envelope: RMS or MA Envelope of an EMG

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

View source: R/envelope.R

Description

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

Usage

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

Arguments

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.

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.

Value

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

Author(s)

J.A. Guerrero [email protected]mx

References

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

See Also

emg, movingaverage

Examples

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# 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")

biosignalEMG documentation built on Feb. 18, 2018, 9:02 a.m.