Initial Value Compensation Research Articles

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

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.

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

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.

Improvement of settling response of disk drive head positioning servo using mode switching control with initial value compensation

A Mode Switching Control (MSG) design method for disk drive head positioning servo is proposed. The MSC includes several controllers and switches from one to the other to achieve both precise positioning and short seek time requirements. The issue is settling, the transient state after switching. This paper proposes the initial value compensation (IVC) method to improve transient characteristics after switching. Under the IVC method, certain values are placed in the state variables of the controller or an additional input is added at switching. From experimental data, we have proved that IVC reduces overshoot and slow transient response after switching. Also this IVC method does not affect any closed loop characteristics such as stability.

Head positioning control for low sampling rate systems based on two degree-of-freedom control

To enhance formatting efficiency in high density hard disk drives, it is desirable to decrease the number of embedded servo signals. As a consequence, the sampling rate of servo systems has been becoming lower. In this situation, it is difficult to attain fast track seeking by using only a feedback controller. This paper presents a high-speed track seek technique, based on two degree-of-freedom control. A new reference model is developed by focusing on the attainment of fast track seeking through the effective use of a voice coil motor, which functions as a disk head actuator. The model generates reference trajectories, allowing high-speed movement. Also, in order to quickly settle the disk head to a target track under various disturbances, an initial value compensation (IVC) method to minimize a quadratic performance index is developed. Experimental results, using a 3-1/2 inch hard disk drive, confirm the validity of the proposed method.

Mode switching control design with initial value compensation and its application to head positioning control on magnetic disk drives

To meet an increasing demand for high performance and large-capacity in magnetic hard disk drives, both fast response and precise positioning are strongly required for the head positioning control. A mode switching control (MSC) system, which includes a track seeking controller, a track following controller, and a switching function, is widely used to meet this requirement. The issue for MSC is to confirm a design method of servo mode switching. This paper proposes the initial value compensation method (IVC). The IVC inputs certain initial values in the controller state variables at mode switching in order to improve the transient response after switching. There are two approaches to determine the values: (1) minimizing a linear-quadratic function of the plant state variables; and (2) cancelling the unfavorable poles of the transfer function between initial values and head position by relocating zeros. Some experimental results are shown to be effective.

モード切り換え型制御系における付加入力を用いた初期値補償設計と磁気ディスク装置への適用

モード切り換え型制御系における付加入力を用いた初期値補償設計と磁気ディスク装置への適用

モード切り換え型制御系の初期値補償設計と磁気ディスク装置ヘッド位置決めサーボ系への適用

モード切り換え型制御系の初期値補償設計と磁気ディスク装置ヘッド位置決めサーボ系への適用

磁気ディスク装置ヘッド位置決めサーボ系におけるサーボモード切り換え時の初期値補償問題の基礎検討

磁気ディスク装置ヘッド位置決めサーボ系におけるサーボモード切り換え時の初期値補償問題の基礎検討

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. >

最適ディジタルサーボ系の初期値補償とその応用

最適ディジタルサーボ系の初期値補償とその応用