Analysis of Thermal Flying-Height Control System About Humid Air Condition in Hard Disk Drive

This research investigates to analyze the effect of humid air on TFC system. Required parameters of humid air and flying attitude of slider are calculated. Condensation of air bearing at over the saturation vapor pressure is considered. Heat transfer coefficient for humid air condition is calculated. TFC simulation about humid air is conducted.

IDENTIFIKASI PARAMETER DAN PERANCANGAN SISTEM KENDALI PID UNTUK ANALISIS SIKAP TERBANG UAV [PARAMETER IDENTIFICATION AND DESIGN PID CONTROLLER FOR FLYING ATTITUDE ANALYSIS OF UAV]

Based on the state space yield first principle method knowed that characteristic of UAV is static stable. To get the near real condition doing verification of state space model by using the identification system toolbox of Matlab. The yield show that matrix element of state space is different both of them. Furher step is design the PID control system base on new state space, and for improve the performance system used Kalman filter. Key word: identification system, PID parameter, Kalman filter, Maximum overshoot

Surface Topology Optimization of Air Bearing Slider for Wear Durability in Magnetic Hard Disk Drives

In order to protect the slider and disk from excessive wear, a numerical scheme is proposed for transient dynamics at slider/disk interface with the emphasis on the slider wear mechanism and the surface topology optimization of sub-ambient pressure slider. For each transient flying height and slider attitude, the modified Reynolds lubrication equation is solved by the control volume method to obtain the simultaneous pressure distribution in the slider surface. Then the dynamic flying attitude of the slider subject to the calculated pressure distribution can be solved by the Quasi-Newton iteration method at each time step. On the basis of above work, the optimization of the slider surface topology is implemented, and it’s concluded that slider crown has the most significant impact on the dynamic flying attitude and stability. Finally, a sub-ambient pressure slider is designed, which can effectively avoid the slider wear and severe fault of hard disk drive.

A Performance Surface Method for Characterizing the Nonlinear Air Bearing Forces and Moments With Application to the Unloading Process

An efficient scheme was developed to analyze the dynamics of a magnetic head slider during the unloading process. The nonlinearity of the air bearing forces and moments was described by analytical expressions obtained from a surface fitting procedure. Combined with a dual-scale suspension model, the force and moment functions determined can be used to obtain the instantaneous flying attitude of the slider and the unloading time with a very short computation time, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.

Identification of the Multiple Flying Heights in a Loading Process

The slider of a Load/unload (LUL) drive can be loaded to a high flying stable state under certain conditions, which positions the read/write transducers much higher from the disk surface than the normal flying height (FH) and resulting in the issues in read or write. To avoid the issues caused by the high flying loading, it is necessary to find ways to recognize the existence of the high FH and eliminate it in the design stages. In this paper, we introduce a method that can identify the existences of the multiple FHs in loading process conveniently. The basic idea is to plot surfaces of air bearing forces in a domain of flying attitude, and then check if multiple FHs exist to generate the same air bearing forces that match the suspension forces. The analysis results indicate that the method is easy and efficient in identifying multiple FHs in loading process.

Simulating the Air Bearing Pressure and Flying Height in a Humid Environment

For a hard disk drive operating in a humid environment, the water vapor in the slider’s air bearing is typically compressed beyond its saturation vapor pressure, causing the vapor to condense. Consequently, the air bearing pressure decreases and the slider’s flying attitude adjusts to balance the forces from the suspension. A method for calculating this air bearing response to humid air is presented. Using two air bearing designs, several test cases are analyzed to illustrate the air bearing response for various temperatures and humidity levels. The calculated flying heights agree with those measured in commercial hard disk drives.

Performance of Sliders Flying Over Discrete-Track Media

A simulation method in which grooves are virtually distributed on the slider air bearing instead of on the grooved medium surface has been developed and used to investigate the performance of sliders flying over the surface of a discrete-track medium. The simulated flying height loss due to a discrete-track medium coincides well with the measured data, whereas the average-estimation method overestimates flying height loss. Among the characteristics of a slider flying over the surface of a discrete-track medium that were studied are the flying attitude, the effect of groove parameters on flying profile, and the flying height losses due to manufacturing variation and altitude. The results indicate that when a slider is flying over the surface of a discrete-track medium, it will have a higher 3σ of flying height, be more sensitive to altitude, and will have a greater flying height loss.