Multi-resolution HDD contact detection technique for low SNR applications

• Published in: Microsystem technologies Vol. 20; no. 8-9; pp. 1597 - 1603
• Main Authors: Daugela, Antanas, Trantham, Jon D., Ryun, Scott E., Tadepalli, Srinivas
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2014; Springer
• Subjects: Applied sciences; Electronics; Electronics and Microelectronics; Engineering; Exact sciences and technology; Instrumentation; Magnetic and optical mass memories; Mechanical Engineering; Nanotechnology; Storage and reproduction of information; Technical Paper; Contact Detection; Acoustic Emission; Voice Coil Motor; Hard Disk Drive; Discrete Wavelet Transform; Head disk interface; Positioning; Driving device; Methodology; Wavelet transformation; Modulation; Thermal pulse; Hard disk; Multiresolution analysis; Implementation
• ISSN: 0946-7076; 1432-1858
• DOI: 10.1007/s00542-014-2180-1

The accurate calibration of active flying height in a hard disk drive (HDD) is an essential metrology for proper drive operation. Detecting head-disk contact of a head-disk-interface (HDI) is a critical step in calibrating the active fly height. Proposed is a head-disc contact detection technique that is an improved adaptive discrete wavelet transform (ADWT) methodology that can be integrated into an advanced HDD. The method is designed to process low SNR head/disc proximity probe data during a thermal protrusion pulse and extract HDI head modulation signatures correlating them with the contact event. The significance of the proposed ADWT implementation is in fact that thousands of DWT coefficients can be represented by a simple statistically derived data set of four parameters that can be tracked to declare the contact. This compact approach enables a practical, cost-effective ADWT implementation into the HDD hardware architecture using existing micro-processors and on-board memory.