硬盘自伺服刻写中径向误差特性研究

伺服信息刻写的效率是制约硬盘工业生产的瓶颈。自伺服刻写方法能够极大提高硬盘伺服信息的生产效率,但其中的径向误差累积过程会严重影响自伺服刻写产生的伺服信息的质量。本文分析了自伺服刻写过程的机理及模型,从中找出了径向误差产生的过程和原因,并提出了减小径向误差累积的办法。实验表明,该方法能够很好地抑制径向误差的生长。     

自伺服刻写中磁头OTC性能研究

定量分析磁头在整个盘片上的磁道偏移能力对自伺服刻写中参考值的确定十分重要.本文分析影响磁头磁道偏移能力的因素,其中重点讨论弯曲角对边界擦除带的作用以及由此对磁头道偏移能力的影响.在实验部分提出一种新方法,通过这种方法可以获得磁头飞过整个磁盘表面的磁头写入宽度和读取宽度,磁头道偏移能力.实验数据表明随着弯曲度的变化边界擦除带对磁头磁道偏移能力影响较大,弯曲度还造成磁头内外径磁道偏移能力的不一致性.     

硬盘自伺服刻写模型特性研究

自伺服刻写是解决伺服信息刻写问题的良好方案.详细讨论了自伺服刻写模型及其特点,指出定位准确度是衡量自伺服刻写方案好坏的重要指标.设计了3种控制器来控制自伺服刻写过程,实验数据表明了自伺服刻写中定位准确的重要性.重点指出鲁棒控制器能够很好地抵御外部扰动,保障自伺服刻写过程的精确度.     

磁盘伺服信息非脱机校验方法及实现

随着存储密度的不断提高,磁盘生产过程中伺服刻写及校验的时间消耗愈来愈大,伺服刻写及校验已成为影响磁盘生产质量和效率的瓶颈问题。为此提出了一种新的磁盘伺服信息校验方法-伺服刻写机内的非脱机校验。该校验方法将磁盘驱动器内部的信号处理机制用到伺服刻写机上,从而实现了在伺服刻写机内校验伺服信息。该方法避免了传统的伺服信息校验方法中磁盘盘片的重复装载和拆卸,减少了磁盘伺服刻写及校验在净房内的停留时间,降低了磁盘的生产成本;同时磁盘的质量也因手工操作的减少而得到显著提高。     

硬盘伺服刻写的新方法

本文提出了一种新的硬磁盘伺服刻写方法--螺旋伺服刻写法,推导了螺旋伺服运动模型,并做了性能分析。该方法首先将伺服初始信息以螺旋道的方式写入盘片,然后在后期由硬磁盘驱动器（HDD）自行将伺服信息补充完整,在保证伺服信息完整性的同时减少了关键资源的使用时间,缩短了伺服刻写时长,提高了生产效率,降低了生产成本。     

UHSIOV:一种磁盘伺服信息校验新方法

随着磁盘道密度的不断提高,刻写的磁盘伺服信息所需的校验时间已成为影响磁盘生产效率的瓶颈,为此提出了一种新的磁盘伺服信息校验方法-无人工介入磁盘伺服信息在线校验方法(Unmanned Harddisk Servo Info On-line Verifying method,UHSIOV),设计了校验系统的模型,并对相关功能模块及算法实现进行了详细阐述。实验表明,此校验方法在保证伺服校验完整性的同时,减少了伺服刻写机这一关键设备的使用时间,缩短了校验所需时长,且与传统校验方法相比做到了完全无人工介入校验。     

一种计算机视频监控系统的精确标定算法*

通过对整个计算机监控系统的误差源进行详细分析,将这些误差划分为制造误差、测量误差、计算误差三大类.在此基础上,提出了一种高精度的标定方法.此方法将标定过程明确划分为标定数据的提取、标定模型的建立、摄像机内外参数的计算和优化、畸变校正四个阶段.随着标定过程的推进,先后对图像像素量化噪声误差、图像坐标轴正交误差、不对心误差、镜头的径向畸变误差和切向畸变误差进行了修正.实验结果表明,标定方法非常精确,最后的标定总误差被控制在0.06个像素单位以内.     

一种径向基函数神经网络的参数求解方法

为了求解径向基函数神经网络的权值,首先分析了传统基于训练误差的方法,发现该方法容易造成数据过拟合,原因在于训练误差是风险函数的下偏估计;因此,文中提出采用缺一交叉验证得分代替训练误差,来实现无偏估计风险函数;实验对摩托数据与玻璃数据进行拟合,证实了基于缺一交叉验证的方法优于传统基于训练误差的方法,且所得到的径向基函数网络能够较光滑地拟合数据,不会造成过拟合.     

硬盘常见故障有哪些?

硬盘常见故障主要有硬盘坏道和零磁道故障等。其中硬盘坏道又分为逻辑坏道和物理坏道两种,前者为软坏道,通常为软件操作或使用不当造成的,可用软件修复;后者为真正的物理性坏道,它表明你的硬盘磁道上产生了物理损伤,只能通过更改硬盘分区或扇区的使用情况来解决。下面具体分析一下。1.逻辑坏道:就是“软坏道”,是由软件安装或使用错误造成的,一般对硬盘本身不会造成太大的危害。2.物理坏道:由于磁头和磁盘间的间隙仅有0.015～0.025微米,间隙非常小,硬盘在运输途中如果受到强烈颠簸,就可能使硬盘产生物理坏道。除此以外,人为的碰撞也会使一块…     

基于复合RBFNN的数字温度传感器误差补偿方法

数字温度传感器存在零点误差与非线性误差,需要进行误差补偿.提出了一种复合径向基函数神经网络(CRBFNN)的数字温度传感器误差补偿方法:首先根据数字温度传感器的误差特征,构造两个相互独立的子RBFNN网络,获得两个独立的冗余补偿值;然后根据特征阈值、数字温度传感器的输出估计器和权值调节器,获得复合RBFNN输出融合权值...     

An iterative learning approach to compensation for the servo track writing error in high track density disk drives

The servo tracks of hard disk drives are written at the time of manufacture with the equipment of servo track writer. The disk vibrations or head fluctuations during servo track writing process give rise to servo track writing error. The servo track writing error may cause some critical errors during data writing operation. In this paper, we propose a new correction algorithm for the servo track writing error based on the iterative learning control technique. The estimate of the servo track writing error is constructed from the position error signal and updated iteratively at each disk rotation. Then, the estimate of servo track writing error is used to correct the position error signal in a feed-forward manner. Our correction algorithm is robust to system model uncertainties, computationally quite simple, and has fast convergence rate. Furthermore, we give a rigorous analysis for the convergence of our correction algorithm. In order to demonstrate the practical use of our work, we present some experimental results using a commercially available hard disk drive.     

MEMS存储设备的伺服设计

和硬盘相似,基于MEMS的存储设备读写数据时也采用伺服来定位.在分析MEMS存储设备固有特点的基础上,以硬盘的伺服原理为基础,提出了几种可行的伺服方式,分析并比较了各种伺服方式对数据布局、通道设计、服务时间和空间利用率的影响.结果表明,合适的伺服可以大幅度提高MEMS存储设备的性能.     

Linear actuator for precise track following

A new air bearing linear actuator with a Voice Coil Motor (VCM) was investigated for a precise head track following in an Hard Disk Drive (HDD) magnetic recording tester system. The actuator has a servo bandwidth of two times as wide as that of a conventional HDD, due to a high stiffness without any friction. A low-pass filter was introduced to precisely monitor the step response behavior by reducing the relatively large noise of the used optical fiber sensor. The effect of the low-pass filter was investigated comparing with the other method. Track following accuracy was also tested by using a conventional 2.5-inch hard disk drive. The head installed on the actuator could follow on a track by using Position Error Signal (PES) from the servo pattern. When a Double Metal In Gap (D-MIG) head of 4 μm track-width was loaded on a disk rotating at 4200rpm, the tracking error could be compressed down to one-twentieth of the track-width. The tested system did not show any azimuth error of head-tracking due to the linear motion. In conclusion, the air-bearing linear actuator is suitable for a precise track following mechanism of a spin-stand tester for an HDD system.     

Hinge pivot for disk drive

This paper discusses the findings of a hinge pivot for use in hard disk drives (HDD). The actuator assembly in a HDD is supported by a pivot cartridge and controlled by a servo system to perform seek and track following operations for data recording. The cartridge is composed of a pair of pre-loaded ball bearings. Due to the demand for thin hard disk drives and hence, the need to reduce the height of the actuator assembly, a hinge pivot is proposed to replace the set of bearings. The shaft of the pivot is connected to the sleeve with thin hinges made of ultra-high heat-resistant polyamide film, such as Upilex. Measurement showed that the hinge pivot did not exhibit the nonlinear effects during low frequency actuation, such was inherent for ball bearing pivots. Experiment also showed that at least a million life cycles can be achieved without any performance degradation.     

Dynamics simulation of MEMS device embedded hard disk drive systems

Currently, hard disk drives (HDD) use rotating disks to store digital data and magnetic recording heads are flying on the disk to read/write data. The recording heads are mounted on a slider–suspension assembly, which makes heads move from one track to another on the disk. The heads movement is controlled by close-loop feedback servo systems. It is well known that dynamic behaviors of head–slider–suspension-assembly (HSA) systems are of great influence on the track per inch capacity of HDD [1, 2]. As the problem is structurally complex, it is usually investigated using experimental methods or finite element simulation models [3]. Furthermore, the dual-stage servo system has been commonly considered as one promising solution to increase the servo bandwidth of the recording positioning system for high TPI HDDS. In particular, MEMS device embedded systems are superior to others in batch-fabrication. However, this dual-stage system has also resulted in more difficulties in predicting HDD dynamic performance. This paper presents the study of the problem using the macromodeling simulation approach. It applies efficient FEM based sub-structuring syntheses (SSS) [4] and fast boundary element method (BEM) approaches incorporated with system dynamics technology to investigate the dynamic characteristics of MEMS actuator embedded HSA systems for HDD.This research is funded by the Agency for Science, Technology and Research of Singapore, Strategic Research Program. Also, the authors would like to thanks Miss Jia Wenhui, who is a Research Student with ECE Department at National University of Singapore, Mr. Lim Boon Buan, the former research engineer with Data Storage Institute, for the MEMS actuator modeling and analytical work.     

Position error signal generation in hard disk drives based on a field programmable gate array (FPGA)

The position error signal (PES) in current hard disk drives is generated from the embedded servo data and used as the input for the track following controller. The servo pattern design and the decoding are both quite complicated in terms of the servo writing and servo detection, but they are important for the system dynamics study and track following controller design. In this paper, a novel scheme based on discrete fourier transformation (DFT) to decode the servo signal from a special magnetic servo pattern and generate the PES is proposed. In the scheme adjacent magnetic tracks with different frequencies are recorded to the disk and used as servo tracks to encode the position information. Simulation results show that the amplitudes at the two writing frequencies in the readback spectrum depend on the magnetic head position. The quadrature PES defined by the difference of the amplitudes is almost linear between the two adjacent tracks The simulation and off-line experimental results analysis agree with each other and prove the feasibility of this scheme. A real-time signal acquiring and processing system with a commercial field programmable gate array (FPGA) and ADC/DAC chips was built, and the proposed scheme was implemented in the FPGA to do the high-speed signal analysis. The magnetic head position information is extracted from the readback spectrum in the FPGA and transferred to a PC host for real-time graphic display using a labview interface. The system demonstrates an ability to generate the PES at 25 K samples per second with a resolution around 3 nm. The sampling rate can be enhanced further to 125 kHz if more servo sectors are written to the disk. This system provides a re-configurable research stage for studying the dynamic behavior of hard disk drives and for developing the control algorithm for track following.     

硬盘驱动磁头偏置误差检测算法的研究

在硬盘装配过程中,通常需要对磁头间的磁头偏置误差进行预校准,并实施有效的补偿措施以减少磁头切换时的寻址误差,提高读写效率。然而,由于剧烈震动或不当操作等因素的影响,校准好的磁头偏置可能偏离预校准值,从而导致硬盘寻址或读写性能的下降以及伺服启动时间的延长。提出了一种在硬盘正常启动过程中快速有效的磁头偏置的检测和补偿算法,设计了与磁盘扇区绑定磁头偏置滤波方案。实验表明此方法可以快速有效地识别磁头偏置,并启动相应的校准操作,提高了硬盘在剧烈震动后的伺服性能。