• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.174-181
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• 2001

Nowadays, the improvement and development of Multi-media and information & communication technology is rapidly processed. They need large data storage capacity. So that, many studies and researches in data storage have been carried out. According to them, the data storage capacity has been increased. But the limitation of storage capacity is happened for several problems. One of them is spot & pit size in optical and magnetic data storage and another is the resolution of actuators. The problems in spot & pit size are covered by new data storage methods-- for examples, AFM(Atomic Force Microscopy), MO(Magneto-optical) system, and NFR(Near-Field decoding) system etc. But the resolution limit of an actuator was not developed and doesn\`t follow up the development of spot & pit size. Because of them, we should improve a resolution of an actuator. Especially, in this paper an actuator if studied and designed for NFR (in using SIL(Solid Immersion Lens) system. It is a dual stage actuator, which consists of a Fine actuator and a Coarse actuator. and should desire 100nm accuracy. Its actuating force generation method is VCM(Voice Coil Motor). The Fine actuator is composed of 4-leaf springs and a bobbin wrapped by coil. The Coarse actuator has Coils and 3-Roller bearings. Also, The Characteristics of designed actuator for NFR system is estimated by Sine-Swept mode and LDV(Laser Doppler Vibro-meter).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1453-1459
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• 2012

The dual stage manipulator is composed of the voice coil motor (VCM) and piezoelectric ceramics transducer (PZT), which can produce the high precise displacement and express a well dynamic performance. However, inaccurate modeling of the dual stage will exacerbate the positioning accuracy. This paper presents an approach to model the dual stage system by using bond graph theory. And the state space equations can be derived through the bond graph straightforwardly, which can be used in computing simulations. Through designing the compensators for the dual stage system and simulating, the dual stage performs better dynamics characteristic than the single actuator system.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1309-1314
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• 2003

The high precision positioning mechanism is used in various industrial fields. It is used in semiconductor manufacturing line, test instrument, Bioengineering, and MEMS and so on. This paper presents a positioning mechanism with dual servo system. Dual servo system consists of a coarse stage and a fine motion stage. The course stage is driven by VCM and the actuator of fine stage is the PZT. The purposes of dual servo system are stability, higher bandwidth, and robustness. Lead compensator is applied to this control system, and is designed by PQ method. Designed compensator can improve property of positioning mechanism.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.86-94
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• 2007

In this paper, a dual stage servo mechanism has been developed for image tracking system to improve control performances such as small rise time, small overshoot, small settling time, small stabilization error etc. A secondary stage, a platform, actuated by a pair of electro-magnets is mounted on a conventional elevation gimbal. In this mechanism, the gimbal provides large range but slow motion and the platform provides small range but fast positioning. A sliding mode control is applied to the platform positioning to attain robust performances and stability in the presence of the disturbance related to dynamic coupling of the gimbal and the platform. Results from experiments illustrate that the suggested dual stage mechanism controlled by the sliding mode control is effective in improving responses and attenuating the disturbance response related with dynamic coupling.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.163-170
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• 2002

The quality of a precision product, in general, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the work piece in the process. Recently the positioning accuracy level has reached to the level of submicron and long range of motion is required. For example, for 1 GDARM lithography, 20nm accuracy and 300mm stroke needs. This paper refers to the lithography stage especially to fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM (Linear DC Motor) is used and for fine one VCM is used. In this study, we propose the new structure of VCM for the fine actuator. It is 3 axis precision positioning stage for an aligner system. After we perform the optimal design of the stage to obtain the maximum force, which is related to the acceleration of the stage to accomplish throughput of product. And we controlled this fine stage with TDC. So we obtained 50nm resolution. So later more works will be done to obtain better accuracy.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.2
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• pp.153-160
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• 1999

Dual-stage servo system for super-high density HDD has the chances of being composed of the coarse actuator(VCM) for track-seeking control and the fine actuator(microactuator) for-following control in near future. This paper presents the concept design of dual-stage servo system and the track-following control using an electrostatic microactuator for super-high density HDD. The electrostatic microactuator is designed and fabricated by MEMS(micro-electro-mechanical system) process. Both the nonlinear plant(voltage/displacement-to-electrostatic force) and the linear plant(electrostatic force-to-displacement) of the microactuator are established. Inverse function of the nonlinear plant is employed for a feedforward nonlinear compensator design. And feedforward control effect of this compensator is shown by time-domain experiments. A track-following feedback controller is designed using the feedback nonlinear compensator which is derived from the feedforward nonlinear compensator. The track-following control experiment is done to show the control efficiency of the proposed control system. And, excellent track-following control performance(2.21kHz servo-bandwidth, 7.51dB gain margin, $50.98^{\circ}$phase margin) is achieved by the proposed control system.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.708-717
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• 2003

With the development of precision manufacturing technologies, the importance of precision positioning devices is increasing. Conventional actuators, dual stage or mechanically contacting type, have limitation in coping with performance demands. As a possible solution, magnetic suspension technology was studied. Such a contact-free system has advantages in terms of high accuracy, low production cost and easy adaptability to high precision manufacturing processes. This paper deals with magnetically suspended multi-degrees of freedom actuator which can realize large linear motion. In this paper, the operating principle is explained with the magnetic force analysis, and the equations of motion are derived. Experimental results of the implemented system are also given.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.463-463
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• 2000

A dual-stage positioner for fast and fine robotic manipulations is presented. By adopting the merits of both coarse and fine actuator, a desirable system having the capacity of large workspace with high resolution of motion is enabled. We have constructed an ultra precision XY positioner with dual-stage mechanism where the PZT driven fine stage is mounted on the motor driven XY positioner and applied it to fine tracking controls and micro-tele operations as a slave manipulator. We describe essential merits of the compound actuation mechanism and some control strategies to successfully utilize it with proper servo system design. Through experimental results, the effectiveness of the coarse/fine manipulation by the dual-stage positioner will be shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.46-51
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• 2001

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. In this system, a voice coil motor (VCM) is used as the primary stage while a milliactuator is used as the secondary stage. We have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce controller design method, PQ method. PQ method reduces the controller design problem for DISO(dual-input/single-output) systems to two standard controller design problems for SISO(single-input/single-output) problems. The first part of PQ method directly address the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.45-46
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• 2006

In this paper, a dual stage servo mechanism has been developed for image tracking system to improve transient control performances such as small rise time, small overshoot, small settling time, etc. A secondary stage, a platform, actuated by a pair of electro-magnets is mounted on a conventional elevation gimbal. In this mechanism, the gimbal provides large range but slow motion and the platform provides small range but fast positioning. A sliding mode control is applied to the platform positioning to attain robust performances and stability in the presence of the disturbance related to dynamic coupling of the gimbal and the platform. Results from experiments illustrate that the suggested dual stage mechanism controlled by the sliding mode control is effective in improving transient responses and attenuating the disturbance related with dynamic coupling.