“…After smoothing the original signal, the related feature quantity is extracted from the time and the frequency domains [25]. In order to make full use of the information in the original signal, 14 eigenvalues are extracted from 9 original signals, such as triaxial acceleration, triaxial angular velocity, and attitude angle of three axes, respectively, which are the mean value of acceleration, the mean value of synthetic acceleration, the variance of synthetic acceleration, the peak valley value of synthetic acceleration, the average synthetic angular velocity, the variance of synthetic angular velocity, the peak valley value of synthetic angular velocity, the covariance of synthetic acceleration and synthetic angular velocity, the change of attitude angle in X, Y, and Z directions in the time domain, and the energy value of acceleration signal in the frequency domain.…”