Update MocoTrajectory::generateSpeedsFromValues() to not override auxiliary states

[nickbianco]

Fixes issue #3477

Brief summary of changes

This PR updates the logic in MocoTrajectory::generateSpeedsFromValues() so that any auxiliary (e.g., muscle-related) states do not get overridden. I've added some accessors to MocoTrajectory to make this fix more convenient, but these are nice additions beyond this fix.

Testing I've completed

• Added test to testMocoInterface.cpp

Looking for feedback on...

CHANGELOG.md (choose one)

• updated.

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This change is 

[aymanhab]

LGTM, other than naming conventions that I was a little unclear on, if used widely elsewhere then you can ignore

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @nickbianco)

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OpenSim/Moco/MocoTrajectory.h line 476 at r1 (raw file):

    int getNumSpeeds() const {
        ensureUnsealed();
        return (int)getSpeedIndices().size();

Not sure about the ensureUnsealed call having any side-effects, but if not then ignore

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OpenSim/Moco/MocoTrajectory.h line 485 at r1 (raw file):

    int getNumAuxiliaryStates() const {
        ensureUnsealed();

Naming: in the past auxiliary states were used to imply muscle states and that was confusing, if this is used to mean something else across the board in Moco world then ignore

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OpenSim/Moco/MocoTrajectory.h line 551 at r1 (raw file):

                multibodyStateNames.push_back(name);
            }
        }

Is the implication that /value, /speed are used exclusively for multibody states?

[nickbianco]

Thanks @aymanhab! Let me know if my responses are sufficient, or if you'd like any changes.

Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @aymanhab)

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OpenSim/Moco/MocoTrajectory.h line 476 at r1 (raw file):

Previously, aymanhab (Ayman Habib) wrote…

Not sure about the ensureUnsealed call having any side-effects, but if not then ignore

If the trajectory is sealed, you shouldn't be able to access anything. This call was missing from this method.

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OpenSim/Moco/MocoTrajectory.h line 485 at r1 (raw file):

Previously, aymanhab (Ayman Habib) wrote…

Naming: in the past auxiliary states were used to imply muscle states and that was confusing, if this is used to mean something else across the board in Moco world then ignore

Here, auxiliary states is referring to any state that is not a multibody state, including the muscle states but not limited to them. I believe "auxiliary" is the term Simbody uses for the non-multibody states.

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OpenSim/Moco/MocoTrajectory.h line 551 at r1 (raw file):

Previously, aymanhab (Ayman Habib) wrote…

Is the implication that /value, /speed are used exclusively for multibody states?

Yes, but I'm not sure if that's explicitly enforced anywhere. /value and /speed are baked in the code in many other places, so this assumption is mostly safe for now. If we wanted to allow non-multibody state names ending in '/value' or '/speed' we would need more comprehensive changes.

[aymanhab]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @nickbianco)