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Neural Networks Input Techniques to Maintain a Small Skew Angle in Bit-Patterned Magnetic Recording with a V-Shaped Read-Head Array
(2023-01-01)
Fatika, Kirana Alif
;
Koonkarnkhai, Santi
;
Kovintavewat, Piya
;
Warisarn, Chanon
The demand for enormous storage devices has kept increasing, leading to the development of various advanced technologies with a vast storage capacity. Extensive numbers of related research studies have been aiming at optimizing code design and algorithms analytically; however, enacting them on practical devices has been scarce. Achieving this demand might bring some obstacles called two-dimensional interference and skew angle (SA). To meet the challenge of the obstacle, we propose a SA detection method for bit-patterned magnetic recording systems by computing a specific target by three readback sequences before estimating the SA value and detecting the SA amount happening in the system using an application of neural network namely multilayer perceptron. An error correction code, low-density parity-check, is applied, and its decoder outputs a log-likelihood ratio whose probability density distribution is examined. The simulation results show that the sliding window technique can significantly provide a better bit error rate performance.
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Reliability of PMN-PT piezoelectric material as an actuator for high density hard disk drive
(2018-07-02)
Wattananukulchai, Parinya
;
Isarakorn, Don
In the latest high-density hard disk drives (HDDs), the piezoelectric actuator of head gimbal assembly (HGA) is the key technology for precisely positioning the magnetic head. To increase HDD's areal density, a smaller track pitch and a faster spindle speed should be used but the faster the spindle rotates the larger the disturbance is. Hence, a newer PMN-PT piezoelectric actuator is needed to overcome the displacement bandwidth limitation restricted by the current PZT piezoelectric actuator. This paper investigated the reliability and performance of PMN-PT piezoelectric single crystal that was implemented on the a commercial HGA for the first time in an experiment. The objectives were to ensure that PMN-PT would not crack during the HDD assembly process and the performance of HDD equipped with this material was still reliable under thermal degradation. From the experiments on a prototype HGA, it was found that PMN-PT had a high degradation temperature of 150<sup>0</sup>C and was 2 times harder than PZT piezoelectric.
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Performance evaluation using laser doppler vibrometer sensing technique on advanced lead magnesium niobate-lead titanate piezoelectric-material-based microactuator for hard drive head
(2018-01-01)
Wattananukulchai, Parinya
;
Isarakorn, Don
This paper presents a microactuator for a dual-stage actuator (DSA) of hard disk drive (HDD) based on a lead magnesium niobate-lead titanate (PMN-PT) piezoelectric material and a comparative evaluation of its performance versus that of a traditional lead zirconate titanate (PZT) microactuator using the laser Doppler vibrometer (LDV) sensing technique. PZT microactuator technology has commonly been implemented in the read/write (R/W) magnetic head of HDD. It has a significant function, that is, it moves the magnetic head rapidly and accurately. In order to achieve both accurate positioning control on data tracks and high-speed access across another data track, advanced high-performance actuators and servo control technologies are necessary. An actuator with a wide stroke travel range is essential for HDD as it gives a high-speed access performance. In this study, we focused on comparing the proposed dual-stage PMN-PT head-based actuator with the existing PZT actuator that were mounted on a commercial head gimbal assembly (HGA) using an LDV to determine whether the proposed device could be a worthy replacement of the traditional PZT microactuator. Our experimental results show that the proposed PMN-PT microactuator provided more than twofold improvement in the stroke travel of the R/W magnetic head. Moreover, its dynamic behavior was suitable for assembling a high-density HDD in the future for big data storage without any needs to redesign the HGA nor to costly invest in new assembling machines in a production line. The comparative data of dynamic and static behaviors of PMN-PT versus PZT obtained in this study may be put to good use by sensor designers. Moreover, for many cyber-physical system designers, our data may make them take interest in PMN-PT as a better-performing sensor and an actuator for their systems.
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A comparative study based on classical and newer piezoelectric materials based unimorph actuators for Hard Disk Drive
(2017-02-08)
Wattananukulchai, Parinya
;
Isarakorn, Don
The piezoelectric actuator technology for moving the read-write head of Hard Disk Drive (HDD) is very important and widely used. Advanced high-performance technologies for the actuator and servo control are required in order to achieve not only accurate positioning control on data tracks but also high-speed access onto another data track. There is strong demand for hard disk drives with high-speed access performance, which generally requires actuators with a wider servo bandwidth. This paper focuses on the comparative piezoelectric materials based unimorph actuators with classical piezo (Poly crystalline PZT) and newer piezo (Single-crystalline PMN-PT) ceramics. The advantages of piezoelectric materials in terms of mechanical and electrical characteristics aiming at a useful compromise performance displacement and resonant frequency are studied and analyzed.

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