RRA tool

[Ursula Trinler]

Thank you a lot Ayman this was indeed helpful!

I will have a closer look on my GRF and the scaling of the model now to figure out if the problem of sinking into the ground relates to these factors.

Ursula

[abeer mohamed]

Hello

I found a this under RRA troubleshooting


"'''If RRA is failing, try increasing the maximum excitation for residuals by orders of magnitude until the simulation runs, then try working your way back down while also "relaxing" tracking weights on coordinates.""""

however my question is in which OpenSim file can I adjust the maximum excitation for residual.
thanks
abeer

[Ursula Trinler]

My model is still not walking properly, it still sinks when using RRA. what I've done so far is:

- Adjust the CoM of the pelvis
- Adjusted tibia and femur from "MANUAL SCALING" to "MEASUREMENT BASED SCALING" using the scaling tool
- Smoothed the GRF with a 25Hz low-pass filter

Does someone has any other suggestion what I could do?

Thank you!

[abeer mohamed]

Hi
my model stop sinking after I add CMC_actuator to RRA_actuatort in "the addational force set file" window. however my average residule after adjusting torso are all small values except FY which is 984.99. I do not know if applying both actuator files is right or wrong, but the model walks fine.
thanks
abeer
thanks

[Ursula Trinler]

Thank you Abeer for this suggestion, unfortunately it does not work with my data.

I will have a closer look on my experimental data again. Some test data I captured last year are working totally fine, we made some changes to the force plates since then and my new data from two subjects have the sinking phenomena now. I suspect that it perhaps has something to do with the CoP and the force not matching together.

I will use the Caltester to ensure the force plates are working properly and will do then a new test measurement. Will report my results then.

Best,
Ursula

[abeer mohamed]

Hi Ursula
I can send you sample of my gait data to try it, if you are not very sure about yours. let me know if this can help.
thanks
abeer

[jimmy d]

Ursula,
Has the height of the forceplate (h) been taken into account with exporting the forceplate data?
The offset of the forceplate height needs to be used so that the COP is registered at the point of contact, not at the level of the forceplate.

let us know,
-james

[Ursula Trinler]

Hi James,

Thanks a lot for this suggestion! I had something similar in mind. I will have a look if the offset is taken into account and latest on Monday, after my meeting with my supervisors, I will come back to you!

Thank you for the help!
Ursula

[Ursula Trinler]

Hi James,

I feel a bit embarrassed, I found the solution and it is, of course, quite obvious. Because the trailing leg of the first step has no GRF, the model sinks because some force is missing for the whole system. When I start the calculations after toe off of the trailing leg, the model is not sinking anymore! Does that make sense?

I will run RRA for some more trials and if I experience, however, still some problems I will write in this tread again.

Thanks a lot for you support!!!
Best wishes from the UK
Ursula

[Ursula Trinler]

One question I would still have, is it possible to calculate the missing force for the trailing leg for the first step of the leading leg on the first force plate force plate through OpenSim? Or do I need experimental data and have to use one force plate more to get appropriate data?

Cheers,
Ursula