Discrete-time LQG/LTR dual-stage controller design in magnetic disk drives

2001 ◽  
Vol 37 (4) ◽  
pp. 1891-1895 ◽  
Author(s):  
Sang-Min Suh ◽  
Chung Choo Chung ◽  
Seung-Hi Lee
Keyword(s):  
Discrete Time ◽  
Controller Design ◽  
Disk Drives ◽  
Magnetic Disk ◽  
Dual Stage

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.

Optimal Sliding Mode Dual-Stage Actuator Control in Computer Disk Drives

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Seung-Hi Lee
Keyword(s):  
Discrete Time ◽  
Sliding Mode ◽  
Voice Coil Motor ◽  
Disk Drives ◽  
Flexible Mode ◽  
Control Scheme ◽  
Dual Stage ◽  
Actuator Control ◽  
Dual Stage Actuator ◽  
Computer Disk

This paper presents a discrete-time design of a dual-stage actuator control system with sliding mode for computer disk drives. A state estimator based discrete-time boundary layer sliding mode control scheme is developed for a dual-stage actuator, which consists of a voice coil motor and a microactuator. Considering dominant microactuator flexible mode dynamics and the interaction between the two actuators, an optimal sliding hyperplane is designed to maximize their cooperation so as to attain desired responses. An application example demonstrates the utility of the proposed sliding mode dual-stage actuator control scheme for track-seek in the microactuator range, settle, and track-follow.

Sequential vs. Parallel Synthesis for Dual-Stage Hard Disk Drives

2012 ◽  
Author(s):  
Craig E. Stensland ◽  
Mark Bedillion
Keyword(s):  
Controller Design ◽  
Hard Disk Drives ◽  
Voice Coil Motor ◽  
Hard Disk ◽  
Parallel Synthesis ◽  
Disk Drives ◽  
Parallel Design ◽  
High Bandwidth ◽  
Dual Stage ◽  
Single Input

Modern hard disk drives (HDDs) use single-input, dual-output (SIDO) controllers to control a dual-stage plant consisting of a large-stroke voice coil motor (VCM) and a short-stroke, high-bandwidth piezoelectric microactuator (PZT). Various methods have been proposed to perform the SIDO controller design; among the most commonly used approaches is μ-synthesis. While μ-synthesis generates stable controllers for the overall system, it does not guarantee stability of the VCM-only loop in the presence of microactuator saturation or failure. One approach to the DISO design that maintains VCM-only stability is the sequential design of VCM and PZT controllers. This paper presents a systematic study of sequential vs. parallel design. Designs are evaluated by comparing values of μ obtained for equivalent designs between the sequential and parallel approaches. The circle criterion is used to test stability of the system under saturation. Performance of sequential and parallel designs in shock events are tested in simulation.

Effect of dual-stage actuator on positioning accuracy in 10 k rpm magnetic disk drives

2001 ◽  
Vol 37 (2) ◽  
pp. 955-958 ◽  
Author(s):  
S. Koganezawa ◽  
T. Hara ◽  
Y. Uematsu ◽  
T. Yamada
Keyword(s):  
Disk Drives ◽  
Positioning Accuracy ◽  
Magnetic Disk ◽  
Dual Stage ◽  
Dual Stage Actuator
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