MocoTrack dynamic consistency

[Mohammadreza Rezaie]

Hi, I have a few questions about MocoTrack and how to achieve dynamic consistency. By studying the example file (exampleMocoTrack.py), I see that the model has strong residual actuators (CoordinateActuators with high optimal force for the ground-pelvis coordinates), and the weight of their controls was increased by 10 times. So the optimizer minimizes those controls further, and hence, residual forces/moments would be reduced.

1) Can I use weak residual actuators instead of increasing the weight of the residual controls in MocoControlGoal?

2) I'm trying to track the markers and GRF, simultaneously, in the same model with strong residual actuators. If I ignore increasing the weight of the residual controls (or disable the MocoControlGoal in general), is this simulation still dynamically consistent? I think the answer is yes since the error of contact tracking is minimized, which could mean that the kinematics and kinetics are consistent. My initial simplified test ended up with an absolute max value of 0.6 for residual actuators which was 400 in inverse dynamics.

3) Also, in a simulation which tracks markers and GRF, and minimizes joint contact force, do I still need to append GRF to the model through ModOpAddExternalLoads? Perhaps the answer is no, because of the contact tracking goal.

I was wondering if you could help me with these stupid questions, and thank you in advance.