• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.346-350
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• 1996

In optical disk drives, one of commonly used pickup actuator is a Sliding and rotary type of pickup actuator which is cheaper than other pickup actuators and has simple assembly. However, it reported that non-linearity due to friction between a shaft and a sleeve had to be considerably analyzed in design and servo system in employing this type of pickup actuator. In this paper, this friction is modeled as a Coulomb's friction and the effect of friction is examined in the simulation. A digital servo system is applied to pickup actuator with friction in order to have good focusing servo. To enhance focusing servo performance using digital servo merit, frist PD-controller is applied to have fast response performance, second lead-lag compensator is applied to have stable focusing performance.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.5
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• pp.598-603
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• 2004

An optical head actuator of an optical disk drive consists of two servo mechanisms for the focusing and the tracking to acquire data from disk. As the rotational speed of the disk grows, the utilized lag-lead-lead compensator has known to be above its ability for precisely controlling the optical head actuator. To overcome the difficulty, this paper propose a new controller design method for optical head actuator based fuzzy proportional-integral-derivative (PID) control and the genetic algorithm(GA). It employs a two-stage control structure with a fuzzy PI and a fuzzy PD control and is optimized by the GA to yield the suboptimal fuzzy PID control performance. It is shown the feasibility of the proposed method through a numerical tracking actuator simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.67-73
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• 2007

An optical pick up generally has coupled dynamics between focusing and tracking servos. The coupled dynamics reduces tracking performance of optical disk drives. A conventional control method is holding the previous tracking control command in the presence of surface defect. The method has a long settling time. If the defective area is getting larger, objective lens will get away from the following track. In order to overcome this problem, this paper proposed a new control method for optical disk drives based on a prediction of tracking error and focusing error. We present how to compensate the coupled dynamics so that reduced setting time is achieved. It is verified by experiments that the proposed method brings an improved performance in the presence of surface defect as well as in the normal operating condition.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2221-2223
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• 2004

본 논문에서는 유전알고리즘을 기반으로 하여 설계된 광 디스크 드라이브의 광학헤드 구동기용 퍼지 PI/PD 제어기를 제안한다. 본 논문에서 제안하는 제어기는 광디스크 드라이브의 광학헤드용 구동기의 포커싱 서보계, 트랙킹 서보계를 제어할 수 있는 퍼지 제어기이며 유전알고리즘을 통해 최적의 퍼지 규칙을 도출한다. 그리고 이를 토대로 모의실험을 수행한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.559-564
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• 1994

Recently, a visual servoing for an eye-in-hand robot has become an interesting problem. A distance between a camera and a task object is very useful information for visual servoing. In the previous works for visual servoing, the distance can be obtained from the difference between a reference and a measured feature value of the object such as area on image plane. However, since this feature depends on the object, the reference feature value must be changed when other task object is taken. To overcome this difficulty, this paper presents a novel method for visual servoing. In the proposed method, a blur is used to obtain the distance. The blur, one of the most important features, depends on the focal length of camera. Since it is not affected by the change of object, the reference feature value is not changed although other task object is taken. In this paper, we show a relationship between the distance and the blur, and define the feature jacobian matrix based on camera defocusing to operate the robot. A series of experiments is performed to verify the proposed method.