• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.154-163
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• 1999

In this paper, an ultra precision positioning system has been developed using dual servo loop control. For positioning system having long distance with ultra precision , the combination of global stage and micro stage was required. A servo motor based ball screw is used as a global stage and the piezo actuator as a micro stage. For the improvement of positional precision, the digital Chebyshev filter is implemented in the developed to dual servo system. Therefore, the positional repeatability has been achieved within ${\pm}$ 10 mm, and this technique can be applied to develop precision semiconductor equipments such as lithography steppers and probers.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.249-252
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• 2002

For a precise position control with the resolution of a micrometer, a dual servo system is constructed using a linear motor and a piezoelectric actuator. The switching mode dual servo algorithm is implemented on a DSP board in which A/D and D/A converters are also mounted. It is shown by the experimental results that the precise position control is performed within a few micrometer of position error by using the dual servo system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.437-441
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• 1995

In this paper, the ultra precision positioning system for servo motor and piezo actuator using dual servo loop control has been developed. For positioning system having long distance with ultra precision, the combination of global stage and micro stage is required. Servo moter and ball screw are used as a master stage and piezo acuator as a fine stage. By using this system, an positional precision witin .+-. 30nm has been achieved at dual servo loop control. When using micro stage, an positional precision within .+-. 10nm has been achieved. This result can be applied to develop semiconductor equipment such as wafer stepper.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.206-215
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• 2013

In this paper, a synchronization control technique of dual-servo motor driven press system is proposed. An independent cascade PID control technique has been applied to the conventional press system for advancement of control stability. However, it is not easy to reduce synchronous error using the independent cascade PID control technique when some different load disturbances are involved in each motor. The eccentric error of the slide caused by the problem degrade the control performance of the BDC(Bottom Dead Center). In order to achieve reduction of the synchronous error between two servo motors and accurate position control simultaneously, a new control scheme comprised with cascade PID control loop and cross-coupling loop is proposed. In simulation using Matlab SIMULINK, the AC servo system is designed. The control performance of proposed technique is compared with conventional control technique to the model of AC servo system. Also, the sub-scale model of dual-servo motor driven press system which can replicate the slide motion is constructed for experimental verification for the performance of the proposed control technique. The cross-coupling control technique reveals more precise and stable performances in the position and synchronization controls.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.43-45
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• 2005

A High precision position control technique is used in many kind of industry areas. Especially this is to be one of the important parts in the development of precision machines. To get high precision and long range, dual servo voice coil motor(VCM) has been designed and implemented. In this paper, as a simulation and experimental result, the developed dual servo VCM shows the applicable possibility for precision machine system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.301-306
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• 2004

In this study, Dual servo mechanism with VCM(Voice Coil Motor) and PZT is designed for a high precision force and position control. We designed the VCM actuator and dual servo mechanism with leaf spring. VCM actuators, with their high linearity, simple structure, low weight, and high efficiency, are increasingly being used in micro-positioning applications. There are many kinds of VCM with a structure. VCM actuators are divided into two types by moving parts. One is moving magnet type and the other moving coil type. We described the properties of these two types of VCM. Design parameters of VCM are defined through the FEM simulation analysis of magnetic field and dynamic model of dual servo mechanism. These researches help to for decreasing loss in the air gap of VCM. We present dual servo mechanism is effective mechanism for a force control in hi h precision, properties of designed VCM.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.50-54
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• 2007

In this paper, a dual-servo type VCM (Voice Coil Motor) for the measuring of nano-level displacement and small thrust is proposed and developed. The shape of VCM for improving the resolution of displacement and ensuring a large displacement are presented. The FEM (finite element method) is utilized to analyze the characteristics of VCM that produces linear driving thrust and satisfies the thrust that the measurement system requires. The Prototype is fabricated and an experiment is performed in order to measure displacement. As a result of simulation and testing, the proposed VCM shows the applicable possibility for a nano-level measurement system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.823-824
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• 2013

• Journal of the Korean Society for Precision Engineering
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• v.23 no.2 s.179
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• pp.43-50
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• 2006

Recently, with rapid development of semiconductor and flat panel display, the manufacturing equipments are required to have large travel range, high productivity, and high accuracy. In this paper, an ultra precision decoupled dual servo (DDS) system is proposed to meet these requirements. And a control scheme for the DDS is studied. The proposed DDS consists of a $XY{\Theta}$ fine stage for handling work-pieces precisely and a XY coarse stage for large travel range. The fine stage consists of four voice coil motors (VCM) and air bearing guides. The coarse stage consists of linear motors and air bearing guides. The DDS is mechanically decoupled between coarse stage and fine stage. Therefore, both stages must be controlled independently and the performance of the DDS is mainly determined by the fine stage. For high performance tracking, the controller of fine stage consists of time delay control (TDC) and perturbation observer while the controller of coarse stage is TDC alone. With these individual controllers, two kinds of dual-servo control strategies are suggested: master-slave type and parallel type. By simulations and experiments, the performances of two dual-servo control strategies are compared.

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.31-36
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• 2007

Effect of coulomb friction and backlash on the single loop position control has been studied for the precision position control. We have showed the limit cycle on the single loop system which used a ball screw that had the backlash. Also, we have made an inner loop with a classical velocity and torque controller which was forcing the current of d axis to be zero by using a permanent-magnet synchronous motor and composed the outer loop with linear encoder for sensing a position of the loader. Also, we have used least squares fit(LSF) observer for reducing noise when we got velocity from position outputs. We have shown a good result by using the dual loop through simulation and experiment.