Head positioning servo design for the IBM 3344/3350 disk files

The 3344/3350 disk files have significantly increased both the recording areal density and total storage capacity per spindle in comparison to previous disk file products, such as the 3340. Parameters directly related to the head positioning systems are compared. Three areas of the head positioning servo system that required design changes for increased performance are described: (1) the encoding used on the servo disk to obtain position information, (2) the compensation technique employed in the track following controller to reduce steady state positioning error and (3) implementation of the phase plane trajectory for improved accuracy and settling as well as decreased access time.     

Human-centric sensing

The first decade of the century witnessed a proliferation of devices with sensing and communication capabilities in the possession of the average individual. Examples range from camera phones and wireless global positioning system units to sensor-equipped, networked fitness devices and entertainment platforms (such as Wii). Social networking platforms emerged, such as Twitter, that allow sharing information in real time. The unprecedented deployment scale of such sensors and connectivity options ushers in an era of novel data-driven applications that rely on inputs collected by networks of humans or measured by sensors acting on their behalf. These applications will impact domains as diverse as health, transportation, energy, disaster recovery, intelligence and warfare. This paper surveys the important opportunities in human-centric sensing, identifies challenges brought about by such opportunities and describes emerging solutions to these challenges.     

基于环形红外阵列的移动机器人自动跟随系统

为了实现在室内空旷环境中跟随机器人对移动目标物的定位和动态跟踪,设计了一种基于环形红外阵列的移动机器人自动跟随系统.利用具有主动式环形大视场的测距罗盘作为环境感知传感器.测距罗盘由数个红外测距传感器组成周向阵列,实现对360°环向10～80 cm范围内移动目标物的二维定位,使跟随机器人可以快速确定其与移动目标物之间的距...     

High track density for magnetic disk drives with an "Embedded servo" positioning system

The CII-HB "Embedded servo" original technique for disk drive units (such as the D 160) allows operation at high track densities ( 800 TPI) and fast access time. The overall information needed for head displacement and positioning is provided by the data head itself, without any other transducer. Servo transitions, written between the data sectors, are arranged to provide gain information, track logical address, and fine position. This information is used by a microcomputer program to move the head rapidly to the desired track and to lock it in position within an instantaneous error of less than 3 μm (120 μm inches). Practical results are presented and compared with a theoretical model. Limitations and improvements are discussed.     

Position sensing for high track density recording

Progress towardhigher digital areal densities is related to the data track position sensing accuracy obtainable in future disk drives. In most systems available, position sensing is done remotely from the data track and subject to different dimensional stability conditions. To obtain higher track densities, position sensing reference information must be moved near the data track. Several techniques are available to embed reference information in the data track. All the techniques described have one of two basic principles of operation. One method uses comparison of reference signal amplitudes and the second method uses arrival time differences of reference signals. The time method is relatively unknown but offers the designer some new alternatives. This paper describes an overview of several methods. Relationships are derived to relate the influence of noise on both basic methods. Linearity, relative hardware simplicity, and track capture range are also discussed. It is our conclusion that the Amplitude or Tri-Bit method offers the greatest hardware simplicity, but is limited by noise and non-linearity at high track densities. The time dependent or Chevron method requires two data channels, but offers a relatively higher noise immunity, better linearity, and higher data capacity.     

基于扩展卡尔曼滤波的轮式移动机器人定位技术

针对单一传感器或现有多传感系统在信息传递提取上的不足,应用一种信息融合方法,对机器人进行相对定位与绝对定位的融合分析,得出机器人的最优位置信息,最终实现了移动机器人的精确定位。首先,采用码盘、陀螺仪进行机器人相对定位,采用激光雷达进行机器人绝对定位;其次,建立环境地图、传感器及机器人运动模型;最后,以扩展卡尔曼滤波作为多传感器融合技术,建立多传感器信息融合模型,实现精确定位。     

Tubular 3D Resistive Random Access Memory Based on Rolled‐Up h‐BN Tube

Due to their advantages compared with planar structures, rolled‐up tubes have been applied in many fields, such as field‐effect transistors, compact capacitors, inductors, and integrative sensors. On the other hand, because of its perfect insulating nature, ultrahigh mechanical strength and atomic thickness property, 2D hexagonal boron nitride (h‐BN) is a very suitable material for rolled‐up memory applications. In this work, a tubular 3D resistive random access memory (RRAM) device based on rolled‐up h‐BN tube is realized, which is achieved by self‐rolled‐up technology. The tubular RRAM device exhibits bipolar resistive switching behavior, nonvolatile data storage ability, and satisfactorily low programming current compared with other 2D material‐based RRAM devices. Moreover, by releasing from the substrate, the footprint area of the tubular device is reduced by six times. This tubular RRAM device has great potential for increasing the data storage density, lowering the power consumption, and may be applied in the fields of rolled‐up systems and sensing‐storage integration.     

Precision pointing of imaging spacecraft using gyro-based attitude reference with horizon sensor updates

Remote sensing satellites are required to meet stringent pointing and drift rate requirements for imaging operations. For achieving these pointing and stability requirements, continuous and accurate three-axis attitude information is required. Inertial sensors like gyros provide continuous attitude information with better short-term stability and less random errors. However, gyro measurements are affected by drifts. Hence over time, attitudes based on the gyro reference slowly diverge from the true attitudes. On the other hand, line-of-sight (LOS) sensors like horizon sensors provide attitude information with long-term stability. Their measurements however are affected by the presence of random instrumental errors and other systematic errors. The limitations of inertial and line-of-sight sensors are mutually exclusive. Hence, by optimal fusion of attitude information from both these sensors, it is possible to retain the advantages and overcome the limitations of both, thereby providing the precise attitude information required for control. This paper describes an improved earth-pointing scheme by fusion of the three-axis attitude information from gyros and horizon sensor roll and pitch measurements along with yaw updates from the digital sun sensor. A Kalman Filter is used to estimate the three-axis attitude by online estimation and corrections of various errors from the sensor measurements. Variations in orbit rate components are also accounted for using spacecraft position and velocity measurements from the satellite positioning system. Thus precise earth-pointing is achieved     

基于最大似然估计的辐射噪声源近场定位方法性能分析

如何利用较少的阵元个数得到比较理想的空间分辨力,准确找到噪声源位置,一直是人们比较关心的问题,因此介绍了基于最大似然估计的辐射噪声源近场定位方法,并利用遗传算法寻求最大似然估计的全局最优解,从而实现噪声源近场定位,其具有比常规聚焦波束形成更高的空间分辨力,且可以有效实现相干声源近场定位。通过计算机仿真详细分析了信噪比、测量距离及基阵孔径对本文算法定位性能的影响,说明了仅利用小孔径基阵就可实现辐射噪声源近场高分辨定位,最后通过湖试实验验证了该方法的有效性,具有一定的工程应用价值。     

Digital processing of dual-frequency servo burst in hard disk drives

The trend of increasing areal density, i.e., the number of bits recorded in unit area of the media, continues in the hard disk drive (HDD) industry. This growth is sustained by increasing both the track density and bit density. The track density that can be achieved in a drive depends on many factors such as the dimensions of read/write head and the performance of the head positioning servomechanism. The higher the servo bandwidth, the better the precision achieved in controlling the position of the head. Most of the drives use an embedded servo scheme, which puts a physical constraint on the frequency at which the position error is sampled, and hence, on the achievable bandwidth. The need for a better position error sensing (PES) scheme is the motivation behind exploring alternative methods of servo encoding. This paper addresses different aspects of decoding position error from the dual-frequency servo bursts. It is shown, using both simulation and experimental results, that the proposed scheme offers a feasible solution for generating the PES signal in high-performance HDD.     

Self-contained, fully integrated biochip for sample preparation, polymerase chain reaction amplification, and DNA microarray detection

A fully integrated biochip device that consists of microfluidic mixers, valves, pumps, channels, chambers, heaters, and DNA microarray sensors was developed to perform DNA analysis of complex biological sample solutions. Sample preparation (including magnetic bead-based cell capture, cell preconcentration and purification, and cell lysis), polymerase chain reaction, DNA hybridization, and electrochemical detection were performed in this fully automated and miniature device. Cavitation microstreaming was implemented to enhance target cell capture from whole blood samples using immunomagnetic beads and accelerate DNA hybridization reaction. Thermally actuated paraffin-based microvalves were developed to regulate flows. Electrochemical pumps and thermopneumatic pumps were integrated on the chip to provide pumping of liquid solutions. The device is completely self-contained: no external pressure sources, fluid storage, mechanical pumps, or valves are necessary for fluid manipulation, thus eliminating possible sample contamination and simplifying device operation. Pathogenic bacteria detection from approximately milliliters of whole blood samples and single-nucleotide polymorphism analysis directly from diluted blood were demonstrated. The device provides a cost-effective solution to direct sample-to-answer genetic analysis and thus has a potential impact in the fields of point-of-care genetic analysis, environmental testing, and biological warfare agent detection.     

Multichannel Temperature Sensing by Differential Coherence Multiplexing

The method of differential coherence multiplexing is demonstrated for multichannel temperature sensing. The idea of the method is to introduce into the conventional coherence-multiplexed sensor array a chain of stable etalon interferometers connected to the interrogating interferometer in parallel to the sensor chains. Optical delays of sensor interferometers are obtained from the phase shift of the interference maximums of the etalon and sensor coherence peaks. The technique is inherently insensitive to low-frequency phase noise in the interrogating interferometer and does not require any means for measurement of the optical path difference of the interrogating interferometer. Multiplexed temperature sensing is demonstrated in a chain of four extrinsic Fabry–PÉrot temperature sensors in the range of 400$^circ hboxC$with a root-mean-square noise of 0.005$^circ hboxC$. Theoretical estimations show a possibility of increasing the dynamic range to the units of$10^5$.     

Semiconductor self-assembled quantum dots: present status and future trends

Progress in controlling the size, shape, and composition of quantum dots (QDs) as well as their positioning will be crucial to further advances in the fields of quantum information and device applications. The growth of QDs into lattices using controlled positioning of the QD nucleation centers is a possible method. QD positioning is also much needed for further development of QD microcavities and photonic-crystal based devices that are used for quantum information applications. This article discusses the prospects for progress in these fields that may be realized if a better control over the positioning and self-positioning of quantum dots is achieved.     

Adaptive compensation for position error signal nonlinearity

The magnetoresistive (MR) magnetic head is a poor positioning transducer for a disk file's servo control system because its positioning response is nonlinear with radial displacement. This paper shows how the MR head's poor positioning properties are alleviated by a self-adjusting adaptive algorithm that allows a disk file to linearize its own servo position error signal (PES). The adaptive linearizer uses a nonlinear state estimator whose nonlinearity adjusts to match the nonlinearity of the PES. As the match between the two nonlinearities adaptively improves, the state estimator gives increasingly accurate estimates of the true actuator position     

Reliable mechatronic indicator for self-powered liquid sensing toward smart manufacture and safe transportation

In the era of industry 4.0, mechanical indicators are in great demand for providing reliable information in a harsh environment with a self-powered signal transmission ability for connecting into a centralized automatic control network of ships, trucks, and factories. In this work, based on the principle of nanogenerator, we report a block-inserting mechatronic (BIM) panel employed as not only a mechanical indicator with long operation lifetime, versatile adaptability, and improved reliability under harsh working conditions, but also an active electronic sensor for self-powered liquid information indicating and sensing. The methodology of block-inserting assembly significantly simplifies the processing costs and difficulties, which facilitates length-customization of the whole device. When equipped with the BIM panel, computer control and monitoring systems realize wireless control and real-time monitoring of liquids in miscellaneous industrial applications. This work lays the foundation of nanogenerator-based sensors applied in industrial systems, which will strongly promote the progress of industry 4.0, smart cities, and transportation.     

An adaptive filter for the processing of position error signal in disk drives

A novel circuit used to process analog position error information in a disk drive head-positioning servo system drastically reduces noise in the signal and compensates for effects due to insufficient position sample rate at high carriage velocities. The processed signal does not suffer from envelope droop at high carriage velocities, and lends itself well to track counting algorithms. Because the filter's bandwidth and low-frequency gain are controlled by carriage velocity information, the filter characteristics adapt to environmental conditions for near optimal reduction of noise.     

On‐Chip Spiral Waveguides for Ultrasensitive and Rapid Detection of Nanoscale Objects

Ultrasensitive and rapid detection of nano‐objects is crucial in both fundamental studies and practical applications. Optical sensors using evanescent fields in microcavities, plasmonic resonators, and nanofibers allow label‐free detection down to single molecules, but practical applications are severely hindered by long response time and device reproducibility. Here, an on‐chip dense waveguide sensor to monitor single unlabeled nanoparticles in a strong optical evanescent field is demonstrated. The spiral nanowaveguide design enables two orders of magnitude enhancement in sensing area compared to a straight waveguide, significantly improving the particle capture ability and shortening the target analysis time. In addition, the measurement noise is suppressed to a level of 10^?4 in the transmitted power, pushing the detection limit of single particles down to the size of 100 nm. The waveguide sensor on the silicon‐on‐isolator platform can be fabricated reproducibly by the conventional semiconductor processing and compatible with surface functionalization chemistries and microfluidics, which could lead to widespread use for sensing in environmental monitoring and human health.     

Nonrepeatable Run-out Rejection Using Online Iterative Control for High-Density Data Storage

The spectra of disturbances and noises affecting precise servo positioning for ultrahigh-density storage in future hard disk drives are time-varying and remain unknown. In this paper, we propose an online iterative control algorithm that sets the measured position error signal (PES) into the servo system to achieve high track densities by minimizing the square of the H₂-norm of the transfer function from nonrepeatable run-out (NRRO) disturbances to the true PES. It is not necessary to solve any algebraic Riccati equations and linear matrix inequalities. The algorithm constructs an online repeatable run-out estimator to extract NRRO components for gradient estimates, thereby preventing the controller parameters from being trapped in a local minima. Experimental results on a PC-based servo system for a spinstand show an improvement of 22% in 3sigma NRRO and suppression of baseline NRRO spectrum     

A Ferrofluidic Inclinometer in the Resonant Configuration

In this paper, an innovative inclinometer exploiting ferrofluids is presented. The device consists of a glass pipe filled with deionized water and a drop of ferrofluid, a coil generating a retaining force on the ferrofluidic drop, a couple of sensing coils detecting the ferrofluidic mass position, and two exciter coils moving the ferrofluidic drop back and forth inside the water at the resonance frequency of the whole system. The device exhibits an intrinsic robustness against inertial shocks. The resonant operation mode represents the main novelty with respect to previous realizations of the ferrofluidic inclinometer presented by the authors. This strategy allows for improving the performances of the inclinometer also in terms of mechanical sensitivity. This paper will focus on the design and experimental characterization of the resonant inclinometer, showing improvements achieved by the resonant configuration with respect to the previous “static implementation” without the exciter coils.      

Small‐Scale Biological and Artificial Multidimensional Sensors for 3D Sensing

A vast majority of existing sub‐millimeter‐scale sensors have a planar, 2D geometry as a result of conventional top‐down lithographic procedures. However, 2D sensors often suffer from restricted sensing capability, allowing only partial measurements of 3D quantities. Here, nano/microscale sensors with different geometric (1D, 2D, and 3D) configurations are reviewed to introduce their advantages and limitations when sensing changes in quantities in 3D space. This Review categorizes sensors based on their geometric configuration and sensing capabilities. Among the sensors reviewed here, the 3D configuration sensors defined on polyhedral structures are especially advantageous when sensing spatially distributed 3D quantities. The nano‐ and microscale vertex configuration forming polyhedral structures enable full 3D spatial sensing due to orthogonally aligned sensing elements. Particularly, the cubic configuration leveraged in 3D sensors offers an array of diverse applications in the field of biosensing for micro‐organisms and proteins, optical metamaterials for invisibility cloaking, 3D imaging, and low‐power remote sensing of position and angular momentum for use in microbots. Here, various 3D sensors are compared to assess the advantages of their geometry and its impact on sensing mechanisms. 3D biosensors in nature are also explored to provide vital clues for the development of novel 3D sensors.