A three-dimensional model for lubricant depletion under sliding condition on bit patterned media of hard disk drives

2018 ◽  
Vol 123 (18) ◽  
pp. 184502
Author(s):  
Lin Wu
Keyword(s):  
Hard Disk Drives ◽  
Three Dimensional ◽  
Hard Disk ◽  
Disk Drives ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Lubricant Depletion

Depletion of Moleculary Thin Lubricant Under Flying Head in Hard Disk Drives

2007 ◽  
Author(s):  
Kenji Yanagisawa ◽  
Youichi Kawakubo ◽  
Masato Yoshino
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Lubricant Film ◽  
Simulation Program ◽  
Disk Drives ◽  
Lubricant Thickness ◽  
Magnetic Disk ◽  
Lubricant Depletion ◽  
Lubricant Films

In Hard Disk Drives, lubricants are very important materials to reduce head and disk wear. Therefore, it is necessary to know the lubricant depletion under flying heads. Lubricant depletion due to flying heads has been studied experimentally. We developed simulation program to calculate numerically the change in lubricant thickness under a flying head on a thin-film magnetic disk from 10nm thick lubricant film. In recent HDDs, the lubricants thickness has become molecularly thin and polar lubricants have been used. In this paper, we took account of thickness-dependent lubricants diffusion and viscosity in our simulations to calculate a 1.2 nm thick polar lubricant film used in recent HDDs. The simulated results considering the thickness-dependent diffusion and viscosity showed that depletion was small in molecularly thin lubricant films. We considered it necessary to include thickness-dependent diffusion and viscosity in lubricant depletion simulation.

DSP Implementation of a Direct Adaptive Feedforward Control Algorithm for Rejecting Repeatable Runout in Hard Disk Drives

2016 ◽  
Author(s):  
Jinwen Pan ◽  
Prateek Shah ◽  
Roberto Horowitz
Keyword(s):  
Digital Signal Processor ◽  
Control Method ◽  
Feedforward Control ◽  
Hard Disk Drives ◽  
Digital Signal ◽  
Hard Disk ◽  
Disk Drives ◽  
Bit Patterned Media ◽  
Dsp Implementation ◽  
Adaptive Feedforward

A direct adaptive feedforward control method for tracking repeatable runout (RRO) in bit patterned media recording (BPMR) hard disk drives (HDD) is proposed. The technique estimates the system parameters and the residual RRO simultaneously and constructs a feedforward signal based on a known regressor. An improved version of the proposed algorithm to avoid matrix inversion and reduce computation complexity is given. Results for both MATLAB simulation and digital signal processor (DSP) implementation are provided to verify the effectiveness of the proposed algorithm.

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