Centre of pressure definition

[Marta Meneses]

Hi everyone!

I'm having some trouble defining the centre of pressure of the gound reaction forces. Are the coordinates local (foot reference) or global?

Thanks,

Marta

[Rudolf Klemetti]

GLOBAL!!!

[Marta Meneses]

Thanks!I'm doing it rigth then!The error must be on the calculation...

[Ayman Habib]

Hi Marta,

The files passed in to the tools are usually the output from motion capture systems so they are global (wrt ground frame). When applying these forces and torques however, we transform these forces to the frame of the body to which the forces are applied (based on provided external_loads_kinematics_file). We're changing the XML tags to make this more clear in the next version of OpenSim.

Hope this helps,
-Ayman

[Marta Meneses]

Thanks Ayman!

I would like to ask you another question:

I've added some markers to a mode yesterday. When I try now to open the model in OpenSim GUI, it keeps giving this error:

"Coordinate Coupler: unknown independent coordinate shoulder_elv"

However, this coordinates IS defined in the .osim file!

Any idea?

[Ayman Habib]

Hi Marta,

Are you sure the name is shoulder_elv and not shoulder_elev ? If so, and you're sure the coordinates in question exist, plese file a bug report and attach the model (and any other relevant files) and I'll check it out.

Best,
-Ayman