• 한국정밀공학회지
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• 제29권7호
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• pp.717-722
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• 2012

This paper presents the design and dynamic model of the finger exoskeleton actuated by Ionic Polymer Metal Composites (IPMC) to assist a tip pinch task. Although this exoskeleton will be developed to assist 3 degree-of-freedom motion of each finger, it has been currently made to perform the tip pinch task using 1 degree-of-freedom mechanism as the first step. The six layers of IPMC were stacked in parallel to increase the low actuation force of IPMC. In addition, the finger dummy was manufactured to evaluate the performance of the finger exoskeleton. The pinch task experiments, which were performed on the finger dummy with the developed exoskeleton, showed that the pinch force close to the desired level was obtained. Moreover, the dynamic model of the exoskeleton and finger dummy was developed in order to perform the various analyses for the improvement of the exoskeleton.

• 방송공학회논문지
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• 제24권2호
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• pp.273-280
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• 2019

360 비디오는 VR 응용의 확산과 함께 몰입형 미디어로 주목받고 있으며, MPEG-I Visual 그룹은 6 자유도(6DoF)까지의 몰입형 미디어를 제공하기 위한 표준화를 진행하고 있다. 제한된 공간내에서 전방위 6DoF를 제공하는 Omnidirectional 6DoF는 제공되는 제한된 수의 360 비디오로부터 임의의 위치에서의 뷰(view)를 제공하기 위한 가상시점 합성이 필요하다. 본 논문에서는 MPEG-I Visual 그룹에서 진행된 전방위 6DoF를 위한 합성에 대한 탐색실험의 성능 및 분석 결과를 기술한다. 즉, 합성하려는 가상시점과 합성을 위한 360 비디오의 입력시점 사이의 거리 및 입력시점의 개수 등의 다양한 실험조건에 따른 합성 성능 결과 및 분석을 제시한다.

• 한국컴퓨터정보학회논문지
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• 제11권4호
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• pp.35-45
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• 2006

본 논문에서는 휴대용 회전 유도탄 체계의 모델링과 성능분석에 사용할 수 있는 실시간 병렬처리 시뮬레이터 개발에 대하여 기술한다. 실시간 병렬처리 시뮬레이터는 항공기의 적외선 형상을 만드는 탐색기 에뮬레이터, 실시간 컴퓨터, 시스템 유닛. 유도 조종 장치 및 탐색기 프로세서 등과 같은 하드웨어 실물장치와 실시간 컴퓨터에 내장된 수학적 모델, 6 자유도 모델 및 공력 모델 등을 구현한 응용 소프트웨어 및 호스트 컴퓨터에 내장된 사용자 프로그램 등으로 구성되었다. 실시간 컴퓨터는 병렬로 연결된 여섯 개의 TI사 C-40 프로세서로 설계되었으며, 기계적 장치와 결합된 아날로그 전자회로를 이용하여 탐색기 에뮬레이터를 설계하였다. 시스템 유닛은 구성 요소간의 임피던스 정합 기능과 미세 신호를 처리하며, 시뮬레이터와 실물 유도탄 발사 장치의 연결이 가능하다. 개발된 실시간 병렬처리 시뮬레이터를 휴대용 회전 유도탄의 성능분석 장치로 사용하기 위하여 현장실험을 통한 결과 검증시험을 수행하였다.

• 한국항공우주학회지
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• 제33권3호
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• pp.57-64
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• 2005

2자유도 관성센서는 두 입력축이 기계적으로 연관되어 있기 때문에 해당하는 관성센서의 두 입력축에 동시에 고장이 발생할 확률이 매우 높다. 따라서 하드웨어 여분만으로 고장검출 및 분리를 수행하기 위해서는 최소한 4개의 관성센서를 사용하여야 한다. 2자유도 관성센서를 3개 중첩해서 사용하는 경우 기존의 하드웨어 여분기법으로는 고장검출은 가능하나 고장분리가 불가능하다. 본 논문에서는 이러한 문제점을 개선하기 위해서 비선형 필터인 Unscented Kalman Filter를 이용하여 얻은 정보를 해석적 여분으로 활용하여, 하드웨어 여분과 해석적 여분을 동시에 고려한 복합 고장검출기법을 제안하였다. 제안한 복합 고장검출기법의 성능을 검증하기 위해서 비선형 항공기 수치 시뮬레이션을 수행하였다.

• 제어로봇시스템학회논문지
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• 제15권5호
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• pp.543-547
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• 2009

This paper describes the design, simulation, development, and experiment of a six degree-of-freedom micropositioning parallel manipulator. A movable stage was supported with six links, each of which extends with a dc-servo micropositioning actuator. In case of parallel manipulator, while the solution of the inverse kinematics is easily found by the vectors of the links which are composed of the joint coordinates in base and platform, but forward kinematic is not easily solved because of the nonlinearity and complexity of the parallel manipulator's kinematic output equation with the multi-solutions. The movable range of the prototype was ${\pm}25mm$ in the x- and y-directions and ${\pm}12.5mm$ in the z-direction. The minimum incremental motion of the prototype was $1{\mu}m$ in the x- and y-directions and $0.5{\mu}m$ in the z-direction. The repeatability of the prototype was ${\pm}2{\mu}m$ in the x- and y-directions and ${\pm}1{\mu}m$ in the z-direction. The motion performance was also evaluated by not only the computer simulation of CAD model but also the experiment using a capacitive sensor system.

• Wind and Structures
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• 제23권3호
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• pp.253-273
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• 2016

Ice accretions on stay cables may result in the instable vibration of galloping, which would affect the safety of cable-stayed bridges. A large number of studies have investigated the galloping vibrations of transmission lines. However, the obtained aerodynamics in transmission lines cannot be directly applied to the stay cables on cable-stayed bridges. In this study, linear and nonlinear single degree-of-freedom models were introduced to obtain the critical galloping wind velocity of iced stay cables where the aerodynamic lift and drag coefficients were identified in the wind tunnel tests. Specifically, six ice shapes were discussed using section models with geometric scale 1:1. The results presented obvious sudden decrease regions of the aerodynamic lift coefficient for all six test models. Numerical analyses of iced stay cables associated to a medium-span cable-stayed bridge were carried out to evaluate the potential galloping instability. The obtained nonlinear critical wind velocity for a 243-meter-long stay cable is much lower than the design wind velocity. The calculated linear critical wind velocity is even lower. In addition, numerical analyses demonstrated that increasing structural damping could effectively mitigate the galloping vibrations of iced stay cables.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.688-696
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• 2017

This paper presents an integrated roll-pitch-yaw autopilot using an equivalent based sliding mode control for skid-to-turn nonlinear time-varying missile system with lumped disturbances in its six-equations of motion. The considered missile model are developed to integrate the model uncertainties, external disturbances, and parameters perturbation as lumped disturbances. Moreover, it considers the coupling effect between channels, the variation of missile velocity and parameters, and the aerodynamics nonlinearity. The presented approach is employed to achieve a good tracking performance with robustness in all missile channels simultaneously during the entire flight envelope without demand of accurate modeling or output derivative to avoid the noise existence in the real missile system. The proposed autopilot consisting of a two-loop structure, controls pitch and yaw accelerations, and stabilizes the roll angle simultaneously. The Closed loop stability is studied. Numerical simulation is provided to evaluate performance of the suggested autopilot and to compare it with an existing autopilot in the literature concerning the robustness against the lumped disturbances, and the aforesaid considerations. Finally, the proposed autopilot is integrated in a six degree of freedom flight simulation model to evaluate it with several target scenarios, and the results are shown.

• 한국항공우주학회지
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• 제39권12호
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• pp.1097-1106
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• 2011

제자리 비행하는 헬리콥터 전기체 형상으로부터 발사되는 유도무기 운동을 모사하기 위해 비정렬 중첩격자기법을 6자유도 운동 기법과 연계하여 비정상 해석을 수행하였다. 주로 터, 꼬리로터, 그리고 유도무기를 포함하는 동체로 구성되는 헬리콥터 전기체 형상에 대한 비정상 해석을 수행하였으며, 6자유도 운동 기법을 이용하여 헬리콥터에서 발사되는 유도 무기의 초기 발사 거동을 예측하였다. 발사위치 및 유도무기의 추력크기에 따른 발사거동을 비교하였으며, 주로터에서 발생하는 비정상 내리흐름에 따른 유도무기의 비행 특성을 분석하였다.

• 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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.286-291
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• 2002

We present the analysis and design of a new six degree-of-freedom parallel mechanism, Eclipse-II, which can be used as a basis for general motion simulators. This mechanism allows x, y and z-axis translations and a, b and c-axis rotations. Most significantly, it presents the advantage of enabling continuous 360 degrees spinning of the platform. We first describe the computational procedures for the forward and in inverse kinematics of the Eclipse-II. Next, the complete singularity analysis is presented for the two cases of end-effector and actuator singularities. Two additional actuators are added to the original mechanism to eliminate both types of singularities with in the workspace. Some practical aspects of the prototype development are introduced.