Accurate detection of light contact of thermal fly-height control sliders using advanced singular value decomposition

The dynamic contact and nonlinear dynamics of TFC slider has been widely characterized by harmonics in FFT of vibrational signal. The accurate determination of the harmonics have been challenging as the small peaks of the harmonics in FFT are frequently hidden by varied deterministic vibrations and noise. In this paper, advanced singular value decomposition method is employed to enhance the accuracy of the detection of the multi-harmonics. The track matrix of attractor of TFC slider vibration time series in light contact with disk is reconstructed in phase space. By using singular value decomposition theory, the singular spectrum from reconstructed attractor track matrix is estimated in order to increase the signal-to-noise ratio of the LDV response signal, which is further used for the accurate detection of uncertain, abrupt information and for early slider-disk light contact detection. This approach enables signal noise attenuation, which is critical to the accurate detection of weak harmonics, and enables the accurate extraction of light contact information, particularly for the transient abrupt cases, as well as improves the accuracy of harmonics-based system identification.