Estimation of EMG Variables during Voluntary Isometric Contractions - Essay Example

“The generalization together with the autoregressive model opens new possibilities for studying models of variable expected returns, which might be the key to the understanding of many phenomena” (Jianping Mei,1994, P. 4).1.2.4 Autoregressive moving average model (ARMA):ARMA is the generalized model of an autoregressive model; it provides high resolution than the AR model. It consists of two parts AR part and the MA part. Autoregressive-moving-average (ARMA) models are the mathematical models of the persistence or autocorrelation, in a time series.

ARMA modeling can contribute to considering the physical system by revealing something about the physical process that builds persistence into the series. ARMA models can also be used to predict the performance of a time series from past values alone. Such a prediction can be used as a baseline to analyze the possible importance of other variables to the system. Another newly developed method is Ph.D. which produces the ultimate spectral resolution and yields the most accurate estimate of the spectrum.

Another important factor to be considered while using these methods is signal to noise ratio (SNR). The SNR should be low enough to use both AR and ARMA methods. For all other cases, FFT is still employed for analysis. “One of the important shortcomings of ARMA-type model is the assumption of constant variance” (Knight & Satchell, 2007, P. 2).1.3. EMG:Electromyography or EMG is the process used to test the activity of muscle fibers. Her main concentration is made on the lower back muscles and their fatigue.

“EMG involves testing the electrical activity of muscles. Often, EMG testing is performed with another test that measures the conducting function of nerves”. This signal recorded on the electromyograph is the input to the PSD function. (Huff, et al, 2011).1.4. Application of PSD in EMG:The briefly discussed methods can be used for spectral analysis in different application areas, namely assessment of muscle fatigue using electromyography (EMG) signals. Surface EMG can be used to analyze muscle activity from a global perspective.