Wavelet construction based on lifting scheme and incipient fault feature extraction

To extract incipient fault feature of mechanical signal, a new method to construct wavelet according to the fault characteristics is presented. This method is based on lifting scheme, the initial set of finite biorthogonal filters is followed by lifting and dual lifting, and different lifting operators and dual lifting operators are obtained to construct new wavelet with particular properties. Modulus maxima of the detail signal after lifting in every operation cycle is extracted, and the position and time while weak signal singularity occurs are found. The engineering result confirms that the proposed method is better than the other wavelet methods for matching fault feature of mechanical signal, and the weak impact-rub fault caused by the axis misalignment and rotor imbalance of a key rotating machine in an oil refinery are desirably extracted.