• Title/Summary/Keyword: Constrained Adaptive Feedforward Controller

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PERIODIC DISTURBANCE AND NOISE REJECTION METHOD USING HIRBERT TRANSFORM (힐버트 변환을 이용한 주기적인 외란 및 잡음제거)

  • Na, Hee-Seung;Park, Young-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.443-448
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    • 2000
  • In this paper, we propose a novel adaptive feedforward controller for periodic disturbance and noise cancellation, with a frequency tracking capability. It can be added to an existing feedback control system without altering the original closed-loop characteristics, which is based on adaptive algorithm. We introduce novel algorithm "Constrained AFC(adaptive feedforward controller) algorithm" that increase the convergence region regardless of the delay in the closed loop system. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the coefficients become time invariant. The proposed algorithm not only estimate the magnitude and phase of the tonal disturbance and noise but also track the frequency of the tone, which changes in quasi-static manner. The frequency tracking algorithm uses the instantaneous frequency approach based on Hilbert transform. A number of computer simulations have been carried out in order to demonstrate the effectiveness of proposed method under various conditions.

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Adaptive Feedforward Rejection of Microactuator Resonance in Hard Disk Drive Dual-stage Actuator Servo (하드디스크 드라이브 마이크로 구동기의 공진 영향 제거를 위한 적응 피드포워드 제어)

  • Oh, Dong-Ho;Lee, Seung-Hi;Baek, Sang-Eun;Na, Hee-Seung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1596-1600
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    • 2000
  • We propose a novel adaptive feed forward controller (AFC) design method for rejecting the effect of micro actuator resonance in the design of dual-stage actuator servo systems for disk drives. Microactuator's resonance is one of important issues in dual-stage actuator servo, which varies up to ${\pm}10%$ per product and even during operation. We derive an adaptive algorithm for the proposed AFC design, which turns out to be identical to the delayed-x LMS algorithm which is a special form of the filtered-x LMS algorithm. In the algorithm, coefficients of the AFC are adapted by the residuals of constrained structure defined in such a way that the coefficients become time invariant. Contrary to the conventional AFC, it considers the phase delay of closed-loop transfer function at resonance frequency for system stability. We also apply an adaptive algorithm with frequency tracking capability. The frequency tracking algorithm is induced by the orthogonality of AFC coefficients. Computer simulations are carried out to demonstrate effect of the proposed AFCs.

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Active Tonal Noise Control to Reduce the Low Frequency Tonal Sound (저주파 순음소음저감을 위한 능동 순음 소음제어)

  • 나희승;박영진
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1037-1042
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    • 1998
  • This paper discusses the dependence of the convergence rate on the acoustic error path in these popular algorithms and introduces new algorithms which increase the convergence region regardless of the time-delay in the acoustic error path. We also Propose a novel control algorithm (AFC/CAFC) for tonal noise cancellation. The proposed algorithm estimates the magnitude and phase of the tonal noise. The algorithm uses the steepest descent method for the phase/magnitude estimation. Performances of tile CAFC algorithm are presented in comparison with those by the AFC algorithm based on computer simulations and experiments.

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