Hand force measure

[Silvia Buscaglione]

Hi all,

I am relatively new to OpenSim and I would like to know if I can compute the force between the hand and externa object using Opensim.

Details of the study:
I am working with a dataset of two people interacting with a robotic system and I want to determine the force between the robotic interface and a person given the body's kinematics and force plate data.

So far, I have: (1) modeled the robotic handle in OpenSim as an external body in contact with the hand, (2) performed inverse kinematics, (3) performed the inverse dynamics, (4) ran the "Joint Reaction Analysis" to obtain the joint reaction forces between the hand and the handle.

HHowever, when comparing OpenSim's computed forces with the actual forces recorded from the robot in trials where only one person interacts with it, the results do not match. Right now, I am trying to determine whether this discrepancy is due to an issue in the OpenSim setup (e.g. how the external model of the handle is implemented) or if OpenSim simply cannot provide accurate force estimations in this scenario.

I hope my explanation is clear, and I would appreciate any insights or suggestions.

Thank you in advance,
Silvia