• Title/Summary/Keyword: Disturbance Signal

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Fast Compensator of Periodic Disturbance in Disk Drives (디스크 드라이브의 주기적 외란 고속 보상 제어)

  • 부찬혁;김호찬;강창익
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.2
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    • pp.153-163
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    • 2004
  • The control objective in hard disk drives is to move head as fast as possible to target track and position the head over the center of target track in the presence of external disturbances. The external shock or disk clamping error in manufacturing process causes the disk center to deviate from the disk rotation center. The disk shift acts on the control system as disturbance and degrades severely the performance of disk drives. In this paper, we present a new controller that compensates for the periodic disturbances very fast. The disturbance compensator is arranged in parallel with the state feedback controller. To avoid the interference with the state feedback controller, the compensator creates compensation signal without the feedback of system output until steady state. The pulse type controller is included additionally for improving the transient performance due to initial state. Finally, in order to demonstrate the superior performance of the proposed compensator. we present some experimental results using a commercially available disk drive.

Design of a Stable Adaptive Controllor in the Presence of Disturbance (외란 투입시 안정한 적응 제어기 설계)

  • 천희영;박귀태;박승엽
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.35 no.12
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    • pp.573-578
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    • 1986
  • The adaptive control of a plant in the presence of disturbance is considered. In sevral papers, it was shown that bounded disturbance made the basic adaptive scheme unstable. For achieving robust stability in adaptive control system in the presence of disturbance, the pureintegration in the adaptive law is limited by means of an additional feedback term. In this paper, the suggested adaptive control law has property that the output error converges to zero whether the disturbance exist or not, without the priori knowledge. The adaptive controller suggested assure the boundness of all signal in the overall system. Finally, computer simulation show the effectiveness of the suggested adaptive control law.

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Tracking Performance Improvement for Optical Disk Drive Using Error-based Modified Disturbance Observer (오차 기반의 수정된 외란 관측기를 이용한 광디스크 드라이브의 트랙 추종 성능 향상)

  • Kim Hong-Rok;Choi Young-Jin;Suh Il-Hong;Chung Wan-Kyun
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.7
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    • pp.637-643
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    • 2006
  • Generally, the tracking performance of optical disk drive(ODD) system can be improved using a disturbance observer(DOB). However, a DOB is not easily applied in an ODD system because an additional microprocessor, such as a digital signal processor(DSP), is needed. This paper shows how a DOB system can be replaced by the error-based modified disturbance observer(EM-DOB) when two mathematical conditions are satisfied. Due to the simplified structure of EM-DOB, the algorithm is easily implemented as an analog circuit, which is suitable for the ODD servo system. Additionally, in these algorithms, disturbances rejection performances can be tuned as Q filter parameters. Similar to a DOB system, three design guidelines of a Q filter can be applied. Experimental results of DOB and EM-DOB are evaluated under forced disturbances.

A Study on the PES Estimation for Developing High-TPI HDD (High TPI HDD 구현을 위한 PES Estimation에 관한 연구)

  • J. S. Koh;S. W. Kang;Y. S. Han;Kim, Y. H.;T. Y. Hwang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.319.1-319
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    • 2002
  • A frequency-domain PES estimation and its prediction method are proposed for the tightly-coupled servo/mechanical design of high-TPI HDD system above 100kTPI. The major two disturbance energies which are related with mechanical vibrations inside of HDD are used to predict the drive-level PES, while considering closed-loop servo dynamics. One is the torque disturbance which mainly comes from aerodynamic excitation of HSA system and the other is the displacement disturbance from disk-spindle dynamics. (omitted)

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Real-Time Detection of Seismic Ionospheric Disturbance Using Global Navigation Satellite System Signal (위성항법 신호를 이용한 지진에 의한 전리층 교란 실시간 검출 기법 연구)

  • Song, Junesol;Kang, Seon-Ho;Han, Deok-Hwa;Kim, Bu-Gyeom;Kee, Changdon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.8
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    • pp.549-557
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    • 2019
  • In this paper, we focus on the real-time detection method of a seismic ionospheric disturbance using Global Navigation Satellite System (GNSS) signal. First, the monitor for the detection of the seismic ionospheric disturbance is studied based on the estimated ionospheric delay using the GNSS signals. And then, the threshold for the automatic detection is computed. Moreover, to discriminate the seismic ionospheric disturbance against the other ionospheric anomalies due to other error sources such as cycle slips, the signatures of the ionospheric perturbation caused by the seismic wave is investigated. Based on the observation, the detection strategy is proposed. Using GPS observations collected from the 47 permanent stations in South Korea and Japan, the proposed real-time detection method is evaluated.

Position Control of Motion Stage using Disturbance Observer (외란관측기를 이용한 모션 스테이지의 위치제어)

  • Park, Hae-Chun;Choi, Myung-Soo;Byun, Jung-Hwan
    • Journal of Power System Engineering
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    • v.17 no.3
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    • pp.82-88
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    • 2013
  • For commercialized servo drives of the motion stage to include embedded controller, external terminal is provided for tracking command and encoder output, but internal terminal is not for control input. Thus, it is difficult to combine out signal of embedded controller with that of external compensator such as disturbance observer. In this study, for precise tracking control of motion stage without hardware change of the servo drive, tacking control system is composed of an inner loop of servo drive and an outer loop of disturbance observer. Then, the control system is designed so that the output response of actual plant corresponds with nominal model's in transient state as well as in steady state. Finally, the experiment results show that the designed control system is effective to reconcile actual plant behavior with nominal model under nonlinear friction and parameter perturbation.

AN ADVANCED DISTURBANCE REJECTION CONTROL FOR REPEATABLE RUNOUT IN DISK DRIVE SYSTEMS (컴퓨터 하드디스크의 반복 런아웃에서 비롯된 외란의 효율적 제어)

  • 용부중
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.1
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    • pp.60-67
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    • 2000
  • An improved disturbance rejection control scheme is presented for minimizing the position error due to the repeatable runout disturbances in high density disk drive systems The proposed control algorithm is capable of attenuating repeatable disturbances which is one of the major detractors to hard disk drive quality and performance. This is achieved by a sys-tematic combination of an optimal feedback component and a feedforward preview component. The feedback component is designed where the emphasis is placed on robustness. The feedforward component is on the basis of a preview control comprised of a measured disturbance signals which leads to better disturbance rejection capabilites. The designed con-troller is applied as a plug-in module to a high density hard disk drive with a pre-existing conventional servo controller. Simulations have been carried out to demonstrate the effectiveness of this control scheme in the reduction of the periodic disturbances.

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A Study on Control of Load Torque in the Induction Motor using a Disturbance Cancellation Observer (유도 전동기의 외란 상쇄 관측기를 이용한 부하토오크 제어에 관한 연구)

  • Hwang, L.H.;Jang, J.H.;Na, S.K.;Kim, Y.S.;Cho, M.T.;Song, H.B.
    • Proceedings of the KIEE Conference
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    • 2006.07b
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    • pp.1024-1026
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    • 2006
  • This paper designed a robust control of an induction motor using a disturbance cancellation observer of a feedforward control. The speed response of conventional PI controller characteristic is affected by variations of load torque disturbance. In the proposed system, the speed control characteristic using a feedforward control isn't affected by a load torque disturbance. High speed calculation and processing for vector control is carried out by ADMC300 digital signal processor. Validity of the proposed control method is verified through simulation and experimental result.

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A Novel Dead-Time Compensation Method using Disturbance Observer

  • Youn, Myung-Joong;Moon, Hyung-Tae;Kim, Hyun-Soo
    • Journal of Power Electronics
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    • v.2 no.1
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    • pp.55-66
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    • 2002
  • A new on-line dead-time compensation method for a permanent magnet (PM) synchronous motor drive is proposed. Using a simple disturbance observer without any additional circuit and off-line experimental measurement, disturbance voltages in the synchronous reference dq frame caused by the dead time and non-ideal switching characteristics of power devices are estimated in an on-line manner and fed to voltage references in order to compensate the dead-time effects. The proposed method is applied to a PM synchronous motor drive system and implemented by using software of a digital signal processor (DSP) TMS320C31. Simulations and experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed method.

Performance Analysis in Disturbance on Initial Alignment of Laser Inertial Navigation System Using Unscented Kalman Filter (UKF를 적용한 레이저 관성항법장치의 외란에 대한 초기정렬 성능분석)

  • Oh, Juhyun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.4
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    • pp.537-543
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    • 2014
  • RLG(Ring Laser Gyroscope) is a main device of LINS(Laser Inertial Navigation System). RLG has the lock-in region in which there is no output signal. To alleviate the lock-in problem, a mechanical oscillation, the dither motion, is applied on RLG. A LPF(Low Pass Filter) is usually used on the output of RLG and accelerometer to remove the noise that is made by the dither motion. When the LINS is induced the disturbance during the initial alignment, it takes more time on alignment due to the use of the LPF and a fixed gain controller. In this paper, an initial alignment using UKF(Unscented Kalman Filter) is designed and analysed. Analysis include comparison between conventional initial alignment loop using fixed gain type controller and proposed initial alignment using UKF. Moreover, Disturbance inducing test results are demonstrated.