• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.179-184
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• 2004

This paper is an overview of the experimental work using a Planar Magnetic Levitation Stage System structure proposed by Dr. Won-Jong Kim in his PhD thesis. Based on his results, we built an Experimental Test Stand (ETS), which enabled us to get accustomed with the new technology and to create new control structures and algorithms. The ETS is controlled by a powerful controller made of 4 DSPs mastered by a PC. This controller structure increases the controller bandwidth up to 10 kHz leading to a better emulation of an analog controller and leaving enough room for further development. Based on analyzing all the factors that can affect the performances of the system, we achieved a great accurate positioning performance of sub-nanometer RMS value.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.192-195
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• 2005

Nanometer operating linear motor is difficult to control the nano-positioning because of the vibration between structures changing of mechanical friction force happened by properties of the vibration and heat caused by operating of a mover. Therefore, it is required to analysis the vibration and heat about a mover. In this paper, we will analyze the property of vibration through analyzing by using FEM a mover of linear motor developed in the non-load situation and suggest the direction of optimal design about a mover by using method of DOE, also try to find the solution to operate the linear motor stabilized through the reducing weight of mover considering the vibration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1074-1078
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• 2005

In precision positioning applications, such as scanning tunneling microscopy and diamond turning machines [1], it is often required that actuators have nanometer resolution in displacement, high stiffness, and fast frequency response. These requirements are met by the use of piezoceramic actuators. A major limitation of piezoceramic actuators, however, is their lack of accuracy due to hysteresis nonlinearity and drift. The maximum error due to hysteresis can be as much as 10-15% of the path covered if the actuators are run in an open-loop fashion. Hence, the accurate control of piezoceramic actuators requires a control strategy that incorporates some form of compensation for the hysteresis. One approach is to develop an accurate model of the hysteresis and the use the inverse as a compensator. The Preisach model has frequently been employed as a nonlinear model for representing the hysteresis, because it encompasses the basic features of the hysteresis phenomena in a conceptually simple and mathematically elegant way. In this paper, a new numerical inversion scheme of the Preisach model is developed with an aim of compensating hysteresis in piezoceramic actuators. The inversion scheme is implemented using the first-order reversal functions and is presented in a recursive form. The inverted model is then incorporated in an open-loop control strategy that regulates the piezoceramic actuator and compensates for hysteretic effects. Experimental results demonstrate satisfactory regulation of the position of the piezoceramic actuator to the desired trajectories.