Design and Analysis of a Disk Drive Actuator for Commutational Ramp Loading

2006 ◽  
Vol 129 (3) ◽  
pp. 346-360
Author(s):  
Ryan T. Ratliff ◽  
Prabhakar R. Pagilla
Keyword(s):  
Design Procedure ◽  
Voice Coil Motor ◽  
Nonlinear Effects ◽  
Disk Drive ◽  
Friction Torque ◽  
Disk Drives ◽  
Performance Requirements ◽  
Actuator System ◽  
Shock Protection ◽  
Ramp Load

A voice-coil motor actuator system is designed to perform a unique disk drive ramp load/unload operation. The design eliminates the necessity of increased material requirements common in ramp load disk drives. Therefore, disk drives with lower cost, higher performance actuators can realize the linear shock protection benefits of ramp loading. This study offers a complete, systematic design procedure together with required analysis for manufacture of a commutational ramp load/unload drive. The actuator is designed and optimized to meet specific move-time performance requirements. When used for ramp load/unload, however, there exists a location where input current has no influence on actuator motion. An input polarity reversal is required within the uncontrollable region to sustain the direction of actuator motion. A magnetic, restorative bias is designed that prevents the actuator from resting in the uncontrollable region while providing resistance to rotational shock effects. A state trajectory is designed that, when tracked, moves the actuator through the uncontrollable set for a successful load onto the disk at the desired load velocity. A ramp load controller is designed to track the trajectory and handle the nonlinear effects from bias and friction torque. The unique disk drive is manufactured and experiments are performed to demonstrate effectiveness of the complete design strategy.

Commutational Output Feedback Control for Disk Drive Ramp Loading

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Ryan T. Ratliff ◽  
Prabhakar R. Pagilla
Keyword(s):  
Output Feedback ◽  
Output Feedback Control ◽  
Nonlinear Effects ◽  
Disk Drive ◽  
Friction Torque ◽  
Disk Drives ◽  
Actuator Dynamics ◽  
Velocity Information ◽  
Shock Protection ◽  
Ramp Load

The feasibility of a ramp load controller using a conventional disk drive actuator is investigated. The controller eliminates the necessity of increased material requirements common in ramp load disk drives. Therefore, disk drives with lower cost, higher performance actuators can realize the linear shock protection benefits of ramp loading. A disk drive designed with a conventional actuator is outfitted with a ramp and optimized for ramp load operation. While on the ramp, there exists a set in the state space where the actuator dynamics are uncontrollable. An input commutation is required within the uncontrollable region to sustain the direction of actuator motion. Additionally, the motor torque factor, magnetic restoration bias, and friction torque are nonlinear and can be represented by functions that are Lipschitz within the actuator ramp angle. A state trajectory is generated that, when tracked, moves the actuator through the uncontrollable set for a successful load onto the disk at the desired load velocity. Because position and velocity information are not available during a load maneuver, an output feedback controller is necessary. A stable, output feedback tracking controller is designed to track the trajectory and handle the nonlinear effects. A unique disk drive is manufactured and experiments are performed to verify the complete ramp loading design strategy.

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.

Passive Vibration Control of the Head Actuator Assembly in Hard Disk Drive

2001 ◽  
Author(s):  
LiMei Xu ◽  
Sheng Zeng ◽  
NingQun Guo ◽  
Rongming Lin
Keyword(s):  
Rigid Body ◽  
Performance Improvement ◽  
Hard Disk Drives ◽  
Voice Coil Motor ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Drives ◽  
Head Positioning ◽  
Hollow Space ◽  
The Voice

Abstract It is known that a quasi-rigid body mode exists in hard disk drives in the frequency range from 3 to 6 kHz and it is caused by the flexibility of the pivot, the mass and structure of the head actuator assembly. The mode hinders performance improvement of servo system in bandwidth. In this paper, a tuned damping device is proposed to suppress this mode. The damping device is to be installed on the arm and hollow space within the voice coil motor on the HDDs. The dynamic characteristics of the head actuator assembly with the tuned damping device are measured in both frequency domain and time domain. It is shown that the tuned damping device can work effectively to suppress the quasi-rigid body vibration of the head actuator assembly and minimize the residual vibration in head positioning.

Effects of Temperature on Particle Trajectory Inside the Helium-Filled Hard Disk Drive

2016 ◽  
Author(s):  
Yuwen Zhu ◽  
Guoqing Zhang ◽  
Shengnan Shen ◽  
Hui Li ◽  
Yun Yang ◽  
...  
Keyword(s):  
Particle Trajectory ◽  
Hard Disk Drives ◽  
Voice Coil Motor ◽  
Hard Disk ◽  
Disk Drive ◽  
Spindle Motor ◽  
Disk Drives ◽  
Submicron Particle ◽  
Effects Of Temperature ◽  
Al2o3 Particles

The presence of particles, which can intrude into the air bearing, is one of the most common factors in the failure of hard disk drives (HDDs). Previous works investigated the particle trajectory inside air-filled drives without considering the temperature effects on the distribution of particles. Actually, for the submicron particle, particle trajectory and trapping status are affected by the temperature gradient since the thermophoretic force cannot be ignored. In this paper, considering the major heat generation components such as spindle motor and voice coil motor (VCM), the trajectories and trapping status for Al2O3 particles with diameter of 0.3 μm inside a 2.5 inch helium-filled drive are simulated by the commercial computational fluid dynamics solver FLUENT with user-defined functions (UDFs). The trapping criterion for Al2O3 particles are used as the boundary conditions for the different colliding surfaces.

Dynamic characteristics of a voice coil motor for a high performance disk drive

1989 ◽  
Vol 25 (4) ◽  
pp. 3073-3075 ◽  
Author(s):  
Y. Hirano ◽  
J. Naruse ◽  
R. Tsuchiyama
Keyword(s):  
Dynamic Characteristics ◽  
High Performance ◽  
Voice Coil Motor ◽  
Disk Drive

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.

System Dynamics and Disk Drive Head Position Error Prediction in a Data Storage Box

2014 ◽  
Author(s):  
Lidu Huang ◽  
Chiao-ping Roger Ku ◽  
Jean O’Young ◽  
Toshiki Hirano
Keyword(s):  
Data Storage ◽  
Storage System ◽  
Disk Drive ◽  
Head Position ◽  
Position Error ◽  
System Level ◽  
Disk Drives ◽  
Data Storage System ◽  
Mechanical Disturbances ◽  
System Transfer Function

Disk drives are packed at ever dense arrangement in a modern data storage system, internal and external mechanical disturbances can have a great effect to disk drive’s read and write performances. The VCM torque generated during seeking affects its own as well as neighboring drives head position. In this study, we modeled a storage box with multiple HDDs installed to obtain mechanical system transfer function. The mechanical excitation is characterized by VCM torque, and HDD operational vibration behaviors on linear and rotational shakers are measured. A system level hybrid method predicting HDD head position error in a data storage box is described, and both analytical and measured results will be presented.

Flying Clearance Distribution With Thermo-Mechanical Actuation of Hard Disk Drive

2008 ◽  
Author(s):  
Sung-Chang Lee ◽  
George W. Tyndall ◽  
Mike Suk
Keyword(s):  
Environmental Change ◽  
Temperature Change ◽  
Temperature Sensitivity ◽  
Temperature Compensation ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Drives ◽  
Compensation Scheme ◽  
Mechanical Actuation

Flying clearance distribution with thermo-mechanical actuation is characterized. Especially, what factors contributing to variation of flying clearance are identified based on thermo-mechanical actuation profiles taken from burn-in process of hard disk drives and Gage R&R test of touch down repeatability. In addition, the effect of static temperature compensation scheme on flying clearance distribution is investigated and disadvantages of static adaptation to temperature change are identified. In order to avoid catastrophic early HDI failures due to poor static temperature compensation, we need to dynamically adjust flying clearance whenever environmental change is detected. Otherwise we need to utilize individual temperature sensitivity values of each flying head to adjust thermo-mechanical actuation amount accordingly with temperature change.

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