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Author: search.filters.author.Konghuayrob, PoomSubject: search.filters.subject.H∞ loop shaping

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    Low order robust ν-gap metric H∞ loop shaping controller synthesis based on particle swarm optimization
    (2017-12-01)
    Konghuayrob, Poom
    ;
    Kaitwanidvilai, Somyot
    The strong demand of the data storage capacity has been increasing significantly. According to the heat-assisted magnetic recording (HAMR) technology, the demand trend of hard disk drive (HDD) is predicted that the areal density will be achieved 10 Tbit/in<sup>2</sup> before the year 2020. High areal density results in a narrow track pitch which is quite sensitive to the external disturbance including the measured noise. This point is the benchmark problem of the high precision controller design for controlling the HDD servo mechanism. Moreover, the systematic uncertainties have to be taken into consideration in controller design procedure as well. The alternative robust ν-gap metric related to H<inf>∞</inf> loop shaping is proposed in this paper to stabilize a voice coil motor in HDD under the uncertainty condition. The potential particle swarm optimization (PSO) is adopted to minimize the gap between the plant with H<inf>∞</inf> controller and the plant with specified 3 controller orders. Instead of using the conventional H<inf>∞</inf> controller with high order with a complicated structure, this paper applies the proposed lower controller order based on ν-gap which is more appropriate implement in the actual application. The performance and robustness of both controllers are compared in the simulation studies. The results confirm the similar characteristics of both controllers in terms of performance tracking and disturbance rejection. Furthermore, the system stability index called stability margin with 0.472 and system perturbations testing condition also emphasizes the robustness and effectiveness of the proposed controller.
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    Particle swarm optimization based specified order robust-gap H∞ loop shaping controller design
    (2017-01-01)
    Konghuayrob, Poom
    ;
    Kaitwanividvilai, Somyot
    The demand of data storage capacity in hard disk drive is expected to increase significantly which the areal density will achieve 10 Tbit/in<sup>2</sup> in the near future. An increase of high areal density leads to the reduction of distance per data tracks. Due to the narrow track pitch, hard disk drive system is easily sensitive to the disturbance and noise. This is the benchmark problem for controlling the high precision servo mechanism. The alternative robust loop shaping based v-gap metric is proposed to synthesize the optimal controller for stabilizing a voice coil motor in hard disk drive servo system. Additionally, the designed loop shaping is evaluated by the Riccati procedure with regard to the system robustness. This paper applies the potential particle swarm optimization (PSO) to minimize the close loop gap between the loop shaping of the plant with weighting function and the plant with proposed controller. Moreover, the structure of proposed controller can be specified as the 2<sup>nd</sup> order controller which is uncomplicated to implement in the actual application. The simulation illustrates similar results in terms of the performance tracking and disturbance rejection of proposed controller against the H<inf>∞</inf> loop shaping. Furthermore, the system stability index called stability margin with 0.434 emphasizes the robustness of the proposed controller.