• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.71-72
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.378-391
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• 2002

A 250mm stroke aerostatic stage, which detects position with laser scale and is driven by linear motor, is made and analyzed positioning error in 20$\pm$ 0.5 $^{\circ}C$ controlled atmosphere, aiming at investigating positioning characteristic of ultra-precision stage. We prove this aerostatic stage has a 10nm micro step resolution by experiment. By means of analyzing laser interferometer system, the scale of measuring error is about 0.2-0.4$\mu\textrm{m}$ according to refractive index error from missing the temperature change. To improve laser interferometer system, compensate refractive index error using measuring data from thermocouple. And, confirm 0.10$\mu\textrm{m}$ repeatability and 0.13 $\mu\textrm{m}$ positioning accuracy using the compensating refractive index. Also, we confirm 0.07 ${\mu}{\textrm}{m}$ repeatability of the stage using capacitive displacement sensor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1394-1397
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• 2005

The object of this study was to design of micro stage, which is one of the equipments embodied in ultra precision positioning mechanism. Design factors for micro stage were decided a roundness of hinge, a thickness of hinge, a thickness of stage, a length of arms and a clearance of division. To obtain the $1^{st}$ natural frequency and equivalent stresses, FEM simulation was performed using the table of orthogonal arrays and Taguchi method was used to determine the optimal design parameters. As results of this study, the size of 1st natural frequency and equivalent stresses on micro stage was influenced significantly by a thickness of hinge and a length of arm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.311-314
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• 1997

According to the development of industrial equipment such as semiconductor manufacturing machines, optical device, and precision machine tool, a high-precision translation system with wide range has been required. This paper describes a high-precision 2-axis translation system, which consists of microstage and global stage. In order to achieve the highresolution in the long range, some engineering techniques are used. Three linear guides with flexible coupling are adopted to reduce the motor vibration in the global stage. A simple elastic hinge structure activated by five PZT is applied to reduce the angular dev~atlon. As the result of combination of microstage and global stage associated with some engineering techniques, the 2-axis translation system can measure the 200 X 200 mrn range with the nanometer accuracy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.539-542
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• 1997

We present a micro-positioning stage that has minimized geometrical error and can drive in the 4-axis. This stage divided into two parts: $Z\theta_x$ $\theta_y$, motion stage and$\theta_z$ motion stage. These stages are constructed in flexure hinges, piezoelectric actuators and displacement scnsors. The dynamic model for each stage is obtained and their FE (finite element) models are made. Using the Lagrange's equation, the motion of equation is found. Through the parametric analysis and FE analysis, sensitiv~ty of the design parameters is executed. Finally, fundamental frequencies, maximum stress, and displacement sensitivity for each stage are obtained. We expect that this micro-positioning stage be a useful micro-alignment device for various applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1207-1210
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• 2003

This paper deals with experiments for dynamic characteristics and performance evaluation of the 3-axis fine positioning stage developed in [1]. The features of the developed fine positioning stage are the long stroke due to the magnetically preloaded PZT actuators, the minimum motion crosstalk due to the use of a ball contact mechanism and the compact design. The dynamic characteristics of the actuator and the stage are tested with the preload changed in order to validate the actuator and the stage design. Performance evaluation is also made for the PZT actuators as well as the stage positioning accuracy. Experimental results show that the developed stage is accurate enough to be used for nanometer positioning.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.742-745
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• 2003

Piezoelectric elements driven ultra-precision stages have been used for high accuracy, fast response and high load rapacity. which are allowable to apply the stages to AFMs. Most of the piezoelectric driven stages are guided by flexure hinges for force transmission and mechanical amplification. However the flexure hinge mechanisms cause lack of position accuracy due to coupled and parasitic motions. Hence it is important that the mechanism design of the stage is focused on the stiffness of the flexure hinges to accomplish fast response and hish accuracy without the coupled and parasitic motions. In this study, some constraints for optimal design of a piezoelectric elements driven stage and a design method are proposed. Next, an optimal design is carried out using mathematical calculation. Finally the designed results are verified by FEM.

• 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.10
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• pp.60-65
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• 2002

For optimal design of micro stage, we measured the displacement of piezoelectric transducer that was based on voltage value. And the micro stage was analyzed using FEM with displacement data including voltage value of piezoelectric transducer. For verification of analysis results, the displacements were measured by using Laser-interferometer. And researchers confirmed to propriety on design of micro stage with FEM, we obtained 3.5% error rate between measurement results and analyzing results.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.111-119
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• 2006

The ultra-precision stage is demanded for some industrial fields such as semiconductor lithography, ultra-precision machining, and fabrication of nano structure. A new stage was developed for those applications in order to obtain nano meter resolution. This stage consists of symmetric double parallelogram mechanism using flexure hinges. The mechanical properties such as strength of the flexures and deformations along the applied force were analyzed using FEM. The stage is actuated by a piezoelectric actuator and its movement was measured by a ultra-precision linear encoder. In order to improve positioning performance, a PID controller was designed based on the identified second order transfer function. Experimental results showed that this stage could be positioned within below 5 nm resolution irrespective of hysteresis and creep by the controller.