Design of a high bandwidth moving-coil actuator with force couple actuation for HDDs]
TL;DR: In this paper, a novel high bandwidth moving-coil actuator is reported, where a special design in actuator construction leads to generation of pure torque in the actuator.
Abstract: This paper reports a novel high bandwidth moving-coil actuator. A special design in actuator construction leads to generation of pure torque in the actuator. With this special design the lateral quasi-rigid body vibration mode can be substantially suppressed. 2D FEA was carried out for the electromagnetic design to optimize the electromagnetic parameters and dimensions of the actuator. A 3D FEM solver was used to predict the characteristics of mechanical dynamics of the actuator. The electromagnetic characteristics, mechanical dynamics and performance of the actuator were measured. The results from simulation and experiment match quite well. The results show that the quasi-rigid body vibration mode is substantially suppressed and the primary resonance frequency is about 10 kHz in the novel actuator.
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TL;DR: In this article, the authors present the experimental modal testing and finite element modelling that are tailored to vibration testing in the head actuator assembly, based on voice coil motor without altering the modal property of the structure in actual operating condition.
19 citations
TL;DR: In this paper, a shearmode piezoelectric microactuator is integrated with a suspension for dual-stage actuation used in hard disk drives, and the results showed that 1.17-μm tip stroke could be obtained while the driving voltage was only 20 V.
Abstract: This paper presents a shear-mode piezoelectric microactuator that can be easily integrated with a suspension for dual stage actuation used in hard disk drives. The finite element method was employed to investigate the static and dynamic performance of the assembly using a simple cantilever suspension integrated with the microactuator. Experiments were also conducted to verify the numerical analysis results. A modern suspension integrated with the microactuator was then simulated based on the optimised structure of the actuator/suspension assembly, and the results showed that 1.17-μm tip stroke could be obtained while the driving voltage was only 20 V.
12 citations
06 Nov 2000
TL;DR: In this paper, a high bandwidth actuator assembly (HBX4) is developed for the applications of high TPI recording in hard disk drives, and a 3D finite element analysis (FEA) is conducted in the electromagnetic design to optimize some critical electromagnetic parameters and the main dimensions.
Abstract: A novel high bandwidth actuator assembly (HBX4) is developed for the applications of high TPI recording in hard disk drives. The novel design in voice coil motor (VCM) construction, with flat moving-coil, is as simple as a conventional one. The VCM generates orthogonal force or pure torque. A 3D finite element analysis (FEA) is conducted in the electromagnetic design to optimize some critical electromagnetic parameters and the main dimensions. A 3D FEA is also carried out to predict the dynamic performance. The study shows that the lateral quasirigid body vibration mode (QR mode), which limits the servo bandwidth in a conventional actuator, has been substantially suppressed. Measurement of the characteristics of a prototype is carried out and the result is discussed.
11 citations
01 Jan 2000
TL;DR: In this paper, an actuator assembly for the applications of high TPI recording in hard disk drives was developed for a novel high bandwidth actuator with flat moving-coil, which is as simple as a conventional one.
Abstract: A novel high bandwidth. actuator assembly is developed for the applications of high TPI recording in hard disk drives. The novel design in VCM construction, with flat moving- coil, is as simple as a conventional one. The VCM generates orthogonal force or pure torque. A 3D FEA is conducted in the electromagnetic design to optimize some critical electromagnetic parameters and the main dimensions. A 3D FEA is also carried out to predict the dynamic performance. The study shows that the quasi-rigid body vibration mode has been- substantially suppressed. Measurement of the characteristics of a prototype is carried out and the result is discussed.
10 citations
Cites background or methods from "Design of a high bandwidth moving-c..."
...Several efforts had been made to increase the servo bandwidth of the head positioning system [1]‐[ 3 ], [5]‐[15]....
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...Another way is to improve the mechanical dynamics of a conventional single stage VCM actuator [1]‐[ 3 ], [14], [15]....
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...Also the construction is different from the actuator developed in [ 3 ], in which the coil is perpendicalar to the seeking plane....
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...In the development of single actuator assemblies with substantially improved performance, especially in dynamic characteristics, in order to highly suppress the QR mode excited by the reaction force, several approaches, including moving-magnet actuators [2], [4] and dual and single moving-coil actuators [1], [ 3 ], have been investigated....
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...For a VCM-based actuator to produce orthogonal force or pure torque is an effective approach to increase the mechanical bandwidth [1]‐[ 3 ]....
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TL;DR: In this article, the authors investigated the influence of the driving force waveforms on residual vibrations and identified the characteristics of the waveform, which will lead to zero or very low residual vibrations.
Abstract: Track access time is an important parameter for high-performance hard disk drives (HDDs). Presently, the resonances of the head actuator caused by the pivot-bearing stiffness are an even more urgent problem, since these resonances have become the main design factor that limits further reduction of track access time and improvement of the servo control bandwidth in HDDs. Our objective in this paper is to investigate, from a mechanics and dynamics viewpoint, the influence of the driving force waveforms on residual vibrations and to identify the characteristics of the waveform, which will lead to zero or very low residual vibrations. Using a simplified model of a head actuator assembly and finite-element simulation, we show that the residual vibration of the head actuator assembly depends strongly on the waveform and the time duration of the driving impulse force. If suitable waveform and time duration of the seeking impulse force are appropriately chosen, very low track seeking residual vibrations and quick track access can be achieved.
8 citations
Cites background from "Design of a high bandwidth moving-c..."
...In order to suppress track seeking residual vibration and to increase the servo control bandwidth, Mah [ 2 ] reported a novel moving-coil head actuator....
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References
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TL;DR: In this article, a dual-stage actuator was developed using a piezoelectric device for a magnetic disk drive with a high track density over 15 kTPI, where the head position was detected by an optical method using a dot-pattern etched on a disk.
Abstract: A dual-stage actuator has been developed using a piezoelectric device for a magnetic disk drive with a high track density over 15 kTPI. This actuator uses a VCM (voice coil motor) rotary actuator as a coarse actuator and a piezoelectric actuator installed in a head-arm as a fine actuator. The stroke of the fine actuator is 4.6 mu m, which is sufficient for a track pitch of 1.5 mu m at 17 kTPI. The head position is detected by an optical method using a dot-pattern etched on a disk. The authors describe the design of the dual-stage actuator, including structural analysis, its static and dynamic characteristics, the dual-stage feedback control system. Experimental results of tracking with high accuracy on a 3.5-in disk-drive unit are presented. >
250 citations
TL;DR: In this paper, a milli-scale piggyback actuator for magnetic disk drives with a high track density was developed, which is comprised of a head suspension assembly supported by a 'flexural' cross-shaped spring, driven in the rotary direction by electromagnetic force.
Abstract: A new milli-scale piggyback actuator for magnetic disk drives with a high track density was developed. The movable part of this actuator is comprised of a head suspension assembly supported by a 'flexural' cross-shaped spring, driven in the rotary direction by electromagnetic force. The advantages are that the actuator moves over a long distance with small power and can be easily manufactured. Our dual-stage actuator system using the flexural milli-actuator can realize 25 kTPI.
85 citations
"Design of a high bandwidth moving-c..." refers methods in this paper
...One way is through the use of a a conventional actuator with a secondary-stage micro-actuator ([4]-[ 8 ])....
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01 May 1996
TL;DR: In this paper, a planar piezoelectric microactuator was developed for a hard disk drive and a two-stage servo controller was introduced to achieve high servo bandwidth over 1 kHz and enough tracking error reduction in the low-frequency region.
Abstract: The nonlinear response of a conventional actuator which depends on the ball-bearing friction is the main factor for determining the high track density of hard disk drives. We cannot get enough servo loop gain in the low-frequency region with a conventional single actuator because of its hysteresis characteristics. We have developed a new planar piezoelectric microactuator which is lightweight and applicable for a hard disk drive. Also we introduced a two-stage servo controller and realized a high servo bandwidth over 1 kHz and enough tracking-error reduction in the low-frequency region.
46 citations
TL;DR: In this paper, a bi-directional driving (BDD) electrostatic actuator with multiple parallel plate electrodes was proposed to realize high track density of hard disk drives (HDDs).
Abstract: We propose a new micro actuator to realize high track density of hard disk drives (HDDs). The proposed actuator is a bi-directional driving (BDD) electrostatic actuator with multiple parallel plate electrodes. The actuator generates a large force that is twice as much as the force of a conventional unidirectional driving (UDD) actuator, and it is fabricated by micro machining technologies. The driving theory is verified by experiments with a prototype. We demonstrate the capability of actuators which will achieve 40 k track per inch (TPI). The fabrication process of the actuators for 40 kTPI is under development.
31 citations
01 May 1996
TL;DR: In this article, a rotary actuator for HDDs is proposed to suppress the resonance gain in the quasi-rigid body mode caused by the stiffness of support bearings, which is called orthogonal driving.
Abstract: A new type of rotary actuator for HDDs is presented. To suppress the resonance gain in the quasi-rigid body mode caused by the stiffness of support bearings, we propose orthogonal driving. The designed actuator for a 3.5-inch drive shows a quasi-rigid body mode gain of less than 5 dB, and a fundamental resonance frequency of approximately 10 kHz. The results agree with those from finite element analysis.
27 citations