• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.405-413
• /
• 2006

In general mechanical servo systems, friction deteriorates the performance of controllers by its nonlinear characteristics. Especially, friction phenomenon causes steady-state tracking errors and limit cycles in position and velocity control systems, even though gains of controllers are tuned well in linear system model. Even if sensor is used higher accuracy level, it is difficult to improve tracking performance of the position to the same level with a general control method such as PID type. Therefore, many friction models were proposed and compensation methods have been researched actively. In this paper, we consider that the variation of mover's mass is various by loading and unloading. The normal force variation occurs by it an other parameters. Therefore, the proposed control system is composed of main position controller and a friction compensator. A parameter estimator for a nonlinear friction model is designed by adaptive control law and adaptive backstepping control method.

• Journal of Navigation and Port Research
• /
• v.47 no.4
• /
• pp.256-270
• /
• 2023

In this study, a sliding mode (SM) controller for dynamic positioning (DP) was specifically designed for a turret connection operation of a ship or an offshore structure in which an arbitrary point on the structure could be controlled as the motion center instead of the center of mass. The SM controller allows control of the arbitrary point and provides capability to manage uncertainties in the dynamics of ships and offshore structures, external forces caused by unknown changing marine environments, and transient performance of DP systems. The Jacobian matrix included in kinematic equations of the controlled object was modified to design the SM controller to control based on an arbitrary point of ships or offshore structures. To ensure robustness of the controller, the Lyapunov stability theory was applied in the design of the SM controller. In general, for robustness in DP control, gain scheduling based on a proportional-derivative (PD) control algorithm is employed. However, finding appropriate gains for gain scheduling complicates the application of DP systems. Therefore, in this study, the SM control algorithm was considered to mitigate the complexity of the DP controller for ships and offshore structures. To validate the proposed SM control algorithm, time-domain simulations were conducted and utilized to evaluate the performance of the control algorithm. The effectiveness of the proposed SM controller was assessed by comparing simulation results with results of a conventional PD control algorithm applied in DP control.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.22 no.3
• /
• pp.267-272
• /
• 2012

This paper propose the implementation of robust fuzzy controller for controlling an active magnetic bearing (AMB) system with 6 degree of freedom (DOF). A basic model with 6 DOF rotor dynamics and electromagnetic force equations for conical magnetic bearings is proposed. The developed model has severe nonlinearity and uncertainty so that it is not easy to obtain the control objective. For solving this problem, we use the Takagi-Sugeno (T-S) fuzzy model which is suitable for designing fuzzy controller. The control object in the AMB system enables the rotor to rotate without any phsical contact by using magnetic force. In this paper, we analyze the nonlinearity of the active magnetic bearing system by using fuzzy control algorithm and desing the robust control algorithm for solving the parameter variation. Simulation results for AMB are demonstrated to visualize the feasibility of the proposed method.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2006.05a
• /
• pp.481-484
• /
• 2006

학교생활에서 학사업무의 생산성은 물론 구성원들의 편리하고 효율적인 학습활동 지원을 통하여 학습자의 교육 생산성을 높이기 위한 유비쿼터스 컴퓨팅 기술을 이용한 U-캠퍼스 구축이 요구된다. 따라서 본 논문에서는 U-캠퍼스 환경에서 여러 가지 상황 정보를 고려한 동적 접근 제어 메커니즘을 제안한다. 본 논문에서 제시한 동적 접근 제어 메커니즘은 기존의 역할 기반의 접근 제어(RBAC) 모델을 확장하여 사용자에게 부여된 역할 활성화 상태에 따라 접근 권한을 부여하는 방법으로, 상태검사 에이전트(agent)와 상황인식 에이전트, 상황인식 매트릭스(CAM)에 의한 위치와 시간 및 시스템 자원과 같은 여러 가지 동적인 상황 정보를 고려하여 효율적으로 권한을 부여 할 수 있다.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.544-547
• /
• 1997

In this paper, we propose a dynamic localization method using a rotating sonar and a map. The proposed method is implemented by using extended Kalman filter. The state equation is based on the encoder propagation model and the encoder error model, and the measurement equation is a map-based measurement equation using a rotating sonar sensor. By utilizing sonar beam characteristics, map-based measurements are updated while AMR is moving continuously. By modeling and estimating systematic errors of a differential encoder, the position is successfully estimated even the interval of the map-based measurement. Monte-Carlo simulation shows that the proposed global position estimator has the performance of a few millimeter order in position error and of a few tenth degrees in heading error and of compensating systematic errors of the differential encoder well.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.11a
• /
• pp.97-100
• /
• 2007

이 논문에서는 비전 시스템 기반 동작 인식 인터페이스 시스템으로 스테레오 카메라와 동적 제스처를 이용한 방식을 제안한다. 스테레오 카메라로부터 얻은 영상으로 손의 3차원 위치를 검출하고 이를 바탕으로 손의 동작을 추적하고 이를 인식함으로써 동적 제스처에 기반 한 동작 인식 방법을 제시한다. 이러한 깊이에 따른 제스처 동작을 인식하는 방법으로 단순한 컨트롤러부터 IPTV 제어나 가상의 마우스 제작이 가능한 본질적으로 편하고 자연스러운 인터페이스 구현 방향을 제시한다.

• Proceedings of the KOSOMBE Conference
• /
• v.1995 no.05
• /
• pp.78-81
• /
• 1995

본 연구에서는 슬라이딩 모드를 전기유압식 심실보조기의 직류모터제어기의 속도와 위치제어에 적용하였다. 슬라이딩 모드 컨트롤은 가변구조시스템(varaiable sturucture system)의 일종으로 적절한 내부스위칭 논리를 갖는 연속적인 부시스템(subsystem)의 모임으로 구성된다는 접에서 고정된 제어구조를 갖는 일반적인 제어시스템과 다르다. 이 시스템은 불연속적인 동적시스템이나 시변적인 요소를 갖는 시스템등에서 사용되고 있다. 이 논문에서는 슬라이딩 모드 제어를 적용하여 좌심실보조기를 제어하는 경우에 넓은 작동범위에서도 시스템이 안정적이며 혈류역학적인 외란에 대해서도 기준입력에 대한 속도의 추종이 잘 이루어지는지의 여부를 실제의 구현에 앞서 컴퓨터모델을 통해 검증하고 문제점들을 조사하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.295-298
• /
• 2008

In this paper, prototype dynamic modeling scheme to control ramjet propulsion systems were proposed. From the physical understandings of engine system, a typical 2nd-order system model was applied to simulate the dynamic characteristics of fuel supply system. The shock location varience in diffuser to chamber pressure fluctuation is calculated so that the out of phase between two signals was observed.

• Journal of the Society of Naval Architects of Korea
• /
• v.39 no.3
• /
• pp.57-63
• /
• 2002

This paper describes a control algorithm for the buffer of a deep-sea mining system, in which the buffer is connected to a long slender pipe and then to a surface ship on one end, and to a collector on sea floor through a flexible hose on the other end. A mathematical modeling is established for designing the controller for buffer thrusters, in which the dynamic response of the long pipe is taken into account based on the mode superposition method. The fluid loading acting on the pipe is estimated by using Morison's formula. For simplicity, the surface ship is assumed to be kept stationary, the reaction from the flexible hose is ignored and only the lateral motions are considered. In order to guide the buffer to react only to the low-frequency motion of the surface vessel, the FIR digital filter is introduced to a PID-based controller It can be shown numerically that the high frequency component of the ship's motion can be effectively filtered out by using the FIR low pass filter.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.7
• /
• pp.953-959
• /
• 2018

This paper deals with controlling surge oscillations of a mooring vessel system under large external disturbances such as wind, waves and currents. A control synthesis based on Sliding Mode Control (SMC) with a Super-Twisting Algorithm (STA) has been applied to suppress nonlinear surge oscillations of a two-point mooring system. Despite the advantages of robustness against parameter uncertainties and disturbances for SMC, chattering is the main drawback for implementing sliding mode controllers. First-order SMC shows convergence within the desired level of accuracy, in which chattering is the main obstacle related to the destructive phenomenon. Alternatively, STA completely eliminates chattering phenomenon with high accuracy even for large disturbances. SMC based on STA is an effective tool for the motion control of a nonlinear mooring system because it avoids the chattering problems of a first-order sliding mode controller. In addition, the error trajectories of controlled mooring systems implemented by means of STA form in the bounded region. Finally, the control gain effect of STA can be observed in sliding surface and position trajectory errors.