Calculate per-segment centers of mass

Lower-level function that computes the center of mass for individual body segments from marker position data.

Usage

calculateSegmentCOM(pe, proximal_markers, distal_markers, com_fractions)

Arguments

pe

A PhysioExperiment object with position_x, position_y, and optionally position_z assays.

proximal_markers

Character vector of proximal marker names, one per segment.

distal_markers

Character vector of distal marker names, one per segment (same length as proximal_markers).

com_fractions

Numeric vector of COM proximal fractions (0-1), one per segment (same length as proximal_markers).

Value

A named list of matrices, one per segment. Each matrix has dimensions (n_frames x 2) for 2D data or (n_frames x 3) for 3D data, with columns named "x", "y", and (optionally) "z".

References

Winter DA (2009). "Biomechanics and Motor Control of Human Movement." 4th ed. John Wiley & Sons.

See also

calculateCOM() for whole-body center of mass, segmentParameters() for body segment inertial parameters.

Examples

if (FALSE) { # \dontrun{
pe <- readTRC("markers.trc")
seg_coms <- calculateSegmentCOM(
  pe,
  proximal_markers = c("RHip", "LHip"),
  distal_markers   = c("RKnee", "LKnee"),
  com_fractions    = c(0.4095, 0.4095)
)
} # }