• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.137-143
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• 2011

The pitch motion of a gravity-gradient satellite can be chaotic, depending on the ratio of mass moments of inertia and the eccentricity of the satellite orbit. For a precise prediction of motion, chaotic pitch motion has to be changed to non-chaotic motion. Feedback control can be used to obtain nonchaotic pitch motion. For chaos control and stabilization of the pitch motion of a gravity-gradient satellite, a feedback control system is designed, based on the linear nonautonomous system obtained by linearizing the nonlinear pitch motion. The control law obtained has two parameters and is applied to chaotic nonlinear pitch motion. The nonlinear control system satisfies the proposed control objectives in the range of the nonchaotic parameter space.

• Journal of Navigation and Port Research
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• v.33 no.5
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• pp.323-330
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• 2009

We have been developing an underwater robot for harbour construction using a parallel mechanism The robot is attached to the rope of a crane, which curries a large stone into the undersea The robot's yaw and pitch are controlled by hydraulic cylinders but its roll is uncontrollable. We mount propellers in both side of the robot to generate the roll motion This paper studies on the control for the roll motion of a underwater robot. A gyro-sensor is used to measure the angle in a roll motion We develop the dynamic model to describe the robot's roll motion by a second order non-linear system and identify the model parameters by recursive least square and adaptive identifier. PD control, recursive model based control and adaptive model based control are applied with the dynamic model which computes the control input to compensate disturbances. This paper introduces the underwater robot system and presents the simulated and experimental results of the proposed controller.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.7
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• pp.154-162
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• 1997

본 논문은 구속된 기계 시스템의 운동 제어 설계를 위한 새로운 방법을 제안한다. 구속된 기계 시스템의 운동 제어에는 지금까지 주로 사용되어온 Lagrange의 운동 방정식에 의한 모델링 보다 Udwadia와 Kalaba에 의해 제안된 운동 방정식에 의한 모델링이 더욱 적합함을 보였으며 이는 Holonomic 및 Nonholonomic 구속 조건을 비롯한 대부분의 구속 조건이 포함된다. 문헌에 잘 알려진 두 시스템을 시뮬레이션을 통하여 비교 함으로써 본 논문에 제안된 방법이 보다 우수한 결과를 보여줌을 확인 할 수 있었다. 또한 지금까지 불가능 하였던 비선형 일반 속도(gereralized velocity)를 포함한 구속 조건도 용이하게 제어됨을 보임으로써 광범위한 구속된 기계 시스템의 제어 문제를 통일된 방법으로 접근 할 수 있음을 제시하였다.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.5
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• pp.476-481
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• 1997

본 논문에서는 비구동 관절을 가지는 2링크 매니퓰레이터의 동력학 해석과 운동제어를 제1적분을 기초로 하여 전개하고 있다. 매니퓰레이터의 운동이 제1적분의 적분상수에 의해서 기술되는 것을 보이고, 제1적분을 이용하여 매니퓰레이터의 동력학을 해석하고 있다. 그리고 해석된 동력학을 적극적으로 이용하는 운동제어 알고리즘을 구성하고 시뮬레이션을 통하여 확인하고 있다. 끝으로 비구동 관절에 마찰이 작용하는 경우, 브레이크등의 보조수단을 이용하지 않고도 매니퓰레이터의 제어가 가능함을 보이고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1920-1927
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• 2000

본 논문은 cepstral 필터를 이용하여 지적인 비주얼 센싱을 위한 카메라의 운동 제어법을 제안한다. 화상은 pursuit 운동을 위하여 물체의 옵티컬 플로우가 필요하고, vergence 운동을 위하여 양안시차 정보를 필요로 한다. 그러나, 화상정보에는 올바른 정보와 잘못된 정보가 존재하기 때문에 해의 올바른 시차를 선택해야 하는데, 옵티컬 플로우의 계산에서와 마찬가지로 템플리트 매칭을 이용하여 올바른 정보를 선택한다. 그리고, 화상 중의 하나를 3 조각으로 분할한 후 각각 cepstral 필터링에 의하여 양안시차를 검출한다. 본 논문은 saccade 운동, pursuit 운동, vergence 운동에 관한 제어 알고리즘을 제안하고, 실험에 의하여 알고리즘을 비교 및 분석한다.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.674-682
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• 2003

Ship autonomous navigation is designated as what computerizes mental faculties possessed of navigation experts, which are building navigation plans, grasping the situation, forecasting the fluctuation, and coping with the situation. An autonomous navigation system, which consists of several subsystems such as navigation system, a collision avoidance system, several data fusion systems, and a motion control system, is based on an intelligent control architecture for the sake of integrating the systems. The motion control system, which is one of the most essential system in autonomous navigation system, controls its propulsion and steering gears to move the ship satisfying its hydrodynamic characteristics. This paper is the study on the ship movement control system and its implementation which are totally developed and run on virtual-world system. Receiving the high-level control values such as a waypoint presented from the collision avoidance system, the motion control system generates them to low-level control values for propulsion and steering devices. In the paper, we develop a ship motion controller using Oldenburger's theory based on mathematical fundamentals, and simulate it with various scenarios in order to verify its performance.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.547-549
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• 2000

버전스 눈동자 운동은 사람과 스테레오 시각을 가진 척추동물로 하여금 양안에 의해 응시점이 맞추어진 관심있는 물체까지의 떨어진 거리를 인식할 수 있도록 해준다. 이러한 버전스 눈동자 운동을 양안 헤드아이 로봇에 구현하기 위해서, 우리는 disparity flow와 flux를 이용하는 제어 모델을 개발하였다. 실험 및 결과 분석은 본 모델이 다양한 환경에서의 버전스 눈동자 운동을 효율적으로 제어할 수 있음을 보여준다. 인식-행동 주기가 실시간 프레임율에 근접하게 되면, disparity flow와 flux의 정확도는 증가되고 헤드아이 로봇의 버전스 눈운동을 더욱 정밀하게 제어하는 것이 가능해질 것이다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.285-290
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• 2004

Wave exciting force and moment generate the motions of a ship in waves. Since ship motion exerts the negative influences on a crew's operability, the safety of cargos, passenger's comfort, etc, the anti-rolling devices may be required to reduce such motion. In this paper, the dynamics of the anti-rolling devices such as passive and active moving weight stabilizer and anti-rolling tank, and fin stabilizer are mathematically modeled. While the effect of the motion of the anti-rolling device on a ship was taken into consideration in roll mode only in the past, the 6 DOF coupled equations of motion between a ship and the anti-rolling devices are constituted. Finally the motion of a ship with anti-rolling devices in waves is simulated through the developed simulation program.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.63-70
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• 2010

We are able to find many materials of pendulum dynamic/analysis using linearized model. Usually, analysis of pendulum is to calculate for velocity, period and angle by linearized model on Newton's law. In this paper, analyzed periodical movement of pendulum using nonlinear load model. That is, analyzed load value according to location of moving pendulum at real time. And for the shake of maneuver for pendulum's location, found load control value and compared result of linearized mode with nonlinear model. The result makes know that it is possibility of nonlinear load control model to apply to various model of movement object including flight object, pendulum and etc.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.2
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• pp.32-40
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• 1989

Dynamic ship positioning(DP) system is used to keep the position and heading of a ship, or a floating platform, above a pre-selected site on the seabed by using thrusters. This paper presents a control system based on filtering technique and optimal control theory. The planar motions of a vessel are assumed to consist of low frequency(LF) component and high frequency(HF) one. The former is mainly due to thrusters, current, wind and second order wave forces, while the latter is mainly due to first order oscillatory component of the wave force. Furthermore position measurement signals include the noise. By means of self-tuning filter and Kalman filter techniques, LF motion estimates and HF ones are seperately achieved from the position measurements of the vessel. The estimated LF motions are used as input to the feedback loops. The total thruster power is minimized using the Linear Quadratic Gaussian control theory. The performance of the vessel with the DP system is investigated by computer simulation.