Katsuhiro Tsuneta

A mode-switching controller with initial value compensation for hard disk drive servo control

Abstract In various kinds of servo positioning systems, both fast movement and precise positioning are required. To meet these demands, a mode-switching control (MSC) method, which has several controllers for each requirement and switches from one to the other, has been proposed. The issue raised by the use of this technique is the transient response after switching. This paper proposes the use of the initial value compensation (IVC) method to handle this problem. Under the IVC, initial values are placed in the controller state variables, or an additional input is added at switching. From experiments using hard disk drives, it is proved that the IVC improves transient responses after switching.

Improvement of servo robustness for digital sector servo system

In the smal I -sized magnetic hard disk drives the sector servo system is commmonly used for positioning control. The sector servo is a sampling servo and often its sampling period has to be longer than desired because of the data format structure. This long sampling period somet imes causes undesi red transient responses at seeking. In t his study the initial value compen- sation theory is applied to the sector servo. This compensation method is to input initial values, calculated by minimizing a performance index, into sett I ing servo compensators when the servo mode is switched from seeking to settling. Several experimental results show this method improves the servo performance.

Improvement of servo robustness for digital sector servo system (hard disk drives)

In order to improve the servo performance of the digital sector servo, the authors developed initial value compensation for the digital variable structure control system and applied it to a 3.5-in disk drive. This compensation method involves inputting initial values, calculated by minimizing a performance index, into settling servo compensators when the servo mode is switched from seeking to settling. Implementation is quite easy for digital systems. Experimental results show good robust performances for large velocity fluctuations at switching. >

Design of Mode Switching Controller with Initial Value Compensation and Its Application to Disk Drive Servo Control

Abstract In various kinds of servo positioning systems, both fast movement and precise positioning are required. To meet these demands, a Mode Switching Control (MSC) method., which has several controllers for each requirement and switches from one to the other, has been proposed. The issue is a transient response after switching. This paper proposes the initial value compensation (IVC) method. Under the IVC, initial values are placed in the controller state variables or an additional input is added at switching. From experiment using hard disk drives, it is proved that the IVC improves transient responses after switching.