envelope: RMS or MA Envelope of an EMG
In biosignalEMG: Tools for Electromyogram Signals (EMG) Analysis

Description Usage Arguments Details Value Author(s) References See Also Examples

Computes the RMS-envelope, the MA-envelope ot the LE-envelope of an EMG signal.

1	envelope(data, channel, method = c("MA","RMS","LE"), wsize, cutoff, n = 2, data.name, ...)

`data`	an ‘emg’ object.
`channel`	in case of multi-channel data, `channel` is the specific channel to be considered by the procedure. Possible values: a character vector specifying the name of the channel to be considered (case sensitive) or a numeric value specifying the channel to be considered (number of column in `data`).
`method`	a string, "MA" (default) for MA-envelope, "RMS" for the RMS-envelope and "LE" for the LE-envelope.
`wsize`	determines the length of the moving window that is used to calculate the local averages of the data in RMS and MA envelopes.
`cutoff`	cutoff frequency in Hertz for the lowpass filter used in LE-envelope.
`n`	filter order for the lowpass filter used in LE-envelope.
`data.name`	a string specifying the name of the variable which will appears on the plots. If empty or not provided is taken from the object given as `data`.
`...`	Optional parameters for a MA-envelope: `rtype` for a rectification. See `rectification` for details.

The MA-envelope corresponds to the moving average of the rectified EMG.

The RMS-envelope corresponds to the moving average of

y_i=(x_i-mu)^2

where x_i is each value of the EMG signal and mu is the overall mean of the EMG signal.

LE-envelope or linear envelope is lowpass filtered rectified signal.

An ‘emg’ object containing the envelope of the EMG.

J.A. Guerrero jaguerrero@correo.uaa.mx

Konrad P. (2005) The ABC of EMG: A Practical Introduction to Kinesiological Electromyography. Version 1.0, Noraxon INC. USA.

emg, movingaverage

# Simulate 5 seconds of an EMG
emgx <- syntheticemg(n.length.out = 5000, on.sd = 1, on.duration.mean = 350, 
    on.duration.sd = 10, off.sd = 0.05, off.duration.mean = 300, off.duration.sd = 20, 
    on.mode.pos = 0.75, shape.factor = 0.5, samplingrate = 1000, units = "mV", 
    data.name = "Synthetic EMG")

# MA-envelope
emgma <- envelope(emgx, method = "MA", wsize = 60)
# Superimpose the envelope on the EMG
plot(emgx, main = "MA-envelope")
plot(emgma, add = TRUE, lwd = 4, col = "red")

# RMS-envelope
emgrms <- envelope(emgx, method = "RMS", wsize = 60)
# Superimpose the envelope on the EMG
plot(emgx, main = "RMS-envelope")
plot(emgrms, add = TRUE, lwd = 4, col = "red")

# RMS-envelope
emgle <- envelope(emgx, method = "LE", cutoff = 10) #10Hz
# Superimpose the envelope on the EMG
plot(emgx, main = "LE-envelope")
plot(emgle, add = TRUE, lwd = 4, col = "red")