Table 3.

Extracted statistical features from time domains for the feature matrix (x is the current signal).

Statistical Feature	Equation		Statistical Feature	Equation
Mean:	$\mu =\frac{1}{N}{\displaystyle \sum _{i-1}^N{x}_i}$	(7)	Skewness:	$x_{skewness}=\frac{1}{N}\frac{{\displaystyle \sum _{i=1}^N{(x_i-\mu )}^3}}{{\sigma }^3}$	(8)
Median:	$median={(\frac{(N+1)}{2})}^{th}value$	(9)	Kurtosis:	$x_{kurtosis}=\frac{1}{N}\frac{{\displaystyle \sum _{i=1}^N{(x_i-\mu )}^4}}{{\sigma }^4}$	(10)
Standard Deviation:	$\sigma =\sqrt{\frac{{\displaystyle \sum _{i=1}^N{(x_i-\mu )}^2}}{N-1}}$	(11)	Energy:	E = ${\displaystyle \sum _{i=1}^N{x}_i{}^2}$	(12)
Variance:	${\sigma }^2=\frac{{\displaystyle \sum _{i=1}^N{(x_i-\mu )}^2}}{N-1}$	(13)	RMS:	$X_{rms}=\frac{\sqrt{{\displaystyle \sum _{i=1}^N{x}_i{}^2}}}{N}$	(14)
Sum:	$\mathrm{Sum}={\displaystyle \sum _{i-1}^N{x}_i}$	(15)	Crest factor:	$C_f=\frac{X_{\max }}{X_{\min }}$	(16)