Calibrate an EMG-driven model to measured joint moments

CEINMS-style calibration: adjusts a small set of parameters (force scale, activation time constant, EMG non-linearity) to minimise the RMS error between the model's predicted joint moment and a measured reference moment (e.g. from inverse dynamics).

Usage

calibrateEMGDrivenModel(
  emg,
  norm_len,
  norm_vel,
  moment_arm,
  reference_moment,
  sr,
  params = emgDrivenParams()
)

Arguments

emg

EMG envelope.

norm_len, norm_vel

Normalised fiber kinematics.

moment_arm

Moment arm (m).

reference_moment

Measured joint moment to match (N.m).

sr

Sampling rate (Hz).

params

Starting parameters from emgDrivenParams().

Value

A list with calibrated params, rmse, r (correlation of predicted vs reference moment), par (optimised values), and convergence.

Examples

sr <- 200; t <- seq(0, 0.5, by = 1 / sr)
emg <- pmax(sin(2 * pi * 2 * t), 0)
truth <- emgDrivenJointMoment(
  emgDrivenForce(emg, norm_len = 1, norm_vel = 0, sr = sr,
                 params = emgDrivenParams(max_isometric_force = 900)),
  moment_arm = 0.03)
fit <- calibrateEMGDrivenModel(emg, norm_len = 1, norm_vel = 0,
                               moment_arm = 0.03, reference_moment = truth,
                               sr = sr)
fit$rmse
#> [1] 0.02653788