• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.365-377
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• 2017

In this paper, we propose a method to identify the parameters of a rotorcraft slung load system using the modal characteristics of a flexible cable. The proposed method estimates the length of the cable and the mass of the payload by means of a frequency analysis. Dynamic equations of the slung load system with the flexible cable are derived using Udwadia-Kalaba equation (UKE) in order to build a simulation program, and the similarity of the simulated slung load movement is verified by comparison with flight test results. Using the computer simulation program, we show that the proposed method works well within various parameter ranges.

• 제어로봇시스템학회논문지
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• 제6권11호
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• pp.955-962
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• 2000

Although large space structures(LSS) such as a space station, a solar power station satellite, etc., are theoretically distributed parameter and infinite-dimensional systems, they have to be modeled into a lumped parameter and large finite-dimensional system for control system design. Besides, there remains the fundamental problem that the modeled large finite-dimensional system must be controled with a much smaller dimensional controller due to the limitation of computing resources. This causes the spillover phenomenon which degrades control performances and reduces the stability margin. Furthermore, it may destabilize the entire feedback control system. In this paper, we propose a novel spillover suppression method in the active vibration control of large flexible structures by using eigenstructure assignment. Its validity and effectiveness are investigated and verified by the numerical experiments using a simply supported flexible beam, which is modeled to have four controlled modes and eight uncontrolled modes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.369-373
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• 1992

Force control of a planar two-link structurally flexible robotic manipulator is considered in this study. The dynamic model is obtained by using the extended Hamilton's principle and the Galerkin criterion. A method is pressented toobtain the linearized equations of motion in Cartesian space for use in designing the control system. The approachto solving the control problem is to use feedforward and feedback control torques. The feedforward torques maneuver the flexible manipulatro along a nominal trajectory and the feedback torques minimize any deviations from the nominal trajectory. The linear quadratic Gaussian/loop transfer recovery (LQG/LTR) design methodology is explotied to design a robust feedback control system that can handle modeling errors and sensor noise, and operates on Cartesian space trajectory errors. The Lqg/LTR compenstaor together with a feedforward ollp is used to control the flexible manipulator. Simulated results are presented for a numerical example.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.693-698
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• 2001

The analysis of actuating forces (or torques) and joint reaction forces (or moments) are essential to determine the capacity of actuators, to control the system and to design the components. This paper presents an inverse dynamic analysis algorithm for flexible multibody systems with closed-loops in the relative joint coordinate space. The joint reaction forces are analyzed in Cartesian coordinate space using the inverse velocity transformation technique. The joint coordinates and the deformation modal coordinates are used as the generalized coordinates of a flexible multibody system. The algorithm is verified through the analysis of a slider-crank mechanism.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1631-1636
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• 2003

The purpose of this study is to analyze the phenomena of the thermally-induced vibration for the flexible space structure due to abrupt change of radiation heating circumstance using the numerical analyze and experiment test. In order to verify this structure, numerical approaches on the simplified flexible tube were compared with experimental test results at the ground experimental facility In this analyze, it was found that the thermal deformation occurs firstly due to fast radiation heating of flexible structure and then the thermally-induced vibration would be induced due to small periodic change of temperature. According to comparison of numerical and experimental result, in case of no tip mass, the first mode vibration by the numerical analyze was O.78Hz same as that of the experimental result However in case of increase tip-masses of 8g l6g, 50g and 100g, the first modes vibration theoretical analyze were 1.75Hz, 1.3Hz, 0.87Hz and O.73Hz, in decrease trend respectively and those by experimental test were 234Hz, 1.5Hz, O.78Hz and O.78Hz in decrease trend respectively Although using the simpled equation for the estimation, the estimation results were similar to experimental results.

• 대한기계학회논문집A
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• 제26권4호
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• pp.602-608
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• 2002

The flexible structure like solar array and antenna in spacecraft shows very sensitive responses to the inner or outer disturbance and noise. And the spacecraft becomes more complex and larger as it has various mission and role. But since the spacecraft need to have the limited mass, the thin and light material should be selected and this necessity induces the decrease d natural frequency and structural stiffness. It reduces the ability of adapting to the disturbance and induces the structural unstability. Certainly, the disturbance does not only make the structural unstability, but also give the bad effect to the precise attitude control. So it is necessary to control the vibration in the space. In this paper, the flexible structure control modeling with piezo sensor and piezo actuator is developed. The model uncertainty of damping ratio is overcome by robust control. The system equation is induced by the finite element method.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제15권1호
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• pp.53-62
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• 2009

Healthcare facilities undergo substantial renovation and remodeling to accommodate changing technologies and regulatory requirements, thereby generating significant quantities of construction-related wastes, and subjecting building occupants to noise, dust, and other health impacting disruptions associated with construction. By designing flexible, adaptive, generic spaces, buildings can better respond to changes imposed by architectural composition of interpersonal and community space of hospital ward with minimum needs renovation and remodeling. This study focuses on the design principles of enhancing flexibility in architectural composition of interpersonal and community space of hospital ward. The purpose of this study is to provide fundamental data for designing interpersonal and community space of hospital ward through ecological flexible design principles with case on interpersonal and community space of hospital ward.

• 한국항공우주학회지
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• 제39권1호
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• pp.90-95
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• 2011

KSLV-I상단부 킥모터는 연소 중 피치 및 요 축 자세제어를 위해 플렉시블 씰이 적용된 구동 노즐을 사용하였다. 플렉시블 씰은 고무와 보강재를 번갈아 가며 적층하며, 고무의 변형을 통해 노즐이 회전할 수 있도록 한다. 따라서 플렉시블 씰 개발에서 노즐의 운용 조건에 맞는 고무를 개발하는 것은 매우 중요한다. 킥모터 플렉시블 씰 제작에 사용된 고무의 성능 평가를 위해 단축 인장시험, QLS 시험(전단 계수, 파단 전단응력), 노화 시험을 수행하였다. 시험 결과 고무의 전단 계수는 0.4310 ~ 0.4997MPa 범위를 가지며, 고무의 파단 전단응력은 2.5MPa 이상을 보이고 있다.

• 한국항공우주학회지
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• 제41권6호
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• pp.448-457
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• 2013

본 논문에서는 항공기 유연날개의 플러터 억제를 위한 능동 제어시스템을 슬라이딩 모드 제어기법을 이용해 설계하였다. 제어력으로는 유연날개 뒷전 조종면 움직임으로 발생하는 공기력을 이용하였으며, 이를 위해 공탄성 모델, 조종면 작동기 모델, 돌풍 모델로 구성되는 서보 공탄성 모델링을 수행하였다. 플러터 억제를 위한 조종면 제어시스템은 슬라이딩 모드 제어기와 측정값을 이용해 상태 변수를 추정하는 칼만 필터를 조합해 구성하였으며, 수치 시뮬레이션을 통해 유연날개 모델에 대한 플러터 억제 효과를 확인하였다.

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.70-81
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• 2017

Various components of an engine nozzle are modeled as flexible multi-body components that are operated under high temperature and pressure. In this paper, in order to predict complex behavior of an engine nozzle, thermo-fluid-flexible multi-body dynamics coupled analysis framework was developed. Temperature and pressure on the nozzle wall were obtained by the steady-state flow analysis for a two-dimensional nozzle. The pressure and temperature-dependent material properties were delivered to the flexible multi-body dynamics analysis. Then the deflection and strain distribution for a nozzle configuration was obtained. Heat conduction and thermal analyses were done using MSC.NASTRAN. The present framework was validated for a simple nozzle configuration by using a one-way coupled analysis. A two-way coupled analysis was also performed for the simple nozzle with an arbitrary joint clearance, and an asymmetric flow was observed. Finally, the total strain result for a realistic nozzle configuration was obtained using the one-way and two-way coupled analyses.