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... offered unprecedented random-access storage to 5 million characters each of 7-bit. These early prototypes had the heads of the hard disk in contact with the disk sur- face. This was done to allow the low-sensitivity ... center. The prevalent trend in hard disk design is towards smaller hard disks with in- creasingly larger capacities. This implies that the track width has to be smaller, which leads to lower error tolerance ... tighter regulation in the control of the servomechanism. To read (or write) the data reliably from (or to) the disk, the absolute track-following error with respect to the target track center,...

Ngày tải lên: 14/12/2013, 19:15

... transform the system P into the special coordinate basis as given by Theorem 3.1. To all submatrices and transformations in the special coordinate basis of P , we append the subscript P to signify their ... from to has an - norm equal to , i.e. . It is clear to see from the definition of the -norm that, in order to have a finite , the following must be satisfied: (3.59) which is equivalent to the existence ... and in the second stage a state estimator is designed. The estimator, otherwise called an ob- server or filter, is traditionally designed to yield the least mean square error estimate of the state...

Ngày tải lên: 14/12/2013, 19:15

... mode to the other, will be presented in the next subsection together with the stability analysis of the closed loop comprising the given plant and the MSC control law. In what follows, we show the ... and is referred to as the acceleration dis- count factor, and is the size of the linear region. Since the linear portion of the curve must connect the two disjoint halves of the nonlinear portion, ... on the feedback gains and the linear region to guarantee the continuity of the function . It was proved by Workman [30] that (4.31) The control zones in the PTOS are shown in Figure 4.4. The...

Ngày tải lên: 14/12/2013, 19:15

... commonly accepted in the literature (see, e.g., [86]), we define the settling time to be the total time that it takes for the control output to enter the region of the target reference. The following ... and is to be chosen to improve the performance of the closed-loop system. We have the following result. Theorem 5.16. Consider the given discrete-time system in Equation 5.136. Then, there exists ... function changes from to as the tracking error approaches zero. At the initial stage, when the controlled output, , is far away from the final set point, is small and the effect of the nonlinear part on the overall...

Ngày tải lên: 14/12/2013, 19:15

... systems have to ensure that the PES is kept to a minimum. Having deviations that are above the tolerance of the disk drive would result in too many read or write errors, making the disk drive unusable. ... model for the dual-stage actuator. Since the VCM actu- ator and the microactuator are decoupled, we need to identify two separate models for the VCM actuator and for the microactuator. A Maxtor dual-stage ... whereas the con- trol input to the microactuator is within V. 2. The displacement of the microactuator does not exceed 1 l um. Moreover, it has to settle down to zero in the steady state so that the...

Ngày tải lên: 14/12/2013, 19:15

... directly into the VCM driver to drive the coil. In order to simplify our analysis, we assume that the physical system has the fol- lowing properties: i) the permanent magnet is constant; and ii) the ... follows: N N sgn N N sgn N (9.1) where is the friction force, N is the normal force, i.e. the force perpendicular to the contacted surfaces of the objects, is the external force applied to the object, is the relative moving ... piezoelec- tric coefficients; is the input voltage that generates excitation forces in the actua- tor system. The variable is the displacement of the actuator and is also the only measurement we can...

Ngày tải lên: 14/12/2013, 19:15

... by (11.4) with represents the variation of the resonance modes of the actual actuators whose resonant dynamics change from time to time and also from disk to disk in a batch of million drives. Note that many new hard ... variance ( l um) . The problem is to design a controller such that when it is applied to the VCM actuator system, the resulting closed-loop system is asymptotically stable and the actual displacement of the ... the actuator, i.e. , tracks a reference l um. The overall design has to meet the following specifications: 1. the overshoot of the actual actuator output is less than 5%; 2. the mean of the steady-state...

Ngày tải lên: 14/12/2013, 19:15

... control of a disk drive actuator. IEEE Trans Magn 1994; 30:4224–6. 143. Xiong Y, Weerasooriya S, Low TS. Improved discrete proximate time optimal controller of a disk drive actuator. IEEE Trans ... for hard disk drives. Proc 24th IEEE Ind Electron Soc Ann Conf; Aachen, Germany; 1998. p. 1405–10. 157. Hernandez D, Park SS, Horowitz R, Packard A. Dual-stage track-following design for hard disk ... control for hard disk dual-stage servo systems. IEEE Trans Magn 2001; 37:949–54. 161. Li Y, Horowitz R. Track-following controller design of MEMS based dual-stage servos in magnetic hard disk drives....

Ngày tải lên: 14/12/2013, 19:15

... required to bring these patients to target is indicative of higher resis- tance. Discerning whether beta-cell exhaustion, or events secondary to the glucocorticoid therapy, contributed to the low ... the authors’ data, the issue becomes whether the low C-peptide levels in the RF+CVF group are indicative of a lower level of insulin resistance (Preissig and Rigby’s argu- ment), or whether the ... required longer, and at times up to 50% more, exogenous insulin to normalize glucose. Using the values reported, one could argue that the beta-cell had sufficient capacity to meet a peak demand of 0.13...

Ngày tải lên: 13/08/2014, 16:20

... by the file system. The start time corresponds to the moment when the disk driver gives the request to the disk, and the finish time corresponds to when the “request completed” interrupt fires. The ... SCSI, the cost of the low-level protocol for acquiring control of the bus is on the order of a few microseconds if the bus is idle. The SCSI protocol also allows a disk drive to disconnect from the ... architectures, there was no buffering in the disk drive itself. As a result, if the disk was ready to transfer data to a host whose interface was not ready, then the disk had to wait an entire...

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