Vector coding (coupling angle) between two joints

Vector coding quantifies coordination from the angle-angle diagram: the coupling angle is the orientation of the vector between successive points, and each frame is classified into in-phase (both joints rotating together), anti-phase (opposite), proximal-phase (angle1 dominant) or distal-phase (angle2 dominant) coordination (Chang et al. 2008; Needham et al. 2014).

Usage

vectorCoding(angle1, angle2)

Arguments

angle1, angle2

Numeric joint-angle series of equal length; angle1 is the proximal joint (horizontal axis of the angle-angle plot).

Value

a vector_coding list: coupling_angle (degrees, 0-360, length n-1), pattern (a factor per frame) and proportions (time fraction per pattern).

References

Chang R, et al. (2008) J Biomech 41:3101-3105; Needham RA, et al. (2014) J Biomech 47:1235-1241.

See also

continuousRelativePhase(), coordinationVariability()

Examples

t <- seq(0, 2 * pi, length.out = 101)
vectorCoding(sin(t), sin(t))$proportions            # all in-phase
#> pattern
#>   in_phase anti_phase   proximal     distal 
#>          1          0          0          0