• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2631-2633
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• 2004

This paper describes the construction of a half sphere screen driving tilting simulator that can perform six degree-of-freedom( DOF) motions simmulator to a tilting train. The mathematical equations of Tilting Train dynamics are first derived from the 6-DOF bicycle model and incorporated with the bogie. carbody, and suspension subsystems. The equations of motion are then programmed by visual C++ code. To achieve the simulator functions. a motion platform that is constructed by six electric-driven actuators is designed. and its kinetics/inverse kinetics analysis is also conducted. Driver operation signals such as carbady angle, accelerator. and tilting positions are measured to trigger the Tilting dynamics calculation and further actuate the cylinders by the motion platform control program. In addition. a digital PID controller is added to achieve the stable and accurate displacements of the motion platform. The experiments prove that the designed simulator is adequate in performing some special rail mad driving situations discussed in this paper.

• 한국해양공학회지
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• 제20권6호
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• pp.114-122
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• 2006

The most important thing in the container terminal is to handle the cargo effectively in a limited time. To achieve this objective, many strategies have been introduced and applied. If we consider the automated container terminal, it is necessary that the cargo handling equipment is equipped with more intelligent control systems. From the middle of the 1990s, an automated rail-mounted gantry crane (RMGC) and rubber-tired gantry crane (RTG) have been developed and widely used to handle containers in the yards. Recently, in these cranes, equipment like CCD cameras and sensors have been mounted to cope with the automated terminal environment. In this paper, we try to support the development of more intelligent automated cranes that make the cargo handling be performed effectively in the yards. For this plant, we ought to consider modeling, tracking control, anti-sway system design, skew motion suppressionand complicated motion control and suppressing problems. In this paper, the system modeling and a tracking control approach are discussed, based on a two-degree-of-freedom (2DOF) servo-system design. From the simulation results, the good control performance of the designed control system is evaluated.

• 수산해양교육연구
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• 제29권1호
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• pp.286-296
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• 2017

This paper conducted a simulation to research the motion of a vessel, which had the flooding accident in the Bering Sea in 2014, thereby being flooded and un-steerable. As the wind condition was very harsh, the vessel was modeled as 3D including large upper deck structures and the Fujiwara's method was used for an estimation of the effect of wind forces and moments acting on ship. In the case of wave influence, AQWA-Drift that enables considering the effects of drift force and AQWA-Naut that enables considering the effects of green water were mainly used. Basically, loading and flooding condition were equal to the accident condition but half-drained condition was also used to consider drain ability. Furthermore, both 6 DOF and 5 DOF option that Yaw motion is fixed, were utilized to compare the steerable and un-steerable condition. As a result, the author found out that what roll angle triggers green water, how often it happens, and how the vessel moves on the stormy weather condition.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.612-620
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• 2006

This paper proposes an optimal trajectory generation method for biped robots for walking up-and-down stairs using a Real-Coded Genetic Algorithm (RCGA). The RCGA is most effective in minimizing the total consumption energy of a multi-dof biped robot. Each joint angle trajectory is defined as a 4-th order polynomial of which the coefficients are chromosomes or design variables to approximate the walking gait. Constraints are divided into equalities and inequalities. First, equality constraints consist of initial conditions and repeatability conditions with respect to each joint angle and angular velocity at the start and end of a stride period. Next, inequality constraints include collision prevention conditions of a swing leg, singular prevention conditions, and stability conditions. The effectiveness of the proposed optimal trajectory is shown in computer simulations with a 6-dof biped robot model that consists of seven links in the sagittal plane. The optimal trajectory is more efficient than that generated by the Modified Gravity-Compensated Inverted Pendulum Mode (MGCIPM). And various trajectories generated by the proposed GA method are analyzed from the viewpoint of the consumption energy: walking on even ground, ascending stairs, and descending stairs.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.164-169
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• 2001

The active magnetic bearing has many advantages - an active positioning, no contact and lubrication free motion - and is widely used in high precision motion stages. But, the conventional magnetic bearings composed of electromagnets only are power consuming due to their bias current and have the excessive heat generation, which can make the repeatability of the positioning system worse. To overcome this drawback, we developed a novel permanent magnet (PM) biased linear magnetic bearing for a high precision magnetically levitated stage. The permanent magnets provide a bias flux and generate a bias force, and the electromagnet increases or reduces a flux of the permanent magnets and gives a levitation force. This paper presents a theoretical magnetic circuit analysis, FEM analysis and experimental data from the 1-DOF tests, and compares the theoretical power consumption of the electromagnetic bearings and the PM biased linear magnetic bearings. The PM biased linear magnetic bearing presented in this paper gives better load capacity but lower power consumption than a conventional electromagnetic bearing and will be adopted in our 6-DOF high precision linear positioning maglev stage.

• 로봇학회논문지
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• 제18권1호
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• pp.37-47
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• 2023

This paper introduced how to construct Denavit-Hartenberg (DH) parameters from the Unified Robot Description Format (URDF). URDF is convenient for describing a robot even though the robot is very complex. On the other hand, DH convention is not an easy notation for many novices who want to describe a robot. Therefore, most vendors provide URDF and users prefer to use URDF to describe a robot. However, some controllers or algorithms are based on DH parameters to perform kinematics, dynamics, control, etc. To connect URDF and DH parameters, we present a three-step approach to construct DH parameters from URDF. The first step is to define the joint axis for constructing DH parameters. The second step is constructing DH parameters to define joint character. The final step is constructing DH parameters to define the coordinate frame of the child link. This approach is based on intuitive vector calculation and guarantees the uniqueness of DH parameters. To verify our approach, we applied our approach to a simple one-link robot, a manipulator with 6 DOF, and a quadruped robot with 3 DOF per leg. We verified that our approach worked well based on forward kinematic results.

• 한국항공우주학회지
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• 제38권3호
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• pp.288-293
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• 2010

본 논문은 장 단거리 공대공 미사일의 치사율을 계산하고, 대상 미사일의 모델을 구성하여 모의 발사 시험 프로그램을 개발하고자 한다. 신뢰성 있는 치사율을 계산하기 위해서는 신관과 탄두에 대한 많은 자료와 실험이 필요하지만 현실적으로 그런 작업을 수행 하기엔 한계가 있다. 따라서 본 논문에서는 참고문헌[3-6]에서 획득한 치사율에 대한 자료를 분석하여 치사율을 계산하였다. 모의시험을 위한 시뮬레이션 프로그램은 MATLAB/SIMULINK를 이용하여 6 DOF 시뮬레이션 모델을 구성하였으며, 수직, 수평 가속도 피드백을 이용한 자동비행 알고리즘과 PNG(Proportional Navigation Guidance)을 이용한 유도명령 알고리즘, 그리고 시간지연과 오차를 고려한 탐색기(seeker)의 동적 모델을 구성하여 적용하였다. 최종적으로 정면발사, 측면발사, 후면발사의 3가지 경우에 대하여 모의 비행을 수행하여 결과를 정리하였으며, 이때 목표물은 일정한 방향을 가지고 등속비행을 하는 것으로 설계하였다.

• 대한조선학회논문집
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• 제53권4호
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• pp.315-328
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• 2016

Techniques for determinating hydrodynamic derivatives of underwater tow-fish using CFD(Computational Fluid Dynamics) are described in this paper. Main components of hydrodynamic derivatives are added mass, linear damping and non-linear damping coefficients. In this study, linear and non-linear damping coefficients for translational velocities are settled by CFD analysis. In order to analyze the underwater tow-fish, UlsanFOAM based on open-source CFD code, namely OpenFOAM, is employed. By simulating pitch and yaw angle variation of underwater tow-fish, 6DOF(Degree-of-Freedom) forces and moments are estimated at each attitudes. In order to determinate the hydrodynamic derivatives, curves(forces and moments vs attitude) for CFD results are fitted by least square methods. To demonstrate the applicability of the current approach, two different problems(impulsive side towing and straight towing) are simulated and all results are validated.

• 방송공학회논문지
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• 제25권5호
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• pp.672-684
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• 2020

시차 기반 영상처리에 대한 연구들이 증가함에 따라 저해상도 및 모션 블러된 라이트필드 영상을 복원하는 연구는 필수적이 되었다. 이러한 기법들은 라이트필드 영상 향상 과정으로 알려져 있으나 두 개 이상의 문제를 동시에 해결하는 기존의 연구는 거의 존재하지 않는다. 본 논문에서는 라이트필드 공간 영역 초해상도 복원과 모션 블러 제거를 동시 수행하는 프레임워크를 제안한다. 특히, 저해상도 및 6-DOF 모션 블러된 라이트필드 데이터셋으로 훈련하는 간단한 네트워크를 생성한다. 또한 성능을 향상하기 위해 생성적 적대 신경망의 지역 영역 최적화 기법을 제안하였다. 제안한 프레임워크는 정량적, 정성적 측정을 통해 평가하고 기존의 state-of-the-art 기법들과 비교하여 우수한 성능을 나타냄을 보인다.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.21-28
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• 2010

본 논문에서는 만타형상 무인잠수정(Manta-type unmanned underwater test vehicle)의 운동성능과 제어기설계에 대한 성능을 해석하기 위한 수학모델을 정립하여 시뮬레이션 프로그램을 개발하였다. 6자유도 운동방정식을 이용하여 Matlab/Simulink로 시뮬레이션 프로그램을 구성하였다. 개발된 시뮬레이션 프로그램을 이용하여 만타형상 무인잠수정의 동역학적 운동성능을 해석하였으며, 무인잠수정의 제어성능을 해석하기 위하여 PID(비례-미분-적분)제어기와 슬라이딩모드(Sliding mode)제어기를 설계하여 만타형상 무인잠수정의 제어성능을 해석하였다. 설계된 제어기는 무인잠수정의 수심제어(Depth control)와 방향제어(Heading control)에 사용되었다. 설계된 제어기의 성능을 확인하기 위하여 미해군 대학원의 AUV II와 비교하였다. 설계된 수심제어기와 방향제어기를 이용하여 만타형 무인잠수정의 설계목표에 부합하는 항해제어 시뮬레이션을 실시하였다.