical\Superstairs\Becca\Session 1\Becca_RRA_Actuators.xml

Do you want me to send you my files?
What other info can I give you?

Becca

[Yi Wang]

Hi Rebecca, the error "ArrayPtrs.get(aName): No object with name hip_flexion_r" which I usually encountered that when I run the ID or IK once. I just closed the OpenSim to reopen the .osim model to run the next step, which error in my opinion is kind of bug.

Hope to help.
Yi.
University of Utah

[Rebecca Routson]

Yi,

Genius! I restarted OpenSim and there was no more error message when I tried to run RRA.
Thanks!

Becca

[Rebecca Routson]

Okay now my problem with RRA is completely different. And I read previous posts of RRA trouble shooting which is why my COM was changed, but with every frame my model sinks lower and lower on the window.
Anyone have any thoughts as to why my simulation is doing that?
Thanks.
Becca

[Ayman Habib]

Rebecca,

Could be that GRFs are not being applied correctly, also make sure you "Replace" rather than "Append" actuators on the "Actuators and External Loads" tab of the CMC/RRA Tool. Check the gait2354 example folder to see how these should look like.

Good Luck,
-Ayman

[Rebecca Routson]

All that looks okay. i read in someone elses post to increase the excitations in the activations file, but I don't know which ones to increase and also how do I lock joints in my model?
B