Understanding the Some of the Column Heads in Ground Reaction Force Files provided with Gait2392_Simbody Folder

[Deepak Singh]

Hello Everyone,

I am trying to understand the meaning of some of the column heads/variables on the file namely, "subject01_ walk1_grf.mot" provided with the Gait2392_Simbody. I have understood some of the column heads/variables but I am not able to understand the meaning of the others as I haven't found their explanation in the documentation related to Inverse Dynamics.
The column heads/variables are presented in the attached picture and the not understood heads/variables are highlighted by yellow highlighter.
Alternatively, the not understood column heads are listed as follows:
1_ground_force_vx, 1_ground_force_vy,1_ground_force_vz,
1_ground_force_px, 1_ground_force_py, 1_ground_force_pz,
1_ground_torque_x, 1_ground_torque_y, 1_ground_torque_z.


I also looked at the associated .xml file titled "subject01_walk1_grf.xml" and in it, all these variables with "1_.." prefix are described as
"Identifier (string) to locate the point to be applied in the data
source."

I am not able to understand what these column head/ variables mean.
Please help as soon as possible.

Regards,
Deepak Singh

[Edward Syrett]

Hi,
These columns indicate the magnitude and position of the forces as seen by the force plate.

A column with the suffix, "_v_" indicates the vector (magnitude) of the force. So "_vx" would be the magnitude of the vector in the x direction (anterior/posterior), "_vy" would be the magnitude in the y direction (superior/inferior), and so on. A "_p_" column indicated the point of application on the force plate. "_px" would be the point of application in the x direction, and so on. Similarly, torques are expressed as magnitudes in the x,y,z planes as well, and are represented by ground_force_x (or y or z). The prefix "1" for all of these values indicates that these values are associated with force plate designated as "1".

Hope that helps.

[Deepak Singh]

Thanks for the clarification but I am still confused about the point that if the suffix "v" and others represent the values of force and related variables then why these variables are repeated with "1" suffix to designate for the recorded values at force plate "1"?
Does the earlier values in the column heads with suffixes and without "1" prefix represents the aggregate values of the force and torque variables?