• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.911-920
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• 2016

For the pitch and yaw axis attitude control of launch vehicle, thrust vector control which changes the direction of thrust during the engine combustion is commonly used. Hydraulic actuation system has been used generally as a drive system for the thrust vector control of launch vehicles with the advantage of power-to-weight ratio. Nowadays, due to the developments of highly efficient electric motor and motor control techniques, it has done a lot of research to adopt electro-mechanical actuator for thrust vector control of small-sized launch vehicles. This paper describes system design and test results of the prototype of direct drive electro-mechanical actuation system which is being developed for the thrust vector control of $3^{rd}$ stage engine of KSVL-II.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.2
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• pp.1-11
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• 2001

In this paper, a chattering alleviation VSS controller for the sinusoidal type BLDC motor is designed. Dead Zone function is proposed to change the chattering occurring in the transient state from high frequency to low frequency and time varying gains arc applied for the control input to eliminate the steady state excessive chattering in the conventional ISM. The proposed Dead Zone function represents the sliding layer composed of two switching surfaces and if a state vector exists in this layer, the chattering don't occur. Simulation and experimental results confirm the useful effects of the above algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.823-829
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• 2006

In this paper presents approaches to the design of a hybrid fuzzy logic proportional plus conventional integral- derivative(fuzzy P+ID) controller in an incremental form. This controller is constructed by using an incremental fuzzy logic controller in place of the proportional term in a conventional PID controller. The PID type controller has been widely used in industrial application due to its simply control structure, easy of design, and inexpensive cost. However, control performance of the PID type controller suffers greatly from high uncertainty and nonlinearity of the system, large disturbances and so on. This paper presents a hybrid fuzzy logic proportional plus conventional integral derivative controller In comparison with a conventional PID controller, only one additional parameter has to be adjusted to tune the Fuzzy P+ID controller. In this case, the stability of a system remains unchanged after the PID controller is replaced by the Fuzzy P+ID controller without modifying the original controller parameters. Finally, the proposed hybrid Fuzzy P+ID controller is applied to BLDC motor drive. Simulation results demonstrated that the control performance of the proposed controller is better than that of the conventional controller.

• International Journal of Control, Automation, and Systems
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• v.2 no.1
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• pp.83-91
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• 2004

The purpose of this paper is to obtain an accurate nonlinear system model to test various control schemes for a motion control system that requires high speed, robustness and accuracy. An industrial sewing machine equipped with a Brushless DC motor is considered. It is modeled by a neural network that is configured as an output-error dynamical system. The identified model is essentially a one step ahead prediction structure in which past inputs and outputs are used to calculate the current output. Using the model, a 2 degree-of-freedom PID controller to compensate the effects of disturbance without degrading tracking performance has been de-signed. In this experiment, it is not preferable for safety reasons to tune the controller online on the actual machinery. Experimental results confirm that the model is a good approximation of sewing machine dynamics and that the proposed control methodology is effective.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.973-974
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• 2011

이 논문은 단상 외전형 브러시리스 모터의 권선 인덕턴스를 해석적인 방법으로 산정하고 실험결과와 비교하였다. 모터의 초기 설계단계에서 사용하는 자기회로해석은 매우 유용하고, 인덕턴스는 자기회로해석에서 중요한 파라미터이다. 회전자계의 영향은 쇄교 자속으로 표현할 수 있고 자속 쇄교수는 인덕턴스에 비례하기 때문이다. 따라서 모터의 특성해석을 위해서 인덕턴스 산정은 매우 중요하다. 해석적인 방법으로 권선 인덕턴스를 산정하였고 회전자의 영향을 무시하였다. 그리고 LCR 미터와 전류 변화법으로 각각 권선 인덕턴스를 측정하였다. 해석값과 전류 변화법으로 측정한 권선 인덕턴스는 비슷하였다. 이 논문에서 제시한 권선 인덕턴스의 해석적인 산정방법은 모터의 초기 설계단계에서 자기회로해석으로 특성을 해석하는 데 도움이 될 것이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.466-469
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• 1995

This paper presents a design and performance of the 6 D.O.F linear motion table with a magnetic bearing suspension. The linear positioning of the table with a 150mm stroke is driven by a brushless DC Linear motor and the other attitudes of the stage are controlled by the analog PD controller with magnetic bearing actuators. Each magnetic bearing unit which consists of 3 electromagnets, 3 capacitance probes and 3 backup bearings affords controlled forces by detecting the air gap between the probes and guideways. An integral type capacitance probe amplifier is equipped on the upper plate of the table so that the probe line to the probe amplifier can be shorter therefore the problems due to the stray capacitance and noise can be reduced. Form the pitch-yaw errormeasured by the autocollimator, the vertical and horizont straightness errors of the table are derived that they are maintained below 1.mu. m over 100mm stroke. The positioning accuracy of the linear motion is maintained below 2 .mu. m and the repeatability error is below 1 .mu. m

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.3
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• pp.181-187
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• 1996

A frictionless positioning device using cone-shaped active magnetic bearings(AMBs) is developed, which is driven by a brushless DC motor equipped with resolver. The cone-shaped AMB feature that the structure is simple and yet the five d.o.f. rotor motion is controlled by four magnet pairs. A linearized dynamic model, which accounts for the relationship between input voltage and output current in the cone-shaped magnet, is developed and the azimuth motion of the frictionless positioning device is modeled as the second order system. The feedback controller is designed by using linear quadratic regulator with integral action optimal control law so that the cone-shaped AMB system is stabilized and the frictionless positioning device gets the zero steady state. It is observed that the linearized dynamic model is adequate and the frictionless positioning device can achieve the tracking accuracy within the sensor resolution.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.119-123
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• 2002

실제의 브러시리스 직류 전동기의 역기전력 파형은 고가의 정밀 서보 전동기를 제외했을 때, 이상적인 사다리꼴이나 정현파의 형태가 아닌 그 형태에 근접한 모양을 갖는다. 하지만 브러시리스 직류 전동기의 운전은 역기전력 파형을 이상적이라고 가정하여 사다리꼴인 경우는 3상 2여자 직류 제어를 하고, 정현파인 경우에는 3상 3여자 교류 제어를 하는 것이 일반적이다. 일반적인 3상 3여자 운전은 3상 2여자 운전에 비해 공간 자계의 높은 분해능을 제공하고, 3상 2여자 운전에서 구조적으로 나타날 수밖에 없는 정류 시의 토크 리플도 발생하지 않는 장점을 갖는다. 따라서 본 논문에서는 위의 두 측면을 고려하여, 즉 이상적인 형태의 역기전력 형태를 갖지 않는 실제 전동기의 특성과 3상 3여자 운전의 특성을 적용하여, 역기전력의 형태에 상관없이 적용할 수 있는 3상 3여자 직류 제어 방법을 제안하고 이에 대한 센서리스 운전을 제안한다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.3
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• pp.11-17
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• 2017

The aerial support air sculptures currently exhibited in indoor spaces are similar to simple ad balloons, using multiple rope strands. Users now want more advanced unfixed sculptures, and hope these will develop into buoyant sculptures that can maintain the attitudes that users want on their own. This study investigated an attitude control system for unfixed levitation sculptures that can levitate with no rope and continuously maintain a certain attitude at a height specified by the user. To facilitate levitation, the exterior part of the sculpture was made of lightweight fibers, and the interior part was filled with helium gas. The controller was composed of a microprocessor of the dsPIC30F line from microchip, gyro, acceleration, and earth magnetic field sensors, and a highly efficient brushless DC (BLDC) electric motor. The attitude and position control system requires scheduling considering the trajectories of the sculpture and the control system, because the roles of the overall components are more important than those of a single controller. Furthermore, the system was designed like a fusion system that is expanded and controlled as a total controller, because it is interconnected with various sensors. The attitude control system of buoyant sculptures was implemented in this study, such that it can actively cope with the position, direction, stopping, and time aspects. The system performance was then evaluated.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.8
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• pp.353-362
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• 2006

This paper illustrates the practical design procedure on a position control of an electrical fin actuator for the guided missile using Time Delay Control(TDC) and Enhanced Time Delay Observer(ETDO). Since TDC is robust to the model uncertainties such as the parameter variation and the external disturbance, it has been frequently used in nonlinear control systems. For a position control of an electrical fin actuator in the missile system, TDC requires the velocity sensor as well as the position sensor. To resolve the problems of the cost, the space and the malfunction due to the velocity sensor, ETDO is used as the velocity observer. ETDO is enhanced version of TDO that has the problems of the reconstruction errors and the restriction on selecting its gains. To maximize the control performance, the parameters of ETDO are optimized by using the genetic algorithm. The effectiveness of this approach is proved through a series of simulation studies and experiments, and the designed controller is compared with the typical TDC and TDC using the reduced oder observer.