• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.1
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• pp.41-48
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• 1994

The conventional resolved motion control is not applicable for the control of robots on the spacecraft on account of the floating base of the robots. When the robots perform the assembly or repair operations, the position and attitude of the base satellite are disturbed by the reaction force/moment caused by the robot motion. This reaction will cause error on the robot. motion. Therefore, we define a new type of Jacobian(Extended Jacobian) to minimize the effects of reaction on the accuracy of the robot performing assembly or repair operations. In this paper, we utilize the redundancy of the closed chain system to minimize the effects of the robot motion on the position and attitude of spacecraft. This will results in the accurate assembly and repair operations by the robot.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.4
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• pp.54-69
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• 1991

This study deals with the position control of a hydraulic cylinder system operated by two port 3-way high speed solenoid valve in Pulse-Width-Modulation mode, instead of using conventional electro-hydraulic servovalve. Due to the complexity and the relatively poor reliability of the servovalve, an actuator using simpler and more study high speed solenoid valve will be presented. The high speed solenoid valve acts as converters of electronic pulse signal to hydraulic ones. It has been pointed out that there are practical problems to be solved in the PWM system, that is (1) accuracy of positioning control becomes considerably insufficient because the system is affected by on/off action of the solenoid valves, and (2) serious nonlinerality appears in the valve characteristics as a result of the switching behavior of the valves. As a method to overcome these defects, the differential PWM driving method of a hydraulic cylinder that improved the steady-state-error, flow rate nonlinearity in simple PWM, and the hydraulic hunting of dead time compensated-PWM driving is proposed in this study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1529-1536
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• 2011

Recently, worldwide government policy is pursuing saving energy and preservation. add to this, the solar cells are getting the spotlight nonpolluting energy source, using a variety of products for solar cell. in this paper, we'll make solar tracking system for suitable of dynamic boat. we knew that general boats are using fixed solar cell, it's first time to use tracking system of solar cells for boats so it is hard to application. To solve this problem in this paper we use to a magnetic compass and GPS for suitable solar tracking system of dynamic movement and to analyze fixed and tracking solar system. frist. solar tracking device is designed two-axis control system. one-axis control system is taken a magnetic compass for making efficiency defence solar tracking sensor, two-axis control system apply GPS latitude and longitude data for SPA(Solar position algorithm) so we know the azimuth and altitude. it analyze data value of accuracy comparison from result. so the proposed algorithm confirm to have validity.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.179-181
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• 2004

This paper is proposed an adaptive fuzzy-neural network(A-FNN) controller based on the vector controlled induction motor drive system. The hybrid combination of fuzzy control and neural network will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed speed estimation of induction motor using A closed-loop state observer. The rotor position is calculated through the stator flux position and an estimated flux value of rotation reference frame. A closed-loop state observer is implemented to compute the speed feedback signal. The results of analysis prove that the proposed control system has strong robustness to rotor parameter variation, and has good steady-state accuracy and transitory response.

• Journal of Power Electronics
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• v.12 no.4
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• pp.604-614
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• 2012

This paper presents a comparative study of position sensorless control schemes based on back-electromotive force (back-EMF) estimation in permanent magnet synchronous motors (PMSM). The characteristics of the estimated back-EMF signals are analyzed using various mathematical models of a PMSM. The transfer functions of the estimators, based on the extended EMF model in the rotor reference frame, are derived to show their similarity. They are then used for the analysis of the effects of both the motor parameter variations and the voltage errors due to inverter nonlinearity on the accuracy of the back-EMF estimation. The differences between a phase-locked-loop (PLL) type estimator and a Luenberger observer type estimator, generally used for extracting rotor speed and position information from estimated back-EMF signals, are also examined. An experimental study with a 250-W interior-permanent-magnet machine has been performed to validate the analyses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.153-154
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• 2006

Development of sorting machine for photo diode and its control system is addressed. The sorting machine for optical communication device requires high positional precision because the alignment is one of the most important point in the sorting process. This sorting method describes how to detect the target chip's angle and position from the wafer. The machine vision system is used for the feedback control. This sorting machine is implemented by motion controller, machine vision and various solenoid valve and is interfaced with RS-232c, GPIB and PCI communication. This system gets the position accuracy within $1{\mu}m$ with our experiments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2501-2507
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• 1996

In this paper actively controlled air bearing is investigated to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled air beairng is composed of an air bearing, a gap sensor, a controller, and a piezo actuator. By controlling the position of air bearing with piezo actuator, the position of floating object is controlled. In this study the proportional-Integral-Derivative controller is employed. Active air bearing is investigated numerically and experimentally. There is good agreement between the simulation and the experimental results. It is shown that the stiffness and damping characteristics and positioning experimental results. It is shown that the stiffness and damping characteristics and positioning accuracy of air bearing can be improved by means of adopting actively controlled air bearing.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.768-783
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• 2020

Typically, a Dynamic Positioning System (DPS) uses a PID feed-back system, and it often adopts a wind feed-forward system because of its easier implementation than a feed-forward system based on current or wave. But, because a ship's drifting motion is caused by wind, current, and wave drift loads, all three environmental loads should be considered. In this study, a motion predictive control for the PID feedback system of the DPS is proposed, which considers the three environmental loads by utilizing predicted drifted ship positions in the future since it contains information about the three environmental loads from the moment to the future. The prediction accuracy for the future drifted ship position is ensured by adopting deep learning algorithms and a replay buffer. Finally, it is shown that the proposed motion predictive system results in better station-keeping performance than the wind feed-forward system.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.58-65
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• 1999

A magnetic levitation system requires a robustness to overcome a dynamic instability due to disturbances. In this paper a robust controller for a magnetically levitated fine manipulator is presented. The proposed controller consists of following two parts: a model reference controller and an $H_{\infty}$ controller. First, the model reference control stabilizes the motion of the manipulator. Then, the motion of the manipulator follows that of the reference model. Second, the $H_{\infty}$ control minimizes errors generated from the model reference control due to noise and disturbance since the $H_{\infty}$ control is a kind of robust control. The experiments of position control and tracking control are carried out by use of the proposed controller under the conditions of free disturbances and forced disturbances. Also, the experiments using PID controller are carried out under the same conditions. The results from above two controllers are compared to investigate the control performances. As the results, it is observed that the proposed controller has similar position accuracy but better tracking performances comparing to the PID controller as well as good disturbance rejection effect due to the robust characteristics of the controller. In conclusion. it is verified that the proposed controller has the simple control structure, the good tracking performances and good disturbance rejection effect due to the robust characteristics of the controller.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.2
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• pp.34-41
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• 1988

Nowadays the considerable improvements, not only in photogrammetric equipment but also in adjustment methods have led to a high accuracy of Aerial Triangulation and reach the step to obtain A.T. technique that uses Global Position System without ground control survery. The enterance of analytical plotter have made considerable development both in accuracy and in efficiency and improved working environment of A.T. by the combination of On-Line Analytical Plotting System. In this paper, in A.T., with using of analytical polotter, aims to improve the acccuracy in coordinates determination of low level control point. The result shows that in case of A.T. with analytical plotter AVIOLYT BC2, the accuracy of control points improves to 7% in planimetry and to 40% in height compared to A.T. with precision plotter Autograph A-8.