Compute joint power from moment and angular velocity

Joint power is the product of the net joint moment and the joint angular velocity. Positive power (generation) reflects concentric muscle action doing work on the segment; negative power (absorption) reflects eccentric action absorbing energy. Set split = TRUE to return the generation and absorption components alongside the total.

Usage

computeJointPower(moment, angular_velocity, split = FALSE)

Arguments

moment

Numeric vector of joint moment values.

angular_velocity

Numeric vector of joint angular velocity in rad/s.

split

Logical; if TRUE, return a data frame with the total power split into non-negative generation (P > 0) and non-positive absorption (P < 0) components. Default FALSE returns the total power vector (backward compatible).

Value

If split = FALSE, a numeric vector of joint power (W). If split = TRUE, a data frame with columns power, generation, and absorption (each in W); generation + absorption == power elementwise.

References

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

See also

inverseDynamics2D() for computing joint moments in 2D, inverseDynamics3D() for computing joint moments in 3D, jointWork() for integrating power into concentric/eccentric work, labelPowerBursts() for Winter power-burst nomenclature.

Examples

computeJointPower(c(10, 12, 8), c(2, 1.5, 1))
#> [1] 20 18  8
computeJointPower(c(10, -12, 8), c(2, 1.5, -1), split = TRUE)
#>   power generation absorption
#> 1    20         20          0
#> 2   -18          0        -18
#> 3    -8          0         -8