HEAD-POSITIONING CONTROL IN TRIPLE-STAGE-ACTUATOR ENTERPRISE HARD DISK DRIVES USING MIXED H2/H∞ SYNTHESIS METHODOLOGIES

2021 ◽  
pp. 1-8
Author(s):  
Zhi Chen ◽  
Prateek Shah ◽  
Roberto Horowitz
Keyword(s):  
Hard Disk Drives ◽  
Voice Coil Motor ◽  
Hard Disk ◽  
Data Driven ◽  
Disk Drives ◽  
Positioning Accuracy ◽  
Positioning Control ◽  
Model Based ◽  
Head Positioning ◽  
Resonance Frequencies

Abstract The recent rapid growth in the cloud storage industry has strongly increased the demand for high-capacity hard disk drives (HDDs). Increasing the areal density brings new challenges to the high-accuracy head-positioning control in the next generation HDD development. Triple-stage-actuator (TSA) system is one of the emerging technologies that can achieve higher bandwidth than that of a dual-stage-actuator (DSA) system and improve the track-following performance. In this paper, we focus on the track-following controller design for TSA system with one voice coil motor (VCM) and two piezoelectric (PZT) actuators. Two types of mixed H2/Hinf synthesis methodologies based on model-based optimization and data-driven optimization are proposed to design the track-following controller for the TSA system. The TSA system can increase the bandwidth of the servo system and decrease the sensitivity to disturbances at the low-frequency range. While increasing the stroke limitation and the resonance frequency of the micro-actuator, the 3sigma the position error signals (PES) is reduced. The data-driven controller can achieve comparable head-positioning accuracy to the model-based controller when it converges to a local optimal solution. The simulation results show the feasibility and effectiveness of the TSA systems with a tertiary PZT actuator. We also analyze the effects of stroke limitations and resonance frequencies of the second/third-stage PZT actuators on the head-positioning accuracy. The results might provide a guideline for the TSA mechanical design.

High-bandwidth controller design for dual-stage actuator system in hard disk drives

2022 ◽  
pp. 107754632110623
Author(s):  
Shota Yabui ◽  
Takenori Atsumi
Keyword(s):  
Controller Design ◽  
Hard Disk Drives ◽  
Voice Coil Motor ◽  
Hard Disk ◽  
Disk Drives ◽  
Positioning Accuracy ◽  
Micro Actuator ◽  
Dual Stage ◽  
Actuator System ◽  
Dual Stage Actuator

Large-capacity hard disk drives are important for the development of an information society. The capacities of hard disk drives depend on the positioning accuracy of magnetic heads, which read and write digital data, in disk-positioning control systems. Therefore, it is necessary to improve positioning accuracy to develop hard disk drives with large capacities. Hard disk drives employ dual-stage actuator systems to accurately control the magnetic heads. A dual-stage actuator system consists of a voice coil motor and micro-actuator. In micro-actuators, there is a trade-off between head-positioning accuracy and stroke limitation. In particular, in a conventional controller design, the micro-actuator is required to actuate such that it compensates for low-frequency vibration. To overcome this trade-off, this study proposes a high-bandwidth controller design for the micro-actuator in a dual-stage actuator system. The proposed method can reduce the required stroke of the micro-actuator by increasing the gain of the feedback controller of the voice coil motor at low frequencies. Although the voice coil motor control loop becomes unstable, the micro-actuator stabilizes the entire feedback loop at high frequencies. As a result, the control system improves the positioning accuracy compared to that achieved by conventional control methods, and the required micro-actuator stroke is reduced.

Triple-Stage-Actuator System of Head-Positioning Control in Hard Disk Drives

2013 ◽  
Vol 49 (6) ◽  
pp. 2738-2743 ◽  
Author(s):  
Takenori Atsumi ◽  
Shigeo Nakamura ◽  
Masaru Furukawa ◽  
Irizo Naniwa ◽  
Junguo Xu
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Positioning Control ◽  
Head Positioning ◽  
Actuator System

Head-Positioning Control Using Resonant Modes in Hard Disk Drives

2005 ◽  
Vol 10 (4) ◽  
pp. 378-384 ◽  
Author(s):  
T. Atsumi ◽  
T. Arisaka ◽  
T. Shimizu ◽  
H. Masuda
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Positioning Control ◽  
Resonant Modes ◽  
Head Positioning

Head-Positioning Control of Hard Disk Drives Through the Integrated Design of Mechanical and Control Systems

2009 ◽  
Vol 3 (3) ◽  
pp. 277-285 ◽  
Author(s):  
Takenori Atsumi ◽  
Keyword(s):  
Control Systems ◽  
Hard Disk Drives ◽  
Integrated Design ◽  
Hard Disk ◽  
Disk Drive ◽  
Nanometer Scale ◽  
Disk Drives ◽  
Positioning Control ◽  
Head Positioning ◽  
And Control

A Hard Disk Drive (HDD) is an inexpensive mass-production product, but the head-positioning control systems of HDDs require nanometer-scale positioning performance. Therefore, we have studied head-positioning control systems of HDD using designs which integrate mechanical and control systems to improve their control performance while curbing cost increases. In this paper, we introduce “disturbance suppression in high-frequency ranges through phase stable design for high-order mechanical resonances” and “high servo-bandwidth design through mode shape design of mechanical resonance” as examples of techniques that have been developed and are easily applied to products.

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