• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.465-468
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• 2001

An aerostatic stage has frictionless behavior, so it has a advantage of investigation into positioning characteristics. A one-dimensional aerostatic ceramic stage with ballscrew driven and laser scale feedback system is manufactured, aiming at investigating positioning characteristic of ultra-precision stage. We confirm, this ceramic aerostatic stage has a 10nm micro resolution, and can be reduced mean of position error by compensation of numeric control command. By means of analyzing relationship of position error and change of temperature, we build a on-line compensation algorithm of position error from the measured temperature data. So we can improve repeatability of ultra-precision stage up to 34%($0.095{\mu}$) of the normal condition.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.102.4-102
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• 2002

A deadzone compensator is designed for a positioning system using fuzzy logic. The classification property of fuzzy logic systems make them a natural candidate for the rejection of errors induced by the deadzone, which has regions in which it behaves differently. A tuning algorithm is given for the fuzzy logic parameters, so that the deadzone compensation scheme becomes adaptive, guaranteeing small tracking errors and bounded parameter estimates, formal nonlinear stability proofs are given to show that the tracking error is small. The fuzzy logic deadzone compensator is implemented on a positioning system to show its efficacy. 1. Deadzone Compansation 2. XY positioning table 3. Fuzzy Logic 4. Actuator nonlinearity

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.51-56
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• 2007

Precision positioning system with magnetostrictive actuator(MA) has widely used in manufacturing devices to control the positioning accuracy to meet the high load and stroke requirements. It has many advantage in comparison with piezoelectric actuator; high force, high strain, high efficient etc. But, the performance of Terfenol-D, the commercially available magnetostrictive material, is highly dependent on the prestress, magnetic field intensity and temperature. This paper present an experimental investigation of the temperature effect on displacement characteristics of magnetostrictive actuator. In this paper, compressed cold air is proposed to improve of positioning accuracy of magnetostrictive actuator. The compressed cold air cooling system has good cooling effect Experimental results confirming the effectiveness of the proposed cooling system as high precision positioning system are also has presented in this paper.

• Journal of Industrial Technology
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• v.19
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• pp.9-14
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• 1999

The voice coil actuator uses the Lorentz force between the magnetic field of the permanent magnets and the electromagnets to the motions and positioning. The small size, light weight and fast dynamic response of the these type actuators lead to admit them in the micro-positioning apparatus of the micro-machining systems. In this paper, the linear motion voice coil actuator is developed for the driving and positioning the rotating electrode of the electric discharge machine (EDM). The analyzed and measured results for the actuator are compared and discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1941-1948
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• 2003

This paper is about feasibility study of positioning device using magnetic suspension system which uses only vertical magnetic forces. The proposed system has inherited advantages from contact-free system, simple structure, and high expansibility in operating range different from conventional positioning devices. In this paper, the structure and operating principle are described and the linearized magnetic force and dynamic model are obtained. With the linear control theory, the experiments are executed. finally, the experimental results are shown.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.658-661
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• 1996

For ultraprecision positioning, the use of the twist roller-type friction drive is proposed. In our study, it is difficult to decrease the resolution of positioning below 100 nm when we use general servo motors. Therefore we propose the feed hive with a small lead like a the cam-roller type traction drive leadscrew and modify it more accurately. By using the semi-loop control system, the positioning resolution of the drive can be 22.4 nm, where the pulse per revolution of the motor is 655360 and the the lead is 0.734 mm.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.58-61
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• 2001

The purpose of this paper is a fuzzy logic controller for XY positioning system. The overall control system consists of three parts, the position controller, the speed controller, the fuzzy logic controller. Precise tracking is achieved by fuzzy logic controller. In practice, such systems contain many uncertainties. Therefore, the XY positioning system must receive and evaluate the motion of all axis for a better contouring accuracy. Cross coupled controller utilizes all axis position error information simultaneously to produce accurate contours. However, the existing Cross coupled controllers cannot overcome friction, backlash and parameter variation. So, we propose a fuzzy logic controller of XY positioning system. Experimental results show that the proposed fuzzy logic controller is effective to improve the contouring accuracy of XY positioning system.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.5 no.1
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• pp.46-52
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• 2002

A robust nonlinear observer, utilizing the sliding mode concept, is developed for the dynamic positioning of ships. The observer provides the estimates of linear velocities of the ship and bias from slowly varying environmental loads. It also filters out wave frequency motion to avoid wear of actuators and excessive fuel consumption. The main advantage of the proposed observer is in its robustness. Especially, the observer structure with a saturation function makes the proposed observer robust against neglected nonlinearties, disturbances and uncertainties. Since the mathematical model of DP ships is difficult to obtain and includes uncertainties and disturbances, it is very important for the observer to be robust. A nonlinear output feedback controller is derives based on the developed observer using the observer backstepping technique, and the global stability of the observer and control law is shown by Lyapunov stability theory.. A set of simulation was carried out to investigate the performance of the proposed observer for dynamic positioning of ships.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.15-22
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• 2014

With a conventional positioning apparatus, it is very difficult simultaneously to achieve desired driving ranges and precision levels at the sub-micrometer level. Generally, a lead screw and friction drive have been used as servo control systems. These have large driving ranges, and high-speed positioning is feasible. In this study, we present a global servo system controlled by a laser interferometer acting as a displacement measurement sensor for achieving positioning accuracy at the sub-micrometer level.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.3
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• pp.274-282
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• 2011

This paper is focused on dynamic modeling and control system design as well as vision based collision avoidance for multi-rotor unmanned aerial vehicles (UAVs). Multi-rotor UAVs are defined as rotary-winged UAVs with multiple rotors. These multi-rotor UAVs can be utilized in various military situations such as surveillance and reconnaissance. They can also be used for obtaining visual information from steep terrains or disaster sites. In this paper, a quad-rotor model is introduced as well as its control system, which is designed based on a proportional-integral-derivative controller and vision-based collision avoidance control system. Additionally, in order for a UAV to navigate safely in areas such as buildings and offices with a number of obstacles, there must be a collision avoidance algorithm installed in the UAV's hardware, which should include the detection of obstacles, avoidance maneuvering, etc. In this paper, the optical flow method, one of the vision-based collision avoidance techniques, is introduced, and multi-rotor UAV's collision avoidance simulations are described in various virtual environments in order to demonstrate its avoidance performance.