Residuals Reduction Algorithm (RRA)

Jens van der Wees · Post by **Jens van der Wees** » Fri May 03, 2024 4:59 am

I am performing RRA on some experimental data of people with CP. They performed slow and fast walking trials, each consisting of 5 trials (so 10 in total). Do I have to perform RRA on each and every trial? or just twice (slow and fast walking)?

Carmichael Ong · Post by **Carmichael Ong** » Mon May 06, 2024 5:34 pm

I've seen this done both ways. An RRA on each trial would say that it could be more dynamically consistent to adjust mass and inertia of bodies for each trial. This might make sense, for instance, when a whole torso is lumped into one body and there is no single mass/inertia that describes the system correctly.

However, this ignores the assumption that we would expect an individual to not be changing too much between trials. Because of this, some people will run a single RRA and use the same model for all trials.

Overall, though, it may be worth trying both and seeing how different your results are. Perhaps it may not differ for your specific task, but might in another person's task.

One other tool you could check out is https://addbiomechanics.org/. This helps process multiple trials of IK and ID all at the same time (and can be a replacement for RRA).

Jens van der Wees · Post by **Jens van der Wees** » Wed May 08, 2024 5:38 am

Thanks a lot. I'll have a look at it!

Jens van der Wees · Post by **Jens van der Wees** » Thu Jun 06, 2024 12:59 am

Hi! there i am again, with another question on RRA and it's corresponding actuators file. I have a very small question, so i hope it is simple for you to answer as well. Does it matter if the optimal forces in the actuators file are high, in order to perform RRA with it?

Kind regards,
Jens van der Wees

Residuals Reduction Algorithm (RRA)

Residuals Reduction Algorithm (RRA)

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Re: Residuals Reduction Algorithm (RRA)