Logical sensors can only detect a state that is either true or false. Topology optimization of actuator arms in hard disk drives. The selfsensing microactuator forms a combined sensing and actuation mechanism. I know your problem quite well because i am now dedicated on the aerodynamic calculation of turbomachinery by use of actuator disk theory. As the recording track density increases in hard disk drives, the offtrack errorrejection capability of the servo controller must also be increased. To understand more about the performance of propellers, and to relate this performance to simple design parameters, we will apply actuator disk theory. Servo experiments for modeling of actuator and windage dynamics in a hard disk drive jie zeng and raymond a.
We will find that adding wake rotation will decrease the theoretical maximum. Froudes actuator disk theory provides a simple, 1dimensional approach to the problem of rotor modelling. A platter is a circular magnetic plate that is used for storing data in a hard disk. Actuator disc theory gives some understanding of the meridional throughflow in turbomachines of simple geometry and flow conditions, but its application to design and analysis is now quite limited. Actuation systems are the elements of control systems which are responsible for transforming the output of a microprocessor or control system into a controlling action on a machine or device.
The actuator disk theory revealed that the maximum power coefficient c p is governed by the betz limit of c p,max 0. Jeffers umited techologies corporation west palm beach, florida prepared for lewis research center under contract nas320060 nasa national aeronautics and space administration scientific and technical information branch 1981. Our experimental results show that both strategies are effective in. Semi actuator disk theory for compressor choke flutter j. Aug 01, 2015 actuator disc approach introduction in the following sections, the aerodynamic theory of the hawt is gradually developed, starting with the simple 1d momentum analysis of the actuator disc and followed by the more detailed analysis of the blade element theory.
Bending flutter in axialflow compressor by actuator disk. As time wore on, we developed better means of motion, like battering rams. Thrust loading and velocity are uniform over the disk. In late 1990, our research focused on vibration of hdd spindle motors with fluiddynamic bearings fdb.
Exploring the flow expansion causing the betz limit using the actuator disk theory. Actuation and thurst vector control systems include heritage technology for electrohydraulic, electromechanical and electrohydrostatic as well as new developments with modular components for the future of spaceflight. Vibration of hard disk drives mechanical engineering. Bending flutter in axialflow compressor by actuator disk theory. Wake modeling with the actuator disc concept sciencedirect. The battering ram could be considered the first actuator in history, since it creates motion in. Lutz pickelmann gmbh piezoelectric bending actuators disk translators bimorphs piezoelectric tubes. Blade element theory is combined with momentum theory to alleviate some of the. A case of metal frame for actuator production process. The general methods developed using actuatordisc theory are used to calculate the flow through the model stage and are compared with raillys theory, and with radial equilibrium solutions.
Instrumentation and control tutorial 2 electric actuators this is a stand alone tutorial on electric motors and actuators. Visual basic application for statistical process control. Rankine 1865, alfred george greenhill 1888 and robert edmund froude wikidata 1889. For lowspeed flows, actuator disk flutter models have been able to predict the onset of a singledegreeoffreedom bending flutter mode e. Direct velocity feedback and positive position feedback are used in this paper. The gyroscopic motion is particularly important to hdds, because it is a major source leading to readwrite errors. Rankine 1865, alfred george greenhill 1888 and robert edmund froude wikidata 1889 the rotor is modeled as an infinitely thin disc, inducing a constant velocity along the axis of rotation.
Then the power to the actuator coil, which drives the actuator arm, is reduced to zero and the actuator arm is released. In early 2000, our study turned to coupled vibration among an hdd housing, a spinning disk pack, and connecting bearings. A hard disk drive contains several platters that are mounted on the same spindle. Active vibration control of a microactuator for the hard disk. The disk is the third primary principal pressure boundary. We model the flow through the propeller as shown in figure 7.
We finally understood that we could use the items around us as tools to make life easier. This paper presents the selfsensing control of a microactuator for hard disk drives. We model the flow through the propeller as shown in figure 11. Armed with the following assumptions consider an ideal rotor as shown below. On the limitations of froudes actuator disc concept. All the heads are attached to a single head actuator, also called an actuator arm, that moves the heads around the platters. It is used to calculate the local forces on a propeller or windturbine blade. On completion of this tutorial, you should be able to do the following. This information will be used in the design of a fast shutter system made by salvaging the hddd actuator arm. Hard disk drives hdd not only offer an inexpensive way for data storage, but also enable various digital technologies ranging from computers to cloud computing. In fluid dynamics, the momentum theory or disk actuator theory is a theory describing a mathematical model of an ideal actuator disk, such as a propeller or helicopter rotor, by w. The sectional load is calculated with the blade element theory for a propeller of a sailplaine with a folding engine and the actuator disk is applied to investigate the effect of the jet to the elevator. A computer hard disk has many different components.
Request pdf an inconsistency in the actuator disc momentum theory the classical momentum theory for actuator discs with a constant normal load. How to use an external limit switch with a linear actuator. These components include the platter, the spindle, head, actuator arm, actuator axis, power connector, jumper block, ide connector, and the actuator. The platters rotate when the hard disk is performing readwrite operations. The topology of the grid maintains fluxes conservative through the disk. Marine power project froudes momentum theory for an. Developments of actuator disc theory 1055 term a this may be dealt with by normal well established actuator disc theory as summarized by hawthorne and horlock 1 who have shown that the tangential vorticity in the free spaces between actuator discs obeys the relationship deor r dpo 8 coo co do p do thus for freevortex flow, cor. Actuators are one of the key components contained in a robotic system. Hello select your address best sellers customer service new releases find a gift whole foods registry gift cards sell amazonbasics customer. Determination of wind turbine far wake using actuator disk. Older hard drives used a stepper motor actuator, which moved the heads based on a motor reacting to stepper pulses. Semiactuator disk theory for compressor choke flutter j. A hard disk drive hdd, hard disk, hard drive, or fixed disk is an electromechanical data storage device that uses magnetic storage to store and retrieve digital data using one or more rigid rapidly rotating platters coated with magnetic material. I think its easy to programme by yourself with the actuator disk theory.
Modern hard drives use a voice coil actuator, which controls the movement of a coil toward or. In this paper a new actuator disk is presented which is consistent with the classical model of momentum theory of a zero thickness surface which imposes a discontinous pressure jump to the flow. Hard disk drive, trackfollowing control, quantitative feedback, robust control. The actuation efficiency measure alan bowling oussama khatib robotics laboratory department of computer science stanford university, stanford, ca 94086 abstract this article presents a new performance meamre, the actuation eficiency, which describes isotropy in accel. A method for controlling the velocity of an actuator arm in a hard disk drive includes moving the actuator arm to an inner limit or outer limit of motion. Jul 17, 2009 some toms hardware readers may remember the company. An inconsistency in the actuator disc momentum theory. It is often made of aluminum, glass substrate or ceramic. The nonlinear actuator disk method as applied to open and. Hello select your address best sellers customer service new releases find a gift whole foods registry gift cards sell amazonbasics customer service new releases find.
Introduction nowadays, the hard disk drive is the main storage device in the computer system. The positions of the actuator planes are illustrated in figs. Actuator disc methods applied to wind turbines by robert mikkelsen dissertation submitted to the technical university of denmark in partial fulllment of the requirements for the degree of doctor of philosophy in mechanical engineering fluid mechanics department of mechanical engineering technical university of denmark june, 2003. Bends in the flexible cable connected to the actuator arm can cause the actuator arm to move toward the outer limit of. The general methods developed using actuator disc theory are used to calculate the flow through the model stage and are compared with raillys theory, and with radial equilibrium solutions. Semiactuator disk theory for compressor choke flutter. Many portable devices such as laptops, tablets, and music players prefer the data storage with higher capacity while its size needs to be smaller. Conner actually patented a hard drive design that utilized dual actuators, that is, a hard drive with two sets of readwrite units.
All of these accessories to the computer hard disk are necessary in order for the hard disk to read, store, and record data. The part of a hard disk to which the readwrite arms attaches. The first is the aforementioned nonlinear and semianalytical actuator disk method. Blade element momentum theory is a theory that combines both blade element theory and momentum theory. There is a lot of material discussing the rotational speed of the magnetic disk in hdd but not about the rotational speed of actuator arm. Let us summarize the assumptions the actuator disk model. Control design and implementation of hard disk drive servos. Journal of advanced mechanical design, systems, and manufacturing vol. Developments of actuator disc theory for compressible flow. Media in category actuator disk theory the following 18 files are in this category, out of 18 total. Determination of wind turbine far wake using actuator disk rodeyna amer, ivan dobrev, fawaz massouh to cite this version. Journal of advanced mechanical design, systems, and. How to use an external limit switch with a linear actuator an external limit switch is a very handy and cost effective means of controlling the travel of a linear actuator. The tutorial is of interest to any student studying control systems and in particular the ec module d227 control system engineering.
Internal cylinder position feedback devices standard lrt 7500 series pictured custom actuator products, inc. I dont think cfx is adaptable while you solve your problems using acutator disk theory. We further assume that the actuator disk be stationary no rotation and that the uniform wind entering the streamtube does not change in time steady. In this dissertation, the design of servo control algorithms is investigated to produce highdensity and costeffective hard disk drives hdds. A comparison of actuator disk and actuator line wind turbine models and best practices for their use conference paper pdf available january 2012 with 1,835 reads how we measure reads. For lowspeed flows, actuator disk flutter models have been able to predict the onset of. The effects of flow separation are included in the model through rotorloss and deviationangle corre lations. The high rejection capability is achieved by increasing the servo bandwidth. Tels, voor een commissie aangewezen door het college van dekanen, in het openbaar te verdedigen op vrijdag 8 februari om 16. In rotor disk theory, on the contrary, we will discover that rotor power is generated through rotor torque and the angular momentum in the wake via a combination of axial and angular induction factors. The actuator disk theory generated the rotor power via the rotor thrust and the axial induction factor a. Actuator disk theory applications include propellers,rotors and ducted fans.
What are the typical actuation speeds of the actuator in hdd. The second is based on the introduction of an actuator disk model in a cfd package describing the effects of the rotor through radial profiles of blade forces distributed over a disk surface. As hdds increase their data density and spin speed, hdd vibration becomes more and more important. Some actuatordisc theories for the flow of air through an. The mathematical model of the disk theory using the simulation program of matlab is. The microactuator uses a pzt actuator pair installed on the suspension assembly. In order to sustain the continuing increase of hdd data storage density, dualstage actuator servo systems using a secondary microactuator have been developed to improve the. In this article, we will go over how to use an external limit switch with a linear actuator. Energy procedia 24 2012 385 a 392 18766102 2012 published by elsevier ltd. Pdf a comparison of actuator disk and actuator line wind.
Us6683743b2 method for controlling the velocity of an. For example, we may have an electrical output from the controller which has to be transformed into a linear motion to move a load. Missionspecific actuation mechanisms for solar array deployment, antenna pointing and special instruments. Trackfollowing controller for hard disk drive actuator using quantitative feedback theory takat benjalersyarnon1, withit chatlatanagulchai2 control of robot and vibration laboratory, faculty of engineering, kasetsart university. Apr 24, 2012 bendsoe mp, sigmund o 2003 topology optimization, theory, methods and applications. The flow state just upstream of the rotor plane forms the socalled inflow condition for. Some toms hardware readers may remember the company.
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