Track-following controller design of MEMS based dual-stage servos in magnetic hard disk drives

2002 ◽  
Author(s):  
Y. Li ◽  
R. Horowitz
Keyword(s):  
Controller Design ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Dual Stage ◽  
Magnetic Hard Disk

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.

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.

Application of Mixed H2/H∞ Data Driven Control Design to Dual Stage Hard Disk Drives

2018 ◽  
Author(s):  
Omid Bagherieh ◽  
Prateek Shah ◽  
Roberto Horowitz
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Control Design ◽  
Hard Disk ◽  
Data Driven ◽  
Disk Drives ◽  
Design Strategies ◽  
Data Driven Approach ◽  
Dual Stage

A data driven control design approach in the frequency domain is used to design track following feedback controllers for dual-stage hard disk drives using multiple data measurements. The advantage of the data driven approach over model based approach is that, in the former approach the controllers are directly designed from frequency responses of the plant, hence avoiding any model mismatch. The feedback controller is considered to have a Sensitivity Decoupling Structure. The data driven approach utilizes H∞ and H2 norms as the control objectives. The H∞ norm is used to shape the closed loop transfer functions and ensure closed loop stability. The H2 norm is used to constrain and/or minimize the variance of the relevant signals in time domain. The control objectives are posed as a locally convex optimization problem. Two design strategies for the dual-stage hard disk drive are presented.

scholarly journals Design and Implementation of Dual-Stage Track-Following Control for Hard Disk Drives

2009 ◽  
Author(s):  
Jianbin Nie ◽  
Roberto Horowitz
Keyword(s):  
Hard Disk Drives ◽  
Servo System ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Drives ◽  
Outer Loop ◽  
Servo Systems ◽  
Design And Implementation ◽  
Integral Action ◽  
Dual Stage

This paper discusses the design and implementation of two track-following controllers for dual-stage hard disk drive servo systems. The first controller is designed by combining an outer loop sensitivity-decoupling (SD) controller with an inner loop disturbance observer (DOB). The second is designed by combining mixed H2/H∞ synthesis techniques with an add-on integral action. The designed controllers were implemented and evaluated on a disk drive with a PZT-actuated suspension-based dual-stage servo system. Position error signal (PES) for the servo system was obtained by measuring the slider displacement with an LDV and injecting a simulated track runout.

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