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Author: search.filters.author.Kaitwanidvilai, SomyotSubject: 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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    Enhancing the performance of fixed-structure robust loop shaping control using genetic algorithm approach
    (2011-07-26)
    Olranthichachat, Piyapong
    ;
    Kaitwanidvilai, Somyot
    This paper is proposed an algorithm, Genetic Algorithm (GA) based fixed-structure H<inf>∞</inf> loop shaping control, to the problem-solving of conventional H<inf>∞</inf> loop shaping, such as high-order and difficult to be usable in general. In this approach, a structure of controller is specified combine H<inf>∞</inf> loop shaping method is solved by GA algorithm. Additionally, in the proposed technique, the desired performance weighting function, which is defined by using GA. The performance and robustness of the proposed controller are investigated in a pneumatic servo system in comparison with that of the controller designed by conventional H <inf>∞</inf> loop shaping. Results of simulation demonstrate the advantages of simple structure and robustness against plant perturbations and disturbances of the proposed controller. Experiments are performed to verify the effectiveness of the proposed technique.
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    Robust loop shaping control for designing high performance ACMC DC-DC converter
    (2010-12-01)
    Kaitwanidvilai, Somyot
    ;
    Olranthichachat, Piyapong
    DC-DC converter is an important circuit in Micro-grid system. To design a high performance and robust controller for this circuit, H infinity loop shaping gains increasing attention in the controller design. Being complex and high-order, robust controllers designed by H<inf>∞</inf> loop shaping are difficult to implement in practice. To overcome this problem, an algorithm, Particle Swarm Optimization (PSO) based fixed-structure H<inf>∞</inf> loop shaping control, has been proposed to design a robust controller. PSO algorithm is used to solve the H<inf>∞</inf> loop shaping design problem under a structure-specified controller. Additionally, in the proposed technique, the performance weighting function, which is normally difficult to obtain, is determined by the PSO. Simulations are performed to verify the effectiveness of the proposed technique.