simtk.org

Hi, I'm new to OpenSim and muscloskeletal simulations. And I have a few questions about the dynamic analysis.
1. Can I extract both muscle activation and ground reaction forces from only kinematic data? like using OpenSimAD/Moco.
2. Can the results (like muscle forces) reproduce the original motion through physics simulation?
Especially, can the results (forces) of OpenSimAD/OpenSimMoco produce a motion through physics simulation or other ways?
3. I notice there are different type of actuators, ideal actuators and reverse actuators, what do they exactly do? Are they necessary in the analysis?

Thanks very much for your reply in advance!

Hi Inckie,

1. Yes you have run a dynamic simulation with OpenSimAD/Moco to extract muscle activations and ground reaction forces.
2. The tools we provide in the opencap-processing repo (like OpenSimAD) track the original motion, so it is not directly prescribing the motion. The motions should be close to the original motion, but it won't be exact. If you want to prescribe the exact motion, you would want to use MocoInverse. https://opensim-org.github.io/opensim-moco-site/docs/
3. Depends on your motion and if you need to add any other actuator other than muscles. For example, coordinate actuators can produce torques instantaneously, where activation actuators have some properties that mimic muscle activation.

Hope this helps,
Matt