• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.337-343
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• 2012

NREL(National Renewable Energy Laboratory) Baseline controller conduct using method proposed RISO National Laboratory in Region 3. which designed the blade-pitch control system using a single degree-of-freedom model of the wind turbine. Idealized PID-Controlled rotor-speed error will respond as a second-order system with the natural frequency and damping ratio. RISO proposed specific natural frequency(=0.6 rad/s) and damping ratio(=0.7). If specific Eigen value apply to NREL 5 MW wind turbine, differ with pitch respond for simulation results of RISO report. Variation of specific eigen value investigate performance of NREL 5 MW wind turbine.

• 동력기계공학회지
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• 제6권1호
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• pp.96-101
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• 2002

In this paper, we address the problem of controlling an end-effector to track and grab a moving target using the visual servoing technique. A visual servo mechanism based on the image-based servoing principle, is proposed by using visual feedback to control an end-effector without calibrated robot and camera models. Firstly, we consider the control problem as a nonlinear least squares optimization and update the joint angles through the Taylor Series Expansion. And to track a moving target in real time, the Jacobian estimation scheme(Dynamic Broyden's Method) is used to estimate the combined robot and image Jacobian. Using this algorithm, we can drive the objective function value to a neighborhood of zero. To show the effectiveness of the proposed algorithm, simulation results for a six degree of freedom robot are presented.

• Journal of Advanced Marine Engineering and Technology
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• 제37권2호
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• pp.192-198
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• 2013

본 논문은 2축 구조를 가진 안정화 지향성 Pan-Tilt 시스템을 개발하기 위한 기초연구로서 2축 Pan-Tilt와 Pan-Tilt 구동 하드웨어 보드를 제작하고 표적 추적을 위한 제어기를 설계하는 내용이다. Pan-Tilt 시스템을 6 자유도 선박운동 시뮬레이터에 탑재하여 테스트 환경을 구축하고 RCGA를 이용하여 Pan-Tilt의 모델 매개변수를 추정한 다음, 추정된 모델과 RCGA에 기초하여 시뮬레이션과 실험을 수행함으로써 2 자유도 PID 제어기 동조의 유효성을 검토한다.

• Smart Structures and Systems
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• 제25권6호
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• pp.719-732
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• 2020

Real-time hybrid simulation (RTHS) which combines physical experiment with numerical simulation is an advanced method to investigate dynamic responses of structures subjected to earthquake excitation. The desired displacement computed from the numerical substructure is applied to the experimental substructure by a servo-hydraulic actuator in real time. However, the magnitude decay and phase delay resulted from the dynamics of the servo-hydraulic system affect the accuracy and stability of a RTHS. In this study, a robust stability analysis procedure for a general single-degree-of-freedom structure is proposed which considers the uncertainty of servo-hydraulic system dynamics. For discussion purposes, the experimental substructure is a portion of the entire structure in terms of a ratio of stiffness, mass, and damping, respectively. The dynamics of the servo-hydraulic system is represented by a multiplicative uncertainty model which is based on a nominal system and a weight function. The nominal system can be obtained by conducting system identification prior to the RTHS. A first-order weight function formulation is proposed which needs to cover the worst possible uncertainty envelope over the frequency range of interest. Then, the Nyquist plot of the perturbed system is adopted to determine the robust stability margin of the RTHS. In addition, three common delay compensation methods are applied to the RTHS loop to investigate the effect of delay compensation on the robust stability. Numerical simulation and experimental validation results indicate that the proposed procedure is able to obtain a robust stability margin in terms of mass, damping, and stiffness ratio which provides a simple and conservative approach to assess the stability of a RTHS before it is conducted.

• 대한조선학회논문집
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• 제36권1호
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• pp.1-14
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• 1999

Nakato & Ha[2]는 정상풍(steady wind) 및 파랑충격의 외력을 받는 소형경주정의 운동 및 전복에 관한 시뮬레이션 연구 결과를 발표하였다. 경주정의 시뮬레이션은 실험 데이터를 이용하고 외력을 고려한 항공역학에서 일반적으로 사용되는 6자유도 운동방정식을 풀어서 수행하였다. 본 논문에서는 선미플랩을 부착하여 양력을 발생토록하여 Nakato & Ha의 운동 방정식을 수정하였다. 플랩에 의한 경주정의 제어는 바람과 파도의 중첩된 외부교란에 의한 전복현상을 상당히 억제시킬 수 있음을 알았다.

• 한국전자파학회논문지
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• 제28권4호
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• pp.269-278
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• 2017

플랫폼과 이탈방사체가 동적인 상태에 있는 교전 시나리오에서 지상 추적 레이다에 대한 이탈방사체의 재밍/기만 효과를 분석한다. 플랫폼의 운동과 주변 간섭 유동장에 따른 이탈방사체의 궤적을 6자 유도 운동 방정식을 이용하여 해석한다. 실제적인 교전 시나리오에서 플랫폼과 이탈방사체의 운동 변화 및 이탈방사체의 RF 성능 변화에 따른 지상 추적 레이다에 대한 재밍 성능을 분석하며, 효과적인 지상 추적 레이다 기만을 위한 이탈방사체의 재밍 영역을 도출한다.

• 한국해양공학회지
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• 제27권6호
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• pp.56-64
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• 2013

Crabbing motion is the pure sway motion of a ship without surge velocity. Thus, it can be applied to a berthing operation. Crabbing motion is induced by a peculiar operation method called the push-pull mode. The push-pull mode is induced by using a combination of the main propeller and side thruster. Two propellers generating the same amounts of thrust and rotating in opposite directions produce some yawing moment on a vessel but do not induce longitudinal motion. With the additional operation of side thrusters, the push-pull mode is used to induce a large amount of lateral force. In this paper, three-degree-of-freedom equations of motion such as for the surge, sway, and yaw are constructed for the crabbing motion. Based on these equations of motion, a feedback linearization control method is applied to auto-berthing control for a twin-screw ship with side thrusters. The controller can deal with the nonlinearity of a system, which is present in the berthing maneuver of a twin screw ship. A simulation of the auto-berthing of a ship is performed to validate the performance of the designed controller.

• International Journal of Aeronautical and Space Sciences
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• 제6권2호
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• pp.1-16
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• 2005

Adaptive control methods are studied for the Satellite to isolate vibration in spite of the nonlinear system dynamics and parameter uncertainties of disturbance. First, a centralized control scheme is developed based on the particle swarm optimization(PSO) algorithm and feedback theory to automatically tune controller gains. A simulation study of a 3 degree-of-freedom device was conducted to evaluate the performance of the proposed control scheme. Next, since a centralized control scheme is hard to construct model dynamics and not goad at performance when controller and systems environment are easily changed, a decentralized control scheme is presented to avoid these defects of the centralized control scheme from the point of view of production and maintenance. It is based on the adaptive control methodologies to find PID controller parameters. Experiment studies were conducted to apply the adaptive control scheme and evaluate the performance of the proposed control scheme with those of the conventional control schemes.

• 조명전기설비학회논문지
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• 제28권6호
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• pp.30-39
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• 2014

Through a lot of papers, it has been concluded that fuzzy logic controller is superior to PI controller in motor speed control. Although fuzzy logic controller is superior to PI controller in motor speed control, the gain tuning of fuzzy logic controller is more complicated than that of PI controller. In this paper, using mathematical analysis of the PI and fuzzy controller, the design method of the fuzzy controller that has the same characteristics with the PI controller is proposed. After that, we can design the fuzzy controller that has superior performance than PI controller by changing the envelope of input of fuzzy controller to nonlinear, because the fuzzy controller has more degree of freedom to select the control gain than PI controller. The advantage of fuzzy logic controller is shown through mathematical analysis, and the simulation result using Matlab simulink has been proposed to show the effectiveness of these analysis.

• 한국가스학회지
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• 제18권1호
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• pp.68-74
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• 2014

본 연구에서는 헬멧의 충격응답을 분석하기 위한 단순진동모델을 제시하였다. 실제 헬멧 설계 및 검증과정에서 사용하는 데이터에 기반을 두고 단자유도 진동모델을 채택하였다. 충격에 의한 과도진동응답을 산출하여, 헬멧의 감쇠, 고유진동수, 충돌속도와 같은 인자들이 헬멧의 충격응답에 미치는 영향을 고찰하였다. 최대 G-가속도는 감쇠가 증가함에 따라 감소하였고, 감쇠비가 0.6 이상이 되면 최대 가속도의 값은 변화가 없었다. 고유진동수와 충돌속도에 관하여는 선형적으로 증가하였다. 두부 상해기준(Head Injury Criterion, HIC) 과 최대가속도의 관계도 제시하였다. 본 연구에서의 해석모델이 고품질 경량화 헬멧의 설계과정에서 경제성 제고에 활용될 수 있기를 기대한다.