Nonlinear Filtering Method for Corrosion Detection on Pole Tips

This chapter presents two corrosion detection methods based on the contour information of the pole tip. The first estimates contour length of the pole tip in order to analyze the occurrence of corrosion. The second implements nonlinear analysis to detect pitting corrosion. The nonlinear filter shows higher accuracy for detecting minute corrosion and is more favorable than the previous studies. The chapter covers the automatic detection of corrosion on pole tip based on longitudinal recording technology. Both methods can be applied to the contour of pole tips. The chapter covers the recent developments in perpendicular magnetic recording (PMR) and its challenges with corrosion. In a filtering process, the goal is to identify the signal samples that are corrupted by noise and restore them to the original signal values. The chapter adopts median e-filter for detection of corrosion on the contour of pole tips.