Flying Height Control for a 2-DOF Tripad Slider in Hard Disk Drives With Switched Regulator

2005 ◽  
Author(s):  
Zhizheng Wu ◽  
Foued Ben Amara
Keyword(s):  
Control Method ◽  
Hard Disk Drives ◽  
Surface Profile ◽  
Hard Disk ◽  
Disk Surface ◽  
Switched System ◽  
Flying Height ◽  
Disk Drives ◽  
The Stability ◽  
Adaptive Regulator

Maintaining a constant small flying height of the read/write head is an important target in the design of the ultra high storage density hard disk drives. One effective way to achieve this goal is to use a feedback regulator to suppress the flying height variations. For low flying heights, the read/write head enters into intermittent contact with the disk surface, which results in a switched system regulation problem. In this paper a new control method is proposed to maintain the flying height at its desired value based on the switched system models, despite the unknown microwaviness in the disk surface profile and the unpredictability in the switching times. First, a switched system model is constructed. Then, a Q parameterized set of switched regulators is constructed and the stability of the resulting switched closed loop system is analyzed. Online adaptive regulator tuning is then performed by adjusting the Q parameter in the controller to achieve regulation. Simulation results are presented to illustrate the effectiveness of the proposed method.

Contact and temperature rise of thermal flying height control sliders in hard disk drives

2012 ◽  
Vol 18 (9-10) ◽  
pp. 1693-1701 ◽  
Author(s):  
Liane Matthes ◽  
Uwe Boettcher ◽  
Bernhard Knigge ◽  
Raymond de Callafon ◽  
Frank E. Talke
Keyword(s):  
Temperature Rise ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Flying Height ◽  
Disk Drives ◽  
Height Control ◽  
Thermal Flying Height Control

Design and Dynamics of Flying Height Control Slider With Piezoelectric Nanoactuator in Hard Disk Drives

2006 ◽  
Vol 129 (1) ◽  
pp. 161-170 ◽  
Author(s):  
Jia-Yang Juang ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Numerical Study ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Areal Density ◽  
Flying Height ◽  
Air Bearing ◽  
Disk Drives ◽  
Adhesion Forces ◽  
Surface Design ◽  
Ultrahigh Density

To achieve the areal density goal in hard disk drives of 1Tbit∕in.2 the minimum physical spacing or flying height (FH) between the read/write element and disk must be reduced to ∼2nm. A brief review of several FH adjustment schemes is first presented and discussed. Previous research showed that the actuation efficiency (defined as the ratio of the FH reduction to the stroke) was low due to the significant air bearing coupling. In this paper, an air bearing surface design, Slider B, for a FH control slider with a piezoelectric nanoactuator is proposed to achieve virtually 100% efficiency and to increase dynamics stability by minimizing the nanoscale adhesion forces. A numerical study was conducted to investigate both the static and dynamic performances of the Slider B, such as uniformity of gap FH with near-zero roll over the entire disk, ultrahigh roll stiffness and damping, low nanoscale adhesion forces, uniform FH track-seeking motion, dynamic load/unload, and FH modulation. Slider B was found to exhibit an overall enhancement in performance, stability, and reliability in ultrahigh density magnetic recording.

scholarly journals Servo signal processing for flying height control in hard disk drives

2011 ◽  
Vol 17 (5-7) ◽  
pp. 937-944 ◽  
Author(s):  
Uwe Boettcher ◽  
Christopher A. Lacey ◽  
Hui Li ◽  
Kensuke Amemiya ◽  
Raymond A. de Callafon ◽  
...  
Keyword(s):  
Signal Processing ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Flying Height ◽  
Disk Drives ◽  
Height Control ◽  
Servo Signal

Local Adaptive Multi-Grid Control Volume Method for the Air Bearing Problem in Hard Disk Drives

2012 ◽  
Author(s):  
Liping Li ◽  
David B. Bogy
Keyword(s):  
Control Volume ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Adaptive Grid ◽  
Air Bearing ◽  
Disk Drives ◽  
Control Volume Method ◽  
Generating Method ◽  
The Stability ◽  
Volume Method

A new local adaptive grid-generating algorithm is developed and integrated with the multi-grid control volume method to simulate the steady state flying condition of air bearing sliders in HDDs (Hard Disk Drives) accurately and efficiently. Two sliders are used to demonstrate the applicability of this method. The results show that this new local adaptive grid-generating method improves substantially the stability and efficiency of the simulation scheme.

Flying height measurement while seeking in hard disk drives

1998 ◽  
Vol 34 (4) ◽  
pp. 1765-1767 ◽  
Author(s):  
B.C. Schardt ◽  
E. Schreck ◽  
R. Sonnenfeld ◽  
Q. Haddock ◽  
J.R. Haggis
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Flying Height ◽  
Disk Drives ◽  
Height Measurement

An Efficient FE Analysis for Complex Low Flying Air-Bearing Slider Designs in Hard Disk Drives—Part I: Static Solution

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Puneet Bhargava ◽  
David B. Bogy
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Static Solution ◽  
Flying Height ◽  
Air Bearing ◽  
Pressure Gradients ◽  
Disk Drives ◽  
Bearing Stiffness ◽  
Novel Method ◽  
Mesh Refinements

Prediction of the steady state flying height and attitude of air-bearing sliders in hard disk drives via simulations is the basis of their design process. Over the past few years air-bearing surfaces have become increasingly complex incorporating deep etches and steep wall profiles. In this paper we present a novel method of solving the inverse problem for air-bearing sliders in hard disk drives that works well for such new designs. We also present a new method for calculating the static air-bearing stiffness by solving three linear systems of equations. The formulation is implemented, and convergence studies are carried out for the method. Mesh refinements based on flux jumps and pressure gradients are found to work better than those based on other criteria.

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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