Assistive forces as external forces

[Sivaprasad Kunnath]

Hi,

I am simulating an experiment with an assistive force as rehabilitative learning effort applied to a point on the wrist. This force produce the movement to the arm. I am curious on how to model the force. At present, I have the force to be a constant time series force. I want to know whether for the purpose of inverse dynamics and finding muscle activation using Moco, I can assume this assistive force to be the external force file.

I am confused at this point, as I have read that for the outcome of the experiment to be precise ( calculation of joint forces, torques and muscle activations and forces) an external force applied to the body grounded is essential to calculate the inverse dynamics using the closed chain newton-euler equations. However, I also saw some discussions in the forum, where it said it was okay to assume the perturbation forces as external forces. If that's the case, should I model this force to be applied on the wrist or provide an external force (like the grf data) on the grounded body and apply a point force on the wrist on it's frame. Thanks for the help.

Regards,
Siva