[Moco] feature request: a normalize state tracking error function similiar to setNormalizeTrackingError for contact errors

[nik-steventon]

Hi,

I was wondering if it would be possible to create a function that would normalize the state values to their peak value in a coordinate.sto file? This would be similar to the setNormalizeTrackingError for a ContactTrackingGoal, which normalizes tracking errors to the peak contact force values. I think this would make it easier to set relative weights as muscle activations, grfs, and states errors would all be bound between 0-1. If my understanding is correct, this would avoid the optimizer preferencing tracking joint ranges of motion which have high values and hopefully negate the need to set other tracking values significantly higher to account for this.

Thanks in advance.

Regards,
Nik

[nickbianco]

Hi @nik-steventon. Good idea! We will keep this in mind for future development plans.

[nik-steventon]

Thanks for the reply @nickbianco, that would be great! In the meantime, is there anyway to access the source code for the setNormalizeTrackingError() function? No worries if not, but I wouldn't mind having a go at pulling together some code to replicate this function for state errors and would be happy to share it here and on the Moco forum if I can get it to work.

[nickbianco]

You can find the source code for the GRF normalization here:

opensim-core/OpenSim/Moco/MocoGoal/MocoContactTrackingGoal.cpp

Line 200 in a5bb517

// Compute normalization factors.

If you're able to replicate this behavior for MocoStateTrackingGoal and want to create a PR, let me know!