• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1218-1220
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• 1992

This paper presents the three section sliding mode control algorithm based on variable structure current controller design in a synchronous frame and indirect field oriented control method, and applies it to the position control of induction motor. This control scheme solves the problem of robustness loss during the reaching phase that occurs in a conventional VSC strategy, and ensures the stable sliding mode and robustness enhancement throughout an entire response. As the performance of a VSI fed induction motor drives depends on the characteristics of inner loop current controller, it is desired that the current controller have the fast tracking and robust nature. Therefore, we introduced the voltage mapping table based on the concept of voltage space vector for variable structure current control, and implemented fully digital control system using 16-bit microcontroller with on-chip peripherals without additional processing circuits. Simulation and experimental results confirm the validity of this control scheme for robust AC servo drive system of VSI fed induction motor.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권8호
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• pp.361-366
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• 2001

This thesis proposes a fuzzy logic cross coupled controller for a multi axis servo system. The overall control system consists of three elements: the axial position controller, the speed controller, and a fuzzy logic cross coupled controller. In conventional multi axis servo system, the motion of each axis is controlled independently without regard to the motion of other axes, in which the contour error, defined as the shortest distance between the desired and actual contours is compensated only by the position error of each axis. This decoupled control approach may result in degraded contouring performance due to such factors as mismatch of axial dynamics and axial loop gains. In practice, such systems contain many uncertainties, Therefore, the multi axis servo system must receive and evaluate the motion of all axes 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. Also, since it is difficult to obtain an accurate mathematical model of multi axis system, here we investigate a fuzzy logic cross coupled controller method. Some simulations and experimental results are presented to illustrate the performance of the proposed controller.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.88-97
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• 2013

This paper presents a robust air-to-fuel ratio (AFR) control algorithm for managing exhaust gas recirculation (EGR) systems. In order to handle production tolerance, deterioration and parameter-varying characteristics of the EGR system, quantitative feedback theory (QFT) is applied for designing the robust AFR control algorithm. A plant model of EGR system is approximated by the first order transfer function plus time-delay (FOPTD) model. EGR valve position and AFR of exhaust gas are used as input/output variables of the plant model. Through engine experiments, parameter uncertainty of the plant model is identified in a fixed engine operating point. Requirement specifications of robust stability and reference tracking performance are defined and these are fulfilled by the following steps: during loop shaping process, a PID controller is designed by using a nominal loop transmission function represented on Nichols chart. Then, the frequency response of closed-loop transfer function is used for designing a prefilter. It is validated that the proposed QFT-based AFR control algorithm successfully satisfy the requirements through experiments of various engine operating points.

• 한국항해항만학회지
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• 제31권5호
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• pp.325-332
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• 2007

본 연구에서는 조이스틱을 이용하여 프로펠러와 타, 선수/선미 쓰러스터를 갖는 선박의 접이안을 위한 제어 알고리즘을 개발하였다. 조이스틱으로부터 전진 방향 및 회전 방향의 속도명령을 받아 전진 방향 및 회전 방향의 속도를 제어하는 MIMO(Multi-Input Multi-Output) 비선형 제어 알고리즘을 개발하기 위해 저속 조종수학모형을 사용하였다. 또한, 본 연구에서는 비선형 및 PID 제어기의 성능을 검증하기 위해 선박 접이안 가상 HILS(Hardware in the Loop Simulation) 프로그램을 구현하였다. HILS 프로그램은 LabWindow/CVI를 이용하여 개발하였으며, 사용자는 선박의 현재 위치와 원하는 궤적을 모니터를 통해 본 후 조이스틱을 이용하여 선박의 전진 방향 및 회전방향 속도를 제어함으로서 선박을 조종한다. 시뮬레이션 결과를 보면 비선형 제어기와 PID 제어기는 개루프 조이스틱 제어기보다 타와 쓰러스터의 입력 크기뿐 아니라 선박의 위치오차 면에서도 우수한 성능을 보였다.

• 한국항행학회논문지
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• 제10권2호
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• pp.113-120
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• 2006

본 논문에서는 로봇 매니퓰레이터가 기준 궤적을 추종할 수 있도록 영상기반 강인제어기를 제안하였다. 카메라로부터 획득된 목표물의 특징점을 원하는 특징점 좌표로 로봇이 이동할 수 있도록 기준 궤적을 생성하고, 제어 입력에 포함되는 로봇 동역학부의 파라미터 불확실성을 보상하기 위한 강인제어기를 설계하였다. 또한 자코비안에 불확실성이 존재하는 경우 이를 보상하기 위한 제어 입력을 갖는 영상기반 강인제어기를 제안하였다. 시스템의 안정도는 Lyapunov 안정도 판별법을 이용하여 검증하였다. 5-링크 2 자유도의 로봇 매니퓰레이터를 대상으로 제안된 제어기를 적용한 모의실험과 실험을 통하여 제어 성능을 입증하였다.

• 한국전자통신학회논문지
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• 제11권12호
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• pp.1209-1218
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• 2016

4대의 전동실린더를 이용하여 대형 유리판과 같은 부하를 신속하고 안전하게 이송하기 위해서는 동기오차가 허용된 범위 내에서 지속적으로 유지되어야 한다. 본 연구에서는 4대 이상의 전동실린더 간의 동기화에 적용 가능한 동기제어기법이 제안된다. 이 동기제어시스템은 디커플링 구조에 기반을 두고 있으며, 기준모델, 위치제어기 그리고 동기제어기로 구성된다. 기준모델은 각각의 실린더에 대해 상호 분리된 동기오차와 제어입력의 계산이 가능하도록 한다. I-PD형의 위치제어기는 각 실린더가 오버슈트와 입력포화를 일으키지 않고 지령을 추종하도록, 그리고 진상보상기형의 동기제어기는 루프정형을 통해 안정적으로 정밀한 동기가 되도록 설계 된다. 끝으로 토크외란이 인가된 상태에서도 4개의 실린더가 신속하고 안정적으로 동기를 유지하면서 목표지점에 도달됨을 시뮬레이션으로 검증한다.

• 대한기계학회논문집A
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• 제32권3호
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• pp.232-239
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• 2008

The position sensors used in a magnetic bearing system are desirable to provide some degree of fault-tolerance as the rotor position is necessary for the feedback control to overcome the open-loop instability. In this paper, we propose an inductive position sensor that can cope with a partial fault in the sensor. The sensor has multiple poles which can be combined to sense the in-plane motion of the rotor. When a high-frequency voltage signal drives each pole of the sensor, the resulting current in the sensor coil contains information regarding the rotor position. The signal processing circuit of the sensor extracts this position information. In this paper, we used the magnetic circuit model of the sensor that shows the analytical relationship between the sensor output and the rotor motion. The multi-polar structure of the sensor makes it possible to introduce redundancy which can be exploited for fault-tolerant operation. The proposed sensor is applied to a magnetically levitated turbo-molecular vacuum pump. Experimental results validate the fault-tolerance algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1440-1443
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• 1997

The optimal residual generator based on parity relation approach for the fault detection and isolation of a arge diesel engine actuator position servo system is presented. The closed-loop residual generator is designed to have robustness against modeling errors and noise. Main purpose of the fault detection and isolation system in the process is to detect and isolate two important faults, i.e., actuatro fault and fault of speed sensor, that, if not detected and compensated, degrade the overall control system performance. Simulation results are give to show the practical applicability of the fault detecrtion and isloation scherme.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.890-895
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• 1990

A theoretical and experimental study of a single link flexible arm a tip mass is presented for the translational end-point positioning. The problem of shifting the end-point from its initial position to the commanded position by the amount of W $_{d}$ is considered for the open loop control such that the base follows up the given path function. The theoretical results are obtained by applying the method of the Laplace transform to the governing equation, and the solution is calculated by the method of numerical inversion. Experimental results are obtained and compared with the theoretical ones.s.

• 대한기계학회논문집A
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• 제33권5호
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• pp.482-488
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• 2009

Dancer system is typically used equipment for attenuation of tension disturbances. In industrial converting machines, a composite type of dancer system is applied which is mixture of active and passive dancer. It includes feedback position control loop of roll with pendulum dancer and its characteristics is different from passive and active one. In this paper, a mathematical model of the pendulum dancer was derived including PI position feedback controller and it was analyzed by using a pole-zero map and bode plot under various conditions. It was found out that velocity, length of span and inertia were associated with the performance of regulation. It was suggested that the length of upstream span should be greater than that of the downstream and the inertia should be smaller for improvement of the performance. The results can be used for design guidelines of the industrial dancer system.