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All rows below this line contain the corresponding data in each column. Columns 2-4 (ground_force_vx, ground_force_vy, ground_force_vz) represent the x, y, and z components of the right foot's ground reaction force vector in a specific body coordinate system (ground for the model coordinate system). Columns 5-7 represent the x, y, and z components of the right foot's center of pressure (i.e., the point at which the ground reaction force is applied to the right foot). Similarly, columns 8-13 represent the ground reaction force vector and center of pressure for the left foot. Columns 14-16 represent the x, y, and z components of the right foot's ground reaction moment vector (typically in the model coordinate system). The last three columns represent the analogous quantities for the left foot.
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NaNs in your force file
NaNs are not compatible with any dynamics analysis and must be removed from mot files. Force data is splined during computation and occurrences of NaNs cause the entire force, moment, or COP column to become NaN. NaNs often occur when computing COP; more details can be found in the C3D files documentation.
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