Multiple force plates

[Radhakrishnan Vignesh]

Hello,

I have generated the mot file for inverse dynamics from a .c3d file. The data contains forces measured from 5 force plates.
The generated mot file contains columns ground_force_1_vx, ground_force_1_vy, ground_force_1_vz...,ground_force_2_vx,ground_force_2_vy,ground_force_2_vz and so on.

The xml file, 'subject01_walk1_grf.xml' in example gait2354, does not allow me to add multple names in the force identifier section. It only allows me to add one of the above identifiers such as 'ground_force_1_v'.

Does this mean grf from only one plate is used? How do I get the tool to take in all the force plates for the calculation?

Thanks

[Ayman Habib]

Hello,

You can define multiple forces utilizing different columns from the same file. Assuming all these forces refer to the same location/orientation in ground or the respective bodies then applying multiple forces will have the effect of adding them up. If you have forces from one foot on multiple plates at the same time, however, you'll likely have to perform the combining of the forces externally before you get your data into OpenSim.

Hope this helps,
-Ayman

[Radhakrishnan Vignesh]

Hello Ayman,

Thanks for the reply . How do I specify multiple columns in the xml file ? Comma separating them or providing space between them similar to time range pops up errors.

And just to confirm , since there are six force plates , their location would be different but they all act on the same foot at different instances in time. So I would just provide the respective column names in the xml file

Thanks