Track Seeking Research Articles

映像機器のメカトロニクス 磁気ヘッドサーボ系における動作モードの切り替えを考慮したＨ２／Ｈ∞コントローラの設計

A control system design for head positioning in a rigid disk system has been studied in this paper. The use of multiple controllers is proposed to cope with variable operating modes. An H∞ controller with robust stability in the track following mode of a recording head and an H2 controller were designed by using a model-matching method for high-speed track seeking. The H2 controller is adapted each seek distance. Finally, a control system was constructed with both controllers. Closed-loop stability is maintained due to the structure of Yula parameterization8) even when the controllers are switched according to the operating mode.

Repetitive Track Seeking Algorithm for Optical Disk Drives

In order to achieve stable and rapid track seeking, a repetitive track seeking algorithm, which realizes highly accurate velocity control through velocity error integration, has been developed. Simulations and experiments show that the algorithm is effective in optical head velocity control. The algorithm reduces velocity error, compared with the conventional approach, so that the transient response at the seek end is greatly improved. The total seek time is reduced by adopting a reference velocity trajectory with larger deceleration rate, using this algorithm.

Time Optimal Seek Trajectories for a Dual Stage Optical Disk Drive Actuator

A closed-form solution for the time optimal control of a dual actuator disk drive system that takes into account the physical constraint limiting the relative motion of the fine and coarse actuator has been derived. The result is useful for determining track seeking strategies for high performance optical disks. The application of the necessary conditions to a simplified model of the compound actuator is presented and a solution derived.

A Numerical Simulation of the Head-Disk Assembly in Magnetic Hard Disk Files: Part I—Component Models

In previous papers the dynamics of air bearing sliders used to carry the read/write transducers in magnetic hard disk files has been studied. These studies are useful in evaluating the steady flying and stability of sliders subjected to various disturbances. They are particularly useful in finding the natural frequencies of the air bearings. However, in hard disk drives the sliders are attached to suspensions, which are highly specialized structures that connect the sliders to the positioning actuators. These suspensions have to be relatively stiff in lateral translation, but very flexible in pitch and roll. This latter feature is accomplished by the gimbal or flexure that connects the slider to the end of the suspension. The suspension-gimbal structure has its own natural frequencies, which can be excited by disturbances such as track seeking and impacting the actuator against the crash stop. In order to study the effect of these structures on the head-disk spacing it is necessary to include them in the numerical simulator. In this two part study such a simulator is developed. In Part I the component parts and their interfaces are modeled. In Part II the numerical simulation of the coupled system is accomplished and the numerical results of several sample simulations are presented and discussed.

Solid lubrication of gears and bearings in a space environment : P. H. Bowen, ASLE Trans., 7 (1964) 227; 10 figs., 4 tables, 6 refs.

The effect of air bearing design on the wear behavior of diamond-like carbon (DLC) coated sliders is investigated as a function of “interference height” and calculated contact force for sub-ambient pressure proximity recording sliders with contact stiffness of 1 and 0.25 mN/nm, respectively. The wear rate of DLC coated sliders was measured using Raman spectroscopy during track seeking of 1-h duration on a spin-stand and 1000-h duration in a 2.5-in. hard disk drive. In addition, the effect of air bearing design on flying height variations caused by a change in the static gimbal attitude and a change in altitude was estimated. The results show that wear of DLC coated sliders is proportional to the calculated contact force and that wear of the DLC overcoat levels off after 10km sliding distance regardless of slider design. Furthermore, we found that the amount of wear of the DLC overcoat for track seeking tests of 1-h duration is almost the same as that for a track seeking test of 1000-h duration.