• 제목/요약/키워드: System dynamics modelling

검색결과 109건 처리시간 0.02초

구동력 계산법 및 H$\infty$제어를 병용한 직접구동방식 머니퓰레이터의 퀘적제어 (Robust Trajectory Control of Direct Drive Manipulator based on combining H$\infty$ Controller and Computed Torque Method)

  • Kim, C.K.;Kang, B.S.;Kwak, Y.K.
    • 한국정밀공학회지
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    • 제13권10호
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    • pp.123-129
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    • 1996
  • Computed torque method has been used for precise trajectory control of the robotic system that involves nonlinear dynamics. It is hard to know exact values of robot system parameters, and the robot arm receives umpredictable interference from the working environment. These disturbances, especially in a direct drive robot, are directly transmitted to actuating motor without reduction. Modelling error and distrubance can cause significant errors in a trajectory tracking problem. In this paper, we propose a new controller that $H_{\infty}$controller is conbined to robot system linearized by computed torque. Simula- tions are made for comparing the performance of the proposed controller with that of a nonlinear $H_{\infty}$ controller proposed by Chen and also computed torque method.hod.

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제지 공정의 효율적인 충전제 투입에 대한 동적 시뮬레이션 적용 (Application of Dynamic Simulation for Efficient Filler-Loading in Papermaking System)

  • 함충현;윤혜정
    • 펄프종이기술
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    • 제35권3호
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    • pp.1-12
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    • 2003
  • The complexity of the papermaking system accelerates interactions between a large number of variables involved. The process operation, therefore, is subject to frequent perturbations by disturbance. Dynamic modelling is a useful tool for characterizing the transient behavior and selecting the best control strategies to reject disturbances. In this study we developed a dynamic simulation model of a fine paper production process, which consists of stock preparation, wire sections, white water circulations, and broke system. It focused on dynamic simulation in its role for developing control strategies and studying control loop dynamics related to filler loading for ash control. The results emphasized the importance of filler-loading position and length of control loop for rapid ash control and process stabilization.

추사파중을 항행하는 선박의 자동조타 시스템 평가에 관한 연구 (A Study on the Evaluation of Automatic Steering System of Ships in Folowing Seas)

  • 이경우;손경호
    • 한국항해학회지
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    • 제25권4호
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    • pp.407-415
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    • 2001
  • In the present study, irregular disturbances to ship dynamics is proposed, where irregular disturbances implying irregular wave and the fluctuating component of wind for the evaluation of automatic steering system of ship in following seas. Prediction method based on the principle of linear superposition. Irregular wave disturbances in following seas is calculated by frequency variation method. The mathematical model of each element of an automatic steering system is derived, which takes account of a few non-linear mechanisms. PD(Proportional-Derivative) controller and low-pass filter with a weather adjustment are adopted to modelling the characteristics of an autopilot. Performance index is introduced from the viewpoint of energy saving, which derived from the concept of energy loss on ship propulsion. Finally, the present methods are applied to two typical types of ship ; an ore carrier and a fishing boat. The various effects of control constants of autopilot on propulsive energy loss are investigated

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고속 광 디스크 드라이브의 강인 서보제어 (Robust servo control of high speed optical disk drives)

  • 임승철;정태영
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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    • pp.438-444
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    • 1997
  • Recently, optical disk drives are increasingly demanded to have higher speed as well as high information density, especially for applications like CD-ROM drives. To this end, improvement of their optical pick-up structure and control is recognized the very challenging issue. In this paper, the 2-D motion of the pick-up is first analytically modelled to identify the cause and effect of the troublesome cross coupling between auto-focusing and tracking directions. Subsequently, the overall system equations are derived to include the dynamics of the related components in the auto-focusing servo system. While its unmeasurable parameters being estimated by the least square error method, a simple but decent linear model can be obtained within its operating frequency range. To design the high speed and robust positional servo controller, the design specifications are detailed and H$\sub$.inf./ control method is employed based on the simple model. Using the pickup in a commercial 8 fold speed CD-ROM drive as an example, performance of the designed controller is verified by realtime experiments.

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Comparative study of CFD and 3D thermal-hydraulic system codes in predicting natural convection and thermal stratification phenomena in an experimental facility

  • Audrius Grazevicius;Anis Bousbia-Salah
    • Nuclear Engineering and Technology
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    • 제55권4호
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    • pp.1555-1562
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    • 2023
  • Natural circulation phenomena have been nowadays largely revisited aiming to investigate the performances of passive safety systems in carrying-out heat removal under accidental conditions. For this purpose, assessment studies using CFD (Computational Fluid Dynamics) and also 3D thermal-hydraulic system codes are considered at different levels of the design and safety demonstration issues. However, these tools have not being extensively validated for specific natural circulation flow regimes involving flow mixing, temperature stratification, flow recirculation and instabilities. In the present study, an experimental test case based on a small-scale pool test rig experiment performed by Korea Atomic Energy Research Institute, is considered for code-to-code and code-to-experimental data comparison. The test simulation is carried out using the FLUENT and the 3D thermal-hydraulic system CATHARE-2 codes. The objective is to evaluate and compare their prediction capabilities with respect to the test conditions of the experiment. It was observed that, notwithstanding their numerical and modelling differences, similar agreement results are obtained. Nevertheless, additional investigations efforts are still needed for a better representation of the considered phenomena.

Consistent inflow boundary conditions for modelling the neutral equilibrium atmospheric boundary layer for the SST k-ω model

  • Yang, Yi;Xie, Zhuangning;Gu, Ming
    • Wind and Structures
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    • 제24권5호
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    • pp.465-480
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    • 2017
  • Modelling an equilibrium atmospheric boundary layer (ABL) in computational wind engineering (CWE) and relevant areas requires the boundary conditions, the turbulence model and associated constants to be consistent with each other. Among them, the inflow boundary conditions play an important role and determine whether the equations of the turbulence model are satisfied in the whole domain. In this paper, the idea of modeling an equilibrium ABL through specifying proper inflow boundary conditions is extended to the SST $k-{\omega}$ model, which is regarded as a better RANS model for simulating the blunt body flow than the standard $k-{\varepsilon}$ model. Two new sets of inflow boundary conditions corresponding to different descriptions of the inflow velocity profiles, the logarithmic law and the power law respectively, are then theoretically proposed and numerically verified. A method of determining the undetermined constants and a set of parameter system are then given, which are suitable for the standard wind terrains defined in the wind load code. Finally, the full inflow boundary condition equations considering the scale effect are presented for the purpose of general use.

유한 베어링 모델링을 이용한 왕복동형 압축기 크랭크축의 동적 거동 및 윤활특성 해석 (Dynamic Behavior and Lubrication Characteristics of a Reciprocating Compressor Crankshaft by n Finite Bearing Model)

  • 김태종
    • Tribology and Lubricants
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    • 제18권6호
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    • pp.402-410
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    • 2002
  • In this study, a hydrodynamic analysis of the reciprocating compressor crankshaft considering a finite bearing modelling of the journal bearings used in small refrigeration compressors is performed. In the problem formulation of the compression mechanism dynamics, all corresponding hydrodynamic forces and moments are considered using the finite bearing analysis in order to determine the crankshaft trajectory at each step. The solution of the Reynolds' equation is determined numerically using a finite difference method and a Newton-Raphson procedure was employed in solving the dynamic equations of the crankshaft. The crankshaft orbits fur the finite bearing model and short bearing theory were used to compare the effect of the hydrodynamic farces of the journal bearings on the dynamic and lubrication characteristics of the crankshaft-journal bearing system. Results show that the finite bearing model for the journal bearings must be considered in calculating for the accurate dynamic characteristics of the reciprocating compressor crankshaft.

Modelling the dynamic response of railway track to wheel/rail impact loading

  • Cai, Z.;Raymond, G.P.
    • Structural Engineering and Mechanics
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    • 제2권1호
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    • pp.95-112
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    • 1994
  • This paper describes the formulation and application of a dynamic model for a conventional rail track subjected to arbitary loading functions that simulate wheel/rail impact forces. The rail track is idealized as a periodic elastically coupled beam system resting on a Winkler foundation. Modal parameters of the track structure are first obtained from the natural vibration characteristics of the beam system, which is discretized into a periodic assembly of a specially-constructed track element and a single beam element characterized by their exact dynamic stiffness matrices. An equivalent frequency-dependent spring coefficient representing the resilient, flexural and inertial characteristics of the rail support components is introduced to reduce the degrees of freedom of the track element. The forced vibration equations of motion of the track subjected to a series of loading functions are then formulated by using beam bending theories and are reduced to second order ordinary differential equations through the use of mode summation with non-proportional modal damping. Numerical examples for the dynamic responses of a typical track are presented, and the solutions resulting from different rail/tie beam theories are compared.

헥사로터형 무인기의 모델링과 P-PD기반 비행성능평가 (Dynamic Model and P-PD Control based Flight Performance Evaluation for Hexa-Rotor Type UAV)

  • 진태석
    • 전기학회논문지
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    • 제64권7호
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    • pp.1074-1080
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    • 2015
  • In the last decades, the increasing interest in unmanned aerial vehicle(UAV) for military, surveillance, and rescue applications made necessary the development of flight control theory and body structure more and more efficient and fast. In this paper, we describe the design and performance of a prototype hexarotor UAV platform featuring an inertial measurement unit(IMU) based autonomous-flying for use in bluetooth communication environments. The proposed system comprises the construction of the test hexarotor platform, the implementation of an IMU, dynamic modeling and simulation in the hexarotor helicopter. Furthermore, the hexarotor helicopter with implemented IMU is connected with a micro controller unit(ARM-cortex) board. The P-PD control algorithm was used to control the hexarotor. We used the Matlab software to help us to tune the P-PD control parameters for quick response and minimizing the fluctuation. The control simulation and experiment on the real system are implemented in the test platform, evaluated and compared against each other.

흡입구 손실을 고려한 헬리콥터 추진시스템의 장착성능 해석 모델에 관한 연구 (A Study on Installed Performance Analysis Modelling for a Helicopter Propulsion System Considering Intake Loss)

  • 공창덕;구영주;고성희;기자영;차봉준;유혁
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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    • pp.263-267
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    • 2008
  • 본 연구에서는 헬리콥터 추진시스템의 장착 성능해석 모델링 시 고려하여야 할 흡입구 모델, 블리드 공기 손실, 보기류 시스템 구동에 사용되는 출력 추출 등을 포함한 장착 성능해석을 수행하였다. 흡입구의 압력 손실은 비행마하수와 유량에 따른 압력손실 값으로 나타낸 흡입구 성능 맵을 이용하였다. 추진시스템 장착 성능해석 모델링의 검증을 위해서는 실제 시험데이터와 비교해야 하지만 데이터 확보가 어려워 상용성능해석 프로그램인 GASTURB 해석결과와 비교 하였다. 해석결과 평균오차 0.5% 이내로 본 연구에서 수행한 추진시스템의 장착 성능해석 모델링의 타당성을 검증하였다.

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