• 제어로봇시스템학회논문지
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• 제13권9호
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• pp.856-860
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• 2007

This paper presents a robust tracking controller design method for the track-following system of an optical recording device. A tracking loop gain adjustment algorithm is introduced to accurately estimate the tracking vibration quantity in spite of the uncertainties of the tracking actuator. A minimum tracking open-loop gain is calculated by the estimated tracking vibration quantity and a tolerable limit of tracking error. A robust tracking controller is designed by considering a robust $H_\infty$ control problem with the weighting function of a slightly larger gain than the minimum tracking open-loop gain. The proposed controller design method is applied to the track-following system of an optical recording device and is evaluated through the experimental result.

• 제어로봇시스템학회논문지
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• 제9권4호
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• pp.277-283
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• 2003

Recently, near-field recording (NFR) disk drive schemes have been proposed with a view to increasing recording densities of hard disk drives. Compared with hard disk drives. NFR disk drives have narrower track pitches and are exposed to more severe periodic disturbances resulting from eccentric rotation of the disk. It is difficult to meet servo system design specifications for NFR disk drives with conventional VCM actuators in that the servo system for an NFR disk drive generally requires a feater gain and higher bandwidth. To tackle the problem various dual-stage actuator systems composed of a microactuator mounted on top of a conventional VCM actuator have been proposed. This article deals with the problem of designing a tracking servo system far an NFR disk drive adopting a dual-stage actuator. We summarize design constraints pertaining to the dual-stage servo system and present a new servo scheme using iterative teaming control. We design feedback compensators and an iterative teaming controller for a target plant and verify the validity of the proposed control scheme through a computer simulation.

• 한국지능시스템학회논문지
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• 제14권5호
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• pp.598-603
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• 2004

광디스크에 저장된 데이터를 읽기 위한 광디스크 드라이브는 광학헤드 구동기의 포커싱 서보계와 트랙킹 서보계로 구성된다. 기존에 사용하는 지상-진상-진상 보상기는 시스템의 배속이 증가하면서 광학헤드의 구동기 제어가 점점 어려워지는 추세이다. 따라서 본 논문에서는 광학헤드 구동기 서보계 구현을 위하여 유전알고리즘 기반 퍼지 PID 제어 광학헤드 구동기 설계 기법을 제안한다. 제안된 광학헤드 구동기는 두개의 퍼지 PI, PD 제어 블록으로 구성되며 두 제어기의 퍼지 규칙은 유전알고리즘을 사용하여 최적화된다. 구동기의 포커싱, 트랙킹 서보계의 플랜트 모델은 유사하므로 트랙킹 서보계의 모의 실험만을 통하여 제안된 기법의 우수성을 보인다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1455-1458
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• 1996

In this paper trajectory tracking control problems are described for a robot manipulator by using pneumatic actuator. Under the assumption that the so-called independent joint control is applied to the control system, the dynamic model for each link is identified as a linear second-order system with input time-delay by the step response. Then, an optimal servo controller is designed by taking account of such a time-delay. The effectiveness of the proposed control method is illustrated through some simulations and experiments for the robot manipulator.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.635-639
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• 1997

In order to design a system a process or plant must be put into a mathematical form for analysis and evaluation, and an appropriate controller must be designed to attain the desired system response. In this paper, the mathematical model for an optical pickup actuator is proposed and an H .inf. controller is employed to obtain the optimal focusing/tracking servo system behavior. Simulation and experiments are carried out to verify the performance of the proposed model.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.786-790
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• 2001

In this paper, we propose an optimum design method for optical pick-up actuators. Using this method, we can design an optimal pick-up actuator having the required tracking/focusing performances. Also, the designed actuator has the small mass, force constant for small size of magnetic circuit and large resistance for reduction of heat generation. Simulation results show that this method can be potentially implemented in all the pick-up actuators.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.509-516
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• 2012

This paper describes the testing and experimental characterization of a linear permanent magnet actuator, which is designed and developed for active vehicle suspension, under both static and dynamic conditions. Since the active suspension unit operates over a wide force-velocity range with varying duty ratios, it is essential to establish an effective thermal model which can be used for assessing temperature rise of the actuator under various operating conditions. The temperature rise of the actuator is measured and the results are compared with the prediction by the derived transient thermal model. It is shown that the measured actuator parameters and characteristics are closed to their predicted values. The linear actuator is controlled by a dSPACE system via a three phase inverter and its velocity tracking performance is presented.

• 한국정밀공학회지
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• 제16권11호
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• pp.9-15
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• 1999

A piezoelectric actuator is widely used in precision positioning applications due to its excellent positioning resolution. However, the piezoelectric actuator lacks in repeatability because of its inherently high hysteresis characteristic between voltage and displacement. In this paper, a controller is proposed to compensate the hysteresis nonlinearity. The controller is composed of a PID and a neural network part in parallel manner. The output of the PID controller is used to teach the neural network controller by the unsupervised learning method. In addition, the PID controller stabilizes the piezoelectric actuator in the beginning of the learning process, when the neural network controller is not learned. However, after the learning process the piezoelectric actuator is mainly controlled by the neural netwok controller. In this paper, the excellent tracking performance of the proposed controller was verified by experiments and was compared with the classical PID controller.

• 한국소음진동공학회논문집
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• 제14권12호
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• pp.1207-1222
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• 2004

In this paper, the explicit equations on the power consumption and sensitivity ratio of VCM-type actuator for disk drive are proposed. The power consumption and sensitivity ratio is derived in frequency domain. The power consumption during the track following of the actuator can be described well in frequency domain and it can be used to calculate the total power dissipation of the actuator which is needed to compensate the tracking and focusing errors. Also, the sensitivity ratio of an actuator is derived by using the reference servo of a disk drive and will be used to optimally obtain the performances of the actuator. This sensitivity ratio can persuasively explain the basis of the target performances of the actuator in the considerations of the reference servo. The usefulness of the proposed equations for the sensitivity ratio and power consumption of an actuator is shown by a lot of simulations. In the near future, we will verify the simulation results by experiments.